Volume 44,Issue 7,2021 Table of Contents

1 Analytical modeling and pole-slot combination of magnetic field in surface-mounted permanent-magnet synchronous motor

DU Gang , DENG Zhaoxiang , ZHANG Heshan , YANG Minglei , TANG Xiaoli

2021, 44(7):1-13. DOI: 10.11835/j.issn.1000-582X.2020.235

[Abstract](841) [HTML](1749) [PDF 7.42 M](1315)

Abstract:
Reasonable selection of pole-slot combination is a key part of electric machinery design. In order to solve the problems of time-consuming and resource-consuming caused by repeated modeling with traditional finite element technology, an analytical model of permanent magnet synchronous motor is established to analyze the influence of different pole-slot combinations on motor performance. In 2D polar coordinate system, the motor is divided into four regions: armature slot, stator slot opening, air gap and permanent magnet. Then, the Laplace equation or Poisson equation of each sub-domain is constructed. The sub-domains are analytically calculated by combining the variable separation method with the boundary conditions, and the construction of the motor’s analytical model is completed accordingly. The correctness of the analytical model is verified by the finite element method. Using the analytical model, the effects of different pole-slot combinations on the performance of the motor are studied. The results show that the 60-slot-8-pole motor has better performance of output torque with much smaller cogging torque than the others. The load radial air gap flux density of fractional pole-slot combination is more sinusoidal than that of integer pole-slot combination, which can effectively reduce torque ripple. Within a certain range, multi-slot structure is beneficial to promoting the performance of motor’s output torque.

2 Correlation analysis of driving dynamic parameters and RDE characteristics

YANG Changzhi , DU Baocheng , LI Yuebing , XIANG Gan , RAN Linyao , ZHANG Li

2021, 44(7):14-25. DOI: 10.11835/j.issn.1000-582X.2020.220

[Abstract](482) [HTML](1068) [PDF 15.41 M](681)

Abstract:
To explore the influence of v·a_pos[95] and relative positive acceleration(RPA) on emission characteristics of gasoline duty vehicles in the real driving emission (RDE) test, RDE emission tests are carried out on three China VI light gasoline vehicles using the OBS-ONE Portable Emission Measure System (PEMS) under smooth, normal and rough driving behaviors. Window travel dynamic parameters and section travel dynamic parameters are calculated and the correlation between the dynamic parameters and pollutant emission characteristics is analyzed. The results show that the fluctuation range of the window travel dynamic parameters v·a_pos[95] and RPA correlation coefficients with CO and PN emission factors of the three vehicles is significantly reduced compared with the travel dynamic parameters prescribed by the regulations. The fluctuation range is 25%-44%, 38%-64% and 73%-96% in urban, rural and motorway respectively. Moreover, the NO_xemission factor is only strongly correlated with the RPA of the window. Therefore, it can be concluded that the correlation between the window travel dynamic parameters v·a_pos[95] and RPA and pollutant emission factors is more obvious, which can better reflect the emission levels of pollutants under different driving behaviors.

3 Car-following model with improved molecular dynamics

YANG Longhai , WANG Hui , LI Shuai , QIU Xiaoyun

2021, 44(7):26-33. DOI: 10.11835/j.issn.1000-582X.2020.228

[Abstract](475) [HTML](691) [PDF 4.51 M](686)

Abstract:
In order to better study the car-following characteristics of vehicles in complex situations, the car-following behavior of vehicles is analogous to the result of the interaction of molecules in a one-dimensional pipeline. The existing car-following model based on molecular dynamics uses the demand safety interval and the expected vehicle speed as the main factors to establish the molecular car-following model, ignoring the influence of the relative speed on the driver’s car-following behavior, which does not conform to the real car-following situations. Therefore, by incorporating the relative velocity of the vehicle into the model structure, this paper establishes the molecular interaction potential function and the wall potential function, and constructs a car-following model with improved molecular dynamics accordingly. The parameters in the car-following process are collected by high-precision vehicle-mounted instruments and the model parameters are calibrated by genetic algorithm. Finally, the accuracy of the model under different car-following states is verified and compared with the previous molecular model. The results show that the improved molecular car-following model can more effectively predict the car-following behavior of the vehicles.

4 A multi-modal feature fusion radar knowledge recommendation method based on attention mode

LI Wen'an , CHEN Liuliu , CHEN Shi

2021, 44(7):34-42. DOI: 10.11835/j.issn.1000-582X.2020.307

[Abstract](502) [HTML](623) [PDF 1.54 M](748)

Abstract:
In order to quickly and accurately find the radar knowledge and information that researchers are interested in and make recommendations from a large number of radar knowledge data, this paper proposes a multi-modal feature fusion radar knowledge recommendation method based on attention model, which can learn high-level fusion feature representation from multiple modalities for the radar knowledge. Then the radar knowledge recommendation can be performed using the learned fusion feature. The proposed method consists of four stages, i.e., data preprocessing, multi-modal feature extraction, multi-modal feature fusion, and radar knowledge recommendation. Extensive experiments demonstrate that, compared to the existing methods using only single-modal features and simple concatenation of multi-modal features, the multi-modal fusion features learned by the proposed method achieves significant improvement in precision, recall, and F₁ value for radar knowledge recommendation, suggesting its effectiveness for radar knowledge recommendation.

