Table of Content

15 March 2021 Volume 34 Issue 3

  

Analysis of Coupling Characteristics of Microstrip Line on PCB inside Portable Chassis

WU Qilin,TAN Kangbo,LU Hongmin

Electronic Science and Technology. 2021, 34(3):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2021.03.001

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A modeling and simulation analysis method based on model simplification is proposed to solve the problem of electromagnetic coupling interference in the microstrip line of PCB, which is connected to each module in the small interior of the portable chassis and is responsible for the function of information energy transmission and exchange. In this paper, the chassis model is modeled and simplified according to the micro-winding theory. Combined with the electromagnetic model modeling of the PCB inside the chassis and the microstrip line on it, and the adding of corresponding clock signal excitation and load on the microstrip line,the simulation analysis of the coupling characteristics of the microstrip line without PCB is realized. The results show that when the relative spatial position of the interference PCB is perpendicular or parallel, the coupling voltage peaks of the microstrip line are 1.3 mv and 0.5 mv, respectively. The overall change trend is related to the rising and falling edge of clock signal, and the coupling voltage on the vertical and parallel PCB is positively and negatively correlated, respectively.

Experimental Study on Polishing Single Crystal Germanium Flakes with Diamond Suspension Polishing Liquid

YANG Xiaojing,ZHAO Lei

Electronic Science and Technology. 2021, 34(3):  6-12.  doi:10.16180/j.cnki.issn1007-7820.2021.03.002

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In order to study the effect of polishing parameters on the surface quality and material removal of single crystal germanium flakes, single crystal diamond suspension polishing liquid is used to polish the single crystal germanium flakes. The optimal process parameter combination is determined, and the degree and trend of influence of each polishing parameter on the polishing quality is analyzed by orthogonal experiment. Experimental results show that the drop of R_a is 0.848~0.998 μm in 16 experiments. The surface quality of single crystal germanium flakes can be greatly improved if a small particle size single crystal diamond suspension polishing liquid is utilized. The primary and secondary order (primary→secondary) of the influence degree of each parameter on the surface roughness are abrasive grain size, polishing time, loading pressure, spindle speed of polishing head. The optimal parameter combination is shown as: abrasive grain size 0.25 μm; spindle speed of polishing head 70 rpm; loading pressure 8 kg; polishing time 90 min. The effect of abrasive grain size on the surface roughness of the workpiece satisfies the Preston equation. The effect of loading pressure on the surface roughness of the workpiece is consistent with the size effect exhibited by the single crystal germanium (111) crystal plane, and the effects of polishing parameters on the material removal of the workpiece meet the Seok material removal rate model.

Two Degrees of Freedom Control Structure for One Classes of Unstable Process with Time-Delay

ZHU Jingxiu,ZHANG Wei,WANG Yagang

Electronic Science and Technology. 2021, 34(3):  13-18.  doi:10.16180/j.cnki.issn1007-7820.2021.03.003

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In chemical plants and industrial plants, there are problems of uncontrollable first-order time-delay unstable system. In view of this problem, an improved scheme of two-degree-of-freedom controller is proposed in this study. The main idea of the improved scheme is to change the disturbance controller to the PID controller form with leading lag filter while keeping the controller form and algorithm of the set value tracking controller in the original scheme unchanged. Meanwhile, the parameters are tuned based on the direct synthesis method. Finally, the parameter value is selected in accordance with the best compromise between robust stability and load rejection performance. The simulation results show that the proposed scheme significantly improves the system performance and robust stability compared with other schemes. In addition, applying this solution to an isothermal chemical reactor in Example 2 also obtaines satisfactory results.

Study on Radiation Response Characteristics of Internal Cables of Frequency Equipment

HE Yue,ZHANG Jianhua,CHEN Yan,HAN Chunyong,SHI Yunlei,SHAO E

Electronic Science and Technology. 2021, 34(3):  18-21.  doi:10.16180/j.cnki.issn1007-7820.2021.03.004

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There are a large number of cables connecting each subsystem and external system inside the frequency-using equipment. In external electromagnetic interference environment, the electromagnetic energy may penetrate through the device casing and be coupled into the device, thereby generating a coupling voltage on the connection cable inside the device and impairing the device performance. In view of this problem, the finite difference time-domain method is used to simulate the housing and internal environment of the chassis. After briefly modeling, the single line, twisted pair line and coaxial line are set up in the cabinet, and the strong electromagnetic pulse is set up outside the cabinet to study the coupling characteristics of the cables under strong radiation interference. The results showed that the coupling voltage of twisted pair is relatively large, followed by single line, and the peak value of both is relatively close. Because of the shield layer, the coupling voltage of coaxial line is much smaller than that of twisted pair and single line.

