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15 June 2019 Volume 32 Issue 6
  
    Based on Thevenin Equivalence Static Analysis of Excitation Control for Synchronous Generator
    DENG Yapeng,DUAN Jundong,ZHANG Xiaofang,ZHANG Bin
    Electronic Science and Technology. 2019, 32(6):  1-6.  doi:10.16180/j.cnki.issn1007-7820.2019.06.001
    Abstract ( 354 )   HTML ( 14 )   PDF (1327KB) ( 50 )  
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    The power angle of synchronous generator plays an important role in maintaining the safety and stable operation of power system. The static effect of generator excitation control and the difference between the theoretical power angle of generator and the measured power angle of engineering were analyzed in the proposed paper. Firstly, the Thevenin equivalent circuit is used to study the influence of the active power and excitation adjustment circuit on the single-infinity system at constant frequency. Then the steady-state data is used to verify the mathematical relationship. The results showed that the greater the active power of the generator output, the greater the difference between the measured power angle and the theoretical power angle, which affected the judgment of the operating state of the unit and the system. The automatic excitation regulator changed the phase of the terminal voltage while maintaining the constant voltage.

    Particle Swarm Optimization Based PID Controller Parameter Optimization
    DU Meijun,ZHANG Wei,XIE Yalian
    Electronic Science and Technology. 2019, 32(6):  7-11.  doi:10.16180/j.cnki.issn1007-7820.2019.06.002
    Abstract ( 631 )   HTML ( 22 )   PDF (972KB) ( 118 )  
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    Particle swarm optimization is an intelligent algorithm that can achieve better results in the application of PID controller parameter tuning. In order to solve the shortcomings of the premature convergence and slow convergence of the traditional particle swarm optimization algorithm, this paper adopted a method of dynamically adjusting the inertia weight based on the similarity, that was, the closer to the current optimal particle, the smaller the inertia weight value was assigned. Finally, MATLAB was used to simulate the isothermal continuous stirred tank reactor. Compared with the standard PSO tuning method, the improved particle swarm algorithm had a settling time of 230.1 s, which was half the stability time of the conventional particle swarm optimization algorithm of 524.7 s, indicating that the improved algorithm had better parameters optimization for the PID controller.

    Research about Bandwidth Utilization of Static Segment Based on FlexRay Bus
    ZHANG Yugui,HU Xuechen,WANG Yi
    Electronic Science and Technology. 2019, 32(6):  12-16.  doi:10.16180/j.cnki.issn1007-7820.2019.06.003
    Abstract ( 292 )   HTML ( 6 )   PDF (899KB) ( 26 )  
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    In order to improve the bandwidth utilization ratio of the Flexray network, this study analyzed the static segment parameters of Flexray and the length of the message in transmission. To reduce the bandwidth waste resulting from the great difference between mathematical model and static message length, the optimization function of MATLAB and the method of dividing the long messages into two messages of the same length were proposed respectively. This paper illustrated the problem of converting mathematical model of static segment in Flexray network to nonlinear programming.The proposed distribution methods considered the effect of increasing useless bits in the coding process on the entire network. Numerical experiments showed that this method could be further improved based on theoretical maximum utilization of bandwidth.

    An Improved Path Planning Algorithm With Variable Probability Bidirectional RRT
    HU Huimian
    Electronic Science and Technology. 2019, 32(6):  16-21.  doi:10.16180/j.cnki.issn1007-7820.2019.06.004
    Abstract ( 375 )   HTML ( 7 )   PDF (1177KB) ( 50 )  
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    To deal with the problems of slow convergence speed and the irregular searching path of the RRT algorithm, a variable probability search strategy optimization algorithm based on the bidirectional RRT was proposed. This bidirectional RRT algorithm searched different surrounding states of nodes, then extended the target point with different probability strategies. Therefore, this algorithm could rapidly converge to the target in the open environment as well as avoid falling into local minimum. After the initial path search was completed, the irregular route was optimized according to the location of the path node, and the number of turning times during the car driving and the length of the total path were effectively reduced.The multi scene repeated test was carried out in the simulation, and the simulation results showed that this algorithm had a significant improvement in the search speed and path length.

