Loading...

Table of Content

15 April 2020 Volume 33 Issue 4
  
    Research on Test Techniques for Shielding Effectiveness of Undermoded Enclosure in Reverberation Chamber
    PENG Guanghui,ZHOU Zhongyuan
    Electronic Science and Technology. 2020, 33(4):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2020.04.001
    Abstract ( 372 )   HTML ( 229 )   PDF (1031KB) ( 67 )  
    Figures and Tables | References | Related Articles | Metrics

    Due to the non-uniform distribution of electromagnetic field in undermoded enclosure, the measurement results of the shielding effectiveness are related to the position. Therefore, it is necessary to use a probe or a monopole antenna for multi-position measurement which is cumbersome. In this study, the long-wire antenna was used to measure the shielding effectiveness of the enclosure under the undermoded state, and compared with the monopole antenna measurements. The free-space reflection coefficient S11 of the antenna was measured in anechoic chamber. The shielding effectiveness of the shielding shell was measured by different antennas in the reverberation chamber, and the cavity resonance characteristic was analyzed with S22. The experiment results showed that the long-wire antenna had better broadband matching characteristic than the monopole antenna, and the measured shielding effectiveness could better reflect the resonant characteristics of the enclosure, which provided guidance for shielding effectiveness evaluation of enclosures and had engineering application value.

    Application Research of Microstrip Antenna Based on Polystry Dielectric Substrate
    ZHANG Qiukui,YI Yingping,ZHAO Jiran,XING Wei
    Electronic Science and Technology. 2020, 33(4):  6-12.  doi:10.16180/j.cnki.issn1007-7820.2020.04.002
    Abstract ( 248 )   HTML ( 13 )   PDF (1482KB) ( 44 )  
    Figures and Tables | References | Related Articles | Metrics

    For the problem that the traditional patch antenna detection frequency is limited (2~35 GHz) and the detection result is not obvious due to the low gain, a solution for constructing a microstrip antenna using polystyrene as a dielectric substrate was proposed. On the basis of the theory that the dielectric material glass microfiber is used as the dielectric substrate, a microstrip antenna model was constructed by using polysty as dielectric substrate. Based on the classical antenna theory, the size of radiation patch and dielectric substrate was calculated. Polysty was built as the model of dielectric substrate based on HFSS. According to the characteristics of microstrip antenna, the parameters of microstrip antenna designed in theory were optimized, and the optimal size of microstrip antenna at 1 GHz was obtained. The results showed that the center frequency of Polysty microstrip antenna as dielectric substrate colud reach 1 GHz, with high gain and wide detection angle range.

    Resilient Event-Triggered Control of Load Frequency Control for Multi-Area Power Systems Against DoS Jamming Attacks
    LIU Ximao,ZENG Yangyang
    Electronic Science and Technology. 2020, 33(4):  12-17.  doi:10.16180/j.cnki.issn1007-7820.2020.04.003
    Abstract ( 288 )   HTML ( 9 )   PDF (892KB) ( 37 )  
    Figures and Tables | References | Related Articles | Metrics

    Focusing on the scenario that the communication network of load frequency control for multi-area power systems is bandwidth-constrained and subject to Denial-of-Service attacks, the problem of the co-design for resilient event-triggered communication scheme and controller was investigated in this study. As DoS parameter is well known, a resilient event-triggered communication scheme was proposed, which could ease the pressure on network bandwidth and eliminated the impact of DoS attacks. In addition, a switched time delay system model was also formulated. The system stability was analyzed by using the piecewise Lyapunov function, and a co-design method for triggered parameter and controller was designed. Finally, the effectiveness of the proposed method was demonstrated with a two-area power system.

