Table of Content

31 May 2018, Volume 36 Issue 3

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Communication Engineering

An Autoencoder-Based Data Collection Scheme for Wireless Sensor Networks

LI Guo-rui, TIAN Li, CUI Hao, CHEN Hao-bo

2018, 36(3):  411-419.  doi:10.3969/j.issn.0255-8297.2018.03.001

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Data collection is one of the key operations in wireless sensor networks. In this paper, we propose an energy efcient data collection scheme for wireless sensor networks by using an autoencoder. It includes the model training process and the data collection process. In the model training process, historical dataset is utilized to train the autoencoder with the goal of obtaining a measurement matrix and a reconstruction matrix. In the data collection process, the measurement matrix is utilized to compress the sensed data in a distributed manner and the reconstruction matrix is utilized to reconstruct the surveillant data of the whole sensor network. The experiment results show that the proposed scheme presents higher data compression ratio and higher data reconstruction accuracy as well as faster data reconstruction speed than existed data collection schemes.

Performance of Multi-pair Two-Way Massive MIMO AF Relaying over Rician Fading Channels

SUN Xiao-li, XU Kui, XU You-yun, MA Wen-feng

2018, 36(3):  420-430.  doi:10.3969/j.issn.0255-8297.2018.03.002

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This paper investigates a multi-pair two-way massive MIMO amplify-andforward (AF) half-duplex relay system over Rician fading channels, where multiple pairs of users, each equipped with a single antenna, exchange information within pair through a relay with very large number of antennas. Firstly, the paper gives the zero-forcing reception/zero-forcing transmission (ZFR/ZFT) processing matrix under the conditions of perfect and imperfect channel state information (CSI) at the relay. Then, the asymptotic expressions of the end-to-end signal-to-interference-plus-noise ratio are derived. Finally, the asymptotic spectral efciency (SE) at the general power scaling schemes in the case with infnite number of relay antennas are derived and verifed by the Monte-Carlo simulations.

Reliability of D2D System Related to Distance in Rayleigh Fading Channel

LIU Jin, ZHAO Jun-hui, LIU Yun-yi

2018, 36(3):  431-442.  doi:10.3969/j.issn.0255-8297.2018.03.003

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Under the control of the base station, both sides of the device-to-device (D2D) communication can communicate directly without going through the base station. In order to improve the system capacity, the system reliability and the diversity gain, this paper introduces a relay technology into D2D communication system, and adopts relay strategies including amplify-and-forward mode and decode-and-forward mode. Considering the influence of relay position on the reliability of D2D system, this paper establishes a distance model and derives the formula of the outage probability of the system under different conditions in Rayleigh fading channel. Simulation results show that relay technology can effectively reduce the outage probability in the case of low system channel target rate, that the closer to the midpoint of the D2D communication link the relay node, the lower the outage probability, and that the reliability of the communication relay system is better than that of the non-relayed D2D communication system.

Simulation of Temperature Field Distribution of CO₂ Laser Annealing Ge Core Fiber

ZHAO Zi-wen, MAO Yu-ji-zhe, CHENG Xue-li, CHEN Na, DONG Yan-hua, WANG Ting-yun

2018, 36(3):  443-450.  doi:10.3969/j.issn.0255-8297.2018.03.004

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The temperature feld distribution of Ge core fber in the process of CO₂ laser annealing is simulated by using COMSOL Multiphysics. The influences of laser power and fber moving velocity in axial direction on the temperature feld distribution in the laser heating zone are simulated. Accordingly, the proper laser powers corresponding to different moving velocities of fber are preliminarily obtained. For the Ge core fber with the inner diameter of 80 μm and outer diameter of 300 μm, the proper laser powers corresponding to the axial movement velocities of 4 mm/s, 8 mm/s, 12 mm/s, 16 mm/s and 20 mm/s are 1.5 W, 2.0 W, 2.5 W, 3.5 W, and 4.0 W, respectively. The simulation of the paper provides a theoretical basis for optimizing the performance of the Ge core fber by CO₂ laser annealing.

Anti-interference Method of LED Visible Light Communication and Its Engineering Implementation

SU Yun-xia, WU Ya-ting, ZHANG Xue-fan

2018, 36(3):  451-460.  doi:10.3969/j.issn.0255-8297.2018.03.005

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Light-emitting diode (LED) visible light communication (VLC) is a promising technology due to its unique advantages. However, it suffers from the problem of light interference. This paper proposes anti-interference methods from several aspects aiming at LED VLC’s vulnerability to the interference of stray light and dust. In frequency domain, we propose an anti-interference flter which flters out the outside-band noise. In time domain, we propose phase-lock-demodulation related coherent demodulation method and theoretically deduce the process. In method of signal modulation, we propose a driving method of anti-interference transmission circuit for LED optical communication and illumination. To improve the effectiveness of photo-electric conversion, we propose a sensitive optical receiver circuit scheme. Experimental results indicate that the proposed scheme has good anti-interference ability to stray light. The communication distance exceeds 20 m, which shows the practical application value of our scheme.

