Table of Content

25 January 2017, Volume 45 Issue 1

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Electronics, Communication & Automation Technology

Differential Control Strategy and Simulation of Articulated Dump Truck with Six Electric Wheels

JIANG Li-biao QIU Hua-chuan LING Shi-yun HE Jia-shou

2017, 45(1):  1-8.  doi:10.3969/j.issn.1000-565X.2017.01.001

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The existing differential control strategies for the articulated dump truck with six electric wheels can simply achieve differential velocity.Moreover,they ignore yaw control and acceleration slip regulation,which causes the whole truck to show a poor dynamic performance.In order to solve these problems,a differential control strategy on the basis of the hierarchical control of driving force is proposed.Firstly,a dynamic mathematical model of the whole truck containing longitudinal,lateral,yaw and roll degrees of freedom is derived on the basis of Lagrange equation method.Then,the differential control strategy on the basis of the hierarchical control of driving force is designed,which is composed of the decision layer for total driving power and yaw control power,the distribution layer for differential drive and the stability layer for acceleration slip regulation.Finally,active disturbance rejection control algorithm is used to calculate the needed yaw control power to eliminate steering angle deviation,and optimal slip ratio recognition algorithm is used to amend the driving power of each wheel.The offline simulation results show that the proposed strategy can better realize the differential velocity of each wheel under different working conditions on the roads of different adhesion coefficients,and it can ensure better steering performance of the whole truck and better stability of each wheel.

Feedback Control of a Class of Coupled-Map Fuzzy Time-Delay Car-Following System

ZHAI Cong LIU Wei-ming TAN Fei-gang

2017, 45(1):  9-17.  doi:10.3969/j.issn.1000-565X.2017.01.002

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When a driver is sensing headway,there exists a time-varying delay,and the sensitivity of the driver changes with the speed and the headway within a certain range.In order to accurately describe the running state of vehicles,on the basis of coupled-map car-following model,a new coupled-map fuzzy car-following model with timedelays is proposed,and the stability of the new car-following model is investigated.Then,by using Lyapunov function,the sufficient condition of the existence of a fuzzy controller is given.Under this condition,the closed-loop system achieves an asymptotic stability,that is,traffic congestion phenomena can be effectively suppressed.Finally,the fuzzy controller is obtained by solving a linear matrix inequality ( LMI) .Simulation results show that,with the help of the fuzzy controller,the car achieves smaller amplitude of velocity oscillation,faster process of recovering to an equilibrium state,and lower emission of carbon dioxide,which means that this method is effective in suppressing traffic congestion and reducing carbon dioxide emissions.

An Approximate Message Passing Algorithm with Composite Sparse Constraint for CS Reconstruction

XIE Zhong-hua MA Li-hong ZHONG Fu-ping

2017, 45(1):  18-25.  doi:10.3969/j.issn.1000-565X.2017.01.003

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In CS reconstruction,approximate message passing ( AMP) can realize the reconstruction of sparse signals quickly and accurately by performing both wavelet de-noising and residual updating iteratively.However,the sparse constraints of the wavelet coefficients used in AMP are not suitable for non-sparse natural images,especially when the measuring process of CS is disturbed by noises.In order to solve this problem,aCS image reconstruction algorithm is proposed on the basis of composite sparse constraints and an AMP framework.This algorithm takes both the low-rank constraint of similar image patches and the bilateral filter constraint as the joint prior information of natural images to enhance the recovery effect of image textures and edges,thus improving the performance of the algorithm.The results of the reconstruction experiment with no noise in the measuring process of CS show that,the proposed algorithm averagely improves PSNR( Peak Signal to Noise Ratio) by 0.45dB and 6.19dB,respectively in comparison with the AMP algorithm that only uses low-rank constraint and the original AMP algorithm.While in the presence of noise,the corresponding average PSNR gains are respectively 0.25 dB and 4.60 dB.In conclusion,the proposed algorithm can achieve a better visual quality whether it is noiseless or not.

Detection of Time Domain Forgery of H.265 /HEVC Video

WANG Yu-fei LIU Bei-bei HU Yong-jian ZHU Mei-neng

2017, 45(1):  26-34.  doi:10.3969/j.issn.1000-565X.2017.01.004

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In order to solve such time domain forgery problems as the deleting,duplication and insertion of frames in H.265 /HEVC compressed videos,according to new features of H.265 /HEVC coding standard,a time domain forgery detection algorithm on the basis of video compression features is proposed.In the algorithm,with the parameters in the compressed domain of the videos,the position of forgery can be detected without decoding the videos completely.Experimental results show that the proposed algorithm shows good performance in detecting varying degrees of deleting,duplication and insertion of frames as well as different bitrates of forgery videos,and it can also shorten detection time effectively.

