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Optimized Design and Implementation of a SiC MOSFET Gate-Isolated Drive Circuit Based on Planar Coreless Transformer

Hua Xing Yu, Zhang Yi, Lu Yu Fang, Huang Zhi Ai, Jiang Zhi Jun, Deng Ming

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This paper proposes an optimized design method for a gate-isolated drive circuit of SiC MOSFETs based on planar coreless transformer technology. The circuit topology was first determined according to the requirements of high-voltage solid-state power controllers (SSPCs). Following this, key parameters such as trace width and coil diameter were defined under PCB fabrication constraints, and a near-field coupling model was established for co-simulation with peripheral circuits. Subsequently, circuit parameters were optimized through theoretical and simulation analysis, culminating in the fabrication and experimental evaluation of prototype samples. Experimental results demonstrated that the optimized design achieves a planar coreless transformer diameter reduction to 8 mm, transmission efficiency exceeding 83%, and SiC MOSFET switching times of ≤56 μs (turn-on) and ≤100 μs (turn-off). Additionally, the proposed circuit enables real-time switching state detection while exhibiting significantly enhanced noise immunity compared to conventional solutions, addressing critical challenges in miniaturization and high-performance power device control.
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A multi-parameter water quality prediction algorithm based on spatial-temporal graphical convolutional networks

ye bin qiang, cao xue jie, li dong, chen chang hong, liu hong, tang bin, feng peng

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Water quality prediction is essential for ecological water management. Water quality exhibits complex non-stationary dynamics and multi-dimensional nonlinear relationships due to temporal evolution and environmental changes. In multi-parameter prediction of river water quality, the spatial-temporal dependence is complex, and traditional models struggle to integrate dynamic topology with? long-period features effectively. Therefore, we propose a spatial-temporal graph convolutional network model. In the temporal dimension, a masked sub-series transformer module extracts long-term trends through self-supervised pre-training. Combined with dilated causal convolution, it captures cumulative water quality effects. It solves the lag problem of traditional models in responding to sudden changes. In the spatial dimension, a dynamic graph learning module fuses a predefined station-distance adjacency matrix with a dynamic residual map to generate adaptive graph structures. Experimental results demonstrate that our model outperforms existing methods for predicting water quality. The prediction R2 for all water quality indicators exceeds 93%.
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Energy-saving control method for excavator arm retraction with intelligent load direction recognition

Liu Yuchao, Gao Guoqiang, Sun Yifan, Ling Huzhao, Yang Shuyi, Liu Chaofu, Xi Yi

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To address the high energy consumption issue caused by throttling losses during hydraulic excavator arm retraction, this paper proposes an energy-saving control method for arm retraction based on intelligent load direction recognition. First, by utilizing displacement sensor data from the boom, arm, and bucket cylinders, a kinematic model of the arm and bucket system is established to calculate the composite center of gravity in real time and predict the theoretical transition interval where the load force on the arm cylinder shifts from pulling to pushing. Then, the actual load force is dynamically calculated based on pressure data from both chambers of the cylinder, enabling accurate identification of the transition point from pulling to pushing within the theoretical interval. Finally, the return hydraulic circuit of the arm is redesigned along with a corresponding energy-saving control strategy to reduce energy loss during the return process. Experimental results demonstrate that, while ensuring smooth operation during arm retraction, the energy consumption during the pushing phase is reduced by 40.8%, and the total energy consumption of the complete retraction cycle is decreased by 17%. This study provides an engineering-feasible technical approach for energy-saving optimization in hydraulic excavator arm retraction operations.
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Lidar-Monocular Camera Mutually Fused Odometry Guided by Visual Feature

Zhang Wenlong, Chen Du, Ning Shangzhi, FU Chunyun

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The effective fusion of monocular camera can enhance the robustness and accuracy of Simultaneous Localization and Mapping (SLAM) tasks.. However, most existing camera-LiDAR fusion SLAM methods are unidirectional and do not fully utilize the rich textural information from camera images to guide the registration process of point clouds. To address this issue, this paper proposes a bidirectional fusion odometry of monocular camera and LiDAR guided by visual feature points. This odometry enhances the robustness of visual feature point depth estimation using a dual-plane method. It also predicts the projection positions of current-frame LiDAR points in adjacent frames based on the matching relationships of visual feature points. Furthermore, it constructs a potential LiDAR point cloud matching set for the current frame by leveraging the characteristics of co-visible keyframes, thereby accelerating the speed and accuracy of point cloud registration. Extensive experiments were conducted on the KITTI dataset and our self-collected dataset. The results show that the proposed bidirectional fusion odometry not only achieves better accuracy and robustness in pose estimation compared to existing methods but also produces more realistic 3D reconstruction results.
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Multi-objective Optimization of T-beam Formwork for Lightweight Structural Design

Cao Xuepeng, Lu Jiangfeng, Liu Xiaohui, Cao Leilei, Wang Binhua, Duan Baohong

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To resolve the conflict among strength, stiffness, and lightweight requirements in T-beam formwork design with multiple parameters, this study proposes a multi-objective optimization framework. A representative sub-section template was analyzed using finite element analysis (FEA) to evaluate stress and deformation. Design variables included channel steel spacing, stiffener spacing, and panel thickness. The NSGA-III algorithm was employed to minimize maximum stress, deformation, and mass while satisfying mechanical constraints. Optimization results show that the sub-section template achieved a 38.66% mass reduction: panel thickness decreased from 6 mm to 3.6 mm, with unevenly spaced channel steels and stiffeners. Validation on the full-scale T-beam formwork demonstrated a 19.44% lightweight improvement while meeting stiffness and strength standards. This method effectively balances performance and lightweight goals, offering practical value for large-scale structural optimization.
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Lightweight Medical Image Segmentation using Randomized Diverse Scribble Prompting

JIA Xuxiang, LI Zhenghao, ZHANG Zhiwei, SUN Dong, CHENG Peng, XU Qiang, ZHANG Lijun, SHI Yu

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Medical image segmentation, as a crucial component of computer-aided diagnosis, has witnessed remarkable progress in recent years under the "prompt-segmentation" paradigm based on large models. MedSAM has demonstrated excellent performance in medical scenarios but requires substantial computational resources. LiteMedSAM, a lightweight version, is suitable for resource-constrained environments, yet it does not fully utilize diverse mask information during the prompt encoding stage, making it difficult to achieve ideal segmentation results under conditions of sparse annotations. To address this issue, a lightweight medical image segmentation algorithm based on random diverse scribble prompts is proposed. This algorithm maintains the lightweight nature of LiteMedSAM while incorporating three modules: random diverse scribble generation, adaptive prompt weight based on Gumbel-Softmax, and multi-level gate fusion, which are well-suited to the prompt encoder structure. Specifically, it first uses the global representation of sparse prompts to pre-select the most discriminative scribble patterns at the logical level, then randomly generates multiple binary masks with diverse geometric shapes based on adaptive weights, and finally fuses the mask prompts with maskless prior information through a spatial-channel-level gating mechanism with dynamic weighting. Experimental results show that, without significantly increasing computational costs, the proposed method achieves higher Dice similarity coefficients (DSC) and normalized surface distances (NSD) on multiple medical image segmentation datasets compared to LiteMedSAM. Currently, this method has been successfully applied in the scenario of medical image radiation dose assessment, confirming its clinical application value.
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Analysis of traveling wave resonance characteristics in aviation thin-webbed spur gears

LIU Hang, SONG Chaosheng, YANG Qiyong, XU Xiangyang, LI Lang

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To address the severe traveling wave resonance caused by axial excitation resulting from system deformation in a lightweight thin-webbed gear under asymmetric support conditions, a finite element model was established that comprehensively considers casing stiffness and gear tooth meshing conditions. Through pre-stressed modal and harmonic response analyses, the traveling wave resonance characteristics within the operational speed range were investigated, and the influence of the gear’s structural parameters on this resonance was studied. Although spur gears generate no axial force under ideal conditions due to their tooth geometry, asymmetric arrangements can lead to misalignment caused by shaft deflection or bearing deformation. This misalignment decomposes the radial force into an axial component, exciting traveling wave resonance, with the axial vibration behavior primarily governed by the gear’s structural characteristics. The study reveals that thin-webbed spur gears are prone to structural vibration within the operational speed range, exhibiting high energy in low-order modes and lower energy in higher-order modes, making them susceptible to low-frequency traveling wave resonance. Furthermore, under lightweight constraints, increasing the thickness of the web and rim effectively raises the natural frequency and significantly reduces vibrational stress, albeit at the cost of added weight. In contrast, increasing the web offset distance reduces the support stiffness, aggravating vibrational stress.
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Research on helicopter magnetorheological seat suspension for cushioning and vibration isolation

DONG Xiaomin, RAO Zhicheng, XU Di, Chen Yanhe, CHEN Taofu, LI Yong, LONG Lingtao

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Long-term vibration will affect the efficiency of pilots to perform tasks and endanger their health. Aiming at the problem that it is difficult to effectively balance the cushioning and vibration isolation performance of helicopter seats, a helicopter seat system scheme based on the integrated cushioning and vibration isolation function of a new type of double-disc rotary magnetorheological damper was proposed. Through the mechanical modeling of the designed damper, the multi-degree-of-freedom nonlinear dynamic model of the seat system was established, and based on this, the simulation analysis of the dual-condition control strategy of the seat system was carried out. Finally, the experimental prototype of the damper was processed, and the performance of the seat system was verified by experiments. The simulation and experimental results show that the new damper has the advantages of large adjustable range and high output torque density. The proposed seat system can meet the buffering requirements of the crash condition, and can effectively suppress the vibration transmission under the vibration isolation condition, which verifies the effectiveness of the seat system.
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Anti-windup H∞ control for flexible satellites attitude based on full-order dynamic observer

huangdeqin, Hei Luhao, Zhou Yanru, Tang Weiqiang

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To meet the high-precision attitude control requirements of flexible satellites, this paper proposes an anti-windup H∞ control method based on a full-order dynamic observer to address the issues of composite disturbances and actuator saturation constraints during maneuvers. By leveraging the structural characteristics of the flexible satellite attitude system, an H∞ controller integrated with a full-order dynamic observer is designed through the application of Lyapunov stability theory and linear matrix inequality (LMI) techniques. Furthermore, an anti-windup compensator is developed based on the input-output characteristics of the actuator to mitigate input saturation effects without increasing the dimensionality of the control system. Finally, the validity of the method, along with its practical feasibility, is confirmed through numerical simulations.
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Analysis of Bridge Buffeting Response Considering the Effects of Offshore Water Surface Sublayers

lubin, yanfulai, caisong, xiezeen, lijiawu

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To investigate the influence of the underlying sea surface layer on the buffeting response of long-span bridges, an offshore suspension bridge was selected as the subject. A numerical wave flume was constructed using the SST k-ω turbulence model and the Volume of Fluid (VOF) method. The evolution of wind profiles with the fetch distance over the water surface was analyzed. Addressing the issue of significant variations in aerodynamic forces on the girder with navigation clearance height due to the underlying surface layer, the “Effective Three-Component Force Coefficient Correction Method” was proposed. This method corrects the three-component force coefficients of the girder based on a gas-liquid two-phase flow model over a static water surface. Combining the harmonic synthesis method and time-domain buffeting analysis, the wind profile evolution, coefficient correction, and their coupled effects were quantitatively evaluated. Results indicate that: The wind profile evolution rate exhibits a trend of being “initially rapid followed by gradual”, stabilizing at a fetch distance of 1000 m. At this point, the buffeting response shows an average attenuation of 10% compared to the conventional uniform wind profile assumption. After correction, the deviation of the three-component force coefficients increases with decreasing height, leading to significant enhancement in lateral and torsional buffeting responses, with a maximum increase of 30%. Findings reveal that: Buffeting analysis for offshore bridges must fully account for the influence of the underlying surface layer, and the correction of the three-component force coefficients plays a particularly crucial role.
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Optimization Techniques for Secrecy Capacity in UAV Relay Systems Assisted by Artificial Noise

Hao Yunqi, XIANG Youyang, LI Xianglu, DING Chen, Du Qilong, HOU Dong, TIAN Jie

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The broadcast nature of wireless channels exposes them to severe eavesdropping risks, particularly when the eavesdropper is geographically close to the legitimate receiver. In such scenarios, the Channel State Information (CSI) of both parties exhibits high correlation or even superior quality for the eavesdropper, rendering traditional power optimization methods ineffective in reducing the eavesdropping rate. To address this issue, a secure transmission strategy for unmanned aerial vehicle relays is proposed, based on power allocation factor optimization. By dynamically adjusting the power allocation factor to control the power ratio of Artificial Noise (AN), adaptive interference control over the eavesdropping channel is achieved. A four-node communication system is constructed, comprising a source node, a UAV relay, a legitimate receiver, and an eavesdropper. A non-convex optimization problem is formulated with the objective of maximizing secrecy capacity. Through the introduction of slack variables and the Successive Convex Approximation (SCA) method, the original problem is transformed into a convex optimization problem. Combined with the Staircase Water Filling (SWF) method, a closed-form analytical solution for the power allocation factor is derived, and an alternating iterative optimization algorithm is proposed to achieve global parameter optimization. Simulation results demonstrate that the proposed algorithm reduces eavesdropping capacity by 76% compared to traditional power optimization algorithms, significantly enhancing the system's security performance.
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The Impact of Coal Rock Mass on the Geochemical Evolution of Major Cations in Mine Water

lukaixuan, lukaixuan, luoqing, luojie, xulianman

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Discharge of mine water has drawn increasing concern due to its contribution to elevated river salinity and soil salinization. Understanding the evolution of cations in mine water is crucial for developing efficient treatment technologies. This study investigated the release patterns of major cations from coal and gangue collected from the Pingdingshan mining area under various conditions, including particle size and solution chemistry. The underlying mechanisms controlling the mineralization characteristics of mine water were elucidated. The results showed that the particle size of coal and gangue significantly influenced ion release and solution pH. A smaller particle size enhanced the dissolution of aluminosilicates and carbonates in the coal-bearing strata, leading to increased release of primary ions such as Si and Al. Gangue was the primary source of Si and Al ions, while coal predominantly contributed Ca ions; furthermore, the presence of gangue suppressed the release of Ca ions. The ion release patterns in actual mine water differed from those in deionized water, with Ca and Mg concentrations in mine water being mainly governed by coal. The study demonstrates that the synergistic interaction between coal and gangue significantly impacts the chemical properties of mine water, while the initial solution environment primarily regulates the dynamic processes of ion release and pH changes. By systematically revealing the evolution of major cations under different particle sizes, this research clarifies the chemical behavior of coal and gangue within the mine water system and its influence on water quality, providing valuable insights for reducing treatment costs and developing innovative technologies for managing highly mineralized mine water.
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Design of current band gap start circuit with dynamic threshold control

Xin Cong, Zhou Xingmin

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A novel startup circuit for current-mode bandgap reference (CMBGR) is proposed to resolve startup issues in low-voltage CMOS processes while simultaneously addressing design cost, PVT (Process, Voltage, Temperature) robustness, CMBGR performance, and curvature compensation compatibility constraints. The circuit employs a dynamic threshold voltage mechanism implemented in 0.11 μm CMOS technology, utilizing a simple design that dynamically adjusts the startup threshold to ensure reliable operation across varying PVT conditions. Validation was conducted through 20,400 Monte Carlo simulations under diverse PVT settings, all confirming successful CMBGR startup without failure. The CMBGR operates across a supply voltage range of 2.3–4.3 V, delivering a configurable reference voltage output from 0.1 to 2.0 V. A temperature coefficient of 8.7 ppm/°C was achieved, maintaining the inherent low-temperature-coefficient characteristic of CMBGR. The design preserves CMBGR's configurability and compatibility with existing curvature compensation strategies, eliminating the need for additional circuitry or performance trade-offs. This approach provides a comprehensive solution for stable startup in configurable CMBGR applications
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Research on ion-doped PZT films

Li Jizhen, Song Yihui, Yang Danni, Mu Xiaojing, Wu Liangke

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To address the bottleneck issues of low energy conversion efficiency and single performance regulation method in existing PZT thin films, this paper focuses on the problem of insufficient piezoelectric performance of PZT thin films and investigates the effects of A-site doping with La3+ and Ba2+ on the electrical properties of PZT thin films, as well as analyzes the doping modification mechanism. Lead lanthanum zirconate titanate (PLZT) thin films and lead barium zirconate titanate (PBZT) thin films were prepared by the sol-gel spin-coating method. Furthermore, the effects of A-site co-doping of La3+ and Ba2+ on the performance regulation of PZT thin films were studied. The crystal structures and electrical properties of PLBZT thin films with different doping ratios were compared. The results show that the co-doping of La3+ and Ba2+ can synergistically improve the electrical properties of the thin films. The optimal performance is achieved with the co-doping of 2% La3+ and 2% Ba2+ (P1.06L0.02B0.02ZT). Compared with the PZT thin film, the dielectric constant ε? of the P1.06L0.02B0.02ZT thin film is 1718.3 (an increase of 75.23%), and the piezoelectric constant d?? is 244.1 pC/N (an increase of 39.65%)..
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Solution Method for Open-Pit Coal Mine Truck Scheduling Model Based on Improved Grey Wolf Optimisation Algorithm

guowei, bairuncai, renshihao, Li Hong, gaolei, wangzihao

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This paper proposes an adaptive grey wolf optimizer based on mutation strategies and generalized opposition-based learning (GOBL-IGWO) for optimizing truck dispatch in open-pit mines. To address the slow convergence in later stages and imbalance between global exploration and local exploitation capabilities inherent in the traditional grey wolf optimizer (GWO), an adaptive parameter adjustment mechanism, a generalized opposition-based learning strategy, and wolf pack mutation strategies were introduced. These modifications effectively enhanced the algorithm"s convergence and stability.2Comparative experiments evaluated the GOBL-IGWO algorithm against particle swarm optimization (PSO), differential evolution (DE), the traditional GWO, and an improved PSO (IPSO) using the CEC2005 benchmark functions (F1-F25). Results demonstrated that GOBL-IGWO exhibits superior optimization performance across unimodal, multimodal, hybrid, and composition functions. The algorithm showed particularly strong global search and local development capabilities on complex multimodal functions, effectively avoiding local optima. Furthermore, GOBL-IGWO significantly outperformed the compared algorithms in both convergence speed and solution accuracy, demonstrating higher optimization performance and robustness.These findings indicate that the GOBL-IGWO algorithm better adapts to the complexity and real-time requirements of open-pit mine truck scheduling problems. It provides a more reliable solution for practical applications, holding significant practical significance for improving mine transport efficiency and reducing production costs.
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Improved Spacer Target Detection Based on YOLOv12

huangxuefei, dingzushan, lumenglong, wangyiding

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Spacers in power transmission lines are primarily employed to maintain an appropriate distance between conductors, preventing collisions or contact between them. As the scale of power transmission networks continues to expand, the detection of spacer bars on transmission lines becomes critical for ensuring the safety of the conductors. To address these issues, this paper proposes an improved spacer detection algorithm based on YOLOv12. First, to mitigate the impact of various natural environmental factors that often degrade image quality, an image preprocessing strategy is introduced to enhance the clarity of training samples. Second, to address the small proportion of spacers in the image and the risk of losing crucial information during convolutional down-sampling, the Space-to-Depth Convolution (SPDConv) block is incorporated to preserve informative features and improve detection accuracy. Additionally, due to the lack of publicly available datasets tailored to this task, a new spacer image dataset covering a range of complex real-world scenarios was constructed. Experimental results on this dataset demonstrate that the proposed model outperforms the baseline YOLOv12 model, achieving an 8.2% improvement in precision and a 10.8% increase in recall. These results confirm the effectiveness and feasibility of the proposed approach for accurate spacer detection under complex real-world conditions.
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Optimization and Comparative Analysis of Stope Structural Parameters in Laoheba Phosphate Mine

Yuan Haoyang, Hu Junwei, Huang Gun, Xiong Yangtao

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The optimization of stope structural parameters and stability analysis in phosphate mines are of great significance for ensuring safe and efficient mining production. This study, based on the Laoheba Phosphate Mine as the engineering background, conducts research on the optimization of stope structural parameters and compares the stability before and after optimization. First, an orthogonal experimental design was used to develop a multi-factor, multi-level combination scheme for stope length, stope width, and pillar width. Then, through numerical simulation, key indicators such as roof displacement, stress distribution, pillar stress state, and the proportion of the plastic zone were systematically analyzed. After comprehensive weighted evaluation, the optimal stope parameters were determined as follows: stope length of 25 m, stope width of 10 m, and pillar width of 8 m. Further numerical simulation compared the ultimate bearing capacity of pillars before and after optimization. The results show that the optimized parameters significantly reduced the proportion of the plastic zone in the pillars, enhanced their load-bearing capacity, and, due to the increased stope area, improved mining efficiency. This study can provide a theoretical basis and technical reference for stope structural design and stability control in similar mines.
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Strength prediction of planar woven composites based on thecohesive interface model

SUN Jiawen, YAO Jianyaoa, YE Wei

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Planar woven composites, renowned for their superior mechanical properties and design flexibility, are extensively used in aerospace and automotive industries. However, their anisotropic nature and multi-scale damage mechanisms pose challenges in predicting their mechanical behavior. This paper addresses the progressive damage behavior of planar woven composites by developing a multi-scale damage analysis model. The study systematically investigates the material"s damage failure process and ultimate strength. Initially, a finite element model incorporating fibers, matrix, and interface is established based on a representative volume element at the microscale fiber bundle level. Cohesive elements are employed to simulate interface failure between the matrix and fibers, while Tsai-Wu failure criteria and stiffness recursive reduction schemes are utilized to model the initiation and accumulation of fiber bundle damage. Subsequently, a scale-bridging approach is applied to simulate the damage failure process and ultimate strength of planar woven composites, which is validated through comparisons with existing experimental results.
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Effect of binder contents on microstructure and mechanical properties of TiC-based cermets

Xuyang Liu, Botao Wu, Zhu Jun, Qingzhu Sun, Li Jia, Junjie Wang, Lei Xie, Chen Min

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Abstract: TiC-based cermets have been widely used in wear parts and cutting tools due to their excellent properties such as low density, high hardness, good high-temperature oxidation resistance and so on. Effect of binder content on the microstructure and mechanical properties of TiC-based cermets was investigated using X-ray diffraction, scanning electron microscopy observation, microhardness tests and transverse rupture strength tests. Results showed that when the binder content was 15wt%, the TiC-based cermet has best mechanical properties. The hardness, flexural strength and fracture toughness are 1668 HV, 1377MPa, 7.76MPa/mm1/2, respectively. Increasing binder content is beneficial to promote liquid sintering. However, when the binder content increased to 21wt%, the content of dissolved carbides in liquid increased, the mechanical properties decreased due to coarsened surrounding rims.
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Multi-scale Reliability Optimization of Honeycomb Sandwich Composites Based on Interval Uncertainties

PENG Shang, NING Huiming, SUN Dongyang

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A multi-scale reliability optimization method for honeycomb sandwich composites is proposed based on interval theory. We first develop parameterized finite element models at the microscale for both the face sheets and the core, using a generalized representative volume cell approach to capture the multi-scale characteristics of the material. These models yield the effective mechanical properties of the constituents. We then integrate these homogenized properties into a macroscopic parameterized finite element model of the sandwich structure under three-point bending to evaluate its global mechanical response. Next, we construct a multi-scale reliability optimization model that incorporates interval uncertainties and uses the possibility level of the bending performance as a constraint. To improve computational efficiency, we perform global sensitivity analysis based on interval theory to identify key design and uncertainty parameters. This enables us to reduce the problem"s dimensionality and formulate a more efficient reliability optimization model. Finally, we verify the proposed method through numerical simulations. The results show that, under a 60% possibility level, the optimized design reduces structural weight by approximately 16% and lowers cost by about 22%, while maintaining comparable bending and shear stiffness.
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Analysis of cumulative plastic deformation under three-phase short-circuit impact in large-capacity power transformers

HAO Yuefeng, LIU Jun, SHI Lintao, XU Shurong

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The cumulative plastic deformation of the windings in transformers during short-circuit impacts is the primary cause of transformer accidents. Among these, large-capacity power transformers are more prone to significant plastic deformation during short-circuit impacts due to higher short-circuit currents. Currently, both domestically and internationally, research on cumulative plastic deformation in large-capacity transformers during reclosing operations has primarily focused on the ageing of spacers and qualitative measurements of deformation quantities, while analyses of the mechanisms underlying cumulative plastic deformation in windings and the influencing factors on structural components remain insufficient. To investigate the mechanism of cumulative plastic deformation, a computational model based on electromagnetic-structural coupling was established to simulate the cumulative plastic deformation of transformer windings under three-phase short-circuit conditions. This model was used to study the cumulative plastic deformation of large-capacity power transformers under six three-phase short-circuit impacts. The computational results show that the cumulative plastic deformation of the windings increases with the number of short-circuit impacts, while the cumulative rate gradually decreases, and the total cumulative deformation tends to saturate. Additionally, a comparison was made between the transformer under fully constrained conditions of the upper pressure plate structural components and the transformer under unconstrained conditions following the failure of the upper pressure plate. The computational results indicate that after the upper pressure plate fails, the impact of vibrations increases, enhancing the transformer"s resistance to short-circuit impacts, while the rate of cumulative plastic deformation slows down.
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Study on the Water Environment and “Nature-Society” Evolution Process in the Source Region of the Yangtze River

WEN Chuan, SHAO Ying, ZHANG Zhi, CHEN Zhong-li, YANGYang

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The source region of the Yangtze River, as a crucial freshwater resource supply area in China and an essential component of the ecological security barrier on the Qinghai-Tibet Plateau, exerts significant influence on the ecological security and sustainable development of the Yangtze River Basin and even the entire nation through its water environment quality and the evolution process of the “nature-society” system within the watershed. This study examines the hydrological and environmental dynamics of the Yangtze River source region through a dual analysis of water flow evolution and water quality changes. First, based on hydrological and climatic data from 1956 to 2022 (67 years), we project future runoff trends at the basin outlet, revealing fluctuations of approximately ±15% driven by precipitation variability and rising temperatures. Second, by integrating water quality monitoring data (2012–2022), land use changes, and the "Production-Living-Ecology" (PLE) model, we assess long-term water environment quality and its interplay with human activities. Our findings indicate that the water quality in the region has consistently met Class II standards, affirming its suitability as a drinking water source and a conservation zone for rare aquatic species. Furthermore, comparative analysis of Golmud City and Yushu City demonstrates divergent PLE functional evolution, with Yushu exhibiting stronger synergy among the "triple functions" and greater potential for harmonizing ecological preservation with socioeconomic development. This research provides a scientific foundation for sustainable management strategies in the Yangtze River source region.
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Compressive Characteristics and Hyperbolic Model of Gap-graded Coral Sand

ZHANG Xiaoyan, WANG Yaling, LI Qiang, Wang DongYu, WU Yang

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The coral sand with coarse and fine sized particles forms a discontinuous graded coral sand strata under hydraulic sorting. Under complex ocean dynamic conditions, fine particles are prone to loss leading to internal erosion, posing significant challenges to the stability of island and reef foundations. To further investigate the internal erosion mechanism of gap graded coral sand, high-pressure oedometer tests were conducted on three types of gap-graded coral sand samples. The compression coefficient of gap-graded coral sand shows a trend of first increasing and then decreasing with the increase of fine particle content. The relative breakage of gap-graded coral sand decreases linearly with the increase of fine particles. In the mixed sample, when the content of fine particles is low, fine particles mainly fill the voids between coarse particles, and the particle crushing is mainly dominated by coarse particles. The compression coefficient is affected by the ratio of coarse and fine particle. When the fine particle content exceeds the transition fine particle content of 50 %, the coarse particles are surrounded by fine particles, and the coarse particles are almost not broken, and the compression coefficient is almost not affected by the ratio of coarse and fine particle. The curves of coral sand with different fine particle contents can be represented by a hyperbolic model, and the model parameter b is the reciprocal of the initial porosity ratio, and the model parameter a is related to particle breakage. The compression characteristics of gap-graded coral sand under extremely high stress were reasonably predicted by this model. Under extremely high stress, the smaller the ratio of coarse to fine particles, the better the convergence of the compression curve. This study can provide theoretical guidance for the construction of island and reef infrastructure, and has certain academic value and broad engineering application prospects.
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Multi-scale Interpretable Temporal Prediction Network for Building Energy Consumption Forecasting

YANG Liejuan, TAN Guopeng, CAO Qi, YANG Huiyue

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Building energy consumption forecasting is crucial for optimizing energy management, reducing operational costs, and achieving carbon neutrality goals. To improve prediction accuracy and result reliability, this study proposes a Multi-Scale Interpretable Temporal Prediction Network Model(ITSFN) through the collaborative optimization of Long Short-Term Temporal Networks (LSTM) and Kolmogorov-Arnold Networks (KAN). The model integrates temporal-environmental feature decoupling and a dynamic attention mechanism, explicitly decomposing time-series data into seasonal, trend, and residual components to construct a structured feature space. It employs a parallel architecture of Gated Recurrent Units (GRU) and multi-head attention for multi-scale feature modeling. Tested on an energy consumption dataset from a university teaching building in a hot-summer/cold-winter region, the results show that ITSFN reduces the RMSE of total energy consumption prediction by 13.9% compared to LSTM and decreases the RMSE of sub-item energy consumption prediction by 31.1% compared to Transformer. Additionally, ITSFN enhances the noise suppression coefficient to 0.89 through feature decoupling, achieves a local attention angle of 0.92 in mutation regions, and reduces over-smoothing by 29.6% compared to traditional methods. By quantifying feature contributions, it reveals the evolutionary patterns of component weights, validating the model"s effectiveness and practicality.
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Mechanical-hydraulic co-simulation of new double-cylinder anchor sealing mechanism of pipeline intelligent plugging robots

tangyang, yanwenbo, xujiaqing, zhouminghai, wangguorong, wangmingbo, pangrenshan

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The anchor sealing mechanism directly affects the safety and reliability of the high-pressure plugging operation of the intelligent plugging robot in the maintenance and repair of long-distance oil and gas pipelines. In order to evaluate the dynamic performance of the new anchor sealing mechanism and its hydraulic control system, shorten the development cycle and improve the design reliability, this paper uses the joint simulation method of virtual prototype and hydraulic control system to analyze the working process of the pipeline intelligent plugging robot in the anchoring and plugging stage, and carries out the functional test. The results show that the thrust of the anchored hydraulic cylinder is 252.5kN under the condition of 10MPa oil and gas pressure, and the relative error with the joint simulation result of 234kN is 7.3%. The thrust of the sealing hydraulic cylinder is 718.76kN, and the relative error with the joint simulation result of 658kN is 8.45%, and the maximum error does not exceed 8.45%, which meets the requirements of engineering application. The inlet flow rate of the anchoring hydraulic cylinder is 9.2L/min and the pressure is 29.8MPa. The inlet flow rate of the plugging hydraulic cylinder is 8.05L/min and the pressure is 25.9MPa, which are in line with the design range. The test results are basically consistent with the simulation data, and the system runs smoothly and reliably. The research verifies the feasibility of the new double-cylinder anchor sealing mechanism, which is of great significance to improve the reliability of the design of the pipeline intelligent plugging robot and the value of engineering application.
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Research on Contact Pressure Measurement Method for PP-IGBT Based on Ultrasonic Technology

LI Ying, MA Kai, DUAN Zeyu, LI Hui, LAI Wei, TAN Lingqi, JIANG Liantao, LIU Renkuan, YAN Xiaoxue, LIAO Yu

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The contact pressure within PP-IGBT devices is unevenly distributed due to the height tolerance dispersion of the packaging materials during the production process, but the existing contact pressure measurement method is intrusive and difficult to be applied in online state monitoring, a modeling method for contact pressure measurement of PP-IGBT devices based on ultrasonic non-invasive technology is proposed. Firstly, the two-dimensional ultrasonic simulation model of PP-IGBT device is established based on the package material size. Secondly, the ultrasonic response of contact interface under different pressure is studied by using equivalent displacement of contact surface. Finally, the simulation results are verified by a single chip device pressure test. The results show that the maximum error between simulation and experimental results is about 4.35%, and ultrasonic reflection amplitude decreasing with the increase of contact pressure is verified. The research results provide a theory for the application of ultrasonic technology to the accurate measurement of contact pressure distribution within PP-IGBT devices, which is of great significance to the safety of system operation.
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Research Status of MIG Welding of Magnesium Alloy

pengjian

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Metal inert gas (MIG) welding provides the advantages of a high deposition rate, high thermal efficiency, and facilitates readily automated, efficient production. Magnesium alloys have broad application prospects in transportation, aerospace and other industries due to their high specific strength and good damping performance. MIG welding is a suitable welding method for magnesium alloys, and there have been a large number of researches and technological developments. This paper introduces the research status of MIG welding of magnesium alloys, reviews the related research on droplet transition mode, microstructure, and MIG hybrid welding, and looks forward to the future research directions of MIG welding of magnesium alloys.
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Effect of heat treatment on microstructure and mechanical properties of Ti86Al9Fe2Mo3 alloy

Jiawei Chen, Xuyang Liu, Min Chen, Zhongxue Feng, Chenlu Liu

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A novel low-cost titanium alloy Ti₈₆Al₉Fe₂Mo₃ was designed based on the d-electron theory. The evolutionary relationships between microstructure and mechanical properties of the alloy under different aging temperatures (700 °C, 740 °C, and 820 °C) were investigated. The results show that with the increase of aging temperature, the content of β phase gradually increases while that of α phase decreases, and the size of β phase tends to decrease with a more uniform distribution. Temperature, the content of β phase gradually increases while that of α phase decreases, and the size of β phase tends to decrease with a more uniform distribution. Among the tested conditions, the alloy aged at 700 °C exhibits the optimal comprehensive mechanical properties, with a tensile strength of 2160 MPa and an elongation of 42%, which are 42.01% and 61.5% higher than those of the as-cast alloy, respectively. Additionally, as the heat treatment temperature increases, the fracture mode of the alloy transforms from brittle fracture to ductile fracture.
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Temperature corrected load forecasting for reliability assessment

ZHU Zihan, XIE Kaigui

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Aiming at the problems that the existing research methods do not adequately describe the quantitative relationship between time series accumulated temperature effect and power load change, and it is difficult to adapt to the rapidly changing climate environment, this paper proposes a long-term load time series forecasting method based on deep reinforcement learning for reliability assessment and considering the accumulated temperature effect. Firstly, the temperature correction model is learned through the depth deterministic strategy gradient method to quantify the nonlinear relationship between high temperature and load, reflect the impact of high temperature weather on the cumulative rise of load, and modify the climate temperature. Secondly, the other important influencing factors of power load except temperature are screened out, and the influencing factor data are preprocessed. Finally, based on the historical load, the corrected temperature data and the data of other influencing factors, the STL-LSTM-FED model is used to predict the long-term load time series data. The actual data of a province from 2012 to 2014 are selected for example analysis. Experiments show that, compared with the traditional method, the prediction accuracy of the model in extreme high temperature scenarios has been significantly improved, which verifies its adaptability to complex climate conditions. The research results not only improve the climate adaptability of load forecasting, but also provide data support for evaluating the security and stability margin of power grid equipment and reserve capacity configuration under extreme disaster scenarios by accurately capturing the load growth mode caused by temperature accumulation effect, and effectively enhance the prediction ability of power grid reliability.
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Monitoring technology of wind deviation of transmission line based on Power line intelligent spacing bar

WU Haitao, SHI Mengmeng, LI Han, WANG Peng, ZHONG Yuanchang

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Aiming at the problems of complex installation, high power supply and maintenance costs of existing transmission line wind deflection/galloping monitoring terminals, this paper proposes a wireless intelligent monitoring scheme based on spacer dampers: MEMS three-axis inertial sensors are embedded in the spacer dampers to obtain the three-directional vibration and torsional responses of the conductors; combined with the compressed sensing framework and the Orthogonal Matching Pursuit (OMP) reconstruction algorithm, the sparsity of data is utilized and a Gaussian random sensing matrix is adopted to realize the reconstruction of the full-line galloping curves. The simulation and experimental results show that: under the given span condition, the sparsity can be adaptively set with the sampling length; when the observation ratio is 10%–20%, high reconstruction accuracy can be achieved, which meets the online monitoring needs of long-span lines. This wireless intelligent spacer damper monitoring scheme provides an engineering feasible path for the real-time monitoring and reconstruction of transmission line wind deflection/galloping
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Requirement traceability oriented hierarchical allocation method for intra- and inter-provincial operating reserve costs

WenXu, ZhouQuan, LiuSheng, XiangMingxu, YangZhifang

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Rational allocation of system operating reserve cost is a crucial mechanism for the electricity market to incentivize market participants to proactively reduce uncertainties. Accurately tracing the impact of market participants on the operating reserve requirement is a prerequisite. The impact on the requirement is closely related to the quantification pattern of the operating reserve requirement. The industrial practices mainly set the operating reserve requirement as the maximum value between the contingency reserve and the net load reserve, which exhibits discrete characteristics. However, existing reserve cost allocation methods do not consider the above characteristic, leading to an unreasonable cost allocation pattern. As a result, the resource allocation efficiency of the electricity market is limited. Furthermore, existing research mainly focuses on the intra-provincial operating reserve. The cost allocation considering the supply and demand of intra- and inter-provincial operating reserve is not explored. To address the above issue, considering the total intra- and inter-provincial reserve costs, this paper proposes a requirement traceability oriented hierarchical allocation method for operating reserve costs. Firstly, a common requirement sharing pattern is proposed to decompose intra- and inter-provincial reserve costs into contingency reserve costs and net load reserve costs, considering the discrete characteristic of the requirement quantification pattern based on the maximum value in industrial practices. Subsequently, considering the superposition characteristic of uncertainties from different categories of market participants, the contingency reserve costs are further allocated based on common requirement sharing, and the net load reserve costs are further allocated based on modified substitution benefit. Case studies based on practical data validate the rationality of the proposed method.
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Vibration Analysis of Elastic Support for Torque Arm of Wind Turbine Gearbox

Hu Zhixin, Song Hailan, Yuan Baogang, Zhu Caichao, Li Chengwu

Abstract: (48) HTML (0) PDF (0.00 ByteKB) (0)

The elastic support is an important component to support the wind power gearbox and absorb the dynamic load of the wind wheel. It is easy to be damaged during the operation of the wind turbine generator system, and its vibration response under the stable operation and variable speed and load conditions needs to be focused. Taking the drive train of a wind turbine generator system with 4MW two-point support as the research carrier, considering the flexibility of the elastic support of the wind turbine gearbox, the rigid-flexible coupling dynamic model of the drive train of the wind turbine generator system is established to study the vibration response of the elastic support under the stable operation of the drive train and variable speed and load conditions, and reveal the vibration characteristics of the elastic support under different working conditions. The results show that the axial vibration of elastic support is dominant when the main shaft is aligned, and the vibration space trajectory is elliptical; The misalignment of the main shaft sharply increases the axial vibration displacement of the elastic support, reaching the peak value 8.099mm at 0.1 ° deflection angle, and the radial displacement peak value caused by 0.05 ° deflection angle due to resonance; The bearing parameter analysis shows that the axial radial displacement of elastic bearing increases linearly with the increase of float bearing clearance, while the thrust bearing only affects the axial direction. Under variable speed and load condition, the vibration mode of elastic support in X/Y direction changes with the turbulence intensity, and the amplitude in Z-direction vibration displacement is related to the wind speed. Frequency-domain analysis shows that the vibration energy is concentrated on the rotational frequency 1 and 2 of the hub, and the coupling between the low frequency load transfer mechanism and the system mode significantly increases the fatigue risk of the elastic support.
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Mechanical Performance of Prefabricated CFST Wind Turbine Tower Joints Based on Arc-Shaped Endplate and Single-Side Bolt Connection

GAO Chunyan, LI Zongyan

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To improve the construction and installation efficiency of wind turbine towers and overcome the residual stress issues of traditional welded joints, it innovatively introduced the concept of detachable design into concrete-filled steel tube (CFST) wind turbine tower joints. Static tests and numerical simulation analyses were performed on four prefabricated concrete-filled circular steel tube (CFCST)-gusset K-joints with arc-shaped end plates and a prefabricated circular hollow section (CHS)-gusset K-joint with arc-shaped end plate. The test results show that all the CFCST-gusset K-joints exhibit two distinct failure modes: web member and gusset plate failures, while the arc-shaped end plates and single bolts are always in good condition. The bearing capacity of the joints is significantly correlated with the failure mode. Based on the verification of the correctness of the finite element model, a parameter expansion analysis of this type of joint had been performed. The results show that the gusset plate-to-web thickness ratio μ and the arc-shaped end plate-to-gusset plate thickness ratio β have significant influence on the failure mode and bearing capacity of the joints. It is suggested that μ ≥ 2 and β ≥ 1.5.
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Design and Energy Absorption Analysis of a New multi-cell Type-H Whip Restraint with openings

HE Zheng, YANG Yuhang, ZHANG Gongye, HU Hongwei, XIAO Liqun

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Two novel H-shaped whip restraints integrating multi-cell configurations with surface perforations were developed to enhance energy absorption and stabilize peak reaction forces. Finite element analysis was conducted using ABAQUS/Explicit to compare mechanical responses between conventional honeycomb H-shaped restraints and multi-cell perforated thin-walled structures under axial/eccentric compression. Results showed the conventional structure exhibited 20% higher initial peak crushing force than new designs, while the 25-cell elliptical-hole configuration demonstrated optimal performance with 21.7% greater total energy absorption. During eccentric loading, the conventional design showed rapid load escalation beyond 120mm displacement, whereas the multi-cell perforated structure maintained stable platform force fluctuations. Crashworthiness tunability was achieved through series-parallel topology optimization of cellular units, enabling directional control of energy absorption via cell quantity adjustment and layered configuration design.
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Optimization and performance analysis of directional heat injection in thermally activated energy-storage composite walls

YANG Yang, GE Yue, CHEN Sarula, XIAO Xiuyi, CHEN Kunyu, CHEN Tianhang

Abstract: (39) HTML (0) PDF (0.00 ByteKB) (0)

To address the capacity mismatch between heat injection and thermal diffusion in thermally activated walls, a design with enhanced heat injection design (ETAW) is proposed for improving energy storage efficiency and energy-saving potential. Dynamic heat transfer modeling was employed to comparatively analyze thermal performance differences among ETAW, conventional thermally activated walls (CTAW), and conventional energy-saving walls (CW). Local sensitivity analysis was conducted to investigate the economic impacts of fin parameters, climate factors, and insulation thickness. Results demonstrate that ETAW significantly outperforms CTAW and CW in dynamic thermal behavior, though performance varies with heat injection modes. Increasing trunk fin size and Branch fin size both effectively reduce ETAW"s total operating energy consumption and costs, with Branch fin size exhibiting more pronounced influence. Selecting smaller inclination angle of branch fin (e.g. 60°) and left-oriented installation can reduce operating costs and energy consumption by approximately 10.9 % and 10.7 % respectively. Insulation thickness shows strong correlations with energy efficiency and economic performance, with recommended reduction rates not exceeding 40 % in severe cold zones and extendable to 60 % in hot summer zones.
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D-RRT-Based Trajectory Optimization for Autonomous Vehicle and VRU Interaction

Xu Ting, Deng Kailong, Liu Wenyu, Lai xinhe, Yang Cong

Abstract: (46) HTML (0) PDF (0.00 ByteKB) (0)

Intersections are high-risk locations for traffic conflicts, where coordinating autonomous vehicles (AVs) with vulnerable road users (VRUs) like pedestrians is critical for safety. To ensure VRU crossing safety and traffic efficiency at intersections, this study proposes a Directional-improved Rapidly-exploring Random Tree (D-RRT) trajectory optimization algorithm based on VRU trajectory prediction. Using the self-collected Weiyang Road Video Dataset (WY-Road Dataset) and the Dalian University of Technology Video Dataset (DUT Dataset), we first identify motion features influencing trajectory prediction, then mathematically model intersection scenarios with constraints. Safety distance models are established for categorized VRU-vehicle interaction scenarios. The proposed D-RRT algorithm improves conventional RRT through directional optimization, with trajectories further refined via cubic spline interpolation. Results demonstrate that compared to RRT, D-RRT reduces trajectory curvature variation by 31.67%, shortens average planning time by 0.1s with better temporal stability. Additionally, the D-RRT algorithm excels in increasing the minimum distance to VRUs and reducing the risk of VRU-vehicle conflicts, ensuring the quality of trajectory optimization.
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Stability of karst landslide based on cusp catastrophe theory

ZHAORuixin, PU Junchi, LIBin, YILianxing, ZHANGDong, ZHANGXiuyu

Abstract: (99) HTML (0) PDF (0.00 ByteKB) (0)

In order to study the variation law of mountain stability in karst area, considering the deterioration of back edge pipeline and sliding surface pipeline, as well as the weakening effect of water on structural plane. Taking the plane sliding of karst mountain as an example, two kinds of geological models and corresponding mechanical models are established, including unconnected and connected karst pipeline. Based on cusp catastrophe theory, deduced the stability coefficient (FOS) and critical stability coefficient (FOS*) of karst mountain under the action of karst pipeline flow, recommended the energy criterion of abrupt instability of mountain in karst area. The results showed that the displacement relationship between the equilibrium point and the critical instability point can indicate whether the mountain is unstable or not; there is one more factor about the stiffness coefficient k in the calculation formula of FOS and FOS* when the karst pipeline is unconnected, revealing that the karst pipeline has a certain effect on the mountain stability; FOS as an important factor affecting the mountain stability is related to the k and m. Through the case study of Jiwei Mountain landslide, it is proved that the energy criterion based on cusp catastrophe theory can better verify the stability of karst mountain with complex sliding surface structure, and can supply the results obtained by limit equilibrium method.
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Numerical Study on the Effects of Turbulence Intensity and Ice Accretion Characteristics on Dynamic Aerodynamic Forces of Transmission Line Conductors

LV Feng, WANG Lin, SUN Pengcheng, ZHANG Yahui, HUANG Xueling, HUANG Xudong, HU Qin

Abstract: (51) HTML (0) PDF (0.00 ByteKB) (0)

Due to the limitations of current studies on the aerodynamic characteristics of iced conductors—which are mostly based on static or uniform flow fields—this paper aims to reveal the nonlinear coupling mechanisms among turbulence parameters (turbulence intensity, mean wind speed) in actual turbulent wind fields, icing morphology (thickness, attack angle), and the dynamic aerodynamic response of conductors, thereby providing a theoretical basis for the anti-vibration design of transmission lines. A dynamic flow field model is constructed using Fluent, and different turbulent environments (turbulence intensity from 0 to 15% and mean wind speed from 1 to 5 m/s) are simulated through pulsating wind speed time-series control. Combined with variations in icing thickness (5 to 20 mm) and attack angle (30°to 45°), the dynamic aerodynamic characteristics of iced conductors are systematically analyzed. The study shows that an increase in turbulence intensity significantly enhances the instantaneous amplitude of aerodynamic fluctuations while suppressing their mean value; when the mean wind speed exceeds a critical value (2 m/s), the mean lift coefficient rebounds while the drag coefficient continuously decreases; when the icing thickness increases to 15 mm, the direction of lift reverses and the drag increases linearly; near an attack angle of 45°, the lift coefficient abruptly reverses while the drag continues to increase. These findings provide a theoretical foundation for analyzing the mechanisms of dynamic aerodynamic instability and for optimizing the anti-vibration design of transmission lines.
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Study on mechanical properties and toughening mechanism of shotcrete by polyformaldehyde fiber admixture

LIU ZHOU, WANG Guangjin, WANG Menglai, LI Shujian, YUAN Mingli, CHEN Qinglin

Abstract: (88) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the current deep roadway support shotcrete there are mechanical properties of low, toughness deficiency poor and other problems, the effects of polyoxymethylene (POM) fiber admixture (0, 5, 7, 9 kg/m3) on the mechanical properties of roadway support shotcrete were analyzed by four-point bending test and SEM technology. The results show that POM fiber can significantly improve the mechanical properties of concrete, of which the flexural strength is most significantly increased (89.46%), compressive and splitting tensile strength are increased by 43.48% and 62.71%, respectively, and the toughness effect is the best when the dosage is 7 kg/m3. In the macro and fine mechanical properties, the residual flexural strength retention rate is more than 30%, which effectively inhibits the development of cracks and reduces porosity, while significantly attenuating the brittle damage characteristics of the material; in the micro scale, the fibers inhibit brittle damage through interfacial frictional energy dissipation and three-dimensional load transfer, and their surface stripe structure enhances the mechanical occlusion as well as the fibers have two forms of pullout and pull-off. The research results can provide theoretical and technical support for POM fiber in the field of tunnel support.
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A privacy-protected distributed economic dispatch in dynamic directed network environments

Lü Qingguo, Han Zefei, Deng Shaojiang, Li Yantao

Abstract: (66) HTML (0) PDF (0.00 ByteKB) (0)

As one of the basic problems of smart grid, economic dispatch problem (EDP) has aroused extensive research interest with the expansion of network scale and the improvement of system complexity. The problem aims to ensure that the overall electricity demand and generating capacity are met while minimizing the overall power generation cost by optimizing the output power of individual generating units. In order to solve the EDP, a new distributed random sleep algorithm is proposed over time-varying unbalanced directed networks. The algorithm incorporates interfering noise in the information transmission process, which effectively protects privacy. Meanwhile, the random sleep strategy ensures that the algorithm has better computational efficiency. In addition, theoretical analysis is also provided to ensure the convergence and privacy of the proposed algorithm. Finally, the effectiveness of the algorithm is demonstrated by simulation experiments.
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Fine-Grained Fake News Detection Based on Textual and User Evidence

WANG HongBin, LI Ye

Abstract: (76) HTML (0) PDF (0.00 ByteKB) (0)

Existing fake information detection methods primarily focus on analyzing textual and structural features, failing to comprehensively consider subtle clues in the propagation process of misinformation (e.g., users supporting articles and posts about articles). Evidence-based reasoning methods can achieve fine-grained modeling of these subtle clues during propagation through complex reasoning techniques, thereby enabling fake information detection. However, evidence is often large-scale, making it highly challenging to perform fine-grained reasoning by considering all evidence. The logical reasoning ability of human thinking can better connect subtle clues and identify the most critical ones. A fine-grained reasoning framework, which better reflects the logical process of human thinking, is proposed to model these subtle clues, thereby shifting toward fine-grained reasoning for fake information detection. Specifically, first, a mutually reinforced claim-evidence graph is constructed based on interactions between text and users to identify key evidence. Second, a prior-aware dual-channel kernel graph network is designed to model subtle differences among evidence. To validate the effectiveness of the proposed method, experiments are conducted on two public datasets. The results demonstrate that the proposed model improves accuracy by 5% and 7.9%, respectively, compared to the best baseline methods.
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Research on kinematics and dynamics similarity theory of mechanism with clearance

DONG Chenhao, JIAN Kailin

Abstract: (78) HTML (0) PDF (0.00 ByteKB) (0)

Elastic mechanisms with clearances have extensive applications in a series of mechanism-based devices such as vehicles, aircraft, spacecraft, robots, and precision machinery. Small-sized mechanisms are of great significance for the research and manufacturing of prototype mechanisms under the guidance of appropriate similarity criteria. Based on the equation analysis method and dimensional analysis method, the kinematic and dynamic similarity criteria of the gap-free mechanism were established, and the dynamic similarity criterion of the gap-free mechanism was obtained. For the rudder surface actuator of the aircraft, physical models with different clearance values were established using the ADAMS simulation software and simulation calculations were carried out. It was found that the change of the similarity coefficient of the clearance would only cause oscillation in the angular velocity output of the mechanism, but would not lead to a corresponding proportional change in the angular velocity, which verifying the research conclusion of the kinematic and dynamic similarity criterion of the mechanism with clearance.
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Analysis of End Friction in Triaxial Tests Using Photogrammetry and Discrete Element Simulation

QIAO Zhibo, MU Chunmei, Zhang Yi, Fan Mingliang, Liu Chunfan

Abstract: (62) HTML (0) PDF (0.00 ByteKB) (0)

Abstract: End friction effects in triaxial tests can lead to overestimation of soil strength. This study investigated the influence of end friction on different regions of the soil specimen (divided into 1/4, 2/4, 3/4, top, and bottom sections based on coded points) using photogrammetry. An end restraint coefficient (β) was introduced to quantitatively analyze the extent of friction effects. In addition, discrete element software PFC was used to simulate and validate the behavior of the specimen under various end restraint conditions.The results show that: (1)The 1/4 region at the center of the specimen is minimally affected by end restraint and exhibits more uniform deformation, which effectively represents the overall strength of the specimen. (2)The results of PFC simulations under unconstrained end conditions align with the photogrammetric measurements. (3)The end restraint coefficient (β) effectively reduces the interference of end friction effects, providing more accurate deformation and reliable strength data for the soil specimen.The proposed method, which uses localized deformation data to mitigate end friction effects, offers technical support for improving the precision and reliability of triaxial test data.
1
A theoretical approach of spatiotemporal data expression in mining models for open-pit coal mine production organization

YUAN Jie, LIU Guangwei, CHAI Senlin, GUO Weiqiang, LEI Jian

Abstract: (90) HTML (0) PDF (0.00 ByteKB) (0)

The production organization of open-pit coal mines represents the final stage in executing production plans, di-rectly influencing whether mining operations can be completed efficiently, rationally, and with the required qual-ity and quantity. The current production organization and management model, which primarily relies on static CAD files combined with production task plans, fails to dynamically and accurately describe the production pro-cess, thus falling short of the requirements for precision mining and refined production management. To address this limitation, this study proposes a multi-factor spatiotemporal data representation method for mining models based on a detailed analysis of the application structure and spatiotemporal evolution characteristics of geological models in open-pit mining production organization. First, to enhance the applicability of geological models in engineering practice, this study introduces the concept and modeling principles of parametric mining models by integrating mining parameters with equipment production capacity. Utilizing Boolean logic-based sequential op-erations, the regular mining model is automatically discretized and decoupled. Second, a hierarchical five-level operational workflow is designed with the mining model as the core data carrier. The spatiotemporal data of the mining model is systematically described across five dimensions: attribute markers, temporal markers, change markers, spatial position sets, and operational equipment sets. Third, leveraging the principles of baseline correc-tion and object-oriented methodologies, a hybrid spatiotemporal data model is proposed for the storage and or-ganization of spatiotemporal data. This model employs different storage strategies for various multi-factor data of the mining model at different time points. Finally, based on the multi-factor spatiotemporal database, a dynamic production plan inversion algorithm is developed. The algorithm enables production plan inversion at specific temporal granularities by dynamically extracting the corresponding multi-factor spatiotemporal information snapshots of the mining model over time. The proposed method provides an effective means of describing the multi-factor spatiotemporal evolution of mining models at different temporal granularities throughout the pro-duction organization process. It provides a theoretical reference for integrating geological foundations, produc-tion planning, and engineering execution to achieve comprehensive and refined control from macro-level pro-duction planning to precise mining design in open-pit mines.
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Simulation of Temperature Characteristics of Avalanche Failure in IGBT Devices

HOU Huachen, LI Hui, YAO Ran, LAI Wei, HU Yinghong

Abstract: (97) HTML (0) PDF (0.00 ByteKB) (0)

Insulated Gate Bipolar Transistor (IGBT) devices, during the Unclamped Inductive Switching (UIS) process, are subjected to extreme high voltage and large current simultaneously, which can easily lead to avalanche failure. Avalanche ruggedness is a measure of the device’s ability to withstand such extreme conditions. This paper investigates the failure mechanisms and avalanche robustness of IGBT devices under overvoltage conditions, both in static avalanche and dynamic avalanche during the turn-off process, through theoretical analysis, analytical modeling, and numerical simulation. Furthermore, the influence of temperature on the dynamic and static avalanche breakdown characteristics is studied. The results show that the causes of both dynamic and static avalanche breakdown are the internal electric field of the device reaching the avalanche critical breakdown field, triggering the avalanche multiplication effect of internal carriers. The occurrence of avalanche multiplication does not necessarily mean device failure. However, when the energy generated during the avalanche voltage maintenance phase exceeds the device’s avalanche ruggedness, the device undergoes destructive avalanche breakdown failure. The current density distribution inside the device changes compared to before failure, the parasitic transistor turns on, and gate latch-up occurs, making the device unable to turn off normally. Increased temperature leads to a higher avalanche breakdown voltage, shorter avalanche voltage maintenance time, increased power dissipation during avalanche, and reduced avalanche ruggedness, affecting the turn-off reliability of the device.
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An Optimization Method for Packaging Parasitic Inductance in SiC Power Modules under Reverse Coupling

SHU Bicheng, LIAO Xinglin, WANG Xiao, LONG Haiyang

Abstract: (94) HTML (0) PDF (0.00 ByteKB) (0)

Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) power modules are highly sensitive to packaging parasitic inductance in high-frequency and high-speed switching applications. Excessive parasitic inductance can cause voltage overshoot, current oscillation, increased switching losses, and intensified electromagnetic interference. To address this issue, this paper proposes an optimized power terminal structure based on reverse coupling, which effectively reduces packaging parasitic inductance while maintaining compatibility with standard module layouts. By redesigning the power terminal geometry, anti-parallel current paths are formed between adjacent conductors to enhance mutual inductance cancellation and suppress the total inductance. Simulation results show that the packaging parasitic inductance decreases from 21.86?nH to 10.67?nH after optimization, and the new structure also exhibits good performance in insulation withstand voltage and thermal stress. To verify the effectiveness of the proposed method, a prototype was fabricated and tested. Double-pulse testing yielded a value of 12.67?nH, and vector network analyzer (VNA) measurements indicated 11.61?nH, representing a 46.9% reduction compared with the standard structure. These results confirm the feasibility of the proposed method in engineering applications and provide a new approach for developing low-cost, low-inductance packaging for SiC power modules.
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Ideal SH-ADD model informed sliding mode control of semi-active suspension system for vehicles

ZHANG Hong, ZOU Hantong, YE Lei, CHEN Jianhua, CHEN Hao, HE Yansong

Abstract: (115) HTML (0) PDF (0.00 ByteKB) (0)

The semi-active suspension system plays a crucial role in improving the ride comfort and handling stability of vehicles. To maintain the stable sliding mode of vehicle semi-active suspension system and avoid oscillations caused by the suspension control force, this paper introduces the ideal Sky-Hook-Acceleration Driven Damper (Ideal SH-ADD) system as the reference model. Besides, the corresponding responses are set as the reference for the semi-active suspension control. The rationality of the reference model is verified through frequency-domain analysis. Furthermore, the error dynamics model between the actual controlled system and the ideal model is established, which considers the constraints of actuator force and employs a reaching law to regulate the chattering phenomenon during the sliding mode control. Finally, the Adams/Simulink co-simulation platform is built to verify the control performance on ISO-B class random road. The results indicate that, compared to the passive suspension and traditional SH-ADD control, the acceleration of vehicle sprung mass is significantly optimized by 44.49% and 8.29%, respectively.
1
中图分类号:V443??????? 文献标志码:A

Luoxiaowu, Lipu, Zhouqinghua, Chenjiajun, Zhangqiang, Liuyanmin, Zhuhao

Abstract: (82) HTML (0) PDF (0.00 ByteKB) (0)

