Volume 46,Issue 8,2023 Table of Contents

1 Surface electric field characteristics of bundle wire and expanded wire in icing area

MA Jun , LIAO Longfei , YU Jianbo , LIU Zhenhua , JIANG Xingliang , HU Qin

2023, 46(8):1-10. DOI: 10.11835/j.issn.1000-582X.2021.221

[Abstract](355) [HTML](128) [PDF 1.68 M](857)

Abstract:
The icing disaster of transmission line poses a serious threat to the safe operation of power systems. Currently, a variety of anti-icing and de-icing methods have been developed, but each method has its limitations. Particularly, serious icing areas with micro-climate and micro-topography characteristics lack effective solutions. This paper takes into account the characteristics of expanded conductors and the limitations of bundle conductor transmission lines. By considering wave impedance, natural power, and accounting for the skin effect of current, the split conductor is equivalently transformed into a single conductor, and the equivalent single expanded conductor is obtained. Subsequently, the surface electric field characteristics of the split conductor and its equivalent single expanded conductor in icing area are analyzed and compared. The findings reveal that when the total conductor cross-sectional area of the conductor cross-section before and after the equivalent remains the same and the wave impedance is equal, the expanded conductor, compared to the bundle conductor, not only significantly reduces the number of sub-conductors and the icing load on the transmission line, but also the maximum electric field intensity on the surface of the expanded conductor is lower than that of the bundle conductor when the radius of the expanded wire is equal to the equivalent single wire radius of the bundle conductors. Therefore, in severely icing areas, the expanded wire with an equivalent radius to that of the bundle conductors exhibits excellent surface electric field characteristics, significantly reducing ice wind load and improving anti-icing capacity.

2 Artificial intelligence-based early warning and self-healing technology for distribution edge IoT networks

LI Weiqing , CHEN Hongyu , ZHAO Ruifeng , HU Chunqiang

2023, 46(8):11-19. DOI: 10.11835/j.issn.1000-582X.2021.224

[Abstract](369) [HTML](69) [PDF 2.19 M](523)

Abstract:
The distribution of IoT (Internet of Things) is the last link in the construction of ubiquitous power IoT. It possesses characteristics such as short power supply path and high load density, which bring about significant challenges in terms of protection and control. To address these challenges, the establishment of an early warning and self-healing strategy for the distribution network is crucial, enabling the formation of a smart distribution network with flexible operation mode, timely fault warning and perfect fault self-healing. This paper proposes a security defense technology framework applicable to the firmware of the distribution IoT edge network. The framework protects the reliability matrix of each firmware present in the edge devices, while the edge devices are interconnected through the edge servers, forming a technical solution for distribution edge IoT that incorporates security warning and self-healing capabilities. Finally, the feasibility of this scheme is verified by simulation experiments conducted under different environmental conditions.

3 Annual power generation plan optimization model considering deep peak regulation auxiliary services and multiple typical days

ZHANG Aifeng , LIU Huorang , WANG Yong , AI Lin , ZHOU Ying , JIANG Zhenyong , SANG Fumin , LIN Zugui , YAN Wei

2023, 46(8):20-31. DOI: 10.11835/j.issn.1000-582X.2021.222

[Abstract](236) [HTML](40) [PDF 1.67 M](681)

Abstract:
In the context of the deep peak regulation auxiliary service market, the costs of unit peak regulation and auxiliary service fees have a significant impact on power generation companies. To address this issue, this paper proposes an optimization model for annual generation plan that takes into account deep peak regulation auxiliary services and multiple typical days. To achieve effective scene acquisition, a typical scene clustering method with considering the coupling of load and wind power is proposed, thereby effectively solving the simulation problem of multiple typical daily scenes in a month. By considering the deep peak regulation cost, auxiliary services compensation, benefit from electricity sales and carbon trading cost, the model established the income constraints of generation companies participating in the auxiliary service market to ensure profitability for market entities. As the model is a nonlinear mixed integer programming problem, this paper uses linearization strategy and CPLEX solver to achieve an efficient solution. Finally, simulation analysis is conducted using a modified example system, verifying the effectiveness of the proposed model.

