Table of Content

25 September 2016, Volume 44 Issue 9

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Computer Science & Technology

A Graph-Based Color Image Segmentation Algorithm

WO Yan JIN Xuan

2016, 44(9):  1-8.  doi:10.3969/j.issn.1000-565X.2016.09.001

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In order to solve the over-segmentation problem in the image segmentation,a graph-based color image segmentation algorithm is proposed.In the algorithm,on the basis of the region-merging method,the over-segmentation regions are obtained by using Mean shift to preprocess an image,and for the over-segmentation regions,a region adjacency graph is constructed.Then,the color,texture and edge contour similarities between adjacency regions are measured to judge if adjacency regions need to be merged,until all the satisfactory regions are merged.Besides,the regions are merged by searching the optimal merging-cost,so as to preserve some global prosperity of the image.Experimental results indicate that the proposed algorithm can completely segment object regions even when the color features between background regions and object regions of an image are similar,and it has a better segmentation performance in comparison with four state-of-the-art segmentation algorithms.

Ontology-Based Adaptive Object Model for Simulated Physical Parameter Management

WU Yuan-hao LUO Pan-feng ZHANG Cheng-wei TIAN Ling YOU Zheng

2016, 44(9):  9-15.  doi:10.3969/j.issn.1000-565X.2016.09.002

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In order to avoid the repeated system development in different domains and support the model redefinition and extension at run time,an ontology-based adaptive object model for simulated physical parameter management is constructed.By abstracting the general high-level data type in simulated physical parameter management,the formal definition and ontology modeling method of the corresponding meta-model are presented,and the modeling method and cases of the corresponding domain model is further presented.Moreover,the domain adaptability,dynamic extendibility,and data evolvability of the proposed model are analyzed.Finally,the proposed model is applied in the physical parameter management system for the flexible media domain in an ATM development company.Thus,the effectiveness of the proposed model is verified.

A Haze Removal Algorithm Combining Fractional Differential,Dark Channel Prior and Retinex

MA Rong-gui WANG Wei-xing LIU Wei ZHANG Yi XU Lian

2016, 44(9):  16-23.  doi:10.3969/j.issn.1000-565X.2016.09.003

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In order to improve the clarity of haze images,this paper proposes a haze removal algorithm combining the fractional differential,the dark channel prior and the Retinex.In the algorithm,a high-texture haze image is processed first through the fractional differential and then through the dark channel prior.Moreover,on the basis of the depth map obtained through the dark channel prior,the Retinex scales are calculated in each part of the processed image.Finally,the image enhancement result is got by performing the Retinex transform of the image after the fractional differential operation.The test results of a number of haze images show that the new algorithm can effectively improve the clarity of haze images with less Retinex halo phenomena,and in comparison with the existing dark channel prior and multi-scale Retinex algorithms,it has a higher processing speed and a better image enhancement effect for the haze images of the high texture and great scene depth difference.

An Overlapping Community Detection Algorithm Based on Addtion of a Clique at Each Step

ZHANG Xing-yi ZHENG Wen WANG Cong-tao DING Zhuan-lian SU Yan-sen

2016, 44(9):  24-31.  doi:10.3969/j.issn.1000-565X.2016.09.004

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The local expansion-based overlapping community detection algorithms start from a single node or a clique,and then repeatedly add a new node to the obtained community,thus obtaining the final community.However,the existing local expansion-based overlapping community detection algorithms always add one node at each step,so the local information of the added nodes has not been fully considered,thus reducing the accuracy of the algorithms.In order to solve this problem,an overlapping community detection algorithm is proposed,which adds a clique at each step.This algorithm starts from a clique,and expands the clique by repeatedly adding a clique of the largest fitness value in the neighborhood.In this way,the links between the added node and the existing community and the links between the added nodes are both taken into account.An empirical evaluation on the synthetic and real datasets demonstrates that the proposed algorithm can detect the overlapping communities in complex networks more accurately than the existing algorithms.

A Sample Optimization Algorithm of Saccade Signals Based on Independent Component Analysis

Lü Zhao LU Yu ZHOU Beng-yan WU Xiao-pei

2016, 44(9):  32-40.  doi:10.3969/j.issn.1000-565X.2016.09.005

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In order to improve the performance of an electrooculogram ( EOG) -based human activity recognition ( HAR) system and increase the correct recognition ratio of multi-class saccade signals,a sample optimization algorithm is proposed on the basis of independent component analysis ( ICA) .In the algorithm,by taking a single saccade data as the object,an automatic selection method of saccade related independent components ( SRICs) is designed according to the independent components ( ICs) -to-electrode mapping mode,and a corresponding ICA spatial filter is established.Then,noisy saccade samples are deleted on the basis of the correct recognition ratio of saccade signals after the linear projection of original EOGs.In the lab environment,the ICA spatial filter is utilized to classify four types of saccade signals by“run-to-run test”and“session-to session test.The results show that,in the two tests,the correct recognition ratios of the data optimized by the proposed algorithm are respectively 99.57% and 98.82%,and they are 0.57% and 0.83% higher than those of original EOG signals,which means that the proposed algorithm can effectively optimize saccade signals and thus improve the correct recognition ratio.