    Face Recognition Algorithm Based on Deep Learning and Feature Fusion
    SI Qin,LI Feifei,CHEN Qiu
    Electronic Science and Technology. 2020, 33(4):  18-22.  doi:10.16180/j.cnki.issn1007-7820.2020.04.004
    Abstract ( 454 )   HTML ( 17 )   PDF (789KB) ( 65 )  
    Figures and Tables | References | Related Articles | Metrics

    The convolutional neural network performed well on face recognition, but the extracted facial feature ignores the local structure features of the face. In order to address this problem, a novel method was proposed, which was based on deep learning and feature fusion. This algorithm made the extracted facial features more comprehensive by using a combination of local binary pattern information and original image information as the input of SDFVGG network, which was a neuralnetwork fusing shallow and deep features of VGG network. Experimental results on the CAS-PEAL-R1 face database demonstrated that the proposed algorithm was very effective for improving the accuracy of face recognition, and achieved a maximum face recognition rate of 98.58% which was better than traditional algorithms and general convolutional neural networks.

    Solid-atom Hybrid System Based on Near-field Diffraction of a Thin Metal Circular Disk
    NIE Zhifeng,WANG Zhengling
    Electronic Science and Technology. 2020, 33(4):  23-28.  doi:10.16180/j.cnki.issn1007-7820.2020.04.005
    Abstract ( 293 )   HTML ( 4 )   PDF (1015KB) ( 20 )  
    Figures and Tables | References | Related Articles | Metrics

    In order to realize the confinement of cold atoms on the surface of nano-devices and thoroughly study the propagation law of disk vector diffraction in near field, the diffraction of the thin met al disk by a linearly polarized plane wave is studied by the finite element method. It was found that in the diffraction field, there was not only the incident field in the original polarization direction, but also the intensity distribution in the other two vertical directions. On this basis, A hybrid system of a thin met al disk coupled with atoms was proposed. A subwave well formed by a thin met al disk vector diffraction in the near field, which could trap the small number of cold atoms within 100 nanometers. The trapped distance and volume of the potential well could be controlled by changing the parameters of the disk. These results provided a new hybrid system scheme for micro-nano optical devices and atomic physics.

    Research on Bearing Failure Signal Generation Based on Generative Adversarial Networks
    TONG Bo,LIU Tao,LIU Chang
    Electronic Science and Technology. 2020, 33(4):  28-34.  doi:10.16180/j.cnki.issn1007-7820.2020.04.006
    Abstract ( 269 )   HTML ( 8 )   PDF (1374KB) ( 40 )  
    Figures and Tables | References | Related Articles | Metrics

    In the field of data-driven mechanical system fault diagnosing, there have been many advances in feature extraction and diagnosis models. But in the whole set of diagnostic processes, the lack of failure signals has always been an inevitable problem in diagnosis. Therefore, combined with the GAN model which was effective in the field of image processing, the probability distribution between the generated signal and the real signal were taken as the selection basis of the partial hyperparameter, and the normal phase signal of the bearing was taken as the input of the model. The bearing simulation signal was used as the target of generation, and the failure signal was generated in combination with the mechanical characteristics of the normal stage and the fault characteristics of the simulation signal. Finally, the proposed signal was proved closer to the true failure signal than the simulated signal by means of the general distribution, envelope spectrum, kurtosis and full-life fitting curve of the margin feature.

    VSC-HVDC System with Improved Deadbeat Control when Voltage is Unbalanced
    FU Ziyi,DU Tianyu
    Electronic Science and Technology. 2020, 33(4):  35-42.  doi:10.16180/j.cnki.issn1007-7820.2020.04.007
    Abstract ( 247 )   HTML ( 5 )   PDF (1486KB) ( 30 )  
    Figures and Tables | References | Related Articles | Metrics

    In the case of unbalanced grid voltage, the output power and DC bus voltage of the VSC-HVDC will induce double frequency fluctuation, which affects the stable operation of the system. Aiming to solve the problem, the improved deadbeat control strategy for flexible DC transmission systems under voltage imbalance was studied. The positive and negative sequence reference current expressions were derived by taking the instantaneous active power fluctuation component as zero. Aiming at the control delay of the traditional deadbeat control algorithm and the poor robustness of the change of the inductance parameters on the AC side, an improved deadbeat control strategy was proposed. The control strategy used Lagrangian interpolation to predict the reference current at the next sampling time, then linearly predicted the grid voltage and nonlinearly predicts the grid side current. Finally, the corresponding simulation model was built by MATLAB/Simulink platform. The simulation results proved the correctness and effectiveness of the control strategy.