5 Comparative analysis of simulation of multi-car-following models under SUMO platform

CUI Jufu , HU Benxu , XIA Hui , CHEN Fei , CHENG Xiangguo

2021, 44(7):43-54,98. DOI: 10.11835/j.issn.1000-582X.2020.250

[Abstract](1121) [HTML](1118) [PDF 5.86 M](1264)

Abstract:
Vehicle Ad Hoc Network (VANET) is a kind of wireless ad hoc network, which takes the vehicle as the communication node. It aims to achieve data transmission between vehicle and vehicle, or between vehicle and infrastructure. The high-speed mobility of vehicles can easily cause the change of network topology, reducing the transmission rate of data packets and the efficiency of routing protocol and even leading to channel interruption. The research on the communication protocol and application of the VANET is mainly implemented by the simulation platform. The performance of vehicle mobility model embedded in the platform for protocol analysis and research is crucial. In this paper, firstly, various car-following models under the Simulation of Urban Mobility (SUMO) platform are described in details. Then, three factors that have the most obvious impact on the performance of mobile models are introduced. Finally, based on the urban road traffic environment, the three indicators of vehicle density, average vehicle speed and road occupancy rate under different car-following models are compared and analyzed in different simulation scenarios. The results show that Krauss model has best performance. In addition, simulating the car-following behavior of a single vehicle reveals the working mechanism of each model microscopically.

6 Hyper-chaotic color image encryption algorithm based on Hash and DNA coding

YUAN Li , XIE Li , LONG Ying , HU Chunqiang , JIANG Taojin

2021, 44(7):55-63. DOI: 10.11835/j.issn.1000-582X.2021.07.006

[Abstract](494) [HTML](751) [PDF 12.90 M](706)

Abstract:
The security of color image has always been concerned by scholars. To deal with the defects of traditional color image encryption algorithm, such as poor scrambling effect,weak diffusion characteristics and resistance to statistical attacks,this paper presents a Hyper-chaotic Color Image Encryption Algorithm based on Hash and DNA coding. In the proposed algorithm,the parameters of Arnold chaotic map are generated by hash algorithm first; then, combined with Arnold chaotic map and Logistic chaotic map, the image is scrambled in three dimensions of R, G, and B; Finally, the image is chaotically processed using DNA coding. The theoretical analysis and computer simulation show that the proposed algorithm has good encryption effect, and it has good resistance to statistical and differential attacks.

7 Research and development of threat and risk evaluation model for smart substation

LIU Yuansheng , WANG Sheng , BAI Yunpeng , XIA Xiaofeng

2021, 44(7):64-74. DOI: 10.11835/j.issn.1000-582X.2021.07.007

[Abstract](378) [HTML](713) [PDF 710.14 K](885)

Abstract:
Due to the lack of efficiency and stability in the deployment of traditional intrusion detection systems in resource-limited industrial equipment, an intrusion detection system for intelligent substations was proposed to supplement the evaluation model of industrial equipment security risks. The system used a gray model-based network vulnerability node active prediction method to balance the weight of threat sources in the established threats and risk assessment model. A risk value calculation algorithm based on the three-dimensionality of information security is proposed. The algorithm used a fuzzy consistent judgment matrix to calculate the risk value parameters. Therefore, a risk evaluation that can intuitively determine the scope and extent of the attack on the system was completed. Through relevant experiments, the system can effectively detect intrusion attacks and have good performance while satisfying the passive, low load, real-time and reliability in the deployment environment.

8 Short-term wind power forecasting based on integrated multi-scale LSTM

YI Shanyun , WANG Hanjun , XIANG Yong , TIAN Changyi , GAO Dayu , CHEN Zhikui

2021, 44(7):75-81. DOI: 10.11835/j.issn.1000-582X.2021.07.008

[Abstract](590) [HTML](883) [PDF 2.56 M](742)

Abstract:
Wind energy is a pollution-free renewable energy, and the proportion of wind power is increasing year by year globally. In view of the large fluctuations in the output of wind power generation, which leads to the instability of the grid power, a short-term wind power prediction model based on integrated multi-scale long short-term memory (LSTM) is proposed. By using LSTM’s special processing capabilities for sequence data, combined with the information contained in different scales’ time data, to predict short-term wind power after integration. It is conducive to comprehensive control and dispatch of power resources. Experiments are conducted on the real data set of wind power generation in the northeast of our country, and the results prove that the method in this paper has high prediction accuracy and strong stability.

