Table of Content

15 April 2019 Volume 32 Issue 4

  

Research of Face Recognition Method Based on Gabor and SIFT Features

ZHOU Zhu,GAN Yi,SUN Fujia

Electronic Science and Technology. 2019, 32(4):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2019.04.001

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Position variation and illumination interference affect the accuracy and efficiency of face recognition. To solve the problem, a new method of feature extraction combining the Gabor feature and SIFT feature was proposed in this paper. Gabor feature of face images from multiple scales and directions were extracted and divided into sub-images of the same size. The SIFT features were extracted from the partitioned sub-images, and all SIFT vectors of the obtained Gabor features were cascaded as the final feature vectors. Principal component analysis method was used to reduce the dimension of the final eigenvectors, and then the least squares support vector machine was used for training and recognition of images. Experimental results of tests in the FERET face database showed that compared with the traditional single face recognition method, the accuracy of face recognition was 98.1% under the change of position and illumination interference, which proved the effectiveness of the new algorithm.

Research on Fault Tree Analysis Method for Hybrid Uncertainties Using Stochastic Logic Implemented on Field-programmable Gate Arrays

LI Mengfan,ZOU Zihao,SHU Fandi

Electronic Science and Technology. 2019, 32(4):  6-10.  doi:10.16180/j.cnki.issn1007-7820.2019.04.002

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This paper proposed a fault tree analysis method based on stochastic logic,which utilized hybrid fault tree analysis (HFTA) to take into account both objective and subjective uncertainties. In the proposed method, each fault tree gate was translated to its corresponding stochastic logic module and then was implemented on a field programmable gate array (FPGA). The accuracy and performance of the proposed method were compared with the conventional method In the case that the a-clipping confidence level was equal to 0. Because the top event probability cumulative distribution function is basically compatible with the conventional hybrid method,it can be considered that the accuracy of the new method results and the conventional hybrid method is basically the same.

The Design of Wireless Image Transmission System for Balloon-borne Observation System

CAO Yuan,DONG Dengfeng,XU Zhenying,ZHOU Weihu,HE Yang

Electronic Science and Technology. 2019, 32(4):  10-15.  doi:10.16180/j.cnki.issn1007-7820.2019.04.003

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In order to achieve lightweight and high-speed wireless transmission of images in the tethered balloons observation system, hardware architecture ZYNQ+AD936 orthogonal frequency division multiplexing technology was adopted. The digital interface with AD9361 RF front end, the ARM part data channel with ZYNQ, as well as the physical layer of baseband processor based on IEEE802.11a standard could be realized through FPGA part of ZYNQ. The ARM section ran the Linux operating system, where the development of AD9361 configuration applications, physical layer management, and data interaction with the host computer and the camera could be achieved. The introduction of wireless image transmission system accomplished the point to point wireless image transmission between the air balloon observation platform and the ground control center, enhancing the reliability of tethered balloons target monitoring observation system. The proposed communication system combined the merits of software radio system, flexible configuration and orthogonal frequency division multiplexing spectrum of high utility and anti-multipath effect, thus it could be applied to a variety of complex environments with the tethered balloon observation system.

Adaptive Acoustic Emission Noise Elimination and Bearing Fault Diagnosis

ZHU Wangchun,CHENG Hao,GAO Haiying

Electronic Science and Technology. 2019, 32(4):  16-20.  doi:10.16180/j.cnki.issn1007-7820.2019.04.004

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When acoustic emission signals are analyzed for bearings, environmental noise causes signal energy to fluctuate, resulting in misdiagnosis of late failures. To solve the problem, a spectral subtraction method was introduced to pre-noise the acoustic emission signal to enhance the stability of signal. In view of the lack of processing performance of spectral subtraction for non-stationary signals, spectral subtraction coefficients were modified and genetic algorithm was used to optimize the spectral subtraction coefficients(m, λ) globally. Experiment showed that the adaptive spectral subtraction method could obtain better spectral subtraction coefficients, and the fluctuation of wavelet packet energy feature could be eliminated. After the SVM training for the energy features of various bearing faults, the accuracy rate could reach about 92%.