    Velocity Kinematics Analysis and Simulation of 5-DOF Hybrid Engraving Machine
    ZHANG Daoyi,SAN Hongjun,CHEN Jiupeng,LI Pengfei,XIONG Binzhou
    Electronic Science and Technology. 2020, 33(4):  42-49.  doi:10.16180/j.cnki.issn1007-7820.2020.04.008
    Abstract ( 218 )   HTML ( 6 )   PDF (1253KB) ( 23 )  
    Figures and Tables | References | Related Articles | Metrics

    5-DOF hybrid robot has become an important research direction because of its advantages of both serial and parallel robots. In the process of controlling the 5 degrees of freedom and the series engraving machine, solving the transmission of velocity and acceleration between the input and the end position is the key point and difficulty of the research. In this paper, the degree of freedom of the carving machine was analyzed by the mechanism topology theory. Then the kinematics of the end of the carving machine was inversely analyzed by the vector method. The kinematics of the slider of the carving machine was analyzed by the derivation method. Finally, the validity of the speed kinematics analysis and the effectiveness of the algorithm were verified through MATLAB and ADAMS simulation analysis. This result provided a reference for the actual control programming of the 5-DOF hybrid robot.

    Connected Domain Label Detection Algorithm for Multi-target Lens
    XIE Zhixuan,YAO Hongbing,FAN Ning,CHEN Feng
    Electronic Science and Technology. 2020, 33(4):  50-54.  doi:10.16180/j.cnki.issn1007-7820.2020.04.009
    Abstract ( 297 )   HTML ( 5 )   PDF (824KB) ( 50 )  
    Figures and Tables | References | Related Articles | Metrics

    A multi-target connected domain labeling suitable algorithm for FPGA was proposed in the study. By making a special mark value at the edge of the image during the first scanning, the algorithm extracted ring inner region with inner and outer double-layer contours object to separate the close objects for multi-target detection. The scheme adopted a single pixel-by-pixel scanning method to perform one scanning of the image, and could accomplish the mark of connected regions and the sorting of equivalent tables. Experimental results showed that for an image with the size of M×N, without calculating the recursive time of the equivalent table, multiple targets could be identified after M×N×2 clock cycles. In addition, parameters including the area and the outer rectangle corresponding to each target were finally obtained.

    Study on Internal Flow Field and Separation Characteristics of Two-Phase Cyclone Separator
    YANG Yanbin,HE Wei,GUO Yanjun,ZHAO Hao,MU Yaya
    Electronic Science and Technology. 2020, 33(4):  55-60.  doi:10.16180/j.cnki.issn1007-7820.2020.04.010
    Abstract ( 208 )   HTML ( 2 )   PDF (1284KB) ( 23 )  
    Figures and Tables | References | Related Articles | Metrics

    The two-phase cyclone separator can complete concentration of the slurry and liquid clarification. In order to explore the internal flow field and separation characteristics of the two-phase cyclone separator, the three-dimensional flow field inside the two-phase cyclone separator was numerically simulated by Fluent of the CFD software using the RNG k-ε turbulence model. Then, the distribution of parameters such as the pressure, velocity, volume distribution, turbulent flow energy, and turbulent dissipation rate were obtained. The results showed that the internal radial velocity of the two-phase separation cyclone gradually increased from the center to the outside, and gradually decreased approaching the separator wall, showing an “M” type hump distribution. The axial velocity was symmetrically distributed and the maximum value appeared at the overflow opening and the bottom opening. From the flow trajectory of the ore particles and water inside the cyclone, it could be seen that after the slurry turbid liquid entered the cyclone separator from the tangential inlet, the ore particles and water rotated at high speed inside the cyclone separator to form an external swirling flow and internal swirling. The heavier density of the ore particles flowed out from the lower bottom opening, and the lighter density water flowed out from the upper overflow opening. The simulated two-phase separation efficiency reached 86.93%.