    Single Event Effect Under Total Dose Radiation in Strained Si NMOS Devices
    ZHANG Qian,HAO Minru
    Electronic Science and Technology. 2019, 32(6):  22-26.  doi:10.16180/j.cnki.issn1007-7820.2019.06.005
    Abstract ( 293 )   HTML ( 4 )   PDF (1382KB) ( 27 )  
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    The effect of the total dose radiation on the single event effects of strained Si NMOS devices was investigated by using TCAD simulation. The TCAD simulation model of the 50 nm strained Si NMOS device was constructed by the experimental results comparison. The single event effect of NMOS devices under off-state (Vds=1 V) at the total dose was simulated by the proposed correct model. The experimental results showed that the positive charge of the oxide trap introduced by the total dose radiation increased the body potential, which further exacerbated single event transients in NMOS devices. The drain transient current increased by 4.88% while the drain charge increased by 29.15% at a total dose of 2 KGy, which revealed that the effect of total dose radiation on the single event effect was mainly reflected in the significant increase in the drain charge collection.

    Research on Fault Diagnosis of Analog Circuit Based on Elman Neural Network
    SUN Likuo,WANG Daiqiang
    Electronic Science and Technology. 2019, 32(6):  26-30.  doi:10.16180/j.cnki.issn1007-7820.2019.06.006
    Abstract ( 261 )   HTML ( 7 )   PDF (917KB) ( 30 )  
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    Aiming at the soft fault of analog circuits, a diagnosis method based on improved Elman neural network combined with the improvement of feature vector effectiveness was proposed. This method performed three wavelet analysis on the output signals under different cases to form an eight-dimensional feature vector, which was combined with the improved Elman neural network for classification and diagnosis. Applying the improved Elman neural network to the fault diagnosis of nonlinear analog circuits could improve its diagnostic rate and classification rate.This paper had carried out experimental comparison tests on the diagnostic methods.The results showed that the method improved the diagnostic performance, of which the diagnostic rate and classification rate were 92.5% and 83%,respectively.

    Research on Vehicle Formation Based on Adaptive Control Algorithm
    BI Zaorong,TONG Dongbing,CHEN Qiaoyu
    Electronic Science and Technology. 2019, 32(6):  31-37.  doi:10.16180/j.cnki.issn1007-7820.2019.06.007
    Abstract ( 255 )   HTML ( 4 )   PDF (1263KB) ( 42 )  
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    This paper explored the vehicle formation control problem based on a bioinspired neurodynamics approach. A dynamic model for vehicle formation control was established in the leader-follower framework based on kinematics of each vehicle. According to Lyapunov stability theory, a new adaptive feedback tracking controller was designed to transform the vehicle following problem into the control problem of system error, which was followed by simulation experiments for effectiveness verification. The results showed that the newly designed controller had further improved stability and convergence speed compared to existing feedback tracking controllers.

    An Active Equalization Method for Lithium-ion Battery Pack Based on Additional Battery
    ZHOU Ping,GAO Han,ZHENG Yuejiu,LAI Xin,ZHOU Long
    Electronic Science and Technology. 2019, 32(6):  37-42.  doi:10.16180/j.cnki.issn1007-7820.2019.06.008
    Abstract ( 485 )   HTML ( 5 )   PDF (1561KB) ( 58 )  
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    The series lithium batteries used in electric vehicles will be unbalanced after repeated charge and discharge, resulting in the decrease of battery capacity and life span. In this paper, a non-energy consumption active equalization method based on additional battery was proposed, and the balanced circuit and the equilibrium control strategy were designed. The equalization scheme transferred the energy of the high voltage cell to the additional battery during charging, and further transferred the power of the additional battery to the low voltage cell when discharging, which realized the free storage and transfer of the energy. The principle of equalization circuit and the equilibrium control strategy were analyzed, and the Simcape and Stateflow in MATLAB/Simulink were used to model and simulate the equilibrium circuit and control strategy, respectively. The simulation results showed that the equilibrium control method could realize the equilibrium of the battery pack quickly, and the usable capacity of the battery was improved obviously.

    Analysis of Discharge Parameters Affected by BP Neural Network Predicting Electrode Velocity
    GUAN Sheng,RUAN Fangming,ZHOU Kui,SU Ming,WANG Heng,DENG Di,LI Jia
    Electronic Science and Technology. 2019, 32(6):  43-48.  doi:10.16180/j.cnki.issn1007-7820.2019.06.009
    Abstract ( 280 )   HTML ( 3 )   PDF (1450KB) ( 29 )  
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    The dual-process model of small gap discharge was used to investigate the influence of the change of field intensity and pressure on the internal correlation factors of the discharge gap, and the BP neural network was applied to predict and analyze the influence of the electrode moving speed on the discharge parameters. Based on the electrostatic discharge electrode moving speed effect detector, the electrode moving speed was continuously changed, and the discharge experiment had been repeated several times to obtain and statistically calculated the test data. Meanwhile, BP neural network was used to train and learn the measured experimental data, so as to predict the current rise time and peak current at different speeds and pressures. The results showed that there was no correlation between the rising time of the discharge current and the moving speed of the electrode. According to the new method, the accuracy of peak current at different speeds was higher than that of the actual size. The research results was of great reference value in exploring the law of non-contact electrostatic discharge and the formulation of electrostatic discharge standards.