9 Research on high gain bridge compensation network for low voltage input MC-WPT system

SHANG Jie , JIA Jianbo , DAI Xin , HUANG Junxin

2021, 44(7):82-98. DOI: 10.11835/j.issn.1000-582X.2021.07.009

[Abstract](335) [HTML](1048) [PDF 8.21 M](653)

Abstract:
Due to the loosely coupled characteristics of wireless power transfer (WPT) systems, the gain from input voltage to output voltage of traditional WPT systems are generally low. This is the problem of insufficient gain in the application of low voltage input and high voltage output of photovoltaic. In this paper, a new power conversion topology based on bridge compensation network is proposed. The impedance characteristics and energy transmission characteristics of the system based on bridge compensation network are studied, and an improved bridge compensation network scheme is given. On this basis, the parameter design method of bridge compensation network is proposed. Finally, the validity of the proposed method is verified by experiments, which can achieve 2-9 times gain from input voltage to output voltage.

10 A global motion estimation algorithm based on L1-norm minimization

FENG Xin , ZHANG Jie , ZHANG Jie , JIANG Youni , YANG Wu

2021, 44(7):99-107. DOI: 10.11835/j.issn.1000-582X.2021.07.010

[Abstract](378) [HTML](911) [PDF 3.86 M](740)

Abstract:
In the field of video content analysis and understanding, it is important to make good perception of spatial and motion features of objects in the video. However, in practice, object movement often mixes up with the camera movement which conceals the objects’ true trajectories. The camera movement, also named as globalmotion, which is induced by the movement of camera, is ubiquitous in the current popular we-media videos. To reveal the true object motion from the trajectories obtained from tracking algorithms, we propose a global motion estimation algorithm based on L1-norm minimization, and obtain the real motion trajectory of the foreground object, where the global motion compensation is realized. Experiments show that our algorithm could accurately estimate the inherent various global motions and restore the true motion trajectories effectively.

11 A water quality prediction model based on genetic algorithm and SVM

MA Chuang , WANG Yao , LI Linfeng

2021, 44(7):108-114. DOI: 10.11835/j.issn.1000-582X.2021.07.011

[Abstract](525) [HTML](1063) [PDF 516.64 K](740)

Abstract:
Water quality prediction is one of the important aspects of many water-related issues. Through water quality prediction, we can find signs of water quality deterioration, which facilitates decision-makers to take measures in advance. In this paper, a water quality prediction model based on genetic algorithm and SVM is used to adapt the weight of pollutants in current application to improve the accuracy of prediction on the basis of common water quality data. The model first uses the genetic algorithm to train the feature weight vector of the current data to adapt the weight to the current prediction, and then apply the feature weight vector in the SVM model training. After conducting experiments with a sewage treatment plant in Chongqing, the feasibility of the model in practical application was verified. Our study provides a new idea for water quality prediction.

12 Design and implementation of embedded real-time face detection system based on VPU acceleration

YAN Jia , ZHANG Yuelin , DENG Changjian

2021, 44(7):115-128. DOI: 10.11835/j.issn.1000-582X.2021.07.012

[Abstract](445) [HTML](650) [PDF 6.19 M](802)

Abstract:
The high design cost and huge computing resource demand of intelligent devices have become the main obstacles to the implementation and application of deep learning algorithm in portable and low-power devices. In order to solve these problems, in this paper, based on the raspberry PI platform and with the help of Intel video processing unit(VPU) low-power acceleration module, a real-time face detection system based on CNN model with residual feature extraction module was designed and implemented. The experimental results show that compared with using central processing unit(CPU) of raspberry PI alone, the proposed method achieved 18.62 times and 17.46 times acceleration respectively in the experiments of face detection and face alignment detection in video stream. It realized the fast, real-time and online face detection and face alignment extraction in portable devices. Meanwhile, it also provided a feasible scheme for the operation of deep learning algorithm in portable and low power devices.

13 The experiment and simulate study of buckling restrained L-shape superimposed steel damper

YANG Yiming , YANG Pu , SHU Yuan , LI Yingmin , FENG Liqiang , ZHANG Xiaobin

2021, 44(7):129-138. DOI: 10.11835/j.issn.1000-582X.2021.07.013

[Abstract](284) [HTML](439) [PDF 3.92 M](507)

Abstract:
Applying the seismic energy dissipating damper in the self-centering structure can reduce the damage of the beam and column caused by the earthquake. The structure can be quickly restored by replacing the damaged dampers. We propose a new buckling restrained L-shape superimposed steel damper connecting with high-strength bolts which can dissipate the most seismic energy through the steel plate. The proposed damper can avoid the buckling of the steel plate through the additional restraining devices, and easily be replaced after earthquake. The flange of the beam end can be reinforced by the new damper, which also can be regarded as a shear transfer device. The consequences of the axial tension and compression test and ABAQUS simulation indicate that the proposed buckling restrained L-shape superimposed steel damper has essential capabilities of energy dissipation and good bearing and stiffness with the sufficient connecting strength.