    Research on Fog Removal Based on Dark Primary Color Optimization Algorithms
    LU Huan
    Electronic Science and Technology. 2020, 33(4):  61-65.  doi:10.16180/j.cnki.issn1007-7820.2020.04.011
    Abstract ( 229 )   HTML ( 3 )   PDF (837KB) ( 25 )  
    Figures and Tables | References | Related Articles | Metrics

    In the traditional dark-primary prior dehazing algorithm, the fogging effect in some scenes could not meet the assumption of dark primary color a priori, which leaded to poor dehazing; effect. In this paper, an improved dehazing algorithm was proposed based on the above results. Firstly, the atmospheric scattering model was established according to McCartnet’s theory. Then the transmission map was roughly estimated according to the dark channel prior theory. The tolerance parameter was introduced and the threshold was set to recalculate the transmission map of the high light regions. To achieve self-adapted function of transmission map in high light regions. In order to restore the dark color of the image, an improved linear adjustment method was applied to adjust the brightness of the image. The experimental results showed that compared with the original algorithm, the improved algorithm could effectively estimate the atmospheric light value and reduced the color distortion of the high light regions. The restored image could maintain sufficient brightness without losing the details of the image, and the visual effect was remarkable improved.

    Speed Feedback and Incomplete Differential PID Control of Pneumatic Proportional Position System
    SUN Ruifang,ZHANG Xiaolong,LIANG Wenkai,XIE Xiaoquan
    Electronic Science and Technology. 2020, 33(4):  65-70.  doi:10.16180/j.cnki.issn1007-7820.2020.04.012
    Abstract ( 269 )   HTML ( 2 )   PDF (1029KB) ( 36 )  
    Figures and Tables | References | Related Articles | Metrics

    Pneumatic technology has been widely used in various fields. The optimization of pneumatic proportional position control system has been the inevitable trend of development. This study established the mathematical model of the pneumatic proportional position system, drew the Bode diagram of the system and verified its stability. The response time, accuracy and stability of the pneumatic proportional position system were analyzed by introducing velocity feedback and combining with the incomplete differential PID. The simulation results showed that the step response curves of the system with speed feedback and incomplete differential PID correction could reduce the response time by 2.1 s and the steady-state error by 0.22 mm compared with those of uncorrected, ordinary and incomplete differential PID correction. The response time and steady-state error decreased in turn, and the response process was more stable. The incomplete differential PID correction with speed feedback was introduced, so that the sinusoidal tracking error was smaller, the stability was stronger, and the tracking effect was better. Therefore, while the response speed of the system was greatly improved, the accuracy of the system was significantly increased. These results demonstrated that the dynamic and static characteristics of the system were significantly improved.

Download

Monthly,Founded in September 1987
Competent Authorities:
Ministry of Education of the People's Republic of China
Sponsored by:Xidian University
Chief Editor:Liao Guisheng
Executive Editor:Wan Liancheng
Editor:Hei Lei
Editor and Publisher:
The Editorial Department of Electronic Science and Technology
Distribution Abroad:
China Intermational Book Trading Corporation
P.O.BOx 399,Beijing 100044,China
Address:
P.O.Box 375,2 Taibai Road(South),Xi'an 710071,China
Tel/Fax:0086-029-88202440
Website:http://www.dianzikeji.org
E-mail:dzkj@mail.xidian.edu.cn
Unit Price:$20.00