This work proposes a micromechanical model to address the electrical contact problem between a spherical indenter and a homogeneous half-space, considering the coupling competition between frictional heat and Joule heating. Unlike methods that determine undetermined coefficients in the general solution of partial differential equations, this research leverages Green"s functions and Eshelby tensor theory to reveal the transfer function relationships among current, heat flux, and stress, providing an efficient approach for solving sequential electro-thermal-mechanical multiphysics coupling problems. Through integral transformations of complex potential functions, explicit frequency-domain solutions for thermal and elastic fields are derived. The model is validated by finite element simulations, systematically investigating the effects of speed, load, voltage, current, and indenter radius on the coupling competition between frictional and Joule heating. This work offers new thermal management insights for minimizing the maximum temperature rise.
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Study on the preparation and mechanical properties of self-reinforced anisotropic hydrogels based on poly(vinyl alcohol) hydrogel fibers

MA Yingli, XIANG Chenxing, NING Huiming

Abstract: (89) HTML (0) PDF (0.00 ByteKB) (0)

A study on the mechanical property enhancement and industrial production challenges faced by hydrogels in practical applications is carried out in this study. Due to the limitations of traditional isotropic hydrogel toughening methods and the shortcomings of common fiber reinforcing material systems, a new method of hydrogel fiber preparation is proposed. A commercial water-soluble polyvinyl alcohol (PVA) yarn was impregnated with a glycerol-containing aqueous solution and then subjected to a freeze-thaw cycle to produce PVA hydrogel fibers, and its tensile properties were tested. The fibers were then composited with a PVA hydrogel matrix to prepare self-reinforced anisotropic hydrogels, and the effects of the fiber volume fraction, matrix PVA content and other factors on their mechanical properties were investigated in depth. The results showed that the fiber properties of PVA hydrogel could be significantly improved by optimising the glycerol content, such as tensile strength of 54.7 MPa at 80 wt% glycerol mass fraction, and the tensile strength of self-reinforced anisotropic hydrogel was maximum at 6.2 MPa at 16% fiber volume fraction, and the mechanical properties could be improved by increasing the PVA content of the matrix. At the same time, the superelastic intrinsic model using this kind of hydrogel was
1
Parameters identification of extended debye model of transformer based on hybrid characteristics of time-frequency domain spectrum

Lin Zhi-yong, Su Ruo-hang, Deng Dong-ping, Chen Xin-hui, Zhang Da-wei, Zhang Da-min

Abstract: (49) HTML (0) PDF (0.00 ByteKB) (0)

In view of the problem that the long measurement of recovery voltage polarization spectrum and frequency domain dielectric spectrum affect identification efficiency of the extended Debye equivalent circuit parameters of transformer oil-paper insulation system, this paper proposes a novel identification method. At first, this paper proposes characteristics of hybrid time-frequency dielectric spectrum, which consist of the recovery voltage polarization spectrum characteristics under short charging time and small amount of frequency dielectric spectrum characteristics. Then, based on these proposed characteristics, using multi-objective particle swarm optimization (PSO) to identify equivalent circuit parameters. At last, compare the test time of the proposed method with the on-site testing. The results show that: equivalent circuit parameters of the extended Debye constructed by using characteristics of the hybrid time-frequency dielectric spectrum can effectively restore the complete recovery voltage polarization spectrum and frequency domain spectrum which field measured. The coincidence between the calculated and measured values of the two kinds of dielectric spectrum is above 95%. Moreover, the new method can reduce the test time by 61% compared to the recovery voltage measurement alone and by 46% compared to the frequency domain spectrum alone. The new method not only ensures the accuracy of parameter identification, but also greatly reduces the test time and improves the test efficiency. It is of great significance to the application and popularization of dielectric spectrum measurement technology in transformer on-site insulation detection.
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Research on Transmission Line Galloping Monitoring Technology

WU Haitao, SHI Mengmeng, LI Han, WANG Peng, ZHONG Yuanchang

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The outbreak frequency of the galloping caused by wind deflection of transmission lines is relatively high, which seriously affects the normal and stable operation of the power system and brings significant losses to the national economy. Therefore, the real-time online monitoring of the galloping of transmission lines has always been a research hotspot in this field. Starting from the causes of the galloping of transmission lines, this paper discusses the online monitoring technology and system performance of the galloping of transmission lines, analyzes the commonly used online monitoring methods for galloping, related research and existing problems, and summarizes the difficulties of the current online monitoring technology for the galloping of transmission lines. A fusion monitoring method of "MEMS vibration sensor + BD differential positioning" is proposed. With the communication networking mode of the integration of WSN/GPRS/BD three networks, a real-time online monitoring network platform for the galloping caused by wind deflection of large crossing transmission lines with the integration of sky, ground and space based on Beidou communication is established to achieve the real-time monitoring of the galloping of transmission lines, which has practical guiding significance for carrying out the research on the real-time online monitoring of the galloping of transmission lines.
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Improved Yolov8 Lightweight Helmet Wearing Detection Algorithm Based on Improved YOLOv8 for Complex Construction Scenarios

Ding Wanqin, Li Meng, Shi Zihao, Li Haibing, Pang bo, Li Xiaohu, Meng Xiaodong

Abstract: (98) HTML (0) PDF (0.00 ByteKB) (0)

Safety helmets are crucial to the safety of construction workers, However, there is still a phenomenon that the construction workers do not wear safety helmets all the time.Current helmet detection algorithms have the problems of high computational complexity and low detection accuracy in complex construction scenarios, so there is an urgent need for a real-time high-precision method to detect helmet wearing in complex construction scenarios.In this paper, we propose a lightweight helmet detection algorithm based on the improved YOLOv8, which firstly replaces the YOLOv8 backbone network with MobileNetv4 and retains the SPPF part; secondly, replaces the traditional depth-separable convolution with GSconv in the neck network, replaces the CSP network layer with GhostNet, and fuses the GhostBottleneck and C2f modules, and introduces the S2f module.C2f module and introduce SENet to optimise C2f; finally, the EMA module is introduced in the head network.The experiments show that compared with the six models such as Faster R-CNN and YOLOv5s, the improved YOLOv8 model improves significantly in terms of accuracy, recall, mean average precision, computation volume and frame rate, etc. The accuracy rate of 90.12%, the recall rate of 89.27%, and the mean average precision value of 84.28% meet the requirements of safety for construction workers on construction sites, and it is suitable for the actual construction sites.environment, improving construction safety.
1
A Novel Broadband Patch Antenna

LI sheng-zhe, WU Zhe, YUN Yu, MA Ling-ku

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A wideband microstrip patch antenna using an L-shaped parasitic structure was developed to address the inherent narrow bandwidth limitation of conventional microstrip antennas. The antenna consists of a main radiating patch and L-shaped parasitic patches, with an overall size of 0.83λ?×0.83λ?×0.083λ?, where λ? is the free-space wavelength at the center frequency of 5 GHz. The main patch operates in the fundamental transverse magnetic (TM10) mode. Multiple resonant modes are excited through electromagnetic coupling with the parasitic elements to broaden the bandwidth. A Rogers 5880 substrate with a relative permittivity of 2.2 and a loss tangent of 0.0009 was used to reduce the quality factor. A 180-degree out-of-phase differential feeding scheme was applied to suppress pattern distortion. Simulation results show that the antenna achieves a voltage standing wave ratio (VSWR) below 2 from 3.6 GHz to 6.6 GHz, corresponding to a 60% relative bandwidth—six times wider than that of traditional designs. A peak gain of 9.8 dBi occurs at 6.2 GHz, with gain variation less than 1.5 dB across the operational band. The radiation pattern maintains main beam deviation within 5 degrees and cross-polarization levels better than -15 dB over 3.6–6.3 GHz, reaching as low as -38 dB at the center frequency. This single-layer design achieves wideband and high-gain performance, making it suitable for broadband wireless communication systems such as fifth-generation (5G) mobile networks and Wi-Fi.
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High-Dynamic Noise Robust Speech Recognition Model for Intelligent Inspection in Wind Farms

LI Yuan, Zhang Yuechao, Feng Jiangzhe, Zhou Jiwei, Zeng Fanli, Li Jun, liaoyong

Abstract: (98) HTML (0) PDF (0.00 ByteKB) (0)

Existing speech recognition technologies are confronted with issues of low speech recognition accuracy, difficulty in recognizing specialized terminology, and limited computational power of terminal devices in the high-dynamic noise environment of wind farms. To address the issues, this paper proposes a High-Dynamic Noise Robust Speech Recognition Model (HDNR-SRM). The model integrates Cross-Parallel Transformer Neural Networks (CPTNN) and Enhanced Wav2Vec 2.0 (EW2). It employs a time-domain speech enhancement model based on CPTNN to generate dynamic masks for separating speech from noise; finetunes the quantized codebook of the EW2 model based on the wind farm inspection corpus to improve the discriminative power of the embedded representations of specialized vocabulary; and reduces algorithm complexity through lightweight designs such as shared feature encoders and cross-parallel attention mechanisms, significantly reducing the model's parameter count to adapt to the real-time computational requirements of terminal devices. Experimental results show that in simulated high-dynamic noise and actual high-dynamic noise environments with a signal-to-noise ratio of -10 dB, the character error rates of HDNR-SRM are 16.8% and 18.5%, respectively, which are 6.4%-16.7% and 7.1%-17.2% lower than those of the comparison models; the sentence error rates are 41.3% and 45.2%, respectively, which are 8.9%-23.4% and 7.9%-23.1% lower than those of the comparison models. In wind farm inspection scenarios, after 6000 hours of on-site verification, the model's recognition accuracy for specialized terminology reaches 95.4%, increasing work efficiency by 38.5% and reducing the manual recording error rate by 42.7%. The model exhibits significant advantages in noise robustness, domain adaptability, and lightweight deployment, providing a reliable technical support for the intelligent inspection of wind farms.
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Enhanced Deblurring Target Detection Method for UAVs Based on Improved DeblurGANv2

SHEN CHAO, HUANG ZHENG, Chengling Jiang, Minghui Zhang, Ma Junzhou

Abstract: (119) HTML (0) PDF (0.00 ByteKB) (0)

Wind disturbances and body vibrations often cause image blurring in unmanned aerial vehicle (UAV) inspections, reducing target recognition accuracy. This study developed an enhanced UAV deblurring and target detection method based on an improved DeblurGANv2. A Haar wavelet-based image blur detection method was introduced, achieving high-precision identification of blurred regions through multi-level grayscale decomposition and edge feature extraction. An improved DeblurGANv2 network integrating an efficient channel attention module and modulated deformable convolution was designed to extract and restore blurred features effectively. Cross-channel feature correlation and an adaptive sampling strategy improved feature extraction and reconstruction accuracy. Experimental results show that the proposed method effectively restores edge structures and fine details in motion-blurred UAV images. Compared to DeblurGANv2, the restored images achieve a 37.6% increase in peak signal-to-noise ratio and an 11.4% improvement in structural similarity. For blurred image target detection, recognition accuracy improves by 18%, and recall increases by 30% over conventional methods.
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Zhao Yang12 , Hu Chunqiang1,Ma Muchen12

zhaoyang, huchunqiang, mamuchen

Abstract: (55) HTML (0) PDF (0.00 ByteKB) (0)

In order to solve the problem that the traditional comfort evaluation method relies on subjective questionnaires to meet the needs of real-time and objectivity, a comfort prediction method integrating variational inference and AutoFormer+ was proposed to realize the real-time and objective evaluation of driver"s comfort. The comfort prediction method based on variational inference takes the EEG signal and sitting joint angle as inputs, and the subjective score of sitting comfort as the label, and the AutoFormer+ algorithm optimizes the attention module by introducing the frequency domain enhancement module to complete the comfort classification of the driver"s EEG data. In this paper, experiments are carried out on the static test dataset of real vehicles, and the proposed algorithm achieves better performance than the traditional method in the comfort classification task, with an accuracy of 0.95, which is 0.5% higher than that of the baseline model.
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Optimization of autonomous vehicles trajectories under abnormal events in mixed traffic flow

ZHANG Luning, WANG Jingsheng

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Aiming at the imbalance between efficiency and safety of cooperative lane changing of self-driving vehicles triggered by abnormal events in mixed traffic flow, this paper proposes a trajectory optimization model based on Multi-Intelligent Dueling Double-Depth Q-Network (MAD3QN). The model dynamically couples global traffic efficiency and local safety indexes through a hierarchical reward mechanism that combines a centralized experience pool-sharing strategy to eliminate strategy oscillations and information silos in multi-vehicle coordination, and the model effectively suppresses Q over-estimation bias by separating the state value function from the dominance function and introducing a dual Q learning asynchronous update mechanism. The study builds a Carla-SUMO joint simulation platform, integrates microscopic driving behavior modeling and physical engine interaction, calibrates the key parameters of the follow-along model; and designs dynamic and abnormal scenarios, such as accidental lane occupancy and emergency obstacle avoidance, to fill in the gap of the research on the active control of self-driving vehicles in unsteady traffic flow. The experimental results show that compared with the advanced benchmark model, the multi-intelligent body dueling double deep Q-network model has significantly improved the average reward value under different traffic flow densities, realizing the Pareto optimization of safety and access efficiency, and providing an innovative framework of both robustness and generalization ability for the collaborative decision-making of self-driving vehicles under abnormal events.
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A data distribution-aware full integer quantization training framework

ZHAO Xin, LIU Qiang

Abstract: (82) HTML (0) PDF (0.00 ByteKB) (0)

To improve training speed of deep neural networks and reduce resource consumption on edge devices, quantization training methods have been extensively studied. Compared to floating-point or mixed-precision approaches, full integer quantization offers significant potential in edge training scenarios due to its strong hardware compatibility and high computational efficiency. However, conventional integer quantization struggles to adapt to the dynamic changes of data distributions during training, often leading to significant accuracy loss. To address this issue, a data distribution-aware full integer quantization training framework is proposed, which employs a piecewise quantization method to accurately handle long-tailed data distributions and incorporates an adaptive search method to dynamically adjust quantization parameters based on data distributions. Experimental results for training ResNet models on multiple datasets show that the accuracy loss is no more than 2.44% compared to the floating-point training. Compared to the existing integer training methods, the proposed framework reduces the accuracy loss by up to 90.61%. Furthermore, the framework is deployed on an FPGA, and experimental results demonstrate that, compared to the floating-point training framework, the proposed framework saves 27% of memory resources, 53% of DSP computation resources, and reduces execution time by 53%.
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Failure mechanism analysis of silicon carbide MOSFETs in Tesla electric vehicles

Jiang Huaping, Tang Lei, Li Xinxin, Yang Han, Wang Ze, Yang Shuo, Li Yao, Hu Haowei, Liao Ruijin

Abstract: (132) HTML (0) PDF (0.00 ByteKB) (0)

The dispersive threshold voltage drift in silicon carbide metal-oxide-semiconductor field-effect transistors (MOSFETs) severely impacts their reliability in applications. The Tesla Model 3 recall incident highlighted that the "rear motor inverter power semiconductor components" might have "minor manufacturing variations," which could lead to inverter failure over time, resulting in the inverter"s inability to control current properly. This paper conducts a systematic study on the recall event from two perspectives: device intrinsic differences and circuit loop parameter variations. The intrinsic differences in devices may cause the threshold voltage dispersion to increase with prolonged stress time, thereby exacerbating current sharing issues. Additionally, variations in parasitic inductance in the drive and main circuits can also worsen current sharing. The research demonstrates that both device intrinsic differences and circuit loop parameter variations can influence the threshold voltage drift dispersion, leading to deteriorated current sharing and ultimately causing system failures.
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Research on trajectory tracking based on the dynamic characteristics of vehicle vertical and horizontal coupling

WenHe, chenyong, LiHong Qiu

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The trajectory tracking of autonomous vehicles is closely related to vehicle motion control, which determines whether the vehicle can effectively follow the planning instructions of the decision-making layer and correctly output the control instructions of the drive and steering actuators according to the dynamic characteristics of the vehicle. A two-degree-of-freedom vehicle dynamics model was established, and a model predictive control architecture based on vertical and horizontal coupling dynamics was proposed by using the adaptability of Model Predictive Control (MPC) in a complex nonlinear and multi-constraint environment, in which the upper-level controller accurately adjusted the longitudinal speed and acceleration to ensure that the vehicle ran along the expected speed trajectory. The lower controller tracks the lateral trajectory and realizes the efficient tracking and control of the planned path of the vehicle by accurately controlling the front wheel rotation angle. The common obstacle bypass scenarios of automobiles are set up for simulation tests, and the proposed strategy is compared with the classical Proportional-Integral-Derivative (PID) and Linear Quadratic Regulator (LQR) controls, and the real vehicle experiments are carried out. The results show that the proposed strategy shows more stable and accurate control performance in different scenarios, which can improve the trajectory tracking accuracy of autonomous vehicles, optimize the control smoothness and improve the ability of vehicles to adapt to complex traffic scenarios.
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Precision degradation prediction method of CNC machine tools based on meta-action unit

ran yan, wang qin, lin yin

Abstract: (72) HTML (0) PDF (0.00 ByteKB) (0)

To accurately predict the precision degradation of CNC machine tools and ensure machining quality, we propose a precision prediction method based on "function-motion-action". The method starts from meta-action unit components. It quantifies error propagation using both adhesive wear and abrasive wear models. We establish accuracy degradation functions by analyzing geometric and kinematic relationships. The machining accuracy evolution patterns are derived through multi-body system theory and homogeneous coordinate transformation matrices. This method achieves reliable accuracy prediction without requiring actual machining data. In experiments on a Nanjing CNC lathe, the mean prediction error was 4 μm. This result demonstrates better interpretability and accuracy than conventional methods. This method offers a theoretical foundation and practical solution for maintaining CNC machine tool accuracy.
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Research on longitudinal and lateral coordinated stability control of distributed electric vehicles under variable speed limit conditions

zhaoshifeng, wangwenjie, shuran, lili, shuhongyu

Abstract: (68) HTML (0) PDF (0.00 ByteKB) (0)

To address the inadequacy of traditional constant-speed control methods in adapting to extreme mountainous conditions, this paper proposes a variable-speed coordinated longitudinal-lateral control strategy based on the coupling characteristics of vehicle dynamics. The strategy adopts a hierarchical control structure: the upper layer designs a steady-state evaluation model to provide an accurate decision-making basis for the middle and lower layer controls; the middle layer primarily utilizes a two-level Model Predictive Control to coordinate potential conflicts between longitudinal four-wheel slip rates, lateral Active Front Steering and Direct Yaw Control, and outputs the total driving torque and yaw moment; the lower layer employs Weighted Least Squares to optimally distribute the obtained torque according to the vehicle's operating state. Finally, a simulation model of the designed coordinated control strategy was established based on the Simulink and CarSim simulation platforms, and various complex road conditions were simulated for verification. The results demonstrate that this control strategy can significantly improve the driving stability of distributed electric vehicles under variable-speed extreme conditions.
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Generation of autonomous driving simulation test cut-in scenario library considering the static characteristics of vehicles

zhang xin hao, wang jing sheng, han feng chun, wang xuan, miao ze lin

Abstract: (111) HTML (0) PDF (0.00 ByteKB) (0)

To meet the demand for test scenarios in autonomous driving simulation testing, this study proposed a method for generating a simulation test scenario library that considers the static characteristics of cut-in vehicles. This research focused on highway lane-change cut-in scenarios, developing a logical scenario model that integrates motion information and static characteristics of cut-in vehicles, based on lane-change cut-in data from the highD dataset. A multi-class Gaussian mixture model constructed the joint probability density function of the logical scenario model parameters. The adaptive importance sampling (AIS) algorithm was utilized as the sampling method, and a time-to-collision (TTC) weighting function was introduced to formulate the scenario library generation method, which enabled the generation of a simulation test scenario library according to specific requirements. Experimental results indicate that, in comparison to traditional Markov Chain Monte Carlo and importance sampling methods, the AIS-based scenario library generation method achieves a reduction in the jensen-shannon divergence between the scenario parameter distribution and the original distribution by 65.24% and 79.72%, respectively, and results in a reduction in the number of effective test scenarios by 96.22% and 90.37%, respectively. The proposed method ensures comprehensive coverage of scenario generation while enhancing testing efficiency. Moreover, by adjusting the TTC weighting function, the method increases the proportion of high-risk test scenarios, thereby providing an adequate number of high-risk scenarios for autonomous driving testing, fulfilling diverse testing requirements.
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Fusion of Multi-Source Heterogeneous Data for Power Consumption Prediction and Analysis of CPE Push Bench Mill Machine

YAN Xiuyin, LI Yang, XUE Yuezhao, ZHAO Shanxi, TA Hao

Abstract: (73) HTML (0) PDF (0.00 ByteKB) (0)

In the hot rolling process of seamless steel pipes, the energy consumption management of the CPE push bench mill faces challenges, primarily due to the difficulty in extracting feature information from multi-source heterogeneous data such as equipment and process parameters, which in turn affects the accuracy of power consumption prediction. To address the issue of high-dimensional, nonlinear, and time-varying features in power consumption prediction, this paper proposes a prediction model that integrates multi-source heterogeneous data. The model first combines Convolutional Neural Networks (CNN) for spatial feature extraction. Then, a Transformer encoder is used for modeling temporal features. Finally, the data fusion is achieved through a Cross-Attention mechanism (CA). By preprocessing, feature extraction, and fusion of historical data from actual production, a power consumption regression prediction model is established. Experimental results show that the proposed model significantly outperforms traditional methods, with the coefficient of determination (R2) exceeding 98%. This research provides effective technical support for the energy consumption management of the CPE push bench mill and has high engineering application value.
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Study on effects of gradation and needle sheet content on mechanical behavior of shallow metamorphic SLATE asphalt mixture

REN Song, CHEN Wenjing, LI Meikang, ZHANG Chuang, CHEN Zheng, LONG Nengzeng

Abstract: (65) HTML (0) PDF (0.00 ByteKB) (0)

In order to explore the influence of different grade composition and sheet content on the mechanical properties and damage constitutive relationship of shallow metamorphic SLATE asphalt mixture, uniaxial compression test was carried out to evaluate the mechanical response and failure mechanism of shallow metamorphic SLATE asphalt mixture under different grade composition and sheet content combined with non-destructive testing technology. The results show that the median AC16-B has good mechanical properties and the content of pin-like particles should be less than 10%. The failure form of the sample is "thin at both ends and thick in the middle". Tensile failure is the main failure mode and shear failure is the secondary failure mode for asphalt mixtures with different proportions. With the increase of strain, the total damage variable increases gradually, and the growth rate of damage variable decreases gradually with the increase of needle flake content. The formulation design of shallow metamorphic SLATE asphalt concrete is studied and optimized, which provides a template for rational utilization of stone resources.
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Discrete Dislocation Dynamics Simulation of Fracture Characteristics of Nickel-Based Single Crystal Under Load Relaxation Conditions

ZHANG Qifeng, SUN Fengwei

Abstract: (89) HTML (0) PDF (0.00 ByteKB) (0)

Using a two-dimensional discrete dislocation dynamics and finite element coupling method, numerical simulations were performed on the dislocation evolution and fracture behavior of FCC structured nickel-based single crystal under loading-relaxation-reloading conditions. The model comprehensively considers mechanisms of dislocation nucleation, slip, and annihilation, achieving autonomous crack evolution through the dynamic coupling of dislocations and damage fields without the need to preset the expansion path. The simulation results show that the relaxation process can effectively reduce stress concentration around the crack tip, delay crack initiation, promote crack path deflection and multiple slip system activation. Quantitative analysis indicates that the strain energy release characteristics during the relaxation process is positively correlated with the initial dislocation density, with high-density dislocation systems exhibiting a faster energy equilibrium process.
1
Evaluation and analysis of the impact of subsystem based attacks on the network layer of automotive cyber physical systems

liujingyu, xiaxiaofeng

Abstract: (97) HTML (0) PDF (0.00 ByteKB) (0)

Modern vehicles are becoming increasingly automated, and while their internal CAN network provides connectivity, it also offers opportunities for cyber attacks. Vehicle safety is a fundamental issue in the study of vehicles, and only with sufficient understanding of the impact of attacks can more targeted protective measures be developed to better protect vehicle safety. A subsystem based network attack impact assessment model is proposed to quantitatively evaluate the impact of attacks on the CPS network layer of automobiles. This model measures the impact of attacks on subsystem buses and nodes from two dimensions: availability and integrity. The model was used in the attack experiment to calculate the impact of the attack, verifying its effectiveness and enabling quantitative evaluation of the impact of the attack.
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Design of Magnetic Resonance Logging Probe Based on the Method of Partial Element Equivalent Circuit

LI Tao, XU Zheng

Abstract: (87) HTML (0) PDF (0.00 ByteKB) (0)

Accurate calculation of the alternating-current (AC) impedance of radio-frequency (RF) coils is essential for optimizing the performance of magnetic resonance logging probes. The flexible printed circuit board structure of the probe coil, characterized by a large disparity between thickness and lateral dimensions and its integration with magnetic core materials, makes it difficult to apply conventional finite element methods effectively. To address the low accuracy in electromagnetic parameter computation, a modeling approach based on the partial element equivalent circuit (PEEC) method was proposed by introducing magnetization strength as a key variable. Tetrahedral mesh discretization and vector basis functions were used to accurately model the irregular probe structure. An equivalent circuit model of the magnetic core was established, and the PEEC network of the coil-core composite structure was subsequently derived. Numerical simulations and experimental validations were conducted over the frequency range of 0.1 ~ 2?MHz. The results show that the calculation errors of AC resistance and reactance are less than 5.10 % and 3.24 %, respectively, and are consistent with measured values. Compared with Q3D simulation results, the resistance error was reduced by 30 %, confirming that the proposed model achieves high accuracy in simulating irregular coil-core composite structures and provides reliable support for electromagnetic modeling and performance evaluation of complex magnetic resonance logging probes.
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Mechanism and Influencing Factors of Repetitive Short-Pulse Discharge in Water Micro-Gap

Li Xiandong, Zheng Weiyang, Zhao Zixiang, Cao Jun, Zhu Zixuan, Fu Boya

Abstract: (94) HTML (0) PDF (0.00 ByteKB) (0)

Using high-speed photography and synchronized electrical parameter measurements, we investigated the repetitive discharge evolution characteristics of rod-rod electrode structures in water. The research revealed that the discharge process divides into three typical stages: liquid phase disturbance development, bubble colony evolution, and breakdown with bubble pulsation. Liquid phase disturbances expand toward the gap center under electric field and Joule heating effects; micro-bubbles form, expand, and then collapse into bubble colonies; discharge preferentially occurs inside bubbles, and after breakdown, bubbles exhibit "expansion-collapse-re-expansion" pulsation characteristics. Experiments show that discharge voltage (4-8kV), pulse width (2-12μs), and pulse frequency (20-2000Hz) all correlate negatively with the evolution rate of gap equivalent resistance and repetitive pulse withstand times. Higher discharge voltage accelerates liquid phase disturbance expansion; increased pulse width extends energy injection time and promotes bubble generation in the disturbed phase; high-frequency conditions promote heat and micro-bubble accumulation in the gap and accelerate the breakdown process, while low-frequency conditions inhibit cumulative effects due to complete recovery of the water medium.
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Time-Optimal Trajectory Planning for PMSM Servo Systems under Near-Limit Dynamic Constraints

LIANG Li-yuan, LI Hui, XIANG Xue-wei, ZHOU Hao, YUAN Bin

Abstract: (89) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the problem that the traditional servo - trajectory planning methods for permanent - magnet synchronous motors (PMSMs) fail to fully utilize the fast performance of the motors under the constraints of rated design, a time - optimal trajectory planning method under the constraints of the short - time overload dynamic feasible region is proposed. Firstly, based on the relationship between the motor"s loss power and motion parameters such as speed and acceleration, the trajectory equation that minimizes the motor"s loss during the servo process is derived using the Pontryagin"s maximum principle. Then, by combining the loss power (current) and bus voltage constraints, the dynamic feasible domain of the servo motor system is reconstructed, and a method for solving the coefficients of the time-optimal trajectory equation that adapts to different angular paths is proposed. Finally, an experimental platform for the servo motor system is set up, and the servo response speeds under the trapezoidal curve trajectory with field-weakening control and the proposed strategy are compared. The experimental results show that the trajectory planning method proposed in this paper outperforms traditional trajectory planning methods in terms of servo response speed under different angular path conditions, saving 6.7% to 9.05% of the positioning time.
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Spatio-temporal dynamic spectral diagnostic study of laser-sustained high-pressure xenon plasma

SUN Fuli, MA Xiao, YANG Qi, WANG Licheng, LI Jie, XIONG Qing

Abstract: (176) HTML (0) PDF (0.00 ByteKB) (0)

Laser-Sustained Plasma (LSP) has been widely used in semiconductor wafer defect detection by realizing electrode-free energy coupling through the inverse bremsstrahlung absorption mechanism, which has the advantages of wide spectral range, high brightness and long lifetime. To further clarify the microphysical mechanism of LSP, the dynamic evolution law of high-pressure xenon LSP and the spatial distribution of its electronic parameters were systematically investigated by high-speed imaging and spectral diagnostic techniques. The results show that the plasma morphology shows axial expansion dominated “droplet-like” evolution with the increase of laser power. The position and intensity of plasma centroid oscillate at a specific frequency, and the frequency of the oscillation decreases with the increase of laser power. The electron density and electron temperature in the plasma core region increase by 34.2% and 4.3% with the laser power increasing from 60W to 120 W, respectively. However, the electron parameters show a saturating trend or even a slight decrease with further increase in laser power.
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Reduced-scale modeling method and tests for dynamic responses of bundle conductor lines after ice-shedding

ZHOU Xinrui, YAN Bo, LI Jin, HUA Ming, FENG Dongyue, GAO Yingbo, DENG Huachao

Abstract: (72) HTML (0) PDF (0.00 ByteKB) (0)

Based on the principle of similarity, a reduced-scale modeling test method for dynamic responses of twin-bundle conductor lines after ice-shedding is proposed. The simulation of ice-accretion and ice-shedding on sub-conductors of bundled conductors was achieved. A reduced-scale modeling test platform for dynamic responses of twin-bundle conductors after ice-shedding was established, which can be used to measure the in-plane, out-of-plane and torsional motions of the conductor after ice-shedding, and the time histories of conductor tension and the longitudinal, vertical, and horizontal components of reaction force at hanging points. Reduced-scale modeling tests were conducted for a typical twin-bundle conductor line, including partial ice-shedding and unzipping ice-shedding from a single sub-conductor, and asynchronous ice-shedding from the two sub-conductors. The variations of jumping height, lateral swing, torsion angle and tension of the conductor, and the reaction force at the hanging point versus time were measured. The proposed method provides an important means for deicing design and artificial ice-shedding research of bundle conductor transmission lines.
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Analysis and Study on the Stability of Dissolved area of Glauberite Mined by Water-soluble Method in a Mine

huanggun, qinzhenyang, yaojingming

Abstract: (116) HTML (0) PDF (0.00 ByteKB) (0)

This investigation examines stability challenges in dissolution zones using chamber solution mining at Pengshan Tongle glauberite mine. Through integrated laboratory leaching experiments and FLAC3D finite element modeling, we systematically analyze volume variations of dissolved materials and establish 3D numerical simulations to characterize stress fields, displacement patterns, plastic zone distributions, and surface subsidence. Experimental data reveal that dissolution shrinkage increases proportionally with glauberite content and inversely with ore particle size. Numerical simulations demonstrate: (1) Dissolution contraction ratio critically influences zone stability; (2) Post-leaching bodies exhibit 3.25MPa vertical stress versus 13MPa in intact columns; (3) Roof-connected scenarios show 7mm roof subsidence (7.7mm surface), while non-connected cases display 37.7mm roof displacement (34.5mm surface). The results confirm that roof-connected leached material maintains effective support, ensuring overall stability, whereas non-connected conditions pose potential risks. These findings provide crucial insights for ensuring long-term operational safety in evaporite mining engineering.
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Research on Value Traceability Methods and Metrological Calibration Devices for Digital Image Correlation Methods

WU Yu, YUAN Jing, WANG Lifang, XUE Rui, TANG Yiwen

Abstract: (68) HTML (0) PDF (0.00 ByteKB) (0)

Digital image correlation method currently suffers from inadequate systematic calibration methods and an incomplete metrological traceability system. To address these technical challenges, this study proposes a novel calibration method based on laser interferometry, integrated with a custom-designed optical system for local deformation measurement. Through finite element simulations, we systematically investigated the stress stiffening effect in strain plates under tensile loading. A coupled thermo-mechanical deformation model was developed via theoretical analysis and experimental validation, quantitatively characterizing the influence of convective heat transfer on the strain plate surface regarding measurement accuracy. Furthermore, the implementation of an Abbe error compensation mechanism effectively mitigated nonlinear errors induced by microscale bending deformations during tensile loading. Comprehensive uncertainty analysis was conducted to evaluate both the standard uncertainty components from various influencing factors and the overall measurement uncertainty of the calibration system. Experimental results demonstrate that the proposed laser-interferometry-based digital image correlation calibration device reduces measurement uncertainty in standard strain fields to 1.9%-0.83%. This study establishes a crucial reference for developing a traceable calibration framework for digital image correlation-based strain measurement systems.
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Inter-turn short-circuit fault diagnosis of dual three-phase permanent magnet synchronous motor based on adaptive tracking method

FU Chupinga, LI Hui, XIANG Xueweia

Abstract: (149) HTML (0) PDF (0.00 ByteKB) (0)

In terms of the diagnosis of inter-turn short circuit (ITSC) faults of dual-three-phase permanent magnet synchronous motors (DTP-PMSMs), the conventional methods are easily affected by factors such as fault saliency and feature extraction frequency, and the fault index fluctuates with the change of operating conditions, making it difficult to maintain the diagnostic accuracy. Therefore, a closed-loop diagnosis method using model reference adaptive system (MRAS) observer is proposed in the essay. Firstly, the ITSC models are established according to the structure diagram of MRAS system. And the harmonic current is obtained by the space vector decomposition (VSD). Then, based on the residual signal, the fault characteristics of the fundamental component of the short-circuit current are extracted, and the adaptive law is designed through the piecewise PI controller, so as to implement closed-loop adjustment of the parameters to be evaluated in the adjustable model. Finally, a phase-shifting 30° asymmetric six-phase PMSM is chosen as the object of simulation analysis, and the results show that the proposed diagnostic strategy has better diagnostic accuracy and adaptability than the traditional open-loop diagnostic method. Compared with the traditional open-loop fault diagnosis system, the diagnosis error of the proposed strategy is reduced by 20-25% in the working range where the speed and torque fluctuate ±by 40% compared with the rated operating conditions.
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Safety Risk Evaluation Indices and Fuzzy Evaluation Model for Construction and Operation of Cavern Group

LIU Yuanpeng, JIANG Yongdong, LI Xiaojun, WANG Yazhao, WANG Xuelei, ZHANG Hongtao

Abstract: (115) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the safety of construction and operation of underground engineering, taking the complex cavern group of a “818 project” as the research background, the first-level evaluation index system of “man-materials-management-environment”, and the second level evaluation index system of 15 aspects such as technical quality of inspectors Technical support , personnel quality , seepage and leakage of cavern group, disease remediation effect, safety inspection , rainfall, etc. were constructed. Four risk levels such as Ⅰ (inadmissible), Ⅱ (undesirable), Ⅲ (allowable), Ⅳ (negligible) for construction and operation of cavern group were put forward, and a two-level fuzzy comprehensive evaluation model for the operation safety of the “818 project” cavern group was established. According to the fuzzy evaluation matrix of four indicators of man, materials, management and environment, combined with the construction and production data, the single-factor fuzzy evaluation matrix and indicator weights of the first and second levels were obtained by AHP method. and the construction and operation safety of “Project 818” cavern group were predicted. The grade evaluation value δ= 2.3445, the risk level is grade IV, that is, the risk is less likely to occur. The research conclusions provide a scientific basis for the construction and operation safety of the cavern group.
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Research on equilibrium of green certificate-power market considering users' purchase utility of green certificate

WEI Yang, LIU Chang, ZOU Rui, XU Weiting, MA Ruiguang, LI Chen, CHEN Lipin, XIANG Mingxu

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The construction of the green certificate market promotes the development of renewables. The green certificate market is closely coupled with the power market. Hence, the market equilibrium analysis and the market mechanism design need to consider the interaction between the aforementioned two markets. However, the existing research does not consider the differentiated purchasing utility of green certificates for different types of users and the market-oriented formation mechanism of the green certificate price, which leads to the deviation of the user behavior modeling in the green certificate-power coupling market. As a result, the coupling relationship between the above two markets cannot be accurately reflected. With this in mind, this paper proposes a green certificate-power market equilibrium analysis method considering the users’ purchasing utility of green certificates. A bi-level optimization model of the green certificate-power market considering the purchasing utility of green certificates is constructed. By adjusting the parameters of the purchasing utility function, the differentiated green power demand for users can be reflected. The market-oriented formation of the green certificate price can be realized through the green certificate market clearing model. Based on Karush-Kuhn-Tucker conditions, linearization technology, and diagonalization algorithm, the constructed bi-level optimization model is iteratively solved to obtain the equilibrium results of the green certificate-power market. Based on the case studies conducted on the standard test system, this paper finds that the incentive effect of the key parameters of the green certificate market on the users’ green power consumption is significantly affected by their purchasing utility of green certificates. Also, the necessity of considering the users’ purchasing utility of green certificates during the design of the market mechanism is demonstrated.
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Control Strategy of Energy Storage Virtual Synchronous Railway Power Conditioner

LIU Yuantao, TIAN Mingxing, LIU Guoqing, SU Zhaoxu, LI Xiaolin

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With the increase of the proportion of new energy power generation and the low inertia characteristics of the external power grid, the traditional traction power supply system lacks effective inertia response ability, which leads to the frequency stability challenge of the traction power supply system. In view of the above problems, this paper proposes an energy storage based virtual synchronous generator railway power conditioner (ES-VSG-RPC) control strategy. Firstly, the basic principle of ES-RPC dynamic compensation of negative sequence current and harmonic current is analyzed, and the current compensation control strategy is studied. Then, according to the load power and frequency of the left and right power supply arms, a system frequency considering load weight is proposed, and the traction power supply system is equivalent to a single-area power supply system. Then, by combining the swing equation of synchronous generator and the power equation of super capacitor, the active power of energy storage device is controlled by system frequency, and the inertia response process of synchronous generator is simulated. A DC-DC control strategy of ES-VSG is proposed. Finally, the time domain simulation model is built in MATLAB/Simulink to verify the effectiveness of ES-VSG-RPC control strategy under typical working conditions of traction power supply system. The results show that in the low inertia traction power supply system, ES-VSG-RPC can not only ensure the dynamic compensation of power quality, but also dynamically control the charging and discharging power of energy storage, improve the frequency stability of traction network and support its dynamic operation.
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Research on performance enhancement of piezoelectric vibration energy harvester based on multi-degree-of-freedom dynamic magnification method

JI Zhenfeng, WU Liangke, WU Pengfan, ZHAO Chenxi, SONG Yihui, LI Jizhen, MU Xiaojing

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A multi-degree-of-freedom dynamic magnifier (MDOF-DM) is proposed, aiming to enhance the output performance of the piezoelectric vibration energy harvester (PVEH). By combining a simplified device model and using COMSOL Multiphysics software, the frequency response curves of the PVEH with and without the MDOF-DM were obtained, the results reflected that the MDOF-DM can enhance the electrical output of the energy harvester. Based on the simulation model, the dimensional parameters of the MDOF-DM were optimized, and the influence of these parameters on the difference between the system’s first two resonant frequencies, as well as the impact of each structural parameter on the electrical output performance of the PVEH, were investigated. Experimental frequency response results showed that when the difference between the first two resonant frequencies of the system is minimized to 90.74 Hz, the peak value of the open-circuit voltages of the piezoelectric bimorph in series reached 18.78 V and 10.26 V, respectively, which are767% and 371% higher, compared to the PVEH without the MDOF-DM. The optimized load power at the two resonant frequencies reaches 933.23 μW and 344.14 μW, respectively. The experiments demonstrate that this method can significantly enhance the output performance of PVEH.
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Semi-Plane Contact Analyses Considering Localized Temperature Change

lichaoxin, jinxiaoqing, shoushaokai, liukuanyu, tanxiaofeng, dongqiuyu

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In material contact problems, localized subsurface temperature change can lead to changes in the stress gradient, which significantly affect the contact performance and service life of the material. In practical engineering materials, regions of localized temperature change often exhibit irregular shapes with smooth curved edges or sharp corners, pose substantial challenges for analytical solutions. This paper presents an algorithm based on singular integral equation of the first kind to solve the frictionless contact of a half-plane with a localized subdomain, subjected to temperature change, with a rigid circular punch. Compared to the finite element method, this work only requires discretization of the contact region, thereby significantly enhancing computational efficiency. By comparing with the classical Hertzian solution, the noted effect of localized subsurface temperature change on the contact region is verified. Taking a half plane with rectangular or circular temperature rise regions in contact with a rigid punch as examples, the computational results of current method are compared with those of the finite element method, which further demonstrate the accuracy and efficiency of the algorithm.
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Underwater Magnetic Induction Communication Based on Magnetic Rod Antenna

QIU Shutian, WANG Jianpin, JIN Jianhui, ZHANG Guo

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Traditional underwater magnetic induction communication faced issues such as directional sensitivity, short communication distances, and insufficient reliability due to the use of unidirectional coils. To address these problems, the study combined magnetic induction theory and utilized magnetic rod antennas as transmitting and receiving devices, analyzing orthogonal omnidirectional magnetic rod antennas. Simulation results showed that, under the same conditions, magnetic rod antennas outperformed unidirectional coils in communication effectiveness, and tested the impact of angular placement of orthogonal omnidirectional magnetic rod antennas on induced voltage. To validate the conclusions, an experimental platform was set up, and the results were consistent with the simulations, proving that magnetic rod antennas have strong transmission and reception capabilities, better small signal reception, and can effectively improve communication distances. The orthogonal omnidirectional magnetic rod antenna combines the excellent communication capabilities of magnetic rod antennas while mitigating directional sensitivity issues. Additionally, the non-coincident design reduces fabrication complexity. Theoretical analysis met expectations, providing new insights for underwater magnetic induction communication and demonstrating its potential for future underwater communications.
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Investigation into emergency anti-galloping method for iced quad-bundle conductor lines using anchor pulling

YANG Hao, YAN Bo, GAO Yingbo, ZHANG Bo, LV Zhongbin, Liu Guanghui, WU Xingwang, DENG Huachao

Abstract: (89) HTML (0) PDF (0.00 ByteKB) (0)

In natural ice and wind conditions, galloping of a transmission line is unpredictable. Temporary anchor pulling is a new emergency technology to suppress galloping when it takes place. The galloping process of a typical iced quad-bundle conductor line is numerically simulated, and the characteristics of vibration modes, amplitude and frequencies during galloping are analyzed. The numerical simulation method for dynamic response after employing anchor pulling during galloping is studied. For the galloping with vibration modes of single loop, double loop and triple loop that most frequently takes place, the effects of pulling positions and loads on galloping suppression efficiency and tension variation in conductor are investigated by means of the obtained method, and the pulling loads in the cases of the same vibration mode with different vibration amplitudes are discussed. The principles for determining pulling positions and loads during the implementation of temporary anchor pulling for emergency galloping suppression are provided, offering important guidance for the application of this emergency galloping suppression technology.
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Study on admittance modeling simplification ofbrushless doubly-fed grid-connected power generation system

Tu Jin Wei, Su Jing Yuan, Hu Hong Sheng, Feng Hao

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The brushless doubly-fed induction generator (BDFIG) realizes the induction excitation because of the special structure design such as double stators, and eliminates the brushes and slip rings, and thus has obvious advantages in the grid-connected power generation application in harsh environment. However, the special designed double-stator structure also leads to higher-order and multi-parameter machine model, and further leads to the complicated mathematical model of the grid-connected system. The complexity of the grid-connected system model often check the symbolic operation upper limit of MATLAB, MathCAD and other softwares. Therefore, most of the existing brushless doubly-fed grid-connected studies simplify the mathematical model by ignoring some or all of the resistance parameters, but the impact of the simplified method on the accuracy of the modeling is not assessed, and the applicable conditions are not clear. In view of this, aiming at the port admittance model reflecting grid-connected stability, this paper fully considers the difficulty of grid-connected modeling caused by the high-order and multi-parameter characteristics of BDFIG, and systematically carries out the simplification and accuracy verification from open-loop modeling to closed-loop modeling. Finally, the simplified admittance model ensuring accuracy is obtained. Based on it, the control parameters are designed and applied to the simulation system and experimental platform. The waveforms under different load and grid strength conditions prove the accuracy of the proposed simplified admittance model and the effectiveness of the designed parameters.
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A multi-factor graph optimization localization algorithm for mobile robots based on multi-scale point cloud registration

tan wen zhou, ou yang qi, liu jin jiang

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A multi-factor graph optimization-based mobile robot localization algorithm is proposed, utilizing multi-scale point cloud registration, in order to address the issue of unstable performance of point cloud registration affecting the localization accuracy of mobile robots in real-world environments. First, a multi-scale registration model is established, where point and surface element features are associated through attribute filtering in the octree-based feature map, and the pose is iteratively optimized to improve the stability of point cloud registration. Secondly, a sliding window optimization model based on factor graphs is constructed, incorporating multiple constraint factors from LiDAR, IMU, and wheel encoders to optimize the pose and enhance localization accuracy. Experimental results in multiple scenarios show that, in indoor environments, the proposed algorithm reduces the average localization error by 57.79% and 33.71% compared to the LIO-mapping and LIO-SAM algorithms, respectively; in outdoor environments, the average localization error is reduced by 74.00% and 59.37%, respectively, compared to the LIO-mapping and LIO-SAM algorithms. The proposed algorithm significantly improves the localization accuracy and stability of mobile robots.
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Dynamic obstacle avoidance method integrating Kalman Filter and improved DWA in unknown complex environments

LI Yan, Feng Yong-Yi, LI Ming-hui

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Aiming at the challenge of mobile robots struggling to effectively avoid dynamic obstacles in unknown and complex environments, an obstacle avoidance method that integrates Kalman filtering and an improved Dynamic Window Approach (DWA). First, the Kalman filter algorithm is utilized to predict the motion trends of dynamic obstacles based on real-time position data. The predicted points are then expanded in conjunction with the actual positions of the obstacles, preventing collisions caused by intersections between the robot’s trajectory and the predicted obstacle path. Next, to address the local optimal problem that may arise when the robot and dynamic obstacles move synchronously during avoidance, a new evaluation function based on the angular direction is introduced. This function improves the scoring of the opposite side of the target trajectory, providing more options for avoidance directions. Additionally, to overcome the issue of trajectory oscillation near the target point due to unreasonable weight distribution, an adaptive method is proposed to automatically adjust the weight of the angular direction function based on the angle difference between the robot and dynamic obstacles, thereby adapting to environmental dynamic changes. Finally, the fusion of Kalman filtering with the improved DWA enables the mobile robot to plan its motion trajectory in advance based on the predicted motion trends of obstacles, enhancing the safety of obstacle avoidance. Simulation and experimental results demonstrate that the proposed algorithm can effectively avoid various dynamic obstacles in unknown and complex environments and prevent the robot from becoming trapped in dynamic local minima.
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Analysis of Temperature Characteristics of 5kW Air Cooled Fuel Cell

ZHANG Jing, HE Haibo, LU Weiye, FAN Chengzhi, XU Cong, WANG Hui, He Yixuan, WAN Zhongmin

Abstract: (132) HTML (0) PDF (0.00 ByteKB) (0)

[ ]:With the world"s increasing attention to environmental pollution and energy scarcity, improving the output performance of proton exchange membrane fuel cells (PEMFCs) has become one of the key directions in new energy research. Temperature is an important parameter that affects the output performance of fuel cell systems. If the battery temperature is too high, it can cause dehydration of the membrane electrode and reduce the proton conductivity of the membrane; Low battery temperature can reduce catalyst activity and affect the electrochemical reaction of the fuel cell stack. This experiment analyzed and studied the temperature variation of anode closed air cooled fuel cells with load current. The experimental results show that regardless of whether the load current increases or decreases, the rate of change and temperature uniformity of the fuel cell stack temperature are related to the step size of the load current change. At the same time, the speed of the fan and the water content inside the fuel cell stack also affect the temperature distribution of the fuel cell stack.
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Preparation of low dielectric loss palm oil-based trimethylolpropane ester insulating oil

Hujiangtao, Lijian, Luoyao, Wangchaofan, Huangzhengyong

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Natural ester insulating oil has the advantages of high fire point, renewability and good biodegradability. Compared with mineral insulating oil, natural ester insulating oil has the problem of high dielectric loss factor, which affects the use of natural ester insulating oil in transformers. In order to reduce the dielectric loss factor of natural ester insulating oil and take into account the basic properties, transesterification-modified palm oil-based trimethylolpropane ester insulating oil was prepared, and the influences of molecular structures on the polarization characteristics of natural ester insulating oil were studied by quantum chemical calculation. The results show that the polarization characteristics of natural ester insulating oil are closely related to its molecular structure and functional groups, and the dielectric loss of plant insulating oil can be reduced by increasing the carbon number of lipid chains and reducing the content of C=C double bonds. Based on quantum chemical calculations, palm oil was selected as the basic unit, and the prepared palm oil-based modified polyol esters had a low dielectric loss factor of only 0.4%.
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The Classifications and Characterizations of Safety Hazard Texts

QIAO Jianfeng, LIU Xuan, AI Lisha, ZHANG Liwei, WANG Ting

Abstract: (95) HTML (0) PDF (0.00 ByteKB) (0)

To improve the efficiency of organizing and retrieving hazard information data and support more complex information processing tasks, effective technical methods need to be adopted for automatic data classification and type analysis. Support Vector Machine (SVM) can automatically classify free text. However, the working principle of the algorithm is to find the optimal classification boundary in the training set, and cannot discover typical type features. So, a normalized entropy model is proposed to search for typical type features, which improves the current TFIDF (Term Frequency Inverse Document Frequency) type feature recognition method. Taking 2534 law enforcement inspection records from a government emergency management bureau as an example, SVM was used for automatic classification, with an accuracy rate of up to 97%. At the same time, the normalized entropy model was used to provide typical characteristics of each type, providing decision support for formulating special rectification strategies for hazard investigation. The experimental results show that the combination of SVM and normalized entropy model can efficiently solve the comprehensive problem of text classification and type feature recognition.
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Application Analysis of Voltage Unbalance Suppression in Distribution Networks Using Star-delta Transformers

REN Jiangbo, DENG Xiaoyong, ZHENG Zongwei, SHANG Guanguowei, LIU Hanying, TIAN Feng, DU Lin, WU Peihong

Abstract: (199) HTML (0) PDF (0.00 ByteKB) (0)

The stochastic nature of single-phase loads exacerbates the three-phase voltage imbalance in low-voltage distribution networks, and the existing three-phase load imbalance control measures for low-voltage distribution networks mainly use two types of phase-change load casting and additional imbalance compensation devices, discontinuity of power supply, long compensation process, and complexity of the system, have made the management of the three-phase voltage imbalance a difficult problem that needs to be solved urgently. This paper proposes and analyses the method of adaptive regulation of Y-△ connection topology power transfer transformer to suppress three-phase unbalance in low-voltage distribution network, simulates and analyses the principle and influencing factors of three-phase unbalance suppression by power transfer transformer, builds a simulation experimental platform based on Y-△ power transfer transformer to suppress three-phase voltage unbalance, and analyses voltage unbalance suppression law under different unbalanced loads. The application of Y-△ coupling transformer in actual transmission lines is also analysed. The experimental and field data show that based on this method, without active control, it can balance three-phase power automatically and in real time, and improve three-phase load imbalance.
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Optimization Design of Planar Transformers under Multi Output High Coupling

LIU Zelong, LUO Ciyong, XING Zihao, WANG Ziwen

Abstract: (126) HTML (0) PDF (0.00 ByteKB) (0)

Parasitic parameters, such as leakage inductance and parasitic capacitance, are often used as indicators for optimizing planar transformers. However, simply changing the interlayer winding arrangement only reduces leakage inductance while inversely increasing parasitic capacitance, complicating the optimal transformer design. This paper investigates an interlaced winding structure within layers under a high coupling strategy, achieving simultaneous reductions in leakage inductance and parasitic capacitance. This paper also improves the leakage inductance calculation for interlaced structures within layers, addressing the issue of applying the MMF algorithm. Furthermore, this paper analyzes the energy loss distribution and other parameters of the interleaved structure through model simulation of a four-layer plate transformer, comparing the differences in parasitic parameters across various winding structures. The results demonstrate that the proposed winding structure exhibits lower parasitic parameters and reduced AC resistance. Finally, a planar transformer is fabricated to verify the performance of the proposed structure.
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Equivalent Circuit Modeling and Electrical Stress Analysisof Press-pack IGBT Modules Considering Distributed Parameter Variations

chenxinrui, lihui, yaoran, laiwei, yuanwenqian, jiyirun, yangminxiang, huaiqing, yuanqian

Abstract: (149) HTML (0) PDF (0.00 ByteKB) (0)

As the core component of the flexible DC converter valve, the performance of the high-voltage and high-power press-pack IGBT module directly affects the safe and reliable operation of the converter system. However, the flexible DC converter valve sub-module adopts multi-module stacking series and multi-chip parallel connection to improve the voltage and current level, and its structural characteristics lead to the difference of distribution parameters in the module, and it is of great significance to study the non-uniform electrical stress distribution of IGBT module under the influence of distribution parameter differences. In this paper, the differences in the distribution parameters caused by the asymmetry of the IGBT multi-module stacking sub-modules are analyzed, and the distribution parameters of the press-pack IGBT modules are extracted. Secondly, the multi-chip parallel equivalent circuit model of IGBT module is established, and the uneven electrical stress distribution under the influence of parasitic inductance and parasitic resistance distribution parameters is analyzed, and the accuracy of the equivalent circuit model is verified by datasheet comparison. Finally, the electromagnetic field finite element model of the IGBT module is established, and the simulation results further verify the effectiveness of the equivalent circuit model.
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Multi regional power consumption prediction in large-scale construction projects based on xLSTM

Wang Bing, Yang Qingshan, Jiang Yougao, Xu Xiantao, Wang Kai

Abstract: (194) HTML (0) PDF (0.00 ByteKB) (0)

With the continuous expansion of water resource allocation projects, accurate prediction of electricity consumption is crucial for energy conservation, cost control, and construction efficiency. Traditional power consumption prediction methods, such as LSTM and Transformer, are difficult to capture both short-term and long-term dependencies when processing complex time-series data. To address this challenge, this paper proposes using xLSTM (Extended Long Short Term Memory Network) to predict power consumption in multiple regions. XLSTM combines the short-term dependency modeling advantages of sLSTM with the long-term dependency modeling capabilities of mLSTM, and can effectively process power consumption data between multiple regions, considering the temporal correlation between different regions. The experimental results show that xLSTM performs well in multi regional power consumption prediction, with a mean square error (MSE) of 0.0030 and an average absolute error (MAE) of 0.035, which is superior to other models. This model provides effective technical support for precise prediction of electricity consumption, and can provide strong guarantees for accurate decision-making and intelligent scheduling management in large-scale water resource allocation projects.
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Improved Model for Non-Isothermal Crystallization Kinetics of Thermoplastic CF/PEEK Composites

NIE Jiahong, SONG Zengrui, NING Huiming

Abstract: (238) HTML (0) PDF (0.00 ByteKB) (0)

As a high-performance semi-crystalline thermoplastic composite material, the mechanical properties of carbon fiber reinforced polyether ether ketone (CF/PEEK) are closely related to its thermoforming process parameters. The material undergoes complex thermodynamic processes during the thermoforming process, so it is crucial to study its crystallization process with an accurate and practical crystallization kinetic model. Existing theoretical models for non-isothermal crystallization of thermoplastic composites are often difficult to obtain the parameters and have the problem that the final relative crystallinity cannot reach 1. For this reason, this paper proposes an improved nonisothermal crystallization kinetic model for thermoplastic composites based on the Mampel model using a new segmented functional form to simplify the expression of the crystallization rate function K(T), and analytically validates the model on CF/PEEK thermoplastic composites. The results show that the model can not only solve the problems of difficult to obtain the parameters of the existing models and the final relative crystallinity cannot reach 1, but also significantly improve the prediction accuracy of the relative crystallinity and crystallization rate of the non-isothermal crystallization process of CF/PEEK, thus verifying the reliability of the model.
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Study on the Impact of Dissolved Oxygen on Aerobic Granular Sludge Systems with Different Influent Organic Matter

CHEN Zeyu, YANG Rui, JIANG Liwen, TONG Meiling, FANG Fang, GUO Jinsong

Abstract: (251) HTML (0) PDF (0.00 ByteKB) (0)

In order to elucidate the mechanism of the influence of dissolved oxygen (DO) on the aerobic granular sludge (AGS) system, the differences in pollutant removal, microbial community structure and functional genes of AGS systems with different influent organic matter concentrations were studied under the conditions of 4-6 mg/L and 2-4 mg/L, respectively. The results showed that after the DO concentration was reduced, the COD and TP removal rates of low-organic reactor R1 and high-organic reactor R2 remained high, while the endogenous denitrification rates of synchronous nitrification increased by 17.54% and 7.05%, respectively, and the contribution rate of endogenous denitrification to nitrogen removal increased by 9.84% and 6.11%. The decrease of DO drove the adjustment of microbial community structure, promoted the increase of the abundance of functional bacteria for nitrogen and phosphorus removal in AGS, and improved the abundance of denitrification and genes related to internalized carbon sources, which was conducive to achieving good phosphorus and nitrogen removal performance in AGS system. The study also found that DO changes have a more significant impact on low-organic AGS systems, and more accurate DO regulation should be implemented in actual operation. This study provides a theoretical basis for long-term stable nitrogen and phosphorus removal in AGS system.
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Non-stationary load forecasting based on optimized VMD and Informer-BiLSTM

Yanxiuying, Zhaoshanxi, Liyang, Tahao

Abstract: (198) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the problems of strong periodicity, high volatility and low prediction accuracy of regional power load data, a non-stationary load forecasting method combining optimized variational mode decomposition(VMD) and Informer-Bidirectional Long Short-Term Memory (Informer-BiLSTM) is proposed. By introducing the crested porcupine optimizer (CPO), the number of modes and weight coefficients of VMD are optimized, and the complex load time series is effectively decomposed into multiple intrinsic mode functions to extract key time-frequency features. Subsequently, a parallel prediction model was constructed using Informer and BiLSTM to accurately predict each component after decomposition, and an integrated algorithm was introduced to further reduce the prediction error. The experimental results show that the prediction accuracy is significantly improved compared with other combined prediction models.
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Tensor Completion of Missing Electricity Data in Transformer District Based on CP Decomposition and Nuclear Norm Regularization

LI Xinhong, YANG Chao, LIU Qingchan, FU Zhihong

Abstract: (100) HTML (0) PDF (0.00 ByteKB) (0)

