Journal of South China University of Technology(Natural Science Edition)

Characteristic Analysis of Indoor Radio Wave Propagation by FDTD Method

Ji Fei, Huang Xiu-xuan, Chen Fang-jiong, et al

2004, 32(4): 1-4.

Asbtract ( 87 )

PDF (593KB) ( 565 )

Related Articles | Metrics

The propagation characteristics of the indoor radio wave with an important frequency of about2．4GHz in the radio intranet of IEEE802．11b were analyzed by the two-dimension FDTD （finite-different time-domain）method．The cumulative distribution probability and the power distribution of the received signal with the propagation distance were also given for the exciting source of2．4GHz continuous wave．The time-delays of the received signal for the line-of -sight and the non-line-of -sight scenarios with the impulse wave as the exciting source were then analyzed．The simulation results show thatbecause of the serious dispersionthe probability that the received signal power is higher than the average one when there is indoor furnitureis proved to be lower than when there is no furniture．

A Design of Dual Uniform Linear Array Based on the Method of DOA Estimation with FFT

Liu Xue-bin Wei Gang Ji Fei

2004, 32(4): 5-10.

Asbtract ( 128 )

PDF (254KB) ( 876 )

Related Articles | Metrics

Based on the traditional direction of arrival（DOA） estimation method of spatial signals by means of FFTa dual uniform linear array and the relevant DOA estimation method were designed for spatially confined signals．Both the deducted theory and the simulated result confirm that the proposed DOA estimation method based on the dual uni -form linear array can solve the problem of angle ambiguity．At the same timeit can geminate the angle resolution and obviously decrease the computationwhen compared with the general DOA estimation method based on the uniform linear array with the same antennas number and the interelement spacing of half -wavelength．

Manufacture and Properties of the Brass-piezoelectric Ceramic Composite Actuator

Shen Xing Yuan Shen-fang Wang Xin-wei ChenYong

2004, 32(4): 11-14.

Asbtract ( 95 )

PDF (489KB) ( 491 )

Related Articles | Metrics

A brass-piezoelectric ceramic composite actuator with a large displacement and a good load-bearing capabil -ity was manufactured by agglutinating and solidifying the cavity brass and the ceramic with conductive glue．The piezoelectric coefficient of d 33 more than2000pC／N was obtained in experiments．The piezoelectric and displacement properties of the actuator were systematically analyzed and the relationship between the geometric parameters and the actuating properties of the actuator was discussed．The results show that the cavity positioned between the metal end caps and the ceramic can convert and amplify the radial displacement of piezoelectric ceramics into a larger axial dis-placement of the whole structureand that with the decrease of brass thicknessthe resonant frequency of the actuator decreases obviouslywhile the axial displacement increases obviously．

Transmission Routings of Coordination Messages for the Optimal Management of Large-scale Networks

Huang Sheng-ye, Li Jian-xiang, Ye Wu, et al

2004, 32(4): 15-18.

Asbtract ( 109 )

PDF (182KB) ( 356 )

Related Articles | Metrics

The transmission of coordination messages caused by the decomposition-coordination process in large-scale networks was investigated．Two principlesone is that the shortest total distance from the central agent to other agents is the minimum one of the distances of all possible schemesthe other is that the time cost of the message transmission from the central agent to other agents following the shortest distance is also the minimum onewhich are used to select the central agent were proposed according to two different optimized objectivessuch as the minimum communication cost and the minimum waiting time of each agent．The corresponding routing algorithms for coordination messages were also provided．An example was finally given by which the process of selecting the optimal central agent via the two al -gorithms was illuminated．

Stereo Monitoring Information Service System for the Oceanic Dynamic Environment of the Taiwan Strait

Chi Tian-he, Zhang Xin, Wang Qin-min, et al

2004, 32(4): 19-22,27.

