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15 September 2019 Volume 32 Issue 9
  
    Preparation of High Performance GaN Nanowire Arrays by Top-down Method
    GUI Qi,ZHU Yuankun,WANG Xianying
    Electronic Science and Technology. 2019, 32(9):  1-5.  doi:10.16180/j.cnki.issn1007-7820.2019.09.001
    Abstract ( 355 )   HTML ( 12 )   PDF (985KB) ( 51 )  
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    In this paper, the top-down etching method is used to fabricate GaN nanowires for solving the problem that the uncontrollable of the size, morphology and orientation of GaN nanowires grown from bottom. ICP dry etching was used on GaN epitaxy with patterned metal Ni as a mask. The etching parameters were systematically studied, and the effects of ICP power, RF power and wet etching on the morphology, Raman and PL spectra of GaN nanowires were also been investigated. It has been found that when the ICP power is 1000 W and the RF power is 100 W, the intensity of Raman and PL spectra of the GaN nanowires are relatively strong, indicating that the nanowires etched under this condition are with less defects. After immersion in KOH for 30 min, the morphology of GaN nanowires was improved. The intensity of Raman and PL spectra was better than that of only with dry etching, which provided a good nanowires for the preparation of the device application.

    Research on Path Planning of Mobile Robot Based on Improved Ant Colony Algorithm
    LIU Xuefang,ZENG Guohui,HUANG Bo,LU Dunke
    Electronic Science and Technology. 2019, 32(9):  5-9.  doi:10.16180/j.cnki.issn1007-7820.2019.09.002
    Abstract ( 563 )   HTML ( 28 )   PDF (884KB) ( 80 )  
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    In order to solve the problem that the traditional Ant Colony (AC) algorithm had a slow convergence speed and was easy to fall into a local optimal solution, an improved AC algorithm was proposed and applied to the path planning problem of mobile robots. This method built the environment using the grid model, and the obstacles were expanded to effectively reduce the possibility of the moving mobile robot colliding with obstacles. By constructing the heuristic function, the length of the ant colony search path was reduced. The pheromone diffusion algorithm was used to improve the global search ability of the algorithm in the initial stage, so as to accelerate the late convergence speed of the algorithm. The simulation results showed that the proposed improved AC algorithm could plan the optimal path. Besides, compared to the traditional method, the proposed improved AC algorithm doubled convergence speed.

    Adaptive Position Switching Based on Correlation Filters for Visual Tracking
    WANG Runling,TENG Shuo
    Electronic Science and Technology. 2019, 32(9):  10-15.  doi:10.16180/j.cnki.issn1007-7820.2019.09.003
    Abstract ( 193 )   HTML ( 8 )   PDF (979KB) ( 17 )  
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    To solve the problem of constrains between the accuracy and speed for convolutional features for visual tracking methods, an algorithm namely adaptive position switching based on correlation filters was proposed. Pool4 and Conv5-3 layers were selected for features extraction. At the same time, effective features were obtained by the average feature energy ratio, which improved the tracking speed. Then it trained correlation filters with different Gaussian distributions of samples. Therefore, the best classifier was selected to predict the position according to the peak-side-lobe ratio, with a promotion in the generalization ability of the tracker. Finally, the sparse model update strategy was adopted to reduce the over-fitting and further speed up the algorithm. This algorithm was tested on OTB100 benchmark dataset. Tracking results demonstrated that the accuracy was 88.8%, 6.1% higher than the hierarchical convolutional features for visual tracking method. The tracking speed was 47.5 frames per second, which was 5 times than the original method, and showed favorable real-time performance.

    Decision Method Based on Intuitionistic Linguistic Evaluation of Condition Maintenance for Power Transforme
    ZHENG Mingliang,WANG Quan,HUANG Xiang
    Electronic Science and Technology. 2019, 32(9):  15-19.  doi:10.16180/j.cnki.issn1007-7820.2019.09.004
    Abstract ( 184 )   HTML ( 3 )   PDF (716KB) ( 23 )  
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    It was important to study the decision method of condition maintenance for power transformer to improve its operation safety and reliability. For the problem of qualitative evaluation in current decision method of condition maintenance for power transformer, an intuitionistic linguistic evaluation method was proposed by combining intuitionistic fuzzy sets and linguistic evaluation theory. Firstly, in order to get more complete decision information, the intuitionistic linguistic numbers was introduced to express the degree of certainty and hesitancy of linguistic evaluation information from experts. On this basis, an optimization model was established to determine the index weight based on concept of intuitionistic linguistic entropy and comprehensive consideration of various factors. Then in the proposed method, the intuitionistic binary linguistic operators was used to integrate and calculate the decision information from expert group to sort the scheme. Finally, an example analysis demonstrated that the proposed method can cover more decision information and reduce the loss of process in conversion from qualitative to quantitative, and makes the decision result being more objective, reasonable and comprehensive.