In response to the issue of data quality loss in the actual collection, transmission, and storage of massive electricity data, this paper proposes a method for reconstructing electricity data based on CP decomposition and kernel norm regularization joint constraints, utilizing the temporal and spatial correlations of large-scale substation user electricity data. Firstly, a tensor of electricity consumption data for the substation area is constructed based on some potential similar characteristics of the electricity consumption behavior of large-scale substation users; Secondly, the F-norm and kernel norm are selected to regularize Gaussian noise and ideal complete electricity data, respectively, to establish tensor recovery models; Finally, the matrix factors obtained from CP decomposition are alternately updated column by column until convergence, thereby achieving high-precision completion of missing data. The effectiveness and accuracy of the algorithm were verified through simulation analysis and comparative experiments.
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Progress in the application of electromagnetic pulse de-icing technology and current research status

Tang Fangchuna, He Jiaa, Feng Junxina, Mei Hongdengb, Liu Chaoyangc, Jiang Xingliangd, Hu Qind

Abstract: (312) HTML (0) PDF (0.00 ByteKB) (0)

Electromagnetic pulse (EMP) de-icing technology refers to the form of pulsed current or pulsed magnetic field, which converts EMP energy into pulsed force, changes the shape of metal materials, destroys the adhesion between the ice layer and the surface of the material, and never achieves the purpose of ice layer falling off. This paper, from the research background of electromagnetic pulse technology, the influence of de-icing incentive factors, and the use of different industries in three aspects, combing the role of electromagnetic pulse de-icing technology principle, reviewed the progress of the relevant basic theory research at home and abroad; from the structure of the response, the size of the pulse current, the thickness of the metal material, the coil-metal material spacing in four aspects, analyzed the factors affecting the effect of de-icing; respectively, from the application and basic theory The problems of EMP de-icing technology are pointed out from two aspects, and the research direction of EMP de-icing technology is expected from three aspects, namely, intelligent control system, optimization of metal materials and numerical calculation.
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The medical image segmentation algorithm based on multi-scale and multi-axis feature fusion

YANG Fei, YANG Guangchao

Abstract: (220) HTML (0) PDF (0.00 ByteKB) (0)

Automatic medical image segmentation based on deep learning plays a crucial role in clinical diagnosis and treatment. To address the limitations of traditional convolutional neural network (CNN) models, which are constrained by local receptive fields, and the overfitting issues of Transformer and multilayer perceptron (MLP) models on small medical image datasets, we propose a multi-scale multi-axis feature fusion model called MSAFNet. This model employs a novel multi-axis mixed residual channel attention block (MX-RCAB) that focuses on local details and global dependencies, thereby enhancing feature representation in both spatial and channel dimensions. Additionally, it utilizes a spatial cross-gating block (SCGB) to filter redundant information and capture discriminative low-level details, thereby improving segmentation performance. Experimental results on the Synapse and ACDC datasets demonstrate that MSAFNet achieves average DSCs of 85.59% and 92.37%, respectively, outperforming representative medical image segmentation methods such as nnUNet and TransUNet.
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UAVDet: Lightweight Detection Algorithm for Aerial Imagery of Dense Traffic Targets

lIN Zhiqiang, ZHONG Mingen, FAN Kang, TAN Jiawei, ZHANG Yihong

Abstract: (220) HTML (0) PDF (0.00 ByteKB) (0)

To address the issues of low detection accuracy for small-scale objects and large model parameters in aerial images of dense traffic, we propose a lightweight and efficient aerial image detection algorithm model, UAVDet. First, we design the large-kernel separable attention spatial pooling module (LSKASPM) to enhance the model's ability to capture spatial and semantic information for small-scale objects. Next, we construct the deformable context feature-guided aggregation module (C2f-DCG) to improve the model's feature understanding across multiple scales. Then, we introduce the multi-scale feature fusion module (MSFM) to aggregate high-resolution detection branch (SHead) features and provide more fine-grained global features. Finally, the layer-wise adaptive sparse pruning technique (LAMP) based on network weight magnitudes is applied to reduce the model's parameter size. Experimental results on the public VisDrone dataset show that the model achieves an average detection accuracy of 47.2% and a missed detection rate of 47.5% for ten common traffic target classes in urban areas. The model has 6.3M parameters and an inference speed of 197 frames per second, outperforming existing public algorithms. The relevant algorithm code will be publicly available at https://github.com/XMUT-Vsion-Lab/UAVDet.
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Design of railway wind-break wall in gale areas based on three-dimensionalflow field

ZHANG Youpeng, HAO Zhihua, ZHAO Shanpeng, Li Xiaoping, GE Leijiao, MIN Yongzhi, WANG Jiaan

Abstract: (121) HTML (0) PDF (0.00 ByteKB) (0)

The Lanzhou-Xinjiang High-Speed Railway passes through regions frequently affected by strong winds. Although the construction of wind-break walls can effectively ensure train safety, it exacerbates the galloping of the catenary positive feeder. To suppress the galloping of the positive feeder, this paper establishes a three-dimensional flow field model of wind-break walls with different wall top structures and perforation types based on fluid dynamics theory, and optimizes the design of the wind-break wall structure. The results show that different wall top structures of the wind-break wall alter the flow field around and behind the positive feeder line, reducing wind speed at the wire and decreasing the extent of the high-speed wind zone. When the gap ratio of the city wall-type wind-break wall is 0.5, the lift coefficient and drag coefficient of the positive feeder line decrease by 26.40% and 12.13%, respectively. The larger the porosity of the wind-break wall, the smaller the extent of the high-speed wind zone behind the wall, and the lower the wind speed. The reduction in wind speed at the positive feeder line is significant, and the airflow tends to stabilize. Under the circular perforated wind-break wall with a porosity of 0.4, the lift and drag coefficients of the positive feeder line decrease by 51.15% and 45.59%, respectively. By reasonably designing the wind-break wall structure, the galloping of the positive feeder can be effectively suppressed.
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Simulation study on the design of zero-frequency nonlinear ultrasonic phased array probe

WANG Hang, LIU Yaolu, CHEN Guang, HU Ning

Abstract: (201) HTML (0) PDF (0.00 ByteKB) (0)

The static component of the ultrasonic signal, also known as the zero-frequency signal, can be used as a nonlinear ultrasonic feature coefficient for the detection and imaging of early damage and microcracks in materials due to its advantages of small attenuation and easier accumulation in the guided wave. Based on this, a zero-frequency nonlinear ultrasound phased array probe with high and low frequency wafers vertically stacked on top and bottom is designed, which can receive zero-frequency signal more efficiently and thus improve the detection capability of nonlinear ultrasound detection technology. Firstly, a two-channel zero-frequency nonlinear ultrasound probe with the wafer vertically stacked on top and bottom is designed, and it is verified that it is more sensitive to zero-frequency signal than the traditional single-center-frequency probe. Secondly, four zero-frequency nonlinear ultrasound phased array probes with different numbers of low-frequency wafers but the same number of high-frequency wafers are designed by vertical stacking of top and bottom, and it is found that the number of low-frequency wafers can be appropriately reduced when designing zero-frequency nonlinear ultrasound phased array probes and the low-frequency wafer width is preferably no more than 1/4 of the lateral resolution of zero-frequency signal by comparing the received signals and the imaging effect. Finally, by comparing with the conventional single-frequency phased array probe, it is verified that the zero-frequency nonlinear ultrasound phased array probe can extract the zero-frequency signal more effectively.
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A multi-channel EEG signal artifact removal method based on discrete wavelet transform and independent component analysis

liu shaocai, zhao mingfu, huang li, pan anyuan, he zhong, 王鲁瑞, wang shaofei, tang bin, wang yuhan

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Multi-channel EEG signals often contain time-frequency overlapping artifacts, and the active components of the EEG signal are easily lost when the artifacts are removed by traditional methods, especially when the frequency characteristics of the artifacts are similar to the EEG signals. In order to solve this problem, an improved artifact removal method based on discrete wavelet transform and independent component analysis was proposed. In this method, the time-frequency decomposition of the EEG signal is first carried out by discrete wavelet transform, the time-frequency characteristics of the signal are captured, and the key signal components are screened out by combining multi-dimensional feature selection and optimization techniques, and finally the FastICA algorithm is used to remove the ocular electrophrasal artifact. In particular, this method optimizes the problem of time-frequency overlap artifacts, and avoids the signal loss caused by traditional methods when the frequency of artifacts and EEG signals are similar by dynamically adjusting the feature selection and filtering strategies. Compared with the traditional method, the signal-to-noise ratio is increased by 4.5 dB, and the power ratio of alpha wave and beta wave is significantly enhanced, which proves that the quality of EEG signal can be effectively preserved while removing artifact, which provides a more efficient and reliable signal processing scheme for EEG devices.
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Trans-CNN prediction model of high and steep slope deformation based on beidou detection data

yitingjingwen, huangcaisheng, tanyong, Zhijiang Son, hexiaohan, guijingqi, wangkai

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There are often high and steep slopes during the construction process of large projections, whose deformation often leads to geological disasters. This brings harm to the safety of people"s life and property. Hence, collecting displacement data efficiently and establishing a suitable and accurate hybrid prediction model becomes essential. This study aims to propose the Trans-CNN hybrid model by fusing the CNN convolutional layer and residual residual structure in the Transformer model. This optimized Transformer algorithm model was employed for the displacement data collected by the Beidou satellite system in a large water conservancy project in Chongqing. The results found that the mae, mse and rmse values of the Trans-CNN model are lower than single models, which proves the prediction accuracy of the Trans-CNN. Thus, it can provide a feasible scheme for the prediction and analysis of the deformation of the high and steep slope in the implementation of other projects.
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Multi-feature fusion expressway travel time prediction based on toll data

zhang xin hao, han feng chun, wang jing sheng

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To enhance the expressway informational management, a model for the expressway travel time prediction problem based on exit toll data was proposed. The model combines support vector regression (SVR) and bayesian optimization algorithm (BOA), and incorporates mean filtering (MF) to denoise the dataset, while fully considering the influence of historical travel time, vehicle type, and other characteristic variables on travel time. Selected G22 Qing-Lan Expressway exit toll data for prediction experiments, the results show that the prediction model based on MF-BOA-SVR demonstrates better performance in terms of expressway travel time prediction compared to benchmark models such as back propagation algorithm (BP) and random forest (RF), and exhibits strong generalizability, on the dataset of the section from Yuchong toll station to Lanzhou East toll station, the mean absolute error is reduced by 54.80%, root mean square error by 56.11% and mean absolute percentage error by 53.94% on average.
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Investigation on failure mechanism and reliability improvement of fan-out panel level packaging under temperature cycling

Huo Yan, Liu Renkuan, Luo Xiaorong, Xie Lei, Wei Jie, Deng Gaoqiang, Wei Yuxi, Deng Xiaochuan, Li Hui

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Fan-out panel level packaging (FOPLP) has the advantages of high output rate, large exposure area, and low material loss, and is regarded as a representative of advanced packaging technology. However, due to the high-density integration of various materials and complex internal interconnection structures, the reliability of the FOPLP has been widely observed. In this paper, the reliability of FOPLP was investigated by combining multi-physics field simulation with temperature cycling tests, and a packaging optimization design was proposed. Firstly, a multi-level and multi-physics field coupling finite element simulation model was built based on the packaging structure. Secondly, the impact of component CTE was analyzed, and material matching schemes were investigated. Thirdly, the temperature cycling tests were performed, and the packaging failure mechanism was analyzed. Finally, the impact of packaging design parameters was investigated. A packaging optimization design was proposed and its reliability was validated through temperature cycling tests. The results indicated that the interface between the epoxy molding compound (EMC) on the chip surface and the heat sink was the weak point, where cracks were prone to occur and extended to the chip, ultimately leading to catastrophic failure. The stress in the low reliability components was effectively reduced by adding a 1.5 layer interconnect structure to increase the thickness of the EMC on the chip surface, thereby improving the reliability of FOPLP.
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Study on creep characteristics and creep model of initially damaged sandstone

YAO Mengyuan, DONG Chun-liang, HAO Jian-ping, XIE Ya, ZHANG Bowen

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To accurately describe the disturbance of underground rock caused by constant-rate loading and simulate the creep physical properties of rock before and after damage, unloading tests to induce damage at 60% of the yield strength under various confining pressures and creep tests with graded loading were conducted. Based on thermodynamic theory, the initial damage variable values under different confining pressures were calculated, revealing the trend of damage variables with varying confining pressures and the changes in strain differences between damaged and undamaged rocks during various creep stages. Combining the theory of component models and damage mechanics, the isochronous creep time (tc) and yield strength (σs) were used to segment the creep stages in modified Maxwell and Kelvin-Voigt bodies. By connecting the Poynting-Thomson body, the modified Maxwell body, and the modified Kelvin-Voigt body in series, a new viscoelastic-plastic creep model was developed.The results indicate that as the confining pressure increases, both the total input energy and unloading energy exhibit an increasing trend. However, for rocks damaged at 60% of peak stress, the damage variable decreases with increasing confining pressure. The study elucidates the tendency for the influence of unloading damage on rock creep stages to increase over time under uniaxial stress conditions and the pattern of this influence first increasing and then decreasing under triaxial stress conditions. The theoretical curves of the new model align with uniaxial and triaxial experimental data with a fit degree of over 0.93, confirming that the constructed viscoelastic-plastic model is applicable to rock creep tests under all stress states and damage levels, and can effectively reflect the mechanical characteristics of the three creep stages. The research findings provide a theoretical foundation for underground rock engineering and offer a new method for constructing creep models.
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Research progress on the effects of turbulence on algae in water

maoyufeng, zhangqin, lihong, yangshengfa, xiaoyi, heqiang, yuweiwei, heruixu, guowenshu, yekailai, mouxinyang, hujiang

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Hydrodynamic conditions play an essential role in the growth and migration of algae, but the response of algae to turbulence remain poorly understood. This paper systematically describes the effects of turbulence on the biomass and vertical migration of algae, as well as the key factors affecting the algae turbulence sensitivity. First, turbulence can affect accumulation of algal biomass by interfering with processes such as cell division and energy metabolism (photosynthesis and nutrient absorption). Second, turbulence can affect the vertical migra-tion behavior of algae by mediating the buoyancy and mechanical stability of algae. Finally, factors affecting the algae turbulence sensitivity are analysed from the point of view of the physiological structure of the algal cell and the phases of the cell cycle. In view of the existing problems in the current study, future research prospects are proposed in terms of deepening the molecular mechanism research of algal response, strength-ening the construction of the turbulence research system, and coupling the physiological processes of algae and the physical structure of turbulence to improve the simulation accuracy, aiming at providing scientific basis and theoretical support for the study of algal behavior under changing hydrodynamic conditions, the formulation of algal bloom prevention and control countermeasures, and the evaluation of water ecosystem service functions.
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Autonomous Response Method of Demand-Service-Function in Waterway Transportation System

chen hualong, WEN Yuanqiao, HUANG Yaming, XIAO Changshi

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Autonomy in the domain of waterway transportation represents a novel direction of development, aiming to achieve autonomous responsiveness and computation of tasks within waterway transportation systems. This constitutes the foundational issue for realizing autonomous operations within such systems. Consequently, this paper proposes an approach to demand-service-function autonomous responsiveness tailored for waterway transportation systems. Initially, a semantic model of demand, service, and functional elements within waterway transportation systems is constructed leveraging ontology tools. Subsequently, a demand-service-function autonomous responsiveness model is proposed, integrating intent, contextual logic, and Quality of Service (QoS) assurance. This model facilitates a primary mapping from transportation demands to system services through intent matching, followed by a secondary mapping from system services to object functionalities via contextual semantic logic and QoS assurance semantic matching. Finally, employing autonomous berthing of intelligent vessels as a case study, this paper elucidates the autonomous responsiveness approach. The simulation results show that the proposed method can complete the autonomous response of demand-service-function of the waterway transportation system. Compared with the service template matching method and heuristic automatic matching method, the demand response time and function mapping accuracy are improved, which verifies the effectiveness and accuracy of the autonomous response method. At the same time, it can realize the autonomous response of large-scale services, thus improving the autonomy of the waterway transportation system.
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Spectrogram texture pattern guided vocal separation

guanxin, lijinshuo, zhangruifeng, liqiang

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The spectral patterns of vocal and accompaniment have their own unique textures, but the spectral lines of vocal and accompaniment often overlap and intertwine on the spectrogram, making it very difficult to separate vocal and accompaniment from mono audio. Therefore, a stacked hourglass network that integrates multi-resolution attention and multi-channel cross-attention is proposed to finely characterize the texture features of the spectral lines of vocals and accompaniment. First, in response to the differences in spectral line density between vocal and accompaniment in the frequency dimension of the spectrogram, multi-resolution attention is applied to the features of different resolutions in the decoder, so as to utilize the appropriate resolution to represent the time-frequency texture patterns of vocal and accompaniment. Secondly, multi-channel cross-attention is proposed to better represent the instantaneous time-frequency characteristics in the frequency dimension and the flat sustained characteristics in the time dimension of the accompaniment, effectively extracting the spectrogram features of the accompaniment. Experimental results on the MIR-1K dataset show that compared with the current state-of-the-art model SHN, the number of parameters is reduced by about 33%, the vocal signal-to-noise ratio (GNSDR) index is improved by 1.35 dB, and the accompaniment is improved by 0.89 dB. The experimental results prove that a full representation of the spectrogram features of different sound sources can further improve the separation effect of vocal and accompaniment.
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The Study of Corrosion Performance of Q235 Steel under Surface Deformation Strengthening

ZHAO Jing, LI Shengfang, GAN Wenyan, SHE Qianhao, MENG Xian, ZHANG Fuhao, YANG Xiaofang, YUAN Yuan

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In this study, preliminary findings from solution immersion and soil simulation corrosion tests reveal a significant improvement in the corrosion resistance of Q235 steel after surface deformation strengthening treatment. Based on these results, further investigations were conducted on its electrochemical performance in soil-simulating solutions with varying pH levels, chloride ions (), and sulfate ions () concentrations. The corrosion behavior was analyzed using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results indicate that surface deformation strengthened Q235 steel (ST-Q235) exhibits superior corrosion resistance compared to Q235 steel in chloride environments of different concentrations, showing sensitivity to high levels. In sulfate environments, the corrosion rate of Q235 increases with higherconcentrations, while ST-Q235 forms a passivation layer in highconcentrations, demonstrating good corrosion resistance. Additionally, at a higher pH value (pH 6), the corrosion rate of ST-Q235 significantly decreases, showing markedly better corrosion resistance compared to Q235.
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Mandarin lip recognition based on MSAF with multimodal task

RONG Yujun a, WU Xianhai b, CAI Fenglin b, Yang Tongxin b, LI Penghuac

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Multimodal lip recognition aims to enhance speech recognition accuracy and robustness by integrating lip movements and speech information, while also aiding specific user groups in communication. However, existing lip-speaking models predominantly focus on English datasets, leaving research on Chinese lip recognition in its nascent stage. Addressing challenges in handling data features across different modalities, integrating these features, and achieving comprehensive fusion of multimodal features, we propose the Multimodal Split Attention Fusion Audio Visual Recognition (MSAFVR) model. Through experiments utilizing the Chinese Mandarin Lip Reading (CMLR) dataset, our model, MSAFVR, demonstrates significant advancements, achieving a remarkable 92.95% accuracy in Chinese lip reading, surpassing state-of-the-art Mandarin lip reading models.
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Quasi-Static Analysis for Wind Disasters Fragility of Ultra-High Voltage Long-Span Transmission Tower Lines

Shi Zhiyu, Zhang Shulin, Meng Xianqiao, Zheng Zhixiang, Li Zhengliang

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The Ultra-high voltage (UHV) and long-span (LS) transmission lines, which have large tower heights and long span distances, are susceptible to wind loads. Wind fragility analysis of these structures is an important method for assessing their reliability against wind. This study, taking an UHV-LS transmission tower in Anhui province as the background, based on random wind vibration response analysis engineering theory and China"s current overhead transmission line loading specification to obtain the structural effect distribution of the LS transmission tower under the action of the wind load, took into account the uncertainty of the structural material parameters to establish the probability distribution of wind load carrying capacity. Additionally, this study used the top of the tower displacement, the corrected angle of the inter-segmental displacement as an indicator of determining the level of performance quantitative modeling, and based on these calculations to obtain the transmission tower wind fragility curve. The results indicated that: the wind effect distribution of the quasi-static transmission tower line system could be obtained by the first time beyond the probability theory; the multiple performance level of the UHV-LS transmission tower line system based on the tower top displacement is more conservative than that based on the modified inter-nodal displacement angle; with the aggravation of the structure damage, the influence of structural uncertainty on the bearing capacity of the structure becomes more obvious; the wind fragility analysis shows that the UHV tower has good wind reliability under the design wind load, but its wind damage shows some brittleness.
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The pathway of transition toward turbulence for thermocapillary convection in liquid bridge with small Prandtl number

JinYisong, ZengZhong, ChenShuo, LiHao

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Thermocapillary convection driven by surface tension gradient undergoes a series of bifurcation and ultimately evolves into a chaotic state, while temperature difference between the upper and lower ends of the liquid bridge increases. This study employed three-dimensional numerical simulations to investigate the convection transition for Prandtl numbers(Pr) of 0.01 and 0.02 with aspect ratio (a ratio between height to radius) of 1 under microgravity. This study utilized time series spectrum analysis and dynamic mode decomposition to elucidate the spatiotemporal structure of the flow field. The results show that thermocapillary convection in liquid bridges with Pr=0.01 and Pr=0.02 transitions to turbulence through quasi-periodic bifurcation pathways. Specifically, the Pr=0.01 case exhibits a two-frequency quasi-periodic oscillation with frequency-locking characteristics, while the Pr=0.02 case demonstrates a three-frequency quasi-periodic oscillation. During the periodic oscillation stage, thermocapillary convection in liquid bridges with Pr=0.02 shifts from pulse oscillation to rotational oscillation, with wave number changing from a mixture of 1 and 2 to a dominant 2. In contrast, the Pr=0.01 case remains pulsed in both periodic and quasi-periodic phases, with a wave number that remains a mixture of 1 and 2.
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Optimization of Data CenterIntegrated Energy System Configuration and Scheduling Operation

Liu Xu, Fan Wei, Ji Hongtao, Zhen Ce, Gao Mingxing, Wang Lichao, Yuan Meng, Zhang Bowen

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With the rapid development of the data center industry, achieving low energy consumption and low costs has become crucial. Rational energy configuration and scheduling in Data Center Integrated Energy Systems (DC-IES) have emerged as significant challenges. This study utilizes multi-energy coupling scheduling technology to design an integrated energy system for data centers. With the economic costs of data centers as optimization objectives, an operational model for the DC-IES was established. A two-stage optimization method was utilized to optimize both the capacities of various devices and the scheduling strategy for the integration of source-grid-load-storage operations, thus enhancing energy utilization efficiency. The effectiveness of the model was verified using a railway data center as a case study. The constructed DC-IES achieved an annual cost savings rate of 20.10% and a reduction in carbon dioxide emissions of 2,590 t.
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Calculation and Aging Diagnosis of Hybrid Equivalent Circuit Model for Oil-paper Insulation System

linzhiyong, pengmingcheng, lironghua, suruohang, lvzhisheng

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Aiming at the limitations of the extended Debye circuit in the diagnosis of oil paper insulation aging, an improved hybrid equivalent circuit is proposed to characterize the polarization response characteristics of oil paper insulation media. The interface polarization branch is added to the extended Debye model to characterize the interface reaction between complex media. The characteristic parameters are solved using particle swarm optimization algorithm and combined with on-site testing to verify the reliability and conformity of the hybrid circuit, Simulate and analyze the impact of parameter changes in hybrid equivalent circuits on the polarization spectrum of the recovery voltage. The research results indicate that with insulation aging becomes more severe, hybrid circuits are closer to on-site measured data compared to extended Debye circuits; The time constant and resistance value will decrease, while the capacitance value will increase; The changes in small time constant, medium time constant, and large time constant correspond to the front, middle, and terminal parts of the recovery voltage polarization spectrum, respectively. This provides a more accurate analysis basis for evaluating the aging status of transformer oil paper insulation, and has certain reference and application value.
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A Hybrid Particle Swarm Optimization Algorithm for Hybrid Flowshop Scheduling Problems with Multiprocessor tasks

xuanhua, zhangzhengwei

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In order to handle that one production task simultaneously requires multiple processors to process it,multiprocessor task scheduling in a multi-stage hybrid flowshop with transportation times is proposed.This problem has been shown to be NP-hard. For this, an integer programming model is constructed with the optimization objective of minimizing the maximum completion time (makespan).A mixed discrete particle swarm algorithm is developed combined with an improved particle swarm algorithm, a modified genetic algorithm and a simulated annealing algorithm. Firstly, the relevant behaviors of particle swarm algorithm are improved to avoid the premature convergence of this algorithm. Next,crossover and mutation operators of genetic algorithm are introduced to further enhance the excellent individuals in the particle swarm algorithm and genetic algorithm. Finally, a simulated annealing algorithm isapplied to perform local search for the obtained particle swarm so as to get solutions with higher quality. The comparison and analyses between the proposed algorithm and some existing algorithms show that the developed hybrid particle swarm algorithm has better performance.
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Prescribed Performance Congestion Control for TCP/AQM Network Systems

YIN Chun-wu, Wu Jianxiang

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To solve the problem that the parameter setting of the prescribed performance function depends on the initial tracking error value, a predefined time convergent sliding mode adaptive controller is designed for transmission control protocol (TCP) network systems with arbitrary initial state values, so that the real-time queue length tracking error of TCP network systems converges to zero within a predefined time and satisfies the prescribed performance function constraints. A tracking error conversion function is introduced to convert the queue lengthtrajectory tracking error with an arbitrary initial position into a new variable with an initial value at the origin, allowing the parameters of the prescribed performance function to be set arbitrarily in advance. A predefined time convergence sliding surface is designed, following, a predefined time convergent Lyapunov stability criterion is constructed, based on this stability criterion, the convergence time of close system can be set arbitrarily, and the upper bound of convergence time independent of the initial value and control parameters of the system. The hyperbolic tangent function approximates the control saturation constraint and converts the hyperbolic tangent function into a linear function with respect to the unconstrained control input variables; An adaptive Extreme Learning Machine(ELM) approximates the uncertain part of a TCP network system. Combining prescribed performance control and predefined time control methods, a sliding mode adaptive congestion controller with preset convergence time is designed. Numerical Simulation of TCP/AQM network congestion control with composite interference verifies the effectiveness and strong robustness of the algorithm.
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Wind speed and direction measurement method and system based on wind pressure difference principle

LIU Yanqing, ZHU Meilin, JIANG Xingliang, SU Zhan, JIANG Lihua

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In order to measure the wind speed and direction of natural wind accurately, a wind speed and direction measurement method is proposed based on the principle of wind pressure difference. According to the surface pressure distribution curve of subcritical flow around the cylinder, the circumferential array distribution of six cylindrical pipes is designed. The dynamic pressure of six cylindrical pipe orifices is measured by six high-precision differential pressure sensors, and the maximum value and the maximum value of the adjacent pipe are selected to calculate the wind speed and direction. In addition, the measurement results of anemometer, cup anemometer and ultrasonic anemometer are compared in the natural environment. The results show that the anemometer designed in this paper has the advantages of fast response, high precision, large range, intelligence and long working time, which is suitable for the measurement of heavy wind direction in the field test environment.
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Application of smoke integral-multi-dimensional multi-box model in atmospheric pollutant accounting

ZHANG Fei, GAO Jiayuan, XIAO Yawen, WANG Chao, Ye Zhihong

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Accurate accounting of atmospheric environmental capacity is beneficial for optimising industrial structure and revealing the development potential of industrial park, but it is difficult to achieve accurate prediction with a single model. To address this issue, taking an industrial park in Chongqing as an example, a smoke integral multi-dimensional multi-box model was constructed based on the environmental parameters collected in the park, and the atmospheric environmental capacity of the industrial park was evaluated. Results indicate that the atmospheric environmental capacity calculated by the model generally exceeds the current pollutant emissions, confirming that there remains potential for further development in the park, even with existing pollutant emission controls. The discrepancies between the model's results and those derived from the modified A-value method are minimal, demonstrating the reliability and accuracy of the smoke integral multi-dimensional multi-box model, thus it is shown that this method can be effectively applied to the calculation of atmospheric environmental capacity. Finally, by combining the calculation results with the current pollutant emission characteristics of the park, optimization suggestions are provided for the planning and development of the industrial park.
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Internal corrosion prediction for non-Markov Wiener processes considering measurement errors

CHEN Jiexue, LONG Zhendong, LIU Han, TIAN Hongjun, DONG Shasha, HE Quan, YIN Aijun

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The corrosion evolution behavior of oil and gastransportation pipeline is complicated, and sufficient data on corrosion influencing factors is difficult to obtain during actual operation. Additionally, the traditional empirical model exhibit significant errors in the long-term predictions. In order to more comprehensively characterize the dynamic characteristics of memory effect and measurement random error of pipeline corrosion Process, and accurately predict the corrosion depth of pipeline inner wall, a non-Markov Wiener Process prediction model is proposed considering the dual influence of measurement error and memory effect. The unknown parameters of the model are estimated and updated by maximum likelihood estimation and Bayesian inference. Based on the theory of weak convergence and the definition of first reach failure time, the approximate analytical formula of pipeline corrosion depth distribution is derived to achieve the prediction of pipeline corrosion depth. Finally, the corrosion monitoring data of the inner wall of Tiangao Line B section in Chongqing Gas Mine is taken as an example to verify theeffectiveness of the method.
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Study on stage flow characteristics and bubble behavior of wide particle size distribution particle system

Zhu Kuisong, Zhengzhong, Jian Siling, Xu Yuzhong, Yang zhengjiang, Cao Li, Zhu Jiaqing, Yangjian

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To explore the characteristics of staged fluidization caused by segregation in the fluidization process of iron ore powder with Geldart-B particles, the experimental study on bubbling fluidization of iron ore powder with average particle size of 350 μm was carried out in a two-dimensional fluidized bed reactor. The characteristics of staged fluidization of bubbling fluidization of iron ore powder with single particle size distribution were obtained, and the causes of staged fluidization were explained in combination with the pulverization effect. Then, a staged fluidization experiment was carried out on a three-component glass bead system. The standard deviation of bed pressure drop was used to identify the staged fluidization process. Finally, the bubble behavior characteristics of glass beads and iron ore powder systems with the same average particle size in different fluidization stages were compared. The results show that the pulverization effect of iron ore powder in the fluidization process will lead to an increase in the standard deviation of particle size distribution. The particle segregation in the fluidization process leads to different bubble behavior characteristics, which makes the bed show staged fluidization characteristics. Combined with the characteristics of staged fluidization and the standard deviation of bed pressure drop, it is found that the bubble behavior in different fluidization stages leads to the change of standard deviation, and the standard deviation of bed pressure drop in stable fluidization stage tends to be fixed. The pulverization effect in the fluidization process of ore powder leads to the increase of the standard deviation of particle size distribution. In the stable fluidization stage, the average equivalent diameter of bubbles increases, and the longitudinal velocity and transverse velocity of bubbles also increase.
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Research on spectral element model of reinforced concrete T-beam

SUN Rui, HUANG Shoufu, HU Zheng, LIU Gang

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Model updating is an important work in structural damage identification, mostly using finite element model, but refined modeling usually leads to computational inefficiency. In this paper, an effective spectral element model is proposed for reinforced concrete (RC) T-beam. Firstly, the displacement governing equations were derived by using Hamilton principle, the displacement field was transformed from time domain to frequency domain using Fast Fourier Transform (FFT). The spectral element model of RC T-beam was established, and a nonlinear static calculation framework was developed. In order to verify the validity of the model presented in this paper, a RC T-beam specimen was experimental tested and numerical simulation was carried out using finite element model. Finally, the structural damage identification based on model updating was carried out by using the proposed spectral element model. It shows that only 34 spectral elements were used to complete the calculation, thus, the computational efficiency of the spectral model is much higher than finite element model. Fast convergence can be achieved by using the spectral element model. In summary, the proposed spectral element model can be applied in model updating, which provides a reliable tool for structural health monitoring and damage identification.
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Low-cycle fatigue life analysis and prediction of M24 high-strength bolts

JIAO Jinfeng, SHI Yuchen, XIA Wenyuan, CHEN Pengcheng, LU Guoyun

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To investigate the low-cycle fatigue damage characteristics and life patterns of high-strength bolts used in assembled steel structures, a low-cycle fatigue test under constant-amplitude axial tension was conducted on 15 M24 Grade 10.9 high-strength bolts using a self-designed loading apparatus. The fatigue failure characteristics of typical high-strength bolt specimens under different displacement loads were analyzed. Additionally, the applicability of the power law function and the Coffin-Manson formula for predicting the low-cycle fatigue life of high-strength bolts was explored. The result shows that increased displacement load intensifies stress concentration in high-strength bolts, resulting in rougher fracture surfaces, reduced fatigue crack propagation area, and enlarged instant fracture area. The primary failure location of the bolts is at the first thread where the bolt and nut make contact. There is no significant monotonic relationship between low-cycle fatigue life of high-strength bolts and cyclic displacement amplitude, as similar fatigue life can correspond to different displacement loads. When the displacement amplitude approaches the ultimate load-bearing capacity, the bolt failure state resembles that of a static tensile failure. Furthermore, the power law function formula predicts fatigue life more accurately than the Coffin-Manson formula, especially when δ/δy is less than 2.45.
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Design and implementation of driving circuit of 1mm cylindrical piezoelectric ultrasonic motor

likangkang, wangyufei, zhanghaibin, chenyuanbo, wangguangqing

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The performance of driving circuit is very important for the stable and high precision operation of micro piezoelectric ultrasonic motor. Aiming at the low voltage drive and high speed operation requirements of 1mm micro cylindrical piezoelectric ultrasonic motor, a transformer inverter booster push-pull drive circuit based on Digital Signal Processing (DSP) 28335 chip is designed. The circuit uses DSP 28335 chip as the core to generate four Pulse Width Modulation (PWM) waves. After the PWM wave drives the four MOSFET switch tubes in pairwise alternating conduction, the inverter voltage boost and power amplification are carried out through the transformer, and then the sinusoidal wave with the same amplitude and 90° phase difference is obtained after the LC matching circuit filtering to drive the 1mm ultrasonic motor to rotate. The detailed analysis and parameter design of the hardware and software of the drive circuit are made. The simulation and experiment results show that the output voltage of the drive circuit based on DSP 28335 chip can be adjusted in the range of 0-100V, and the frequency can be adjusted in the range of 15kHz-50kHz. The no-load speed of the piezoelectric ultrasonic motor increases linearly with the increase of the excitation voltage, and reaches 480rpm under the action of 22kHz and 50V respectively, which meets the driving requirements of 1mm cylindrical piezoelectric ultrasonic motor.
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Study on static mechanical properties of Granite-Goncrete composites after High Temperature

QI Wenchao, HE Tong, Ran Qiushuo, Guo Hao, LIULEI

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Static uniaxial compression tests were carried out on five groups of GCC samples with different rock proportions (0.4, 0.5 and 0.6) after treatment at 25 °C, 200 °C, 300 °C, 400 °C and 500 °C, as well as granite and concrete monomers. In order to explore the static compressive mechanical properties and failure evolution law of GCC after high temperature, the compression fracture of the connection surface of the GCC specimen was tested by SEM scanning electron microscope. The results show that the peak strength, elastic modulus and mass of GCC specimen are between concrete and granite, and are positively correlated with the proportion of rock. In the deterioration of strength, the concrete part dominates, the total stress-strain curve gradually slows down, the suddenness and brittleness of failure weaken, and the graduality and plasticity gradually increase. With the change of temperature, the failure modes of the assemblage are different, and the "Y" type shear failure of concrete and granite splitting failure are the main ones, and the number of microcracks increases during failure. The results of this study can provide some theoretical support for the safety assessment of underground engineering after fire, and also lay a certain theoretical foundation for engineering design and monitoring in complex environments.
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Robust layout optimization of stiffened plate structures considering load uncertainty

Wang Xuan, Sheng Zilu, Chen Xiang, Li Zhixuan

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The distribution of stiffeners in the stiffened plate structure seriously affects its structural performance. At present, most of the work on the design of the stiffened plate structure is carried out under deterministic load conditions, where the effect of load uncertainty on the structural stiffness is ignored. This paper proposes a robust structural layout optimization method for layout optimization problem of stiffeners in stiffened plate structures considering load uncertainty, and realizes the simultaneous optimization of the layout and size of stiffeners. A robust layout optimization model is established based on the ground structure method, with the radius of the circular section beam representing the stiffener as the design variable, the mass of the entire structure as the constraint, and the linear weighted value of the expected and variance of the structural compliance under uncertain loads as the objective. The analytical sensitivity formula of the expectation and variance of the structural compliance and the mass constraint with respect to design variables are deduced in detail. The method of moving asymptotes is adopted to solve the robust layout optimization problem. Finally, two examples are performed to verify the effectiveness of the proposed method.
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Event-triggered model predictive control of building thermal environment

QUAN Yubo, LI Yanxin, GUO Jiawen, XIONG Shuting, HE Ning

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Aiming at the problem of computational redundancy and communication burden in model predictive control of indoor thermal environment, an integral-type event-triggered control strategy is proposed. Firstly, a simplified building resistant-capacitance (RC) thermal network model is established based on the equivalent circuit method, considering the influence of the temperature of adjacent hot areas, and the accuracy of the model is verified. Then an integral-type event-triggered mechanism (ITETM) based on state error was proposed. On this basis, an integral-type event-triggered model predictive control (MPC) method based on RC thermal network is proposed. Finally, the performance of the proposed control method is verified by the co-simulation experiment of EnergyPlus and MATLAB. The results show that the proposed control strategy can effectively reduce the calculation and information transmission times of the optimization problem, and reduce the energy consumption of the building while ensuring the indoor temperature comfort.
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SS-UDANN: Spatiotemporal Feature Analysis Method for High-Dimensional Complex Data

LIAN Lian, MA Wei, ZONG Xue Jun, HE Kan, SUN Yi Fei, NING Bo Wei

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To address the limitations of existing methods that only focus on temporal or spatial features, this study proposes a novel approach for analyzing high-dimensional complex data using spatiotemporal features. The method, named Spatiotemporal Sparse Regularization Convolutional Autoencoder Unsupervised Domain-Adversarial Neural Network (SS-UDANN), employs a Sparse Regularization Convolutional Autoencoder (SRCAE) as an unsupervised feature extractor and incorporates an enhanced Domain-Adversarial Neural Network (DANN). A lightweight cross-dimensional Spatial Channel Attention (SCA) mechanism is integrated to extract spatiotemporal features efficiently while keeping computational costs low. Maximum Mean Discrepancy (MMD) is applied to regularize the feature extractor and domain discriminator, facilitating the extraction of domain-invariant features for effective data augmentation. Validation of SS-UDANN on the CICIDS2018 dataset for industrial network anomaly detection shows an accuracy of 98.66%. Additionally, the model achieves 95.39% accuracy when applied to data from a laboratory oil and gas full-process attack-defense testbed, further confirming the method"s effectiveness and demonstrating its potential for broader application in data processing.
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Method on Robot Path Optimization Based on Multi-objective Constraints

nieqingbin

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For mobile robots in path planning, there exist problems such as blind search in the initial stage, excessive number of turns, poor path smoothness, and easy trapping in local optimum. A robot path optimization strategy based on multi-objective constraints is proposed. This strategy is an improvement on the traditional ant colony algorithm. Firstly, the A* algorithm is introduced to enhance the pheromone concentration of adjacent feasible paths, reducing the blindness of the initial search and improving the convergence speed of the algorithm. Secondly, the distance heuristic function is improved by adding the distance relationship between the candidate node and the target node to enhance the guidance of the target node to the global optimal path. Thirdly, a turning heuristic function is proposed. This function is composed of the obstacle concentration constraint function, the turning constraint function, and the smoothness constraint function. The turning heuristic function is added to the transition probability formula to guide ants to move towards paths with fewer turns, shorter distance and smoother. Finally, the pheromone evaporation factor is improved, effectively balancing the weights of local search and global search. The pheromone update rule is also improved, and a reward and punishment mechanism is set for pheromone update from two aspects of path length and the number of turns, reducing the redundancy of pheromone and improving the algorithm efficiency. Meanwhile, the pheromone concentration is limited to prevent the algorithm from falling into premature problems. Simulation experiments show that under the same experimental conditions, compared with other algorithms, the improved algorithm has a shorter running time, a shorter optimal path length, a smoother path, and a faster convergence speed.
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Load Balancing Mechanism for SDN Multi-Controller Switch Migration

Li Guoping

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In response to the issue of load imbalance caused by the multi-controller architecture in complex Software Defined Network (SDN) structures within large data centers, a switch migration strategy based on reinforcement learning is proposed. First, the switch migration problem is modeled as a combinatorial optimization problem, taking into account both load balancing and the distribution of controller loads. Next, we optimize the Soft Actor-Critic (SAC) algorithm by incorporating a priority migration mechanism based on a SumTree, aiming to maximize improvements in load balancing while employing a strategy that incurs minimal migration overhead. A global control plane connection is established through a server to facilitate switch migration based on load conditions, ultimately achieving load balancing among controllers. Simulation results indicate that this strategy effectively realizes load balance according to load states. In a simple load environment, load balancing improved by 17.34%; in a complex load environment, the performance enhancement was even more significant, reaching 74.45%, while also demonstrating certain advantages in terms of migration overhead.
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Automotive seat vibration comfort evaluation based on subjective and objective test

GAO Kaizhan, ZHU Lijiang, ZHANG Zhifei, CHEN Yu, XIE Jie, HE Meishuang

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For meeting the requirements of comfort evaluation between the same level of automotive seats under vibration conditions, the subjective evaluation, body pressure distribution, and acceleration tests related to vibration comfort were conducted on three automotive seats, A, B, and C with 12 test participants under low-frequency vertical excitation with six different magnitudes (from 0.5 to 20 Hz with six magnitudes 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 m/s2). Based on the analysis of body pressure distribution and acceleration test results, three objective indicators were obtained, such as the root-mean-square of average pressure changing rate, the root-mean-square of normal force changing rate and the root-mean-square of weighted acceleration. The correlation analysis was carried out on subjective and objective indicators by applying the non-parametric statistics method for verifying the consistency of subjective and objective evaluation results. Finally, the vibration comfort evaluation between the three automotive seats was realized by comparing the subjective and objective evaluation results.
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Lightning Impulse Flashover Characteristics of Inverted T-shaped Contaminated Insulators

HU Qin, XIE Dexin, CHEN Xuye, WU Changqing, JIANG Xingliang

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The inverted T-shaped arrangement of insulator strings can improve the AC and DC flashover voltage of insulator strings in polluted and icing environments, but its flashover characteristics under lightning impulse voltage lack research. In order to investigate whether the inverted T-shaped arrangement effects the lightning withstand level of insulator strings, this study used LXY-70 glass insulators as samples to explore the lightning impulse pollution flashover characteristics of the inverted T-shaped insulator strings under different arrangements and salt densities. The electric field distribution was also simulated. The results show that the lightning impulse flashover voltage of the inverted T-shaped insulator strings is inversely proportional to the salt density. The electric field strength in the horizontal tension segment is lower, with less distortion, which is not conducive to the development of local electric arcs. The flashover voltage under positive polarity and negative polarity lightning strikes is increased compared to the suspended arrangement. The percentage increase in flashover voltage with a certain creepage distance increases with the increase in horizontal string length, but the magnitude of increase is small. The inverted T-shaped arrangement can slightly enhance the lightning withstand level of insulators. These findings can provide some reference for the practical application of the inverted T-shaped arrangement in transmission lines.
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A two-stage route planning algorithm for vehicle-mounted UAVs in large areas

LiXiaohui, Liyaxin, ZhouRui, ZhaoYi, DongYuan, JinYinli

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Unmanned aerial vehicles (UAVs) have been widely used in various fields and have the advantages of low safety factor and low cost. However, due to the limited endurance of the UAV, it is impossible to reach a long distance, a new solution is to use the vehicle to carry and launch the UAV, that is, the collaborative way of the UAV and the vehicle, in order to complete the total time of the minimum as the goal. In this paper, a two-stage algorithm is proposed to solve the path planning problem of UAV-vehicle cooperative operation. In the first stage, the target area is divided using a clustering algorithm to determine the distribution of vehicles. In the second stage, the traditional teaching optimization algorithm HTLBO is designed and improved to improve the search efficiency, and the route of the UAV is obtained in each target area to ensure the optimization of the route. Finally, the experimental results compared with other comparison algorithms show that the vehicle-UAV joint operation model and HTLBO algorithm are feasible and robust, and provide some ideas and references for complex dynamics in various large-scale areas.
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Ciphertext-Policy Attribute-Based Encryption scheme for smart grid data based on Chinese national cryptography

MAO Rui, ZHANG Xiaoyun, LAI Te, ZHANG Chao, DUAN Lianhong, ZHAN Wen, PENG Anqing, LIU Siyi, FAN Yu, XIA Xiaofeng

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Smart grid is a new power system framework that combines bidirectional communication technology and various electrical devices. The business data in the smart grid contains sensitive and private information, and thus fine-grained access control needs to be directly implemented at the data level. This paper proposes a Ciphertext-Policy Attribute-Based Encryption (CP-ABE) scheme for smart grid data based on Chinese national cryptography. By adding attribute related components to the system master key, system public key, and user secret key of the SM9-IBE algorithm, and introducing an access structure in the form of threshold tree to the ciphertext, the SM9-IBE algorithm is extended to support fine-grained access control in the CP-ABE scheme, which thereby encrypts the SM4 block cipher key. Only users who comply with the access policy can decrypt and obtain this symmetric key. Moreover, the scheme can resist collusion attacks.
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A Review on Dynamic Threshold Voltage Drift in SiC MOSFETs

Jiang Huaping, Tang Lei, Zhong Xiaohan, Xiao Nianlei, Zhao Ke, Liao Rinjin

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Silicon carbide (SiC) is a wide bandgap semiconductor with a critical breakdown electric field approximately an order of magnitude higher than that of silicon. This enables SiC-based MOSFETs to extend their voltage and current ratings to cover those of silicon-based IGBTs. Unipolar MOSFETs have a significant advantage over bipolar IGBTs in terms of switching losses. However, the silicon carbide MOSFET has a dynamic threshold drift problem, which is one of the key factors leading to the Tesla electric vehicle recall. This paper reviews recent research on the dynamic threshold voltage drift of SiC MOSFETs from both domestic and international sources. The drift behavior of SiC MOSFETs under different stresses and the physical mechanisms inducing dynamic threshold voltage drift are analyzed, and corresponding solutions are proposed.
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Tang Chao, Liu Zewei,Wang Tianqi, Hu Chunqiang

Tang Chao, Liuzewei, Wang Tianqi, Hu Chunqiang

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Despite its ability to leverage local data for machine learning model training while preserving privacy, recent studies have unveiled challenges related to fairness and gradient privacy leakage in federated learningBased on this, aiming at the privacy protection challenges in federated learning, a fair and secure federated learning algorithm based on differential privacy is proposed. The algorithm sets the privacy budget based on the amount of client-side data and adjusts it according to the gradient change rate. During the training of local models on the client side, differential noise is added to the gradients to protect the privacy and security of the information. Experimental results show that, with an appropriately set privacy budget, the algorithm's performance can achieve a balance between accuracy, fairness, and privacy protection
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Simulation study of multi-array scanning imaging with dynamic current fields

JIN Jianhui, DU Xingmei

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This study focuses on underwater imaging and detection technology, using active current field and array scanning technology to enhance imaging performance. In order to solve the problems of low resolution, small coverage and poor signal-to-noise ratio in traditional static current field imaging, the dynamic current field array scanning technology is proposed. By dynamically adjusting the position of the array transceiver point, high resolution and large coverage imaging is achieved. In this study, a suitable imaging algorithm is selected to achieve clear imaging of the underwater target object, and through the splicing and fusion of multiple scanning data, the noise is effectively filtered out to improve the clarity, accuracy, signal-to-noise ratio and imaging stability of the image. Dynamic scanning imaging has high flexibility and adaptability, and the position of the transceiver pole can be adjusted according to the actual situation to meet different imaging needs and environmental changes. Simulation experiments explore the imaging effect of three conventional scanning modes, and propose two imaging methods of complementary zero fusion and splicing for the two receiving modes, and finally determine the optimal scheme for different applications through the experimental results. This study provides important theoretical support and experimental basis for the development of underwater imaging and detection technology.
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Occurrence and transformation of metal elements in the process of carbon reduction of high chromium vanadium titanomagnetite

Zhu Kuisong, Cao Li, Wang Jun, Zeng Fuhong, Zhao Yingtao, Liu Tiantian, Cheng Xiangli

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The high chromium vanadium titanomagnetite in the Honggenan mining area of Panzhihua is a vanadium titanomagnetite resource that will be developed and utilized. In this paper, through the thermodynamic analysis of carbon reduction of high chromium vanadium titanomagnetite and the high temperature carbon reduction experiment, the phase composition, microstructure morphology and element content in different phases of the reduction products were studied. The occurrence, transformation and enrichment of metal elements Fe, Ti, V and Cr in high chromium vanadium titanomagnetite at different reduction temperatures were analyzed in detail, as well as the metallization rate and reduction degree of the reduction products. The results show that under the condition of 1.3 molar ratio of carbon to total oxygen in iron ore. The transformation law of the occurrence form of the main metal elements in iron ore is: Fe₃O₄ → FeO → Fe；Fe₂TiO₅ → Fe₂TiO₄ → FeTiO₃ → (Mg, Fe)Ti₂O₅；FeO.V₂O₃ → V₂O₃ → VO；FeO.Cr₂O₃ → Cr₂O₃ → Cr；When the temperature is higher than 1250 °C, the Cr oxide is reduced to metal Cr and dissolved in the metal phase. V oxide is not reduced to metal V. With the increase of temperature, the metallization rate and reduction degree of Fe increase. When the temperature reaches 1350 °C, the metallization rate of Fe reaches 89.01 % and the reduction degree reaches 90.53%.
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Research on carbon emission calculate and influencing factors of railway track-laying base

BAO Xueying, REN Haitao, LIU Beisheng, LI Hui, LI Zilong

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As an important large-scale temporary project of railway engineering, the carbon emission of track-laying base is the source of carbon emission that cannot be ignored in the materialization stage of railway engineering. The carbon emission factor method was used to establish the carbon emission measurement model in the life cycle of railway track-laying base. Then, the carbon emission characteristics of track-laying base were extracted as influencing factors, and the key influencing factors were identified by feature importance ranking. Finally, the interpretable machine learning model was used to visualize the contribution of key influencing factors to carbon emissions, and analyze the impact mechanism of key influencing factors on carbon emissions. The results show that the total life cycle carbon emission of the track-laying base is 4825.134~15122.059t. The carbon emission ratio of building materials in the production stage of rail laying base was the highest (72%-86%). According to the ranking results of the importance of influencing factors of track laying base, the five key influencing factors are identified as base area, foundation treatment method, road hardening method, mechanical track length and stock track length. The influence of key factors on carbon emissions was analyzed by SHAP summary diagram and dependency scatter diagram. The research results can provide theoretical basis for the research on carbon emission reduction of railway track-laying base.
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Study on optimization of working line layout and development mode of high-capacity open-pit coal mine in narrow mining district

zhaojingchang, wanghanshu, houpeng, bairuncai, renshihao

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Open-pit mining is one of the important mining methods of coal resources. Ensuring the production capacity of open-pit coal mines is of great significance for ensuring the stable supply of coal and maintaining national energy security. In this paper, taking Haerwusu Open-pit Coal Mine as an example, aiming at the problem of how to ensure the realization of 35Mt/a high design capacity under the special conditions of shorter working line length and narrower mining district width after the working line of the first mining district retracts to the mining right scope, based on the principle of technical feasibility and economic rationality, considering the influence of working line length on production stripping ratio, stripping haulage distance and raw coal production capacity, a mathematical model with the lowest annual stripping total cost as the goal was established, and the economic and reasonable working line length was determined to be 1620m～2315m.On this basis, further combined with the production capacity and equipment layout scheme of the available mining equipment in Haerwusu open-pit mine, it was determined that the annual average advancing speed of the working line was controlled within the feasible range of 400m～515.25m, and the working line length which can make the production capacity of the mining equipment fully exert was 1820m. Based on the analysis and optimization of the working line length determined by the feasible advancing speed of the working line, the Monte Carlo method was innovatively used to design the working line shape, and three working line layout and development schemes that met the requirements of the working line length and the annual advancing speed limit were proposed. Through the engineering deduction of the three schemes, a CRITIC-TOPSIS comprehensive evaluation model based on the objective weighting method was constructed by selected six key indexes, such as the average production stripping ratio, the weighted average haulage distance and lifting height of stripping, the weighted average haulage distance and lifting height of raw coal, and the average maximum advancing speed of working line. The evaluation results showed that scheme No.2 had the highest degree of closeness to the ideal solution, which can make Haerwusu Open-pit Coal Mine achieve the goal of 35Mt/a raw coal production capacity under the condition of narrow mining district with the best technical and economic benefits.
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Improved multi-objective grey wolf algorithm for optimizing washout motion and experimental verification

Sun Hao, Wang Hui

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The natural cutoff frequency parameter of the filter in the wash-out algorithm is the main factor affecting the wash-out effect, and then affect the motion fidelity of the flight simulator. In order to obtain the optimal parameters of the natural cut-off frequency of the filter, an improved multi-objective grey wolf algorithm is put forward to find the most suitable filter parameters. The Logistic-tent mapping is used for initialization to improve the diversity of the population. The belief of the differential evolution algorithm is combined to the multi-objective grey wolf algorithm for iterative optimization. The nonlinear control parameters and the introduction of the inertia weight strategy are used to update the population position, which effectively balances the algorithm"s global search and sectional development abilities. The objective function is built by using three evaluation indicators of the wash-out algorithm, and use the fuzzy membership function to get the best solution. The simulation and experimental results demonstrate that the improved multi-objective grey wolf algorithm reduces the 1.23s phase delay and corrects the sensory peak compared with the classic wash-out algorithm, while saving 18.5% of the working space of the motion platform, and the wash-out effect is more ideal.
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Simulation study of underwater controllable array imaging based on active electric field

DU Xingmeia, JIN Jianhuia

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As the demand for marine resources continues to grow, efficient and accurate underwater detection techniques have become particularly critical. Traditional detection methods have their own advantages, but they are often limited in complex and dark underwater environments. Underwater active electric field detection technology has unique advantages in this environment. In this paper, a controlled array transceiver-integrated imaging detection method based on active electric field is proposed, aiming to overcome the limitations of the existing technology and improve the efficiency and accuracy of underwater detection. The approach achieves efficient imaging of underwater objects by dynamically adjusting the transmitting and receiving points in the array, finely controlling the current field, and processing the received signals. In this study, the theoretical analysis of the calculation method of the field strength at the receiving point of the array and the electric field perturbation of the obstacle is carried out, and the effects of the two types of electrode arrangements on the imaging effect are compared by simulation experiments. The experimental results show that the centrosymmetric arrangement has better performance in detection, which provides a new technical perspective for improving the efficiency and accuracy of underwater detection.
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Smart Contract Vulnerability Detection Method Based on MixStyle Transfer

liMin, GeFuJiang, YuanHaiBing, JiangLiBiao, ShangYunPeng

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The study proposes a smart contract vulnerability detection method based on MixStyle transfer, aiming to solve the problem of insufficient datasets and the inability to effectively detect unknown vulnerabilities when new vulnerabilities emerge in smart contracts. The method first extracts the abstract syntax tree from the smart contract source code and uses graph attention network to capture the dependencies and information flow between nodes; then, the Maximum Mean Discrepancy is used to achieve effective knowledge migration from old vulnerabilities to new ones, thus increasing the amount of data for deep learning model training; finally, the MixStyle technique is incorporated into the classifier to enhance the model"s generalization ability and improve the accuracy of identifying novel vulnerability types. The experimental results show that the method outperforms BLSTM-ATT, BiGAS, and Peculiar methods in F1, ACC, and MCC metrics for the detection of the four vulnerability types.
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中图分类号:TU528；S277.7 ? 文献标识码:A

Li Hao, zhang zhuosen, Guo Haolong, Sun Changwei

Abstract: (1267) HTML (0) PDF (0.00 ByteKB) (0)

In order to improve the utilization rate of aeolian sand,this article aims to study the influence of calcium carbonate whiskers with different volume content on the compressive and split tensile strength of aeolian sand concrete.Observe the bonding morphology of calcium carbonate whiskers and cement paste from a microscopic point of view through scanning electron microscopy and nuclear magnetic resonance,and analyze its mechanism of action, based on the analysis of the test results and put forward the theoretical relationship between compressive strength, split tensile strength and curing age. The test results show that adding an appropriate amount of calcium carbonate whisker can effectively improve the pore structure and mechanical properties of aeolian sand concrete. When the aeolian sand content is 60% ,The optimum volume content of calcium carbonate whisker for compressive strength and splitting tensile strength is 0.15% and 0.2% respectively. The proposed theoretical model is in good agreement with the experimental data, and can better predict the strength value under age.
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Heat transfer law and experimental study of deep drilling supercritical CO2 heat exchanger

DENG Guangzhe, Yu Fei, Yuan Chao

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Under the background of the “dual carbon” target, exploring new paths for industry restructuring to reduce carbon emissions and increase efficiency, and developing new high-quality productivity for CO2 high-energy utilization are hot topics in CO2 emission reduction research. To determine the mechanism of CO2 phase change induced cracking and expand the application of CO2 phase change induced cracking engineering. Safety and environmental advantages demonstrated based on the multiphase change characteristics of CO2 and energy utilization, a new type of deep drilling supercritical CO2 heat exchanger is proposed. Taking CO2 at 25 ℃ as the research object, a simulation scheme was designed using fluid simulation to simulate different water temperatures as heat carrying fluids, revealed the gas-water heat transfer mechanism under the coupling effect of hydrothermal fluid and CO2.The reliability of heat transfer in CO2 heat exchangers has been verified through experimental analysis. The results that as the temperature of the hydrothermal fluid increases, the heating rate of CO2 is positively correlated with the temperature of the hydrothermal fluid. For every 1℃ increase in water temperature, the temperature of CO2 increases by 0.9℃, the temperature of the water stream decreases gradually with the increase of CO2 heat absorption, dissipation temperature of hydrothermal fluids is proportional to CO2 absorption temperature. The heat transfer coefficient of hydrothermal fluids increases from 1790W/m2?K to 2090W/m2?K. The heat transfer coefficient of hydrothermal fluids gradually increases with the increase of initial water temperature, The heat transfer coefficient of CO2 is directly proportional to the heat transfer coefficient of hydrothermal fluids. The CO2 phase change heat absorption temperature showed an exponential growth trend with the increase of water temperature, and the liquid CO2 heat transfer coefficient was inversely proportional to the trend of the gas CO2heat transfer coefficient. The maximum pressure of CO2 inside the pipe increased from 131MPa to 199MPa, the pressure change goes through a phase of thermal expansion of liquid CO2, a phase of thermal expansion of gasCO2 a phase of phase change energization, and a phase of pressure stabilization. The heat absorption of CO2 is positively correlated with the initial water temperature, and the power of the water flow heat source gradually increases with the increase of water temperature. The power of the water flow heat source is proportional to the water temperature. The effectiveness of the deep drilling supercritical CO2 heat exchanger was verified through the establishment of correlation equations and experimental analysis, providing a basis for the design of supercritical CO2 heat exchangers.
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Coalescence or bounce criterion of droplet collision on superhydrophobic surface