Asbtract ( 221 )

PDF (196KB) ( 425 )

Related Articles | Metrics

According to the characteristics of the oceanic dynamic environment of the Taiwan Straitthe construction scheme of the stereo monitoring netwhich generates the advanced achievements of oceanic dynamic environment moni - toring technology in our countrywas discussed．To meet the demands of information sharing and service of the net four details were investigatedincluding the classification system of service objectsthe division of service layersthe total structure of the service system and the technology strategy on the basis of data warehouseGISWebGIS and so on．

Soft Sensing Method for the Kappa Number of Pulp Under Complex Working Conditions

Zhang Jian, Li Yan, Huang Dao-pin, et al

2004, 32(4): 23-27.

Asbtract ( 126 )

PDF (169KB) ( 395 )

Related Articles | Metrics

During the research and application processes of the soft sensing technology for pulp Kappa numberthe pre-dicting precision decrease of the soft sensing method under complex conditions based directly on experiential models was observed．To overcome this problema new soft sensing method was introduced．In this methodthe characteristic in-formation of temperature-rising process extracted by Daubechies wavelet transform was used to classify the producing con-ditionsand a classified prediction model of Kappa number was then proposed．It is proved by the analysis of130sample data from a certain pulping workshop thatunder complex working conditions and comparing with the results by the meth-ods based directly on experiential modelsbetter prediction results would be obtained by the proposed method．

Dynamic Zoning Calculation of Elevator Traffic Based on Artificial Immune Algorithm

Li Zhong-hua Mao Zong-yuan Wu Yi-lin Wu Jian-ping

2004, 32(4): 28-32.

Asbtract ( 144 )

PDF (200KB) ( 704 )

Related Articles | Metrics

Based on the artificial immune algorithma novel calculation approach of the dynamic zoning during the elevator peak-traffic was proposed．The theory of the artificial immune system was describedthe dynamic zoning model of elevator traffic was clearly outlinedand the artificial immune algorithm for the model was then designed．This algorithm has the advantage of fast convergence and is utilized to quickly locate the optimal or sub-optimal zone of elevator trafficwhich is helpful to improve the rea- l time capability of the dynamic zoning．Simulation results indi -cate the practicability of the proposed algorithm．

Precise Automatic Image Registration Method of the Defect Detection for Ceramic Tiles

Su Cai-hong Zhu Xue-feng Liu Di

2004, 32(4): 33-36,42.

Asbtract ( 106 )

PDF (249KB) ( 551 )

Related Articles | Metrics

A precise automatic registration method of the defect detection for ceramic tiles with deterministic patterns was investigated．The four edges and the left -above corner of the tile were located by the preprocessing and edge detec-tion of the image．Firstlythe displacement and rotation angle between the reference tile and the tile to be inspected were primarily estimated．Then shift and rotate the tile to be inspected in order to make its left -above corner aim at that of the reference tilethus completing a primary registration．Secondlymore precise displacement parameters were ob-tained by the cross-correlation method and were then utilized to make a precise registrationthus carrying out the defect detection directly between the pixels．Experimental results indicate that the proposed method can be effectively used to detect common defects such as holes and cracks．

Multi-clue Retrieval System for Trademark Images Based on the Fractal Dimension

Jiang Jin-shan Li Yue-qing Wang Guo-qiang

2004, 32(4): 37-42.

Asbtract ( 101 )

PDF (233KB) ( 343 )

Related Articles | Metrics

The retrieval technique based on image content was adopted to retrieve images according to the similarity matching between queried images and target images．The image content is depicted by five featuresnamelythe fractal dimension and fractal vector of the imagethe fractal dimensions of the image edge and the image skeletonand the distance distribution histogram．This system is of the advantages of friendly interface and plenteous functions．Experimental results indicate that the system is of perfect retrieval effect on trademark images and is of excellent inflexibility of displacementscale and rotationand that the image can certainly be retrieved by the system if it exists in the image database．Besidesthe system is proved to be robust．

Analyses of Factors Affecting the Ultrasonically-enhanced Supercritical Fluid Extraction of EPA and DHA from Algae

Qiu Tai-qiu, Ding Cai-mei, Hu Ai-jun, et al

2004, 32(4): 43-47.