Dimension Synthesis Method of Suspended Substrate Stripline Filter

LI Gang,HU Xu

Electronic Science and Technology. 2019, 32(4):  20-23.  doi:10.16180/j.cnki.issn1007-7820.2019.04.005

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As for the low precision problem of designing the Suspended Substrate Stripline filter based on empirical formulas, this paper presented a dimension synthesis method of the SSS filter. The equivalent circuit model of the resonant cavity and coupling structure of the SSS filter was established and the influence of the reactance slope of the coupling structure on the resonant cavity was analyzed in detail. Through the full wave simulation, the reactance slope parameters of the coupling structure could be accurately extracted and the physical length of the transmission line cavity was corrected step by step without time-consuming full wave optimization. Finally, A five orders SSS filter with Chebyshev response was designed. The simulation results agreed well with the theoretical results, which verified the validity of the method.

Experimental Study on the Loading Performance of Magnetic Powder Brake

LUO Yimin,GU Yangyang,MAO Yadong,XÜ Yan,XÜ Min,GENG Miaomiao,ZHANG Xiliang,LI Boquan,ZHANG Xin,YAN Youqi

Electronic Science and Technology. 2019, 32(4):  24-28.  doi:10.16180/j.cnki.issn1007-7820.2019.04.006

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In view of the lack of research on the performance of magnetic powder brake in the process of combined loading of load test of elevator load test, the loading performance of magnetic powder brake was studied. Based on the three-phase asynchronous motor test platform, the performance test of the magnetic powder brake loading response time and output torque was carried out. The analysis of the test results was: There was a certain hysteresis in the loading response of the magnetic powder brake. The loading response time was 12.5 s, and the speed of the motor has no effect on the loading response time of the magnetic powder brake. The control voltage of the magnetic powder brake was in the range of 0.3~1.3 V, the input voltage and the output torque are linear. When the control signal of the magnetic powder brake was certain, the greater the speed of the motor, the more stable the output torque of the magnetic powder brake. The experimental results provide the experimental basis for the application of magnetic powder brake in the load replacement device of elevator load test.

Chinese Word Segmentation Based on Joint Training of Heterogeneous Data

JIANG Meng,WANG Ziniu,GAO Jianling

Electronic Science and Technology. 2019, 32(4):  29-33.  doi:10.16180/j.cnki.issn1007-7820.2019.04.007

Abstract ( 379 )   HTML ( 3 )   PDF (490KB) ( 92 )  

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Chinese word segmentation technology is one of the key basic technologies in Chinese information processing. The Chinese word segmentation method based on deep learning model is widely concerned. However, the deep learning model requires large-scale data training to obtain good performance, but the current Chinese sub-word data is relatively lacking and the standards are not the same. This paper proposes a simple and effective method of heterogeneous data processing. Firstly, two artificially-set identifiers are added to different corpus data, and then the processed data is applied to the joint training of Bi-LSTM-CRF Chinese word segmentation model. Experimental results show that the Bi-LSTM-CRF model based on heterogeneous data joint training has better segmentation performance than the single data training model.

Hyperspectral Image Sub-Pixel Mapping Based on Sparse Unmixing of Endmember Dictionary

GU Zhengzhi,WANG Suyu

Electronic Science and Technology. 2019, 32(4):  33-39.  doi:10.16180/j.cnki.issn1007-7820.2019.04.008

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In general, it is difficult to locate the spatial distribution of each endmember in the hyperspectral image. To solve the problem, this study proposed a K-SVD-based spectral unmixing algorithm whose result of the demixing was further used for performing the subpixel location. First, the mixed pixel and pure pixel were distinguished by KNN classification, and then the sparse decomposition correlation theory based on redundant dictionary was used for reference. Based on the standard spectral library, the K-SVD based dictionary training algorithm was used to train the most representative material spectral curves, and the endmember redundancy dictionary was subsequently constructed. The abundances were solved by the sparse decomposition algorithm based on K-SVD. Finally, the obtained abundance coefficient was used to locate the sub-pixel under the two spatial correlation constraints. Experimental results showed that the proposed algorithm had reliable performance for the sub-pixel mapping effects of simulated data and measured data.