Signal and Information Processing

Quality Evaluation Method for the Results of Digital Orthophoto Mosaic

ZHANG Sha-sha, WANG Shu-gen

2018, 36(3):  461-470.  doi:10.3969/j.issn.0255-8297.2018.03.006

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For the quality evaluation of the Digital Orthophoto mosaic, a quantitative evaluation method, which is based on the buffer images and includes both the radiometric consistency and geometric consistency indexes, is presented in this paper. Firstly, the buffer zones are built around the seamline, and the buffer images are obtained from the left and right images corresponding to the seamline. Then based on this, the quality evaluation indexes can be calculated, among them, the radiometric consistency is mainly evaluated by the indexes of the gray contrast coefcient and the Uniform Intensity-Distribution, the geometric consistency is mainly evaluated by using the offset distance of the SURF (speeded-up robust features) feature matching points. Finally, the evaluation results of mosaic quality are obtained. Using 36 urban orthophotos of the Vaihingen area of Germany and 36 mountain orthophotos of the Enshi area of China as an experiment data set, the quality evaluation was carried out for the mosaic results respectively obtained by three business softwares of ArcGIS, OrthoVista and DPGrid, which verifes the effectiveness of the proposed method.

Target Detection from High Resolution Remote Sensing Images Based on Combination of Multi-scale Visual Features

FENG Fa-jie, LI Jun-ping, DING Ya-zhou, ZHU Kun, CUI Wei-hong

2018, 36(3):  471-484.  doi:10.3969/j.issn.0255-8297.2018.03.007

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To utilize the spatial structure and color information of the target in the high resolution remote sensing images, this paper proposes a method of target detection based on multi-scale visual feature combination. Firstly, we use two types of feature descriptor to express the color and spatial structure information of targets, one is the dense spatial pyramid scale-invariant feature transform (SIFT) descriptor in spatial pyramid of the color transformed images, the other is the multi-scale histogram of oriented gradient (HOG) feature combined with the hue, saturability and value (HSV) features. Secondly, the two sets of features are used to train classifer through support vector machine (SVM). For the color transformed dense SIFT spatial pyramid feature descriptor, the input of SVM is constructed by spatial pyramid matching kernel (SPMK). For the combined HOG and HSV feature, the orderly-combined eigenvectors are taken as the input of the SVM classifer. Finally the intersection of the two classifcation results are regarded as the fnal results. For verifcation, we tested the buildings and fsh rafts in aerial images and the yachts in satellite images. Experimental results show that the proposed method can improve the precision of target detection, which can reach to by 90% or better.

Half-Art—A New QR Code Artistic Algorithm Based on Halftone and Qart

YAN Bo-yu, SUN Cheng-jun, FENG Fan, ZHANG Jin, GONG Xiao-li

2018, 36(3):  485-494.  doi:10.3969/j.issn.0255-8297.2018.03.008

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In order to improve the recognition and diversity of quick response (QR) Code, this paper analyzes Halftone algorithm, illustrates its basic idea, advantages and disadvantages, and extends Halfton. In addition, based on some ideas from Halftone and QArt, a new artistic algorithm called Half-Art is put forward. The algorithm is divided into two stages: data modifcation and image processing. The mathematical features of the ReedSolomon codes (RS codes) and binarized layer masking algorithm are used to combine the target image with the QR Code. The algorithm combines the advantages, makes up shortcomings of Halftone and QArt. The optimized QR Code has good readability when spread through electronic channels.

Restricted Boltzmann Machine Algorithm for Image Classifcation and Its Parallel Implementation Based on (2D)² PCA

SONG Hai-feng, CHEN Guang-sheng, JING Wei-peng, YANG Wei-wei

2018, 36(3):  495-503.  doi:10.3969/j.issn.0255-8297.2018.03.009

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In this paper, in order to solve the problem of high time complexity when using restricted Boltzmann machine (RBM) to classify the high resolution image, a RBM algorithm for image classifcation based on two-way 2-dimension principal component analysis ((2D)²PCA) is put forward. The algorithm frstly reduces the dimension in X and Z direction on the image by using (2D)²PCA, secondly extracts the principle components as the input data of the visible layer of RBM network, fnally, builds the RBM network with contrastive divergence algorithm and realizes the image classifcation. The proposed algorithm can solve the drawbacks of the long training time of RBM network, which might lead to the convergence failure of the entire network training state as processing the high resolution image. The parallel experimental results show that the algorithm can achieve both high speed and good parallelism as processing high resolution images. The ratio of acceleration reaches 3.13 as employing a cluster of four parallel machines.

Implementation of Audio and Video Decoding and Synchronous Playback Based on Embedded Systems

ZHANG Sen-yong, GAO Shu-li, CHEN Wei-gang

2018, 36(3):  504-514.  doi:10.3969/j.issn.0255-8297.2018.03.010

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An MPEG-2 TS stream decoding and synchronous playback system is designed and implemented based on ARM embedded system. In order to make full use of the resource of video codec embed in ARM processor, a hardware MFC codec is adopted to decode video data, and the open-source Mad- library (libmad) is used to decode audio data. Furthermore, V4L2 driver interface and ALSA library are adopted to play video and audio frame. Due to the delay of hardware decoding from video frame period, there exists a time difference between audio and video playbacks, causing audio and video unsynchronized. In the designed system, a method that synchronizes the video playback to the audio playback is used to achieve synchronization of audio and video playback. Test results show that the designed system can realize audio and video data decoding and synchronous playback.