Asbtract ( 137 )

PDF (206KB) ( 424 )

Related Articles | Metrics

Factors affecting the ultrasonically-enhanced supercritical fluid extraction （USFE） of EPA and DHA from algae were studiedincluding the temperaturepressure and time of the extractionCO 2 flowrate and ultrasonic parameters．Compared with supercritical fluid extraction （SFE）USFE makes CO 2 flowrate and the temperaturepressure and time of the extraction decreasewhile the extration yields of EPA and DHA increase．On the basis of singl- efactor experimentsan orthogonal experiment was carried out．The results indicate that the extraction undertaken at the extraction temperature of35℃ and the pressure of25MPa for a extraction time of3．0h and with a CO 2 flowrate of3L／h is the optimum technology approach to extract EPA and DHA by USFE．

Effect of Mixed Alkali on the Thermal Stability of Tellurite Glasses

Chen Bing-yan Chen Dong-dan Liu Yue-hui Jiang Zhong-hong

2004, 32(4): 48-51.

Asbtract ( 90 )

PDF (183KB) ( 573 )

Related Articles | Metrics

Tellurite glasses of0．7TeO 2 －0．2ZnO－xR 2 O－（0．1－x）R′2 O with various mole ratios of Li 2 O to Na 2 OLi 2 O to K 2 O and Na 2 O to K 2 O were prepared．With the measurement of vitrification point T g and crystalliza-tion temperature T x by DSCthe effect of the mixed alkali on the thermal stability of tellurite glasses were investigat -ed．The results indicate that the glass system is of excellent thermal stability when the mole ratios of Li 2 O to Na 2 OLi 2 O to K 2 O and Na 2 O to K 2 O are respectively14∶23∶and14∶and that the0．7TeO 2 －0．2ZnO－xLi 2 O－（0．1－x）K 2 O glass system is generally more thermally stable than the0．7TeO 2 －0．2ZnO－xLi 2 O－（0．1－x）Na 2 O systemwhile more unstable than the0．7TeO 2 －0．2ZnO－xNa 2 O－（0．1－x）K 2 O system．

Structure Characterization of Nanosized Cerium Oxide Particles Prepared by Homogeneous Precipitation

Yuan Wen-hui Bi Huai-qing Wei Chao-hai

2004, 32(4): 52-56.

Asbtract ( 121 )

PDF (134KB) ( 227 )

Related Articles | Metrics

A novel synthesis method based on homogeneous precipitation using cerium （Ⅳ） nitrate as the starting material was developed to prepare ultrafine cerium oxide particles．Properties of the obtained samples were characterized by XRDDSC／TGATEM and BET area measurements．A structure of fluorite cubic phase of the prepared samples with a BET specific surface area of101m
2 ／g was obtained．XRD results show that the prepared particles are of a large lattice parameterwhich indicates that the particles are very small．Moreoverthe DSC／TGA measurement results show that the weight loss of the particles is about 16．84％manifesting that the molecularformula of cerium oxide compound is CeO 2 ·2H 2 O．It is also indicated by TEM that the particles obtained by the
homogeneous precipitate method are spherica- l likewith an average particle size of about10nm．The sols obtained from CeO 2 particles are of the highest CeO 2 mass concentration of more than170g／L and are stable for more than four weeks without any precipitation．

NC Programming for Intricate Ruled Surfaces and Inclining Angle Verification of Ruling in Wire-EDM

Zhai Hong-jun, Liu Zheng-xun, Wang Wei, et al

2004, 32(4): 57-60,65.

Asbtract ( 92 )

PDF (211KB) ( 406 )

Related Articles | Metrics

Based on the machining principle analysis of the nature ruled surfacesthe technologies of NC program-ming for intricate nature ruled surfaces by wire-EDM were studiedincluding the profile marking standardthe algo-rithm of seeking corresponding pointsequa- l error synchro-linear approximation of profiles and the method to calculate the maximum inclining angle of ruling．It is found that less approximated curves and shorter NC codes can be obtained when the equa- l error synchro-linear approximation is employed to approximate the profile curvesand that the maxi -mum inclining angle of ruling can be efficiently obtained via the proposed calculation method during programming pro-cess．All the technologies mentioned above are verified and applied in the proposed NC programming system for low-speed wire-EDM．

Ploughing-extrusion Machining Mechanism of the Integra-fin of Stainless Steel Surface

Liu Ya-jun, Yang Zhuo-ru, Wan Zhen-ping, et al

2004, 32(4): 61-65.