New Image Encryption Algorithm Based on DNA and Cellular Automata

WANG Hongda

Electronic Science and Technology. 2019, 32(4):  39-43.  doi:10.16180/j.cnki.issn1007-7820.2019.04.009

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In order to solve the problem of insufficient key space and poor robustness of existing image encryption algorithms, a new image encryption algorithm was designed based on traditional chaotic encryption. The algorithm employed the SHA256 function to calculate the plaintext to further obtain the initial value and key of the system while the scrambling process was eliminated. Image encryption was carried out by the cross-diffusion of the plaintext and cellular automata. The calculation and analysis of related secure indicators showed that the key space reached more than 2 ³²⁰, and it could resist 30% shear attack and various noise attack, indicating that the algorithm displayed a good security and robustness.

An Image Denoising Algorithm Based on Improved Threshold Function Contourlet Domain

WANG Hongchuang,HU Xiaohui,LI Wei

Electronic Science and Technology. 2019, 32(4):  44-48.  doi:10.16180/j.cnki.issn1007-7820.2019.04.010

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ing at the problem of ringing and pseudo-Gibbs caused by the discontinuity of hard threshold function in the Contourlet domain and the problem of image blur distortion caused by constant value compression in the soft threshold function, a Contourlet domain image denoising method based on improved threshold function was proposed.The improved threshold function introduced the idea of exponential smoothing function method to make it continuous, gradual, deviating and high-order conductibility in the Contourlet domain, which overcame the problems of soft and hard threshold functions. In this method, the BayesShrink adaptive threshold estimation was used in the threshold estimation part, which could accurately determine the threshold size and solved the phenomenon that traditional fixed threshold estimation overkill the transform coefficient. Compared with the traditional denoising methods, the improved image denoising method proposed in this paper had better denoising effect in the objective evaluation criteria including peak signal-to-noise ratio, root mean square error and image enhancement factor.

Research on UAV Application of Magnetic Resonance Coupling Wireless Power Transmission System

SUN Jing,ZHU Jun,LIU Hua,WANG Canxia

Electronic Science and Technology. 2019, 32(4):  49-53.  doi:10.16180/j.cnki.issn1007-7820.2019.04.011

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ing at the endurance of UAV, this paper adopted a method of installing a charging platform on a transmission tower and MCR-WPT to install the transmitting coil and the receiving coil on the charging platform and the UAV respectively. For UAV charging,the output power and transmission efficiency of the MCR-WPT system were required to be improved. In this paper, differential evolution algorithm was used to optimize the transmission distance, resonant frequency and load resistance of the two-coil MCR-WPT system. It could be seen that the output power of the dual coil MCR-WPT system had been improved and the transmission efficiency had increased from the original 0.40 to 0.68,which verified the effectiveness of the optimization method.

Spectrum Allocation with Multi-Objective Optimization based on Immune Algorithm in Cognitive Radio Networks

GAO Yang,HAN Ren,WANG Qingyun

Electronic Science and Technology. 2019, 32(4):  54-59.  doi:10.16180/j.cnki.issn1007-7820.2019.04.012

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Too many secondary users working on the same channel in a cognitive radio network will lead to serious interference to the network. Therefore, how to increase the network throughput while increasing the number of serviceable users in the network has become a research focus in recent years. An improved multi-objective immune algorithm was proposed to solve the problem which was addressed with respect to both spectrum efficiency and network throughput. Meanwhile, an antibody encoding that was suitable for solving the problem was designed. After obtaining the Pareto optimal solutions, the contrast test was conducted with the NSGA-II. The simulation results validated that the proposed strategy performed better in searching pareto optimal solutions and satisfied the network requirements of spectrum allocation in various cases.

