Table of Content

25 May 2014, Volume 42 Issue 5

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Electronics, Communication & Automation Technology

Numerical Investigation into Flow Field Distribution in High- Power LED Phosphor Coating Process

Guo Qi- wei Hu Yue- ming Li Zhi- fu

2014, 42(5):  1-8.  doi:10.3969/j.issn.1000-565X.2014.05.001

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In this paper,the transportation and atomization of phosphor glue flowing in high- power LED (LightEmitting Diode) phosphor coating process were investigated via CFD (Computational Fluid Dynamics) and numericalsimulations,and the 3D flow field models as well as the mathematical models of phosphor were established to de-scribe the velocity distribution of phosphor glue's flow field between two different spraying guns.Moreover,sprayingexperiments were carried out,and the consistency of simulated results with experimental ones was proved.It isfound that numerical simulation helps accurately predict the phosphor droplets trajectories and the velocity distribu-tion in LED phosphor coating process without establishing any models of atomization process; and that,within thesame spray distance,small phosphor droplet with high velocity may result in short acceleration and deceleration dis-tance.

CSI Quantization and Analysis for Wireless Coordinated Multi- Point System Under Non- Ideal Backhaul Constraint

Zhou Fa- sheng Du Ming- hui Zhan Qi- cong Liang Ya- ling

2014, 42(5):  9-15.  doi:10.3969/j.issn.1000-565X.2014.05.002

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Coordinated multi- point (CoMP) system has been applied to the 4th generation wireless communicationnetwork LTE- A and beyond networks to accommodate ever- growing need for system capacity and diversity.It is par-ticularly suitable for cell- edges.However,there exists bandwidth limit and transmission delay in the non- idealbackhauls of LTE- A CoMP system,which results in imperfect CSI (Channel State Information) feedback from userequipment to base stations and further causes the degradation of CoMP performance.In order to solve this problem,a CSI quantization method on the basis of Grassmann manifold theory is proposed.With this method,an optimalcode book can be obtained to reduce the CSI feedback overhead.Both mathematical analysis and simulation showthat the proposed method helps improve the CoMP performance under non- ideal backhaul constraint.

Channel Estimation- Assisted Demapping Algorithm of High- Order QAM within Shrunk Search Range

Xu Juan Yao Ｒu- gui Nan Hua- ni Gao Fan- qi

2014, 42(5):  16-22.  doi:10.3969/j.issn.1000-565X.2014.05.003

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QAM (Quadrature Amplitude Modulation) is broadly used in various communication systems thanks toits high power efficiency and bandwidth utilization.High- order QAM,because of its wide search range,may resultin high demapping complexity.In order to solve this problem,a novel concept of soft- decision contribution factor isintroduced to evaluate the contribution of reference constellation to the demapping,and a demapping algorithm ofhigh- order QAM within shrunk search range is proposed.Then,some boundary conditions of the algorithm are dis-cussed,and an adaptive selection scheme of search range is finally presented with the assistance of channel estima-tion.Simulated results indicate that (1) the proposed algorithm downsizes the search range without any sacrifice of BER performance; (2) 4096- QAM and 1024- QAM respectively shrink their search range to 12.7% and 19.7% ofthat of the whole constellation; and (3) as the proposed algorithm makes good tradeoff between performance anddemapping complexity.it has a good prospect of engineering application.

Ray Tracing Algorithm Based on Boundary Linear Traveltime Interpolation

Liu Ling- jun Xie Zhong- hua Yang Cui

2014, 42(5):  23-28,35.  doi:10.3969/j.issn.1000-565X.2014.05.004

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In the traditional ray tracing algorithm on the basis of linear traveltime interpolation (LTI),rays trans-mitting through multiple grids may cause error accumulation due to the linear assumption.When the algorithm isapplied to the computerized tomography for industrial flaw detection,the materials to be detected often become acollection of the background and a small amount of defect areas.In order to reduce the accumulative error in thisapplication,a new ray tracing algorithm on the basis of boundary LTI is proposed.In this algorithm,nodes are in-serted on the boundary of different areas to determine rays' refractional angle and to further reduce the accumulativeerror,and the multidirectional cyclic scanning is used for reference to guarantee the ray path when rays transmit ina reverse direction.Simulated results show that the proposed algorithm is superior to the traditional LTI algorithmand the cross- scanning LTI algorithm due to its high traveltime computing accuracy and ray path- tracing accuracy.