An Image Fusion Algorithm Based on Threshold-Improved Contourlet Transform

WU Peng LI Wen-lin QI De-yu SONG Wen-long

2017, 45(1):  35-41,52.  doi:10.3969/j.issn.1000-565X.2017.01.005

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In order to obtain better fusion images,an improved algorithm on the basis of structural similarity ( SSIM) threshold is proposed to determine fusion rules adaptively.In the algorithm,for low frequency sub-bands,a weighting summation fusion algorithm on the basis of correlation coefficient and deviation from mean is adopted to preserve more general information.For high frequency sub-bands,the SSIM of each region of the image to be fused is calculated first and then the corresponding average value is taken as the threshold.Afterwards,a high frequency subband fusion algorithm is selected adaptively according to the relationship between the SSIM of each region and the threshold,so as to retain more detail information.Experimental results show that the improved image fusion algorithm helps achieve the fused images of richer detail,sharper edge and better objective evaluation index of quality.

Multi-Stage Operational Amplifier for Broadband Δ-Σ ADC

XU Ken CAI Min HE Xiao-yong

2017, 45(1):  42-47.  doi:10.3969/j.issn.1000-565X.2017.01.006

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In order to improve the in-band gain and bandwidth of operational amplifiers,a four-stage operational amplifier of the broadband Δ-Σ ADC used in long-term evolution receivers is proposed.In the operational amplifier,a hybrid frequency compensation scheme combining feedforward Gm-C and Miller technique is adopted to ensure the stability.Then,a high-performance four-stage operational amplifier is designed in 0.13 μm 1P6M CMOS technology,and it is applied to the broadband Δ-Σ ADC.Test results show that ( 1) with a power supply of 1.5V,the operational amplifier achieves a unity gain bandwidth of 442MHz,a DC gain of 72.8dB and a slew rate of 101V/μs; ( 2) with the same bandwidth and power dissipation,the in-band ( 0 ～ 10MHz) gain of the proposed amplifier is 6 dB more than that of the traditional two-stage operational amplifier; and ( 3) in a signal bandwidth of 10MHz,the broadband Δ-Σ ADC adopting the proposed amplifier achieves a SNR of 68 dB and a SFDR of 78 dB.

Research on Thermal Hysteresis of Silicon-Based Semiconductor

SUN Zhi-gang HE Xiong XIE Qing-xing LI Yue-chou PANG Yu-yu

2017, 45(1):  48-52.  doi:10.3969/j.issn.1000-565X.2017.01.007

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In this paper,the electrical transport properties ( V-I characteristics) of Ag /SiO2 /p-Si ∶ B /SiO2 /Ag device at different temperatures are investigated by means of four-wire method,finding that an obvious thermal hysteresis phenomenon occurs in V-I curves at low temperatures.In order to eliminate the experimental errors caused by the thermal hysteresis,two methods of prolonging the interval between two consecutive measurements and improving the heat conduction ability of system are proposed,and the first method is used to remove the effects of the thermal hysteresis on the electrical transport properties of the device.The results show that when the electrical properties and magnetoresistance effects of semiconductor-based materials are investigated,the thermal hysteresis phenomenon should be treated carefully,otherwise it may lead to erroneous results.

Multiple-Objects Nulling Antenna with Directional Constraint

ZENG Hao ZHOU Jian-wen WANG Qiu-shi WANG Hong-liang HE Hai-dan

2017, 45(1):  53-58.  doi:10.3969/j.issn.1000-565X.2017.01.008

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In satellite navigation receivers,traditional nulling antennas cannot form the main lobe of satellite signal points.In order to form a plurality of main lobes of an antenna corresponding to different satellite signals and thus to improve array gains,an orientation constraint condition is introduced into this paper,and direct matrix inversion is adopted to solve the optimal weight vectors of each satellite signal.Moreover,a beamforming is completed.Then,the computation amount of the proposed algorithm is discussed,and an analytical expression of the array gains is proposed.It is found that this algorithm not only suppresses the external disturbance but also overcomes the mutual interference between satellite signals,and it causes the main lobes of each satellite signal to form,thus improving output SNR.In addition,the effectiveness of the proposed algorithm is demonstrated by the simulation results of pattern and output SINR.