Improved Random Forest Algorithm Based on Spark

SUN Yue,YUAN Jian

Electronic Science and Technology. 2019, 32(4):  60-64.  doi:10.16180/j.cnki.issn1007-7820.2019.04.013

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For the classical random forest algorithm based on single machine couldn't meet the demand of dealing with massive data, an improved random forest algorithm based on Spark was designed and implemented by using Spark distributed memory computing technology. Firstly, after calculating the importance of features the features were divided into public features, unique features, and non-important features;. Then, randomly features were selected in each feature subspace in order and proportion. Finally, the experiment was performed through Spark clusters to analyze the improved classification performance, speedup ratio and efficiency of the random forest algorithm. The result demonstrated that the improved algorithm could improve the efficiency of random forest construction and could be used to solve the massive data mining problem with good scalability.

Preparation of Liquid Exfoliation of MoS₂ Nanosheets Dispersion

LIU Chenrenlang,LI Peizhen,CHEN Long,AN Qi

Electronic Science and Technology. 2019, 32(4):  64-67.  doi:10.16180/j.cnki.issn1007-7820.2019.04.014

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In this paper, nano-flaky dispersion was prepared by liquid exfoliation from bulk material. The concentration of the dispersion was determined by UV-Vis spectra, and the effects of ultrasonic power, ultrasonic time, initial concentration of molybdenum disulfide on the concentration of nano-flakes dispersion were explored. Experimental data showed that when the ultrasonic power was 350 W, the ultrasonic time was 48 h, and the initial concentration of molybdenum disulfide was 10 mg/mL, the concentration of the nano-flakes could reach 0.16 mg/mL. During the stripping process, the addition of PVP could effectively avoid the problem of poor stability of the dispersion due to self-agglomeration of the nanoflakes, and the resulting dispersion of molybdenum disulfide nanoflakes could be stably stored for more than two months. Meanwhile, the addition of PVP increased the concentration of MoS₂/PVP dispersion to 0.42 mg/mL.

A Multi-environmental Traffic Sign Recognition Model

YAN Maosen,CHEN Jiaqi

Electronic Science and Technology. 2019, 32(4):  68-72.  doi:10.16180/j.cnki.issn1007-7820.2019.04.015

Abstract ( 441 )   HTML ( 5 )   PDF (600KB) ( 41 )  

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Traffic sign recognition plays an important role in autopilot and assisted driving systems. However, most related studies were limited to the identification of daylight scenarios. If these models were applied in night, the difference of light intensity would lead to a significant decrease in recognition accuracy. In order to solve this problem, this paper proposed a light intensity classification model, which used different methods to identify the signboard according to the difference of light intensity to ensure excellent recognition rates in night. Firstly, the model divided the scene and processed the ROI by different methods. And then, eigenvectors were trained by KNN and SVM. Finally, the trained eigenvectors could identify the type of a sign. Experiments proved that the accuracy rate of this model in different environments was as high as 98.1%.

Deadbeat Direct Torque Control of Permanent Magnet Synchronous Motor Based on Full-Dimensional State Observer

SUN Ruining,DING Yiming,LIANG Jintao

Electronic Science and Technology. 2019, 32(4):  72-76.  doi:10.16180/j.cnki.issn1007-7820.2019.04.016

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The traditional direct torque control of permanent magnet synchronous motor has the disadvantages of large flux amplitude and torque ripple. This thesis proposes a scheme of no-beat direct torque control based on state observer. The scheme can eliminate the problem of the initial flux linkage error and the influence of the motor parameters on the traditional observation method by constructing a full-dimensional state observer to observe the amplitude of the stator flux linkage. In addition, for the real lag phenomenon generated by the traditional control system, the thesis proposes to calculate the required voltage vector one cycle ahead of time, realising the deadbeat control of Torque and flux linkage. The results showed that the proposed dead-beat control based on full-dimensional state observer can suppress the flux linkage and torque ripple better and has good control performance.