Selection Algorithm of Heterogeneous Networks Based on Non- Cooperative Game Theory

Lang Gai- ping Xu Yu- bin Ma Lin

2014, 42(5):  29-35.  doi:10.3969/j.issn.1000-565X.2014.05.005

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In next generation heterogeneous wireless networks,vertical handoff plays an important role in guaran-teeing system performance,and the network selection before vertical handoff execution is a key problem.As theexisting algorithms cannot make users and networks satisfied simultaneously and possess high call blocking rate andcall drop rate,a non- cooperative game theory- based selection algorithm of heterogeneous networks is proposed,which obtains the best network selection scheme by taking into account user preferences,business prices and accesscosts.This algorithm implements network selection from a new perspective,and allocates users' requests throughthe game among member networks.Simulated results show that the proposed algorithm helps not only obtain lowerblo- cking rate and call drop rate but also achieve load balancing,so that it can fully utilize network resources toserve more users.

Phase Retrieval Based on PhaseCut

Zhang Fen Zhang Quan- bing Zhang Cheng Shen Chuan Wei Sui

2014, 42(5):  36-40.  doi:10.3969/j.issn.1000-565X.2014.05.006

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PhaseLift is a new phase retrieval method that converts phase retrieval problems with nonlinear con-straints into semidefinite programming problems.Phase retrieval problems are translated into Maxcut- like semidefi-nite programming problems (namely PhaseCut) by accurately separating amplitude and phase variables combinedwith the method of PhaseLift.As the computational complexity of PhaseCut increases quickly with the problem size,a PURE- RBR- M algorithm suitable for MaxCut problems is employed to solve PhaseCut.Simulated results show thatPURE- RBR- M algorithm achieves phase retrieval successfully and possesses strong robustness to noise measure-ment; and that it is superior to the interior point algorithm and the greedy algorithm because it runs faster and leadsto a quicker signal reconstruction.

Environmental Science & Technology

Macerated Extraction of Main Chemical Components from Abandoned Tobacco Stems and Leave Powders

Gao Wen- hua Chen Ke- fu Ye Dai- qi Yang Ren- dang Yang Fei

2014, 42(5):  41-47.  doi:10.3969/j.issn.1000-565X.2014.05.007

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Macerated extraction is an important step of producing reconstituted tobacco sheets by paper- makingtechnology,and the extracting solution is also a major ingredient for making high- quality reconstituted tobacco coa-tings.In this paper,the main chemical components in abandoned tobacco stems and leave powders were extractedby combining an orthogonal test with single- factor experiments,with water as the solvent.Then,the effects ofmaceration time,maceration temperature and solid/liquid ratio on extraction rate were investigated,and the optimalmacerated extraction conditions for abandoned tobacco stems and leave powder were determined.The results showthat,under the optimal conditions for abandoned tobacco stems,i.e.,a maceration time of 100 min,a macerationtemperature of 60℃ and a solid/liquid ratio of 1∶ 7,the dissolution rates of water- soluble sugars and total alkaloidare 50.60% and 52.46%,respectively; and that the dissolution rates respectively reaches 73.06% and 64.57%under the optimal conditions for abandoned tobacco leave powders,that is,a maceration time of 60 min,a macera-tion temperature of 70℃ and a solid/liquid ratio of 1∶ 10.

Characteristics of Disinfection By- Products Formation from Algae Organic Matters in the Process of Chlorination

Gao Nai- yun Zhu Ming- qiu Zhou shi- qing Li Lei Rong Wen- lei Zhou Sheng- dong Lu Na- xin