An Error Diffusion Algorithm with Variable Coefficients Based on Texture Structure and Tone Awareness

WANG Xin-bo HU Jian-hua WANG Yun-kuan WU Shao-hong LU Hao

2016, 44(9):  41-46.  doi:10.3969/j.issn.1000-565X.2016.09.006

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The traditional error diffusion algorithm may cause unexpected artifacts to produce and it can't present the details very well.In order to solve these problems,an error diffusion algorithm with variable coefficients is proposed on the basis of texture structure and tone awareness.In the algorithm,first,according to local visual errors of an image,the threshold is modified by performing the noise modulation in smooth regions and by utilizing the texture information in textured regions.Then,by taking into consideration the spectral characteristic of blue noise and the spatial characteristic of the image,the adaptive error diffusion coefficients at each gray level are obtained by using the ant colony algorithm.Experimental results show that the proposed algorithm can output halftone images to reduce the unexpected artifacts and can ensure the details of texture structure,and that it has a better performance in terms of PSNR and MSSIM.

Neural Network-Based Public Opinion Prediction Method for Microblog

HE Yan-xiang LIU Jian-bo SUN Song-tao

2016, 44(9):  47-52.  doi:10.3969/j.issn.1000-565X.2016.09.007

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In view of the characteristics of microblog platform,a public opinion prediction method is proposed on the basis of neural networks.In this method,the post amount in unit time is taken as the quantitative index of event trend.Then,by considering the factors influencing events,the modeling is performed according to sample data,and the neural networks are employed to predict the future trend of the events outside the scope.Simulation results show that the proposed method is fast in terms of the quantization and modeling of the event trend,and it is effective in predicting the outbreak point and the post amount.

Electronics, Communication & Automation Technology

An Improved Three-Dimensional Path Planning Method of Mobile Robot

WU Yu-xiang WANG Chao

2016, 44(9):  53-60.  doi:10.3969/j.issn.1000-565X.2016.09.008

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In a known working environment,the three-dimensional global path planning of mobile robots is investigated in this paper.Firstly,both the updating strategy of global pheromone and the calculation method of pheromone increment in the ant colony algorithm are improved to make the planned path more reasonable.Next,the safety factor is introduced into the path planning and is calculated off-line in advance.Then,a fallback mechanism is designed to clear the pheromone of the point where ants fall into a deadlock,so as to achieve efficient obstacle avoidance of mobile robots in complex three-dimensional environment.Finally,the traditional search mode is improved to make the mobile robot move in the direction which is perpendicular to the main direction.Simulation results show that the above-mentioned path planning method is of a high searching efficiency with a shorter threedimensional path,and it is more practical.

Effects of Active Layer Thickness of Dual-Gate Amorphous InGaZnO Thin Film Transistors on Their Electrical Characteristics

CAI Min-xi YAO Ruo-he

2016, 44(9):  61-66,72.  doi:10.3969/j.issn.1000-565X.2016.09.009

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Dual-gate amorphous InGaZnO thin film transistors ( DG a-IGZO TFTs) have better electrical characteristics than single-gate a-IGZO TFTs.In this paper,on the basis of a model describing the exponential distribution of defect states of a-IGZO/SiO₂ interface,the effects of the active layer thickness of DG a-IGZO TFTs on their electrical characteristics are investigated by taking into consideration the interface defect states.The results show that,as the active layer becomes thinner,the two gates of DG a-IGZO TFTs get coupled more strongly,which causes the conduction channels initially locating at the front and back interfaces of active layer to extend into the bulk of a-IGZO,thus greatly increasing the field effect mobility of DG a-IGZO TFTs.In addition,with the decrease of the active layer thickness,the field effect mobility of DG a-IGZO TFTs gradually becomes immune to the interface defect states,while the subthreshold swing becomes more sensitive to the interface defect states.