Design of Chipless Tag Based on Rectangular Slot Ring

MA Zhong-hua YANG Jian-hong CHEN Peng

2017, 45(1):  59-65,73.  doi:10.3969/j.issn.1000-565X.2017.01.009

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In order to reduce the cost of conventional tags and increase their coding capacity without increasing their area,a kind of chipless tag composed of embedded multi-rectangular slot rings is proposed,whose dimension is decreased obviously by embedding.Then,the chipless tag of a twelve-bit code capacity is fabricated on a 35mm× 35mm F4BM-1/2.Coding is realized on the basis of the presence or absence of the rectangular slot ring.The presence is indicated as logical“1”and the absence is indicated as logical“0".Finally,the reading distance of the proposed chipless tag is measured by using a network analyzer in a microwaved anechoic chamber and correct data signals can be received at a distance of 50 cm from transmitting and receiving antennas.The simulation results on the proposed chipless tag of a twelve-bit coding capacity accord well with the examination ones.

Computer Science & Technology

A Hierarchical Dijkstra Algorithm for Solving Shortest Path from Constrained Nodes

KANG Wen-xiong XU Yao-zhao

2017, 45(1):  66-73.  doi:10.3969/j.issn.1000-565X.2017.01.010

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In order to obtain the shortest path from constrained nodes,a hierarchical Dijkstra algorithm is proposed on the basis of backtracking,which is able to find the global shortest path or the second shortest path by searching the local optimal solution within hierarchical structures.Moreover,this algorithm takes full advantage of the hierarchical structures in saving search progress to realize such operations as the saving and backtracking of the search progress during the searching of the shortest path.Experimental results show that the proposed algorithm increases space complexity slightly,but it can reduce the calls of Dijkstra algorithm effectively,and that,as compared with depth-first search algorithm and geometric algebra algorithm,the proposed algorithm may not always find the optimal solution in theory,but it works faster and can still find the sub-optimal solution more quickly even when data volume is large.

Analysis of Vertex-Degree Sequence Length of Complex Networks

XIONG Yun-yan XIAO Wen-jun MAO Yi-jun LAI Zheng-wen HAN Dong LI Mei-sheng

2017, 45(1):  74-79.  doi:10.3969/j.issn.1000-565X.2017.01.011

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In this paper,a conclusion that the length of vertex-degree sequences is of the order log2N ( N is the number of network nodes) in the complex networks exhibiting a Poisson vertex-degree distribution,is theoretically proved.Then,by the simulation experiments on the length of the vertex-degree sequences in random networks,small world networks and scale-free networks,the conclusion is also proved to be correct.Finally,this conclusion is also confirmed in real complex networks by computing the length of the vertex-degree sequences.

A Two-Stage Resource Scheduling Method for Workflow Cloud Computing System

WANG Yan WANG Jin-kuan HAN Ying-hua

2017, 45(1):  80-87,111.  doi:10.3969/j.issn.1000-565X.2017.01.012

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In order to improve the resource utilization of cloud computing systems and optimize the system performance,by taking into account the users' QoS demand,a workflow cloud computing system is established by integrating cloud computing with workflow,and a two-stage resource scheduling model is constructed for the cloud computing workflow system.In the first stage,by considering the time and cost constraints of QoS,the dependencies among the tasks in the workflow,and the processing of the intermediate data from each task,a modified particle swarm optimization algorithm ( MPSO) is proposed,and the Pareto is used to obtain an optimal solution so as to improve scheduling efficiency.In the second stage,by considering the resource allocation on hosts,a scheduling strategy with load-aware is proposed to perform resource scheduling according to system loads,so as to improve the resource utilization of the system.Experimental results show that,in the resource scheduling process of the workflow cloud computing system,the modified MPSO algorithm is superior to the earliest heterogeneous finish-time algorithm and single-objective optimization genetic algorithm in terms of execution speed,resource utilization and users' satisfaction with QoS,and that,the proposed scheduling strategy with load-aware can schedule more efficiently according to the system loads,and the task execution efficiency and the resource utilizationare are thus improved.