    The Application of UAV in Emergency Rescue and Disaster Relief
    CHEN Hao,SHEN Jingfeng,ZHAO Cheng
    Electronic Science and Technology. 2019, 32(9):  20-25.  doi:10.16180/j.cnki.issn1007-7820.2019.09.005
    Abstract ( 385 )   HTML ( 21 )   PDF (1142KB) ( 57 )  
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    For the multi-UAV path planning problem in disaster relief, the genetic algorithm was used to encode the cruise matrix of the UAV group to form a chromosome, the number of individuals and the maximum genetic algebra to optimize the cruise trajectory was set, and a drone terminal traffic transfer matrix that assigns the appropriate power to each user was established due to the 0-1 planning and non- Linear programming, minimizing the sum of time for the drone to complete all tasks. Genetic algorithm analysis results: When 3 drones were sent from H and J, it was took at least 11.37 h to complete the life sign search for the seven key areas. At this time, the total distance of the cruise was 3 808 km, and 3 planes were dispatched from H. The communication equipment and sends different content to the 72 ground terminals in the disaster area was carried by the drone. It was took at least 25.81 h to complete all tasks. At this time, the total distance of the cruise was 1 547 km.

    Recognition of Underground Miners’ Rule-Violated Behavior Based on Safety Helmet Detection
    TONG Zeyou,FENG Shimin,HOU Xiaoqing,DING Enjie
    Electronic Science and Technology. 2019, 32(9):  26-31.  doi:10.16180/j.cnki.issn1007-7820.2019.09.006
    Abstract ( 277 )   HTML ( 9 )   PDF (895KB) ( 31 )  
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    In order to solve the problem of the miner's helmet-wearing recognition, this paper proposed a method of detecting the safety helmet based rule-violated activity. It was based on the face recognition and helmet detection. Firstly, detect the human faced in the picture and identify them, and then detect whether the person wears a safety helmet or not with the Convolutional Neural Network approach. This paper compared the depth learning method with the traditional method in different conditions in the experiments.The experimental results showed that the robustness of the depth learning based safety helmet detection method was stronger than the traditional method. The recognition rate of the depth learning method was higher than that of the traditional approach under different conditions. The deep learning method achieved an average recognition rate of 97% and the average running time was less than 1/7 of that of the traditional approach.

    Multi-face Tracking and Optimal Face Extraction
    TIAN Xiong,WU Wei,LIU Xiaoshang,WU Xiu
    Electronic Science and Technology. 2019, 32(9):  32-37.  doi:10.16180/j.cnki.issn1007-7820.2019.09.007
    Abstract ( 233 )   HTML ( 6 )   PDF (972KB) ( 17 )  
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    Aim

    ing at the problem that repeated recognition of the same person in video face recognition system, a multi-face tracking and optimal face extraction method was proposed. Using ViBe modeling to extract the motion area, reducing the data processing area; The Haar feature was combined with the AdaBoost algorithm to detect the face, and the skin color detection was used to determine whether there was a false detection; Tracking faces with CamShift algorithm; Using the Sobel operator to got a clearer face image. Experiments showed that under this method, the face false detection rate was reduced from 2.8% to 0.2%. For 100 frames, the average processing time was reduced from 112 milliseconds per frame to 45.6 milliseconds, and the processing speed was significantly improved.

    Numerical Simulation and Experimental Study of the Magnetostrictive Transducer
    JIANG Yinfang,LIU Bing,LEI Yulan,CHEN Bo,GUO Yongqiang,HU Huajian
    Electronic Science and Technology. 2019, 32(9):  37-41.  doi:10.16180/j.cnki.issn1007-7820.2019.09.008
    Abstract ( 213 )   HTML ( 7 )   PDF (861KB) ( 14 )  
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    To solve the problem that the rectangular Terfenol-D oscillator cannot be coupled with any surface of the pipeline, a new structure is desnd transient response analysis were performed on the oscillator with the new structure, and the length of the oscillator with the new composite igned to combine the U-type base with the Terfenol-D oscillator to make it better coupled with the pipeline. Numerical simulation astructure was confirmed to be 25 mm. The same pipe was tested with a 25 mm new structure transducer and a piezoelectric ceramic transducer. The experimental results show that the flaw echo amplitude value of the magnetostrictive transducer with the new structure is 1.5 times that of the piezoelectric ceramic transducer, further verifying the correctness of new composite structure design.