Active Bonding Mechanism Between Sn3.5Ag4Ti( Ce,Ga) and SiO₂ Substrate at Low Temperature

CHENG Lan-xian LI Guo-yuan

2016, 44(9):  67-72.  doi:10.3969/j.issn.1000-565X.2016.09.010

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The interfacial microstructure and soldering mechanism of the low-temperature active bonding SiO₂ substrate with Sn3.5Ag4Ti( Ce,Ga) alloy filler were investigated by means of SEM,EDX and TEM,and the mechanism and dynamic process of the active bonding between Sn3.5Ag4Ti( Ce,Ga) and SiO₂ substrate were analyzed on the basis of the active adsorption and reaction thermodynamics theories.Experiment results show that TiSi and TiO₂ phases form along the interface.Both theoretical results and experimental results indicate that the chemical adsorption of Ti on SiO₂ substrate interface may be the main reason for wetting and plays an important role in the initial bonding stage,and that the main bonding mechanism of Sn3.5Ag4Ti( Ce,Ga) and SiO₂ substrate can be described as the interfacial reaction between Ti and SiO₂ and the forming of correspondent reactants.

Modeling and Analysis of CDMA System Based on United Low-Density Graph

WEN Lei LEI Jing WEI Ji-bo WANG Jian-xin

2016, 44(9):  73-80.  doi:10.3969/j.issn.1000-565X.2016.09.011

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The conventional code division multiple access ( CDMA) is of poor performance when user numbers are overloaded.In order to solve this problem,a united low-density graph is constructed.In the graph,variable nodes are taken as the bridge,and chip nodes and parity check nodes are linked through low density edges,thus combining the low-density spreading matrix of CDMA and the low-density parity check matrix of LDPC codes.Then,by using the message passing algorithm,the multiuser detection and the channel decoding are performed in the graph,thus accomplishing the united detection and decoding scheme.Simulation results show that the united low-density graph can effectively resist multiple access interference and channel noise,and the receiver on the basis of the united low-density graph can achieve a better performance than a Turbo receiver,and that,under overloaded conditions,the united low density graph CDMA outperforms the single low-density graph CDMA in terms of bit error rate，average iteration number,message convergence and near-far effect，and even under severely overloaded conditions,the united low density graph CDMA still can achieve a satisfactory performance.

3-D Spatial Domain-Based Forward Link Channel Parameter Estimation in Macro-Cell Mobile Communication

ZHOU Jie YAO Ying-li LUO Hong ZHU Wei-na HISAKAU Kikuchi

2016, 44(9):  81-86.  doi:10.3969/j.issn.1000-565X.2016.09.012

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In view of the uniform distribution of the mobile communication environment with 3D scattering clusters,a statistical channel model for 3D spatial domain is constructed in this paper.In the macro-cell communication environment covered by directional antennas,the constructed model is used to estimate the parameters of the spacetime channel in the multipath fading channel,and the probability density functions ( PDFs) of the angle of arrival ( AOA) and the time of arrival ( TOA) are derived for the forward channel link in the multipath fading channel.In addition,the Doppler shift ( DS) caused by the movement of mobile stations ( MSs) is also derived,and the influences of both the spatial channel parameters and the main lobe width of directional antennas on the constructed model are analyzed.When the scattering objects around MSs are assumed as the Gaussian and exponential density models,the constructed model is more suitable to describe special mobile communication environments.The numerical simulation results show that the channel parameters estimated by using the proposed model are consistent with the theoretical and actual communication environments,which makes up for the limitations of the existing statistical channel models of three-dimensional scattering clusters.

Cooperative Communication System with Directive Antennas and Optimal Relay Selection AF Strategy

WANG Ming-wei LI Li-xin ZHANG Hui-sheng XIE Wen-jiao

2016, 44(9):  87-93.  doi:10.3969/j.issn.1000-565X.2016.09.013

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A multi-relay cooperative communication system adopting directive antennas and optimal relay-selection AF cooperative strategy is proposed,and a corresponding formula of system outage probability is derived theoretically.On the basis of the theoretical analysis result,the relationships between the outage probability and the parameters ( namely,the signal-to-noise ratio,the channel fading coefficient,the antenna power gain,the number of relay nodes and the power allocation coefficient) are analyzed by simulations.The results show that the proposed communication system can meet the requirements of military communication for RF stealth,and under the conditions of low signal-to-noise ratio,deep fading channel and limited relay nodes,it has a smaller outage probability in comparison with the cooperative communication system with omnidirectional antennas and the same strategy,which means that the communication reliability is improved.