4 Propagation and reflection of stress wave about primary and secondary waves in rectangular plates

LI Xi , LIU Zhanfang

2023, 46(8):32-44. DOI: 10.11835/j.issn.1000-582X.2022.266

[Abstract](276) [HTML](57) [PDF 2.29 M](550)

Abstract:
The modified theory of elastic stress waves asserts that the wave equations governing volume strain are consistent with existing theories, but a new set of weakly coupled wave equations encompassing both volume strain and partial strain has been developed. To address the problem of stress wave fluctuation caused by a concentrated load impact on a rectangular plate, two sets of control equations for stress wave propagation as well as the fluctuation boundary conditions of loading surface and free surface are established in this paper. 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. During propagation, the partial strain splits into two parts: one part propagates together with the volume strain, forming the main wave, while the other part propagates at a slower pace, resulting in the formation of a secondary wave. The numerical simulation results show complete consistency with regard to the propagation image of the stress waves in the nanocalcium glass plate under shock loading.

5 Energy evolution of hexagonal honeycomb under different graded cyclic loading and unloading modes

ZOU Quanle , ZHOU Xiaoli , WANG Ruizhi , LIU Hao , LIU Ying

2023, 46(8):45-55. DOI: 10.11835/j.issn.1000.582X.2022.268

[Abstract](353) [HTML](86) [PDF 3.86 M](620)

Abstract:
In order to examine the effects of cyclic loading and unloading paths on the energy evolution of hexagonal honeycomb, three different graded cyclic loading and unloading tests were conducted. These tests aimed to reveal 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. The findings show that the initial peak strength and platform stress of the honeycomb are influenced by the release of the elastic energy during the unloading process. The total external input energy, elastic deformation energy and plastic deformation energy of the honeycomb exhibit a nonlinear increase as the number of unloading levels rises. 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, resulting in an inverse trend in the dissipation energy. As the upper limit of the cyclic load is elevated, the damage inside the honeycomb increases, with the severity increasing closer to the initial peak strength of the honeycomb. Furthermore, raising the lower limit of the cyclic load leads to a reduced release of elastic energy and amplifies the level of damage.

6 End slope mining technology of top coal seam in Baorixile open-pit mine

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

2023, 46(8):56-67. DOI: 10.11835/j.issn.1000-582X.2023.251

[Abstract](212) [HTML](65) [PDF 4.86 M](643)

Abstract:
At present, there are limitations in the mining and construction process of the end slope of near-horizontal composite coal seam open-pit mines. Existing studies mainly focus on mining the lower coal seam, while mining the top coal seam is more difficult and has received less attention. Therefore, to address the mining of the top coal seam in the near-horizontal composite coal seams, this study analyzes the engineering geological conditions and strata occurrence characteristics of the Baorixile open-pit mine slope. A three-dimensional numerical simulation model of the end slope is constructed using FLAC^3D, and the relationship between the filling step distance and the slope stability is calculated when mining the top coal seam 1-2 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 findings show that the replacement step distance of the top-level coal seam in the end-slope 1-2 coal seam should not exceed 80 m. When mining the top-level coal seam in the end-slope 1-2 coal seam, the equipment is arranged on the flat plate of the inner dump extended to the bottom plate of the 1-2 coal seam. The mining method involves layered tamping and inner row tracking backfilling. By employing end slope mining, the whole region can recover 2.260×10⁷ t coal from the 1-2 seam, resulting in an income of 4.972 billion yuan.

7 Study on the law of tailings deposition under different discharge concentration

ZHANG Diao , WANG Guangjin , SHEN Yingming , DONG Zhicheng , LI Xiaoshuang , LI Yaoji , SUI Sugang

2023, 46(8):68-77. DOI: 10.11835/j.issn.1000-582X.2023.08.007

[Abstract](290) [HTML](46) [PDF 3.76 M](579)