LI Ke, WANG Jishuo, YUAN Weifeng

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Exploring the effect of droplet velocity on the behavior of binary droplets of the same size colliding head-on on a superhydrophobic surface, pure water droplets were used as the research object. The collision process of droplets was observed with a high-speed camera, and a theoretical model of the critical conditions for coalescence or bouncing after collision was established. The model can predict the critical velocity for coalescence or bouncing after droplet collision. The results show that with the increase in droplet velocity, the probability of droplet coalescence after collision increases; the larger the droplet size, the lower the critical velocity for coalescence or bouncing after collision. During the deformation process of droplet collision, the internal pressure increases beyond the limit that surface tension can withstand, resulting in droplet coalescence. The theoretical method established matches the experimental results well. The proposed theoretical model can be used to predict the behavioral changes of droplets at a certain velocity, achieving the purpose of controlling droplet collision behavior, and can be applied to fields such as droplet manipulation, droplet sensing, and microreactors.
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Research on the impact of geometric parameters on the impact of continuous barrier band characteristics of cyclical wave impending blocks

Wang Haiyang, Yin Hongshan, Xu Ruhang, Wang Zhu, Yang Yansong

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In order to explore the impact of geometric parameters on the characteristics of the continuous barrier gap characteristics of cyclical ripple blocks, based on the theory of sound -crystal band gap, the finite element method is used to calculate the concrete as the base, the rubber as the parcel layer, and the natural soil as the core body as the core body. The band characteristics of the cyclical wave resistance block, which in turn, design the orthogonal experiment to analyze the influence of geometric parameters on the completely band, and combine the indoor model experiment to verify the effectiveness of the band"s characteristics. Results show that the effects of single cell constant, the thickness of the package layer and the core body have a greater impact on the width of the band, while the effect of the core shape is not obvious; The thickness of the parcel layer and the shape of the core; the attenuation domain of the experiment is high and the theoretical completely gap range is high, which confirms the band characteristics of the continuous barrier of the periodic wave block.
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Parallel avalanche shunt characteristics of silicon carbide MOSFETs

Zhong Xiaohan, You Tongsheng, Jiang Huaping, Ma Shaobo, Tang Lei, Yang Pengzheng

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Silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) are favored by power electronics engineers for their excellent performance. However, the dynamic threshold voltage drift caused by the poor gate oxide quality of SiC MOSFETs poses a potential threat to their stable operation. Particularly under extreme conditions such as avalanche, the dynamic threshold voltage drift in parallel SiC MOSFETs significantly increases the likelihood of avalanche failure. To investigate the impact of dynamic threshold voltage drift on the avalanche behavior of parallel SiC MOSFETs, a dual parallel avalanche test platform was established. Using the method of separating variables, the avalanche current sharing of parallel SiC MOSFETs with different amounts of dynamic threshold voltage drift was studied. Experimental results indicate that when the threshold voltage difference between parallel SiC MOSFETs is small, the current sharing during avalanche is high. However, when the threshold voltage difference exceeds 0.5V, the current sharing during avalanche is poor, with the device having the smaller threshold voltage carrying more current during both the current rise and avalanche phases. It is believed that the device with the larger threshold voltage captures a significant amount of electrons, leading to a decrease in channel mobility and consequently lower avalanche current sharing.
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Privacy-protecting Personalized Federated Learning Load Forecasting Scheme

ZHAO Ruifeng, QIU Junqi, Lu Xiaohai, LIU Zewei, ZHUANG Huijun, HU Chunqiang

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Addressing data privacy protection in the context of power load forecasting for distribution networks, a user-level load forecasting scheme based on federated learning is proposed, specifically tailored for data privacy safeguarding in user-level load forecasting scenarios. In this approach, multiple smart meters from different households collaboratively participate in the model training process, with each meter training its own personalized model for local, tailored predictions. Furthermore, the scheme integrates an adaptive gradient clipping and noise addition algorithm into personalized federated learning, bolstering the privacy protection capabilities of the solution while minimizing the impact on forecasting accuracy. Experimental analysis demonstrates that this scheme not only safeguards the privacy of power load data but also provides precise power load forecasting for distribution networks, thereby contributing to the stable operation and optimal management of the distribution grid.
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Multi-GNSS Ambiguity Resolution Study based on Different PPP-AR Products

GUO Tianwei, WU Zhiyuan, dongkunfeng, yangmin, zhouxinrui, YANG Zai Song

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For different ambiguity products, this paper introduced the principle and methodology of the PPP-AR methods based on the dual-frequency ionosphere-free combination model, made detailed analysis of the experimental results in terms of four indexes: positioning accuracy, convergence time, the time to first fix and ambiguity fix rate. The results show that: the ambiguity fix solutions of phase bias product and fractional cycle bias product for the single GPS system and single Galileo system experimental schemes are 0.53 cm, 0.54 cm, 1.05 cm and 0.59 cm, 0.58 cm, 1.31 cm, respectively, which are 49.0%, 32.5%, 15.3% and 41.6%, 20.5%, 3.7 % improved compared with the floating solution. The phase bias product is able to improve the convergence time of the single GPS system by 22.9 % from 17.5 min to 13.5 min, but the ambiguity product improves the convergence time of the Galileo system by less than 10 %, the time to first fix was around 21 min and 27 min for the single GPS system and the single Galileo system, respectively. The ambiguity fix rate of each PPP-AR products is above 90 % for the single GPS system, while the ambiguity fix rate of the single Galileo system is around 85 %.. With the addition of the BDS system, the positioning accuracies of the multi-system phase bias products reach 0.45 cm, 0.49 cm, and 1.02 cm, which are improved by 32 %, 34.7 %, 17.1 %, the convergence time is shortened to less than 10 min, and the time to first fix is reduced to around 10 min, and all the ambiguity products can maintain ambiguity fix rate more than 95 %.
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Research on bin packing problem of enterprise logisticsconsidering large size difference of products

LIANG Zhixin, WANG Zhiwei

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To optimize the loading of products in the process of order fulfillment is important to improve the efficiency of the logistics system of enterprises. Aiming at the three-dimensional multiple bin-size bin packing problem with large size differences and strong heterogeneity of products, the size classification strategy was proposed, and a hybrid heuristic algorithm was designed based on it. In the algorithm, firstly, the products were divided into different size types according to the matching degree of products and pallets, and the corresponding loading strategies were designed for different types of them. Then the best fit algorithm was used to select the appropriate cartons for the products. Finally, greedy random adaptive search procedure was used to find the packing plan. Taking the real order as the dataset, the test results show that the proposed algorithm is superior to the traditional three-dimensional packing algorithm, and the layout of the packing plan found by using the size classification strategy is more reasonable, which can provide decision support for similar packing problems.
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Research on Energy-efficient Hybrid Flow Shop Scheduling Based on Artificial Bee Colony Algorithm

ZHANG Hongliang, XU Qiang, YAO Youjie, LIU Qihao, GUO Liqiang

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To address the energy-efficient hybrid flow shop scheduling problem that incorporates sequence-dependent setup time and transportation time constraints, a multi-population discrete artificial bee colony (MPDABC) algorithm is introduced. First, a two-layer encoding strategy is employed to represent a feasible scheduling solution, encompassing job sequencing and machine speed. During decoding, traditional rules are refined to accommodate time constraints arising from machine setup and job transportation. Next, a tournament mechanism partitions the population into multiple subpopulations. Four neighborhood structures are designed to facilitate detailed searches within each subpopulation during the employed bee phase. In the onlooker bee phase, individuals from each subpopulation select subsequent targets based on interaction factors, fostering inter-subpopulation information exchange. To prevent the algorithm from getting trapped in local optima during the scout bee phase, a simulated annealing mechanism is applied. Finally, the MPDABC is evaluated through simulation experiments alongside three other multi-objective algorithms on 24 instances. Comparison results demonstrate the superior search performance and effectiveness of the proposed MPDABC.
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Study on properties of multi-scale fiber reinforced restoration materials for Leshan giant Buddha

WANG Yi, ZHANG Hongbin, YANG Tianyu, WANG Jinhua

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Mixed hammered ash is a kind of repair material with both hydraulicity and air hardening properties used in the restoration of Leshan Giant Buddha. To solve the problems of cracking and peeling caused by the influence of the environment on the repair materials of the head and face of the Buddha, hemp fiber (HF) and Calcium carbonate whisker fiber (CWF) are used to enhance this material. The results show that HF performs better than CWF in improving the flexural strength of materials, and the addition of CWF effectively enhances the toughness and splitting tensile strength of the material. The combination of the two can achieve a comprehensive strengthening effect. After 28 days of curing, the maximum increase in flexural strength of the composite specimens compared to the undoped specimens was 35.73%, and the maximum increase in splitting tensile strength was 20.88%, both of which were higher than those of the corresponding single doping group specimens. In addition, the performance of the composite group specimens in water resistance and acid resistance tests is better than that of the control group and the single addition group, indicating that the multi-scale fiber composite method helps to achieve a comprehensive improvement in material strength and weather resistance.
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Multi-physics Field Simulation Modeling and Analysis of Press-pack IGBT Devices Considering Submodule Characteristics Difference

LI Ying, MA Kai, TAN Lingqi, CHEN Siyu, XING Zhen, LI Hui, LAI Wei

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To address the issue of overlooking the non-uniform distribution of parameters among submodules in traditional multiphysics field modeling of PP-IGBT devices, a novel multiphysics field coupling model is proposed, which incorporates the stochastic distribution of pressure and conductivity among submodules. Firstly, a mathematical model for the pressure distribution of submodule groups and the conductivity distribution of chips using mathematical statistics methods tailored to PP-IGBT devices is established. Next, an electrical-thermal-mechanical multiphysical field coupling model for multi-chip PP-IGBT devices is constructed, validated through single-chip transient experiments. Lastly, a stochastic simulation method is introduced, based on the Monte Carlo method to address the variability in pressure and conductivity among chips. Besides, statistical analysis under conditions of uneven parameter distributions among submodule groups is conducted, elucidating the current and temperature distribution laws in such scenarios. Results show that the uneven pressure and conductivity of the single-chip submodule have a great impact on the distribution uniformity of the current and temperature, with a maximum increase in the unevenness of the electro-thermal distribution about 390% and 19%, respectively.
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Simulation and Influence Analysis of Heat Dissipation Performance of Reducer Casing for an Aviation Transmission System

ZHANG Qingcheng, SONG Chaosheng, LIU Hang, YUAN Dechen

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Taking the reducer casing of unmanned helicopter transmission system as the research object, the thermal-fluid-solid coupling calculation model is established. The flow field and temperature field in the reducer cabin is simulated based on Fluent. The effects of the airflow velocity and direction of the front air-inlet, the position of the side vent, and the number and position of the heat sink on the heat dissipation Performance of the casing are analysed. The results show that, with the increase of airflow velocity, the temperature distribution pattern of the casing wall is consistent, but the overall heat dissipation performance is enhanced; the airflow direction of the air inlet can directly change the flow field in the cabin, which significantly affects the temperature distribution of the outer wall of the casing; the position of the side vent can change the airflow distribution in the cabin, which indirectly affects the temperature field on the wall of the casing; and the the additional cooling fins on the casing surface can significantly reduce the temperature of the magazine wall and improve the thermal performance of the casing. The simulation results provide a basis for determining the percentage of heat dissipation in the casing, selecting the location of the heat sink, designing the of air-inlet, and arranging the side vent during the development stage of the gearbox.
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Research on multi-objective optimization of luffing mechanism of straight-arm aerial working platform

GONG Chao, HE Shanghong, YANG Geng, HUANG Yi

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Aiming at reducing the maximum thrust of the cylinder and improving the smoothness of the luffing action of the straight-arm aerial working platform, firstly, the working principle of the amplitude changing mechanism and the mathematical modeling of the cylinder thrust were analyzed, and the accuracy of the mathematical model was verified through tests, then, the design variables, constraints and objective function expressions of the optimization problem are determined on the basis. NSGA-Ⅱ( fast non-dominated sorting genetic algorithm) was used to solve the multi-objective optimization problem, and Pareto front optimal solution set was obtained. The comprehensive satisfaction function based on signal-to-noise ratio was used to evaluate the solution set, and the solution with the highest satisfaction was selected. Finally, by comparing the results before and after optimization, it can be seen that the optimal design based on the high-precision mathematical model reduces the maximum thrust of the luffing cylinder by 10.8%, the maximum displacement change rate of the cylinder for each 1° of luffing decreases by 28.4%, and the cylinder stroke goes down by 2.1%.
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Research on Safety Control Strategy of Hydropower Symbiosis Seawater Desalination System in Coastal Steel Plant

WU Liyun, Zheng Zhong, Chen Sujun, Yu Yuebo, Chen Delei, Zhang Kaitian

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Taking the hydropower symbiosis seawater desalination new technology system of a coastal steel enterprise as the subject, this paper addresses the challenges of using the steam turbine's exhaust steam as the heat source for low-temperature multi-effect evaporation seawater desalination within a system where the steam turbine generator set is closely coupled with the seawater desalination unit, presenting significant difficulties in joint safety control and a lack of technical solutions. From the perspective of prioritizing equipment safety, this paper designs safety control strategies suitable for the hydropower symbiosis process, including start logic, equipment safety interlocking protection logic under equipment failure conditions, and mode switching protection logic for the seawater desalination unit during low steam turbine load scenarios, enabling bidirectional interlocking protection for the steam turbine generator set and the seawater desalination unit. The practical application of this technical scheme at a certain coastal steel plant demonstrates that the designed hydropower symbiosis safety control strategies can achieve a safe and orderly start-up of the entire system. In the event of equipment failure, it can realize a bidirectional safe interlocking shutdown of the main equipment system, capable of stopping the seawater desalination unit in conjunction with the failure of the steam turbine generator set, and vice versa. Concurrently, the safety strategy can adapt to the needs of large load adjustments of the steel plant's gas supply, with significant effects on safe operation.
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Boiler Water Quality Prediciton Algorithm Based on SSA-LSTM

guoxiaocheng, chenyingrui, linrujuan, jianghaiyang, wangkai

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Predicting the water quality of industrial boilers is crucial for ensuring operational safety and efficiency. While Long Short-Term Memory (LSTM) neural networks excel at handling extensive temporal data, their parameter selection is not directly determined and often susceptible to local optima. Hence, optimizing these parameters becomes essential. This study aims to propose a water quality prediction algorithm by leveraging the Sparrow Search Algorithm (SSA) to optimize LSTM.By simulating sparrow foraging behavior, SSA iteratively refines LSTM parameters to seek more optimal configurations. The optimized LSTM algorithm is employed for processing water quality data, forming the core of the SSA-LSTM predictive model. Experimental findings reveal that compared to traditional LSTM and CNN-LSTM models, this algorithm demonstrates higher accuracy and reliability in forecasting industrial boiler water quality. Achieving an accuracy of 99.99%, with a Mean Absolute Error (MAE) of 0.001940 and Relative MAE (RMAE) of 0.002083, this research presents an effective method for water quality prediction in the industrial domain. It underscores the potential application value of SSA-LSTM in time series forecasting tasks within industrial settings.
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Vehicle Lane Change Risk Discrimination with Improved Intrusion Time Modeling

Qin Yaqin, ZHAO Yuan-Ling, XIE Jiming, GUO Miao, LIUYonghua, Chen Liang

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Considering the safety and comfort of vehicles during lane changing, a vehicle lane changing traffic conflict recognition model based on the improved PET algorithm and a lane changing behavior discrimination model based on an Eigen class (Eigen class) classifier are proposed. Firstly, micro-driving data are extracted from a publicly available dataset (City Sim) of urban expressway intersection area, and an improved Post - encroaching Time (PET) model is established to compute lane-changing features. Then, on the basis of correlation analysis, Eigen class classification method is used to identify the important characteristic variables of vehicle lane changing risk, and to construct a vehicle lane changing risk discrimination model with improved PET as the indicator. Finally, the accuracy of the lane-change risk discrimination model is evaluated by comparing and analyzing the classification prediction performance with that of K-nearest neighbor classification (KNN) and multiple support vector machine (MSV) algorithms. The results show that the discrimination accuracy of the lane change risk discrimination model is 99.73%, which is better than the KNN algorithm (99.71%), MSVM algorithm (99.50%) and DT algorithm (99.61%).
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RFID Authentication Scheme for Electric Internet of Things

Chenmengmeng, Lundi, Limingyan

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With the rapid development of electric Internet of Things technology, it is of great significance to build energy Internet. The identification and authentication of power IoT terminal equipment is the basis for ensuring the safe and stable operation of energy Internet. In order to realize efficient collection and security authentication of massive power terminal equipment information, this paper proposes an RFID authentication protocol for power Internet of Things, the protocol uses RFID technology and is designed based on national secret SM3 and SM4 algorithms, which not only realizes the mutual authentication between the reader and the power equipment, but also ensures the transmission security of the power communication data, and reduces the computational complexity of equipment tags. Security analysis shows that the protocol satisfies security requirements, such as untraceability, withstand replay attack, de-synchronization attack and denial of service attack, etc. BAN logic analysis further shows the protocol satisfies the mutual authentication, Performance analysis shows that the protocol has better performance advantages in tag computation, storage, traffic and database search efficiency.
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Vehicle Constrained Path Planning Algorithm with Optimized Cost Function

Xie Peng, Ou YangQi, Zhang Xinglan, Li MeiQi, Huang BiYuan

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Aiming at the problems of unsolved mobile robot path planning in multi-obstacle scenarios, large change of steering speed state and too close distance between path and obstacles, a vehicle constrained path planning algorithm based on the improvement of cost function is proposed. The method takes the vehicle constrained path planning algorithm Hybrid A* as the base algorithm and its cost function as the original cost function. A dual start and dual end search process is established to form a two-way search and reduce the path search time. Introduce steering constraints to reduce the steering speed state change of the traditional Hybrid A* algorithm. Introduce distance constraints to reduce the priority of dangerous edge nodes. The experiments demonstrate that compared to the traditional vehicle constraint Hybrid A* algorithm, the improved Hybrid A* algorithm reduces the average path search time by 12.043%, the steering speed state change by 16.623%, and the priority of nodes close to the danger edge by 25%. This series of experimental results successfully improves the traditional Hybrid A* algorithm in planning path algorithm and provides an effective solution for mobile robot path planning in multi-obstacle scenarios..
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Lightweight Micro-expression Recognition Method Based on Sparse Inverse Covariance Estimation

Yao Chong, Zhang Hanwen, Lv Yaodong, Wei Xingyu, Wu Lingling

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In complex military confrontation environments, where unmanned aerial vehicles (UAVs) conduct automatic reconnaissance and identification of multi-class ground targets using multi-scene remote sensing images, targets often exhibit characteristics such as color similarity with the background, blurred boundaries, and variable background environments. Traditional convolutional networks struggle with low accuracy and robustness in multi-class segmentation of multi-scene remote sensing images under these conditions. To address this issue, we propose a novel multi-scene remote sensing image segmentation algorithm. This algorithm integrates the Residual Cross-layer Multi-scale Channel and Spatial Attention Module (Rs-CMACM) and the Path Aggregation Network (FAN) to enhance key features, suppress irrelevant information, and improve the delineation of target boundaries. Additionally, dynamic data augmentation and an Image Restoration Sub-network (IRSN) are introduced to enhance segmentation accuracy in complex backgrounds. Firstly, Rs-CMACM and FAN are cross-layer integrated into the backbone network of a typical object segmentation network, enhancing the model"s feature extraction capabilities and fusing multi-scale features at different depths, thereby reducing segmentation bias caused by noisy backgrounds. Secondly, the incorporation of dynamic data augmentation and IRSN compels the model to focus on the intrinsic characteristics of images, enabling the extraction of more robust feature representations under various environmental conditions. These improvements significantly enhance the accuracy and robustness of the model in multi-class segmentation tasks for multi-scene remote sensing images, thereby increasing the precision of target segmentation.
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Lightweight design of orthodontic dental casts

ZHANG Yong, LI Xuyan, LI Mengya, LIU Fei

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Orthodontic dental casts lightweight research was very important to reduce the cost of invisible orthodontics. Actual dental casts deformation was analyzed by finite element method, which were successively filled by hollow, honeycomb, and cube structures. Film lamination was equivalent to the outer surface normal load of orthodontic dental casts, whose overall deformation was measured to evaluate lightweight design. At last the new dental cast was used to verify the research results. The results indicate that honeycomb structure is best for orthodontic dental casts lightweight design, which is followed by cubic and hollow structure successively.
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Effect of Rural-urban Binary Structure on the Spatial Distribution and Sources of Heavy Metals in the Sediments of a Typical Mountainous River

wangchao, licheng, jiaboyang, jiaoyang, chenyanlin, panchengyong, panyujie

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The spatial distribution of heavy metals in the sediments of mountainous rivers is influenced by population density and industry type. In December 2019, sediment samples were collected in a typical mountainous river (Taohuaxi River) which covered both urban and rural sections in Changshou District, Chongqing. The contents of heavy metals in the sediment samples at each point were measured. The results showed that the average heavy metal contents in the sediments of the urban section of Taohuaxi River were higher than those in the rural section for all the eight heavy metals monitored, with significant differences observed in Cd and Cu contents. Human population density was found to affect the spatial distribution of heavy metals in river sediments. A proportion of 20.59% in the monitored sites in the basin was found to be Near Moderate or Moderate Pollution according to the improved Geoaccumulation Index (I_m), indicating that heavy metals were only enriched at certain sites in Taohuaxi River. According to the Potential Ecological Risk Index (RI), 67.65% in the monitored sites in the basin were at Medium or High potential ecological risk. In the Sediment Quality Guideline method (SQGs), the toxicity of heavy metals in the sediments at all monitoring points was found to be of moderate risk to organisms. The ecological risks of heavy metals in the sediments of Taohuaxi River should not be ignored. The results of the Positive Matrix Factorization (PMF) model analysis showed that five main sources of heavy metals in the sediments of Taohuaxi River were identified. The contribution of these sources was in the order of aquaculture sources (38.79%) > natural sources (20.40%) > anthropogenic mixed sources (20.35%) > industrial sources Type II (16.69%) > industrial sources Type I (3.78%).
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Comparative analysis of coal spontaneous combustion tendency prediction based on machine learning: evaluation of coal spontaneous combustion temperature and spontaneous ignition period

ZOU PEI ZHE, YE YU XIN, Liang xiao yu, han chao

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In order to develop a high-performance model for predicting the spontaneous combustion tendency of coal, this study utilizes multi-indicator gas and industrial analysis parameters of coal. It employs random forest, neural network, support vector machine, and Stacking stacking methods to predict the spontaneous combustion temperature and natural ignition period of coal in order to evaluate its spontaneous combustion tendency. The findings indicate that the Stacking stacking method-based prediction model exhibits superior generalization ability. Furthermore, feature importance analysis reveals that volatile matter and ethylene demonstrate strong correlations with predicting the natural ignition period and spontaneous combustion temperature of coal respectively. Analysis of model performance indicators suggests that increasing data volume significantly enhances the generalization performance of random forest, neural network, support vector machine, and Stacking stacking methods in predicting coal spontaneous combustion temperature. However, simply increasing data volume has limited impact on improving the prediction model for coal's natural ignition period; instead, exploring new features is essential for enhancing model performance. This study offers valuable insights into predicting coal spontaneous combustion tendency and optimizing predictive models.
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Weakly supervised temporal action localization method based on modal bias compensation

CHEN Zhongming, LI Ziqiang, GE Yongxin

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Weakly supervised temporal action localization has become one of the research hotspots in the field of video understanding due to its application potential in intelligent monitoring, video retrieval and other fields, and its low cost of training data annotation. In response to the poor localization performance caused by existing multimodal learning-based localization methods ignoring the biases inherent in each modality, we constructed an RGB action subject information compensation module and designed a optical flow-based dominant influence suppression strategy aimed at eliminating the location bias caused by each modality on the training model. Experimental results on two benchmark datasets THUMOS14 and ActivityNet v1.2 show that under multi-scale temporal intersection over union, mean average precision reached 45.3% and 26.5% respectively, overall localization performance is better than some latest methods, which demonstrates effectiveness of our proposed method. This method improves the basic localization performance of temporal action location models by compensating for bias at a coarse-grained modal level. It is also compatible with fine-grained viewpoint localization methods.
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Effect of built-in finned Trombe Wall on the Thermal Environment of Heating Room in Cold region

Qi Xiaobing, Wang Jialong, Wang Ye

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In order to study the contribution rate of built-in fin-type Trombe wall to reducing indoor heating energy consumption, taking ordinary residential houses in Lanzhou as the research object, fins are arranged on the heat absorption surface of Trombe wall to enhance heat transfer, so as to achieve the purpose of improving indoor thermal environment. The results show that the isosceles right-angled triangular fins with a height of 20 mm, a transverse spacing of 0.20 m, a longitudinal spacing of 0.533 m, and an in-line arrangement have the best improvement effect on the heat transfer performance of the Trombe wall and the thermal environment of the room. During the entire simulation period, the fin-type Trombe wall heat absorbing surface (Nu) ? is up to 21.28 higher than the finless Trombe wall heat absorbing surface (Nu) ?. Compared with the ordinary room, the energy saving rate of the finless Trombe wall room and the fin-type Trombe wall room is 36.38 % and 44.63 % respectively, that is, the energy saving rate of the fin-type Trombe wall room is 8.25 % higher than that of the finless Trombe wall room. This study has important theoretical reference value for promoting the process of clean energy utilization in solar-rich areas.
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Structural Characteristics and Dynamic Performance Analysis of A New Type of Floating Flexible Ring Gear

hushengyang

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Due to the influence of deformation, the load distribution of planetary transmission system is not uniform, and the wave shock is frequent, which is prone to unbalance loading and stress concentration, and the extreme condition of alternating heavy load and strong impact become more and more prominent. The existing methods to improve the performance and prolong the life of planetary systems have little effect on the harsh conditions of alternating heavy loads. In this paper, the floating flexible ring gear is proposed based on the foreign key-type ring gear, which is composed of inside ring and outside ring, the ring gear is a thin-walled structure, and the circumferentially restricted motion and radial slip are realized between the inner ring and outer ring through a convex key, and the clearance is used to realize floating adjustment and overload protection. The strong flexibility of inner ring can realize the unbalance loading of system each branch and absorb kinetic energy to improve the dynamic load. The analysis shows that floating flexible ring gear has improved the load sharing and dynamic load performance significantly compared with the full fixed ring gear and L-shaped ring gear, which can provide theoretical guidance for the ring gear design of planetary transmission system.
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Knowledge graph enhanced multi-task graph convolution recommendation method

Wang Kelun, Li Xiuqing, Jiang Huaiyan, Liu Yu

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The issue of information explosion and information cocoon is becoming increasingly serious, and users need accurate and personalized recommendation methods to enhance their experience. Traditional recommendation methods based on collaborative filtering often face data sparsity problems in actual application scenarios and have difficulty meeting personalized recommendation needs. Inorder to solve the above problems and adapt to the development of modern recommendation tasks, a Knowledge Graph enhanced Multi-task Graph Convolution Recommendation Method (KGCR) is proposed. This method integrates the relationship structure and node attributes in the knowledge graph, learns the potential associations between projects and entities through the knowledge graph embedding module, and applies the Neural Matrix Factorization architecture to design the recommendation module to learn the interaction function between users and items. Finally, the feature transfer mechanism shares feature learning between the two modules. Experimental results in five real recommendation scenarios show that the accuracy of this recommendation method exceeds multiple advanced benchmark models, with an average increase of 6.3%, demonstrating excellent recommendation performance and generalization ability, and helping to solve the problem of data sparsity.
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Study on bearing capacity performance of of reinforced steel fiber concrete structure based on the cohesive zone model

Huang Yiqun, Meng dong-dong, Lin Benqing

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To investigate the mechanical response and fracture mechanism of the steel fiber reinforced concrete (SFRC) structure, a numerical modeling method based on the application of cohesive elements was proposed. In the proposed model, cohesive elements were used to characterize the potential fracture surfaces and the rebar-concrete interfaces. By considering the mixed-mode damage relation, friction, and the bridging effect of fibers, a constitutive model of SFRC potential fracture surfaces was developed. Besides, based on the traditional bond-slip relation, a modified constitutive model of the rebar-concrete interface was proposed by considering the separation in the normal direction. To validate the proposed model, a group of SFRC four-point bending experiments was carried out. Through the comparison between the simulation and experiments, the proposed model was proved to be able to simulate the mechanical response and the fracture behavior of the SFRC structure appropriately. According to the characterization of the SFRC constitutive model, the influence of the fiber content and concrete friction factor on the structure bearing capacity was studied. It is found that when the fiber content is small or the friction factor is unreasonable, the bearing capacity and the ductility would decrease significantly.
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Caving structure and crack evolution law of overlying rock in gob-side roadway retaining face of flexible formwork concrete wall

shizhanshan, fanyongjun, ligang, chiguoming, liuhang

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In order to study the difference of the roof caving structure and crack evolution between gob-side entry retaining and traditional coal pillar mining. Taking the 52605 and 52606 working faces of Daliuta Coal Mine as the engineering background.Through two groups of simulation experiments of similar materials. The mining process under two working conditions was simulated, recorded the process of overlying rock movement and fracture evolution. Research shows that, the crack rate formed at the end of primary mining is less than that of secondary mining when using gob-side entery retaining with flexible formwork concrete wall. But, after traditional coal pillar mining, the formation and evolution law of overlying rock fissures on both sides of coal pillar is similar. There are differences in crack rate, crack type, caving range and caving angle between the two coal mining methods. The crack rate of the overlying rock in the gob-side roadway retaining face of flexible formwork concrete wall is 5.0756%, the collapse range is within 50m, and the collapse inclination angle is in the range of 31°and86.9°. The crack rate of the overlying rock in the leaving coal pillar mining face is 2.8604%, the collapse range is within 40 m, and the collapse dip angle is between 50°and 52°, mainly the shear cracks developed along the caving dip angle. After the end of mining concrete wall in the face of gob-side entry retaining , the rock layer on both sides of the roof of the concrete wall does not slip, forming a hinged structure. On the other hand, after the mining is completed. the overlying rock layers on both sides of the coal pillar in the staying coal pillar mining face are cut off as a whole. The overlying strata form obvious structural differences on both sides of the concrete wall and coal pillar, which forms a significant concentrated stress effect on the load distribution of the concrete wall in the gob-side roadway retaining face.
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Bearing Characteristics of Plum-Blossom Pile under Lateral Loads in Sand

DENG Yousheng, LI Long, ZHAO Huiling, ZHANG Keqing

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Plum-blossom pile is a novel kind of new cross-sectional shaped pile, and at present, there is no relevant research on the bearing characteristics of plum-blossom pile under lateral load. Based on the theory of circular hole expansion, the calculation method of soil displacement around plum-blossom pile in sand during pile sinking is established. Considering the special-shaped effect of plum-blossom pile section, the soil squeezing displacement in the positive direction of coordinate axis is obtained by using the principle of coordinate transformation and superposition on the basis of Hooke"s law. The differential equation of pile deflection curve is derived by using m method and its difference solution, and the reliability of the established theoretical method is verified by comparing with the experimental results. The results show that the horizontal displacement of soil between plum-blossom pile and circular pile with equal cross-section is similar. With the increase of horizontal load, the horizontal displacement first increases and then decreases, and the horizontal displacement of soil near plum-blossom pile is about 73.5% of that of circular pile with equal cross-section. The vertical squeezing force of plum-blossom pile on the soil facing surface under horizontal load is small, and the vertical displacement fluctuates with the increase of horizontal load. With the increase of horizontal load, the horizontal displacement of soil in the middle of plum-blossom pile first increases and then decreases, and the maximum horizontal displacement is about 75% of that of circular pile with equal cross section.
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Global path planning method for intelligent vehicle based on virtual flow field

JI Jie, PAN Deng, LIU Jian, ZHAO L就能, ZHANG Bohan

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According to the characteristic that fluid can naturally explore reasonable flow direction and feasible path in complex environment, a global path planning method for autonomous driving based on virtual flow field is proposed. Firstly, a mathematical model of virtual road flow field is established based on the theory of fluid dynamics, and the computational fluid dynamics method is adopted to numerically solve the state of flow field, so as to generate multiple streamlines from the starting point to the destination in a large-scale complex road network. Meanwhile, by constructing a comprehensive evaluation function of the planned path, the optimal global path is selected from multiple streamlines. Finally, a combined GNSS/INS positioning system is designed to collect real data of road network and build a global static road map, and the proposed method is experimentally verified in a campus scenario. The experimental results show that the global path planning method based on virtual flow field can plan and select a complete and smooth global optimal path according to the automatic driving task and avoid the non-solution situation that falls into the local minimum of the environment.
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Integrated scheduling of green job shop considering AGVs charging

Li Zhengfeng, Gu Wenpeng, Zhang Guohui, Zhou Gaofeng

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Automatic guided vehicle (AGV) has become an important transportation tool in job shop, which brings new problems for job shop scheduling, such as AGV assigned, AGV power constraint, AGV quantity constraint and so on. Aiming to green scheduling problem of job shop considering AGVs charging, the multi-objective job shop scheduling optimization model with makespan and energy consumption was established considering the AGV power and AGV charging, and the improved genetic algorithm is devised to solve this model. In the algorithm, the two-segment chromosome coding of equal length job assignment and AGV allocation was using, the local search strategy and corresponding GA operators for job and AGV code segment were adopted, the decoding mechanism considering AGV power and charging constraints was designed. Finally, through the orthogonal experimental simulation of ft06 case using the method of range and variance, the influence of AGV quantity and AGV power on the optimization was analyzed. The model and algorithm were verified by simulation.
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Complementary fusion RGB-D food image segmentation based on attention mechanism

ZHENG Yi, LIU Yu, HU Kai, LI Baihua

Abstract: (180) HTML (0) PDF (0.00 ByteKB) (0)

Food image segmentation plays an important role in the field of food volume estimation, but there is still much room for improvement in its performance due to the fine structure of food and some challenges in shooting, such as blurred boundaries and image overexposure. To solve these above problems, a complementary fusion RGB-D Food Image segmentation Network (RGB-D ABCFNet) based on attention mechanism is proposed. The network adopts U-shaped structure and is divided into encoding process and decoding process. In the coding process, the Expand Head Channel Attention Module (EHCAM) proposed extracts the channel features that are more helpful to segmentation of the depth map, so that the characteristics of depth map are well complemented to RGB feature map by adding layer by layer. In decoding process, the Multi-Head Spatial Attention Module (MHSAM) present enables the detailed information and location information to be well recovered, and the extracted semantic features can better map the semantic segmentation results. In addition, a multi-class food semantic segmentation dataset Nutrition-Pix is constructed and a large number of comparison and ablation experiments are conducted on it, proving that the proposed model is superior to the current method with the mIoU of 87.5%.
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Two-stage Real-time Scheduling Algorithm for Complex Robot Manufacturing Cell

LiXiaohui, JiNingbo, DongYuan, ZhaoYi, JinYinli

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In response to the real-time scheduling problem in complex robot manufacturing cell with multiple constraints such as multiple handling robots, multiple line transfers, and buffer capacity limitations, a new two-stage real-time scheduling algorithm is proposed with the objective of minimizing the maximum completion time. The algorithm comprises an initial solution construction phase and a local search optimization phase. In the first phase, a Multi-Layer Feedback Queue (MLFQ) scheduling algorithm based on priority rules is designed by integrating the ideas of first-come-first-serve and round-robin approaches to quickly generate high-quality initial solutions. In the second phase, a simulated annealing algorithm based on reinforcement learning (Q-learning) is designed to perform local search on the initial solutions. The local search utilizes 7 neighborhood search operations and selects the best operation based on the Q-table values of the current state in the Q-learning algorithm to generate new solutions. Experimental comparisons on modified and augmented standard datasets validate the effectiveness and stability of the algorithm through improvements in optimal values, average values, and variance values.
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The distribution characteristics of near-shore wind parameters considering wind-wave coupling

XIE Ze-en, LI Jia-yu, LI Jia-wu, CAI Song

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To study the distribution characteristics of wind parameters near the shore, a two-dimensional geometric model is established based on CFD (computational fluid dynamics) technology. Because of the two-dimensional wind action on a calm water surface, the SST k-ω turbulence model and multiphase flow model are adopted to numerically simulate the distribution characteristics of wind parameters. The changes in development distance, water depth, incoming wind speed, and slope of underwater terrain on the distribution characteristics of wind parameters are analyzed. The results show that when the development distance is less than 60m, the wind speed near the water surface is larger than the inlet wind speed, showing an accelerating phenomenon. When the wind speed exceeds 60m, the wind speed increases with the increase of the position height, and the speed remains unchanged after reaching a certain height. The variation of slope does not affect the distribution characteristics of wind parameters. Water depth has a strong correlation with wind parameter characteristics. The increase in water depth will lead to a nonlinear increase in gradient wind height and has a great influence on wind speed. The inlet wind speed does not affect the gradient wind height and wind structure but will affect the acceleration effect near the inlet. The change of wind attack Angle has a strong correlation with inlet wind speed and water depth. With the increase of wind speed, the change of wind attack Angle is more obvious. Generally, when the wind speed increases, the wind attack Angle will change greatly.
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Influence of threshold drift on short circuit characteristics of silicon carbide MOSFET

Tang Lei, Wang HaiBing, Jiang Huaping, Yu Zhixin, Zhong Xiaohan, Liu Dingjie

Abstract: (398) HTML (0) PDF (0.00 ByteKB) (0)

The short-circuit durability of metal oxide semiconductor field-effect transistors (MOSFETs) has attracted much attention from various fields. The dynamic threshold drift problem of silicon carbide MOSFETs may cause changes in their short-circuit capability. A silicon carbide MOSFET short circuit testing platform was built to address this issue, and the changes in Class I short circuits of silicon carbide MOSFETs under different threshold voltage differences were studied. The article provides a detailed analysis of the working principle and short-circuit test results of the testing circuit. The experimental results show that the larger the threshold voltage, the greater the conduction resistance of silicon carbide MOSFETs, resulting in a larger short-circuit current and energy of silicon carbide MOSFETs.
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Algorithm design for Safety Control Terminal in Space-based TT＆C system

LI Zhaofei

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The traditional acquisition synchronization algorithm for spread spectrum security terminal had some shortcomings. This approach prolonged the security control processing time and failed to meet real-time requirements. The development of a high reliability and fast response synchronization algorithm is a key technology for the space-based TT&C receiver. To address this, a two-dimensional acquisition algorithm is employed, which is based on partial matched filtering assisted by inertial navigation + satellite navigation information and piecewise average FFT spectrum estimation. This conversion effectively reduces the Doppler frequency offset range and shortens the acquisition time. Additionally, the piecewise averaging FFT spectrum estimation decreases the variance of power spectrum estimation. Furthermore, a second-order frequency-locked loop assisted by a third-order phase-locked loop is used in the carrier tracking loop to achieve high maneuverability and wide range tracking. An anti-false lock decision mechanism has been added to both the carrier tracking loop and pseudo code tracking loop to quickly escape from false lock states. Engineering applications have demonstrated that the use of this proposed algorithm results in a safety control processing delay of no more than 500 ms for the spread spectrum safety control terminal, thus meeting the real-time requirements.
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Detection of Mask Wearing Status in Complex Kitchen Environments

FENG Yan, ZHONG Mingen, TAN Jiawei, YUAN Bingan, FAN Kang, ZHAN Zehui

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The basic requirement for catering staff to wear masks is widely acknowledged, but it still has not paid sufficient attention to mask wearing specification. To deal with this, a detection method for mask wearing specification was proposed for complex working environments of kitchen such as oil fumes, water vapor, and flames. Firstly, a targeted dataset named CKEMFD-12k was collected and constructed. Secondly, a multi-task convolutional neural network(MMWN) was constructed to extract key element information for assessing mask wearing status. By utilizing the self-designed multi-scale hybrid spatial pyramid pool module(MHSPP) and tube-embedded transformer attention mechanism(TETAM), the method achieved the highest average target detection accuracy of 94.68%, the minimum mouth-nose key points mean error of 4.62%, and the optimal mask region segmentation pixel accuracy of 94.32% compared to the existing network. At last, a algorithm was designed to calculate mouth-nose key triangle area and analyze their coverage relationship with the mask area, which provides a judgment method or three mask wearing status: normative wearing, improper wearing, and no wearing. Experiment shows that the comprehensive judgment accuracy is 93.57%, surpassing existing mainstream algorithms.
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Approximate Cycle Mining Algorithm for Large Graphs

JIANG Tao, LIU Xiaoting, XU Shangqin, GAO Shule, WANG Jian

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Cycle mining can help people deeply understand the structure and function of complex networks, which is of great significance for practical application fields such as road traffic networks, bioprotein networks, financial and economic networks, etc. However, the massive data in the information age makes cycle mining extremely challenging. In response to the problem of large data volumes but relatively limited available data that cannot mine complete cycles, the concept of approximate cycle (AC) is defined, and the approximate cycle detection algorithm (ACD) and its optimization algorithm (IACD) are proposed. Both algorithms are divided into three stages: first, calculate hotpoints through vertex degree calculation; secondly, perform forward and backward searches on the dataset based on hotpoints to obtain hotpoints and their neighbors, and use this to construct an index (H-Index); finally, calculate the tightness coefficient and average tightness coefficient between different vertices based on H-Index, the path between vertex pairs with a tightness coefficient greater than the average tightness coefficient is an approximate cycle. The IACD algorithm has been optimized in two aspects based on the ACD algorithm. On the one hand, it increases the deduplication of vertices in the acquisition of hotpoints and their neighbors, while reducing the number of searches for data. On the other hand, it uses function vectorization instead of cyclic modification in the construction of indexes. The experimental data used are all real datasets of SNAP public website. The experimental results show that both algorithms can run smoothly on larger datasets and have good scalability and efficiency. The efficiency of the IACD algorithm is about 25% higher than that of the ACD algorithm.
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Modeling and Optimization Design of Post-buckling Tensegrity Metamaterial

ZHANG Zexuan, ZHANG Liang, Ge Yipeng, ZHANG Jun

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Balancing the attainment of low-frequency bandgap with achieving higher load capacity is a significant concern in metamaterial design. By harnessing the post-buckling characteristics of bars, a novel tensegrity metamaterial is proposed, where the introduction of post-buckling leads to a softening of the structure"s stiffness, thereby enabling a low-frequency vibration isolation functionality with enhanced load-bearing capability. Utilizing the elliptic integral method to compute the post-buckling deformations of bars allows for the rapid determination of the stiffness of the tensegrity unit. Combined with the spring-mass diatomic chain model, bandgaps are calculated using Bloch"s theorem under periodic boundary conditions. To strike a balance between band gaps and load capacity, a data-driven dual-objective optimization method is employed, yielding the Pareto frontier of the post-buckling tensegrity metamaterial"s ultimate load and lower bandgap limit. Optimization results demonstrate that the bandgap frequency of the optimized structure can be as low as 3Hz, with a load capacity exceeding 100N. Compared to other low-frequency vibration isolation metamaterials, the ultimate load capacity can be increased by over 3.6 times at the same bandgap frequency.
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A finite volume-based phase field method for two-phase ferrofluid flows

ZHANG Shaosong, ZHANG Liangqi, CHENG Liming, WANG Xiaoshuang, XIAO Yao, ZENG Zhong

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In this paper, a finite volume method based on the WENO scheme is used to develop a two-phase flow phase field method including ferrofluids. The governing equations include the Navier-Stokes equations for incompressible flow, the Cahn-Hilliard equation for interfacial dynamics, and the Maxwell equation for the distribution of the external magnetic field. To overcome the challenges posed by the fourth-order nonlinear diffusion terms, we decompose the Cahn-Hilliard equation into two Helmholtz equations. The fifth-order WENO scheme is employed to handle the convection term of the governing equation, aiming to enhance accuracy and prevent numerical oscillations. The Zalesak"s disk problem shows that the proposed method has a higher phase interface capture accuracy compared to references, and is comparable to the high-precision phase field method. The proposed method is applied to the droplet shear deformation problem, and it is observed that the current method can capture more satellite droplets. Additionally, it is noted that the magnetic interfacial force favors droplet deformation when the direction of the external magnetic field aligns closely with the direction of droplet hydrodynamic deformation. Furthermore, an increase in the magnetic field intensity leads to droplet splitting. On the contrary, when the magnetic field is nearly perpendicular to the direction of droplet hydrodynamic deformation, a lower intensity magnetic field alters the direction of droplet deformation, while a higher intensity magnetic field directly deforms the droplet along the direction of the magnetic field.
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Analysis of physical and mechanical properties and influencing factors of aeolian sand in inland sandy river basin

JIA Wei, ZHANG Lingkai, DING Xusheng

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A large amount of aeolian sand is distributed along the main stream of the Tarim River. Due to the scouring effect of seasonal floods, sliding damage occurs on the river bank. In order to further explore its failure mechanism, the indoor direct shear, compression and penetration tests were carried out to explore the variation law of mechanical properties of aeolian sand under different water content and different dry density conditions. The results show that: (1) Direct shear test: with the increase of water content, the cohesion increases first and then decreases, reaching the peak at the optimal water content. The change curve can be expressed by quadratic function, and the internal friction angle decreases linearly. With the increase of water content, a viscous water film is formed on the surface of the particles. After reaching the optimal water content, the viscosity of the water film is weakened, resulting in a trend of increasing first and then decreasing. The thickening of the water film leads to a decrease in the sliding friction force when the particles roll. With the increase of dry density, the cohesion and internal friction angle increase linearly. With the increase of dry density, the particle spacing decreases, the van der Waals force increases, and the cohesion increases. At the same time, the contact occlusion ability between particles is enhanced, and the internal friction angle is increased. (2) Compression test: With the increase of water content, the compression coefficient and modulus of resilience showed a linear increasing trend. Under the same axial stress, as the water content increases, the water film becomes thicker, the resistance between the particles becomes smaller when the dislocation displacement occurs, the compressibility increases, and the rebound amount increases. With the increase of dry density, the compression coefficient decreases linearly and the rebound modulus increases linearly. With the increase of dry density, the contact between particles is close, the resistance between particles increases when the dislocation displacement occurs, the elastic deformation of the soil contact point increases, the compression deformation decreases, and the rebound amount increases. (3) Permeability test : With the increase of dry density, the permeability coefficient decreases linearly, distributed between 1×10-4cm / s and 3×10^-4cm / s, which is 2 to 3 orders of magnitude different from the theoretical value obtained by experience. The traditional theoretical permeability coefficient calculation formula is modified. After eliminating the error caused by the low dry density, the measured value obtained by the test is close to the calculated empirical value, and the whole can be expressed by a linear function. As the dry density increases, the resistance of water molecules passing through the pores between soil particles becomes larger, resulting in a decrease in permeability. The research results can provide reference for the management and maintenance of the Tarim River bank..
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Optimization Design Method for Powertrain of Electric Construction Machinery Considering Manufacturing Cost

HUANG Qi, HUANG Xiaohui, CAO Huajun, ZENG Hao, YAN Wanbin

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In order to improving operation performance of electric construction machinery and accelerate the dev elopment of electrification of construction machinery and reduce carbon emissions from the Non-road mobile machinery. An optimization design method for powertrain of electric construction machinery considering manufacturing cost was proposed. firstly, the pure electric wheel loader was selected as the object, and the fuzzy TOPSIS was used to select the appropriate optimization components. Then the operating costs under customer demand conditions, the power performance considering loader turnaround conditions, and narrowly defined manufacturing costs were optimized with the help of an improved multi-objective jellyfish search algorithm. Finally, the result was analyzed and verified by platform based on MATLAB/Simulink. And showed that the improved algorithm is superior than others; The working efficiency of the motor increased by 0.214%, 0.190%, 0.150% in different condition; the acceleration time from 0 to maximum speed decreased by1.798s, 2.231s, 1.006s；Manufacturing cost decreased by 3.129%, 5.043%, 3.946%.the power performance and comfortability were improved.
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Dietary Recommendation System Based on Adaptive Multi-nutrient Goals

Yan Xingyu, Wang Han, Qi Yumei, JIANG HUAIYAN, Liu Yu

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In order to make healthy and personalized diets conveniently, a dietary recommendation system for Chinese cuisine is proposed. Firstly, the ResNet-18 neural network model that can classify three meals was trained through the self-built database, and the three-meal confidence of 2167 Chinese dishes was obtained as the basis for recommendation. Then, the optimization model was constructed, where the information of nutrients, ingredients and categories of dishes were abstracted as decision variables, and the objectives of nutrition and eating habits were set as constraints. The optimal solution of the recommended dishes and their grams was calculated by using the adaptive Gurobi optimizer. Experiments show that the system can achieve the set goals at three levels: at the nutrient level, it can meet the intake targets of 19 nutrients for healthy users or 30 chronic patients; At the level of food ingredients, it can ensure the food diversity, complete the selection of favorite dishes and the avoidance of taboo ingredients; At the dish level, it can realize the function of pairing dishes and recommending three meals respectively.
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Performance of Copper Slag based Ferrous Oxalate Cement after Exposure to Elevated Temperatures

TIAN Xincong, HE Huan, ZHOU Xintao, LUO Zhongqiu, DU Xin

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Copper slag based ferrous oxalate cement (CS-FOC) has great potential application prospects in the fields of repairment of highStemperature kilns and stabilization/solidification of nuclear wastes due to its properties such as fast-setting and high early age strength. In this study, the evolution of properties, phase compositions and structure of CS-FOC after exposure to elevated temperatures was comprehensively researched on the basis of our preliminary studies. The results showed that the compressive strength can reach 55.1 MPa when naturally cured for 28 days, and it was mainly composed of new-formed ferrous oxalate dihydrate (FeC2O4.2H2O) and unreacted fayalite (Fe2SiO4). The compressive strength and structure of CS-FOC changed regularly after exposure to elevated temperatures. When treated at higher than 250 ℃, the formed FeC2O4.2H2O started to decompose into iron oxide, and the strength decreased because of the destroyed structure. The strength can stably keep at about 15 MPa after exposure to the temperature of 1000 ℃. Thus, CS-FOC has better thermal stability than ordinary Portland cement and remains at higher level compressive strength.
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A Method for Constructing a High-Accuracy Prediction Model for Zirconium Alloy Fatigue Life Based on the Three-Parameter Weibull Distribution

Hu Shuwei, Qi Tongbaihui, Guo Shan, Qiu Xi, Yin Hongbu, Lan Xun, Gao Shixin, Xin Yong

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During the operation of nuclear reactors, zirconium alloy claddings are subjected to significant cyclic stresses, necessitating a comprehensive assessment of the material’s fatigue properties to prevent structural failure. This study focuses on enhancing the accuracy of predictive models for the fatigue performance of zirconium alloys by employing fatigue test data from alloys in two distinct heat-treated states. A three-parameter Weibull distribution model, formulated using the probabilistic weighted moments method, was developed to construct Reliability-Stress-Number of cycles (R-S-N) curves. These curves were rigorously compared and validated against the R-S-N curves obtained using the traditional Basquin model. The findings indicate that the S-N curves, derived from the three-parameter Weibull distribution, demonstrate superior fitting accuracy and markedly surpass the performance of those obtained through conventional methodologies. This advanced modeling approach thus proves to be highly effective and applicable for the detailed analysis and prediction of fatigue properties in zirconium alloys, offering significant implications for the design and safety of nuclear reactors.
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A closed-form solution to an elliptic cylindrical thermal inclusion in a bi-material under plane strain

Liu Jun, Feodor M. Borodich, Lyu Ding, Jin Xiaoqing

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This article focuses on the analysis and solution of the plane strain problem of bi-material containing an elliptical cylindrical thermal inclusion. Following the inclusion analysis method proposed by Eshelby, we derive closed-form analytical solutions for the elastic field induced by an elliptical thermal inclusion. Inspired by Dundurs' parameters, we introduce a new material parameter (ranging from -1 to 1) and five tensorial structured expressions to succinctly represent the current analytical solution, facilitating practical applications. For typical circular inclusion problems, our analytical solution can be greatly simplified, and we derive jump conditions for displacement, strain, and stress at the bonded interface of the bi-material. By adjusting Young's moduli and Poisson's ratios of the bi-material, the current solutions can degenerate into analytical solutions for a full or half-plane containing a thermal elliptical inclusion. The consistency of these solutions with previously published analytical solutions for specific cases, along with the numerical solutions presented in this article matching those in the literature, confirms the correctness of the derived analytical solutions in this study.
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Arbitrary polygonal hybrid stress element considering creep

Lizijun, TianJingjie, HuChanghao, TanDawen, XiaFan, HouChunyao, LiuLuyao, NingShaoqing, Guo Ran

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The post-construction settlement of roadbed is directly related to the safety performance of highway. The prediction of creep behavior is of great significance to ensure the long-term safety of roadbed engineering. In finite element numerical simulation of creep behavior, the meshing of complex structural models requires a large amount of computational resources, as well as a large amount of computational time. In this paper, a new arbitrary polygonal hybrid stress element (PHSEM) considering creep is proposed for roadbed settlement problems in engineering. Based on the hybrid stress element method and the creep behavior of roadbed soil, the basic element format of PHSEM is derived. The analysis shows that this element introduces a higher-order stress field, which can better improve the calculation accuracy. The numerical calculation model of roadbed creep is further established, and the comparative analysis is carried out with MARC. The study shows that: the numerical simulation curves of PHSEM are well fitted, and the deviation is within a reasonable range, which verifies the validity of arbitrary polygonal stress hybrid element considering creep; the element can be a polygon with variable number of edges when meshing, which can well simulate the roadbed model with multiple media and realistically calculate the stress distribution in different parts; the establishment of PHSEM provides a new idea for creep research in practical engineering.
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Influence Mechanisms of Inner Loop Inductance in High Frequency Hybrid Switch Turn-off Process

Jiang Pei Xuan, Wang Jia Lu, Gao Yu Heng, Wang Xiao, Chen Xian Ping, Wang Ping

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Hybrid switch (HyS) is a new type of module with parallel applications of power semiconductor devices of different materials, structures and characteristics, which owns disruptive advantages at power loss and economy with coming of the third semiconductor devices in the new era of clean energy. For higher frequency applications of hybrid switch, based on circuit behavior analysis and semiconductor devices characteristics, this paper proposed the equivalent models of the fast turn-off process of high frequency hybrid switch with inner loop inductance considered, where relevant influence mechanisms were deeply explored. LTspice simulations were applied to demonstrate the intuitive impacts on the turn-off characteristics of hybrid switch by inner loop inductance. And the according high-precision double-pulse test (DPT) platform was designed and built to test the turn-off process of different combinations of hybrid switch with a range of inner loop inductance level, where the experiment results sufficiently verify the validity of mechanism analysis and the proposed models. This work also provides theoretical basis and practical reference for future designs of high frequency hybrid switch.
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Modeling of GaN-HEMT small-signal equivalent circuits based on poles and residuals

WANG Yang-Huai, Wang Jun

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A modeling method of GaN-HEMT small signal equivalent circuit based on poles and residuals is proposed. Firstly, the poles and residuals of the accurate GaN-HEMT small signal model based on rational function are established by using vector fitting algorithm to reasonably fit the whole wideband measurement Y parameter of the device. Then, according to the different residual properties, the equivalent circuit model to realize the residual is discussed. Finally, a second - and third-order small-signal equivalent circuit model is established using poles and residuals. ADS software simulation verifies that the model has higher accuracy. The results show that the average relative error of S-parameters of the model is less than 1%, which is much lower than the traditional model. The problem of large error of traditional small-signal equivalent circuit model at high frequency is solved effectively. The proposed small-signal circuit model belongs to the research method of mathematical fitting model in essence, which is highly robust and can be applied to other similar transistors to improve practicability.
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Adaptive Image Semantic Captioning of Sight word Based on Transformer Network

liuzhongmin

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Aiming at the problems such as insufficient extraction of visual feature information and defects in distinguishing visual words from non-visual words in the process of image semantic captioning, a visual word adaptive image semantic captioning method based on Transformer is proposed. Channel self-attention module and adaptive attention module integrating DeBERTa pre-trained language model are used to improve the image captioning method, which is used to enhance the expression of visual signals and language signals. Firstly, ResNeXt-152 network is used as the backbone network for image feature extraction. In the feature extraction stage, ECANet channel attention mechanism is introduced to combine with self-attention in Transformer encoder to form channel self-attention module, to enhance the accuracy of feature extraction and strengthen relevant areas. Secondly, an adaptive attention module based on DeBERTa pre-trained language model is proposed to process visual words and non-visual words effectively, to measure the contribution of visual signals and language context to the generation of image captioning words. Finally, AdaMod optimizer is used to obtain the optimal network parameters, and cross-entropy loss is used to train the model. The experimental comparison was carried out on MS COCO benchmark dataset, and the effectiveness of the model was verified through quantitative evaluation and qualitative analysis. The experimental results showed that the scores of BLEU-1, BLEU-4, METEOR, ROUGE-L and CIDEr were significantly improved, among which the CIDEr index was increased by about 2%. Compared to the general Transformer model, it can make the statements describing the image more accurate and detailed.
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Lightweight Micro-expression Recognition Method Based on Sparse Inverse Covariance Estimation

luohong, caifenglin, yangtongxin, make, wangnan

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To address the limitations of traditional convolutional networks in handling partial correlations and feature redundancy, leading to suboptimal facial expression recognition accuracy, this paper proposes a lightweight micro-expression recognition method. This method enhances image classification performance by integrating Sparse Inverse Covariance Estimation (SICE) and Spatial Channel Reconstruction Convolution (SCConv). Initially, incorporating SICE as a new network layer into ResNet50 enables the model to more effectively identify and utilize partial correlations among features, helping to reduce bias caused by confounding variables. Subsequently, the introduction of SCConv, replacing standard convolutional layers, optimizes the model structure through Spatial Reconstruction Units (SRU) and Channel Reconstruction Units (CRU). Finally, experimental results indicate that the facial expression recognition network based on sparse inverse covariance estimation achieved a classification accuracy of 90.75% on facial expression data, significantly outperforming other network models. The studied model demonstrated a reduction in both parameter count and computational cost, with values of 20.13M and 3.61GFlops, respectively, when compared to other models. This suggests that sparse inverse covariance estimation combined with spatial channel convolution can further enhance classification performance in facial expression image.
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Comparison of application effects of water-side and air-side economizers in a data center