Gradient-Based Suppression Method of Vehicle Light Interference in Tunnel Scenes

ZHAO Min SHI Yu-xin SUN Di-hua

2016, 44(9):  94-99.  doi:10.3969/j.issn.1000-565X.2016.09.014

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In tunnel scenes,the interference from vehicle light has a strong impact on the accurate extraction of vehicle targets.However,in the existing methods,there is no solution to this problem.Therefore,a suppression method of vehicle light interference is proposed on the basis of light gradient features,and according to the optical radiation and space structure features,a light intensity model of vehicle light illumination on roads and its vehicle light gradient function are constructed.Furthermore,by utilizing the invariance of gradient directions of vehicle light illumination on roads,the non-vehicle light illumination area is screened and a foreground mask is made.Fi- nally,the foreground mask is overlaid with the moving target foreground,thus suppressing the vehicle light Interfe- rence.Experimental results show that the proposed method can effectively suppress the vehicle light interference,and thus improve the extraction accuracy of vehicle targets.

Automotive Engineering

Investigation into Heating System of Lithium-Ion Battery Pack in Low-Temperature Environment

LUO Yu-tao LANG Chun-yan LUO Bu-er-si

2016, 44(9):  100-106.  doi:10.3969/j.issn.1000-565X.2016.09.015

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The charge and discharge performance of lithium-ion batteries deteriorates sharply at low temperatures.In this paper,a heating system for a battery pack consisting of sixteen 37 Ah lithium-ion batteries is designed,which includes electric heating film,transformer oil,silica aerogel plates,etc.Then,by using the ANSYS software,a finite element model of the heating device of lithium-ion battery pack is constructed,and the heating effect of the heating system on the battery pack is analyzed.Finally,the effectiveness and safety of the heating method are verified by experiments.The results show that ( 1) in different low-temperature environments,the time of pre-heating the battery pack to make its temperature higher than 0 ℃ shows a linear change; ( 2) the pre-heating time is 35min and 12 min respectively at the extremely low-temperature of － 30 ℃ and the common low temperature of － 10℃,which means that the heating effect is significant; ( 3) after pre-heating,the discharge voltage of the battery pack increases and thus the discharge performance of the battery pack is improved; and ( 4) the temperature uniformity of the battery pack can be kept within 3℃ by means of oil circulation or standing.

Control Strategy of Power on and Power off of EV and Fault of Battery Management System

TIAN Sheng PEI Feng LI Shi-cheng

2016, 44(9):  107-115.  doi:10.3969/j.issn.1000-565X.2016.09.016

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In order to effectively implement the energy management strategy of the whole vehicle and achieve safe and optimal battery management system,a battery management system is designed according to the structural characteristics of electric vehicles,and the response principle of control nodes of the whole vehicle during the highvoltage power on and off is analyzed.Then,a control strategy of the normal power on and off as well as of the emergency power off is proposed for the whole vehicle,and the fault level of the proposed battery management system is defined.Moreover,fault threshold tables are designed to realize the control strategy under fault condition.Finally,the Stateflow /Simulink software is adopted to perform the control logic modeling and simulation of power on and off for the whole vehicle as well as of the fault of battery management system,and the proposed control strategy is verified by the actual vehicle tests under static and NEDC conditions.The simulation and experimental results show that dealing with high-voltage power on in insulation error and high-voltage power off in HVIL error accords well with the control logic and dealing with high-voltage power off in insulation error ensures the safety of high-voltage,so that the control logic of power on and power off is more conducive to the energy control of the whole vehicle.

Feedforward + Feedback Control for Hydraulic Assistance Drive System of Heavy Truck

ZENG Xiao-hua JIANG Yuan-de LI Gao-zhi SONG Da-feng HE Hui

2016, 44(9):  116-122,150.  doi:10.3969/j.issn.1000-565X.2016.09.017

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In order to improve the power performance of heavy trucks,a new hydraulic assistance drive system ( HADS) is developed for the traditional heavy trucks,which can make the trucks on the roads of low adhesion coefficients reconfigure the traditional rear-wheel drive into the all-wheel drive.Then,a feedforward + feedback controller for a pump displacement controller in the developed system is designed to improve the transmission efficiency of the trucks.By the feedforward controller,the reference pump displacement is determined according to gears,and by the feedback controller,the final value of pump displacement is dynamically corrected according to the velocity tracking error between front wheels and rear wheels.Co-simulation results on the Matlab /Simulink and AMESim platforms show that,after employing HADS on the typical roads of low adhesion coefficients,the maximum climbing grade and traction of the trucks can be improved respectively by 14.4% 17.2% and 13.4% 15.6%.The real vehicle test results show that HADS works efficiently and smoothly,and the simulation model is accurate.