2014, 42(5):  48-53.  doi:10.3969/j.issn.1000-565X.2014.05.008

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Six kinds of nitrogen- enriched intracellular and extracellular algae organic matters of Microcystic aerugi-nosa with different characteristics were obtained via the fractionation electrodialysis of hydrophilic and hydrophobiccomponents,with the mass concentrations of dissolved organic nitrogen (DON) ranging from 0.57 to 1.69 mg/L.Then,the 3D fluorescence spectrography was adopted to analyze the composition of hydrophilic and hydrophobiccomponents,finding that the former was mainly composed of humus- like substances and the latter mainly composedof protein.Afterwards,the formation characteristics of carbonaceous (nitrogenous) disinfection byproducts fromdifferent organic matters were analyzed and compared after a 3- day chlorination.The results show that (1) hydro-phobic intracellular and extracellular organic matters are of maximum trihalide methane formation potential,espe-cially for chloroform; (2) there is a significant correlation between haloketone formation potential and intracellularand extracellular organic matters; (3) the hydrophilic component in intracellular organic matters is of the greatestnitrogenous disinfection by- products formation potential (DBPFP); (4) the disinfection by- products formation po-tential of each component is not only determined by the value of DOC/DON (namely the mass concentration ratio ofdissolved organic carbon to DON) but also by the characteristics of DON; (5) the DBPFP of extracellular organicmatters is positively correlated with the content of aromatic organic materials,while that of intracellular organic mat-ters is mainly influenced by the properties of aromatic organic materials; and (6) the disinfection by- products pro-duced by extracellular organic matters are in a content order of hydrophobic by- products ＞ hydrophilic by- products＞ transphilic by- products,while those produced by intracellular matters are indicative of the following order: hy-drophilic by- products ＞ hydrophobic by- products ＞ transphilic by- products.

Investigation into a New Integrated Water Purification Process of Half Coagulation/Ozonation/Ceramic Membrane Filtration

Fan Xiao- jiang Lei Ying Zhang Xi- hui Chao Meng Hiroshi Noguchi

2014, 42(5):  54-59.  doi:10.3969/j.issn.1000-565X.2014.05.009

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In order to control the membrane fouling caused by the half coagulation/ozonation/ceramic membranefiltration of micro- polluted water and investigate the removal capability of this process for pollutants,a bench- scaletest was carried out,and the effects of coagulant dosage and ozone dosage on trans- membrane pressure and effluentquality were explored. The results show that (1) membrane fouling can be alleviated significantly by half coagula-tion and ozonation,for instance,the trans- membrane pressure decreases rapidly from the original －0.074 MPa to－0.021 MPa at a PAC (Polyaluminum Chloride) dosage of 12.5 mg/L and decreases from － 0.068 MPa to－0.049MPa as the O₃ dosage increases from 0mg/L to 2mg/L; (2) the organic matter in water can be removedefficiently by the integrated process; for instance,the molecular mass distribution range of the organic matter chan-ges from less than 5 ku to less than 3 ku,which means a transformation of part of organic matter from large molecu-lar mass to a smaller one; (3) the integrated process helps achieve 60.00% and 68.00% of COD_Mn and UV₂₅₄ re-movals as well as 57.59% and 48.39% of THMFP and HAAFP removals,respectively; (4) after the integratedprocess, the effluent turbidity decreases to less than 0.05NTU,the number of particles larger than 2μm decreasesto less than or equal to 10CNT/mL,and the bacteria and coliform groups in water are entirely removed.Thus,themicrobial safety of the effluent is successfully guaranteed.

Traffic & Transportation Engineering

Analysis and Evaluation of Adaptability to Velocity Band for Green Wave Coordination Control Scheme

Lu Kai Wu Huan Yang Xing Xu Jian- min

2014, 42(5):  60-66,83.  doi:10.3969/j.issn.1000-565X.2014.05.010

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Aiming at the uncertainty of actual running speed of vehicles,the influence of speed variation on actualresults of green wave coordination control scheme for traffic signals is analyzed.Then,by determining the velocityband of normal moving vehicles and by setting the average design speed for green wave coordination control,alter-native schemes of arterial green wave coordination control are generated.Finally,on the basis of green wave band-width expectation,the alternative schemes are evaluated and optimized under corresponding velocity distributions.The results of example analysis and simulation show that the proposed method takes into consideration the velocityband and distribution in different arterial directions and helps choose the best green wave coordination controlscheme from many alternative schemes according to sampled data and probability distribution of actual runningspeed.Thus,it is efficient in realizing the quantitative risk evaluation of coordination control schemes for traffic sig-nals and improving the adaptability and robustness of arterial green wave coordination control schemes.