Jiang hang, Lizuoyang, Xuelian Bai

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While data centers consume a lot of energy, the consumption of water resources cannot be ignored. Air-side economizer, an effective energy-saving technology for data centers, is constrained by outdoor air pollutants. Based on the actual energy consumption, water consumption and air conditioning test data of a data center, taking into account the indoor environmental requirements and the outdoor air pollutant conditions of the data center, the feasibility of applying the air-side economizer was discussed and its calculation method of energy and water consumption was analyzed, and the calculation results were compared with the actual application of the water-side economizer. The results show: The data center has a Power Usage Effectiveness (PUE) of 1.56 and a Mechanical Load Component (MLC) of 0.43 under mechanical cooling and significant energy savings under full free cooling in the water-side economizer, with a PUE of 1.40 and MLC of 0.25. Compared with the period of applying water-side economizer, the PUE of applying air-side economizer is 1.27, MLC is 0.13, the average daily water consumption is about 30% of the cooling tower water consumption, and the Water Use Efficiency (WUE) is 1.01, so the energy and water saving potential is much higher than that of water-side economizer. In addition, the water-saving performance of the air-side economizer will be further improved as the specification requirements for the lower limit of humidity in the data room environment are reduced. This provides a basis for subsequent research on the combination of air-side and water-side economizers , as well as for proposing the idea of " air-side prioritization, water-side supplementation".
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Experimental Study on Axial Compressive Performance of Assembled Square Pier with Tenon and Mortar Sleeve Hybrid Connection

linshangshun, heyue, xiazhanghua, qinzhiqing, zhangletong, linyongjie

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Existing studies have shown that the seismic performance of the mortise and grouting sleeve mixed connection assembled square pier (referred to as the mixed connection assembled pier) is close to that of the integral cast-in-place pier. In order to further explore the axial compression performance of the mixed-connected bridge piers, the length, diameter and wall thickness of the steel pipe are used as the variable parameters,Carry out the axial compression bearing capacity test of 1 integral cast-in-place bridge pier (No. ZT) and 4 mixed connection and assembled bridge piers (No. GTA-0~GTD-0), The results show: The bearing capacity of GTA-0~GTD-0 specimens is 10.1%~14.4% higher than that of ZT specimens, and their ductility coefficients are all greater than that of ZT specimens; The axial compression bearing capacity of GTA-0~GTD-0 specimens increases with the increase of the diameter and length of the steel pipe, while the wall thickness of the steel pipe has a small effect on the bearing capacity of the specimen;The damage position of the assembled bridge pier moves upward with the increase of the steel pipe length, and gradually approaches the integral cast-in-place bridge pier, but the failure modes of the two are basically the same. Relevant research conclusions can provide reference for engineering design.
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Study on the combined stress of polystyrene nanoplastics and Cu2+ on Pseudomonas stutzeri

Mengweile, Qu Jianwei, Huang Jie, Yang Rui, Xu Xiaowei, Chen Youpeng, Yan Peng, Fang Fang, Guo Jinsong

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Polystyrene nanoplastics (PS-NPs) and Cu2+ coexistence in wastewater can induce a compound stress effect. The growth, nitrogen removal, and biochemical characteristics of aerobic denitrifying bacteria (Pseudomonas stutzeri) were investigated under PS-NPs and Cu2+ stress conditions, while the stress mechanism was elucidated through transcriptomics analysis. The results showed that under the stress of 50 mg/L PS-NPs, the bacteria exhibited an 25.3% increase in growth activity compared to the control group, accompanied by enhanced nitrogen removal activity and significant upregulation of ribosome, TCA cycle, and ABC transport pathway. Under the stress of 10 mg/L Cu2+, the growth activity of the bacteria decreased by 83.2% compared to the control, and the bacteria was significantly inhibited. The cell membrane was damaged, and the metabolic pathways related to ribosome, nitrogen metabolism, and ABC transport were significantly downregulated. The genes related to extracellular polymeric substances (EPS) secretion, cell membrane synthesis were significantly upregulated. Under compound stress conditions, Cu2+ stress exerted dominant effects. However, PS-NPs exhibited the ability to stimulate enhanced EPS production. Additionally, both PS-NPs and EPS demonstrated the capacity to adsorb a portion of Cu2+, thereby alleviating the detrimental effects caused by Cu2+ on the bacteria. These results provide theoretical insights into utilizing aerobic denitrifying bacteria for treating nanoplastics and heavy metal wastewater.
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Coordination model for multi-finger synchronous key-touchingin weak-finger piano playing

DING Baihui, LIN Jialuo, LI Zheng, SONG Zilong, LI Shengchao

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The investigation of the coordination of multi-finger synchronous key-touching in professional pianists holds significant importance in evaluating the training effectiveness for piano novices, human-machine collaboration control of piano teaching robotic hands, among other domains. Currently, the analysis of characteristics in piano key-touching actions primarily utilizes empirical formulas, focusing on single-finger key-touching movements. Addressing the limitation of the empirical formula's applicability and the lack of accurate and practical modeling methods for multi-finger synchronous key-touching actions, a modeling approach based on the sparrow search algorithm (SSA) and back propagation (BP) neural network is proposed. Given the uniqueness of the weak-finger, the research concentrates on the key-touching actions of the weak-finger assisted by the middle finger. Data were collected on multi-finger synchronous key-touching in weak-finger piano playing from twelve professional pianists utilizing a Leap Motion sensor. A coordination model, based on a BP neural network for multi-finger synchronous key-touching in weak-finger piano playing, was established and optimized using the genetic algorithm (GA) and SSA. The results demonstrate that the SSA-BP neural network-based coordination model exhibits enhanced predictive accuracy, with a root mean square error (RMSE) of 4.7226°. Based on this model, the key-touching movements of the weak-finger MCP joint can be accurately predicted from the key-touching movements of the middle finger, providing an evaluative method and scientific guidance in training for multi-finger synchronous key-touching in weak-finger piano playing among learners.
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Simulation of underwater current field communication with arrayed polar plates

FuGuoHang, JinJianHui, Li Shenghong

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In addressing the current challenges of complex underwater wireless communication antenna structures, difficult deployment, and severe high-frequency attenuation, a communication system based on an array of plate elements utilizing the electric current field is proposed. At the transmitting end, a plate array is employed to enhance signal reception intensity. Drawing on current field theory, the underwater array plate transmission formula is derived. Through finite element simulation analysis of signal strength and electric field distribution characteristics under different array quantities and communication distances, the impact of adding insulating materials and altering the depth of submersion at the transmitting end on reception effectiveness is analyzed. An experimental platform was set up to test 1×2 and 1×4 plate arrays, validating the influence of frequency and array quantity on reception effectiveness. The experimental results indicate that in low-frequency states, maintaining constant transmission voltage amplitude and power, arranging the transmission plate in an array, and adding insulating material at the transmitting end contribute to improving received signal strength. Additionally, parallel arrangement of the transmitting and receiving ends results in better reception. Precise control of the quantity and arrangement of plate arrays can facilitate long-distance underwater communication, providing valuable insights for the research and optimization of underwater electric field communication systems.
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Adaptive Cruise Control of Independent Drive Electric Vehicles with Integrated AFS and DYC Technologies

YE Zimo, YAO Chuyang, FU Chunyun

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For the configuration of Four Wheel Independent Drive Electric Vehicles (4WIDEV), an adaptive cruise control system integrating Active Front Steering (AFS) and Direct Yaw-moment Control (DYC) has been developed. This system is based on a dual-layer control architecture. The upper-level controller employs a Model Predictive Control (MPC) strategy to precisely track the vehicle's desired longitudinal force and additional yaw moment. The lower-level controller utilizes the control redundancy of AFS and DYC to optimize the calculation of the additional steering angle for the front wheels and the torque distribution for all four wheels, enhancing the vehicle's stability and economy. Simulation results indicate that, compared to traditional average torque distribution strategies, this integrated control strategy can achieve up to 13.02% energy savings while ensuring vehicle stability. This research provides new insights into enhancing the comprehensive performance of 4WIDEV.
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Anomaly Identification for Natural Gas Dewatering Equipment Production Process with Time-varying and Multiple Operating Conditions Data

Zhao Yong, He Yanlin, Wu Qianying, Ren Hongji, Yin Aijun, Li Qin

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The complexity of natural gas production processes and the variety of parameters and working conditions makes it difficult to identify abnormalities of operation processes. To address this problem, we proposed an anomaly identification method for natural gas dewatering process based on adaptive Gaussian mixture model (AGMM) and principal component analysis (PCA), namely anomaly identification for multi-case time-varying data (AIMT). AIMT uses sliding-window PCA to update the master metamodel of the monitoring data for the description of the working process based on AGMM. Adaptive optimization of the parameters of each Gaussian model in AGMM is carried out through a large amount of historical monitoring data in order to achieve effective characterization of complex multiple operating conditions. The identification of process anomalies is realized by squared prediction error (SPE) and Hotelling's T2 (T2). The effectiveness of the method proposed in this paper has been verified by data from single condition, variable condition, and multiple condition operations and real failure events in an expanded 1 million triethylene glycol (TEG) dewatering equipment at Chongqing Gas Field, PetroChina Southwest Oil and Gas Field Company.
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Research on the Wide-Band Model of Power Capacitors and Loss Analysis

ZhangZheng, DuLin, ChenWeigen

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In the power system, power capacitors play the role of reactive power compensation, filtering, carrier wave, and high-frequency protection. With the rapid development of the power system towards the "dual high" characteristic, the voltage signal applied to the power capacitor contains a large amount of harmonic voltage, which exacerbates the uneven distribution of voltage and current signals on the capacitor plate. The heating and aging of power capacitors are closely related to their active power losses. Therefore, considering metal and dielectric losses, a wide-band distributed parameter equivalent model of capacitors under harmonic voltage is proposed. The voltage and current distribution characteristics and loss analytical expressions are derived, and calculations are carried out to analyze and summarize the law: under harmonic voltage, the current flowing through the capacitor plates increases, The metal loss and dielectric loss of the electrode plate have significantly increased, presenting an uneven distribution. The loss generates heat, which affects the insulation and operating status of the capacitor.
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Study on damage process and failure mode of stratified shale under uniaxial load

CHEN Mei-ling, GUO Hong-guang, DONG Zhi, MENG Zhen-jiang, WU Yan-cheng

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Low permeability is one of the main factors restricting shale gas exploitation, and the type and complexity of fractures in rock mass are the key factors restricting permeability. Therefore, strengthening the study of shale damage and failure process is of great significance for improving the efficiency of shale gas exploitation. In view of this, based on the method of combining experiment and numerical simulation, the mesoscopic crack evolution, macroscopic crack fractal, damage evolution process and damage influencing factors of stratified shale under uniaxial load are deeply studied. The results show that the development of micro-cracks showed a trend of "steady rise - basically stable - rapid rise" during the loading of specimens. In terms of the stages of micro-crack development, the development of tensile cracks is the main at 0 degree and 90 degree bedding angles and its proportion is 94.7 and 96, while the development of shear cracks is the main at 30 degree and 60 degree bedding angles and its proportion is 65 and 86.9. The macroscopic failure cracks have obvious fractal characteristics, and the fractal dimensions of macroscopic cracks are 4.25, 3.44, 2.06 and 3.60 at 0 degrees, 30 degrees, 60 degrees and 90 degrees of bedding angles. The law of damage development affected by bedding. The damage is concentrated in the matrix at 0 degree and 90 degree bedding angles and is concentrated in the bedding at 30 degree and 60 degree bedding angles. In addition, the damage affected by the heterogeneity and anisotropy of the rock. For example, with the increase of the variance of the elastic modulus, the homogeneity of the specimen weakened and the damage range under the same load enhanced, while with the increase of the bedding stiffness, the anisotropy of the specimen weakened and the damage range under the same load enhanced.
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Decentralized coordination optimization method for coordinate secondary voltage control in large city grid

WANG Xinling, YAN Wei, JIANG Wang

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With the increasing proportion of renewable energy and the decreasing installed capacity and operating hours of thermal power units, the phenomenon of "hollowing out" of power supply in load centers of power grids in large hub cities is becoming more and more prominent, which brings new challenges to regional reactive voltage control of secondary voltage. Therefore, a coordinated secondary voltage control optimization method is proposed for the "hollowing out" power grid. Compared with the existing research methods, the new method has the following characteristics: (1) The high-voltage busbar of all controlled power plants in the region is generalized to the voltage dominant node, and the goal is to minimize the square sum of the deviation between the high-voltage busbar voltage and its ideal voltage to achieve the optimization of the secondary voltage control; (2) The coordination relationship between the level and the upper and lower levels is distinguished, and the coordination variables of the threshold reactive power and threshold voltage between the upper and lower levels are added as well as the ideal deviation control objectives. The new method improves the secondary voltage control effect of the power supply "hollowing out" load center network through the generalization of the leading node and the coordination of the reactive voltage of the upper and lower regional gateways. Finally, the effectiveness of the proposed method is verified by simulation with the standard example combined system and the actual data in China.
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Flexible braking strategy and parameter optimization of AC excitation motor with high inertia load

ZHAO Jinglin, XIANG Xuewei, LI Hui, LI Wendong, LI Shuai

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AC excitation motors have the advantages of constant frequency in variable speed and power decoupling in steady-state, which have significant advantages in applications such as pumped storage and flywheel energy storage. However, the above scenarios require motors have ability to brake in emergency with large inertia load, and the traditional mechanical braking strategies don’t satisfy the requirements. A flexible braking strategy and control parameter optimization method are proposed for motors with large inertia load. Firstly, based on the structural characteristics of rotor, flexible braking strategy is proposed that the rotor connect to DC excitation power and the stator connect to multi-stage resistors, then derive the equivalent circuit in braking procedure. Secondly, establish braking parameter optimization model with multi-stage braking resistance, rotor excitation current, and speed of switching resistance as variables, rated motor parameters and braking resistance power as constraints, and the shortest braking time as the objective, then use genetic algorithm to solve the model. Finally, analyze the multi-stage resistance braking results and influencing factors through Matlab/Simulink simulation, and establish 7kW AC excitation motor platform to verify the simulation results. The results show that adopting multi-stage resistance flexible braking strategy can effectively reduce braking time, and optimizing braking parameters can achieve the shortest braking time and satisfy system power constraints, while balancing braking effectiveness and the economy of braking device.
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Mechanical properties and macro and micro failure characteristics of freeze-thaw damage of double-fissure limestone

Wu Xiaogang

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The deformation and damage to cold-region rock masses caused by repeated freeze-thaw cycles constitute a pressing forefront issue in need of immediate research and resolution. To investigate the freeze-thaw damage characteristics of fractured rock formations, freeze-thaw cycling and uniaxial compression tests were conducted on bifurcated gray limestone, varying the fracture angles. These experiments yielded the corresponding stress-strain curves and macroscopic failure features, with the utilization of scanning electron microscopy to analyze the fine structural attributes of the fractured surfaces.The experimental results reveal that bifurcated gray limestone exhibits pronounced brittle failure characteristics. Both peak stress and elastic modulus increase with the enlargement of fracture angles but decrease with an increase in the number of freeze-thaw cycles. Peak strain increases with the growth of fracture angles and the frequency of freeze-thaw cycles. The predominant macroscopic failure mode primarily entails a cracking pattern, with spalling as a secondary mode. The failure surfaces are closely associated with pre-existing fractures, primarily manifesting as tensile cracks. When the fracture angle is less than 90°, penetrating fractures traverse both pre-existing fractures, whereas at a fracture angle of 90°, the penetrating fractures exclusively follow the pre-existing fracture ①. Notably, the spalling mode exclusively manifests when the fracture angle is less than 90°. Importantly, pre-existing fractures exert minimal influence on the fine structural characteristics of the fracture surfaces. Nevertheless, microscopic crack attributes, including average length, cumulative length, and average width, increase with each successive freeze-thaw cycle. The enlargement of fracture angles serves to mitigate the damage induced by freeze-thaw cycling, thereby enhancing the overall durability of the rock mass. The research outcomes provide significant reference value for cold-region mining engineering operations.
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A High-Precision Low-Order Intersection Flow Distribution Model for Road Major Drainage

Shao Zhiyu, Ren Yuting, Sun Zhuo, Xu Lei, Feng Wang, Zhang Qi, Gong Huafeng, Chai Hongxiang

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During extreme rainfall events, urban roads functioning as surface runoff conduits in conjunction with drainage systems represent an economically efficient technique for flood mitigation. However, due to the lack of available calculation tools for flow diversion at road intersections, it is difficult to determine the drainage flow of downstream road sections, resulting in obstacles to the application of this technology. This study focused on T-shaped intersections within urban road networks and conducted hydraulic experiments and Computational Fluid Dynamics (CFD) numerical simulations for three distinct downstream boundary conditions: free outflow, backwater at main road end, and backwater at both road ends. A high-precision and low order intersection flow diversion model was constructed using the obtained data, with a calculation error basically within ± 15%. The flow diversion model provides a direct and straightforward computational tool for engineering applications. Also, it allows seamless integration with the widely used one-dimensional urban hydrological model SWMM (Storm Water Management Model), significantly enhancing the computational accuracy of the SWMM model at intersection nodes, thereby enabling the precise design of the entire large-scale road major drainage system.
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Dynamic response characteristics of tower-line systems after ice-shedding from conductors with non-uniform icing

liu qinyu, yan bo, wu kaiwen, yang hanxu, lu jun, liang ming, liu jiong

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Variation of ice thickness with altitude results in non-uniform icing distribution on conductor lines. The non-uniform icing and ice-shedding are defined and numerical simulation method for the dynamic response of tower-line system after ice-shedding from conductor with non-uniform ice are carried out with additional element method. The finite element models of typical isolated and multi-spans tower-line coupling systems of 500kV quad-bundle transmission lines are established, and the dynamic responses of the tower-line systems after ice-shedding from the conductor lines with non-uniform icing are numerically simulated. The dynamic response characteristics of the tower-line systems, including the stress distribution and load impact factor of the towers, the maximum reaction force at the connecting points, longitudinal unbalanced tension and jump height of the conductor lines after ice-shedding, vary with structural, icing and ice-shedding parameters are analyzed. The strength of towers under extreme conditions is also analyzed. The obtained results provide important instructions for the design of tower heads in the transmission lines in ice zones.
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FAULT DIAGNOSIS OF REFRIGERATION EQUIPMENT BASED ON DATA ENHANCEMENT AND CLASS FEATURE AGGREGATION MODEL

wang feng, song xin, ren hao, chen zhikui

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It is difficult to obtain enough samples for fault diagnosis of refrigeration equipment, which limits the performance of fault diagnosis models. To alleviate this problem, existing fault diagnosis algorithms for refrigeration systems first augment data with the data enhancement technology, then utilize the data filtering algorithm to filter low-quality samples and finally predict the fault types,. During the entire process, it is necessary to manually set appropriate thresholds for filtering samples, which is not applicable to automated industrial production. Moreover, existing methods only learn class information from augmented data, which neglect learning the relationship between samples of the same class. To alleviate the manual intervention problem while preserve the high accuracy of the fault diagnosis model, a novel fault diagnosis approach based on data augmentation and class feature aggregation model is proposed, which simultaneously implements data enhancement and fault diagnosis. In addition, a class feature aggregation module is embedded into the fault diagnosis model to ensure that sample features of the same class are close to each other, thereby improving the accuracy of fault prediction. The experimental results show that this method can be well applied to fault diagnosis of refrigeration equipment.
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Dynamic early warning model for online monitoring of wind turbine icing

HU Qin, RAO Lipeng, WANG Li, JIANG Xingliang, SHU Lichun

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Ice-covering phenomenon is easy to appear on the surface of wind turbine blades during the cold wave, which will lead to problems such as reduced power generation capacity, unstable equipment operation and even failure. Therefore, it is of great significance to carry out the research on the early warning method of wind turbine ice-covering. This paper analyzes the SCADA operation database, constructs the feature quantity based on wind speed, power and temperature data, and establishes an early warning model for the occurrence of ice-covering events by using the random forest algorithm; through the real-time monitoring of the thickness of the ice cover by the rotating cylindrical array device, it establishes a real-time early warning model for the occurrence of the ice-covering events and real-time early warning dynamic mechanism. With the case of ice cover of 3.2MW wind turbine in Chongqing Wanbao wind farm, we carry out the test verification of ice cover warning. The results show that the test results of the ice-covering event occurrence warning model have a classification accuracy rate of more than 95%, and the ice-covering event warning is issued several times within 1 hour before the ice-covering situation of the wind turbine blade; the real-time warning model continues to issue warnings after the wind turbine is covered with ice, which shows that the model is able to continue to track the trend of the wind turbine"s ice-covering environment; and it is verified that the dynamic warning model can provide a decision-making basis for the safe operation and effective management of the wind turbine. It is verified that the dynamic warning model can provide a decision-making basis for the safe operation and effective management of wind turbines.
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Shed Optimized Design of Polluted AC Composite Porcelain Insulators

HU Qin, LIU Yuhao, QIU Ziwei, SHU Lichun, JIANG Xingliang

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The pollution flashover problem of composite pillar insulators, as one of the major faults in substations, can be effectively improved by optimizing the shed parameters. This paper proposes a shed parameter optimization method based on the physical model of composite post insulators. Firstly, through simulation calculation we studied the effects of the extension of the large shed overhang P1 and the shed spacing s on the electric field distribution. With the optimization target of reducing the average electric field Eav along the skirt or the non-uniformity coefficient f along the skirt, the parameter optimization range was obtained as 70 mm≤P1≤90 mm and 72 mm≤s≤92 mm, providing a parameter range for subsequent shed parameter optimization experiments. Then, using physical models of composite post insulator as test samples, artificial pollution tests were carried out to observe the flashover voltage, ultraviolet discharge photon number, and arc development path of the test samples. The optimal(maximum flashover voltage) shed parameters were obtained as P1=90 mm and s=72 mm, and the pollution flashover voltage of the optimized sample was increased by 18%. Finally, the simulation and experimental results were comprehensively analyzed, and the priority of simulation optimization criteria was proposed. The average electric field Eav along the skirt mainly affects the flashover voltage U50%, and the smaller the Eav of the test sample, the larger the U50% and the weaker the bridging and crossing phenomena of the arc; the non-uniform coefficient f along the skirt mainly affects the ultraviolet discharge photon number, and the smaller the f of the test sample, the fewer the ultraviolet discharge photon number. In the optimization strategy based on electric field simulation, the priority of Eav should be higher than that of f, and the surface creepage coefficient should be close to 3.5-4.0.
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Study on Microstructure and Wear Properties of Cold Sprayed Cu/W Composite Coatings

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Cu/W composite coatings with different tungsten (W) contents were prepared on pure copper (Cu) substrate using cold spraying technology. The influence of W content on the deposition characteristics and mechanical properties of the coatings was systematically studied. The microstructure, phase composition, microhardness, and friction and wear properties of the coating were characterized and analyzed using field emission electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness tester, and wear testing machine. The results showed that there was no oxidation and phase transition phenomenon in the cold sprayed composite coatings. The porosity of the coating with 10wt.%W content reached a minimum of 2.42%, and gradually increased with the increase of W content. The microhardness increases with the increase of W content, reaching a maximum value of 62.9HV0.2 in the composite coating with 30wt.%W content. Compared with pure Cu coatings, Cu/W composite coatings with 20wt.%W content showed an excellent friction coefficient and wear rate. This is attribute to that the addition of hard W particles has the role of compaction and second phase strengthening, which reduces the porosity of the coating and increases the microhardness. However, when the content of W particles increased, the soft phase Cu cannot effectively wrap the excess W particles, resulting in the spalling of W particles during the wear process, which induced the increase of friction coefficient and wear rate.
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The research on numerical differentiation applied to evaluate theory accuracy of device combination orbits

Wei Zhidong, He JIngjiang, Yang Han, Guo Maoyun, Chai Yi

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The theory accuracy evaluation of device combination orbit is the important base of device allocation design and selection of device combination trajectory. The Jacobian matrix of orbit about measuring element is the kernel of the theory accuracy evaluation model of orbit based on error propagation principle. However, it is hard to get the elements’ analytic expression of the Jacobian matrix of complex orbit equation. The theory accuracy evaluation algorithm of device combination trajectory based on numerical differentiation is raised and designed in the paper. By means of constructing numerical queue and calculating Jacobian matrix by numerical differentiation based on spline interpolation, and then the theory accuracy of device combination orbit is obtained. At the last part of the paper, the algorithm is verified to be effective and practical by compared itsJacobian matrix and accuracy value with single position equation’s.
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Axial compressive behavior of thin-walled multi-cavity concrete-filled double-skin (square inner and square outer) steel tubular stub columns

ZHANG Xiao, GONG Jun, SHAO Yongbo, HUANG Weifeng, LI Zijun

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To improve the axial performance of concrete-filled double-skin steel tubular (CFDST) stub columns, a novel thin-walled multi-cavity concrete-filled double-skin tubular (MCFDST) stub column is proposed and experimental investigations are performed to study the axial compressive behavior of MCFDST stub columns. Fifteen MCFDST stub columns and three CFDST stub columns are designed and fabricated. Four parameters considered in this study include concrete compressive strength (CCS), width-to-thickness ratio (WTR) of outer tube, hollow ratio (HR), and the presence of tension ribs. By analyzing the deformation, load-displacement curve, damage phenomenon,and ductility coefficient of stub columns, the ultimate bearing capacity,failure mode, and ductility performance are examined. The experimental results show that the bearing capacity increases by 46% while the ductility coefficient decreases by 74% when the CCS increases from 58 to 90 MPa. As the WTR decreases from 77 to 58, the bearing capacity increases by 12.5% and the ductility coefficient also increases obviously. The bearing capacity and ductility coefficient increase by only 1.3% and 1.0%,respectively,when the HR increases from 0.31 to 0.38. Significantly,the presence of tensile ribs increases the bearing capacity and ductility coefficient by 14.2% and 282%, respectively. Moreover, the effectiveness of numerical modeling method and the correctness of numerical model are verified using experimental data, and many finite element parameter analyses are carried out. The applicability of design methods in current specifications to the axial bearing capacity of this MCFDST stub column is discussed, indicating that the prediction formula in Japanese standard AIJ is suitable to estimate the axial compressive bearing capacity of MCFDST stub column.
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Utilization of earthwork and stone in mountain city engineering construction

zhulili, zhanghailong, huangkai, 张力, wangouyu

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In order to rationally utilize and scientifically absorb the abandoned area of engineering construction and realize the preservation and appreciation of natural capital, GIS technology and big data of survey information are introduced into the management of soil and rock of engineering construction in mountainous cities based on three-dimensional geographic information environment, and a scientific method of disposal of abandoned area of engineering construction is proposed. Using the methods of field observation, literature investigation and interview investigation, this paper puts forward the ways and methods of earth and rock resource utilization, realizing the resource utilization of earth and rock waste generated by traditional engineering and turning "waste" into treasure. Taking Beibei District of Chongqing City as an example, in the preparation of territorial spatial planning, we carry out the exploration and practice of the special planning of the resource utilization of earth and stone, analyze the classification and value and benefit of the resource utilization of earth and stone, and plan the site selection of the storage site in combination with the ecological restoration of the mine, so as to give full play to the role of territorial spatial planning in guiding, restricting and guaranteeing the implementation of the project, and realize the intensive and efficient use of earth and stone resources.
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Study on the mobile strategy of directed energy Transmitter in the RF Energy Har vesting Wireless Sensor Network

wanghaidong, SHANGGUAN Wujun, GUO Yina

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For the charging efficiency of mobile energy transmitter(ET) in RF energy harvesting wireless sensor network(RFEH-WSN),the existing work mainly assumes that the charging radiation range of mobile ET is circular, and the charging radiation range of mobile ET is usually set as a sector at a certain angle in practical applications. Aiming at the application scenario of directed mobile ET, this paper proposed a new multiple object model,and the optimization aims of the model are to minimize the charging time and to maximize the coverage, and uses Particle Swarm Optimization? to solve the optimal Pareto solution set. The results of simulation experiments show that the multi-objective optimization algorithm proposed in this paper can effectively improve the charging efficiency of mobile ET and is more suitable for nonlinear model.
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Linear Hall Sensors for Rotor Position Detection in external rotor Permanent Magnet Synchronous Motor

Xiaodong Cheng, Ciyong Luo, Sheng Zhou, Junfeng Zhao, Zihan Luo

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The traditional rotor position detection scheme is to mount Hall sensors on the motor stator or at the bottom of the motor, and calculate the rotor position by detecting the air gap magnetic field or permanent magnet leakage. However, armature reaction has great influence on the accuracy of rotor position detection. Thus, it is proposed to mount the Hall sensor on the printed circuit boards (PCB) outside the external rotor permanent magnet synchronous motor (PMSM). The permanent magnet of the motor is slightly higher than the rotor yoke, and the rotor position is detected by detecting the magnetic field of the permanent magnet, which is almost unaffected by the armature reaction. Theoretical and experimental analysis found that when the Hall sensors are mounted on the PCB at an interval of 90°, the fundamental wave phase of the two Hall signals is not orthogonal, resulting in an error in the rotor position. To address this problem, it is analyzed that the fundamental wave phase is orthogonal when two Hall sensors are mounted on the PCB at an interval of 90°?Pr/(Pr+1). Then the correctness of the theoretical analysis is verified based on ANSYS Maxwell finite element simulation as well as the physical experiment of the motor, and the feasibility of the position detection scheme is also verified.
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Smooth Transition Method for Sensorless Control of SPMSM

Xiao Wang, Jingyi He, Xiayang Hu, Mengye Chen, Letong Chen, Ciyong Luo

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For full-speed position sensorless control of surface-mounted permanent magnet synchronous motor (SPMSM), this paper presents a hybrid position sensorless control scheme based on combination of I/F control and nonlinear flux observer. In low-speed region, the I/F control method is utilized for the stable startup and reliable operation. In medium-speed and high-speed region, a nonlinear flux observer and a phase locked loop (PLL) is introduced for position estimation. In response to the common switching oscillation problem in hybrid control methods, this paper proposes a current fusion switching method based on PI control; And combine the linear extended state observer (LESO) with the current fusion switching method to further form compound switching method. In addition, simulations and experiments are designed to verify the switching performance of the two methods. The results show that both proposed methods can achieve smooth switching of control strategies, and compound switching method has better performance during the transition process.
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A detection algorithm based on YOLOv5s for metal surface defects

AN Zhiguo, XIAN Qinglin

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Metal parts are widely used in various fields such as production and life, and their surface defects are not evenly distributed and some characteristics are weak, which often causes missing and false detection. To solve this problem, the YOLOv5s-MD algorithm is proposed. In this algorithm, the XSPPF module is improved, the GSConv module is integrated, and the lightweight attention mechanism is added to improve the model"s ability to effectively acquire defect features at different scales. The SIoU loss function is adopted to consider the inconsistency between the predicted frame and the anchor frame due to the irregular and large difference in the size information of metal surface defects. The detection algorithm was trained and validated in the augumented metal surface defect dataset. The results show that the average precision of defect detection mAP@0.5 reaches 75.3%. The proposed detection algorithm can effectively improve the detection precision and reduce the false detection in the detection of metal surface defects.
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Contextual Disturbance-aware Correlation Filter Target Tracking Algorithm

HUANG Bo, ZHANG Hong, KUANG Yihao, WANG Jiaqi

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Discriminative Correlation Filters (DCFs) based trackers are subject to interference from background noises surrounding the target, which makes the DCF training easy to learn the filter from the contextual environment. To resolve this, this paper proposes a novel Contextual Disturbance-aware Correlation Filter (CDCF) target tracking algorithm, which establishes a background contextual disturbance model to guide the decision-making process of the tracker in the current frame. Firstly, CDCF employs the latest contextual background patches to generate a large number of negative samples through spatial cropping and correlation operations, followed by implementing them as a regularization term into the objective function. Secondly, CDCF incorporates an aberration repressed regularization term, which avoids the response map aberration problem caused by deformation, occlusion, etc., via the reuse of the filter knowledge learnt from the historical frames. Finally, an optimization method based on Alternating Direction Method of Multipliers (ADMM) is designed to achieve the implementation of the cropping operation in the spatial domain and the high-speed solution of the filter in the frequency domain. Quantitative and qualitative evaluations on OTB-2013 and OTB-2015 datasets demonstrate the effectiveness of the proposed algorithm.
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Analysis of time-varying seismic vulnerability of curved bridge in offshore atmospheric environment

hanzijun, liyongming, huangyu, dongqingshu, haoyuan

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The reinforced concrete structures in offshore atmospheric environment are eroded by chloride ions all the year round, and the seismic performance of the structures deteriorates continuously during the service period. In order to study the change law of seismic damage risk of reinforced concrete curved Bridges in offshore atmospheric environment, based on previous research results, this paper determined the probability distribution types of different environmental parameters and corrosion parameters, and built a probability-based reinforced concrete material deterioration model under chloride ion erosion effect. The finite element model of curved bridge under offshore atmospheric environment is established on OpenSEES platform, and then the time-varying seismic vulnerability of bridge components and system is analyzed respectively. The results show that, under the same intensity of seismic load, with the increase of service time, the exceedance probability of pier under various damage conditions increases, while the probability of support damage decreases slightly. With the increase of fortification intensity, the vulnerability curve of components tends to be flat, and the seismic capacity is constantly improved. In addition, the damage probability of the bridge system is higher than that of the component, so the vulnerability analysis results of the component and the system should be considered comprehensively when the seismic performance evaluation of the bridge structure is carried out.
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Friction and Wear of Fluoroether Lip Oil Sealand Aging Performance Test Analysis

liangxiaorui, chenlishan, mengfanming, gaozhiyuan, yangsheng

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Based on a multi-purpose transmission friction test bench, a variable speed dry friction test was conducted on a lip shaped oil seal made of fluoroether rubber material, taking into account different interference amounts and different media aging times. The effects of media aging time and interference amounts on the torque, vibration, and friction wear of the oil seal installation spindle were studied. The test results show that within the range of parameters selected, with the extension of aging time, the spindle torque decreases, and the vibration decreases first and then increases; With the increase of interference, the torque and vibration of the spindle increase. Moreover, the longer the aging time, the lower the interference, and the smaller the wear amount of the oil seal. In addition, with the increase of aging time, the smoother the friction surface of the specimen, and the more obvious the swelling phenomenon.
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PF-LBM simulation of Shear dynamic behavior of surfactant-laden droplets

Chentao, Yaoliping, Zhangliangqi, Zengzhong, Xieshouyong

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Surfactants can reduce the surface tension of fluid interfaces and significantly alter the wetting properties of solid surfaces, making them widely used in industrial production. In order to investigate the motion characteristics of surfactant-laden droplets on solid surfaces, a mixed model incorporating soluble surfactant flow and contact line dynamics was established based on the Cahn-Hilliard phase field lattice Boltzmann method, and the Yokoi dynamic contact angle model considering the speed of three-phase contact line movement obtained from experiments. A computational program was independently developed based on the governing equations, and parallel processing was used to improve computational efficiency. Subsequently, the dynamic process of droplets under linear shear was studied, and the influence of the effective capillary number (Cae) and the solid surface wettability on the deformation of clean droplets and surfactant-laden droplets was analyzed. The results show that the increase of the effective capillary number Cae promotes droplet deformation, but when it reaches a certain value, the droplet will rupture. While, surfactant-laden droplets exhibit the greater deformation and the movement speed compared to pure droplets. When droplets are attached to hydrophilic solid surfaces, they are further elongated under shear, exhibiting longer relative arc length and relative wetting length compared to neutral surfaces, while surfactant-laden droplets have longer relative arc length and relative wetting length compared to pure droplets. However, when droplets are attached to hydrophobic solid surfaces, they will detach from the solid surface under shear, and surfactant-laden droplets detach earlier than pure droplets. The research results indicate that the presence of soluble surfactants has a significant impact on the shear motion of droplets, promoting droplet deformation and increasing droplet movement speed. The numerical methods used in this study can be applied to calculate the moving contact line problem of droplets with soluble surfactants.
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Frequency domain detection method for railway signal cable faults

Jin Ke, Xu Zheng

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Fault detection of railroad signal cable is of great significance to the safe operation of railroad system. For the most common high-resistance fault problem of railroad signal cable, the inhomogeneous characteristics of railroad signal cable structure are analyzed by measuring the electrical parameters of several 1 m cables, and the normal model of cable inhomogeneous parameters is constructed, and finally the inhomogeneous high-resistance fault simulation model of railroad signal cable is established. The feasibility of the Frequency-domain reflection (FDR) method in locating high resistance faults in railroad signal cables is verified. And a hardware system is designed independently based on the FDR method, which transmits a 0.1~5 MHz sweep signal to the cable and collects the echo signal required by the FDR method through the intermediate frequency detector, and then subsequently carries out the data processing in the upper computer to realize the localization of high-resistance faults of 0.1 MΩ and 0.5 MΩ within 1000 m. The actual localization effect of the FDR method in detecting high resistance faults in railroad signal cables is verified.
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Research on anti-misalignment characteristics of LCC-S-LCC wireless power transfer system

ZHU Hai, GE Kailiang, ZHANG Yichuan

Abstract: (412) HTML (0) PDF (0.00 ByteKB) (0)

In the application of wireless power transfer(WPT) system in the field of electric vehicles, the misalignment of the primary and secondary coils is inevitable, which causes the output power to decrease. In order to the problem, this paper proposed to add a relay coil to the transmission side of double-sided LCC compensated wireless power transfer(WPT) system, thus forming a novel LCC-S-LCC three coil WPT system. Reduce the fluctuation of output power by reducing the sensitivity of mutual inductance between the relay coil and the receive coil to transverse offset distance. Finally, a prototype was built for experimental verification, and the results showed that within the range of transverse offset distances of 30% of the coil size, the output power fluctuation of the novel LCC-S-LCC three coil WPT system was only 5.5%.
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A Method of Patrol Image Enhancement Based on Wavelet Transform and Retinex-Net

liyouchun, tangchunjun, liangjiakai, luyaolin, xiemin, xumin

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Aiming at the problems of abnormal illumination and unobvious main features of the tower in the low-quality inspection image taken by UAV, an image enhancement method based on wavelet transform and improved Retinex-Net is proposed. Firstly, the low-quality image is decomposed into low-frequency images by wavelet transform, and the low-frequency images are processed by the improved Retinex-Net network. ASPP module and SE module are introduced to enhance the network feature extraction ability, and the feature map is scaled by using jump link structure and nearest neighbor interpolation method to reduce background noise interference. The contrast-limited adaptive histogram equalization algorithm (CLAHE) is used to enhance high-frequency images and reduce high-frequency noise interference. Finally, the enhanced low-quality image is obtained by wavelet reconstruction. Experimental results on self-built data sets show that, compared with HE and MSRCR algorithms, the proposed algorithm can enhance the edge features of image details, restore the image color, improve the resolution, help transmission line operators to monitor and improve the accuracy of analysis.
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Application of Improved Whale Optimization Algorithm in Motion Washout Simulator

Jia Lishan, xuhaijun

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Aiming at the situation that the parameters of the classical washout algorithm of the motion platform of the aircraft simulator are not selected properly, which causes a large error to the dynamic fidelity and affects the simulation effect, an improved whale optimization algorithm combining simulated annealing and adaptive variation is proposed. Combining with the vestibular system, a human perception simulation model is established, and the dynamic fidelity problem is transformed into the problem of finding the optimal parameters of the filter of the washout algorithm. The test function proves that the improved whale algorithm has better searching effect than traditional whale algorithm, particle swarm optimization algorithm and genetic algorithm. In addition, the simulation experiment also shows that compared with the classical washout algorithm and the traditional whale optimization algorithm, the improved whale optimization algorithm had the fastest convergence speed, the washout time was shortened by 83.3% and 33.4%, respectively, and the motion space was optimized by 45.2% and 26.1%. It is proved that the improved whale algorithm has strong robustness, and the simulation effect of motion washout is obviously improved.
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Urban sound classification method based on improved dual-channel 1DCNN

dongzhenan, xuepeiyun, baijing, gaoxiang

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A new urban sound classification method based on improved dual-channel one-dimensional convolutional neural network is proposed to improve the accuracy of urban sound classification and reduce the difficulty of model application. Firstly, the Fbank features of audio are flattened according to two different directions of the time frame and Mel frequency band to obtain one-dimensional data. Secondly, the two-dimensional convolution in the AlexNet model is replaced by one-dimensional convolution, and the model structure is improved. Moreover，according to different flattening methods, the receptive field of the first convolution is increased and the convolution step size is also increased to reduce the amount of feature data. Finally, a two-channel convolutional neural network model is designed using the modified AlexNet model and the decision fusion method. To verify the effectiveness of the proposed method, an urban sound classification experiment was carried out on the UrbanSound8K data set. The results show that the classification accuracy of the proposed method is 96.76%, and the size of the model can be effectively reduced, which is convenient for application in the scene with few storage and computing resources.
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Research on Hyperchaos Synchronization Control of Interval Type II Fuzzy Brain Emotional Learning and Its Application in Secure Communication

SUNYUAN, OUYANGSUJIAN, ZENG Huiquan, WANG Qinan, GAO Jiaqian

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Aiming at the problem that the performance of existing chaotic systems is insufficient in practical applications, this paper proposes a method to realize the synchronization control of hyperchaotic systems by combining interval type-2 fuzzy brain emotional learning (IT2FBEL) controller and robust controller. In this method, the IT2FBEL controller is used to approximate the unknown items in the hyperchaotic system, and the gradient descent method is used to update the weight and parameters of the IT2FBEL controller online to achieve the synchronous tracking of the hyperchaotic master system to the slave system. The robust controller is used to deal with the residual error of the system, making the output value of the controller approach the ideal control value as much as possible, and further improving the synchronization accuracy of the hyperchaotic system. Simulation results demonstrate that this scheme can achieve high synchronization of hyperchaos system and has better tracking performance and computational efficiency than RBF neural network, BP neural network and Brain Emotional Learning models. Additionally, simulation experiments were conducted for secure transmission of voice and image data. The results demonstrate the effectiveness and adaptability of the proposed method in the domain of confidential communication, providing further theoretical support for the practical application of chaotic secure communication.
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Mechanical activation strengthens the purification of cadmium from zinc powder in zinc sulfate solution

cuiwujiang, zengpeng, Zhen Yong, Li Xingbin, Wei Chang, Luo Xingguo, Zhou Zihao

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High single consumption of zinc powder and low cadmium content in purified cadmium removal residue are common problems in zinc sulfate solution zinc powder replacement for cadmium removal, and the core reason is that zinc powder is wrapped by the product layer to reduce its reactivity.Based on this, a new method for countercurrent replacement of two-stage zinc powder in enhanced zinc sulfate solution by mechanical activation was proposed, and zinc powder with a lower coefficient was added to produce advanced cadmium in the first stage, and zinc powder with a higher coefficient was added in the second stage to control the cadmium content in zinc sulfate solution to meet the quality requirements of solution purification. The results show that under the conditions of total zinc powder addition coefficient of 1.02, reaction temperature of 60°C and reaction time of 60min, when the addition coefficient of primary zinc powder is 0.9 and the addition coefficient of secondary zinc powder is 1.2, the concentration of cadmium in the liquid after primary purification is reduced from 1530mg/L before reaction to 60~70 mg/L, and the cadmium content in the cadmium residue produced by primary purification is enriched to 81.54%, and the zinc content is less than 10%. After secondary purification, the concentration of cadmium in the solution was reduced to 2~5 mg/L, and the cadmium content in the purification residue was 16%, and the zinc content was 55%. The main phase of the primary purification residue is elemental cadmium, and the main phase of the secondary purification residue is unreacted zinc and some elemental cadmium. Compared with the traditional primary purification process, through the shear stress and mechanical activation of the fluid, the wrapping layer on the surface of the zinc powder is destroyed, the wrapping phenomenon on the surface of the zinc powder is eliminated, the utilization efficiency of zinc powder is improved, the consumption of zinc powder is reduced, and the cadmium content in the purification residue is improved.
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Prediction of threshold value of creep stress of Ti60 alloy under fatigue-creep interaction

Zhao Hanbo, Zhang Jianyu, Liu Hao, Gong Yu

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Fatigue-creep interaction test was carried out on Ti60 alloy specimen at 550℃. Under the test conditions of fatigue stress ?max=450MPa and stress ratio R=0.1, the influence of different creep stress on fatigue-creep behavior of titanium alloy was studied. According to the test data and based on the Norton model, a new method was proposed which can be used to improve the fatigue-creep behavior of titanium alloy with limited samples. A prediction model that predicts the threshold value of creep stress over a longer period of time only through a short period of testing. The prediction results of this model are compared with those of the maximum axial stress method and those of the lifting method. The relative error is less than 2%. The results show that the prediction model can accurately predict the creep stress threshold under the fatigue-creep test conditions.
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Research on Stress Characteristics of Tower and Jump Height of the Ultra-high Voltage DC Lines in Ultra-heavy Ice Zone after Ice-shedding

Wang Wei, Yang Hao, Wang Qiang, Zhang Wanyi, Xue Tenglei, Yu Dongxu, GAO Yingbo, Yan Bo

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Mechanical characteristics of tower and maximum jump height of conductor after ice-shedding are key issue in the design of a tower head. Ice thickness of UHV DC line in ultra-heavy ice zones may arrive at 60mm~80mm, exceeding the maximum value proposed in current transmission line design codes. The finite element models of tower-line systems of UHV DC line sections in ultra-heavy ice zones are set up, and the dynamic responses of the systems with different spans after ice shedding are numerically simulated. Stress and longitudinal unbalanced trension on the towers and the maximum conductor jump height are obtained, and the mechanical characteristics of the towers and electric isolation clearance are analyzed. It is shown that the longitudinal unbalanced tensions are larger than those determined by current deighn code and the maximum conductor jump heights are larger than those by current formulus. The longitudinal unbalanced tension on the towers and the modification to the jump height formula are suggested.
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Improved product scale method for quantitative evaluation of tunnel lining crack diseases

shencaihua, MIAO Miao, BAO Xiyan, JIANG Yuke

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The cracking of tunnel lining structure is a key disease that needs to be prevented and controlled in tunnel maintenance work. The development of intelligent tunnel management urgently requires a quantitative evaluation method for the cracking disease of tunnel lining structure that can be promoted and applied. In this paper, the automatic recognition technology of crack image is introduced, and the quantitative evaluation index system and threshold determination method of single crack disease and m ulti crack disease of lining structure section are established respectively by fusing the product scale method and the specification requirements. The length and width of lining crack are taken as the main evaluation indexes for the diagnosis method of single crack disease, and the depth, direction and development of lining crack are taken as the auxiliary evaluation indexes; The diagnosis method for multi crack diseases uses the length and width of lining cracks as the main evaluation indicators, and depth, direction, development, and distribution density as auxiliary evaluation indicators; The determination of indicator threshold not only considers the probability distribution characteristics of uniform distribution function but also combines the safety characteristics of tunnel structure under stress. The scores of the evaluation method have been systematically standardized without dimensionality, and software that can be promoted and applied has been developed. Case analysis shows that this method is scientifically reasonable, providing a new way to achieve intelligent identification of tunnel cracking diseases and automatic decision-making of maintenance plans.
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Simulation investigation on lattice flow field of PEMFC

FENG Shiming, ZOULinhai, Zhang Yan, WANZhongmin

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The flow channel structure of a proton-exchange membrane fuel cell (PEMFC) has an important influence on the reaction gas flow, heat exchange, and electrochemical reactions.In order to address issues such as uneven distribution of reaction gases, liquid water management and output performance in common flow channels, our team designed three types of lattice flow fields.A three-dimensional proton exchange membrane fuel cell geometric model of traditional parallel flow field and lattice flow field was established, and the output performance, oxygen transport resistance, oxygen molar concentration uniformity coefficient, oxygen distribution and liquid water saturation were compared.The results show that compared with the traditional parallel flow field, the output performance of the three lattice flow fields is higher than that of the traditional parallel flow field, and the peak power density increases by 24.74%. The oxygen transport resistance of the lattice flow field is significantly smaller than that of the traditional parallel flow field. The molar concentration uniformity coefficient is significantly larger than that of the traditional parallel flow field.Moreover, the lattice flow field can significantly improve the uniformity of oxygen distribution and liquid water management inside the battery, and is expected to provide new ideas for fuel cell flow channel structure innovation.
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Research of the LQR algorithm with constraints based on preview control

jinyang, ouyangqi, lirui

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This study proposes a lateral and longitudinal control strategy for intelligent vehicles based on the preview control theory and linear quadratic regulator (LQR) to enhance the trajectory tracking ability and stability. The two-degree-of-freedom dynamic model of the vehicle and the road-vehicle error dynamic model is established, and the future road curvature is incorporated as a disturbance into the LQR state vector using the preview control theory. An augmented LQR problem is solved according to the optimal theory to obtain the analytical solution of the control quantity. This strategy also enhances the adaptive ability of the intelligent vehicle to extreme conditions by taking into account the dynamic constraints. The preview time is optimized using the simulated annealing algorithm to obtain the optimal preview time under different vehicle speeds and road friction coefficients. The stability of the closed-loop control system composed of the new algorithm is analyzed to verify its feasibility. Simulation results on the Carsim/Simulink joint platform demonstrate that it has excellent trajectory tracking ability, stability, and robustness to the vehicle speed. The proposed strategy has the potential to significantly advance the field of intelligent vehicle control and improve the safety and efficiency of transportation systems.
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Optimization of efficiency and analysis of energy saving and economy of modular thermo-activated wall

CHEN Sarula, CHEN Tianhang, YANG Yang

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A modular thermo-activated wall (MTAW) with special internal cavities for filling thermal diffusivity fillers is proposed to solve the problem of low-grade heat accumulation which restricts the improvement of heat injection efficiency of thermo-activated walls. The dynamic heat transfer model of MTAW was established., and performance differences between MTAW and two reference walls were compared based on typical winter conditions of the cold climate zone. The effects of the inclination angle (θ) and geometry size of the filler cavity (a:b), and thermal conductivity of the filling material (λf) on energy-saving potential and economics were discussed. Results show that the application of the filler cavity inside the wall and the filling of thermal diffusing material have a significant saving effect on the total operation energy consumption and operation cost. Compared with the two reference walls, when the long axis of the MTAW filler cavity is transverse and a:b is 1:2, the total operating energy consumption can be reduced by 2.60% and 14.13%. Compared with the two reference walls, the total operating cost of MTAW can be reduced separately by 12.41% and 50.04% respectively. When the long axis of the filler cavity is inclined to the room side, the heating energy consumption decreases first and then increases with the increase of θ, and the performance indexes are better when θL is 60°. The a:b and λf are inversely proportional to the total operating energy consumption and operating costs, and the reduction rate of heating energy consumption and operating gas cost can reach 3.03% and 34.53% respectively when the λf is 12λc.
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Study on Mechanical Properties of Microporous Layer Microstructure in Proton Exchange Membrane Fuel Cell

SHAO Xuanyu, HUANG Zhiping, XU Jie, ZHANG Heng, ZHAN Zhigang

Abstract: (319) HTML (0) PDF (0.00 ByteKB) (0)

The microporous layer plays an important role in the transmission of water, gas, heat and electricity in proton exchange membrane fuel cells,The deformation and microstructure damage under mechanical stress will seriously affect the transmission. The relationship between stress and strain is first obtained experimentally after fabricating the microporous layer and characterizing its microstructural properties. Then, the microstructure of the microporous layer is reconstructed numerically based on the microstructure characteristic parameters obtained from the experimental characterization. The displacement-stress distributions of carbon particles and polytetrafluoroethylene under different mechanical strains are obtained using finite element method. The results show that the mechanical action causes significant strain to the microporous layer microstructure of PEMFC, and strain located on the microporous layer surface is maximum, which is more likely to produce stress concentration. With the increase of mechanical strain, the stress increases exponentially in the direction of stress. When the strain is 10%, the maximum stress on carbon particles and PTFE is about 31.385 MPa and 14.873 MPa. When the strain increases to 40%, the maximum stress becomes 160.03 MPa and 96.165 MPa, and the stress concentration is the most obvious. The stress concentration area in the microporous layer will obviously increase with the increase of strain.
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Research on flexible exoskeleton knee joint control method based on STC-HOSMO

Luo Tianhong, Fang Shangchen, Ma Xiangyu, Fu Qiang, Ye QiangGuo

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Aiming at the retardation and bounded perturbation phenomenon of traditional pneumatic muscle knee joint, the dynamic equation of flexible knee joint of exoskeleton pneumatic muscle is constructed, and a Higher Order Sliding Mode Observer based Sliding Mode Control (STC-HOSMO) based on super-twist control algorithm is proposed. The algorithm realizes the motion control of the flexible knee joint by mapping the dynamic parameters of the flexible knee joint and the pneumatic artificial muscle. In order to verify the feasibility of the algorithm, a Matlab-Simulink simulation model and an experimental platform for flexible knee joint were built, and the simulation calculation and test data showed that the designed STC-HOSMO controller can control the joint with high motion accuracy and robustness under a large range of motion, and can effectively inhibit the traditional pneumatic artificial muscle robot joints that are prone to large jitter, hysteresis and bounded disturbances, showing high compliance. This paper provides a theoretical basis and experimental data for the application and development of flexible knee joint in exoskeleton R&D and design.
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Frequency Domain RC Coupled Dynamic Heat Transfer Model of Floor Radiating Room

chenjinhua, zhanghong, lulidi, shenxuelian

Abstract: (1104) HTML (0) PDF (0.00 ByteKB) (0)

In a room with a large glass area, the influence of solar radiation on the floor radiant air-conditioning system in summer cannot be ignored. Firstly, the projection equations method is used to solve the distribution of solar radiation in the room, and then a frequency-domain RC coupled dynamic heat transfer model of the room with floor radiation is established considering solar radiation. This model can perform dynamic heat transfer calculations for radiant floor rooms considering solar radiation, and solve the required node heat flow and temperature, and the calculation of variable working conditions is convenient. Using MATLAB software to write the calculation program of the model, and taking a certain working condition of a south-facing room in Chongqing as an example on July 21, the calculation found that: solar radiation significantly increases the floor surface temperature and indoor air temperature, which is conducive to improving floor cooling When only considering the external envelope structure load, the floor solar radiation heat gain accounts for an average of 16.75% of the total floor cooling capacity, with a maximum of 58%, and the solar radiation distributed on the inner and outer walls will increase its The radiation heat exchange with the floor, so the solar radiation cannot be ignored.
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Influence of FLUENT-based design parameters of sewage interception trunk on the total phosphorus concentration at the end of interception trunk

Zeng Xiangping, Fu Nannan, Ding Wenchuan, Tang Xinru, Wu Si, Zeng Xiaolan, Zhang Yu, Luo Wanshen

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When the agricultural non-point source runoff is transported to waste water treatment plant by sewage interception trunk around Dianchi Lake, the TP concentration will decrease along the way and be lower than the designed influent concentration at the end of trunk, which results in the failure of meeting the discharge standard. In order to explore the influence of main design parameters on end TP concentration and provide technical reference for the design of sewage interception trunk, the conducted research focused on the granular phosphorus in the agricultural non-point source transported by the well-constructed sewage interception trunk on the east bank of Dianchi Lake. The three-dimensional simulation software FLUENT was used to build the multiphase flow model of the fluid in sewage interception trunk and simulate the flow process. The influences of different section shape, roughness, hydraulic diameter, slope on the end TP concentration were analyzed. The simulation results show that the end TP concentration for the circular cross section is the lowest and is the highest for the trapezoidal section. With the increase of the roughness, the end TP concentration for the three section shapes increases, and there is a small variation range of the end TP concentration for rectangular section, while the largest variation range is for the circular section. With the increase of hydraulic diameter or slope, the end TP concentration for rectangular or trapezoidal section increases or decreases, while that of circular section decreases or has little change.
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Optimization of equal-cycle preventive maintenance strategy considering fault difference

LI Xinlong, Jiang Shuai, Chen, Chen Baojia, ZHANG Genbao

Abstract: (307) HTML (0) PDF (0.00 ByteKB) (0)

The equal-cycle preventive maintenance strategy is a common maintenance strategy, which has the characteristics of simple implementation. Aiming at the problem that the optimization modeling granularity of the The equal-cycle preventive maintenance strategy is a common maintenance strategy, which has the characteristics of simple implementation. Aiming at the problem that the optimization modeling granularity of the current equal-cycle preventive maintenance strategy is too large, and fault difference (the difference of preventive maintenance effects on different failures) is rarely considered, this paper takes the meta-action unit as the research object, divides unit failures into damage failures and intrinsic fatigue failures, and considers the difference of preventive maintenance effects on these two types of failures. The hybrid failure rate model is used to describe the imperfect maintenance effect, and an optimization model for equal-cycle imperfect preventive maintenance strategy is developed. Finally, numerical analysis is performed to verify the effectiveness of the proposed model and to analyze the influence of different maintenance costs on the optimal maintenance cost rate and the optimal maintenance strategy. It was shown that the maintenance cost rate of the meta-action unit would be underestimated without accounting for the difference of preventive maintenance effects; the different types of maintenance costs and the proportion of failure types have a significant impact on the formulation of the optimal maintenance strategy for the meta-action unit.
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Research on Vehicle-Goods Matching Based on View Similarity in Road Vehicle Transportation Problem

zhangjianhua, yangjiahe, caoziao, liujinyan, wangxiaohe

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In order to improve the vehicle loading rate and make full use of resources in vehicle transportation, this paper proposes a vehicle-cargo matching method based on view similarity in the way of the CBR system thinking. Firstly, the information of goods and vehicles is represented by the knowledge expression system, and the preliminary classification and matching of the two are realized based on the CR attribute of the vehicle and the N attribute of the goods; then, K-Means clustering is performed on the vehicle data set, and the Mahalanobis distance is used to calculate and match the information. Determine the cluster closest to the goods to be matched, and realize the lateral compression of the view matching space; finally, integrate and improve the traditional view calculation method, and use the Euclidean distance to calculate the view similarity between the goods to be matched and each vehicle in the given cluster, and submit the vehicle corresponding to the minimum view similarity. By crawling the Yunmanman platform data for experimental analysis, it is proved that the proposed method can significantly improve the loading rate of truck-cargo matching, and the matching efficiency is increased by about 76%.
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Prediction of fragrance retention grades of monomer flavors based on 3D graph convolutional neural network

Li Jiachang, He Jiafeng, Luo Dehan, Liang Jianyu

Abstract: (142) HTML (0) PDF (0.00 ByteKB) (0)

The prediction of fragrance retention grades (persistence) of monomer flavors is of great importance for the development of perfumery technology. Traditional methods are susceptible to subjective judgments and complex model decisions. Therefore, the paper proposes to investigate the three-dimensional dimension of monomer flavors and construct a monomer flavors retention classification framework based on a three-dimensional graph convolutional network (3DGCN) model. The 3DGCN model shows better performance in the task of predicting the fragrance retention grades compared to 2D research methods, especially when using set2set pooling in the graph aggregation stage, the classification results of the 3DGCN model with 82.06% accuracy, 82.34% precision, 81.98% recall, and 82.18% F1 score. This experiment is based on a three-dimensional graphical convolutional network framework for monomer flavors retention classification (MFRC-3DGCN), which provides a new dimension of data consideration for the prediction of fragrance retention grades and a reliable tool for the evaluation of fragrance retention grades properties of monomer flavors.
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Study on the influence of the occurrence state of soft interlayer on the rock slope of open-pit mine

fanhongzhi, wangguangjin, lanrong, liumingshneg

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As a typical geological structure, soft interlayer is a key factor affecting the safety and stability of the entire slope. In order to better analyze the properties of soft interlayers and their influence on slope stability, for a mine open-pit rock slope with soft interlayer, the orthogonal control method was used to simulate the four occurrence states of the sandwich depth, inclination angle, quantity and structural surface spacing between the layers of the slope soft interlayer, and the stability and deformation law of the slope were revealed under different occurrence states.The results show that: (1) The occurrence state of the soft and weak interlayer of the slope has a significant impact on the stability of the slope, and the safety factor of the slope increases with the increase of the burial depth of the soft interlayer, and the safety factor of the slope tends to be stable after the burial depth reaches a certain level. (2) With the increase of the angle of the soft interlayer, the failure mechanism is manifested as interlayer mismotion, creep slip along the layer and progressive change of shear-slip along the soft structural surface; (3) With the increase of the number of soft interlayer layers, the overall decline of the slope leads to uneven deformation, the safety factor of the slope decreases, and the horizontal displacement increases; (4) Compared with the soft sandwich slope with the same buried depth structural surface spacing is small, the structural surface spacing has less influence on the slope safety factor.
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Thermal noise analysis of an improved GaN HEMT model based on channel resistance RL