Coordination Control of Engine Starting and DCT Shifting of Hybrid Electric Vehicles While Driving

LIU Yong-gang CHEN Liang QIN Da-tong LEI Zhen-zhen WU Rui

2016, 44(9):  123-130.  doi:10.3969/j.issn.1000-565X.2016.09.018

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On the basis of the distinctive structure and performance advantages of dual clutch transmission ( DCT) ,a single-motor full hybrid electric system equipped with DCT is proposed and its kinetic model is constructed.Then,the rule-based method is adopted to analyze the scope of working mode and the schedule of economical shift by taking the optimal system efficiency as the objective,and a comprehensive working schedule of mode switching and DCT shifting is formulated for hybrid electric vehicles ( HEV) .In view of the intersection between mode switching points and shifting points in the comprehensive working schedule,the coordination control strategy and method of mode switching and shifting are proposed.Finally,on the Matlab /Simulink platform,the engine starting and upshifting coordination control while driving is analyzed by simulations.The results indicate that the proposed coordination control strategy of engine starting and shifting while driving is effective in improving the performance of the proposed system,specifically,it can avoid the clash between mode switching and shifting with much less mode switching and shifting time,which means that the structure advantage of the proposed system are fully utilized.

Estimation of Road Adhesion Coefficient Based on Work-Energy Principle and Fuzzy Logic Control

LIN Bo-zong LI Zhen-yang HE Lei ZONG Chang-fu

2016, 44(9):  131-136.  doi:10.3969/j.issn.1000-565X.2016.09.019

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In order to avoid the effects of tire parameters on estimation accuracy,the tire models are not introduced in this paper.On this basis,a road adhesion coefficient estimation algorithm combining the work-energy principle and the fuzzy logic control is proposed.First,the utilized adhesion coefficient under current vehicle state is estimated on the basis of the work-energy principle.Then,by using a fuzzy logic controller,the maximum adhesion coefficient of current road is estimated according to both the utilized adhesion coefficient and the slip ratio under the current state.Finally,by employing the Matlab software,a vehicle model of three degrees of freedom is constructed to analyze the proposed algorithm by simulations.The results show that the proposed algorithm can effectively estimate the road adhesion coefficient,and has good real-time and accuracy.

Analysis of Electromagnetic and Shock Wave Mitigation Capability of a Novel Sandwich Plate with Composites

BAI Zhong-hao HE Cheng ZHU Feng

2016, 44(9):  137-143.  doi:10.3969/j.issn.1000-565X.2016.09.020

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In order to develop a novel vehicular armor plate against radar surveillance systems and blast attack harming occupants,by adopting the glass fiber composite,the functionally-graded polyurethane foams filled with multiwalled carbon nanotubes ( MWCNT) and the carbon fiber composite to respectively make the top surface,the core and the back surface,a novel sandwich plate is designed,which can absorb electromagnetic ( EM) waves and attenuate the shock wave transmission.Then,the analytical models of the EM reflection and the shock wave transmission are developed for the novel structure,and the effects of the gradient pattern and thickness of each dielectric layer on the EM reflection coefficient and the shock wave transmission coefficient are investigated.Moreover,the NSGA-Ⅱ algorithm is used to conduct a multi-objective optimization of structure parameters of armor plate.The results show that,after the optimization,the electromagnetic wave reflection coefficient and shock wave transmission coefficient of the novel structure decrease respectively by 94.58% and 4.35%,which means that the EM absorbing ability and shock wave attenuation ability of the novel structure are both excellent.

Particulate Emission Characteristics of Diesel Engine Fueled with Diesel /Ethanol Blends

HOU Xian-jun XU Jing LIU Jin-ping DU Song-ze LI Meng-meng

2016, 44(9):  144-150.  doi:10.3969/j.issn.1000-565X.2016.09.021

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An experiment in a diesel engine fueled with diesel /ethanol blends was conducted,and the particle concentration and particle size distribution of the particulate matter from the diesel engine were investigated by DMS500 analyzer with fast response particulate.Then,the size distribution,mass concentration and geometric mean diameter of the particulate matter obtained under different running conditions of engine with different ethanol ratios were analyzed.The results show that ( 1) the particulate matter from diesel /ethanol blends follows a logarithmic distribution,which has two modes,namely,nucleation mode and accumulation mode; ( 2) with the increase of ethanol ratios,the nucleation mode particle number ( PN) density significantly decreases under a low load,while under medium and high loads,the accumulation mode PN density significantly decreases with an increase of the nucleation mode particle ratio and a decrease of the particle size; ( 3) for the particulate matter from diesel /ethanol blends,the mass concentration is lower than that from diesel,and the particle mass concentrates mostly in the accumulation mode; and ( 4) after the addition of ethanol to diesel,the geometric mean diameter of particulate matter significantly decreases,and it decreases gradually with the increase of ethanol ratios.