A Self-Optimal Relevance Vector Machine with Multiple-Attribute Gaussian Kernel Functions

XU Yu-ge LIU Li LUO Fei

2017, 45(1):  88-94.  doi:10.3969/j.issn.1000-565X.2017.01.013

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In relevance vector machine prediction models,the selection of kernel functions and the values of kernel parameters have great influence on the prediction performance of the models.Aiming at this issue,a novel relevance vector machine prediction model is constructed on the basis of multiple-attribute Gaussian kernel functions,and a self-optimal kernel parameter-learning method is proposed to optimize the kernel parameters.Then,the constructed model is used to predict a two-dimensional standard function as well as the effluent quality of a wastewater treatment system.Finally,this model is compared with several models using different kernel functions and several models using different parameter optimization methods by simulation experiments.The results indicate that the proposed model is less sensitive to lower dimension data and has better output accuracy and sparsity in dealing with higher dimension data,and that it shows a satisfying performance in predicting the effluent quality of wastewater.

Falling Detection and Control of Humanoid Robots Based on Multi-Sensor Information Fusion

BI Sheng LIU Hao-xi MIN Hua-qing DONG Min HUANG Xin-long

2017, 45(1):  95-101.  doi:10.3969/j.issn.1000-565X.2017.01.014

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When humanoid robots are walking,it is essential to detect in time whether the robots are going to fall,so as to prevent the robots from the falling or reduce the damage from the falling with the help of the corresponding protection actions.In this paper,a multi-sensor information fusion model in the stage of walking is constructed by using attitude sensors ( including an acceleration sensor and a gyroscope) and force sensor resistors ( FSR) .Then,a comprehensive judgment method of the falling detection of a humanoid robot is proposed by adopting fuzzy logic decision method,and the corresponding controllers are designed to detect whether the robot is going to fall.If the falling is unavoidable,the corresponding protection actions will be adopted.Otherwise,if the falling can be avoided,it will be prevented by controlling hip joints.The experimental results of SCUT-I humanoid robot show that the proposed method can detect the moment at which the robot is going to fall,and then prevent the falling by using the stability controller or reduce the damage to the robot by using the falling controller to bring about the corresponding protection actions.

MapReduce Job Performance Tuning by Optimizing Memory Configurations

LUO Yong-gang CHEN Xing-shu YANG Lu

2017, 45(1):  102-111.  doi:10.3969/j.issn.1000-565X.2017.01.015

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MapReduce job performance depends heavily on memory configurations.In order to overcome the difficulty in predicting the memory requirement of MapReduce jobs,on the basis of the fact that Java Virtual Machine ( JVM) divides the heap space managed by JVM Garbage Collector into young and old generations,a generational memory prediction method is proposed.In the method,first,a regression model to resolve average garbage collection time for a given young generation size is constructed.Then,the problem of looking for the rational size of young generation is converted into a constrained nonlinear optimization problem,and a fixed-size search algorithm is designed to solve the optimization problem.Moreover,memory models of the Map and Reduce tasks of MapReduce jobs are constructed to solve the memory requirement of optimal performance,thus obtaining reasonable old generation memory size of the Map and Reduce tasks.Finally,a k-means clustering algorithm is used to predict the value of parameter PretenureSizeThreshold,and JVM configurations are tuned to reduce garbage collection pause time.Experimental results show that the proposed method can accurately predict the memory requirements of the Map and Reduce tasks of MapReduce jobs,and it can significantly improve job performance.

Improved Log Data-Merging Method for Process Mining

XU Yang LIN Qi LI Dong

2017, 45(1):  112-117.  doi:10.3969/j.issn.1000-565X.2017.01.016

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The existing process mining techniques and tools are on the basis of a single log file.In actual business process environment,however,a business process may be supported by different computer systems,so that actual process data will be recorded into multiple log files.Therefore,it is necessary to merge the multiple recorded data into one log file for further global process mining and analysis.In this paper,an automatic method is proposed to merge event logs by combining an artificial immune algorithm and simulated annealing.In the method,on the basis of the characteristics of the process logs of multiple IT systems,two operators,namely,the occurrence frequency of activity sequences and the time overlap area between mergeable cases,are taken into account in an affinity function,so as to improve the accuracy of matching cases and the practicality of the proposed method.Moreover,the simulated annealing selection is introduced into the evolution of populations so as to solve the problems of the premature and continuous degradation of artificial immune algorithm,and the immunological memory is also introduced to preserve the diversity of populations and avoid their local convergence.Experiment results show that the proposed method achieves a merging success rate of more than 90%,and it can ensure that process mining results are correct,and that,as compared with the traditional log data-merging method on the basis of artificial immunity,the proposed method speeds up convergence significantly and increases merging efficiency.