LIU Yuting, WANG Jun

Abstract: (285) HTML (0) PDF (0.00 ByteKB) (0)

This article proposed a method to improve the equivalent circuit model of gallium nitride high electron mobility transistors, utilizing channel resistance RL to improve the accuracy of the model.The mathematical correction method and direct extraction method are used to extract the parameters of various components in the small signal equivalent circuit and establish a small signal model. Based on this model, typical Pucel noise models and Pospieszalski models are used to model and simulate thermal noise at room temperature. By comparing the changes in model parameters before and after the improvement, the effectiveness and accuracy of the improved model were verified, which can be used to predict the noise performance of GaN HEMT devices. The results show that the improved model is more accurate than the traditional model, and the higher the gate bias or frequency, the greater the impact of RL on the model; Compared to traditional models, the improved model has a lower average value of the main noise figures, with a 1.7% reduction in the minimum noise coefficient NFmin and a 2.7% reduction in the equivalent noise resistance Rn, demonstrating good noise characteristics.
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Research on Heating Load Forecasting Based on the Bayesian Posterior Estimation of LSTM-XGBoost Combination Model

dai guan zheng, niu yu guang, ding ning, du ming

Abstract: (325) HTML (0) PDF (0.00 ByteKB) (0)

Improving the forecasting accuracy of heating load of district heating system (DHS) is an important method to realize intelligent heating and improve energy utilization efficiency. This paper proposes a combination heating load forecasting model based on Bayesian posterior estimation, Long Short Term Memory (LSTM) algorithm and eXtreme Gradient Boosting (XGBoost) algorithm. Initially, we confirm the input features based on the characteristics of heating load changes to construct the LSTM model and the XGBoost model respectively. Then, the Bayesian posterior estimation algorithm combined them to construct the LSTM-XGBoost combination model. The operating data of a heating station in Shijiazhuang from 2019 to 2020 was used for simulation validation, and the evaluation indicators of its results indicate that the Mean Absolute Percentage Error (MAPE) of the LSTM-XGBoost combination model based on Bayesian posterior estimation proposed is about 0.51%, which means the average deviation of heating load forecasting is about 0.51%. Comparing the proposed method with Recurrent Neural Network (RNN) model and Gate Recurrent Unit (GRU) model, and the result verified that the proposed method can effectively improve the accuracy of heating load forecasting.
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Solving nonlinear transient heat conduction forward/inverse problem based on physical-information neural networks

Chen Haolong, Tang Xinyue, Liu Zhaotao, Zhou Huanlin

Abstract: (676) HTML (0) PDF (0.00 ByteKB) (0)

A method based on the physics-informed neural networks (PINN) is proposed to solve the transient nonlinear heat conduction problems and estimate the temperature-dependent thermal conductivity. Firstly, a loss function is formulated with the residual error of partial differential equation, initial conditions and boundary conditions for the heat conduction problems. Then, the automatic differentiation is applied to acquire the partial derivatives of temperature in the partial differential equation. The heat conduction problems are solved by applying gradient descent algorithm to update the network parameters and to minimize the loss function. The influences of different numbers of hidden layers, neurons and interior collection points on the results are discussed. Finally, the PINN is applied to identify the temperature-dependent thermal conductivities. The loss function is formulated with the residual error of governing equation, measured temperature and computed temperature. The network parameters and thermal conductivity are updated by the gradient descent algorithm to approximate the exact solution. The influences of different measurement points and errors on results are also compared. The results show that the proposed method is an effective approach to solve the transient heat conduction problem and estimate the temperature-dependent thermal conductivity.
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GNSS/INS/OD Adaptive Integrated Navigation Method with Non Integrity Constraints under GNSS Lockout

ouyangqi, zhangxinyi, zhangxinglan, zhaohaihao, zhangjianyuan

Abstract: (451) HTML (0) PDF (0.00 ByteKB) (0)

For the GNSS/INS Integrated Navigation System in the loose coupling mode, the global satellite navigation system (GNSS) signal is vulnerable to environmental impact, which may lead to signal loss in some scenes. In view of the GNSS lock out situation, the non integrity constraint (NHC) is applied to the wheel tachometer (OD)/strapdown inertial navigation system (INS), which can effectively suppress the error divergence of pure inertial navigation in the case of GNSS signal lock out. At the same time, an adaptive Kalman filter algorithm based on innovation and an adaptive NHC noise method considering the vehicle motion relationship are proposed, which can effectively enhance the navigation and positioning ability in the GNSS lock out and vehicle turning scenarios. The verification of the scene measured data shows that the integrated navigation system using adaptive Kalman filter and adaptive NHC noise can ensure the navigation accuracy of "cm" level in the case of GNSS signal losing lock for 10s. Compared with the traditional extended Kalman filter scheme and the scheme using only adaptive NHC noise, its positioning accuracy is improved by 10%, and the speed measurement accuracy is improved by about 30%, which can meet the high accuracy of the navigation system in the GNSS losing lock environment High reliability navigation and positioning service.
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Photonics-based Microwave Correlative Interferometer Direction Finding Approach with Uniform Circular Array

Zhang Xianyu, AN Kang, LIANG Tao

Abstract: (224) HTML (0) PDF (0.00 ByteKB) (0)

As one of the mainstream direction finding schemes, correlative interferometer has many extraordinary advantages, such as low complexity computation, high accuracy, strong anti-interference etc. Besides, the uniform circular array can measure the azimuth angle and elevation angle simultaneously, and has the advantages of uniform direction finding accuracy and compact structure. Motivated by the above, this paper investigates the correlative interferometer direction finding using a uniform circular array. Since traditional electrical phase detectors are faced with some bottlenecks, such as bandwidth limitation, low frequency, electromagnetic interference etc., a photonic phase detector scheme has been presented to measure the phase difference. A dual-parallel Mach–Zehnder modulator (DPMZM) is adopted to construct an optical parallel interference structure which can estimate the phase differences by optical power measurement. The phase shift in DPMZM can be set to 0° and 180° by adjusting the DC bias. Then, the power of the output optical signal can be measured in both two cases. Besides, a Phase difference mapping function based on the ratio of optical power measurements has been proposed to improve the resolution of the power measurement and the estimation accuracy of the phase difference. Finally, the availability of the proposed scheme is investigated via experiments which shows that measurement error of phase difference is less than ±1° from 0° to 360° and the angle-of-arrival estimation error is less than 1.0082°.
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Research on fall Detection and Protection System based on SVM

PENG Lei, CAO Zhidong, CHAO Rui, LI Xiaohu, HU Jianhua, Li Xinchao

Abstract: (339) HTML (0) PDF (0.00 ByteKB) (0)

Real-time fall prediction and protection can significantly reduce the risk of fall injury and improve the self-care ability and physical and mental health of the elderly living alone. In order to improve the recognition accuracy, recall rate and specificity of the fall prediction algorithm, and reduce the fall discrimination and inflating time of the air bag protection system, a SVM-based multi-threshold fall prediction algorithm and air bag protection system were designed to realize the real-time prediction and protection of the fall behavior. Firstly, the acceleration sensor worn on the waist is used to collect motion data. Then, SVM algorithm is used to obtain the acceleration, acceleration and attitude Angle threshold of classified falls and daily behaviors. Finally, the prediction algorithm is reconstructed on the single chip microcomputer to realize the real-time prediction of falls and determine whether the air bag protection system is triggered according to the prediction results. The experimental results show that the recognition accuracy, recall rate and specificity of the proposed algorithm for falls are 97.3%, 99% and 96.1%, respectively. The average inflating time of the protective air bag is 350.4ms, which has the advantages of high recognition accuracy and short inflating time, thus strengthening the application of the system in real-time fall prediction and protection.
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Improved multi-objective slime mold algorithm to optimize the washing algorithm and simulation experiment

Li Jinxin, Wang Hui

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The parameter adjustment of the washing out algorithm has a great influence on the washing out effect. Aiming at the deficiency of the parameter adjustment of the classical washing out algorithm, an improved multi-objective slime mold algorithm is proposed to find the optimal parameter structure through this algorithm. Aiming at the initialization and local optimization problems of the standard slime mold algorithm, as well as the limited function optimization effect of solutions at non-origin, the Circle chaotic elite initialization population method was introduced, Levi Flight was introduced into the early position update formula of the standard slime mold algorithm, and the algorithm based on acquisition and shared knowledge was introduced into the later update formula, and the slime mold local optimization strategy was designed. Multiple objective functions are constructed by introducing Pareto non-dominated ordering. Human perception model, acceleration difference model and displacement model are established as objective functions, and their parameters are optimized. Finally, it is verified by simulation and experiment. The results show that the phase delay is improved by 41.7%, the working space of the motion platform is saved by 43.58%, and the washing effect is effectively improved.
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Loss optimization method for coupling mechanisms with layer gaps

Wu Jianhao, Wu Xiaorui, Xiao Jing, Gong Wenlan, Yu Jingyu

Abstract: (204) HTML (0) PDF (0.00 ByteKB) (0)

As the performance requirements of MC-WPT systems increase, the temperature of the coupling mechanism or the power conversion circuit of a high-power power transmission MC-WPT system can change or even damage the system if the temperature is too high. The control of the temperature has become the key to the long-term stability of high-power MC-WPT systems. Therefore, this paper proposes a loss optimization structure for the coupling mechanism with layer gaps. Firstly, we take the power transmission performance as the entry point to design a coupling mechanism that can transmit high output power under the size limitation of the coupling mechanism; secondly, we analyze the mechanism and optimization method of heat generation due to losses in the coupling mechanism; finally, we optimize the thermal performance of the coupling mechanism in terms of improving the heat dissipation structure and reducing the heat generation due to losses.
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Effect of carbonation on the properties of granite-bearing oxysulfate oxide cement

Jin Kairong, zhangxiaojing, BI wanli, wangdezhi

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The properties of magnesium oxysulfate (MOS) cement with different granite powder (GP) contents with CO2 curing were studied. The hydration products and microstructure of MOS cement were conducted by X-ray diffraction (XRD), simultaneous comprehensive thermal analyzer (TG-DSC), scanning electron microscope (SEM) and mercury porosimeter (MIP). The results shows that: the strength retention coefficient of MOS cement containing 40% GP reaches 1.12 with standard curing 28 d and then in CO2 for 28 d; when MOS cement with CO2 curing 28 d and then immersion in water for 120 d, the strength retention coefficient reaches 0.94, which is 123.8% higher than blank samples; MgCO3·zH2O crystals generated after MOS cement with CO2 curing, which has a positive effect on mechanical properties and water resistance of that via reducing matrix expansion caused by MgO hydrated to Mg(OH)2; GP increases the matrix dense, reduces CO2 capture rate and decreases CO2 erosion of MOS cement by optimizing the pore structure; GP and MgCO3·zH2O improves the carbonation resistance and water resistance of MOS cement.
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Analysis of single nuclei RNA sequencing data in autistic patients

CHEN Xiaotian, HE Xie, LIU Rui, WU Jinze, LI Yong

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In order to study the role of endothelial cell subsets in the blood-brain barrier of patients with autism spectrum disorder (ASD), a series of data mining methods were used to analyze the data set of single nuclei RNA sequencing in prefrontal cortex of ASD patients. First of all, the endothelial cells were divided into 4 subsets using graph clustering method. Then, the differentially expressed genes of each subset in ASD state were obtained by Wilcoxon rank sum test, KEGG enrichment and GO analysis were carried out. The results indicated that endothelial cell subset 1 was mainly involved in the changes of ATP synthesis and metabolism, mitochondria and activity of various enzymes such as oxidoreductase. Finally, the cell crosstalk between endothelial cell subsets and other cell groups in brain tissue was analyzed. The results showed that the number of endothelial cells receiving microglial signals increased in ASD patients; There may be specific SPP1 - (ITGAV+ITGB1) and SPP1 - (ITGAV+ITGB5) ligand receptor pair signals between endothelial cell subset 1 and microglia; At the same time, the number and strength of astrocyte signals received decreased.
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Research on Multimodal Information Fusion DynamicTarget Recognition Method for Autonomous Driving

Zhang Mingrong, Yu Hao, Jiang Libiao, Li Liping, Lu Lei

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The vehicle detection problem in the autonomous driving environment has many small targets and serious target occlusion, etc. In this paper, a multimodal information fusion dynamic target recognition method for autonomous driving is proposed.. The method mainly includes the following improvements: 1. Improved ResNet50 network based on spatial attention mechanism and hybrid null convolution: the 3×3 standard convolution in the conv2_x and conv3_x parts is replaced using selective kernel convolution, which allows the network to dynamically adjust the size of the perceptual field according to the feature size. The sawtooth hybrid null convolution [1,2,1,2,1,2] is used in the conv4_x part to enable the network to capture multi-scale contextual information and improve the network feature extraction capability.2. Switch to GIoU loss function: the localization loss function in YOLOv3 is replaced with the GIoU loss function, which has better operability in practical applications.3. Based on Two data fusion algorithm for human-vehicle target classification and recognition: A human-vehicle target classification and recognition algorithm based on two kinds of data fusion is proposed, which can effectively improve the accuracy of target detection. Experimental results show that compared with OFTNet, VoxelNet and FASTERRCNN, the mAP index can be improved by 0.05 in the daytime and 0.09 in the evening, and the convergence effect is better.
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Research on constant current/constant voltage output of electric vehicle wireless charging system and anti-offset magnetic energy coupling mechanism

Lu Hongchen, Dong Jinxi, Liu Xiliu, Chen Guanlin, Zhang Jinghai

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In the EV wireless charging system, the charging process of the loaded lithium battery is constant current followed by constant voltage. Therefore, the WPT system needs to have the ability to achieve two output states at the same time, and can smoothly switch between the two output states. Based on this, this article analyzes the conditions for achieving load independent constant current and constant voltage output in a bilateral LCC topology, and provides a parameter design method. In response to the possibility of random displacement in different directions in the system, a bidirectional coaxial planar coil structure is adopted, where the primary coil is composed of two coils wound in opposite directions, inner and outer, in series. The proposed EV wireless charging system has the ability to simultaneously achieve constant current/voltage output through simulation and experimental verification, and can still achieve stable output under multi-directional offset conditions.
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Anti-Deflection and interoperability study of WPT Based on Distributed Transmitting Coils

Shen Tao, Su Dong, Wu Zhanli, Dong Jingxi, Liu Xiliu, Wang Bo

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The offset of the relative position between the receiver and transmitter in the radio energy transmission system will affect the system transmission efficiency to a certain extent. In this paper, the full-range offset resistance and interoperability of the coupling mechanism are investigated in two aspects. A proposed many-to-one coupling mode is proposed, the transmit coil type is a planar distributed transmit unit coil combination, and the open mode of the distributed transmit coil is studied for different receive coil types, axial offset conditions and rotational offset conditions of the position mode to achieve interoperability and wide-range all-directional offset resistance of the receive coil. To improve the degree of freedom of the distributed transmit coil, a distributed series control logic circuit is proposed, and the resonance parameters of the transmit coil are designed for the series connection condition to reduce the effect of cross-coupling. The search strategy for receiving coil position detection is proposed by combining the magnetic field characteristics of the distributed transmit coil and the pickup voltage detection method based on the LCC-S resonant topology. An experimental setup is built, and taking the axial and rotational offsets of all positions into account, the maximum efficiency fluctuation of the planar receiving coil is 3.3%, the maximum efficiency fluctuation of the vertical receiving coil is 5.57%, and the maximum efficiency fluctuation of the solenoid receiving coil is 4.45%. The experimental results show that the proposed system has good antioffset characteristics and interoperability, verifying the feasibility and efficiency of the system.
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Design and Implementation of Power Recycling System in Discard Batteries Based on Long-Track MC-WPT

Wu Jianhao, Xiao Jing, Wu Xiaorui, Mo Yuhong, Liu Qiao

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The development of new energy and the application of a large number of batteries have also posed challenges to the recovery of residual energy from waste battery packs. To address the above issues, this article proposes an electric energy recovery system based on track type MC-WPT (Magnetic Coupled Wireless Power Transfer) technology, providing a new supplementary method for the recovery of residual electric energy from waste batteries. This system transports multiple sets of waste battery packs on the assembly line while efficiently transmitting their remaining electrical energy to the power grid, improving the energy recovery and utilization rate. This article improves the traditional track type MC-WPT coupling mechanism by using the non-track end as the energy transmitting end and the track as the receiving end. The system circuit topology is designed, a system mathematical model is established, and the transmission characteristics of the system under this coupling mechanism form are simulated and analyzed. Finally, a power recovery experimental platform was built, and four sets of waste battery packs were simultaneously recovered to the power grid on the track. The system input power was 1116.8W, and the energy recovery efficiency was about 82.4%. The experimental results verified the feasibility and efficiency of the system.
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Evaluation of the storage capacity of the saline aquifers in the Leikoupo Formation, Sichuan Basin

RAO Jie, XIE Jian

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The CO2 storage capacity of saline aquifers is a basic issue related to China's goal of carbon neutrality. The Sichuan Basin is an important oil and gas producing area in the southwest of the country, but there is still a lack of in-depth quantitative research on the CO2 storage prospects in its deep saline aquifers. The Leikoupo Formation T2l is a high-quality brine reservoir in the Sichuan Basin, and its fourth member T2l4, third member T2l3, and first member T2l1 can be used as target reservoirs for CO2 sequestration. In this study, based on the analytical solution to the overpressure induced by multiwell simultaneous injection, the MATLAB language script named CO2BLOCK is used to evaluate the CO2 storage capacity of the deep saline aquifers in the Leikoupo Formation. The results show that under the condition of continuous CO2 injection for 30 years, the CO2 storage capacity of the Leikoupo Formation reservoir in the Sichuan Basin is 0.83Gt, among which the storage capacity of the fourth member of Leikoupo Formation is the largest, the first member of Leikoupo Formation is the smallest. The maximum sustainable injection rate per well in the fourth, third and first members of the Leikoupo Formation are 0.550Mt/a, 0.051Mt/a and 0.054Mt/a, and the corresponding maximum sustainable overpressures are 3.09MPa, 5.67MPa and 6.55MPa. The economic optimal schemes (number of wells, well spacing) of the three reservoirs T2l4, T2l3 and T2l1 are respectively: (16,17), (20,17), (16,19), and the storage capacity corresponding to the economical optimal well arrangement scheme are 0.50Gt, 0.07Gt, 0.04Gt.
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Hybrid multi-strategy improved wild horse optimization algorithm and its application

Li Yancang, Wang Xiangchen, Yuan Qiuyu, Han Muxuan

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Aiming at the defects of late convergence speed, low search accuracy and low stability of wild horse optimizer, a hybrid multi-strategy improved wild horse optimizer was proposed. Firstly, Halton sequence initialization was used to increase population diversity. Secondly, the adaptive parameter was improved to balance the global search and local development capabilities. Then, the worst position of individual population was improved by simplex method. Finally, the escaping behavior was added to improve the optimization accuracy of the algorithm. In order to verify the effectiveness of the improved strategy, 9 standard test functions are selected for simulation experiments. The improved algorithm is applied to mechanical design problems and truss structure optimization examples, and the optimization results are reduced by 16.61%, 0.21%, 2.96% and 0.61% compared with the original algorithm. The statistical results show that the improved algorithm has higher optimization accuracy than the basic algorithm and other comparisons in solving practical engineering problems.
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Research on BPNN Modeling Based on GaN HEMT Parasitic Capacitance

QIN Shi-qing, CAO Tong, LI Ting, CHEN Fei-yu, Wang Zhong, WANG Fu-xue, HE Ying-yi, YING Jia-yao, YANG Guo-feng

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This article proposes a backpropagation neural network(BPNN) parameter fitting method to simulate the mapping relationship between the parasitic capacitance parameters and the gate source voltage of GaN HEMT due to its nonlinear characteristics under the influence of drain source voltage. The input layer of the neural network model is based on the GaN HEMT large signal parameter model and data manual, which extracts the parameter sampling points of parasitic capacitance related to the variation of leakage source voltage. This neural network model adjusts the weights of neurons by supplying error values to the output end to create a neural network training set that can adapt to the system mapping relationship, predict the connection between gate source voltage and parasitic capacitance in the actual open state of GaN HEMT, and link the acquired experimental data to the input layer for transmission. The BPNN model yielded a relative prediction error of 9%, demonstrating the efficacy of this method in predicting the behaviors of GaN HEMT devices. This technique simplifies the complexity of parameter extraction from physical models, thus facilitating the analysis and prediction of misleading situations.
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Numerical simulation of particle flow characteristics of opened and closed jacked pile penetration in Cohesive soils

WANG Yonghong, Yin Jinchao, ZHANG Mingyi, SANG Songkui, BAI Xiaoyu

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To investigate the penetration mechanism of jacking opened and closed pipe pile in the clayey soil, combined with particle flow numerical simulation software in dealing with the advantage of the large deformation and nonlinear problem, considering the contact adhesive model to simulate the superiority of clayey soil and clayey soil is established in the static pressure open mouths discrete element numerical model of pipe pile, realizes the continuous penetration process of static pressure pile. The distribution characteristics of jacking force, pile end resistance and pile side friction resistance along with penetration depth are discussed. The movement law of soil around the static pressure open closed pipe pile is compared and analyzed. The test results show that the size of the jacking force is related to the pile diameter, the larger the pile diameter, the greater the jacking force. The lateral friction of the pile is gradually exerted with the increase of penetration depth, and there is an obvious degradation effect. The variation range of the lateral friction of the open pipe pile is 50~ 100mm, and the soil plug height is about 3.5d. The numerical simulation results are compared with the laboratory test results, and the results are consistent. The research results can provide reference for the study of the penetration mechanism of opened and closed jacked pile.
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Research on Coupling Mechanism of Wireless Power Transfer of UAV with Strong Anti-offset and Lightweight

ZHENG Hongxing, ZUO Fei, WANG Cheng

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n the practical application of wireless power transmission technology in the field of UAVs, when the UAV lands due to the positioning accuracy and the control accuracy of docking there is error, will lead to inaccurate docking position and shift, due to the small size of the UAV, the size of the coupling mechanism will also be smaller, the offset at this time will lead to a decrease in the coupling degree of coupling mechanism, which in turn leads to the reduction of the efficiency of the wireless power transmission system, affecting the normal operation of the system. Therefore, in order to improve the anti-offset characteristics of the system, it is necessary to reasonably design and optimize the coupling mechanism of the UAV wireless charging system. In this paper, the coupling characteristics of different coupling mechanisms are analyzed and compared under the constraint of consistent line usage in combination with the structural characteristics of UAVs, and the optimal coupling mechanism suitable for UAVs is designed. Then, the parameters of the coupling mechanism are optimized for lightweight with M/l as the optimization goal. Finally, the feasibility of the coupling mechanism optimization method is verified by simulation and experiment.
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Research on lane change driving behavior based on highway scene

YANG Chonghui, ZHENG Ling, ZUO Yifang, WANG Kan, Zeng Jie, DING Xuecong

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In-depth study of human driver's driving behavior and habits has significant implications for promoting the anthropomorphism of decision-making in intelligent vehicles and improving driving safety. For the typical scenario of highways, effective feature parameters that characterize lane-changing driving behavior were extracted based on the NGSIM dataset. The correlation between lane-changing driving behavior and driving parameters was analyzed, and driving behavior characteristics were quantified. A GMM-HMM-based lane-changing intention recognition model was established. The research results show that the model has a high recognition accuracy. The recognition accuracy of lane-changing behavior 1 second before the lane-changing point reaches 95.6%. The accuracy of recognizing lane-changing intentions exceeds 80% when there is the intention to change lanes. The model can be applied to the anthropomorphic design of intelligent vehicle lane-changing strategies, effectively reducing lane-changing risks and improving driving safety.
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Equivalent electrochemical impedance thermal coupling model for lithium-ion batteries considering skin effect and high frequency additional heat generation

TANG Guofeng, ZHU Guangyao, HU Minghui, HU Jiamin, JIN Guoqing

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Establishing a reasonable equivalent electrochemical impedance-thermal coupling model is important for impedance calculation and temperature estimation during low temperature heating of batteries using high-frequency alternating current (AC). After using the NSGA-II algorithm to identify the parameters of seven different equivalent impedance models in the frequency range from 10 to 100000 Hz, it is found that the use of one resistor and inductor parallel module can more accurately describe the effect of skin effect on the impedance curve without increasing the computational effort compared to a single inductor module in high frequency region; after obtaining additional high-frequency heat generation at different frequencies and time-varying heat transfer coefficients with temperature using a topology that relies on the battery's own energy for heating, an electrochemical impedance-thermal coupling model applicable to the battery under high-frequency AC heating is proposed. The accuracy of the model is verified under constant frequency, and the necessity of using a time-varying heat transfer coefficient with temperature for temperature prediction is demonstrated; the practicality of the model is verified under variable frequency, and the maximum temperature error of prediction in the high frequency range is reduced from 2.93°C to 0.35°C with an RMSE of only 0.23°C compared with existing model.
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Study on chaotic characteristics of heterogeneous physical double pendulum

Kong Linghui, Liu Dingyang, Jian Kailin

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In order to solve the influence of materials with uneven mass distribution on the motion of double pendulum system in engineering practice, a heterogeneous double pendulum model was established based on the homogeneous physical double pendulum model, in which the position of the center of mass and the moment of inertia of the pendulum were extracted as variables. In order to further explore the chaotic characteristics of the system, the heterogeneous double pendulum system is approximated from Hamilton system to quasi-Hamilton system, and the dynamics equation of the double pendulum system is obtained by using Euler-Lagrange equation of the second kind. The energy threshold of Smale horseshoe chaos in quasi-Hamiltonian system is obtained by using Melnikov method with two degrees of freedom, which is used as chaos condition of Hamiltonian system. After programming with Matlab, the correctness of chaos condition is verified by numerical methods such as maximum Lyapunov exponential diagram, bifurcation diagram and Poincare section diagram, and the influence of each parameter on the system motion state and action mechanism are analyzed in detail. The results show that the chaos threshold of heterogeneous double pendulums depends on many factors, including the initial energy of the double pendulums, the position of the center of mass of the first pendulums and the ratio of moment of inertia of the two pendulums. With the different values of each parameter, the system will change from the regular motion state with chaos threshold to the irregular and complex motion state without chaos threshold. The reason why the system alternates between chaotic state and quasi-periodic state is explained and the correctness of theoretical prediction is proved. When the center of mass of the first pendulum, the mass ratio of the two pendulums and the ratio of moment of inertia of the two pendulums are set to the limit values, the reasons for the difference between the theoretical threshold and the actual numerical simulation results are found and explained. On this basis, the relationship between parameter values and the applicability of Melnikov method is further discussed, and the parameters under which Melnikov method is no longer applicable are discussed by numerical simulation classification.
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Effect of microplastics on soil phosphorus adsorption

Tang ZiChao, Tang Jin, Liang Luntao, Li Yanjun, JiangYanxue, Fang fang, Guo Jingsong

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As a new class of pollutants, microplastics have a large specific surface area and are easy to adsorb other pollutants. They are widely detected in soil and may affect the environmental behavior of phosphorus in soil. Phosphorus(P) plays an extremely important role in soil quality and nutrient cycling, and the loss of P from soil is also a major factor causing eutrophication of surrounding water. At present, there is no unified understanding of the effects of microplastics on soil P adsorption characteristics, and differences due to different content and particle size of microplastics is not clear. The mechanism of P adsorption in the microplastic-soil system formed after microplastics entering soil needs further study. In order to explore the effect and mechanism of microplastics on soil P adsorption, polystyrene microplastics (PS-MPs) were selected as microplastics samples, and soil from a farmland in Liaoning Province was sampled as the test soil. The P adsorption kinetics and adsorption isotherms of soil containing 0.1-10% microplastics were measured and analyzed. The effects of three different particle sizes of microplastics on soil P adsorption were investigated. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the crystal compositions and functional groups of the microplastic-soil system before and after adsorption, to explain the effect mechanism of microplastics on soil P adsorption. The results showed that the adsorption process of P in the microplastic-soil system could be divided into three stages. In the first stage of the adsorption process, the rate of liquid film diffusion stage was significantly increased (p<0.05), and consequently increased the adsorption rate of P in the microplastic-soil system. Compared with the soil without PS-MPs (qe=6.456mg/g), the concentrations of 0.1%, 0.5% and 1% PS-MPs significantly reduced the P adsorption capacity of the microplastic-soil system (p<0.05). However, the P adsorption capacity of microplastic-soil system increased significantly with the concentrations of 5% and 10% PS-MPs (p<0.05). In addition, the adsorption experiments using PS-MPs with size of 48, 150, and 250 μm showed that the microplastic-soil system containing 48 μm PS-MPs had the highest adsorption capacity for P, followed by 150μm PS-MPs and 250μm PS-MPs. The XRD and FT-IR patterns of the microplastic-soil system before and after adsorption were compared to reveal the mechanism of the influence of microplastics on soil P adsorption. Minerals containing Si, Al and Ca in the soil were the adsorption sites of P and microplastics. Microplastics reduced the adsorption of P in the microplastic-soil system by competing with phosphorus for adsorption sites. Since microplastics can also directly adsorb P, the adsorption capacity of microplastic-soil system would increase when PS-MPs were more than 5%. In addition, the decrease of particle size of microplastics in soil would reduce the inhibitory effect of low content PS-MPs on soil P adsorption, and enhance the promoting effect of high content PS-MPs on soil P adsorption. This was due to the increase in the total specific surface area of the microplastic-soil system when the particle size of microplastics decreased. Therefore, microplastics pollution in soil can significantly change soil P adsorption characteristics, which is closely related to the content and particle size of microplastics.
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Influences of frame flexibility on natural characteristics of dual-rotor wind turbine drivetrain

SHUAI Quan, ZHU Caichao, TAN Jianjun, WU Yaru, TAN Shuping, LAO Wenxin

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Dual-rotor wind turbine is a new type of horizontal axis wind turbine, which can use the wake of the front wind turbine to generate electricity and has a high utilization coefficient of wind energy. However, in order to reduce the flow field interference effect between the front and the rear wind turbine, the axial span of the transmission chain is longer than that of the single wind turbine, resulting in complex transmission chain modal characteristics and high potential resonance risk under the multi-point elastic support of the long-span flexible frame. In this paper, considering the frame flexibility and elastic support between the frame and the transmission chain, a rigid-flexible coupling dynamic model of the transmission chain of dual-rotor wind turbine was established, the coupling vibration mode of the transmission chain was analyzed, and the influence of frame flexibility on the inherent characteristics of the transmission chain was studied. The results show that the first two torsional vibration natural frequencies of the wind turbine transmission chain are 5.63Hz and 6.01Hz respectively, which correspond to the first torsional vibration natural frequencies of the rear and front wind turbine transmission chains respectively. There are three vibration modes in the drive chain of dual-rotor wind turbines, including the local vibration mode of the front or rear wind turbine drive chain, the coupled vibration mode of the front or rear wind turbine drive chain and the coupled vibration mode of the front and rear wind turbine drive chain. When the modal energy of each component of the system is mainly concentrated in the non-torsional direction, the frame flexibility will make the modal energy of each component transfer to the other components of the same side drive chain or the other side drive chain components.
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Theoretical characterization model of temperature-dependent tensile fracture strength of polymer matrix composites considering the effect of particle agglomeration

XU Chao, DONG Pan, WU Yuntao, WANG Ruzhuang, LI Ying, LI Weiguo

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The tensile fracture strength of polymer matrix composites at different temperatures have always been an important concern. As a common reinforcement phase, particles can significantly improve the tensile fracture strength of polymer matrix composites. However, with the increase of particle volume fraction, particles tend to agglomerate, which will affect the strengthening effect. For particle-reinforced polymer composites, considering the effects of particle agglomeration, as well as the evolution of the thermo-physical performance with temperature, a temperature-dependent analytical model for prediction of the tensile fracture strength of particle-reinforced polymer composites considering particle agglomeration was developed. The model predictions were in good agreement with the experimental data. The research results provide an effective way to quantitatively characterize the tensile fracture strength of composites with different particle content and temperature, and deepen the understanding of the influence of agglomeration phenomenon on the mechanical properties of composites at different temperatures.
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Cross-modal speech separation method by using multi-level feature fusion

Wenna Li, Kunpeng Wang, Hao Zhou, Juan Yao

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Greater accuracy and stability are achieved by applying the cross-modal speech separation method and the simultaneous use of audio-visual modal information, in contrast to those obtained through the use of single-modal methods. Most of the existing cross-modal speech separation methods are only applicable to scenarios with high-definition face images, may incur the risks of the intrusion of personal privacy and personal privacy disclosure. In light of this, we propose a multi-level feature fusion cross-modal speech separation method based on low-resolution images. Visual features are extracted by using this method that is meant for constructing a visual feature extractor for low-resolution images, with a three-branch structure of “fast-medium-slow” adopted. With each branch processing video frames at different rates, dynamic features of faces and lips at different levels are extracted. These features, corresponding to phoneme level, word level and discourse level features related to acoustic features, respectively, are fused in stages during feature extraction. To verify the effectiveness of the proposed method, we construct three types of experiments: the comparison made between the results obtained on the basis of different data sets and that achieved on the basis of audio-only method, the comparison made among the results obtained at different resolution levels on the basis of different data sets, and the model structure ablation experiments conducted on the basis of LRS3. The results show that, with the application of the proposed method, we can not only achieve speech separation on the basis of images of high resolution levels, but also obtain good separation performance on the basis of images of low resolution levels. On the basis of LRS3, LRS2, and GRID, the network achieves the improvement of 4.3%, 10.6%, and 26.5%, respectively, in terms of the SI-SNRi, and the improvement of 4.6%, 11.3%, and 21.8%, respectively, in terms of SDRi, compared with the results obtained by applying the unimodal speech separation model in the same conditions.
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Modal Significant consistency feature mining and multi-granularity feature enhancement for Visible-Infrared person re-identification

Xu Le, Li Fan, Li Huafeng

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Visible-Infrared person re-identification (VI-ReID) is a task of matching person in both visible and infrared modes. Although existing VI-ReID methods have achieved certain results, they have not effectively utilized the cross modality significant information and multi-granularity information of person. Therefore, this paper proposes a VI-ReID method for modal significant consistency feature mining and multi-granularity feature enhancement. Among them, the modal significant consistency feature mining improves the relationship weight selection method of cross attention mechanism, achieving effective extraction of modal significant consistency features; multi-granularity feature enhancement effectively utilizes the local discriminative information of person by extracting fine-grained features of person at different granularity. Compared with existing methods, the method proposed in this paper has achieved significant advantages on the public datasets SYSU-MM01 and RegDB. Experiments have shown that the effective utilization of cross modality significant information and multi-granularity information can enhance the cross modal robustness of features.
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Numerical simulation on walking of a tensegrity robot driven by the post-buckling of flexible rods

ZHANG Xing, JIAN Kailin, ZHANG Liang, HE Zigang

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Compared with traditional wheeled and footed robots, spherical tensegrity robots have the advantages of high strength to mass ratio, good cushioning performance and good terrain adaptability, and have a broad application prospect in deep space exploration. Cable driven mode is often used for tensegrity robots, however, the excessive number of actuators in the walking process brings difficulties to the manufacturing and controlling. A new driving mode based on the post-buckling deformation of flexible rods is proposed, and the numerical simulation of the walking process of the spherical tensegrity robot is realized, and the efficiency of cable driven and rod-post-buckling driven mode is compared. The exact solution of post-buckling deformation of a single bar is obtained by elliptic integral method. Based on this, the rigid-flexible coupling dynamics simulation model of spherical tensegrity robot is established in ADAMS considering post-buckling deformation of the bar, contact and friction. The walking gait of the spherical tensegrity robot is determined by the joint simulation of ADAMS and Simulink software using the Greedy Search algorithm. The control system model is established in Simulink software to realize the walking control of the robot to any target points under the post-buckling driven mode of rods. Compared with the conventional cable driven, with post-buckling driven mode, the number of actuators required for continuous robot walking is reduced from 18 to 6, and the walking speed is increased by 43.78%. The results of the study provide theoretical guidance for the design and manufacture of the new tensegrity robots.
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Modal analysis and structural parameter optimization of aviation elastic thin-walled casing

WU Anyang, SONG Chaosheng, ZHAO Shuaitao, DENG Zili

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In order to solve the resonance problem of an aviation elastic thin-walled casing, the finite element method was used to analyze the constrained modal under typical working conditions based on the elastic support stiffness of the aircraft frame. In this paper, the influence of structural parameters of aviation elastic thin-walled casing on the natural frequencies of constrained modal was studied. The results show that optimizing the position of constraint is the most effective way to change the natural frequencies greatly. When the natural frequency is at the edge of the resonance intervals, it can be adjusted slightly by optimizing the wall thickness and stiffener parameters. When the two constraint positions are located on the symmetry axis of the casing plane, the natural frequencies are minimum and decrease obviously with the decreasing of the constraint distance. With the increase of the thin-wall thickness, the 1st, 3rd, 5th and 6th modal frequencies decrease and the 2nd and 4th modal frequencies increase. The 1st and 3rd modal frequencies are almost not affected by the stiffener parameters. The 2nd, 4th modal frequencies increase with the increasing width and height of stiffener and decreasing stiffener aspect ratio. In addition, the 4th modal frequency increases with the increasing angle of stiffener. The 5th and 6th modal frequencies increase with increasing stiffener angle and decreasing stiffener width. On this basis, the structural parameters of the aviation elastic thin-walled casing were optimized to make the natural frequencies avoid the resonance intervals, thus improving the vibration resistance of the casing.
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A method for measuring the tensile elastic modulus of cross-ply composite plates based on S0 Lamb waves

Wang Yunlin, liu yaolu, Hu Ning

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In this paper, a method for measuring the elastic modulus of cross-ply composite plates based on Lamb waves is presented. Cross-ply composite plates are equivalent to Single-layer orthotropic plate with 9 independent elastic constants. The sensitivity of group velocity of S0 Lamb waves to elastic constants is studied in this paper. It is found that the group velocity of S0 Lamb waves is only related to the tensile elastic modulus and the in-plane Poisson’s ratio of the orthotropic plate at the low-dispersive frequency-thickness products range. By analyzing the change ranges of equivalent engineering elastic constants for cross-ply composite plates, it is discovered that the change of in-plane Poisson’s ratio of cross-ply composite plates is small enough to ignore its effect on the group velocity of S0 Lamb waves. Therefore, the group velocity of S0 Lamb waves can be used to estimate the tensile elastic modulus of the cross-ply composite plates, and the mapping relationship between the group velocity of S0 Lamb waves and the tensile elastic modulus can be established. The method has been verified by numerical simulation and experiment and the error between the tensile modulus and the actual value of the composite plate obtained by this method isless than 10%, which provides convenience for the measurement of relevant structural parameters in aerospace and other industrial fields.
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FFT acceleration algorithm for contact problems based on triangular element discretization

CHEN Nan, ZHU Kai, JIANG Zhizhen, GONG Shiyu, LI Pu, JIN Xiaoqing

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Effectively solving the governing equations for contact problems often involves complex mathematical theory, while the distribution of contact stress is highly random in practical engineering applications. In this study, a novel algorithm is proposed based on the triangular load discrete element and the Discrete Convolution Fast Fourier Transform (DC-FFT) algorithm. This algorithm provides a high-precision and reliable method for efficiently solving the contact response of a solid under any load distribution. Compared to the commonly used uniform load element discrete method, the analytical solution of the triangular element is more complex, but it better simulates the characteristics of contact load distribution and accounts for situations where the load at the contact edge increases from zero or decreases to zero. The stress component under the action of the triangular and uniform load elements is derived based on the "excitation-response" characteristics of the contact influence coefficient matrix to optimize the solution method of the triangular load discrete element. By constructing the stress solution in the form of a discrete convolution including the influence coefficient matrix, the stress superposition effect of a target node under the action of all elements can be further simplified and accelerated by using the DC-FFT algorithm for highly repetitive matrix calculations. Programming and calculation analysis show that the proposed algorithm based on the triangular load element is accurate and efficient.
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The effects of water fluctuation on typical estrogens and activities in the water level fluctuation zone of the Three Gorges Reservoir

Zhou Min, Shao Ying, Huang Siyu, Chen Zhongli

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[Objectives] In the current study, the water level fluctuation zone of the Three Gorges Reservoir (TGR) was selected, in which chemical analysis was combined with biological testing to investigate the effects of water fluctuation on the compounds and concentrations of estrogenic effector substances and the estrogenic activity in soil (non-flooding period) and sediment (flooding period). The correlation between typical estrogens and estrogenic activity was analyzed. The study hence could provide important data support for reservoir ecological safety and environmental health management. [Methods] The distribution and concentration of 8 typical estrogens were analyzed by an ultra-performance liquid chromatography-mass spectrometry (UPLC-MS), and the estrogenic activity was determined by a Yeast Estrogen Screening assay (YES). Correlation analysis and concentration summation calculations were used to establish the correlations between chemical substances and biological effects. [Results] Only estrone (E1) and ethinylestradiol (EE2) were detected with the ranges of 0.02-2.67 ng/g from the 8 studied estrogens. The sediments of the flooding period showed significantly estrogenic activity, which the 17β-estradiol equivalents (EEQ) ranging from 0.637-6.987 ng EEQ/g. Correlation analysis did not show distinctly correlation between the target compounds and estrogenic effects, which the detected chemicals only contributed about 29.46% of the estrogenic activity. [Conclusions] Water fluctuation could affect the type and concentration of estrogens in the water level fluctuation zone of the TGR, with the estrogenic activity increased during flooding period. The linkage between typical estrogens and estrogenic activity was not found. Therefore, new methods and techniques are required in order to increase the identification accuracy and improve the management on the risk of estrogenic effects in the water level fluctuation zone.
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Dynamic Performance Optimization Method of Buck-WPT System Based on Controllable Inductor

LING Rongguang, HE Leijie, Liu Qiao, YE Jiaqing, MENG Fanchao, TANG Chunsen

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The SS Buck-WPT system composed with Buck and basic SS-type wireless power transfer circuit has been widely used in inductive wireless power transmission because of its superiority in structure, control methods and effect. However, this kind of system can"t meet the requirements of time-varying system in responsiveness due to its poor dynamic characteristics. For example, the system in filed applications has large overshoot and oscillation when starting up, alteration on system stability for the various load resistance and sharp fluctuation of primary resonance current under light condition. To address those dynamic problem, a SS-type Buck-WPT system based on controllable inductance was proposed in this paper. First of all, controllable inductance was analyzed in detail to figure out the principle of adjustable inductance and modeled in COMSOL to verify the conclusion. Then the Mathematical modeling analysis of SS Buck-WPT system was carried out. Taking SS WPT system as the load of Buck, the system state space equation was derived. And the system was described with two-dimensional phase trajectories by reducing dimensionality. Then the phase trajectory operation law during start-up was proposed and pre-Buck circuit was improved by changing conventional inductor to controllable one and controlling the inductor via to make system get in stable in one turn-on without any overshoot; The output voltage will be different that goes back and forth once load changes. So, the PI algorithm is used to keep current constant, so that the phase trajectory runs as expected, and the output of secondary returns to the steady state quickly with the real-time control of inductance ; For the excessive primary resonant current, the controlled inductance cascaded with SS in primary to maintain it’s current within permissible values by adjust inductance automatically. To validate the performance of proposed method, the prototype is set up in Simulink. The results show that this strategy has better effect on system dynamic performance and loads tolerance compared with traditional one.
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A novel Red-Black Coloring parallel projection algorithm for two-phase flow using the phase field method

WANG Xiaoshuang, ZHANG Liangqi, XIAO Yao, ZENG Zhong

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In this study, an interleaved parallel finite volume projection algorithm is proposed to solve the two-phase flow control equations based on the phase field method. This strategy relies on the explicit advancement of the pressure Poisson equation, thus breaking through the efficiency bottleneck of the projection algorithm for solving the incompressible Navier-Stokes equations. Moreover, we propose an interleaved scanning strategy to update variables on nodes for compact spatiotemporal coupling. The combination with the phase field method enables accurate capture of interface dynamics and topology at a lower cost. Test results show that with 131072 grids and 8-thread CPU parallelization, the efficiency of the proposed parallel algorithm reaches more than 80 times that of the serial standard projection algorithm.
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Design and Development of Large-amplitude Ultrasonic Vibration assisted High-speed Dry Cutting Equipment and Its Performance Test

HUANG Xuefeng, CAO Huajun, ZHANG Jin, SONG Yang, KANG Xinzhen

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Ultrasonic transducer is the core component of ultrasonic vibration assisted cutting device, in order to develop a large-amplitude ultrasonic vibration assisted cutting device suitable for high-speed dry cutting, it is necessary to design and develop the ultrasonic transducer initially. First of all, based on the design method of the second-stage amplified ultrasonic transducer considering the tool, following the integrated design concept of amplifier-ultrasonic transducer, combined with the results of modal analysis and harmonious response analysis of ANSYS finite element software, the two-stage amplified ultrasonic transducer was designed and developed. According to the characteristics of the developed two-stage amplified ultrasonic transducer, the matching ultrasonic generator, anti-rotation ring, power transmission system and tool holder shell structure were designed and developed systematically. Secondly, the performance tests of impedance analysis and amplitude measurement were carried out for the developed two-stage amplified ultrasonic transducer. Finally, the experimental test and analysis of the designed and developed large-amplitude ultrasonic vibration assisted high-speed dry cutting device were carried out to explore the improvement of the surface quality of the difficult-to-machine material 30CrMnSiNi2A. The results show that the longitudinal ultrasonic vibration simulation results of the designed and developed two-stage amplified ultrasonic transducer are consistent with the theoretical design, and the longitudinal vibration amplitude output is stable. Besides, the longitudinal vibration amplitude is 15.4 μm at 50 % output power and can maximum reach 25.1 μm, and the output amplitude is positively correlated with the power percentage which means that the performance test is good. The developed large-amplitude ultrasonic vibration assisted cutting device can greatly reduce the cutting force and surface roughness in the feeding direction, significantly improve the surface quality of difficult-to-machine materials, and is suitable for high-speed dry cutting of difficult-to-machine materials.
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Dynamic Characteristics of the Mechanical Antenna Based on Vibrating Permanent Magnet

ZHANG MIAO, WANG JISHUO, NING HUIMING, HUANG KAIYAN, YUAN WEIFENG

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In the traditional wireless communication field, the application of long wave communication is limited in small and medium-sized platforms because it requires large size signal transmitting antennae. Based on the inverse piezoelectric effect, vibration theory, and Maxwell's equations, a three-degree-of-freedom cut-out beam structure of the vibration permanent magnet type mechanical antenna prototype was proposed, established its electric-mechanical-electromagnetic energy theory model and developed the mechanical antenna prototype, studied the radiation influence factors of the mechanical antenna and its frequency modulation technique. The experimental results proved that the electromagnetic wave signals can be frequency-modulated by exciting the different vibration modes of the mechanical antenna prototype, which provided novel ideas from theoretical and technical perspectives for communication of low-band signals.
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Effect of PDA/Fe₃O₄ sizing agent on mechanical properties of thermoplastic carbon fiber/polyamide 6 composites

HUANG Tao, Wu Xiaopeng, NING Huiming, Hu Ning

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In carbon fiber reinforced thermoplastic composites (CFRTP), the strength of the interface between the carbon fiber (CF) and the thermoplastic resin matrix has a tremendous impact on its overall mechanical properties. In order to improve the interface between carbon fiber (CF) and polyamide 6 (PA6), nano-sized Fe3O4 was introduced to the CF surface for synergistic modification by using the polymerization and adhesion characteristics of dopamine (DA). Through simple immersion co-deposition, the poly-dopamine/nano-Fe3O4 coating was constructed on the CF surface by oxidative self-polymerization of DA. The microstructure and chemical characteristics of CF surface before and after modification were characterized. The results showed that adding PDA/Fe3O4 sizing agent could significantly improve the roughness and chemical activity of CF surface, and strengthen the mechanical engagement and chemical interaction between fiber and resin matrix. Compared with unmodified CF/PA6 composites, the prepared modified CF/PA6 composites showed excellent mechanical properties, and their bending strength and interlaminar shear strength increased by 30.8% and 29.1%.
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Multi-Criterion Flexible Job Shop Scheduling Considering Group Maintenance Method

li liwei, denglei, Liao wenzhu, Tang baoping, Wang yi

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Abstract: The society’s demand for individualized, small batch and customized products can be satisfied by the flexible job shop system, this workshop system has numerous equipment, complex process paths, and various failure frequencies. However, the single machine preventive maintenance approach is now mainly employed to avoid equipment breakdowns, which is certain to raise the number of maintenance, maintenance costs, and have the negative impact on production operations. To address the problems caused by the traditional single machine preventive maintenance, the group preventive maintenance approach is proposed to apply in the flexible job shop system, and the joint mathematic model of group preventive maintenance and multi-criterion flexible job shop scheduling is established. In order to overcome the problem of insufficient local search ability of traditional algorithms, a new multi-criterion evolutionary algorithm is designed to solve the multi-objective flexible job shop scheduling problem, and to show how to apply the group preventive maintenance strategy in the flexible job shop system. The experimental results show that the designed multi-evolutionary algorithm can obtain more optimal solutions, has faster convergence speed, and can converge to better optimal solutions; compared with the single preventive maintenance method, the group preventive maintenance has fewer maintenance times, lower maintenance costs, and less impact on production activities, the example result show that the group preventive maintenance time and maintenance cost by 150% compared with the single preventive maintenance; and propose the group preventive maintenance approach can be used for the maintenance of production equipment in semiconductor foundries in the future.
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Froth flotation purity prediction based on Wasserstein GAN data augmentation

WU Haosheng, JIANG Pei, WANG Zuoxue, YANG Bodong

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In mineral processing industry, accurately predicting concentrate grade can help engineers adjust process parameters in advance and improve flotation performance. However, the prediction accuracy of concentrate grade has been restricted by limited sample sizes, high-dimensional data and complex temporal correlations in actual mineral processing. A time-series data generation model called LS-WGAN is proposed according to the problem of prediction for small sample data, which combines wasserstein generative adversarial network (Wasserstein GAN) and long short-term memory (LSTM) neural network. LSTM network is mainly used to capture the time correlation in mineral processing data, then Wasserstein GAN is used to generate samples similar to the original data distribution for data augmentation. In order to improve concentrate grade prediction accuracy, a mineral processing prediction model called C-LSTM is established, the prediction accuracy of the proposed method is verified by experiments based on real froth flotation process data.
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Research on Power and Data Parallel Transmission Technology Via a Dual-channel for WPT System

JIAN Zhijun, ZHANG YuLin, MENG Wei, JIA Yahui

Abstract: (234) HTML (0) PDF (0.00 ByteKB) (0)

To solve the problem of power and data parallel transmission simultaneously in wireless power transfer system for rotating mechanism, a parallel transmission method of power and signal based on dual-channel mode was proposed. On the basis of analyzing the power and signal transmission mechanism in dual-channel mode, a mutually decoupled power and signal transmission coil is designed. The power transmission is based on the induction coupling technology of SN topology, and the signal transmission is based on the amplitude modulation mode, combined with the envelope demodulation technology, realizing the two-way signal transmission. Experimental results verify the effectiveness of the proposed method, the power signal transmission channels do not interfere with each other, and the signal transmission error rate is zero.
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Multi-scale characterization of coal pore and fractures and its influence on permeability—Taking 14 large coal bases in China as examples

WANG Gang, CHEN Xue-chang, CHENG Wei-min, CHEN Hao

Abstract: (839) HTML (0) PDF (0.00 ByteKB) (0)

In order to explore the characteristics of pore and fractures at different scales and their influence on permeability, nitrogen adsorption, mercury injection and CT experiments were carried out on 14 large coal bases in China, and conducted seepage experiments on the coal samples after CT scanning. The results showed that the micropores and transition pores in each coal sample are mostly closed pores with poor connectivity, which is not conducive to the seepage of coal. The pore and fractures volume of r=10nm and r=100μm accounts for a large proportion, which contributes most of the porosity of coal. The large-scale parallel plate pores in S2 and S3 provide sufficient space for seepage. By dividing dominant pore size segments characterized by three experiments, a method for comprehensively characterizing porosity and fractal dimension is proposed. The porosity range of each coal sample is 1.62-11.60%, and the fractal dimension range is 2.29-2.78. The permeability of coal samples is between 0.0002-0.6525×10-15m2, mainly in medium and low permeability. The relationship between the porosity components of r<50nm, 50nm8.5μm and permeability is y=0.2741x-0.0781, y=0.0674x+0.0237 and y=0.0039x2.5986, respectively. The correlation between the porosity component of r>8.5μm and permeability is the strongest. Compared with nitrogen adsorption and mercury intrusion experiments, CT experiment is more suitable for analyzing the influence of pore and fractures on water seepage.
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Critical transition relations for fatigue failure of PEEK gear under oil injection lubrication

Abstract: (2051) HTML (0) PDF (0.00 ByteKB) (0)

Polyetheretherketone (PEEK) gears are high-performance polymer gears that are widely used in automobiles, drones, robots, and other fields. However, the complex failure mechanism of PEEK gear and the failure forms change with load lead to a shortage of a reasonable design basis in power transmission applications. Aiming at the unclear failure mechanism and transition of failure forms of PEEK gear, carried out the fatigue performance test of PEEK helical gear pair under oil injection lubrication, and calculated the contact stress and bending stress of PEEK gear, together with analyzing the failure by scanning electron microscopy and other equipment. Experimental results that the failure forms of PEEK gear under oil injection lubrication are mainly tooth surface pitting failure and tooth root fatigue fracture, discussing the failure mechanism of PEEK gear tooth surface pitting and tooth root fatigue fracture under oil injection lubrication. Simultaneously, discovering the critical transition relationship between PEEK gear contact fatigue failure and bending fatigue failure, and proposed an evaluation method for the failure form of PEEK gear. When the ratio of contact stress to bending stress of PEEK gear is lower than 1.02, PEEK gear mainly suffers from root fatigue fracture; when the ratio of contact stress to bending stress is higher than 1.1, PEEK gear mainly suffers tooth surface pitting failure; and when the ratio of PEEK gear contact stress to bending stress is between 1.02-1.1, there is a critical failure transition point between tooth surface contact fatigue and root bending fatigue.
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Bridge apparent disease detection based on improved YOLOv5s

DONG Shaojiang, TAN Hao, LIU Chao, HU Xiaolin

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To solve the problems of low accuracy, high false detection rate and missed detection rate of current target detection methods in concrete bridge apparent disease detection, an improved YOLOv5s method on bridge apparent disease detection is proposed. Firstly, to achieve more effective fusion of features at different scales and increase receptive fields, an improved spatial pyramid pooling module is added to YOLOv5s network to enhance feature extraction capability and reduce computational cost. In addition, aiming at the problem of high false detection rate and missed detection rate caused by cross distribution of different defect features in disease images, a light attention module is added in YOLOv5s network. At last, the loss function considering vector angle is adopted to solve the problems caused by the different size of bridge defect, classification difficulty and small data set leading to the boundary box regression mismatch. Experimental results show that the improved YOLOv5s detector can effectively improve the accuracy, reduce the false detection rate and loss detection rate in bridge apparent disease detection task.
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Impact of violence injection attack on power system state estimation

qin fan

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With the continuous development of society and the continuous progress of information technology, people's demand for electric energy is increasing. At the same time, with the vigorous promotion of renewable energy in various countries, the growth of power scale has been further strengthened. The traditional power system can no longer meet the needs of today's power industry, and the concept of smart grid has been put forward. Previous studies have shown that attackers can launch injection attacks on smart grid power system, thus affecting the normal operation of power system state estimation. This paper presents a random number based violence injection attack method without power system topology information. The influence of the proposed attack method on the state estimation of smart grid power system is studied in the state estimation based on weighted least squares and Kalman filter. The simulation experiment is carried out on the ieee-14bus simulation system to simulate the attacker's attack on the power system, and two different state estimates are analyzed and discussed.
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Research on high-power and high-efficiency WPT system technology based on LCC-S

wangjihua, wugang, lejingli, yuanwenjie

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Wireless power transfer technology provides an effective way for the problem of near-shore energy transmission of ships. This paper proposes a design method for high-power and high-efficiency wireless power transmission, and analyzes the loss of the wireless power transmission system with LCC-S topology. further analyze the relationship between the system efficiency and the primary inductance, select the parameters of the optimal efficiency point, design the coupling mechanism of the magnetic integration mode, and carry out the circuit simulation of the system. An experimental platform is built, and the experimental results verify the effectiveness of the proposed method. The output power of the system reaches 93kW and the efficiency reaches 96%.
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Study on End Slope Mining Technology of Top Coal Seam in Baorixile Open-pit Mine

LIU Guangwei, ZHANG Jing, BAI Runcai, LI Hongyi, WANG Qiang

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At present, there are still some limitations in the process of mining and construction of the end slope of the near-horizontal composite coal seam open-pit mine. Only the mining of the lower coal seam is studied, and the mining of the top coal seam is more difficult and less studied. Therefore, in order to carry out the mining of the top coal seam in the near-horizontal composite coal seam, the author analyzes the engineering geological condi-tions and strata occurrence characteristics of the slope of the Baorixile open-pit mine, and uses FLAC3D to con-struct the three-dimensional numerical simulation model of the end slope, and calculates the relationship between the filling step distance and the slope stability when the top coal seam 1-2 is mined with the help of the inner dump plate. The slope stability control technology and corresponding mining scheme of 1-2 coal seam in top coal seam are determined. The research results show that the replacement step distance of the top-level coal seam in the end-slope 1-2 coal seam is not more than 80 m. When the top-level coal seam in the end-slope 1-2 coal seam is mined, the equipment is arranged on the flat plate of the inner dump developed to the bottom plate of the 1-2 coal seam. The mining method is layered tamping and inner row tracking backfilling. The whole region can recover 1-2 coal 22.6 million t by end slope mining, and obtain income of 4.972 billion yuan.
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Inspection of Image fog Concentration Consisting of Regression-Fitting NR Function and GPDR Prior

wen li min, wang hui feng, ju yong feng

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Concerning the shortcoming of fog-concentration inspection in the field of image defogging, a scatterplot prior of generalized pixel difference-ratio (GPDR) was proposed and Naka-Rushton fitting function was introduced to inspect the fog concentration. Firstly, the gray scatterplots were built under standard foggy image sets with different scenes so as to extract the prior of GPDR, and the correctness of gray difference-ratio prior was verified based on the degradation model of visual field image. Secondly, the Naka-Rushton fitting function was set up according to constraint prior, and the parameter (n,k) of standard image sets from fitting NR function were calculated, and a lookup table of (n,k) corresponding to the fog concentration in the field of view were established. Thirdly, regression analysis was used to calculate the fitting parameter (n",k") of scatter plot of real foggy image, and the comprehensive correlation coefficient between the parameter (n,k) of the standard image sets and the parameter (n",k") of real image sets were calculated, and the parameter (n,k) whose correlation coefficient exceeded the threshold through searching the lookup table were concerned as the level valuation of concentration inspection. Simulations show that result of this algorithm is in line with the concentration change trend by test for fog image with different concentrations, and simulations also show that correlation coefficients between the results of this paper with PM2.5 can be up to 0.95 by test of samples with different concentrations both in the same scenes and in different scenes. This shows that the algorithm can be used as the fog concentration rating for visual field, and the horizontal comparison test shows that inspection accuracy of the algorithm in this paper can be up to 4.8%.
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Research on Magnetic Integration of Coupling Mechanism of UAV with Multi-degree of Freedom