14 Study on the progressive collapse of the base-isolated mountain step-terrace structure

YANG Youfa , YANG Tianhang

2021, 44(7):139-148. DOI: 10.11835/j.issn.1000-582X.2021.07.014

[Abstract](354) [HTML](756) [PDF 1.19 M](717)

Abstract:
In order to study the anti-progressive collapse performance of the base-isolated step-terrace structure, a 4-span 3-story plane frame was simulated to verify the reliability of the LSDYNA computing platform. Then, in compliance with the national specifications, six basic isolation and step-terrace system frames and one ordinary flat isolation structure were designed, and the collapse resistance of the remaining structure was studied based on the demolition method to obtain the load coefficient and the vertical displacement curve of the failure point. The results show that when the lower grounded corner column(support) and the upper grounded corner column were removed, the anti-collapse ability of the flat ground isolation structure was greater than that of the base-isolated step-terrace structure; when the upper ground support was removed, the anti-collapse ability of the flat ground isolation structure was weaker than base-isolated step-terrace structure. Furthermore, the resistance mechanism of the failure span of the bottom support(bottom column) adjacent to the sill lagged behind the resistance mechanism of the upper ground span. Our study provides reference for the anti-progressive collapse design of the base-isolated step-terrace structure.

15 Thermodynamic analysis of calcium carbide manufacturing process by coal-coke-electricity grading substitution

MA Shuo , MA Danan , LI Renxi , MA Hongting

2021, 44(7):149-160. DOI: 10.11835/j.issn.1000-582X.2021.07.015

[Abstract](420) [HTML](1285) [PDF 1.13 M](781)

Abstract:
In order to analyze the utilization and loss of energy and phosphorus in the production of calcium carbide by the new process of coal-coke-electricity grading substitution, and evaluate the different calcium carbide production processes scientifically, this paper analyzes the material balance, energy balance and exergy balance of the new process based on the actual operation data of a domestic calcium carbide production enterprise. The new process of coal-coke-electricity grading substitution, electrothermal method and oxycaloric method were evaluated against the comprehensive energy consumption index and exergy index of multiple products with different target products as benchmarks. The results show that in the total energy and total exergy input into the new system, the energy and exergy proportion of the cold pellet into the pyrolysis furnace are the highest, 69.36% and 71.85% respectively; in the total energy and total energy output of the new system, the energy and exergy proportion carried out by calcium carbide are the highest, which are 71.97% and 69.09% respectively; among the various heat losses, calcium carbide furnace gas takes the most heat, accounting for 15.12% of the total heat output. The power consumption per unit product of the new process is only 2.48 kWh/kg-CaC₂, which is 23.93% lower than that of 3.26 kWh/kg-CaC₂ of electrothermal method. When CaC₂ is the only target product, the new process has the lowest comprehensive energy consumption of 10.22 kWh/kg-CaC₂ per unit product and comprehensive exergy consumption of 9.15 kWh/kg-CaC₂ per unit product. Compared with the traditional electric heating method and oxygen heating method, the new process has obvious advantages of energy saving and exergy saving.

16 Research and application of GIS-based multiple-criteria decision making method for dual objectives

LYU Fei , XIE Qian , DAI Jian

2021, 44(7):161-170. DOI: 10.11835/j.issn.1000-582X.2021.07.016

[Abstract](481) [HTML](1452) [PDF 3.46 M](734)

Abstract:
Currently, the GIS-based multiple-criteria decision making(GIS-MCDM) for single-objective is generally used for spatial suitability evaluation, but the way of selecting objectives is overly subjective, because there is no function to compare objectives before selecting them. Based on the research results about GIS-MCDM method in the past 30 years, this paper proposes a GIS-MCDM approach for dual-objectives that can be effectively combined with ArcGIS software. In comparison with MCDM for single-objective, our method adds a function of objective decision-making, which makes spatial suitability evaluation be able to deal with conflicting objectives. Our study establishes a systematic procedure for decision space approach, which is the core of dual-objective decision making. Moreover, a new way of partitioning conflict region on decision space is introduced. This approach keeps the ratio of the area to conflict region assigned to the objectives equal to the ratio of the weights assigned to the objectives when partitioning the conflict region. Finally, a case study of Baishan Town in Beijing is used to examine and illustrate the dual-objective decision-making method.

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