Influences of Historical Rate of Interest on the Evolutionary Joint Production Game in Complex Networks

WU Fengyan,LIU Gequn,TAO Feng,GU Dongqing,LIU Xiaokun,ZHANG Wei

Electronic Science and Technology. 2021, 34(3):  22-27.  doi:10.16180/j.cnki.issn1007-7820.2021.03.005

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Researching on the cooperative behavior of independent individuals in evolutionary games has always been a challenge.In view of the problem of cooperative evolution, the effect of memory in strategy updating on the emergence of cooperation in joint production game is studied in this paper. The memory factor u is introduced, and the weighted average return of interest in the nearest two rounds is adopted as a basis for strategy update. Then, Fermi dynamics is used to update strategies by pairwise-comparison. Monte Carlo simulation is applied to analyze the relationship between cooperative rate and profit coefficient under the effect of memory factor and fixed cost, and the evolution curve of cooperative rate over time. The relationship between network mechanism and cooperative rate under the memory factor are analyzed. The proposed study finds that the increase in cooperative rate is positively related to the value of memory weight. Additionally, increasing the effect of historical memory can significantly promote group cooperation and reduce the threshold of profit coefficient required for stable fraction of cooperators to appear. This law is also universal on BA network, ER stochastic network and two-dimensional lattice network.

Circuit and System Design for Assisting Virtual Reality with Data Glove and Electric Stimulation Tactile Enhancement Feedback

LI Zhaoji,WANG Haipeng,RUAN Weihua,HUANG Shuhao

Electronic Science and Technology. 2021, 34(3):  28-36.  doi:10.16180/j.cnki.issn1007-7820.2021.03.006

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In view of the shortcomings of low accuracy, large size, and poor wearability of current virtual reality human-machine interaction devices, this study proposes a new type of assisted VR device for gesture recognition and virtual reality human-machine interaction. The system includes a glove consisting of a set of flex sensors and a nine-axis motion attitude sensor, and a wrist strap based on functional electrical stimulation. The data glove system transmits the data through wireless communication and these data is calculated in the attitude program algorithm on the computer. The results are used to control the hand posture constructed in VR scene in real time. The collision algorithm in the VR scene is adaopted to predict the force haptic value generated by the hand colliding with the object in the scene. Finally, the wireless transmission to the FES stimulation wristband generates different levels of stimulation pulses to assist in completing the force and tactile control of the hand, thereby achieving the effect of human-computer interaction. The measured experimental results show that the average recognition accuracy of a single finger of 5 healthy volunteers is 94.7%±1.3%. The FES wristband can provide a current output of 0~30 mA and a wrist joint strength control with a maximum torque of 1.8 N·m, and the action delay time is 20 ms.

Digital Image Composition Optimization Based on Salient Feature Algorithm

SHAO Hang,WANG Yongxiong,QIN Yulong

Electronic Science and Technology. 2021, 34(3):  36-42.  doi:10.16180/j.cnki.issn1007-7820.2021.03.007

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Image composition is an important factor in the digital image aesthetic quality. Existing computer optimization algorithms have a number of shortcomings, such as visual imbalance and poor integrity. Therefore, this paper proposes a novel composition optimization algorithm based on the deep learning model. This algorithm combines salient features with improved visual balance to achieve composition optimization that is more in line with image aesthetics. The deep convolutional neural network is based on VGG-16, weighting two loss functions and averaging image pixel values. After training, the network could achieve end-to-end saliency regression without any pre-processing or post-processing. Comparative experiments and quantitative verification results demonstrate that compared with the current traditional optimization approaches, the proposed algorithm has obvious advantages in improving visual balance. The processed image has a significantly improved sense of balance, which is more in line with the principles of aesthetic evaluation and visual perception.

Research on Transformer Fault Diagnosis Based on Bayesian Network

TONG Zhaojing,QIN Zini,ZHAO Yunxing,LU Tong,ZHENG Quan

Electronic Science and Technology. 2021, 34(3):  43-47.  doi:10.16180/j.cnki.issn1007-7820.2021.03.008

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In the traditional transformer fault diagnosis ratio method, there are problems that the ratio code is too absolute and early latency failures cannot be found in time. In view of these problems, the improved non-coding ratio method and the type of transformer fault are used as the Bayesian Network nodes, and the improved search strategy and scoring function are employed to establish a transformer fault diagnosis model based on Bayesian network. The on-line fault diagnosis system of transformer based on LabVIEW is established, which realizes the functions of data acquisition, fault reasoning and historical information inquiry. Finally, the experiment proves that the system can not only effectively improve the efficiency of transformer fault diagnosis, but also detect the fault in advance to extend the service life of the transformer, and provide strategic support for the safe and stable operation of the transformer.