Computer Science and Applications

Agricultural Drought Vulnerability Evaluation of Gansu Province

DAI Yong-qiang, WANG Lian-guo, HU Bin

2018, 36(3):  515-523.  doi:10.3969/j.issn.0255-8297.2018.03.011

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Address to the multidimensionality and the uncorrelation of agricultural drought vulner-ability evaluation indicators a new method, projection pursuit based on the improved shufed frog leaping algorithm, is used to evaluate the agricultural drought vulnerability. By combining the chemotaxis operation of bacteria foraging algorithm with the shufed frog leaping algorithm, the method enhances the individual refnement searching ability within solution domain and improves the optimizing accuracy and stability of the projection pursuit model. The proposed method searches for the optimal projection direction and acquires evaluation index weights basing on characteristics of sample data, accordingly, reducing the interference of artifcial empowerment with evaluation results of objectivity. The feasibility and validity of the method are verifed by the analyzing and evaluating the agricultural drought vulnerability data in 14 regions of Gansu province.

HKM Clustering Algorithm Design and Research Based on Hadoop Platform

ZHANG Shu-fen, DONG Yan-yan, Chen Xue-bin

2018, 36(3):  524-534.  doi:10.3969/j.issn.0255-8297.2018.03.012

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In order to solve the problem of traditional K-means clustering algorithm in dealing with large-scale data set, a Hadoop K-means (HKM) clustering algorithm is proposed. Firstly, based on the of sample density, the algorithm excludes the effect of data set point or noise. Secondly the optimization of the initial cluster centers is carried out by selecting K initial centers guided by the thought of maximizing the minimum distance. In the end, the MapReduce programming model of Hadoop cloud computing platform is used to realize the parallelization of the algorithm. Experimental results show that the proposed algorithm not only has high accuracy and stability in clustering results, but also can solve the problems of scalability encountered by traditional clustering algorithms in dealing with large scale data.

Control and System

Research of Control Virtual Instrument on Non-lethal Laser Weapon Transmitting and Attenuating in Rain and Fog

LIU Xia, SHAN Ning, WANG Zhi-jing

2018, 36(3):  535-541.  doi:10.3969/j.issn.0255-8297.2018.03.013

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Non-lethal laser weapon has broad application prospect in the feld of antiterrorism because of its excellent performance. But its performance is subject to atmospheric environment. The attenuation mechanism of laser transmission in rain and fog is studied in the paper. A virtual control system is designed and developed with LabVIEW for the real-time adjustment of light attenuation when non-lethal laser weapons work in rain or fog environment. Experiment results show that the designed system can realize real-time adjustment of laser power in the rain and fog environment with high precision. In addition, the designed system features with friendly interface, easy operation, low cost, expansibility and intelligentization.

Application of Improved Fireworks Algorithm in Optimal Load Distribution of Thermal Power Plant

ZENG De-liang, DENG Zhi-guang, CHEN Yan-qiao

2018, 36(3):  542-552.  doi:10.3969/j.issn.0255-8297.2018.03.014

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In the existing load distribution solutions, there is little consideration on the rapid response of units to network speed and on the small change strategy of units. Moreover, the contradiction between the speed and the economy in the factory-level distribution has not been solved yet. To deal these problems, this paper proposes an algorithm based on the improved freworks algorithm, which changes the load boundary and climbs constraint adaptively, to dynamically achieve rapid response of load changes. At the same time, the algorithm sorts the units according to a predetermined priority order to achieve the minimum unit load changes under the certain constraints when unit load changing occurs. Finally, it introduces a switching mechanism to solve the contradiction among the lowest coal-consumption, quick adjustment and the little unit-change with flexible optimization. The paper presents a specifc algorithm of plant-level real-time online optimization of load distribution and conducts the simulation for an example with four units. The simulation results show the effectiveness of the algorithm.

CE150 Helicopter Model with Input Saturation by Composite Nonlinear Feedback Control

ZHAO Ping, JIANG Yuan

2018, 36(3):  553-566.  doi:10.3969/j.issn.0255-8297.2018.03.015

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This paper introduces the composite nonlinear feedback (CNF) control method to solve the output regulation problems of helicopter model with input saturation. To solve the output regulation problem, an observer and an output feedback CNF control law are constructed. The CNF control law includes a linear control law and a nonlinear control law. A linear state equation of helicopter model and a reference signal is proposed and solved to obtain the feedback gain and the observer gain through the Riccati equation. A linear control part with a small damping ratio and a nonlinear feedback control section for improving transient performance are constructed. In order to study the performance of the controller, we have designed two controllers with or without external disturbances,respectively. Simulation results show that the CNF controller can reduce the pursuit time and pursuit error both for time-variant signals and for time invariant signals, featuring with high transient performance.