    Research on Switching Technology of Thyristor and SF6 Switch Capacitor in AVC System
    WANG Canxia,CHNEG Jia,XIAO Xia,SUN Jing
    Electronic Science and Technology. 2019, 32(6):  49-54.  doi:10.16180/j.cnki.issn1007-7820.2019.06.010
    Abstract ( 356 )   HTML ( 3 )   PDF (1141KB) ( 75 )  
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    With the commissioning of the AVC system, the switching of the capacitor in the substation was more frequent. The conventional switching capacitor SF6 switching frequency is low, and it fails to meet the reactive power compensation requirements in the switching gap, limiting the role of the capacitor. In order to solve the above problems, a compound switch structure was proposed, which combined mechanical switching and electronic switching to form a combined switching scheme of thyristor and SF6 switch. The working principle of thyristor & SF6 switching capacitor was introduced and the switch control strategy was analyzed in this paper. Through a reasonable switching strategy, mutual protection of the thyristor and the SF6 switch was realized, so that the thyristor could withstand high voltage when blocked, and also avoided frequent operation of the SF6 switch in the case of high-frequency switching, thereby prolonging the service life of the device. Finally, the rationality and feasibility of the compound switch were verified by PSIM software simulation.

    Malicious Code Detection and Protection Technology of Mobile Phone Based on Android
    YE Zi,LI Ruofan
    Electronic Science and Technology. 2019, 32(6):  54-57.  doi:10.16180/j.cnki.issn1007-7820.2019.06.011
    Abstract ( 378 )   HTML ( 9 )   PDF (1169KB) ( 43 )  
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    With the development of modern communication technology and the development of mobile terminal,Android system breeding a lot of malicious code, due to its own open source.In order to satisfy the requirement of the modern mobile secure, a professional malicious code detection model based on SVM was designed in this paper, realizing a malicious code detection and protection system. The system had been tested by Android mobile phone, which provided better detection accuracy and low false negative rate of malicious code.

    3D Space Path Planning Research Based on Improved Local Search Algorithm
    ZHAO Wei,ZENG Guohui,HUANG Bo,ZHU Shuangxin,LIU Jin
    Electronic Science and Technology. 2019, 32(6):  58-63.  doi:10.16180/j.cnki.issn1007-7820.2019.06.012
    Abstract ( 294 )   HTML ( 8 )   PDF (1674KB) ( 49 )  
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    In robot path planning, the increase of the search area dimension will cause the path search algorithm to not converge or converge for too long time. Aiming at this problem, heuristic function model was established to improve the purpose of optimization based on the improved local search algorithm, integrating the pheromone in ant colony algorithm and potential field factor in the artificial potential field algorithm. The iteration method was used for search path optimization. The selection of path points in three-dimensional space and the establishment of heuristic function model were discussed in detail, and the detailed flow of the algorithm was presented. Finally, through the MATLAB simulation experiment, the results showed when the path planning was carried out based on the improved algorithm, the number of iterations was decreased, the search speed was faster, and the path point trajectory trend was more stable.

    Research on Optimization Management of Electric Vehicle Charging and Discharging
    SHAN Zhifei,SUN Yuxuan,ZHANG Xiang,CHEN Qiang,ZHENG Zhiyi
    Electronic Science and Technology. 2019, 32(6):  64-69.  doi:10.16180/j.cnki.issn1007-7820.2019.06.013
    Abstract ( 340 )   HTML ( 6 )   PDF (1205KB) ( 69 )  
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    With the increasing popularity of electric vehicles, the disordered charging and discharging of electric vehicles will have a great impact on the power system. Firstly, the factors affecting the charging load were analyzed, and the data feature function was established. The function model of electric vehicle had been fitted by least squares method. Secondly, according to the characteristics of the mathematical model, the load of multiple electric vehicles was planned. Then, the multi-objective optimization function was established by the Monte-Carlo algorithm used for constructing the probability process to sample the charging load curve of the electric vehicle from the known probability distribution. Finally, the simulation proved that the proposed model could accurately simulate the access situation of large-scale electric vehicles through a small number of samples. The improvement of the charging and discharging optimization problem of electric vehicles effectively reduced equipment investment, the peak-to-valley difference of disordered charging, and maintained stable operation of the system.