Optimization Method of Maximum Cycle Length Based on Back of Queue

Wang Dian- hai Fu Feng- jie Cai Zheng- yi Ma Dong- fang

2014, 42(5):  67-74.  doi:10.3969/j.issn.1000-565X.2014.05.011

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In order to fully consider the impact of Back of Queue (BoQ) on upstream node and avoid the queuespillover in short- linked sections,the evolution principle of queuing length in entrance lane is firstly analyzed byusing the traffic wave theory,and a method to calculate the distance from BoQ to stop line in saturation period isdeduced.Secondly,by taking the shortest distance of BoQ in critical line of critical phase as the optimizationobjective,a model to optimize the maximum cycle length is established.Then,8 types of testing environmentsmeeting different traffic requirements are designed,in which the proposed and existing optimization methods arecomparatively investigated by calculating the maximum cycle length and by determining the signal timing schemeson the basis of equi- saturation principle.Finally,the efficiencies of the two methods are evaluated in differenttesting environments via VISSIM simulation.The results show that the proposed method is more effective than theexisting one because the former helps reduce the average queuing length,the average distance from BoQ to stop lineand the average stops in critical line of critical phase,with the decrements respectively being 10.67%,11.36%and 11.01%; what's more,the proposed method also results in an average time delay decrement and an averagestop decrement of the whole test network of 3.86% and 3.81%,respectively,as well as an average vehicle numberincrement and an average vehicle speed increment of 1.19% and 3.58%,respectively．

Coupling Vibration Investigation and Parameter Analysis of Crowd- Bridge System

Chen Zhou Yan Quan- sheng Hu Jun- liang Huang Shi- ping Yu Xiao- lin

2014, 42(5):  75-83.  doi:10.3969/j.issn.1000-565X.2014.05.012

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According to the findings of traffic flow and biomechanics,a human body is considered to be a 2- DOF(Degree of Freedom) system with mass,stiffness and damping.A dynamic model of crowd- bridge coupling systemwith crowd being on the bridge is thus constructed.Moreover,the dynamic characteristics of the coupling systemaffected by the crowd are analyzed,and the dynamic response as well as the pedestrian- induced vibration parametersensitivity of the coupling system in different walking modes is investigated.The results show that (1) an additionalvibration mode of the coupling system may occur due to the presence of crowd; (2) crowd density and locationgreatly affect the dynamic characteristics of the coupling system; (3) the influence of walkers on bridge's dynamicresponse mainly depends on two factors such as whether the walking frequency is close to the vertical fundamentalfrequency of the structure and whether the crowd is of the same walking pace; and (4) both crowd density andwalking speed influence the dynamic characteristics of the crowd- bridges coupling system to different degrees.Theproposed model helps avoid the randomness of parameter selection for calculating the coupling vibration of crowdand structure.

Influence of Crossbeam Yielding on Transverse Seismic Response of Cable- Supported Bridge

Xia Xiu- shen Li Jian- zhong Xu Yan Ji Dong- bing

2014, 42(5):  84-89.  doi:10.3969/j.issn.1000-565X.2014.05.013

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The intensity of future earthquake is unpredictable.The tower in transverse direction of cable- stayedbridge may act in a nonlinear way in ultra- fortified earthquakes.In this paper,by taking a long- span cable- stayedbridge as the research object,a finite element model is established to analyze the transverse seismic response of ca-ble- stayed bridge under the action of strong earthquake.Then,the seismic capacity- to- demand ratio is introduced tojudge whether the crossbeam is yielding.Moreover,a fiber section beam element is employed to simulate the ine-lastic behavior of crossbeam,and the influence of crossbeam yielding on the transverse seismic response of cable-stayed bridge is finally investigated in detail.The results show that (1) as the seismic capacity- to- demand ratio ofcable- stayed bridge crossbeam is relatively small,a ductility design for crossbeam may be more reasonable; (2) theseismic axial force of crossbeam changes significantly,which may greatly affect the yielding moment; and (3) asthe yielded crossbeam greatly affects the transverse seismic response of cable- stayed bridge,the increasing bendingmoment of tower base should be considered in the design process.