Abstract:
The deposition law of tailings after discharge affects the stability of tailings dam. In order to study the characteristics of tailings deposition under different slurry discharge concentrations, this paper takes a tailings pond in Yunnan as the research object, and studies the tailings deposition law under different slurry discharge concentrations through field tests and indoor scale dam model tests. The critical state of single tailings particles is analyzed, and the relationship between the movement-deposition critical velocity of tailings particles and the migration distance formula of particles with different particle sizes on dry beaches are derived. The results show that there are more coarse tailings in the front of the dam of the sedimentary beach, and the farther away from the sub-dam, the more fine-grained tailings are deposited. The tailings flow velocity on the dry beach surface is negatively correlated with the slurry concentration and positively correlated with the tailings mortar pressure. The greater the concentration of the viscous high concentration tailings mortar, the weaker the flow force, and the greater the slope formed by the deposition; with the increase of slurry concentration, the deposition length of slurry also increases. The deposition distance of tailings particles on the dry beach surface is proportional to the initial velocity of slurry discharge, and inversely proportional to the dry beach slope, slurry discharge concentration and particle size. The research results can provide some reference for the stability analysis of tailings dam.

8 Effect of double-row anti-slide piles on thrust distribution

WANG Yuan , XIE Qiang , ZHANG Jianhua

2023, 46(8):78-87. DOI: 10.11835/j.issn.1000-582X.2023.08.008

[Abstract](215) [HTML](62) [PDF 2.45 M](590)

Abstract:
At present, there is no clear design specification for the design of double-row anti-slide piles. In the design process, the thrust distribution between the front-row and back-row anti-slide piles is solely based on experiential judgement. To investigate the thrust share ratios basis between front-row and back-row piles, this paper establishes a series of finite element models to analyze the safety factor of slopes and the magnitude of landslide thrusts under various pile conditions. The findings show that the layout of piles has a significant impact on the slope’s safety. There exists an optimal pile spacing that maximizes the safety factor against landslides. Moreover, the proportion of thrust distribution between the front-row and back-row piles varies with different pile conditions. When the row spacing is set to 30 m, the thrust of the two rows of piles is the most balanced.

9 Soil-water characteristics and stability of city walls under rainfall conditions

WU Kai , SHEN Feng , LI Bingyi , ZHANG Qing , CHEN Weirong

2023, 46(8):88-100. DOI: 10.11835/j.issn.1000-582X.2023.08.009

[Abstract](282) [HTML](47) [PDF 2.89 M](621)

Abstract:
Rainfall infiltration can affect the stability of the city wall, eventually leading to instability and collapse. This study focuses on the city wall as the object of study and investigate the physical and mechanical properties as well as unsaturated properties of the soil through experiments. Based on the experimental data, a shear strength formula with variable water content is derived, and the safety factor expression is obtained using the Bishop method. Finite element analysis and stability evaluation are conducted on the seepage field of the city wall slope under different working conditions, and the stability change of the city wall and the distribution of pore water pressure during the plum rain season are analyzed. The results show that with the continuous progress of rainfall, the pore water pressure gradually increases, the surface soil begins to saturate, the depth of infiltration continues to increase in the early stage, while the groundwater level rises in the later stage. The stability of the city wall continues to deteriorate during the rainy season, greatly affected by the total amount and duration of rainfall. These findings serve as a theoretical reference for the design and construction of the city wall repair and other projects in the region under typical regional climatic conditions.

10 Visual evaluation system for night lighting of tower-style ancient pagoda buildings

HOU Wanjun , JIA Tie , WANG Lixiong , YANG Ruonan , XING Wenlu

2023, 46(8):101-111. DOI: 10.11835/j.issn.1000-582X.2021.061

[Abstract](248) [HTML](60) [PDF 2.12 M](535)

Abstract:
With the rapid development of urban nightlife, there is an increasing demand for the lighting effects of landmark buildings in the core areas. One such landmark is the ancient tower, which represents a typical oriental architectural style. However, the current satisfaction level with the night lighting effect of the ancient tower is low, and there is a lack of relevant studies in this area. This study begins with extensive investigations, measurements and research visits in the early stage to identify and analyze the factors that influence human visual perception of the aesthetic appeal of night lighting in ancient towers. Then, structural equation modeling and the AMOS software are used to analyze the relationships between variables and evaluate the factors influencing the visual perception of night lighting effect in ancient tower buildings. A quantitative analysis is constructed to understand the relationship between these influencing factors. Through model fitting, adjustment and analysis verification, the underlying relationship between core elements are further interpreted. Finally, the core evaluation elements are elaborated and analyzed from a quantitative perspective. The outcome is an objective and reasonable visual evaluation system for the night lighting of ancient tower buildings, which provides data and reference standards for the design, planning and construction of night lighting projects in ancient tower buildings.