    Design of Water Bath Constant Temperature Control System Based on Chip Microcomputer
    LI Yiping
    Electronic Science and Technology. 2019, 32(6):  69-73.  doi:10.16180/j.cnki.issn1007-7820.2019.06.014
    Abstract ( 386 )   HTML ( 23 )   PDF (1117KB) ( 85 )  
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    Aiming at the instability of water bath temperature, the digital temperature sensor DS18B20 was used to complete the water temperature detection and conversion. SCM STC89C52 controled the heating equipment according to the received signal.The constant temperature range was set and checked by three keys. The actual temperature was displayed by four-digit digital tube and the working state was displayed by one-digit digital tube. Built the hardware circuit of the system, completed the design and debugging of each hardware circuit, wrote the system program, and used Proteus to simulate the experiment. The simulation results showed that the system can control the temperature within the set range and display the real-time water temperature.The detection temperature can be accurate to 0.1 ℃ and the measurement range was 0~100 ℃ and the detection results was stable.

    NBTI Effect and Leakage Power Consumption Based on Cyclic Vector Cooperative Optimization Circuit
    SHI Qichen,ZHANG Jiayang
    Electronic Science and Technology. 2019, 32(6):  74-77.  doi:10.16180/j.cnki.issn1007-7820.2019.06.015
    Abstract ( 281 )   HTML ( 3 )   PDF (1001KB) ( 30 )  
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    When the characteristic size of the transistor is reduced to 45 nm, the reliability of the circuit has become a key factor affecting system design, the main cause of circuit reliability caused by negative bias temperature instability (NBTI) and leakage power consumption, resulting in The aging of the key door is aggravated, and the critical path delay is increased, which eventually causes the chip to fail and affects the normal operation of the system. In order to alleviate the influence of NBTI effect and leakage power on circuit reliability and extend the service life of the circuit, this paper proposed a cyclic vector method for collaborative optimization. In the ISCAS85 reference circuit, used the method of this paper to optimize the experiment, the average delay of NBTI effect was relatively improved at 10%, the leakage power consumption was reduced by an average of 15%, which proved the feasibility of the cyclic vector method.

    Research on Distributed Mobile Phone Signaling Data Acquisition and Analysis Technology
    LI Yuan
    Electronic Science and Technology. 2019, 32(6):  78-81.  doi:10.16180/j.cnki.issn1007-7820.2019.06.016
    Abstract ( 477 )   HTML ( 8 )   PDF (1020KB) ( 48 )  
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    Aiming at the problem of large-scale signaling data storage and real-time analysis caused by the dispersion of the distribution of smart phones, this paper designed a mobile phone signaling data acquisition and analysised technology based on distributed computing. This paper designed a distributed signaling data acquisition technology structure and integrates four distributed databases to realize distributed signaling data storage. In addition, combined with Spark technology, the distributed signaling data analysis module designed in this paper can analyze and integrate the collected signaling in real time. The distributed signaling data acquisition and analysised scheme designed in this paper could be applied to the collection and processing of large-scale mobile phone signaling data, which had certain significance for distributed signaling monitoring.

    Research on Face Recognition Based on Deep Learning
    HU Shaocong
    Electronic Science and Technology. 2019, 32(6):  82-86.  doi:10.16180/j.cnki.issn1007-7820.2019.06.017
    Abstract ( 546 )   HTML ( 19 )   PDF (1220KB) ( 184 )  
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    As one of the contactless biometric methods, face recognition is widely used in many situations. However, the traditional face recognition method can not meet the current demand because of its low recognition accuracy and limited application in many occasions. In this paper, we proposed a deep learning method to achieve facial marker detection and unrestricted face recognition. In order to solved the problem of face marker detection, this paper proposed a layer-by-layer training method for deep convolutional neural networks to help convolutional neural network convergence, and proposes a sample transformation method to avoided overfitting;In order to solve the face recognition problem, this paper proposed a SIAMESE convolutional neural network, which was trained on different parts and scales. Experimental tests showed that the accuracy of ORL and face recognition algorithms reached 91% and 81%, respectively.

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