Influence of Pipe- Burying Mode on Hydrothermal Snow Melting of Bridge Decks

Fu Zhen Wang Xuan- cang Lu Kai- quan

2014, 42(5):  90-96.  doi:10.3969/j.issn.1000-565X.2014.05.014

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In this paper,first,a numerical model was established with finite element program.Then,a thermody-namic simulation on the snow melting process of bridge decks in steady state was made by means of finite differencemethod.Finally,by taking mountain thermal spring water as a hot fluid medium,the influences of pipe- buryingdepth and pipe spacing on the temperature distribution and heat flux density of bridge decks were investigated at anambient temperature of －5℃,a surface wind speed of 2m/s and a water temperature of 15℃.The results showthat (1) there are dense isotherms and high heat flux density around buried pipes; (2) both pipe- burying depthand pipe spacing produce great impact on the distribution uniformity of deck surface temperature and heat flux den-sity; and (3) smaller pipe- burying depth and pipe spacing may result in higher deck surface temperature as well asheat flux density,and may accelerate snow melting and its velocity.Therefore,considering such comprehensivefactors as snow melting effect,construction and economy.it is suggested that pipe- burying depth should be 2 cmand pipe spacing should be 15cm.

Remote Sensing Image Recognition for Vehicles Based on Self- Feedback Template Extraction

Li Shi- wu Xu Yi Sun Wen- cai Yang Zhong- kai Guo Meng- zhuYang Liang- kun Yu Xiao- dong Wang De- qiang

2014, 42(5):  97-102.  doi:10.3969/j.issn.1000-565X.2014.05.015

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Due to the blank of template extraction technology,most efficient template matching algorithms are con-structed on the basis of artificial template extraction.The defects of current template extraction may reduce theaccuracy and stability of image recognition through their progressively spreading in recognition process,and finallyaffect the results of traffic state identification on the basis of remote sensing images.In order to solve this problem,a remote sensing image recognition method for vehicles is proposed on the basis of self- feedback template extrac-tion,and the correctness of self- feedback template extraction is demonstrated by mathematical derivations.Then,ahigh- resolution remote sensing image recognition and a traffic flow identification are carried out for several certainroad sections on the platform of Matlab.Finally,the feasibility and effectiveness of the proposed method are verifiedthrough analyzing the remote sensing image recognition results of several road sections.

Computer Science & Technology

Wastewater Effluent Quality Prediction Model Based on Relevance Vector Machine

Xu Yu- ge Cao Tao Luo Fei

2014, 42(5):  103-108.  doi:10.3969/j.issn.1000-565X.2014.05.016

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Considering the complicated process of biochemical sewage treatment,difficulty in precisely forecastingeffluent quality and relatively serious prediction error,a prediction model for the effluent quality in wastewater treat-ment is proposed on the basis of relevance vector machine.In this method,an attribute reduction is,first and fore-most,performed for input data by using fuzzy monotonic increasing dependence algorithm,and the final inputattributes are determined in combination with experience.Then,an effluent quality prediction model is establishedwith the help of relevance vector machine and the model parameters are subsequently optimized.Experimentalresults indicate that the proposed prediction model well meets the requirements of effluent quality forecasting due toits high prediction accuracy and strong generalization ability.

Virtual Machine Deployment Algorithm for Reducing Energy Consumption in Cloud Computing

Zhou Zhou Hu Zhi- gang

2014, 42(5):  109-114.  doi:10.3969/j.issn.1000-565X.2014.05.017

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In order to reduce the energy consumption of large- scale data centers,a virtual machine (VM) deploy-ment algorithm called TTEA (Three Threshold Energy- saving Algorithm) is proposed.TTEA makes use of the linearrelationship between energy consumption and processor resource utilization,and migrates the VMs on heavily- loadedand lightly- loaded hosts to the host with proper load,while the VMs on normally- loaded host remain constant.Then,on the basis of TTEA,four VM selection strategies are proposed and HLGP is chosen as the best one as aresult of experimental comparison.Simulated results indicate that,in comparison with the single threshold algorithmand the double threshold algorithm,HLGP strategy is more effective because it efficiently reduces the energy con-sumption of data centers and keeps high quality of service.

Facial Expression Recognition Referring to Neutral Expression

Zou Wen- jie Wang Wen- jing Yang Fu- zheng

2014, 42(5):  115-121.  doi:10.3969/j.issn.1000-565X.2014.05.018

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In order to fully explore the difference in facial expression in videos,a novel facial expression recogni-tion approach for non- repeatable face,which utilizes both dynamic and static features to recognize the facial expres-sion in videos in low- complexity scenarios,is proposed.In this approach,the feature point offset angle of neutralexpression is presented as a feature to represent the difference information of measured facial expression,and simul-taneously,the two- dimension principal component features are extracted via two- dimension principal componentanalysis (2DPCA).Then,the combined dynamic- static information is sent to support vector machine (SVM) clas-sifiers to implement the facial expression recognition.Experimental results on JAFFE database indicate that,incomparison with the existing method which only uses the static features extracted via 2DPCA,the proposed methodmay result in 7% of increment in facial expression recognition accuracy.