CHEN Shaonan, ZHAN Zhen, XIAO Jing, GONG Wenlan, WU Xiaorui, WU Ning

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The UAV wireless charging system adopts the DD type transmitting coil to effectively reduce the magnetic leakage, but only generates a horizontal magnetic field in one direction, which requires high docking accuracy of the UAV, low degree of freedom, and complicated control. This paper proposes a magnetic integrated design scheme for the transmitter. The transmitter coil is composed of two sets of DD coils on the top and bottom and left and right to generate magnetic fields in both X and Y directions. The compensation coil is wound into a unipolar square in the middle to achieve Decoupling and integrated design. First, the reliability of the magnetic integrated design is verified based on the COMSOL simulation software. The simulation proves that the designed transmitter can provide power for multiple coupling mechanisms with multiple degrees of freedom. Secondly, the output characteristics of the system are designed and analyzed. Finally, an unmanned aerial vehicle wireless charging system was built for verification. The results show that the designed system can provide multi-degree-of-freedom power supply for horizontal solenoid-type coils and vertical square coils.
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On-line detection method of cigarette case chromatic aberration based on k-means clustering

Li Yinhao, Li Ying, Wang Kaibin, He Zifen

Abstract: (146) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the problem that the online detection of chromatic aberration of small box cigarette case on the quality inspection machine is slow, an online detection method of cigarette label chromatic aberration based on k-means clustering is proposed. Based on image processing and machine vision, this method identifies the standard sample collected by the CCD camera and the main background color of the cigarette scale to be detected, and then converts through the color space, and finally performs the detection of chromatic aberration, and the chromatic aberration is less than 4.0 for the qualified cigarette case. Experimental results show that because there is no need for background removal and image registration, the detection speed of this method is better than that of other algorithms, and the accuracy can meet the actual production needs.
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Kernel recursive least squares with the nearest PRQ Nystr?m method

Liu Qiang, Wang Shiyuan, Wang Daili, Qi Letian

Abstract: (213) HTML (0) PDF (0.00 ByteKB) (0)

The development of the kernel recursive least squares (KRLS) algorithm, popular with the fastest convergence rate and best filtering accuracy in kernel adaptive filters (KAFs), is limited by the linear growing structure and enormous computational complexity. To alleviate these issues, KRLS with the Nystr?m method (NysKRLS) based on probability density rank-based quantization sampling (NysKRLS-PRQ) has been proposed to alleviate the complexity of KRLS at the cost of decreasing accuracy. To further improve the accuracy of NysKRLS-PRQ, we propose KRLS with nearest PRQ Nystr?m method (NNKRLS-PRQ) algorithm was proposed. The input vectors of NNKRLS-PRQ in the feature space are organized by p disjoint clusters. According to the distribution situation of input vectors and the confidence probability of the Gaussian kernel, NNKRLS-PRQ adaptively chooses proper samples selected from the corresponding cluster to project the input vector. The simulations prove the superiorities of NKMNKRLS.
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Energy evolution of hexagonal honeycomb under different graded cyclic loading and unloading modes

Zou Quanle, Zhou Xiaoli, Wang Ruizhi, Liu Hao, Liu Ying

Abstract: (167) HTML (0) PDF (0.00 ByteKB) (0)

In order to elucidate the influence of cyclic loading and unloading paths on the energy evolution of hexagonal honeycomb, three different graded cyclic loading and unloading tests were designed, and the evolution characteristics and interrelationships of total external input energy, elastic deformation energy, dissipation energy and plastic deformation energy under different graded cyclic loading and unloading modes were revealed. The results show that the initial peak strength and platform stress of the honeycomb are related to the elastic energy release during the unloading process. Total external input energy, elastic deformation energy and plastic deformation energy of the honeycomb show a nonlinear increase with the increase of the number of unloading levels. However, the dissipation energy decreases with the number of unloading levels in the first three cycles, and the upper limit of the cycle load is larger in the last stage. The disturbance effect is stronger than the enhancement effect, and the dissipation energy shows an opposite trend. When the upper limit of the cyclic load is raised, the damage inside the honeycomb increases, and the closer to the initial peak strength of the honeycomb, the more serious the damage is. Besides, when the lower limit of the cyclic load is raised, less elastic energy is released, and the damage is intensified. The research achievements could be beneficial to revealing the damage and instability mechanism of honeycomb under different stress paths, and lays the theoretical foundation for honeycomb applications in mines and underground spaces.
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Analysis on the Quantity Configuration and Combination of the Resource Equipment of the Plane Mobile Stereo Garage Based on Semi-Open Queueing Network

Li Jianguo, Ma Shangpeng, ChangLidan

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In order to improve the operation efficiency of stereo garage, the equipment configuration of planar mobile stereo garage under different access task arrival rates was studied. The planar mobile stereo garage was modeled as a semi-open queueing network model. According to the different access vehicle locations of the stereo garage, 10 kinds of access vehicle process operation scenarios were analyzed. The evaluation indexes of the stereo garage were defined as the service time of customer access vehicle and the operation energy consumption of access vehicle process equipment. The semi-open queueing network model of planar mobile stereo garage is optimized and solved from the perspectives of customer satisfaction and garage operator, through the simulation analysis under different customer arrival rate, each handling equipment and elevator configuration combinations on customers in the system access vehicle service time and the impact of energy consumption, the simulation results show that: The analysis of the stereo garage resource configuration combination can effectively improve the system operation efficiency under different arrival rates, and provide decision support for the optimal design of the system, improve the utilization rate of equipment, and save the systematic operation cost.
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Propagation and reflection of stress wave about primary and secondary waves in rectangular plates

李, LIU zhanfang

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The modified theory of elastic stress waves states that the wave equations on volume strain are consistent with existing theories, but a set of weakly coupled wave equations on volume strain and partial strain has been developed. Aiming at the fluctuation problem of stress wave under the impact of concentrated load on rectangular plate, two sets of control equations for stress wave propagation and the fluctuation boundary conditions of loading surface and free surface are established. The finite difference method is used to solve the wave equation, and the stress wave is simulated numerically for the propagation of the main and secondary waves and the reflection process of oblique incident waves on the free plane. The partial strain splits into two parts during propagation, one part propagates together with the volume strain to form the main wave, and the other part propagates slower to form a secondary wave. The numerical simulation results show that the propagation image of the stress waves in the nanocalcium glass plate under shock load is completely consistent.
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Research on UAV wireless charging identity authentication method based on inverse modulation

Xiaorui WU, Shaung WANG, Shaonan CHEN, Jing XIAO, Wenlan GONG, Ning WU

Abstract: (225) HTML (0) PDF (0.00 ByteKB) (0)

Wireless charging technology is more and more widely used in UAV, home appliances, electric vehicles and other fields because of its flexibility, reliability and safety. In order to achieve the optimal energy efficiency and condition monitoring of the system and improve the performance of the wireless charging system, the identity authentication and communication connection between the UAV and the charging end need to be carried out before wireless charging to ensure the normal operation of the charging process. Because the traditional communication mode has the problem of chaotic connection in the communication connection of multi UAV wireless charging system, resulting in the disorder of the charging system, it is necessary to authenticate the ID information between the charging end and the UAV before charging the UAV, complete the communication connection between the UAV and the charging end, ensure that the charging end and the UAV are charged after establishing the communication connection, and ensure the normal charging process. In order to solve the problem of chaotic communication of multi UAV wireless charging system, this paper proposes a method of multi UAV wireless charging identity authentication based on the method of inverse modulation. Based on the original UAV wireless charging system, before wireless charging, the driving signal of the inverter circuit is used as the carrier to modulate the unique ID information of the charging end and generate the electric energy signal carrying the ID information of the charging end, After receiving the electric energy signal, the UAV identifies the ID of the charging end for communication pairing, and then the inverter circuit works at a fixed frequency of energy transmission to wirelessly charge the UAV. This method carries out identification through the UAV wireless charging system itself, without adding additional hardware circuit and signal transmission coil, and simplifies the system structure and cost.
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Efficiency and mechanism of Cu-FeOx@AC activated peroxymonosulfate system for algae removal

CHEN Hao-tian, XIANG Ping, JIANG Wen-chao, LI Yu-ping, ZHOU Yuan, WANG Kai

Abstract: (198) HTML (0) PDF (0.00 ByteKB) (0)

The Cu-FeOx@AC composite catalyst, recyclable Cu-Fe bimetallic oxides, was prepared to explore the new algal treatment technology in eutrophic water. Hydrothermal method and high-temperature calcination method were used to make Cu-FeOx loaded on the surface of granular activated carbon. Then, the composite catalyst was characterized by XRD, SEM, FTIR and XPS. At the same time, the effects of Cu-FeOx loading ratio to AC, amount of PMS, initial pH and different reaction systems on algae removal were studied, and the effects of Cu-FeOx@AC activated PMS system on algae removal were studied. Free radical shielding experiments and XPS analysis were carried out to explore the reaction mechanism of Cu-FeOx@AC activated PMS system. The experimental results showed that when the initial pH is 6, the initial algae concentration is 1.4×109 L-1, the catalyst dosage is 0.2 g·L-1, and the PMS dosage is 0.5 g·L-1, the degradation rate of algae can reach 97.25% in 90 min. In this reaction system, algal cells can be adsorbed on the face of Cu-FeOx@AC. Under the valence conversion between the Fe and Cu, and the synergistic reaction of AC, the holes, 〖"·O" 〗_"2" ^"-" , "·OH" ,〖" SO" 〗_"4" ^"·-" and singlet oxygen could be produced by composite catalyst, to remove the algal cells.
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Coffee recognition method based on improved convolutional neural network

LIANG Jianyu, LUO Dehan, LIU Qi, LI Jiachang

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Coffee flavor is one of the main factors consumers consider when tasting and choosing coffee. Traditional and common methods of assessing coffee aroma are based on expensive equipment or artificial senses. These methods are time-consuming, costly, and require trained evaluators. Therefore, we propose a low-cost and portable coffee recognition method that combines an improved convolutional neural network (CNN) to recognize and classify five different varieties of coffee. The coffee smell is collected through the electronic nose, and an improved CNN classification model with three convolution layers was designed using Leaky-ReLU and Dropout model optimization techniques, which has improved performance compared to commonly used CNN models. Compared with other models used for machine olfaction, the experimental results show that the accuracy of improved CNN model for coffee five classification can reach 84.80%, and the model can effectively classify coffee.
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Electrochemistry and Persulfate Synergistic Action to Remove Fulvic Acid from Leachate

YU Zhi-peng, WANG Yi-qian, ZENG Xiao-lan

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The ‘membraneSbioreactor (MBR) + reverse osmosis’ technology is usually applied to treat leachate from most incineration plants in China. Studies have showed that the high fulvic acid concentration in reverse osmosis system influent results in the fouling of membrane. The persulfate synergistic electrochemical system(EC+PS system) was used to reduce fulvic acid concentration. The main active substances for removing fulvic acid in the system were discussed. The effect of initial pH value, persulfate dosage(PS), current density, plate space, NaCl concentration on the degradation of fulvic acid was investigated. The results showed that the removal of fulvic acid was mainly depended on Cl_^- provided by HClO,.OH and SO₄_^-_^.in turn. The fulvic acid removal rate decreased slightly with the increase of initial pH and plate spacing,Sincreased firstly and then decreased with the increase of initial PS concentration,Sfirst increased and then remained unchanged with the increase of current density, decreased slightly with the increase of Cl- concentration The current density and persulfate dosage were the main influencing factors for fulvic acid removal . The leachate effluent of MBR from actual incinerator was treated by EC+PS system under the current density 30mA/cm_², potassium persulfate 9g/L and reaction time 6h. The three-dimensional fluorescence spectrum results showed that the removal rate of fulvic acid in visible and ultraviolet regions reached 98.65% and 97.80%, respectively, and the EC+PS system could effectively remove fulvic acid in actual wastewater
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Migration of dissolved organic matter in an ice-water-sediment system under freeze-thaw alternating conditions

YANG Li, CHEN Zhong-li, SHAO Ying, WU Si-qi

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Objectives: At present, the research on the freezing of surface water mainly focuses on the distribution characteristics of heavy metals and nutrients in ice-water systems during the freezing period. The indoor simulation experiments focus on the migration and influencing factors of pollutants in ice-water systems during freeze-thaw process. However, the migration of pollutants in ice-water-sediment systems under freeze-thaw alternating conditions remain unclear. In the current study, the dissolved organic matter (DOM) was selected as the study object to explore the distribution and migration of dissolved pollutants in an ice-water-sediment system. Combined with total nitrogen (TN), total phosphorus (TP) and other indicators, the correlation characteristics of different substances in freeze-thaw process were analyzed. In addition, environmental estrogens were chosen as represented microorganic pollutants to illustrate the variation on concentrations between ice and water phase during the freeze-thaw alternating process. Methods: Indoor control experiments were set up to measure the three-dimensional fluorescence spectra (EEMs), specific ultraviolet absorbance (SUVA254), and concentrations of total nitrogen (TN), total phosphorus (TP) and dissolved organic carbon (DOC) in ice and water during freeze-thaw process, and the correlation analysis among three-dimensional fluorescence characteristic index, SUVA254, TN, TP and DOC was performed. Simultaneously, the concentrations of bisphenol A (BPA), estradiol (E2) and ethinyl estradiol (EE2) in an ice-water system during freeze-thaw process were measured. Results: 1) The fluorescence intensity peaks of tryptophan-like, tyrosine-like and humic acid-like compounds in the three-dimensional fluorescence spectrum of aqueous phase increased during freezing process, and the concentrations of TN and TP increased to 1.47 and 1.13 times of the raw water sample. The results indicated that tryptophan-like, tyrosine-like and humic acid-like dissolved organic matters, TN and TP migrated from ice phase to aqueous phase due to the freeze concentration effect. When the water was completely frozen, the fluorescence intensity peaks of tryptophan-like, tyrosine-like and humic acid-like compounds at ice phase was lower than that of the raw water sample, and the concentrations of TN and TP were reduced to 0.76 and 0.87 times as compared to the raw water sample, which indicates that those three kinds of dissolved organic matters, TN and TP migrated to the sediment, and then released from the sediment to the water body during dissolution process. However, the amount of those three kinds of dissolved organic matters and TP released from sediment to water in the process of dissolution was less than that transferred in the process of freezing, which means that some pollutants were enriched in sediment in this process. 2) By measuring the concentrations of BPA, E2 and EE2 in the ice-water phase under freeze-thaw alternating conditions, it was found that BPA, E2 and EE2 migrated to the water phase during freezing, but the migration rates were different. 3) The results of correlation analysis showed that SUVA254 was positively correlated with TP during freeze-thaw process. Under the influence of freezing and thawing, the migration trend of aromatic substances and phosphorus-containing dissolved substances is closely related. Conclusions: During the freezing process, pollutants, especially aromatic pollutants, were migrated to and accumulated in sediments. In the process of ice melting, pollutants are released from sediments to water under the influence of temperature and external disturbance. Therefore, during the formation of the surface water ice layer, the concentration of pollutants in the water under the ice increases, while pollutants migrated to the sediment and stay in the sediment. When the ice melts in spring, pollutants staying in sediments will release into water, which lead to the increase of pollutant concentration in surface water in spring and may pose potential risks to aquatic ecosystem health.
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Pepper diseases detection method based on improved Faster R-CNN

YAO Fei, HU ChunQiang

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Pepper disease detection is of great significance for taking effective prevention and control measures in time and reducing the risk of pepper production due to disease. Currently, pepper disease detection technology based on deep learning is still lacking. Based on this, this paper proposed an improved Faster R-CNN pepper disease detection method. The image set of pepper disease was firstly established, then the data of the image set was augmented, and the sample data set of pepper disease was labeled. Then the Faster R-CNN network was pre-trained, and the weight parameters were fine-tuned on the pepper disease data set through the transfer learning mechanism, its mAP reached 89.74%. It can be seen that the detection of pepper diseases by Faster R-CNN has problems of missing detection and low efficiency. In this paper, the network is improved by MobileNetv2 optimization network model combination and regional candidate box optimization, the experimental results of the improved Faster R-CNN network and the classical Faster R-CNN network are compared and analyzed, the results show that: The improved Faster R-CNN detection efficiency is significantly improved, detection speed can reach 10FPS and mAP up to 90.01%, and the missed diseases could also be identified and detected by the network, confirming the feasibility of the improved Faster R-CNN network model for pepper disease detection.
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Topology comparison analysis design and optimization based on dual-excitation units wireless power transfer system

YIN Yong, WANG Chengliang, Xiao Yuhua, WANG Cheng

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Aiming at the optimization problem of the transfer power and efficiency of the rail-type dynamic wireless power transfer (Wireless Power Transfer, WPT) system, a dual-excitation unit wireless power transfer (DEU-WPT) method is proposed, which effectively overcomes the problem of the power electronic devices in the power system need to withstand large current and voltage stress. At the same time, the output characteristics under different topologies and dynamic mutual inductance changes are analyzed. This paper analyzes the working principle and equivalent circuit model of the dual inverter transmitting structure system, discusses the influence of parameter changes on the system, and compares it with the traditional wireless power transmission system structure. The optimal design is obtained through simulation and the experiment is set up. The platform verifies the feasibility of the method.
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Study on pressure relief law of double upper protective layer superposition mining

qinbing, ye donglin, shi zhanshan, sun weiji, li gang, zhang jinjing

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In order to obtain the pressure relief effect of the protected layer under double upper protective layer superposition mining，and the interaction between protective layers. Taking the No. 1 mining area of Pingmei No. 8 coal mine as the engineering background, numerical simulation is used to study the stress distribution law of superposition mining of Ding and Wu coal seams with multiple working faces. The research results show that, when only a single working face of Group Ding is mined to protect the Ji coal seam, stress concentration value of coal pillars at the working face boundary is about 19MPa, the influence range reaches 80m below, the maximum pressure relief value is about 1MPa. When the Group Ding multi-faces protect the Group Ji, the maximum stress value of the sectional coal pillars of Group Ding reaches 39MPa, but the transmission range to the bottom plate is only 26m, the maximum pressure relief value is 2.0MPa. When Group Ding and Group Wu coal seams are overlapped mining with multiple working faces, and the working face and coal pillar are staggered, the stress concentration weakening of the sectional coal pillars, and it is conducive to pressure relief. The stress value of sectional coal pillars is unloaded from 39 MPa to 10 MPa, and the maximum pressure relief value of Group Ji is 6.5 MPa. When a single working face of Group Wu protects the coal seam of Group Ji, the maximum pressure relief value of Group Ji is 4MPa. The double upper protective layer mining can enhance the pressure relief effect and reduce the concentrated stress of the sectional coal pillars. The pressure relief range of the Group Ji has been delineated based on the obtained stress distribution law, and formulated the mining scheme and pre pumping borehole layout scheme of the Ji coal seam working face.
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Vibration analysis of fluid-conveyed single-walled carbon nanotubes embedded in elastic medium under a longitudinal magnetic field

LI Ming, DENG Qian, LV Liu-fei

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Based on nonlocal Euler-Bernoulli beam theory, vibration characteristics are investigated for a fluid-conveyed single-walled carbon nanotube (SWCNT) which is embedded in a elastic medium and subjected to a longitudinal magnetic field. Governing equations of motion are derived for vibration analysis of fluid-conveyed SWCNTs, where the Lorentz magnetic force and the surrounding elastic medium have been taken into consideration. Subsequently, differential transfermation method (DTM) is employed to compute the critical fluid velocity for fluid-conveyed SWCNTs with simple surported boundary condition. The obtained results are followed by a detailed parametric study of the effects of nonlocal parameter, elastic foundation parameter and longitudinal magnetic field on the vibration of fluid-conveyed SWCNTs. Through various numerical studies, the coupling effects of nonlocal parameter, elastic foundation parameter and the strength of magnetic field on the critiacal fluid velocity of the fluid-conveyed SWCNT are carefully examined.
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Research on power fluctuation suppression technology of dynamic wireless charging system

Yin Yong, Xu Benchao, Wang Chengliang, Xiao Yuhua

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In order to reduce the power drop of dynamic wireless charging system at the transmission rail switch, a new coupling mechanism of dual channel dynamic wireless charging system is designed. The LCC-LCC compensation topology is selected to design two energy transmission channels. By using the constant current characteristics of LCC-LCC compensation topology, the relationship between system output and loss and two channel coupling parameters is deduced, which realizes relatively stable power transmission and improves the anti offset characteristics and anti drop ability of the system. Finally, the proposed method is simulated and tested to verify the feasibility of the two-channel dynamic wireless power transmission scheme.
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Elementary solution of the elastic half-plane containing a rectangular inclusion: theory and applications

Xie Dongdong, Jin Xiaoqing, Jiang Zhizhen, Qian Houpeng, Li Pu

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Inclusions in engineering materials will create a disturbance to the elastic fields. When an inclusion is located in the vicinity of the surface, the interactions between the inclusion and the surface are often difficult to be solved analytically. The elementary solutions of the displacements and stresses caused by a rectangular inclusion contained in an elastic half-plane are derived in closed-form. Accordingly, the resultant elastic fields produced by any arbitrarily shaped inclusion may be solved through a "discretization-superposition" scheme. In contrast, the traditional Finite Element Method needs to mesh the semi-infinite matrix region which is much larger than the size of the inclusion, while the mesh needs to be sufficiently refined at the inclusion/matrix interface to attain a satisfactory accuracy. By taking advantages of the elementary solutions of rectangular inclusion, the proposed semi-analytical method merely performs the numerical discretization within the inclusion region, leading to remarkable savings on the meshing efforts and memory storage. Benchmark examples are reported for an elastic half-plane containing either regular hexagonal or circular inclusion, and the results are validated with those obtained by the commercial Finite Element software to show the correctness and effectiveness of this proposed semi-analytical method.
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Semantic Attention Graph Representation algorithm for Multi-Label Image Classification

YANG Guang-chao, CHEN Ke

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In the traditional multi label research, they can only roughly locate the semantic regions of the image, and can not fully excavate the label correlation between the semantic regions. To solve the above problems, the author proposes a Semantic Attention Graph Representation (SAGR) algorithm that composed of two key modules for multi-label classification : 1) Semantic Location(SL) module that integrated the semantic information of all labels categories in the image for learning to obtain the feature representation of each label category; 2) Semantic Correlation(SC) module that used graph structure to interact with the obtained semantic feature representation, and captured the dynamic label dependency in image by graph attention network. The experimental results of Pascal VOC2007 and MirFlickr25k datasets show that SAGR algorithm is better than traditional methods, and the mAP of SAGR can be improved to 93.5% and 84.2%.
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Three-dimensional pore structure of granular sludge in biological wastewater treatment system: Taking Anammox granules as an example.

lengjixuan, fuhuimin, yanpeng, chenyoupeng

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The three-dimensional(3D) structure distribution of granular sludge is essential to its settlement ability and stability. However, there is a lack of research on the 3D pore structure and distribution characteristics. In this study, the anerobic ammonium oxidation granular sludge was scanned through synchrotron radiation X-ray phase microscopic computed tomography，with its structure being reconstructed by Avizo. The diameter, spatial distribution, and fractal dimension of the pore structure were obtained to establish the pore network model of granular sludge. Subsequently the calculation of absolute permeability was made. It is hoped that this research will make a contribution to the theoretical basis for the stable and efficient application of granular sludge system in sewage treatment.
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Shared knowledge guidance and modal consistency learning for Visible-Infrared person re-identification

xu kai xiong, li fan, li hua feng

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In the visible-infrared cross-modality person re-identification(VI-ReID), how to extract discriminant features which are not affected by modal discrepancy is critical to improve recognition performance. The current common solution is to learn the shared feature representation of two modalities by using a dual-stream network, however, these methods did not mine more shared knowledge between the modalities, and the discrepancy between the modalities still exits. Therefore, Shared Knowledge guidance Modal Consistency Learning(SKMCL) is proposed. This method is composed of cross-modal shared knowledge guidance(SKG) and modal consistency learning. The former fully explore the shared knowledge between modalities by cross-modal attention mechanism and serves as a guide to assist the model to extract discriminative features, the latter reduce the discrepancy of two modalities through the adversarial learning of the designed modal classifier and the dual-stream network, and the two modules cooperate with each other to strengthen feature learning. Meanwhile, in order to further reduce the modal discrepancy of two modalities, a features mixing strategy is introduced to enhance the ability of the dual-stream network to extract modal consistency features. The performance of the proposed method on the two public datasets SYSU-MM01 and RegDB obviously superior to that of related works. The accuracy of Ramk1/mAP is 58.38%/56.10% and 87.41%/80.75%, respectively, which proves the proposed method is effective. The source code has been released in https://github.com/lhf12278/SKMCL.
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Research on method of power data sharing channel transfer for MC-WPT system based on ASK and FSK mixed modulation

yin yong, Fan Yuanshuang, Xu Qingqiang, Xiao Yuhua, Wang Chengliang, Yang qingsheng

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In view of the low transmission rate of MC-WPT energy signal simultaneous transmission system, this paper proposes a transmission method of energy signal shared transmission channel based on FSK and ASK hybrid modulation. In this method, two different frequency carriers are transmitted between the primary side and the secondary side of the system by using the double resonance network and the impedance network. The traditional ASK modulated single frequency carrier is changed into the dual frequency carrier. At the same time of ASK modulation, the FSK modulation is mixed to improve the system signal transmission rate. The dual resonant topology and the simultaneous interpreting topology of energy transmission using dual resonant topology are presented. The mathematical models of energy transmission and signal transmission are established respectively. Finally, the feasibility of the method is verified by simulation.
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Energy absorption characteristics and impact resistance evaluation of honeycomb structures under different unit cell morphologies and bearing directions

ZhangYongXiang, Wang Rui Zhi

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In order to study the influence of unit cell shape and loading direction on the mechanical properties and buckling mode of honeycomb structures, different honeycomb structures were prepared by additive manufacturing technology, and static load tests and dynamic simulations were carried out. The results show that the stress curve of the honeycomb structure shows a four-stage change trend; the hexagonal honeycomb structure supported by the unit cell diagonally has the highest platform stress and total strain energy density; the collapse of the unit cell is mainly due to the shear deformation of the unit cell, and the quadrilateral The honeycomb unit cell undergoes severe buckling instability during shear deformation; the instability mode of the overall honeycomb structure can be divided into two types: oblique and transverse initial shear bands; in the simulation of large-scale honeycomb structures, its anti-shock ability It has been evaluated that the energy absorption value of the structure can reach 105J, which meets the requirements of the energy absorption shock absorber. The obtained conclusions can provide a theoretical basis for the design of the hydraulic support anti-shock energy absorber.
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Laser Ultrasonic Visual Imaging Detection of Corrosion Damage

SHANG Xiaozhuang, LIU Yaolu, ZHOU Shijie, NING Huiming, HU Ning

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Corrosion damage exists extensively in industries of national defense technology and transportation, which threatens seriously the safety and reliability of the structure. Therefore, it is of great significance to monitor corrosion damage for safety. In this paper, according to the theory of laser ultrasound, an automatic laser scanner detection experimental system is designed and developed. The laser scanning experiment was carried out on the corrosion damage in the aluminum plate through this system, and the relationship between the Lamb wave energy, amplitude and corrosion was analyzed, and visualize the damage area with the maximum amplitude according to the principle of "elastic wave energy flow method". Finally, we propose the amplitude integral ratio method, which can be used to evaluate the degree of corrosion damage, and the evaluation and analysis of aluminum plates with different corrosion degrees are completed. This research can realize the rapid detection and evaluation of corrosion defects, and the detection results are intuitive, showing a huge application prospect.
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Measurement method of occupancy based on active infrared intrusion detection

Xu Wenlu, LIU Meng, LIU Huan

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Occupancy is closely related to the building energy consumption system. Monitoring occupancy is one of the hot issues in the direction of building energy consumption behavior. Infrared sensing is a widely used method in existing research methods. Its measurement precision is related to installation height, personnel passing speed, personnel somatotype and other factors. The active infrared intrusion detector was selected to study the influence of installation height, passing speed and personnel somatotype on the measurement precision of occupancy according to the indoor occupants" activities. The research results show that the measurement precision first increases and then decreases with the decrease of the installation height when considering various personnel somatotype and passing speed. The slower the passing speed, the higher the measurement precision. When v ≥ 1.4m/s, the precision is less than 60 %; when 1.0 m/s ≤ v < 1.4 m/s, the precision is 70 % ~ 81 %; when v < 1m/s, the precision is higher than 95 %; When v < 0.8m/s, the precision is 100 %. The height and Body Mass Index of the tested people are positively correlated with the measurement precision. Through the analysis of different operating conditions, an estimation method of comprehensive precision applied to actual scenes is proposed.
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Current situation of landfill leachate production and treatment prospect in China

ZHANG Yanyan, ZHENG Zhihong, LIU Hongliang, FU Manqin, LI Lei, PENG Xuya

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The disposal of leachate is highly valued by government due to its characteristic of high concentration of pollutants and ecological risk. Based on literature survey, this paper investigated the output and pollution characteristics of different kinds of leachate from transfer stations, incineration plants and landfills. The development targeting on leachate disposal technology and management was prospected based on the current solid waste treatment policy. The results show that with the construction of "Zero waste cities", the difficulties in leachate disposal can be alleviated both in terms of quantity and quality with the implementation of policies such as garbage classification and "zero landfill" of crude waste, while middle and aged-landfill leachate has become the main target in the future. The technical mode of "pretreatment + biological treatment + advanced treatment" was applied as an effective means for leachate disposal. With the wide implementation of garbage classification, particular attention was given to local optimization in pre-treatment stage. The development of low carbon and carbon-free denitrification process can significantly achieve increased operational efficiency and consumption reduction during biological treatment stage. In the stage of advanced treatment, non-membrane full quantification treatment process was the main focus for proper disposal of concentrated leachate and trace organic compounds removal, which is helpful to achieve a more comprehensive risk control on leachate pollution.
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Research on preparation and properties of high strength and high modulus PVA/CNF/GO composite fiber

LEI ling, NING Hui-ming, Alamusi

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The high-strength and high-modulus PVA/CNF/GO composite fiber was prepared by wet spinning and hot drawing process. The reinforcement effect of Cellulose nanofibrils (CNF) and graphene oxide (GO) on polyvinyl alcohol (PVA) fiber was studied. The effects of CNF content and hot drawing temperature on the tensile properties of fibers were discussed. When the content of CNF is 6% and the content of GO is 1%, the PVA/CNF/GO composite fiber prepared by wet spinning has excellent tensile properties after three times of hot stretching treatment at 160 ℃. Its ultimate tensile strength and elastic modulus are 1.09±0.11 GPa and 21.87±3.03 GPa respectively, which are 45% and 63% higher than those of pure PVA fiber, and 523% and 271% higher than those of PVA/CNF/GO composite fiber without hot stretching treatment. Meanwhile, the composite fiber has good biocompatibility and potential biological application value, which can be used as surgical sutures to provide appropriate tension for tissue regeneration.
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Construction and mining of knowledge graphfor power grid intelligent dispatching

PENG Fei, WANG Duoqing, WU Yi, DENG Wenchen, AN Fengqiang, CHEN Zhikui

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With the development of smart power grid, aSquantitySof monitoring devices are deployed to form sensor networks, resulting in a large amount of heterogeneous data. Traditional data management methods are difficult to effectively utilize the massive data. Because of the strong knowledge representation and reasoning ability, power knowledge graph can comprehensively and systematically display the business information, technical knowledge, industry standards and the internal relationship of these information. In this paper, a knowledge graph model of power grid scheduling rules is constructed by graph convolutional network (GCN), and the features of the knowledge graph are extracted based on graph neural network (GNN).SSpecifically, we obtain the entity words and relation words in the specifications from the smart grid dispatching control system with the knowledge extraction method, so as to clarify the object entity set and eliminate data ambiguity. Then, get the relationship between entities to construct domain knowledge graph, and normalize the object relation network of power intelligent dispatching. Finally, we learn the characteristics of the grid dispatching knowledge graph and mine the hidden relations between entities with the graph neural network, which can provide a comprehensive decision basis for the development of the grid dispatching system technology. The technical specification of smart grid dispatching control system involved in this paper is provided by The Northeast Branch of State Grid, and the method proposed in this paper is verified on the real data set.
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Research on the Output Stability of the EV-DWPT System Based on the Permeable Rails

wang chengliang, wang honghua

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Based on the power drop caused by the mutual inductance fluctuation between the primary and the secondary coils in the dynamic process of the short-rail structure in the EV-DWPT system, this paper proposes an optimization design technology utilizing the pulse synchronization control method for the permeable rails structure. Firstly, the expressions of the output power and the primary and secondary coil current were deduced by analyzing the dual transmitter and single receiver circuit based on the LCC-S resonant topology. Secondly, the effects that the length of the permeable areas and the number of the coils on mutual inductance were analyzed by COMSOL and pulse synchronization control method. Finally, the simulation model of the circuit was established through the simulation platform PLECS. The simulation results show, by utilizing the pulse synchronization control method, the fluctuation of the mutual inductance is about 3% in the dynamic process of the coupler. Comparing to the 56% of the single exciting mode and the 32% of the traditional rectangular coil, the fluctuation of the mutual inductance has been greatly inhibited. And the output power fluctuation of the EV-DWPT system designed in this paper is ±3.2%. Keywords：wireless power transfer, EV-DWPT, impulsive synchronization, permeable rail, power fluctuation
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An Edge-Cloud Collaborative Computing Framework Oriented to Edge Model Scenario Adaptive Tasks and Its Application in Object Detection

HAN Tongxin, REN Hao

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As modern IoT systems tend to become increasing larger, complex and intelligent, which makes requirements become higher on the perception and computation capabilities of calculation devices at the edge. The future development of cloud computation focuses on enabling the collaboration of low-power, high-real-time edge computation with low-cost and high-performance. In order to realize the collaboration between edge and cloud to maximize the application value of the advantages of edge and cloud computation, this paper proposed a computing framework for edge model scenario adaptive tasks in edge-cloud system. Firstly, the edge-cloud collaboration mechanism model is constructed based on the difference between inference results of cloud-side model and edge-side model. Secondly, a small amount of edge application-side task samples are employed to incrementally re-train the cloud-side model to the adaption performance of edge-side transferred model from the cloud-side model. Finally, the performance of the edge-size can be maintained by the real-time monitoring of the side-side reasoning results.
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Research on Cold Load Prediction Method of Shopping Mall Building Oriented to Functional Zoning

ZHAO Anjun, Yang Hangjie, Jing Jing, Zhang Mengzhi, Jiao Yang

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Aiming at the problem that cooling load prediction of overall buildings for large-scale shopping malls cannot provide a reasonable control strategy on demand for various areas of the shopping mall. According to the characteristics of the cooling load in different areas in the mall, the grey correlation analysis method was used to screen the key influencing factors of cooling load in different areas of shopping malls, and a district cooling load forecasting model based on attention long-short term memory (Attention-LSTM) neural network was proposed. LSTM network fully considers the nonlinear relationship between air conditioning cooling load and related characteristic variables. Characteristic attention autonomously analyzes the relationship between historical information and input variables to extract important features. Time-series attention selects historical information at key moments in the LSTM network to improve the stability of the forecast effect
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Analysis of tropospheric classical model of deep space interferometry

Chai Tianyi, Lu Weitao, Ma Hong, Jiao Yiwen, Sun Kuanfei, Jing Mengjiao

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Tropospheric delay is one of the important error sources of deep space interferometry.In this paper, the influence of temperature, humidity, pressure and other meteorological parameters on Saastamoinen zenith delay model is firstly analyzed, and the influence amplitude of each parameter is obtained, and the requirements of certain tropospheric delay accuracy on the accuracy of meteorological parameters are given.Then, the mapping amplitude deviation of NMF and VMF at different elevation angles is compared and analyzed. The results show that when the elevation Angle is higher than 10°, the mapping amplitude deviation is less than 0.005.However, NMF is more suitable for deep space interferometry because of its simple form and low computational cost.The influence of meteorological parameters on measurement accuracy and the analysis of mapping model provide basis for the design of meteorological parameters measurement accuracy index and the selection of mapping function applicability.
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Study on the characteristics of a manganese oxidizing bacterium AL-6 coupled with grapefruit peel biochar to repair groundwater polluted by electrolytic manganese slag field

AN Qiang, JIAO Yixiao, ZHANG Chenyi, DENG Shuman, JIN Ningjie, YANG Maolin

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In order to study the remediation of complex wastewater from the groundwater polluted by the electrolytic manganese slag field, biochar was made from agricultural waste grapefruit peel as the raw material for the strain Acinetobacter baumannii AL-6 immobilized carrier (MBC), and the strain biochar coupling system (MBC) was obtained. The comprehensive treatment capacity of the coupling system for composite wastewater containing manganese, ammonia nitrogen and high calcium and magnesium ions was explored, and a Sequential Batch Reactor (SBR) was constructed to explore its application potential in wastewater treatment. The experimental results showed that MBC removed 98.46% of manganese within 48 h. Compared with two independent experimental groups (biochar group, strain AL-6 group), MBC has an excellent synergistic effect on the removal of manganese, and the average removal rate of manganese is 15.87 mg L-1 h-1, which is 1.09 times of that of the strain AL-6 and 14.33 times of that of the biochar group. In addition, MBC has a maximum removal ratio of 71.92% for ammonia nitrogen, and also has a certain removal effect for calcium and magnesium ions, with removal ratios of 41.46% and 26.95%, respectively. In the SBR, 90.1% of manganese and 85.44% of ammonia nitrogen are removed. The results show that immobilized strain AL-6 on grapefruit peel biochar has great application potential and can be used to treat wastewater polluted by electrolytic manganese slag.
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Speaker diarization based on attention residual network

FANG Yi-fan, TIAN Peng, YUAN Fan-ning, RONG Yu-jun

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The speaker feature extraction network does not consider the differences of speech frame and gives each frame the same weight, which leads to the problem that the speaker diarization result is not ideal. Aiming at this problem and combing with the outstanding performance of residual network structure in visual tasks and scalable design, a method that combines residual connection, asymmetric convolution, and attention mechanism is proposed. The speaker diarization network architecture based on the ResA2Net module was constructed to extract speaker features. Residual connection structure was used to reduce the computational complexity and enhance the model learning ability. Attention module was introduced to capture and emphasize the critical information of speaker's characteristics and improve the distinguishability of speaker's characteristics. The nearest neighbor propagation algorithm was implemented to cluster the speakers. Finally, the trained model was used for speaker diarization test. Compared with various speaker diarization models, the diarization error rate (DER) of the ResA2Net model reaches 7.34%, which is lower than other models, indicating that our model can perform effectively in speaker diarization work.
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Study on safety of four circuit transmission line tower under stochastic wind field

Getu Niu, Yan Chen, Xiaolin Li, QIan Zhang, Qingshan Wang, Xin Zhang, Ziqi Fu, Bo Yan

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With a typical section of 220kV four circuit transmission line in West Inner Mongolia, the structural strength and fatigue life of the towers under stochastic wind are numerically studied by means of the finite element (FE) method. The FE model of the tower-line system is established using the ABAQUS software. Considering the topographic characteristics of the West Inner Mongolia, stochastic wind fields are simulated numerically to calculate the dynamic response of tower-line system. According to dynamic responses of the tower-line system under wind load, the dangerous zone of the tower is determined and its 3D solid FE model is set up. A hybrid FE model combined the local 3D model with the spatial beam model of the other portion of the tower is constructed. The time histories of the reaction forces at hanging points of the conductors and ground wires are applied on the hybrid FE model of the tower to simulate its dynamic responses under wind load. The structural strength and fatigue life of the tower under two stochastic wind fields and with different bolt preloads are numerically investigated. The results show that the bolt looseness affect the strength and fatigue life of the tower obviously and may be one of the main reasons of tower failure.
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Simulation and experimental study of MOEA/D improved washout algorithm based on motion test platform

Liu Weichao, Wang Hui

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The parameter adjustment of the wash algorithm greatly affects its performance. Aiming at the deficiency of parameter adjustment of the current classical wash algorithm when it is applied to flight simulator, an improved wash algorithm based on MOEA/D multi-objective optimization is proposed. In order to minimize the human perception error between real and simulated motion, and to develop the platform under the condition of motion space limitation, several evaluation indexes of the washing algorithm were considered in the optimization process, and the parameters of the washing algorithm were optimized synchronously. To verify its effectiveness,the motion test platform of flight simulator was established and the improved algorithm was applied to optimize calculation. The washing algorithm before and after optimization is simulated and tested, results show that the optimized algorithm has great improvement in the homing response, phase delay and perceived amplitude, and has better stability. At the same time, optimizing the platform workspace and increasing the dynamic fidelity.
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Stress calculation of electrode nanoparticles and adhesives for Lithium-ion batteries during charge discharge cycles

ZHANG Fuliang, YANG Rukun, ZHANG Qiang, HE Hong, YU Hongjie

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As an important material for lithium battery electrode manufacturing, adhesive is the main undertaker of the mechanical properties of electrode plate although its dosage is small. Most of the existing rheological models of composite electrode were assumed the binder layer as linear elastic material, which was difficult to describe the complex mechanical behavior of it. Therefore, in order to deeply understand the mechanical behavior of the electrode plate Nano particles and adhesive during the charge and discharge process, the Neo Hookean hyperelastic model was fitted based on the existing experimental data in literature. The results show that the main plastic deformation occurred during the first charge discharge cycle, and the maximum stress evolution of the bonding layer is similar to that of the nano particles. With the increase of the thickness of adhesive layer, the maximum stress at the interface of adhesive layer would decrease gradually.
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Open-plate Capacitor based In-situ Monitoring for Magnetorheological Fluid Settling

Hang SU, Honghui ZHANG, Zhiyuan ZOU, Changrong LIAO

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It is of great significance to establish an in-situ settlement monitoring system for the magnetorheological (MR) fluid in devices. By studying the relationship between the concentration gradient of MR fluid and the dielectric constant of the sediment, the monitoring method and system based on an open-plate capacitor is designed. The influence of center pillar height on the electric field distribution is simulated, and the in-situ monitoring of MR fluid show that the system can effectively measure the static settlement of magnetorheological fluid, the dielectric constant of the sediment increases with the heightened concentration, and the sedimentation ratio lowers with the development of the settling process.
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Study on the phase and microstructure of lignite char at different pyrolysis temperatures

zhangchunhua, wangyiming

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Pyrolysis is an important means of lignite modification and upgrading. In order to study the changes of phase and microstructure of lignite char prepared at different pyrolysis temperatures, lignite samples from Puhe coal mine in Shenbei mining area, were pyrolyzed at three pyrolysis characteristic temperatures (400 ℃,700 ℃ ,1000 ℃) to prepare lignite char samples. The physicochemical structure of lignite coke samples was analyzed by SEM, XRD, Raman, FT-IR, XPS, N2 adsorption experiments. The results show that with the increase of pyrolysis temperature, the aromaticity of coke sample is enhanced, the oxygen-containing functional groups O-H, C=O and C-O of coke sample are greatly reduced, surface carbonaceous functional groups, the intensity of C-C increased and the intensity of C-H reduced. At 400 ℃ and 700 ℃, the microcrystalline structure defects of coke samples increased, while at 1000 ℃, the microcrystalline structure of coke sample tends to order and changes to graphitization. The specific surface area and pore volume of coke samples first increased and then decreased with the increase of pyrolysis temperature. 700 ℃ coke sample has the largest specific surface area (117.0637 m2/g) and pore volume (0.068134 cm3/g). Increasing pyrolysis temperature is conducive to the development of microporous structure of coke sample.
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Burst Detection in District Metering Areas Based on Long Sequence Time-series Forecasting

WEN Si-qi, LONG Tian-yu

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Pipe bursts occur in water supply networks, and the identification quick detection of bursts is a long-standing problem for water supply companies. For the rapid detection of burst pipes in metering sub-district water supply networks of district metering area, a new prediction-classification-correction three-stage Infomer-Zscore algorithm is proposed. The Infomer-Zscore algorithm solves the problem of low data processing efficiency and abnormally low water consumption in traditional methods. In the prediction stage, using the deep learning Informer algorithm to predict long sequence time-series Long Sequence Time-series of pressure data for the pipe network, improving the accuracy of water pressure prediction and the efficiency of data processing. In the classification stage, improved robustness of water pressure data over time by using a multi-threshold classification method .The Infomer-Zscore algorithm achieved a 90.9% true positive rate (TPR) ,a 1.7% false positive rate (FPR) and a 99.5% detection accuracy (DA) in the pipe burst simulation test. Long sequence Sequence timeTime-series pressure forecasting can be used not only for burst identificationdetection, but also for effective pressure control in the network to reduce the risk of bursts.
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Re-recognition of design and safety evaluation of high-grade steel mountain pipeline

HU Wen-jun, ZHAO Yu, HU Kai-heng, CHEN Gui-yu, FU Kai-wei, ZHANG Xiao-peng

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s: Permanent ground deformation (PGD) is one of the main causes of buckling, fracture and leakage of mountain pipeline and heavy loss of life and property.Design and safety evaluation of mountain pipelines in PGD zone with the existing “Strain-based method” and technical standards urgently awaiting further research figures out the dangerous statuses of in-service high-grade steel pipelines. The current situation of “strain-based” failure discrimination is firstly analyzed and summarized. Technical actualities and imperfections of strain calculation methods (analytical, numerical, and experimental methods) and safety evaluation methods for pipe-soil interaction are indicated by the main patterns of pipe failure with the "allowable strain" and "calculated strain" under complex PDG working conditions. Future research content and path of the design and safety evaluation based on actual work conditions and pipe-soil interactions are synthetically proposed, while considering the future development trend and production needs of mountain pipelines in China.
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Analysis of Lubrication Characteristics of Plunger Pair of Pressure Compensation Pump in Deep Water

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The pressure-compensated plunger pump can better adapt to the extreme deep water environment, but the extreme deep water environment will change the lubrication characteristics of the plunger pair, affecting its underwater working performance and application range. Taking the lubrication characteristics of the auxiliary oil film of the plunger of the pressure compensation pump as the research object, considers the influence of environmental factors such as deep water temperature and pressure on the viscosity, density and other media properties, establishes a numerical model of the auxiliary oil film of the plunger in the deep water environment, and proposes the In the eccentric direction, the method of coordinate rotation optimization and finite difference discretization is used to solve the parameters that characterize the lubrication characteristics such as the thickness of the plunger pair. The results show that when the water depth is 1000m and the rotation angle of the main shaft is about 90o, the secondary oil film of the plunger appears in an extremely thin area less than 1μm, and the pressure difference reaches 80MPa. When changing the spindle speed and the inclination angle of the swash plate, the leakage and axial friction changes more significantly under air conditions. Under different water depths, there is a positive correlation between the axial friction and the water depth, but the change in leakage is the opposite. Related research can provide a useful reference for the design and development of pump plunger pairs in deep water environments.
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Research on Text Location and Recognition Method of Railway Computer Interlocking Interface Based on Deep Learning

HE Tao, JI Yi

Abstract: (755) HTML (0) PDF (0.00 ByteKB) (0)

In order to effectively solve the problems of low efficiency and low accuracy of manual testing of railway computer interlocking systems, a deep learning model for text localization and recognition of the upper computer interface of railway interlocking is proposed. First, by comparing the strategy of combining the text localization model based on CTPN (Connectionist Text Proposal Network) neural network with the four convolutional neural networks of ResNet50, AlexNet, ZF and VGG16, the optimal feature extraction network VGG16 was selected, which enhanced Convolutional feature maps represent the detailed features of high-level semantic information to facilitate the location of small text areas. Secondly, comparing the performance of common target detection models on the text localization effect and adopting the dropout method, the generalization ability and robustness of the CTPN network of the text localization model are improved. Then, the use of a combination of horizontal projection and vertical projection can effectively avoid problems such as text sticking on the interface of the interlocking upper computer. Finally, the improved AlexNet network is used to output the text recognition results. By verifying the text positioning and recognition data set of the interlocking host computer interface in the TensorFlow environment, the results show that the accuracy of the text positioning of the CTPN network in the railway interlocking host computer interface has reached 87.98%, the recall rate is 73.33%, and the average index of harmony is 80.39%; The improved AlexNet network achieves 89% accuracy in text recognition. It shows that the method in this paper can accurately locate and recognize the interface text of the railway computer interlocking upper computer, and provide reliable data support for automatic routing and automatic analysis of test results during the automatic interlocking test process.
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The influence of the different part of the claw alternator to the aerodynamic noise

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In order to understand the influence of different parts on the aerodynamic noise of the claw alternator for vehicle at high speeds, this research studies the aerodynamic noise characteristics of the claw alternator. The no-load acoustic power level experiment of the claw alternator for vehicle is carried out to verify the accuracy of the numerical simulation. The noise sources of each order are determined by using with or without front and rear fan blades, claw and cylinder envelope instead of claw pole. The contribution of front and rear fan blades and claw to different orders of noise are Clarified. The results show that dipole is the main noise source at high speed. The front blade mainly affects the aerodynamic noise in 8th, 10th, 12th and 16th order. When the front fan is removed, the aerodynamic noise in 12th and 16th order is reduced by 6.54dBA and 9.04dBA, respectively. The rear fan mainly affects the aerodynamic noise in 6th, 8th and 10th order. When the rear fan is removed, the aerodynamic noise in 6th, 8th and 10th order is reduced by 11.75dBA, 2.42dBA and 7.38dBA, respectively. The influence on the aerodynamic noise is small with or without claw, but the flow field is affected when the cylinder envelope is used to replace the claw pole, and the 8th order noise has a certain change. It also shows that the front and rear fans are main sources of the aerodynamic noise.
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Voiceprint recognition based on knowledge distillation and ResNet

RONG Yujun, FANG Yifan, TIAN Peng, CHENG Jiawei

Abstract: (1013) HTML (0) PDF (0.00 ByteKB) (0)

Channel mismatch and incomplete acquisition of voiceprint features under short speech or noise conditions are two thorny problems for voiceprint recognition. This paper proposes a solution that combines traditional techniques with deep learning: A I-Vector model was used as the teacher model to conduct knowledge distillation of the student model ResNet, a ResNet network based on metric learning was constructed, including an attentive statistics pooling layer to capture and emphasize the critical information of voiceprint features and improve the distinguishability of voiceprint features, and the mean square error (MSE) was combined with the loss based on metric learning to reduce computational complexity and enhance model learning capabilities. The trained model was then used for the voiceprint recognition test. Compared with the voiceprint recognition model under various deep learning methods, the equal error rate (EER) was the lowest, and the equal error rate reached 3.229%, indicating that the model can perform voiceprint recognition more effectively.
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Research on Visual Servo Control Method Based on Image Trajectory Planning and Timing Control

Jiao Wentan

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A visual servo method based on image trajectory planning and sequential control was proposed for uncalibrated eye-in-hand robot system. First the trajectory planning method in image space and task space was presented. Second the Kalman filter was adopted to estimate the relative pose of the target to camera, and combined with camera measurement, the adaption of Jacobian matrix was realized. A visual servo controller with image feedback was designed to realize the visual tracking of target. At the end of this paper, the algorithm was verified by MATLAB simulations and experimental researches, and compared with classical PBVS and IBVS method. The results verify the effectiveness of the algorithm.
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Research Progress of Odor Reproduction inMachine Olfaction

LIU Qi, LUO Dehan, WEN Tengtrng, YI Haitao

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Today"s society has entered the stage of rapid development of artificial intelligence, and machine olfaction is an emerging technology developed in the 21st century. Odor reproduction is an important part of machine olfactory system, which has attracted increasing attention from the scientific and industrial circles. This paper focuses on the theory of odor reproduction and the way of odor generation. At the same time, it classifies, compares and analyzes the existing odor reproduction technology. The current challenges of odor reproduction are summarized and its development prospects are presented.
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Research on LTE-R Handover Algorithm Based on Improved Grey-Markov Model

WANG Rui-feng, FAN Wen-jing

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During the handover process of high-speed trains, due to the influence of path loss and terrain, the Reference Signal Receiving Power (RSRP) fluctuates up and down, and the handover decision method based on the traditional A3 event will cause ping-pong. The occurrence of handover and the drop in handover success rate. To solve this problem, a handover algorithm based on an improved gray-Markov model is proposed. The received power of the reference signal is processed and predicted by an improved grey-markov model, and the handover process is executed by using the processing result as the handover decision based on the preloading method. The simulation results show that by using the improved handover algorithm, the fluctuation of RSRP values received by the train can be significantly improved, the ping-pong handover probability is lower, and the handover success rate can be effectively improved.
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An Improved Lightweight Network for Image Dehazing

Tang Jian, Che Wengang, Chen Wenbing, Yang Shengrong

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In order to solve the problems of high model complexity and large parameters in image dehazing using convolutional neural network, a light image dehazing network (LDNet) is proposed. Firstly, the expression formula of atmospheric scattering model is improved to eliminate fog noise directly and reduce the cumulative error of intermediate variable estimation. Secondly, a reverse residual network module with attention mechanism (RNAM) is designed, which can extract image features at multiple scales, pay attention to the important semantic information in the image, and solve the problems of large network parameters and high complexity. Finally, L1 smoothing loss function and MS-SSIM loss function are used as joint loss functions to minimize the distance between the restored image and the real image. The experimental results show that the proposed algorithm is superior to other contrast algorithms in terms of SSIM and PSNR on the composite data set of reside, and can achieve good dehazing effect in both synthetic images and real scenes, and the method has the characteristics of less parameters and fast operation.
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Text representation method combines label information and graph convolutional network

WANG Hongbin, LUO Gaorong, ZHANG Yafei, LI Runxin

Abstract: (767) HTML (0) PDF (0.00 ByteKB) (0)

Text classification is a basic research in natural language processing, which aims to output specific label categories for input text. And text representation is the intermediate link of text classification and an important content of text classification. Aiming at the problem that short text has less semantic information and is difficult to represent, this paper proposes a text representation method combines label information and self-attention graph convolutional neural network. This method uses the semantic relation between tags and texts to construct a specific single text representation based on tags, and then extracts the global features of multiple texts by using the self-attention graph convolution neural network to obtain a specific text representation fusing the global features. Finally, the text is input into the classifier to obtain the classification result. The experimental results based on R8 and MR show that compared with the other models, our model increases the F1 values and accuracy by 2.58% and by 2.02% on the MR data; and increases the F1 values and accuracy by 3.52% and by 2.52% on R8 dataset.
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Learning implicit surfaces from point clouds by multi-view projection

jin shi

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Point cloud reconstruction must deal with the noise, the holes and uneven sampling problems in acquisition. Traditional methods lack the way to learn prior knowledge from large datasets of high-quality geometric models. This paper proposes an end-to-end reconstruction method by combining multi-view projection and implicit function. First the depth map is obtained by projecting the point cloud to multiple views. The convolution-based encoder transforms the depth map into feature space, at the same time denoising and complementing the feature. Implicit function is implemented with Multi-layer Perceptron (MLP), and is used to represent geometry. In the training process, the high-quality mesh is sampled, the encoder and implicit function are supervised by the pairing pointclouds and implicit values of sampling. Experiments are carried on several datasets to show the effectiveness of the new method. By comparing with traditional method and existing data-driven methods, it shows the new method significantly improve the reconstruction details while suppressing scanning noise, and complement the holes in more natural way. The pre-trained model is directly applicable to multi-view depth capturing system, and can automatically balance the degree of denoise and preservation of detail, and reconstruct a visually acceptable geometric surface on real data.
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Knowledge guidance and fine-grained information enhancement for Unsupervised domain adaptation person re-identification

DONG Neng, XIE Minghong, ZHANG Yafei, LI Fan, LI Huafeng, TAN Tingting

Abstract: (549) HTML (0) PDF (0.00 ByteKB) (0)

Unsupervised domain adaptation aims to transfer the source domain knowledge to the target domain dataset, which is a very important task in person re-identification. In reality, the collected data often has video frame information. Therefore, it is very easy to obtain pedestrian labels from a single camera view in the target domain dataset. However, the existing methods ignore the available information, which limits the improvement of recognition performance. For this reason, knowledge guidance and fine-grained information enhancement for unsupervised domain adaptation person re-identification is proposed. In this method, a new paradigm with a single-view pedestrian sample known in the target domain is developed to fully mine the useful information in the target domain. At the same time, the source domain knowledge is used as a guide to assist the model to extract the discriminative features of pedestrian images in the target domain. Compared with the existing knowledge transfer strategies, this knowledge-guided approach can effectively alleviate the domain shift. Furthermore, the local information of pedestrians is embedded into the global feature, and the fine-grained information of the feature is enhanced. Experiments on two publicly datasets fully prove the effectiveness and superiority of the proposed method. Code: https://github.com/lhf12278/KG-FGIN
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A fast life prediction method for hard metals under multiaxial high cycle fatigue loading

LIU Tianqi, ZHANG Guangxin, ZHANG Tian, LIU Hao, QI Xinxin, SHI Xinhong

Abstract: (506) HTML (0) PDF (0.00 ByteKB) (0)

Based on the study of multiaxial fatigue life of 30CrMnSiA steel, the concept of equivalent S-N curve is proposed in this paper. Based on the equivalent S-N curves, an empirical formula for predicting multiaxial fatigue life of hard metal materials is established. The empirical formula is simple and convenient for engineering application. In addition, the empirical formula is used to predict the multiaxial fatigue life of various hard metal materials in the literature. Results show that more than 94% of the data points are in the ±3 times fatigue life scatter band, and more than 81% of the data points are in the ±2 times fatigue life scatter band.
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A Study on the Traceability Algorithm of Automatic Fish Based on Deep Learning

huangya, gaomin, tianqingbin, wangkai

Abstract: (633) HTML (0) PDF (0.00 ByteKB) (0)