Inter-Subject Recognition of Cognitive Workload Based on Ensemble SDAE and EEG

ZHENG Zhanpeng,YIN Zhong

Electronic Science and Technology. 2021, 34(3):  48-53.  doi:10.16180/j.cnki.issn1007-7820.2021.03.009

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Assessing the operator's cognitive workload status in a human-machine system based on EEG signals can effectively prevent the operator's performance from degrading. This study proposes a novel inter-subject CW classifier, E-SDAE, to adapt the variations of the EEG feature distributions across multiple subjects. The E-SDAE includes two cascade-connected modules: high level personalized feature abstractions and decision fusion. The feature filters employ the base learner SDAE to abstract the EEG features from a group of individuals. The supervised CW classifier exploites the random characteristics of ELM to fuse the filtered EEG abstractions under the implementation of Q-statistics. The classification rate achieves 0.635 3 and 0.674 7 for Task 1 and Task 2, respectively, and are significantly better than several conventional CW estimators. The time complexity calculation results show that the computational workload of the E-SDAE is also acceptable for high-dimensional EEG features.

Research on Settlement Characteristics of Ballasted Ballast Based on Discrete Element and Finite Element Coupling

WANG Tong,WANG Lihua,CHEN Jiaming,LI Xianzeng

Electronic Science and Technology. 2021, 34(3):  53-59.  doi:10.16180/j.cnki.issn1007-7820.2021.03.010

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With the development of railway technology in the direction of high-speed and heavy-load, the research on the railway has become more and more significant. The relationship between the sleeper settlement under stable action and the ballast particle movement under the sleeper is analyzed in the proposed study. The method of coupling finite element and discrete element is utilized to study the sleeper settlement and track bed settlement. A 500 mm×230 mm×160 mm simplified sleeper cuboid model with a reduction ratio of 8∶1 is established by using finite element software, and the element nodes of the sleeper are extracted. The discrete element replacement of node coordinates is implemented through the discrete element software EDEM API to construct the sleeper discrete element model, and uses spherical particles to splice ballast particles of different shapes to complete the sleeper-track bed discrete element model. The discrete-element software is adopted to build the sleeper-track bed shrinkage model. At the same time, a test model of the same size as the sleeper model is established, and the validity and reliability of the sleeper-track bed model was determined through comparison and verification. The sleeper and track bed settlements under different excitation frequencies are analyzed, and the sleeper settlement law is obtained. It is determined that the sleeper settlement reaches the maximum when the excitation frequency reaches 36 Hz during the stabilization process. The relationship between the sleeper settlement and the stabilization operation time is obtained. As the stabilization process proceeds, the track bed settlement increases, and the settlement effect in the area directly below the sleeper is better.

Modeling of Combustion Chamber Temperature Model of Combined Cycle Unit Based on Elman Neural Network

DOU Zhengli,WANG Yagang

Electronic Science and Technology. 2021, 34(3):  60-64.  doi:10.16180/j.cnki.issn1007-7820.2021.03.011

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The combustion chamber temperature model of a gas-steam combined cycle unit is nonlinear and strongly coupled, so it is difficult to establish an accurate process control model.To solve the problem, an Elman neural network-based combustion chamber temperature model is proposed in this study. This model uses the output response under different inputs as training set data, and uses the advantage of Elman neural network to approximate non-linear systems with arbitrary accuracy to train Elman neural network. The BPTT algorithm is adopted to back-propagate errors over time, and the SGD algorithm is utilized to optimized network weights. The experimental results show that each index is better than the original transfer function model. The ITAE index of the Elman neural network model under the unit step input signal and the unit ramp input signal are 16.103 4 and 8.990 1, respectively, and the errors of the outputs tracking inputs are 0.039% and 0.035%.

Analysis of VFTO Field Measured Waveform Based on Fast Fourier Transform

CHEN Weiren,ZHANG Wenbin,WANG Lizhe,LI Yincheng,QIAO Yuning

Electronic Science and Technology. 2021, 34(3):  65-70.  doi:10.16180/j.cnki.issn1007-7820.2021.03.012

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When the frequency of the VFTO generated inside the GIS is consistent with the resonance frequency of the winding-type equipment, resonance overvoltage will be generated in the equipment and threaten the safe operation of the equipment. Therefore, it is necessary to analyze the spectral characteristics of the VFTO signal. In this study, a fast Fourier transform is proposed to perform spectrum analysis on VFTO waveform data generated when a field-disconnected isolator is closed. This study first introduces the principle of fast Fourier transform and the feasibility of VFTO spectrum analysis in detail, and describes the measurement system and experimental environment. From the result analysis, it can be found that the frequency component of the field measured VFTO signal is consistent with the frequency component proposed in the IEC 60071-1∶2006 standard. The results verifies the feasibility of performing fast Fourier transform on the spectrum analysis of VFTO signals, and indicates the great applicability in practical engineering projects.