Feature Description Method for Freehand Sketch by Combining Entropy and Potential Energy

Zhao Peng Zhu Wei- wei Wu Xian- wen Liu Hui- ting

2014, 42(5):  122-127.  doi:10.3969/j.issn.1000-565X.2014.05.019

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In order to describe the shape of freehand sketch more accurately,a novel feature description method forfreehand sketch,which is of certain translation invariance,scale invariance and rotation invariance,is proposed bycombining entropy and potential energy.First,in this method,the key contour points in freehand sketch are extrac-ted,and the information entropy of each key point is computed by dividing the region around the point into severalsub- regions.Then,according to the spatial position of key point in the object of freehand sketch,the potentialenergy of key contour point is computed,from which the descriptor vector for the key contour point is obtained incombination with entropy and potential energy.Finally,all the descriptor vectors of key contour points in all trai-ning freehand sketches are clustered to construct a visual code book,on the basis of which a freehand sketch is de-scribed as a feature vector.Experimental results verify the effectiveness of the proposed method.

Generating Model of Test Case for Normalized Corner Floating- Point Multiplication Based on Hensel Lemma

Feng Chun- yang Yan Xin Yang Liang Huang Shi- tan

2014, 42(5):  128-134.  doi:10.3969/j.issn.1000-565X.2014.05.020

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In order to overcome the major drawbacks existing in the simulation- based verification of floating- pointmultiplication,such as too large test space,dissatisfying test coverage and difficult corner case location,a genera-ting model of test case for normalized corner floating- point multiplication is constructed on the basis of Hensel lemma.Then,the test case and product are discussed concerning both positively-and negatively- normalized corner floating-point numbers.The results indicate that,in comparison with the traditional corner verification method,theproposed method improves the average error- detecting rate by about 7.39%; especially,it helps achieve an error-detecting rate at different floating- point bit widths up to 9.77%.Thus,it is concluded that the proposed modeleffectively improves the functional coverage and reliability of floating- point multiplication.

SingleMapReduce: a MapReduce Programming Model Outputting Single HDFS File

Chen Ji- rong Le Jia- jin

2014, 42(5):  135-142.  doi:10.3969/j.issn.1000-565X.2014.05.021

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In order to obtain single HDFS (Hadoop Distributed File System) file that cannot be provided by classi-cal MapReduce programming model,a new MapReduce programming model named SingleMapReduce is presented.In this mode,all files in an output directory are consolidated into a single HDFS file by intercepting Job Successfulstate.Then,four features of HDFS are summarized,and two concepts including Typical Distribution of Block andAtypical Distribution of Block are proposed,on the basis of which metadata are integrated to obtain integrated files.The results of theoretical analysis and experiments show that (1) one MapReduce computing on the basis of Sin-gleMapReduce helps achieve single output file; (2) the output produced by one MapReduce computing can be splitvia file splitting; (3) one large- scale table or one large- scale file can be imported into HDFS in a parallel manner;and (4) SingleMapReduce supports the scalability of name node in auxiliary.

Improved LEM2 Rule Extraction Algorithm Based on Generalized Decision Function

Ji Xia Li Long- shu Xu Yi

2014, 42(5):  143-148.  doi:10.3969/j.issn.1000-565X.2014.05.022

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In order to improve the efficiency and quality of rule extraction in LEM2 series algorithms,an improvedLEM2 algorithm on the basis of generalized decision function,namely GDF- LEM2,is proposed.In this algorithm,candidate attribute- value pair set T(G) is calculated according to generalized decision function and is downsized bydeleting newly- defined redundancy attribute- value pair sets,and thus the efficiency of rule extraction is improved.Moreover,the choice of attribute- value pair sets is guided with the minimum intersection of generalized decisionfunction strategy,which makes the extracted rule more laconic and thus improves the quality of rule extraction.Ex-perimental results show that GDF- LEM2 algorithm effectively improves the efficiency and quality of rule extractionfrom complete or incomplete decision systems.