In recent years, with the public paying more and more attention to food safety, the traceability technology has promoted the rapid development in the food industry.In order to study the automatic traceability algorithm of bighead fish, this paper chose the image of bighead fish as the research object to explore the algorithm of automatic traceability of bighead fish, analyzed the characteristics of image data of bighead fish, and proposed two problems to be solved urgently: network model selection, data migration, etc.Therefore, this paper proposes an automatic bighead carp traceability algorithm based on deep learning to solve the existing problems, and the accuracy of the algorithm model can reach 96.865% in the experimental test.In this paper, aiming at the problem of model selection, the mainstream deep learning framework networks at home and abroad are studied. By comparative analysis, the Densenet network is selected. Through the Densenet network model, the eigenvalues learned at each layer of the convolutional neural network can be transmitted back, and the initial effective features of learning can be maintained in the long-term learning process.The efficiency of feature extraction can be improved, and the learning cost can be greatly reduced.To solve the problem of image data migration of bighead fish, this paper adopts the idea of transfer learning and decompositions the training model into two steps: online training and offline training, so as to continuously learn the input characteristics of bighead fish, so as to ensure that high accuracy can still be achieved in the waters with different nutritional types.
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Application of improved NSGA2 algorithm in aero piston engine assembly

Abstract: (1780) HTML (0) PDF (0.00 ByteKB) (0)

Aiming at the replication phenomenon of individual components and parts in the selective assembly of complex mechanical products,this paper proposes a new evaluation index of solution set:population evenness, an elite reserved strategy of the offspring based on the combination of population evenness and degree of congestion is proposed，in order to improve the multi-objective optimization NSGA2(Non-dominated Sorting Genetic Algorithm-2) algorithm.With assembly qualified rate and assembly precision as the quality evaluation index, a multi-objective optimization model for selective assembly is established. Use the nearest neighbor search operator to overcome the deficiencies of the local search capability of the NSGA2 algorithm. Taking the assembly of a certain type of aircraft piston engines as an example, the optimization result is represented by the Pareto boundary set. The result shows that the diversity and astringency of the non-dominated solution sets (non-dominated solution sets) are obtained after the algorithm is improved.
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Fault diagnosis of centrifugal blowers based on multi-source information fusion and ADCNN

Zhang You, Li Congbo, Lin Lihong, Wang Rui

Abstract: (1783) HTML (0) PDF (0.00 ByteKB) (0)

The fault information of the single sensor signal is limited in the process of centrifugal blower fault recognition, and the traditional convolutional neural network (CNN) has poorer feature extraction abilities when processing multi-source high-dimensional data. To address this problem, this paper proposes a fault diagnosis method based on multi-source information fusion and adaptive deep convolutional neural network (ADCNN) for centrifugal blowers. Firstly, data-level fusion of multi-source homogeneous information of centrifugal blower is realized based on correlation variance contribution rate method, and the multi-source information fusion framework is established. Then, ADCNN is used to adaptively extract the features of heterogeneous information and complete feature fusion, an ADCNN fault diagnosis model that integrates multi-source information is constructed. Finally, the proposed method is applied to the fault diagnosis of centrifugal blower rotor and compared with the traditional fusion method, CNN, BPNN, SVM. The experiment results show that the proposed method has superior diagnosis accuracy and robustness than other methods.
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Denoising method of pipeline leakage signal based on EMD combined with DFA and wavelet transform

Wang Dongmei, Zhu Lijuan, Yue Jikang, Lu Jingyi

Abstract: (721) HTML (0) PDF (0.00 ByteKB) (0)

An improved Empirical Mode Decomposition（EMD）adaptive denoising algorithm based on Detrended Fluctuation Analysis (DFA) and wavelet transform (WT) is proposed. The noisy signal is adaptively decomposed into several Intrinsic Mode function (IMF) components by EMD, the scale index of each IMF is calculated by DFA, and the low-frequency useful components with long-range correlation are adaptively selected, the high frequency components are processed by WT. Finally, the selected low-frequency useful components and the high-frequency components after wavelet processing are used to reconstruct the denoised signal. Theoretical analysis and experiments show that the output signal-to-noise ratio of EMD-DFA and wavelet denoising methods after denoising are 12.3458dB and 13.7369dB, respectively.Compared with the single denoising algorithm, the output signal-to-noise ratio of the improved algorithm EMD-DFA-WT is 14.4513dB, and the signal-to-noise ratio is significantly improved, which effectively eliminates the noise in the leakage signal of the natural gas pipeline, highlights the signal characteristics, and achieves the purpose of noise reduction.
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Capturing high-level information recommendation algorithm with graph neural network

Liu Lihui, Sun TianHao, Xie Hong

Abstract: (960) HTML (0) PDF (0.00 ByteKB) (0)

The session-based recommendation task is about predict the user's next action based on an anonymous session. Existing approaches all make prediction by analyzing the current session, ignoring relevant transitions between each sessions the user historically made. Therefore, a recommendation algorithm based on graph neural network to capture higher order information is proposed. Firstly, learning the embedding vector of the item by aggregating information from local neighbors as well as higher order neighbors. Secondly,capturing the short-term and long-term interest with attention mechanism. Finally generate ranking score for predition. Experimental results on real data sets Yoochoose and Diginetica show that the proposed algorithm significantly improves the performance of the recommendation system compared to exisiting session-based recommendation algorithm.
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Reservoir lithology identification method based on differential evolution and XGBoost algorithm

han jian, wan chuan, cao zhimin, guo ying, li lin, daun chaohui

Abstract: (720) HTML (0) PDF (0.00 ByteKB) (0)

Using logging data to identify stratum lithology is a key link in petroleum exploration engineering. The lithology classifier based on machine learning has become a current research hotspot due to its excellent performance. Aiming at the problem that existing methods rely too much on relevant personnel's parameter adjustment experience, combined with the strong robustness of the XGBoost integrated classifier and the fast search ability of the differential evolution algorithm, a machine learning lithology identification method that can automatically adjust parameters is proposed. Differential evolution iterates the parameter population of XGBoost classifier to obtain the global optimal lithology recognition model. Based on the actual logging data of Daqing Oilfield, comparative experiments on lithology identification based on BP network, Randomforest, XGBoost have been carried out. The results show that the proposed method has good performance in overall accuracy, stability and recognition accuracy of each sub-category.
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Prioritized multi-task method of iteratively successive projection

Abstract: (2171) HTML (0) PDF (0.00 ByteKB) (0)

Compared with traditional non-redundant robots, redundant robots have higher flexibility. In order to make full use of the robot"s redundancy, tasks need to be inserted and removed, so that the robot can complete complex tasks in an unstructured environment. However, the robot velocity would be discontinuous during the task state switching. In response to this problem, this paper is based on the iteratively successive projection mechanism, a iteratively successive projection multi-task priority algorithm is proposed, which can ensure the continuity of joint velocity as tasks switch between inactive and active states, so as to ensues low priority tasks as much as possible within the ability of redundancy. At the same time, based on Lyapunov"s stability theory, the stability of the proposed iteratively successive projection multi-task priority algorithm is proved under the condition that the number of iterations tends to infinity. The trajectory tracking task of the six-bar planar manipulator in the presence of obstacles is simulated, which verifies the continuity and stability of the proposed method.
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Optimization analysis of particle swarm algorithm in motion simulation

WANG Hui, LIU Yingtao

Abstract: (621) HTML (0) PDF (0.00 ByteKB) (0)

To solve the problems of conservative parameter setting, limited motion space, and insufficient simulation fidelity of the classic washout algorithm of the flight simulator. Based on the perception principle of the human vestibular system, the bandpass filtering shunt was introduced to redesign the structure of the classic algorithm, and the particle filter algorithm (PSO) was used to optimize the natural cut-off frequency of each channel filter of the washout algorithm before and after the structural improvement. Then, a joint simulation model is established in Matlab / Simulink. The results show that the two algorithms optimized by PSO have benign changes in perceived phase error and range of motion, and the improved washout algorithm has more obvious effects and better parameter optimization performance, effectively improving the dynamic fidelity of the flight simulator.
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Investigation on the tribological properties of MRF for traction elevator magnetorheological brake

Abstract: (2125) HTML (0) PDF (0.00 ByteKB) (0)

For the existing magnetorheological fluid(MRF) does not apply in tractive elevator magnetorheological brake, studying the tribological performance of MR fluid is critical, related to the brake effectiveness. Four kinds of MRF was prepared with graphite, grease of silicone fluid for extra additives. Simulation of MRF in elevator transmission device by four-ball test machine, recording the friction coefficient changing of MRF, the size of wear scar was observed and measured by image microscope. The rheological properties of MRF before and after friction experiment were measured by rheometer, and the influence of friction and wear on performance of the MRF in the device was analyzed. Test and analysis results shows that the additive can reduce the friction of MRF to a certain extent, the rheological properties are increased after friction, the MRF with 0.5% graphite has low zero-field viscosity, high yield shear stress, and good stability, which is suitable for the MRF of traction elevator brake.
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Iterative learning perimeter control method for traffic sub-region considering disturbances

wangkun, yanfei

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Aiming at the problem of urban perimeter control, an iterative learning perimeter control method for traffic sub-region considering disturbances is proposed.Firstly, a discrete macroscopic traffic model is established by introducing disturbance term into the vehicle balance equation of road network.Secondly, based on the repeatability of macroscopic traffic flow, the iterative learning control strategy of boundary intersections is designed, and the tracking error of the system is proved to converge to a boundary under the action of bounded disturbance.Finally, taking the actual road network as an example, the simulation results show that the iterative learning perimeter control method considering disturbances can effectively restrain the influence of different degrees of disturbance on the road network performance and improve the traffic condition of the road network.
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Research on reinforcement learning autonomous vehicle decision making at intersection based on ARMA speed forecasting model

Liu Yonggang, Yu Zhicheng

Abstract: (954) HTML (0) PDF (0.00 ByteKB) (0)

In order to solve the problem of autonomous vehicle decision and control at an unsignalized intersection, this paper studies the confluence condition of two vehicles at a two-way single-lane intersection. The method of reinforcement learning is used for the decision and control of autonomous vehicle to establish the mapping relationship between vehicle state space and action space. Aiming at the problem that the vehicle speed setting is too simple in the present study, the data collected in the actual scene was used as the trajectory information of the environmental vehicle to construct the scene model. Based on the autoregressive moving average model, the vehicle speed of environmental vehicle is predicted. Combining with the autonomous vehicle and the predicted environmental vehicle speed timing information, the forward decision-making model is established to calculate the reference speed, and the reference speed is introduced to construct the reinforcement learning reward function to accelerate the training convergence speed. The results show that the enhanced learning model has a fast convergence speed, and the trained agent can safely pass through the intersection when gambling with environmental vehicles with different driving styles, this paper provides a reference for autonomous vehicle safety decision-making and control at no-signal intersection.
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Damage Mechanism of PBX Explosives Based on Three-Dimensional Meso-Structure

GongQin, Liu Zhan-fang

Abstract: (741) HTML (0) PDF (0.00 ByteKB) (0)

In order to understand the influence of microstructure difference and thermal effect on the damage of PBX explosive. The damage evolution mechanism of PBX with different microstructure under thermal load is analyzed by using Voronoi method to establish a three-dimensional meso model, considering the elasto-plastic properties of particles, the elasto-viscoplastic properties of binder and the interfacial cohesion constitutive relationship. The results show that the interface is not easy to be damaged when the temperature is raised, and the binder with small shrinkage hinders the shrinkage of particles when the temperature is lowered, resulting in the increase of the normal tensile stress between the interfaces, which is easy to cause interface damage. Increasing the content of binder is beneficial to reduce the damage degree of interface during cooling. When the binder content is similar, the more uniform the particle size is, the smaller the interfacial damage is. Under the action of low pressure, the damage changes from normal stress to tangential stress, and the damage degree decreases. However, when the pressure is too high, new damage occurs at the interface.
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Adaptive meshless method for thermoelastic problems with concave convex boundary

Yanglan, jiankailin

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In order to solve the plane unsteady and quasi-static coupled thermoelasticity problems with concave convex boundary shape, the element free Galerkin method (EFG) is used to solve the problem, the Moving least square method（MLS） is used to construct the shape function, the Lagrange multiplier method is used to deal with the essential boundary conditions (the first kind of boundary conditions), the Voronoi adjacency criterion and the posteriori error formula are introduced to adaptively optimize the subsequent results; A new EFG adaptive model for unsteady quasi-static and coupled thermoelasticity problems is constructed. The temperature field and displacement field distribution in the planes with smooth and concave convex boundary shape are calculated under two-dimensional mixed boundary conditions, respectively. And the results are compared with those of finite element method. The difference between the results of finite element method and meshless method is characterized, and the effectiveness and accuracy of EFG for unsteady quasi-static thermoelasticity coupled problem are verified
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Black start optimization strategy for island microgrid with large number of inductive load

Lin Jiayang, Zhou Weihao, Yi Yongli, Wu Kunming, Tang Liangchun, Chen Minyou

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Island is prone to extreme weather such as typhoons. Under extreme natural conditions, it is easy to cause the operation of the island’s microgrid to malfunction, and even cause the island’s microgrid to collapse. When the island microgrid collapses, the black start is required to restore the entire system. However, due to the particularity of the island microgrid load, a large number of inductive loads based on asynchronous motors will affect the system voltage during the black start. In order to improve the efficiency of black start of island microgrid, this paper proposes a black start optimization strategy of island microgrid based on virtual active load. First, propose a black start power startup sequence optimization model, use the entropy weight method to evaluate the black start ability of different DGs, and restore DGs in time steps according to their evaluation value from high to low; then, propose load recovery at each time step The optimization model takes the maximum load recovery amount and the maximum load recovery importance as the goal, and uses the PSO algorithm to solve the corresponding load optimization model; then, the path recovery optimization model of each time step DG and load is proposed and the Prim of the minimum spanning tree is used Path optimization algorithm to solve. In addition, this paper also proposes a virtual active load construction method. In the black start process, it is considered that the inductive load and the parallel compensation capacitor are equivalent to the active load, thereby improving the black start success rate. Finally, the simplified 19-node microgrid structure is used as the test system for simulation verification. The simulation results show that, compared with the black start strategy that does not consider optimization, the method in this paper increases the load recovery by 33.8% during the black start process. The importance of restoring the load, and the total path restoration time is reduced by 54.9%, which improves the efficiency of the black start of the island microgrid. In addition, according to the virtual active load construction method proposed in this paper, the simulation results show that when the reactive power provided by the parallel capacitor is sufficient, the impact of the inductive load on the system voltage can be significantly reduced during the black start process.
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A Low-complexity Soft-Output Signal Detection for Uplink Large-scale MIMO

Shen Dong, zhao Dan, Li Qiang, Di Jing

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Based on the high dimension of the channel matrix and the complexity of the received signals, a hybrid iterative algorithm signal detection on uplink for large-scale MIMO systems is proposed, which combines adaptive damped Jacobi (DJ) algorithm and conjugate gradient (CG) algorithm. Firstly, conjugate gradient algorithm is used to provide effective search direction for adaptive damped Jacobian iterative algorithm. Then, Chebyshev method is proposed to eliminate the influence of relaxation parameters on signal detection to reduce the complexity of the algorithm and accelerate the convergence speed. Finally, the soft information is approximately solved by using the bit likelihood ratio in channel coding and decoding. The simulation results show that the hybrid iterative algorithm converges quickly and approximately achieves the best MMSE detection performance under a small number of iterations, and the algorithm complexity is far lower than that of MMSE algorithm.
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Characteristics of icing on transmission lines under natural conditions

Gao Jin, Jiang Xingliang, Guo Sihua, Han Xingbo, Zhang Qi

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The icing of transmission lines seriously threatens the safe of power grid. The icing process of transmission lines is complicated and there are many influences. The accurate understanding of the law of icing is the basis for the establishment and optimization of a icing numerical model. Based on natural icing tests, the tests of different kinds of conductor are carried out on Xuefeng mountain natural icing test base, and the influences of conductor diameter, conductor surface treatment, icing type and torsion on icing process are studied. The characteristics of icing on conductors with different diameters are analyzed by calculating the water droplet collision efficiency. The results show that under the natural environment, the wind velocity is the key factor which determines the rime shape on transmission lines. Meanwhile, the icing thickness increases nonlinearly with time, the smaller the conductor diameter, the faster the icing thickness increases. The conductor torsion makes the leeward side of conductor changes to the windward side, which increases the icing rate. When the icing type becomes glaze, in addition to the windward wing ice, there are more likely icicles freezing under a conductor, as a result, the ice structure becomes more complex.
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Study on the mechanism of secondary dewatering for fine thickened tailings that contains admixture

YANG Gang-feng, WANG Yong, WU Ai-xiang

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When the tailings still do not reach the expected concentration under the traditional dewatering process conditions, the addition of admixture is an effective means to achieve secondary rapid dewatering. For the problem that the copper ore tailings are fine and the bleeding ability is poor, and the concentration is still not up to standard after dewatering by the deep cone thickener, the secondary dewatering experiment is carried out by adding the A-type admixture and the B-type admixture, and the admixture is not added as the control. The experimental results showed that the bleeding amount of slurry with admixture was significantly greater than that without admixture for 1h and 2h. With the increase of bleeding time, the bleeding amount of slurry with admixture and without admixture was basically equal at 4h. Through the regression equation of dewatering mass fraction and dewatering time in three cases, the mathematical model of secondary dewatering of concentrated tailings was obtained, the relationship between the secondary dewatering mass fraction and the dewatering time is exponential function. Finally, the mechanism of rapid dewatering and structural strengthening of tailings by admixture was analyzed. The admixture not only increased the dewatering concentration of tailings, but also increased the stability of tailings, which has potential engineering application value.
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Secure Routing Selection Algorithm Based on Game Theory in MEC-D2D Communication Systems

Yuhao, LI Kui, XIANG Ling, LI Zhen-wei, LIU Jiang, DONG Ya-wen, FENG Wen-jiang

Abstract: (613) HTML (0) PDF (0.00 ByteKB) (0)

This paper proposes a secure routing algorithm based on game theory to optimize routing strategies for the problem of malicious nodes that intend to spread malware in a communication system that combines device-to-device and mobile edge computing, and verifies the feasibility of the algorithm. The algorithm assumes that the nodes in the device-to-device communication system are equipped with anti-malware controls, and select the safe routes using game theory based on the detection cost, routing QoS and the joint detection capability of the malware to taking into account the security of packet transmission and the QoS. Simulation results show that the designed secure routing algorithm can take into account the security and QoS of data packet transmission.
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Research on electro-hydraulic control system for automatic anti-sticking of coal mine drilling rig

Dongmin Li, Shiming Zhu, Yuanzhi Zhao, Tong Wang, Peisi Zhong, Shangfei Xia

Abstract: (747) HTML (0) PDF (0.00 ByteKB) (0)

Due to the complex and changeable geological conditions of the soft coal seam, sticking accidents often occur during the drilling construction of the drilling rig, which greatly reduces the work efficiency and seriously threatens the personal safety of workers. In order to solve the above problems, the influencing factors of sticking are analyzed, the rotary pressure of drilling rig is used to describe the state of sticking, and the threshold of slewing pressure sticking is set. According to the working principle of drilling rig and sticking mechanism, the anti-sticking hydraulic circuit based on the Load Independent Flow Distribution System(LUDV) is established, the automatic anti-sticking controller is established by PID and signal selector, and the Seeker Optimization Algorithm(SOA) is used to adjust PID parameters. The system simulation test is carried out by using AMESim, and the results show that when the rotary pressure reaches 200bar, the drilling rig automatically pulls back; when the rotary pressure reaches 220bar, the drilling rig slewing pressure remains stable and a large slewing power is maintained to overcome the external load resistance and avoid sticking accidents, which verifies the effectiveness of the automatic anti-drilling electro-hydraulic control system.
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Functional Type Identification method of Residential Room based on simulated annealing algorithm and SVM

LI Changhua, YING Jun, LI Zhijie

Abstract: (944) HTML (0) PDF (0.00 ByteKB) (0)

BIM models have played a central role in the construction industry in recent years and become an active research direction for intelligent buildings and intelligent cities. Room is an important part of BIM model, and the perfection of room data is of great significance to improve the automation, efficiency and accuracy of BIM applications such as compliance inspection and spatial analysis. to the problem that insufficient room information in the BIM model leads to the difficulty of identifying the room, a room function type identification method combining simulated annealing and SVM is proposed and verified on the residential model set. first, based on the Revit platform secondary development technology, the room shape feature parameters are obtained first, and the main parameters of the SVM model are optimized by expanding the spatial syntactic variables such as connectivity, control, average depth, integration, intelligence. finally, the accuracy of the optimized SVM model is verified on the validation set. experimental results show that compared with the algorithms proposed in other similar literatures, the accuracy of the proposed algorithm can reach 95.59%, which is better than that of similar algorithms. experiments on four UCI datasets verify the stability and effectiveness of the classification model.
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Dynamic routing algorithm for Energy-Harvesting Wireless Sensor Network

lixin, Gu Zhengfeng, Li Baoqing, Yuan Xiaobing

Abstract: (653) HTML (0) PDF (0.00 ByteKB) (0)

Energy-harvesting technology enables sensor nodes to collect energy from the external environment, which greatly alleviates the energy consumption problem of wireless sensor network. In order to make full use of the collected energy and improve the network performance, a dynamic energy harvesting wireless sensor network routing algorithm is proposed. The algorithm can dynamically adjust the number of cluster heads in each round according to the average residual energy and collected energy of the network to ensure efficient use of collected energy and avoid node energy overflow or waste. In the cluster head selection, the residual energy, the collected energy and the distance between nodes are taken into consideration at the same time, so that the cluster head nodes with better energy status can be evenly distributed in the network. The simulation results show that the proposed algorithm can effectively balance cluster heads distribution, and is superior to other existing algorithms based on energy-harvesting model in terms of average energy efficiency and throughput.
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Safe and green exploitation model and demonstration projects of deep outburst mine based on the integration of gas control, extraction and utilization

zhangjianguo, wangman, yuanmiao, liuqingjun, lideng, wangxiaochuan

Abstract: (769) HTML (0) PDF (0.00 ByteKB) (0)

This paper analyzes the main problems in gas control and recycling in deep outburst mines in China, and summarizes the development status of gas control, gas extraction, gas utilization and heat damage control. Taking Shoushan No. 1 mine as an example, a closed loop system architecture of gas treatment - gas extraction - gas power generation - centralized refrigeration - heat damage control is proposed to realize safe, efficient and green development of deep outburst mine. The comprehensive gas control technology of "one side and many lanes" in coal seam with single mining height and low permeability outburst in shoushan mode is studied. The combined operation process of gas power generation equipment and refrigeration equipment is analyzed to realize effective treatment of heat damage in deep Wells. The demonstration project of power grid connection and mine cooling in Shoushan No.1 mine was established to realize the unification of comprehensive management and recycling of gas resources, and to form a safe, efficient and green development mode of deep outburst mine, which can provide reference for similar mine development in China.
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Analysis and algorithm optimization of contact bounce behavior of contactors

HUANG Kepeng, WANG Fazhan, ZHAO Mingji, LI Yafeng, OU Daquan

Abstract: (917) HTML (0) PDF (0.00 ByteKB) (0)

In order to obtain the law of contact bounce, the two degree of freedom piecewise coupled differential equation of contact system is simplified and evaluated. Using ADAMS view to establish the prototype model of AC contactor, combining the user-defined genetic algorithm with the dynamic analysis software ADAMS, selecting the mechanical parameters that have a great impact on the bounce time as the design variables, and optimizing the contact system design. The results show that the bounce time of contactor contact optimized by genetic algorithm is reduced by 89%. Finally, the experimental results and simulation errors of the laser rangefinder are less than 2%. The superiority and feasibility of the optimization design method based on genetic algorithm and ADAMS software in the optimization of contactor parameters are verified. The research results provide a new method for further comprehensive optimization of contactor prototype.
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Water-rock interaction simulation of artificial recharge in the groundwater over-exploited area of the Hutuo river basin

gengxinxin, zhangfenge, zhupucheng, malinna, chenli, guochunyan

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The water-rock interaction in the recharge water and groundwater mixed zone of aquifer under artificial recharge is the key process that determines the evolution of groundwater quality and leads to the chemical clogging of aquifer. To study the effect of artificial recharge on the groundwater quality evolution in the groundwater over-exploited area of the Hutuo river basin, took the groundwater artificial recharge site in Shijiazhuang as an example , the Shijin irrigation canal water were used as the recharge water ， the laboratory experiments and reverse hydrogeochemical simulation were used to reveal the mechanism of water-rock interaction of surface water and groundwater mixed zone in the aquifer. The results showed that the evolution characteristics of TDS in the mixed zone was firstly increasing and then slowly decreasing, if the proportion of surface water mixed with water was larger and the particle size of medium was smaller, the variation amplitude of TDS is larger. Mixing action, carbonic acid balance, dissolution-precipitation and nitrification controlled the change of main ion concentration, whereas the concentration of K+, Ca2+and SO42- were mainly controlled by solution-precipitation, the concentration of Na+, Cl-, HCO3-, NO3- is mainly controlled by mixing, and the concentration of Mg2+ is mainly controlled by cation exchange. In the water-rock reaction, the dissolved minerals include anhydrite albite, K-feldspar and halite, whereas the precipitated minerals include calcite, calcium montmorillonite and quartz. Moreover, in the larger the proportion of surface water, the finer the particle size of medium, and the more the calcite precipitation, indicated that the risk of carbonate chemical clogging is high in the aquifer with fine particle size, as the surface water was the recharge source. The results can provide scientific basis for the safe and efficient artificial recharge engineering.
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A CDR equipped with a charge pump featuring automatic current switch

Yuxuan-WU, Fangxu-LV, Jianye-WANG

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This paper designs a fast-locking and low-jitter clock and data recovery (CDR) circuit which can be applied to a 28Gb/s high-speed serial receiver. Via theories-based derivation, we built a mathematical model between loop parameters and loop stability, designed circuits and optimized the loop parameters on that basis. In order to solve the problem that the jitter performance and locking time of the clock cannot be achieved at the same time, a charge pump featuring automatic current switch is installed in a circuit structure where the proportional path is separated from the integral path. In this way, automatic adjustment of the loop bandwidth is accomplished, which equips the loop with low jitter and fast locking. Using Matlab simulation, we identified the factors that influenced the loop stability and validated our mathematical model. Through the Cadence Sepctre simulation, the locking takes about 450 ns and the value of the jitter peak is 2.3 ps. Compared with a CDR equipped with a traditional charge pump, the new CDR has shortened the locking time by 55% and reduced the jitter by 52%.
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Experimental study on complex resistivity test of coal

LEI Dong-ji, zhoumeng, menghui, zhao chenguang

Abstract: (759) HTML (0) PDF (0.00 ByteKB) (0)

The purpose of complex resistivity measurement of coal in laboratory is intended to provide reliable data of complex resistivity for further field application. There are many factors that affect the measurement accuracy of coal complex resistivity, among which electrode plate is one of the most important factors. The selection of electrode material, thickness and size of electrode plate will affect the result of coal complex resistivity measurement, so the change of electrode plate is of great significance to the accuracy of measurement parameters. In this paper, the complex resistivity of three kinds of electrode materials with different thickness is measured by using the copper material with better conductivity as the electrode plate. The influence of the thickness of the electrode plate on the induced polarization effect is analyzed. The influence of five kinds of electrode plates with diameter of 1cm, 2cm, 3cm, 4cm and 5cm on the measurement of the complex resistivity of coal is tested. The Cole-Cole model is used for data fitting. The conclusions are as follows: (1) the polarization effect of the electrode plate itself and the bonding degree between the electrode plate and the end face of the coal sample are the main factors affecting the measurement error of the complex resistance of the coal sample, and the error of the conductive copper paper is the smallest among the three electrode materials; (2) for the same coal sample, the change of the area of the electrode plate only has a great influence on the amplitude of the complex resistance, and the influence on the induced polarization of the coal sample can be ignored. In this paper, the importance of electrode material and contact area is considered to improve the accuracy of the measurement of the complex resistivity of coal samples in the laboratory, which lays a foundation for the research of the experimental method of the complex resistivity of coal and the field application of the complex resistivity method.
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An On-line Measurement System for Contour Error of Large Cylindrical Parts

tianshun, xu mingzhu, zhangnaifan, jin xiaoqing, zhangjisheng

Abstract: (793) HTML (0) PDF (0.00 ByteKB) (0)

An on-line measurement system was developed for the contour error measurement of large cylindrical parts. The system is controlled by single-chip microprocessor + PC, with two synchronously rotating rollers driving the rotation of the measured parts, whose surface profile is measured through a non-contact sensor. The companion algorithms for evaluating the roundness error was programmed to extract the contour error value of each equinox of the workpiece surface, and the contour error curve was plotted. Theoretical analyses and experimental results show that the system is feasible to carry out the on-line measurements of large cylinders, and may be of value for various engineering applications.
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Study on CO background concentration screening and spontaneous combustion prediction of ultra long coal roadway

li teng, LI Zong-xiang, Wang ji ren, YANG Fu qiang, ZHANG CHun hua, jiajinzhang

Abstract: (650) HTML (0) PDF (0.00 ByteKB) (0)

To achieve the early prediction of the latent fire source of coal spontaneous combustion in the long-distance spontaneous combustion coal seam double coal roadways, it is proposed to jointly utilize the Data Analysis Method of the coal mine monitoring system which can early predict and forecast the latent spontaneous combustion fire and improve the reliability, while it still keeps and ameliorates the Gas Analysis Method. In order to single out the fluctuations of CO generated by the exhaust gas of diesel vehicles in the coal mine, it is introduced the background of CO concentration, and the basic assumption is made: in one day, one or more diesel vehicles can finally be found intermittent moments in the busy work (monitoring time) ), then given the background CO concentration in a day which is determined by the minimum monitored value of CO. Taking the shortest natural combustion period as the examination period, and the continuous increase of CO concentration as the criterion of judgment method, we give two prediction and prediction models of regression trend method and integral method, furthermore,the forecasting and forecasting is supposed to divide into three levels, namely, key inspection, enhanced inspection and the reason query. In combination with Hong Qingliang Coal Mines, the lowest average rate of increase of CO, k1^*= 0.607 ppm/d is obtained. Based on the above-mentioned reliable predicting and forecasting methods, the long-distance roadway will be changed the comprehensive inspection every day to the targeted key inspection.
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The Development of Wire Arc additive Manufacturing Technology in Ti-6Al-4V Alloy

XIA Yu-feng, TENG Hai-hao, ZHANG Xue, ZHENG De-yu, CHEN Yan-hong

Abstract: (871) HTML (0) PDF (0.00 ByteKB) (0)

Ti-6Al-4V titanium alloy has the characteristics of low density, stable structure and high strength at high temperature. It is widely used in the manufacturing of key parts of aviation industry such as wing beam, landing gear support rib and so on. The research of arc fuse additive technology began in 1980s, which has the advantages of high forming efficiency, high utilization rate of raw materials and simple equipment. At present, the technology of Ti-6Al-4V alloy arc fuse additive has been widely studied and some achievements have been achieved. This paper summarizes the research and application of Ti-6Al-4V alloy arc fuse additive technology at home and abroad, and analyzes the microstructure, mechanical properties and control technology of the titanium alloy after processing. Finally, in view of the current bottleneck of the process, the research direction is prospected.
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Transient electromagnetic wave field transformation imaging technology for coalbed methane enrichment mine goaf

Qiu Hao

Abstract: (689) HTML (0) PDF (0.00 ByteKB) (0)

Mining-induced fractures and goaf are closely related to mine coalbed methane seepage and occurrence. Accurate detection of goaf and mining-induced fractures is the basic work of coalbed methane mining. Based on wave field transformation theory, nonlinear damped least squares algorithm is used to calculate the wave field transformation integral equation. Whole-space response correction and wave field data processing are carried out . The working method of synthetic aperture imaging in coal mine underground roadway is expounded. Numerical simulation of 3D goaf wavefield imaging model are carried out.Engineering application were carried out for advanced detection and coal mining face detection methods in Jincheng coalbed methane mining area. .This technology obviously reflects the water-rich boundary of the mining-induced fractures and goaf. Wavefield transformation imaging technology can extract electrical boundary information in transient electromagnetic data. The wave field result can reduce the adverse effects of volume effect on the goaf and mining-induced fractures interpretation. Wave field transformation imaging technology is suitable for detection of goaf and mining-induced fractures. The results of drilling verification are consistent with the results of wave field imaging and apparent resistivity analysis.
1
Temperature-resistance property of graphene/epoxy nanocomposites temperature sensor

Abstract: (3175) HTML (0) PDF (0.00 ByteKB) (0)

With the increasing performance requirements of the temperature sensor, to develop a new high-performance temperature sensor is of great significance .With graphene as the nanofiller and epoxy resin as the matrix, various of graphene/epoxy nanocomposite with different graphene addition were prepared by ultrasonic and planetary stirring. Electrodes were attached at both ends of the graphene/epoxy nanocomposite sheet to form the temperature sensor. The effects of graphene addition on the temperature-resistance properties of the nanocomposites were investigated at the temperature range of 30 °C-100 °C. The results showed that the resistance of the temperature sensor specimen decreased linearly with the increasing temperature, which demonstrated a negative temperature coefficient (NTC) effect. In addition, it is found that the higher the graphene content, the magnitude of the resistance change was smaller. After three thermal cycle treatments, the temperature-resistance relationship of the sensor tends to be stable.
1
The coagulation effect and floc characteristics of different forms of algae

Yao Juanjuan, Gong Dan, Fang Yanjuan, Zhang Zhi

Abstract: (996) HTML (0) PDF (0.00 ByteKB) (0)

The coagulation effects and floc characteristics of M.aeruginosa, Synedra and Anabaena were studied, respectively, by using ferric chloride and aluminum sulfate coagulants. The results show that the ferric salt has better coagulation and removal effect on the three algae species than that of aluminum salt, and the optimal dosage of ferric salt coagulation is also greater than that of aluminum salt under different dosages of ferric and aluminum salts coagulant.The M.aeruginosa has the worst coagulation effect, and Synedra has the best under different dosages of ferric and aluminum salts. Compared with the use of aluminum salt, the three algae flocs coagulated by iron salt are denser and have larger fractal dimension. The fractal dimension value of Synedra is the largest(the maximum value:1.72) and that of M.aeruginosa is the smallest(the maximum value:1.17), indicating the effect of algae morphology on the flocs structure. The particle size(d50) of the three algae species when coagulated with ferric salt are larger than that of the flocs using aluminum salt, and the strength and recovery factor of the ferric salt flocs are smaller than that of the aluminum salt flocs. The maximum value of d50 of M.aeruginosa floc(632μm) is smaller than that of Synedra floc (765μm) and Anabaena floc(777μm) when using ferric salt. Synedra has the largest recovery factor of 26.54%, and Anabaena has the smallest recovery factor of 11.04% when using ferric salt. When the three algal flocs reach the isoelectric point, the dosage of ferric salt is greater than that of aluminum salt.The zeta potential of algal floc can be used to analyze the dosage corresponding to the optimal removal rate of algae coagulation. The M.aeruginosa flocculation is mainly electroneutralized, while the adsorption bridge and netting may play a more important role in the flocculation of Anabaena and Synedra.
1
Analysis and design of continuously variable transmission mechanism with non-circular gear

Abstract: (2915) HTML (0) PDF (0.00 ByteKB) (0)

On the basis of the multi-segment function construction method, the reproduction design of non-circular gear pairs with preset time-varying transmission ratio has been proposed. Combined with the practical application of non-circular gear pairs in industry, a continuously variable transmission mechanism with non-circular gear pair has been presented. The influence of basic parameters of non-circular gear with output transmission ratio is discussed. Based on SolidWorks 、Adams and other software, the simulation model of this continuously variable transmission mechanism is established. The output characteristics are verified by the simulated motion in ADAMS.
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Development and optimization of abrasive water-jet directional slitting machine for coal mine

LU Yi-yu, QIN Xu-qian, TANG Ji-ren, ZHANG Wen-feng, LING Yuan-fei, LI Qian

Abstract: (760) HTML (0) PDF (0.00 ByteKB) (0)

The N00 method is a highly efficient and resource saving mining method, witch a key step is to quickly separate the gob roof and the roadway roof by making a slit between them. Based on the water jet theory and technology, a new idea of using abrasive jet directional cutting roof is proposed. The structural composition and working principle of the abrasive jet directional cutting system are studied, and the water jet nozzle, cutting nozzle, orienter, conveyor, abrasive are designed. Through experiment, the working parameters of the abrasive jet directional cutting has been optimized, and the roof cutting test was carried out on the S1201-II working face of a mine in Shaanxi. The results show that under the conditions of jet pressure 25MPa, nozzle diameter 1.5mm, abrasive type yellow sand / quartz sand, abrasive concentration 3.5%, cutting speed 4.4mm / s, the developed system is able to make slits at the same time in 4 holes of 7000-8000mm deep within a cycle time (50min).
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AAHT-Based Truck Load Simulation Model and Its Influence on Bridge Fatigue Damage

LIU Lang, YANG Hong

Abstract: (715) HTML (0) PDF (0.00 ByteKB) (0)

The recorded traffic data shows that traffic loads have been increasing. In this study, based on the long-term health monitoring data collected from Anhui Province, the annual average hourly traffic (AAHT) is defined to take into account the periodical and seasonal change of traffic volumes, furthermore, an autoregressive moving average model (SARIMA) is established to simulate truck loads in the future. At the same time, several truck load models are developed with the statistics of the key parameters of truck data, and then loaded one by one on the finite element model of a T-bridge, to calculate the fatigue damage induced by the non-stationary increases of truck traffic. The results show that the AAHT-based SARIMA model is accurate and efficient for predicting traffic loads, moreover, the non-stationary increase of traffic loads will significantly jeopardize bridge structures due to the fatigue damage caused. Specifically, the fatigue damage will be increased by about 50% when considering this kind of non-stationary increase.
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Design of a new dehydration tube based on bionics and its dehydration law

ZHANG Aiqing, WU Aixiang, WANG Yiming, LI Jinyun

Abstract: (470) HTML (0) PDF (0.00 ByteKB) (0)

The type of dehydration tube is one of the key factors influencing the dehydration technology of filling. The paper analyzes the water absorption model of plant roots, designs new dehydration tube and related test devices based on bionics, studies the dehydration efficiency, effect of the new dehydration tube and the dehydration law of unclassified tailings non-cemented filling. The test results show that the root-like design of the dehydration tube can increase the water passing area and reduce the seepage distance of the dehydration tube. Compared with the ordinary dehydration tube, the new type reduces the dehydration time by 20%, and the cumulative dehydration volume increases by 10.3%, which improves the dehydration efficiency. The tailings loss was introduced to evaluate the dehydration effect of dehydration tube, and the new type dehydration tube has a 45% reduction in tailings loss compared to the conventional dehydrating tube. The unclassified tailings non-cemented filling and the inner surface of the test device form a large number of uniformly distributed pore water-conducting zones, which is one of the reasons why the new dehydration tube can improve the dehydration efficiency. The dehydration process of the unclassified tailings non-cemented filling can be divided into three stages: rapid, steady and gentle flow zone. The steady flow zone is the key to improve dehydration efficiency.
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Solid Mechanical Simulation and Pore-scale Modelling of Reconstructed Carbon Felt for Vanadium Redox Flow Battery

XIAO Liu-Sheng, LUO Ma-Ji, ZHU Li-Jun, DUAN Kang-Jun, Roswitha Zeis, SUI Bang-Jie

Abstract: (775) HTML (0) PDF (0.00 ByteKB) (0)

X-ray computed tomography (XCT) reconstruction technique, finite element method (FEM) and pore scale modelling (PSM) were employed to investigate the displacement distribution and its effects on transport properties of vanadium redox flow battery (VRFB) carbon felt under compression at pore-scale. Contact, friction, extrusion and bending were considered between carbon fibers. Micro-structure of a carbon felt was reconstructed by XCT first, then the displacement distribution of the microstructure in 3D (X, Y and Z direction) with different compression ratio (CR) were investigated, and last the relationship between the displacement and transport properties was quanlificated. The results show that the carbon fibers’ displacement in the Z direction (through plane) under compression is more noticeable. As CR was increased to 30%, the displacement change in Z direction is -59~+5μm, and in XY directions (in-plane) is -25~+ 16μm, the diffusion coefficient of the vanadium ion in XY direction is decreased by 15.4%, and in Z direction is decreased by 24.2%. The conductivity in XY direction is increased by 102.1%, and in Z direction increases by 46.2%. As CR is increased from 20% to 30%, the diffusion coefficient and the conductivity change faster.
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Spatial Distribution Characteristics and Conditional Factors of Landslide Disasters in Mountain cities

wang xinsheng, teng degui, xie wei, nie wen, yu xin, chen jie

Abstract: (672) HTML (0) PDF (0.00 ByteKB) (0)

In view of the uncertainty of landslide disasters affected areas in mountain cities, the typical landslides in the central urban area of Chongqing are selected as the research objects. and the spatial distribution characteristics of historical landslide disaster points are analyzed using the nearest neighbor index, spatial hotspot detection and kernel density estimation methods; A landslide factor database was established with 12 influencing factors includes elevation, slope, aspect, landform type, geological lithology, soil type, soil erosion, rainfall, water system, land use, Normalized Difference Vegetation Index (NDVI), and population density. A neural network model was used to quantitatively analyze the contribution weight of each influencing factor, and the model was accurate using Receiver Operating Characteristic (ROC) curve assessment. The research results show that the historical landslide disaster points in the study area are clustered, and Yuzhong District, Shapingba District, and northern Banan District are the areas where the landslides are most concentrated. Among all the factors, population density, land use and rainfall occupy the highest weight, while the aspect and road are the lowest. The area value under the ROC curve (AUC) was 0.917, indicating that the model can accurately reflect the impact of landslide impact factors in the area.
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Research on Internal Temperature Field Distribution and Influencing Characteristics of Internal Pressure of Inverted Oil-Immersed Current TransformerJI Kunyu¹, LIU Yang², LI Bonan³, LI Xi³, HUANG Leifeng³, CHEN Ting¹

jikunyu, liuyang, libonan, lixi, huangleifeng, chenting

Abstract: (1105) HTML (0) PDF (0.00 ByteKB) (0)

The current transformer converts the large current in the primary system into a small current for secondary measurement and measurement protection in the power system. It has an indispensable effect on the stable operation and fault current measurement of the power system. During the online operation, the abnormal increase in gas of the oil inside the transformer caused by partial discharge, heat failure, etc., caused the internal pressure to increase sharply, which easily caused insulation damage and explosion. In order to study the internal temperature field distribution of the transformer and the influence factors of pressure changes, and to find the internal pressure surge failure in time, this paper uses ANSYS Fluent software simulation to establish a 220kV inverted oil immersed current transformer model, using finite element analysis and multiphysics coupling analysis The internal temperature field distribution law of the inverted oil immersed current transformer was obtained by other methods, and an experimental platform for the inverted oil immersed current transformer was established to verify the validity of the simulation. Meanwhile, the pressure online based on the MD-TPR transformer was designed. The monitoring device obtained the characteristics of the internal pressure influence of the transformer.
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Study on hybrid model of peridynamics and finite element method

qianwei, FAN Cun-xin, SHEN Feng, XIA Yi-bing

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Considering the advantages of peridynamics in simulating discontinuities and low computational cost of finite element method (FEM), In this paper, a new hybrid model was established by using the hybrid modeling method of peridynamics and finite element method.The model was set up by peridynamics theory in the region where cracks appear, and the other regions were modeled by eight node isoparametric elements. The truss element was used to connect the material points with the isoparametric nodes, and the interaction between material points could be regarded as the truss element. Finally, the stiffness of the element was integrated to realize the hybrid modeling of the two methods in the finite element frame system.The model does not need to introduce artificial damping, which improves the calculation efficiency. In addition,compared with the four node hybrid model, the hybrid model based on high order (eight node) isoparametric element and peridynamics has higher accuracy.can be applied to complex stress-strain problems.The validity of the method is verified by the numerical example, which provides a new idea to solve fracture problems.
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Adaptive tracking control algorithm for flexible power point of photovoltaic system considering dynamic environment

shiyonghao

Abstract: (999) HTML (0) PDF (0.00 ByteKB) (0)

A major problem related to the growing popularity of grid connected photovoltaic power generation is the operational challenges (such as overload and overvoltage) due to the variability of photovoltaic power generation. Flexible power point tracking (fppt) can limit the photovoltaic output power to a specific value to solve some integration problems. The traditional fppt algorithm based on disturbance observation has the problem of slow dynamics. Therefore, an adaptive fppt algorithm is proposed in this paper. The algorithm has fast dynamic characteristics under the fast changing environment conditions (such as cloud layer passing), while maintaining low power oscillation in the steady state. The proposed algorithm uses additional measurement samples under each disturbance to observe changes in operating conditions (such as solar irradiance). Then, the voltage step is calculated adaptively according to the observation conditions (such as transient or steady state) to improve the tracking performance. Finally, the simulation experiment on 3KVA single-phase photovoltaic grid connected system verifies the effectiveness of the algorithm in terms of fast dynamics and high accuracy under different operating conditions.
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Rolling bearings fault diagnosis of SVM optimized by surface-simplex swarm evolution algorithm

zheng meng fu, quan hai yan

Abstract: (675) HTML (0) PDF (0.00 ByteKB) (0)

Because the parameter optimization algorithm of support vector machine (SVM) has many control parameters and fall into the local optimum easily, and in order to realize diagnosis, rolling bearings fault diagnosis of SVM optimized by surface-simplex swarm evolution algorithm is proposed. First, surface-simplex swarm evolution (SSSE) establishes the particle's simple neighborhood search operator in a random way to reduce control parameters and the multi-role state search strategy to avoid falling into the local optimum. Then SSSE is applied to parameter optimization of SVM to realize fault diagnosis. In the test，the energy matrix of ensemble empirical mode decomposition(EEMD) of rolling bearing signal is used as the feature input to perform performance analysis and testing of the algorithm. The results show that the method not only effectively avoid the particles falling into the local optimal solution，but also reduce the control parameters, and can complete the signal diagnosis.
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Multi-source data fusion city 3D real-world modeling

xieyunpeng, lvkejing

Abstract: (1219) HTML (0) PDF (0.00 ByteKB) (0)

With the development of digital cities and smart cities, urban simulation has developed from two-dimensional to three-dimensional, and the requirements for urban three-dimensional real-world modeling have become higher and higher. Due to the high density and rapid change of urban features, traditional manual 3D modeling methods are inefficient and cannot adapt to the rapidly changing and changing urban environment. Therefore, UAV tilt photography technology is often used for fast 3D modeling, but UAV tilt photography method cannot solve the problems of urban object occlusion, canopy occlusion, eaves occlusion, glass light transmission, etc., resulting in defects such as local texture distortion of the 3D model, object pulling, and object cavity voids. There are many problems in model accuracy, quality and application. In order to solve the above problems, this article took the University of Chinese Academy of Sciences as the research area, and used the UAV tilt photography technology and ground lidar technology to perform fusion modeling. In the course of the experiment, a drone image acquisition strategy of "regular route automatic shooting-based, manual interest area supplemented by manual shooting" was used in the field; in interior work, "manual coarse registration, ICP algorithm fine registration" was used. The experimental results show that the method of multi-source data fusion can not only ensure the efficiency of 3D modeling, but also correct the problems of ground distortion and holes in the UAV alone modeling model, improve the accuracy of the model, and optimize the 3D model of the city.
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Research on combined operation mode of the solar hot water storage tank

Wang Ye, Sun zhendong, He Teng, Shi Chengzhi, Zhao Haochen, Li Zhe

Abstract: (582) HTML (0) PDF (0.00 ByteKB) (0)

The fluid flow and heat transfer processes inside three thermal storage tanks with different top or obstacle structures are numerically analyzed in this paper to take advantage of solar energy and improve the comprehensive efficiency of solar energy system with the engineering background of Urumqi region"s solar water heating system for floor heating. The alternate operation mode of each water tank is also discussed. The results show that it is feasible to use the multi-tank alternating operation mode at different times. In actual engineering, on the premise of meeting the needs of hot users, the low-flow operation mode should be preferentially adopted. According to the thermal stratification characteristics of the water tank, 3# water tank is preferentially operated at 11:30, followed by 2# and 1# water tanks. 3# water tank should be preferentially operated at 15:00 and 18:00 while 1# and 2# water tanks can be used as backup for each other. The 3# water tank is more suitable for users with higher water temperature requirements but less water consumption, followed by the 1# water tank. When users generate a lot of backwater and need hot water with higher temperature, the 2# water tank is preferentially enabled.
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A research on feedback cognition method of insulator state based on attention mechanism

Suxinyan, Lijing, Yangjianping, Zhanghaitai

Abstract: (664) HTML (0) PDF (0.00 ByteKB) (0)

In view of the drawbacks of the existing insulator state recognition models, and open-loop cognitive mode and insufficient generalization ability of loss function for detailed recognition deep network, imitated imitating human inspection mode, i.e., real-time evaluation of reliability of cognitive results and self-optimizing and regulation of the multi-scale image knowledge space, this paper explores a feedback cognition method of insulator state based on attention mechanism. Firstly, for the pre-processed insulator image, a stacked convolutional neural network with adaptive scale architecture is designconstructed, which renders the network input is scaled from the overall image to the detailed area. Each scale network shares the same architecture with different parameters to ensure the discriminative ability of different resolution inputs and generate a detailed attention area for the next scale. Secondly, for multiple scale features, stochastic configuration network (SCN) establish builds the classification criterion of the insulator states with universal approximation ability. Thirdly, an inter-class classification loss function and an intra-class ranking loss function are constructed to optimize the attention network, which generates a higher confidence score ranking than the previous prediction. Finally, learned from closed-loop control idea, the generalized error entropy performance index is definestablished to evaluate the reliability of the uncertain cognition results of insulator states in real time. Then, the network scale level is dynamically regulated to realize the self-optimizing regulation of the feature space and the reconstruction of the classification criteria based on the constraint of the uncertain detection results, which renders insulator states is re-recognized with feedback mechanism. Experimental results show that, compared with other network architectures, the proposed method enhances the generalization ability and improves the cognition accuracy of the model.
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BP NEURAL NETWORK MODEL FOR DYNAMIC SWING ANGLE OF SUSPENDED INSULATOR STRING

Sui Jia li, Yan Bo, Lin Xiang, Wu Chuan, Lv Zhong Bin, Zhang Bo

Abstract: (829) HTML (0) PDF (0.00 ByteKB) (0)

The dynamic swing angles of suspended insulator strings of transmission lines with different parameters including conductor type, initial stress in conductor, span length and height difference, under stochastic wind filed are numerically simulated by means of the finite element method. Based on the finite element simulation results and the BP neural network, a prediction model for the swing angle is constructed. In the model, the conductor type, span length, height difference, initial stress, wind speed and guarantee factor are taken as the input parameters, and the swing angle as the output parameter. The model is optimized by machine learning and accuracy evaluation with specific evaluation indicators. Swing angle of suspended insulator string in stochastic wind field can be predicted conveniently and fast with this model, which provides a basis for the insulation design of tower head in transmission line.
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Dynamic Analysis of Oil Droplet Impacting Normally onto a Deep Pool

WANG Bo-dong, CHEN Bo, Ning Hui-ming, GU Zhong-tao

Abstract: (610) HTML (0) PDF (0.00 ByteKB) (0)

To explore the impact characteristics of oil droplets impacting onto the oil film inside aero-engine bearing chamber, a three-dimensional numerical model was proposed using VOF (volume of fluid) method to predict the air/oil two-phase flow during the normal impact between oil droplet and deep pool. The dynamic morphologies of splashing film and cavity, and the initial characteristics of secondary oil droplets were analyzed. Subsequently the effects of droplet diameter and impact velocity were discussed in detail. The results show that the splashing film produced by the impact eventually evolves into a crown film, during which a large number of secondary droplets with different diameter are formed. An approximate hemispherical cavity is formed by the discharged oil in the pool, and the diameters of the secondary droplets satisfy a log-normal probability density function. The crown height and the cavity depth and diameter increase with the increasing droplet diameter and impact velocity. The diameter interval of secondary droplet can become more dispersed with the increasing droplet diameter and the decreasing impact velocity. Finally, the correctness and reliability of the model presented was validated by compared with relevant experimental data.
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Tracking Accuracy Analysis of a Flexible Manipulator with Interval Joint Clearance

Liu Zhiyuan, Sun Dongyang

Abstract: (828) HTML (0) PDF (0.00 ByteKB) (0)

To investigate the influences of large deformation, clearance and uncertainty on the dynamic behavior and control accuracy of a manipulator, a methodology for establishing dynamics model of flexible manipulator with interval joint clearance is presented. Then an evaluation method for the dynamics model is proposed. In this work, the absolute nodal coordinate formulation is used to model the flexible components, while hybrid contact force model and Ambrósio friction force model are applied to construct revolute clearance joint. Meanwhile, intervals are used to characterize clearance size and Young’s modulus. The simulation results show that the flexibility and clearance can obviously affect the dynamic behavior and control accuracy of the manipulator. And the influence will be more significant as Young’s modulus decreases or clearance size increases. Uncertainty can reduce control accuracy and significantly affect the dynamic behavior of the manipulator.
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Research on Storage Mechanism of Electricity Marketing Data Based on Blockchain

WANG Lingyu, FU Hong, YANG Yun, LIU Jun

Abstract: (700) HTML (0) PDF (0.00 ByteKB) (0)

With the development of electricity, electricity marketing data continues to grow, and traditional centralized data storage models have been unable to meet the security and efficiency requirements of power business data storage. Regarding the issue above, this paper proposed a multi-level encrypted electricity marketing data storage architecture based on blockchain. The storage architecture uses the blockchain as the underlying technical support combined with distributed storage to provide highly stable, secure and reliable power data storage performance. At the same time, a multi-level encryption mechanism is proposed on the basis of the blockchain. This mechanism supports step-by-step encryption and verification of power data on-chain and power data transmission processes, which further guarantees the security of power data storage. The paper compares the storage mechanism proposed in this article with the centralized storage mechanism by creating a distributed storage facility. The analysis of the experimental results shows that the storage mechanism proposed in this research has lower latency, lower response time and The advantage of higher throughput shows that the storage mechanism is reasonable and feasible and has good application prospects.
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Optimization design of composite bulkhead structure basedon Response Surface Method

ZENG Yang, ZHOU Jun, SHEN Zhiyuan, YU Zixian, CHEN Hao, YU Rong

Abstract: (688) HTML (0) PDF (0.00 ByteKB) (0)

An optimal design method combining Response Surface Model with Genetic Algorithm was proposed in the present research to ensure reliable structural parameters of bulkhead. The Box-Behnken design method was selected to determine the location of sampling points for generating the response surface, then the total mass property and maximum displacement was established in terms of the input parameters. Then the Pareto optimal solutions are obtained by using Multi-Objective Genetic Algorithm to optimize the Response Surface Model. The numerical simulation results show that the optimized total mass of the composite bulkhead is reduced by 23% compared with that of the steel bulkhead, while the maximum displacement is basically consistent with the steel bulkhead structure. Therefore, the present research provides useful insight to the structural optimization of composite bulkhead structure in engineering application.
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Vibration of elastic restrained simply supported carbon nanotubes

liming, huguiping

Abstract: (656) HTML (0) PDF (0.00 ByteKB) (0)

This paper investigated the free vibration of simply supported single-walled carbon nanotubes (SWCNTs) with both ends restrained elastically. The material property of CNT was simulated by Kelvin-Voigt viscoelastic constitutive relation. Based upon nonlocal Euler-Bernoulli beam theory, the governing partial differential equations of motion and associated boundary conditions were derived by Hamilton's principle. Employed the differential transformation method (DTM) to solve the equation of motion, the influences of the nonlocal parameter, the viscoelastic CNT parameter and restraining elastic coefficient on the dynamic behaviors of the SWCNT were analyzed. It can be concluded that the nonlocal small-scale parameter and the viscoelastic CNT parameter make the SWCNT natural frequency decrease. More importantly, the results show that it will be a convenient and effective way to increase the natural frequency SWCNT system through additional elastic restraining with proper coefficient on two ends while their values are low．
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Dynamic Analysis of a Functionally Graded Material Beam Undergoing Large Overall Motions

gaoxiang, duchaofan, zhangdingguo, zhouxiaoting

Abstract: (648) HTML (0) PDF (0.00 ByteKB) (0)

The dynamic characteristics of a hub-functionally graded material beam undergoing large overall motions are studied. The deformation field of the flexible beam is described by using the assumed mode method and the finite element method. Assuming that the physical parameters of functionally graded materials follow certain kind of power law gradient distribution and vary along the thickness direction. The longitudinal deformation and transversal deformation of the beam are both considered, and the nonlinear coupling term which is known as the longitudinal shortening caused by transversal deformation is also taken into account. The rigid-flexible coupling dynamics equations of the system described by two different discrete methods which have a uniform form are derived via employing Lagrange’s equations of the second kind. The validity of the finite element method established in this paper is verified by comparison with the numerical simulation results of the assumed mode method. The limitation of the assumed mode method based on small deformation assumption is illustrated by the example of large deformation. On this basis, the influence of functional gradient distribution rules on the dynamic characteristics of flexible beams undergoing large overall motions is discussed. The results show that the assumed mode method cannot deal with large deformation problem. Remaining other physical parameters of functionally graded materials beam unchanged, the maximum displacement of the beam increases with the increase of functionally graded materials index. The natural frequency of transverse bending of beam increases with the increase of rotational speed, when rotational speed is constant, the natural frequency will decrease with the increase of functional gradient index.
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Compressed singular value decomposition equivalent source method for sound source identification of structural panels

heyansong, chenliangsong, xuzhongming, zhangzhifei

Abstract: (818) HTML (0) PDF (0.00 ByteKB) (0)

Equivalent Source Method (ESM) based on compressed sensing (CS) theory is being applied to Nearfield acoustic holography (NAH) gradually to reduce the spatial sampling points and broaden the frequency range of sound source identification. For the spatially extended sound source, a compressed singular value decomposition equivalent source method (CSVDESM) is proposed to improve the performance of sound field reconstruction and the sound source identification. The sound field to be reconstructed is first modeled using ESM. Then a series of orthogonal basis of the source field are obtained by the singular value decomposition, and the reconstruction is accomplished in the CS framework. Finally, combined with the high-order matrix function beamforming, the output of CSVDESM is modified and the identified acoustic center coverage is continuously narrowed by increasing order value, and hence the accuracy of sound source identification can be improved. Numerical simulation and experiment verify the validity and practicality of CSVDESM.
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Seismic analysis and optimization of lifting-turnover mechanismof strong-radiation rods

ZHOU Jie, SHI Hui-min, Wang Shi-long, Yang Bo, Li Hai

Abstract: (640) HTML (0) PDF (0.00 ByteKB) (0)

The lifting-turnover mechanism is the key equipment of a strong-radiation rod post-processing system. According to the relevant design specifications, it is necessary to ensure that the rods does not break under seismic conditions and that the safety function and running performance of the mechanism are normal. To verify the seismic performance of the mechanism, based on ANASYS Workbench, finite element models of the lifting-turnover mechanism contained a hoist, a steel-wire rope, a silo rack-silo part, a rolling-over vehicle and upper/lower rails in the post-processing system, are established for seismic evaluation. Then, the stress assessment and strength check of the main units and the major bolts are carried out according to ASME codes, and the number of bolts installed on the upper rail is optimized. Finally, the simulation results show that the optimized lifting-turnover mechanism meets seismic design requirements of the under nuclear working condition.
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Volume 48,2025 Issue 10

Special Column for Power Grid Safety and Operation

Communication·Computer·Automation Engineering

Volume 48,2025 Issue 10

电气·热能·材料工程

电气·热能·材料工程

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