11 Research on aging characteristics of recycled asphalt and its induced aging of new asphalt from hot in-plant recycled asphalt mixture

LI Qiang

2023, 46(8):112-119. DOI: 10.11835/j.issn.1000-582X.2023.08.011

[Abstract](279) [HTML](58) [PDF 1.24 M](580)

Abstract:
In order to explore the aging process and mechanism of new asphalt in plant hot-mixed recycled asphalt mixture, the dynamic viscosity and partial road performance of the recycled asphalt, the mixture of new and old asphalt and the matrix asphalt after RTFOT aging and PAV aging were tested. The macroscopic performance attenuation law of the mixture of new and old asphalt during the aging process in thermal regeneration was compared and analyzed. After that, the aging process and mechanism of the mixture of new and old asphalt were explored by infrared spectroscopy and differential calorimetric analysis scanning. The results show that RTFOT aging and PAV aging make the viscosity of recycled asphalt rise significantly and the low temperature performance decline rapidly. After RTFOT aging and PAV aging, the change range of dynamic viscosity and low-temperature performance of the mixture of new and old asphalt is much higher than that of the matrix asphalt, which proves that the aging rate is faster than that of matrix asphalt. Meanwhile, microscopic analysis show that in addition to the independent aging of new asphalt and recycled asphalt, there is also a chemical effect between them, that is, some active groups in recycled asphalt have a more obvious promotion effect on the aging process of new asphalt, here called induced “aging”. This induced aging changes the aging mechanism of the matrix asphalt by changing the aging process of it.

12 Whale optimization algorithm based on iterative mapping and nonlinear fitting

LI Saiyu , JU Chuanxiang , DING Hangqi

2023, 46(8):120-131. DOI: 10.11835/j.issn.1000-582X.08.012

[Abstract](210) [HTML](45) [PDF 1.91 M](566)

Abstract:
In order to solve the problems of slow convergence speed and low optimization accuracy in whale optimization algorithm, a whale optimization algorithm based on iterative mapping and nonlinear fitting(NWOA) is proposed. Firstly, iterative mapping is taken advantage to initialize whale population, which guarantees initial population diversity. Secondly, nonlinear fitting strategy is used to improve the convergence factor and inertia weight to balance the global survey ability and local development ability of the algorithm. Through the simulation test of 13 functions, the improved algorithm has a significant improvement in precision and stability from the point of mean square error and average value. The experimental results show that the convergence speed of the algorithm is faster than that of the traditional whale optimization algorithm.

13 Multivariable traffic flow prediction model based on convolutional neural network and gate recurrent unit

WANG Bowen , WANG Jingsheng , WANG Tongyi , XIA Tianyu , ZHao Danting

2023, 46(8):132-140. DOI: 10.11835/j.issn.1000-582X.08.013

[Abstract](425) [HTML](109) [PDF 2.60 M](889)

Abstract:
For multi-step forecasting of traffic flow, a convolutional neural networks (CNN)-gate recurrent unit (GRU) model based on encoder-decoder (ED) framework was proposed, referred to as the ED CNN-GRU model. In this model, CNN serves as the encoder, capturing information from the traffic flow sequence, which is then interpreted and outputted by the GRU decoder. Experimental results show that compared with CNN and GRU models, ED framework effectively solves the problem of rapid error accumulation. Compared with other benchmark models, CNN and GRU models are superior in feature extraction and interpretation of traffic flow series. In terms of the traffic flow prediction task of 12 steps in the future, compared with other benchmark models, the root mean square error of the univariate input ED CNN-GRU model is reduced by about 0.344 to 6.464, and the mean absolute error is reduced by about 0.192 to 0.425. Additionally, compared with univariate input, the ED CNN-GRU model with multivariate input exhibits a better fitting performance. These findings confirm that ED CNN-GRU model possesses strong forecasting capabilities for multi-step traffic flow forecasting tasks with varying input dimensions, and provides a multi-step traffic flow forecasting model that supports both univariate and multivariate input for cities with diverse data acquisition conditions.

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