Mechanical Engineering

Experimental Investigation into Leaf-Vein-Like Fractal Structure Applied to Evaporation of Vapor Chamber

LIU Wang-yu WANG Li LUO Yuan-qiang

2017, 45(1):  118-122,128.  doi:10.3969/j.issn.1000-565X.2017.01.017

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Due to the fact that the transpiration of plant leaves takes away a large amount of heat,a new leaf-veinlike fractal structure is designed to optimize the thermal structure of vapor chambers,and the heat transfer effect of a leaf-vein-like fractal structure wick in the evaporation of vapor chambers is investigated.Then,by preparing a vapor chamber through chemical etching to perform a thermal experiment,the changes of the temperature difference between the bottom surface of the evaporation and the steam in the vapor chamber are discussed,and the thermal resistance of each part is calculated.Moreover,the thermal characteristics of the wick at the fractal angles of 30°,40°,50° and 60° are compared.The results indicate that the structures of the fractal angles of 40° and 50° have almost the same thermal performance,and the performance is better than those at the fractal angles of 30° and 60°,which means that smaller thermal resistance brings about better heat transfer and flow behaviors.

Analysis of Heat Transfer Channel Surface Characteristic of Micro Heat Exchanger Based on Young's Theory

ZHOU Jian-yang LUO Xiao-ping FENG Zhen-fei DENG Cong WU Di

2017, 45(1):  123-128.  doi:10.3969/j.issn.1000-565X.2017.01.018

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The surface characteristic of the heat transfer channel of micro heat exchangers has a significant effect on the flow boiling performance of fluid.Solid surface energy is often used to describe the surface characteristics of the heat transfer channel,which can provide a theoretical basis for the research of the flow boiling performance of the fluid in micro-channels.In the investigation,the contact angles of deionized water,ethylene glycol and formamide with the left,right and bottom surfaces of the heat transfer channel were measured respectively,and the solid surface energy of the heat transfer channel was calculated on the basis of Young's theory.Then,the forming mechanism of the contact angle difference between the inside and outside surfaces of the micro-channels was analyzed through the Wenzel model of droplet.The results show that the solid surface energy of the left,right and bottom surfaces of the heat transfer channel are respectively 5.2,5.6 and 8.2MJ /m²,and the surface roughness difference causes the inside surface features to be different.

Investigation into Vibration of Metal Rubber Compound Gear Pair Based on Deformation Coordination Design

2017, 45(1):  129-136,144.  doi:10.3969/j.issn.1000-565X.2017.01.019

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In order to solve the return difference problem of traditional gear pairs,the factors influencing the errors in the processes of design,manufacture and installation are quantitatively calculated.Then,by taking into account the influences of tooth thickness deviation,radial pulsation,center distance deviation and temperature on gear deformation,a design method of the metal rubber compound gear pair with automatic deformation compensation is proposed.Moreover,on the basis of ABAQUS finite element analysis,the influences of high and low temperatures on the gear deformation are calculated,and the gear deformations at the high and low temperatures as well as the preloading of theoretical center distance are obtained.Finally,the vibration responses of the metal and compound gear pairs under different preloading are tested.The results show that ( 1) with the increase of the preloading,the vibration acceleration decreases first and then increases; ( 2) the preloading has a great influence on the metal gear pair but a little influence on the compound gear pair,and with the increase of the preloading,the improvement effect of the compound gear pair tends to become more obvious than that of the metal gear pair; and ( 3) the optimal preloading obtained by tests accords well with the calculated result,which verifies the correctness of simulation analysis.

Experimental Investigation into Surface Integrity of Titanium TC4 after Low-Plasticity Burnishing

YANG Dong LIU Zhan-qiang HE Meng PANG Ji-you YE Hong-tao

2017, 45(1):  137-144.  doi:10.3969/j.issn.1000-565X.2017.01.020

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Through single factor test method,the surface topography,micro-hardness distribution and residual stress of titanium TC4 after a low-plasticity burnishing are obtained by using an optical profiler,a micro-hardness tester and a residual stress test instrument,and the surface integrity of the burnished titanium TC4 is evaluated by using the standard data of the topography,roughness,micro-hardness and residual stress of surface.Then,the effects of low-plasticity burnishing parameters ( including burnishing speed,feed speed,hydraulic oil pressure and burnishing passes) on the surface integrity are analyzed comparatively.The results show that ( 1) the hydraulic oil pressure has the most significant effect on the topography,roughness,micro-hardness and residual stress of the burnished surface; ( 2) the surface roughness increases with the burnishing speed,and both the micro-hardness and the residual stress increase with the burnishing passes; and ( 3) higher hydraulic oil pressure and more burnishing passes help achieve a higher surface integrity in the low-plasticity burnishing of titanium TC4.