    Point-selective Geetest CAPTCHA Recognition Based on Faster-RCNN
    ZHOU Wenkai,HAN Fang,KONG Weijian
    Electronic Science and Technology. 2019, 32(9):  42-46.  doi:10.16180/j.cnki.issn1007-7820.2019.09.009
    Abstract ( 389 )   HTML ( 11 )   PDF (797KB) ( 27 )  
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    In view of the problem that traditional methods were difficult to recognize the geetest point-selective CAPTCHA , this paper proposed a recognition method that based on Faster-RCNN object detection model and convolutional neural network. Firstly, it improved the accuracy of text positioning by simplified RPN, then designed convolutional neural network to classify and identify texts,and trained the Tesseract-OCR identification databases to recognize the message texts. Finally, the result of texts recognition which embedded into background picture corresponded to the result of message texts recognition, then it reached the purpose of CAPTCHA recognition. Experimental results showed that the accuracy of this recognition method up to 72.4%.

    Radio Frequency Fingerprinting Identification Based on Carrier Frequency Stability
    WANG Zhengwei,GUO Hongli,YANG Xuezhou
    Electronic Science and Technology. 2019, 32(9):  46-50.  doi:10.16180/j.cnki.issn1007-7820.2019.09.010
    Abstract ( 368 )   HTML ( 3 )   PDF (817KB) ( 25 )  
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    Radio frequency fingerprinting is a technology that uses the uniqueness of the radio frequency characteristics of the radiation source to identify its individual identity, which has broad application prospects for military and civilian applications. Aiming at the problem that the traditional RF fingerprint features were not stable and difficult to implement, a radio frequency fingerprint identification method based on multi-dimensional frequency domain characteristics such as radiation source frequency offset and phase noise was proposed. Taking the ADS-B signal as an example, statistical principles were utilized to quantify frequency offset and phase noise characteristics, and the Bayesian classification method was applied to classify the signals to finally realize the identification of the individual identity. The algorithm was validated by semi-physical generation and real-time ADS-B signal data. The experimental results showed that the method could effectively distinguish the same type of radiation source, and the recognition rate of the four targets in the real environment was 93.5%.

    License Plate Character Recognition Technology Based on Hybrid Neural Network
    ZHANG Changqing,YANG Nan
    Electronic Science and Technology. 2019, 32(9):  51-54.  doi:10.16180/j.cnki.issn1007-7820.2019.09.011
    Abstract ( 223 )   HTML ( 9 )   PDF (716KB) ( 27 )  
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    License plate recognition was an important part of the intelligent transportation system, and the key was the license plate character recognition technology. A single neural network was difficult to identify fuzzy license plate characters, and a hybrid neural network was proposed to realize license plate character recognition technology. The hybrid neural network combined associative memory with BP neural network to discriminate the input characters twice. After training and feature extraction, the detection results were obtained. Experiments with different noises and different angles showed that the hybrid neural network had higher recognition accuracy.

    Attribute-Based Access Control for the Perception Layer of The Internet of Things
    LIU Chen,MA Sijun,NI Xueli
    Electronic Science and Technology. 2019, 32(9):  55-59.  doi:10.16180/j.cnki.issn1007-7820.2019.09.012
    Abstract ( 267 )   HTML ( 10 )   PDF (771KB) ( 29 )  
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    The perception layer of the IOT contained large sum of environmental data and personal information. Therefore, a strict definition of data access was of great importance for information security and privacy protection of the IOT. Based on the traditional access control model, the concept of attribute was introduced and a proposal of attribute-based access control was proposed. In this proposal, the principal access authority was determined according to the attribute of subject, object, the permission and the environment. The attributed-based access control was superior for its characteristics of strong flexibility, relatively simple control and strong expansibility. It was suitable to the dynamic and large-scale environment and was conducive to solving the problems of access control for the perception layer of the IOT.