A Dispatch Model for Wind Power and Pumped-storage System Based on Demand Response

ZHOU Zhengwei,HAO Yaqun,ZHANG Xueying

Electronic Science and Technology. 2019, 32(4):  77-81.  doi:10.16180/j.cnki.issn1007-7820.2019.04.017

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Aiming at the problem that large scale integration of wind generation would adversely affected the stable operation of power grids, a new wind power consumption model for power grids was proposed based on a recent user-side power load forecast and the real-time pricing forecast. With the goal of minimizing the cost of electricity generated by the wind power and pumped-storage combined system, the choice of the optimal self-elasticity coefficient and mutual elasticity coefficient was determined in the process of its target solution. The electric consumer was guided to achieve the load transfer based on the demand price elasticity of the real-time pricing. Considering the elasticity constraints of the user-side electricity price, the genetic algorithm was applied in the proposed method. The simulation results showed that the load valley-to-peak difference could be reduced if the demand side resources actively participated in optimal operation, which could facilitate the stable operation of the system and reduce the power generation cost, so as to improve the economy of the joint system.

Research on Obstacle Detection of Transmission Line Corridor Based on 3D Laser Radar Technology

WANG Songbo,LI Maxiao,LI Hairui,MENG Qingyi,JIANG Mingxi

Electronic Science and Technology. 2019, 32(4):  81-84.  doi:10.16180/j.cnki.issn1007-7820.2019.04.018

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The traditional manual inspection method of transmission line has the problems of low efficiency and high expend. Hence, based on the 3D laser radar technology and combined with the unmanned aerial vehicle, this paper designs and develops a set of obstacle detection of transmission line corridor with high automation degree. The system can detect and judge the safety distance between the transmission line and the surrounding obstacles by means of the pre-processing and the classification extraction of the point cloud data, and the threshold comparison of the measured distance. The test and analysis results show that the system can accurately measure and judge the distance between the obstacle and the transmission line, reducing expend of the traditional manual inspection, and providing help for the detection of obstacles in the transmission line corridor.

Monitoring and Evaluation of Physical and Mental Quality of Middle School Students Based on Big Data Analysis

LI Xinyue,LI Yujie

Electronic Science and Technology. 2019, 32(4):  85-90.  doi:10.16180/j.cnki.issn1007-7820.2019.04.019

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It is difficult for the traditional physical and mental quality education of the school to comprehensively analyze and evaluate the physical and mental quality of middle school students, enhance the enthusiasm of students to exercise in physical and mental, let teachers and parents know the physical and mental quality of students in real time, and provide personalized guidance for students’ physical and mental quality training and physical examination. This paper adopted big data analysis technology to study the evaluation methods of physical and mental quality of middle school students and the recommendation methods of personalized exercise programs, and designed and implemented the physical and mental quality monitoring and evaluation system for middle school students based on mobile terminals, Qingyue Quan, which provided services for students, teachers and parents respectively. The results of the fixed-point test of Qingyue Quan showed that it solved the existing problems and met the new needs of middle school students’ physical and mental quality education.

Power Flow Calculation of AC/DC Hybrid Micro Grid with Weighting Coefficient

YI Ming,WANG Shilong,FAN Yumeng

Electronic Science and Technology. 2019, 32(4):  90-95.  doi:10.16180/j.cnki.issn1007-7820.2019.04.020

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In the power flow calculation of AC/DC hybrid micro grid under droop control, the diagonal elements of the Jacobi matrix are zero and the matrix cannot be solved. In response to these phenomena, an improved power flow calculation algorithm with weighting coefficient was proposed. The weighting coefficient which could be solved by constructing error sum of squares is applied on F(k) and F(k+1). The solution of iteration k+1 was obtained according to the relation between iteration k+1 and iteration (k). The process above was stopped until the result converges. The proposed algorithm was proved to be correct and effective by using the example of IEEE30 node, and it was applied on the power flow calculation of AC/DC hybrid micro grid under droop control.