Asbtract ( 119 )

PDF (624KB) ( 392 )

Related Articles | Metrics

Based on the experimental research on the fin formation mechanism by ploughing-extrusion machiningthe formation characteristicsmachining conditions and formation mechanism of the3D integra- l fin of stainless steel were investigated．The experimental results show that the influence on the fin formation attributes to such factors as tool ge-ometry parameterploughing-extrusion depthfeedploughing-extrusion velocity and the superposition angle of the secondary ploughing-extrusion．The reasonable values of matching parameters obtained by experiments are：the inclination angle of the ploughing face10°～35°；the extrusion angle10°～25°；the ploughing-extrusion velocity5～10m／min；and the feed0．4～0．8mm．

Finite Element Analysis of Ring Carrier Breaking in the Piston of Medium-speed Diesel Engine

Wu Jian Wang Jing-zhi

2004, 32(4): 66-69.

Asbtract ( 127 )

PDF (598KB) ( 530 )

Related Articles | Metrics

In order to reduce the stress concentration and avoid the breaking of the ring carrier in the piston of a cer-tain medium-speed diesel engine under thermal load3D finite element models of the piston and the ring carrier were establishedwith which the finite element calculation and analysis of the temperature fieldthe thermal deformation and the stress field for the ring carrier were carried out．The temperature field and the thermal deformation were con-sidered as the boundary in the calculation of the stress fieldthus obtaining an integrated stress field of the ring carrier under thermal load．The consistency between the finite element analysis result and the actual result reveals that the two methods of separate analysis and freedom degree coupling on the interface of the piston and the ring carrier are adaptive to the stress analysis of the ring carrier under thermal loadwith the advantages of simpleness and practicality．The an-
alyzed results show that a greater stress concentration would appear in the fixing hole of the ring carrier and that the
structure fault of the fixing hole is one of the main reasons for the ring carrier breaking．

Matlab/ Simulink Simulation Model of the Three-phase Induction Motor in Stator Winding ABC Frame

Yang Xiang-yu Shen Hui-yang

2004, 32(4): 70-73,91.

Asbtract ( 152 )

PDF (281KB) ( 1022 )

Related Articles | Metrics

Proposed in this paper is a mathematical model of the three-phase induction motor in the three-phase stator winding ABC frame．In this modelthe variable values of voltage and current are just the true values of those in the stator winding．This model is of the advantage of non-transformation of voltage or current between the converter and the stator when applied to the motor control system including converter circuitand is of the same superiority as the dq frame model．A simulation model for this mathematical model was then structured by Matlab／Simulink and was veri - fied by an example．The results show that the simulation results accord well with the actual valueswhich indicates the validity of the proposed model．

Mechanism Design and Mechanics Model of the Platform Screen Doors for Subways

Chen Hai-hui

2004, 32(4): 74-77.

Asbtract ( 147 )

PDF (119KB) ( 815 )

Related Articles | Metrics

Proposed here is a mechanism scheme of the platform screen doors （PSD） for subways．In this schemethe mechanism structure is composed of four modular units and is equipped with a3D adjustable bottom supporter and flexible top supporter．The constitution and function of the main mechanical parts are expounded．The external loads on PSD are investigated and the working condition as well as the verification criterions are presented．The mechanics model is simplified by the presumption that all parts consist of panel units and beam units．This scheme can satisfy the special requirements of subway stations on PSDand the dynamic model reflects the actual working conditions of PSD．

Calculation Method for Wide- flat Beam-slab Structures

Zhou Yu Han Xiao-lei Ji Jing

2004, 32(4): 78-81.