    Simulation Research on Fault Location of Underground Cable Based on Wavelet Analysis
    TANG Yang,LI Junhao,XIONG Shuangju,XIE Shiyu,WANG Jinfeng
    Electronic Science and Technology. 2019, 32(9):  60-64.  doi:10.16180/j.cnki.issn1007-7820.2019.09.013
    Abstract ( 246 )   HTML ( 7 )   PDF (970KB) ( 30 )  
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    Aiming at the difficulty of pulse signal recognition in power cable traveling wave fault location, the method of wavelet analysis was applied to the identification of traveling wave signals in power cables was proposed. PSCAD/EMTDC software was used to build an accurate simulation model, and the Daubechies wavelet in MATLAB was utilized to perform 5-layer wavelet decomposition on the simulated waveform. The simulation results showed that the wavelet analysis could be used to analyze the fault signal with full frequency range, which significantly improved the fault location accuracy of the cable. In a certain distance range, the relative error could be effectively controlled below 0.5%.

    Imaging Method for Bistatic Forward-Looking High-speed Maneuvering-platform SAR Based on Series Reversion
    ZHANG Aili,MENG Ziqiang
    Electronic Science and Technology. 2019, 32(9):  65-71.  doi:10.16180/j.cnki.issn1007-7820.2019.09.014
    Abstract ( 265 )   HTML ( 7 )   PDF (1356KB) ( 13 )  
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    BFHM-SAR is a new and special imaging mode, which performs 2D imaging during the whole terminal diving period of high speed maneuvering platform. In the BFHM-SAR, the transceiver platform moves along different curve trajectories and has great velocities and accelerations, which leads to the problem of high-order terms under the double root and more serious range cell migration in the double-base distance history. In addition, this configuration has a more serious distance migration problem than monostatic or bistatic SAR. This study firstly corrected the range walk in time domain to reduce the two dimensional coupling, and then derived the two-dimensional frequency spectrum by the method of series reversion based on the accurate approximation of slant range in high order. The remaining rang cell curvature was corrected in range frequency azimuth Doppler domain and the high resolution imaging was completed after the pulse compression in both range and azimuth directions. In addition, focus depth in azimuth direction in this special configuration was analyzed in detail. Finally, the validity and feasibility of the proposed approach were verified with the simulation results.

    Research on Collision Risk Based NUCp of ADS-B
    LIU Shuai,QIN Shanshan,GUO Jinxiang
    Electronic Science and Technology. 2019, 32(9):  72-75.  doi:10.16180/j.cnki.issn1007-7820.2019.09.015
    Abstract ( 249 )   HTML ( 10 )   PDF (722KB) ( 25 )  
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    Automatic Dependent Surveillance Broadcast (ADS-B) technology had the advantages of high monitoring accuracy, fast refresh, low cost and simple maintenance. It was favored by civil aviation air traffic control departments and was often used in route surveillance services. As an important parameter of ADS-B, the horizontal position uncertainty of ADS-B reflected the level accuracy of target positioning. In this paper, the horizontal position uncertainty of DO-260 version was analyzed, and the correctness of position errors of different levels of horizontal accuracy was verified. Based on the probabilistic and statistical characteristics of position error, the collision risks such as target conflict and danger proximity under current ADS-B operating interval were evaluated, which provided a theoretical basis for flight interval assessment under ADS-B control.

    Research on Perception Quantification-based Neural Speech Synthesis Methods
    LIU Qingfeng,JIANG Yuan,HU Yajun,LIU Lijuan
    Electronic Science and Technology. 2019, 32(9):  76-79.  doi:10.16180/j.cnki.issn1007-7820.2019.09.016
    Abstract ( 207 )   HTML ( 8 )   PDF (1338KB) ( 26 )  
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    Current neural network based speech synthesis framework is designed for single speaker, requiring at least a few hours training, and cannot make use of speech data from different speakers, languages, styles. To address this problem, a perception quantification-based neural network speech synthesis method was proposed. In the proposed method, a perception quantification-based model was designed to learn the representations for different attributes of speech. A unified acoustic model was built using the learnt perception quantification representations for different speakers, languages and styles. An adaptation method was introduced to transfer the knowledge from the unified acoustic model to new speakers with limited speech data. The proposed method could effectively control the speaker, language, and style of synthetic speech, achieve cross-language, cross-style speech synthesis, and the adaptation method could reduce the demand for training data to a few minutes. The proposed methods significantly improved the quality and flexibility of speech synthesis systems, and the naturalness of synthesized speech is similar to or better than an average mandarin speaker.

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