Asbtract ( 123 )

PDF (188KB) ( 909 )

Related Articles | Metrics

With reference to the slab strip model in the ACI building code and by using the finite element methodthe behavior of a wide-flat beam-slab structure under vertically load was investigated．The variation of the distribution co-efficients of the column-strip bending moments with beam widthbeam heightslab thicknessgrid span and column section sizeas well as the bending moment ratices of the beam were presented．By the variation analysis of the distri - bution coefficients vs．the relative stiffness coefficientit is found that the moment distribution in column strips could not be discussed only according to the relative stiffness coefficient and the grid span ratio in two directionsjust like that in ACI building codethat beam width is also a very important variable for the wide-flat beam-slab structure．on the basis of the above analysis resultsa calculation approach of inner force for wide-flat beam-slab structure was pro-posed．

Low-temperature Anti-cracking Performance of Fiber-reinforced Asphalt Mixture

Chen Hua-xin Zhang Zheng-qi Hu Chang-shun

2004, 32(4): 82-86.

Asbtract ( 1950 )

PDF (268KB) ( 1072 )

Related Articles | Metrics

Based on the micro-characteristics of fibers and the penetration test of fibrous asphalt gelas well as the low-temperature bending-creeping test of fiber -reinforced asphalt mixtures with3kinds of proportionsthe effects of fiber addition and proportion on the low-temperature ant- i cracking performance of the mixture were analyzed．The mechanism of performance improvement resulting from fiber addition was then investigated by means of the compound-material theory．The results reveal that the addition of fibers can evidently improve the low-temperature ant- i cracking performance of the fiber -reinforced asphalt mixtureand that polyester fiber has the most remarkable effect on the per-formance improvement．

One-dimension Viscous-plastic Constitution of Aluminum Foam

Hu Ling-ling, Huang Xiao-qing, Zhang Hong, et al

2004, 32(4): 87-91.

Asbtract ( 98 )

PDF (390KB) ( 786 )

Related Articles | Metrics

Proposed in this paper is a mathematical model of the three-phase induction motor in the three-phase stator
winding ABC frame．In this modelthe variable values of voltage and current are just the true values of those in the
stator winding．This model is of the advantage of non-transformation of voltage or current between the converter and
the stator when applied to the motor control system including converter circuitand is of the same superiority as the dq
frame model．A simulation model for this mathematical model was then structured by Matlab／Simulink and was veri -
fied by an example．The results show that the simulation results accord well with the actual valueswhich indicates the
validity of the proposed model．

Solitary Wave Solution and Its Numerical Analysis in a Nonlinear Elastic Bar

Han Qiang Zheng Xiang-feng

2004, 32(4): 92-96.

Asbtract ( 132 )

PDF (2279KB) ( 461 )

Related Articles | Metrics

The general form of the nonlinear wave equation in a nonlinear elastic bar was derived．An asympto-tic solution of the solitary wave was obtained by means of the modified complete-approximate method and was numerically analyzedfrom which two kinds of solitary waves—the bel- l type solitary wave and the oscillatory-type solitary wavewere found．Theoretical and numerical analyses indicate that the solitary wave is caused by the action of the material nonlinearity and the lateral effect of the barand that the propagation velocity of the solitary wave is related to its amplitudei．e．the larger the amplitude isthe larger the propagation velocity is；and that the wave width is of inverse ratio with the square root of wave propagation velocity and is related to the parameter indicating the dispersion effect of the wave—the larger the propagation velocity isthe shorter the wave width is．

Resolution of the Traveling Salesman Problem with Precedence Constraint Applying Genetic Algorithm

Zhu Ling-xiang Liao Qin Zou Liang

2004, 32(4): 97-100.

Asbtract ( 122 )

PDF (193KB) ( 1064 )

Related Articles | Metrics

The Traveling Salesman Problem with Precedence Constraint （TSPPC） was introduced and the localization of the general genetic algorithm （GA） to solve TSPPC was pointed out．It is found that a lot of illegal chromosomes would be generated by using the general GAthus reducing the searching efficiency of the algorithm．To overcome the disadvantages mentioned abovethe species initializationcrossover and mutation based on the precedence constraint of TSP were proposed．None of these genetic operations would generate any illegal chromosomewhich makes the searching efficiency of the algorithm higher．This conclusion was finally verified by corresponding theorems and examples．

Table of Content