西南交通大学学报

FaultLocation System for Automatic Block and Continuous Transm ission Lines Based on S-InjectionM ethod

HE Zheng-you, LIWei-hua

2005, 18(5): 569-574.

[Abstract](1278)

Abstract:
A wireless-node communication network was designed to detect single-phase-to-ground faults in railway automatic blocking and continuous transmission lines by combining S-injectionmethod with wireless nodes. The system makes use of automatic net-organization function and high fault- tolerant characteristic ofsensornetworks. It is composed ofa signal injection device, wirelessnodes, a wireless process unitat the switch station and an intelligent faultdetection system. Signals are injected on awireless node. The intelligent faultdetection system receives the detected results transmitted from thewireless node and locate the fault position. Determined by simulations, the power source is of constantcurrentand its frequency ranges from 220 to 320Hz. The sensors are arranged in twomodes: parallel and interleaving. These two modes both meet the requirement of reliability for information transmission, but the reliability of the former is as triple as thatof the latter. The locating precision of the system is adjustable according to application.

Feed-Forward Intelligent Fuzzy Logic Control of H ighway TunnelVentilation System

HE Chuan, LIZu-wei, FANG Yong, WANGMing-nian

2005, 18(5): 575-579.

[Abstract](1447)

Abstract:
Fuzzy logic was applied to the feed-forward control of the ventilation system of a long highway tunnel to save electric energy and effectively solve the problems of the traditional control methods, such as time lag and fans frequent start-up. The constitution of the feed-forward intelligent fuzzy logic control system was presented, the fuzzy logic controllerwas designed particularly, and the feed-forward intelligent fuzzy logic control system was simulated numerically. The results indicate tha,t comparedwith the traditional feed-back controlmethod, this system can decrease energy consumption and extend the service life of fans greatly in the same conditions.

ExperimentalResearch ofW ind-Induced Responses of ChongqingM arriott InternationalConference Center Building

ZHENG Shi-xiong, XUE Shang-ling

2005, 18(5): 580-584.

[Abstract](1634)

Abstract:
To obtain thewind load andwind-induced responses of theChongqingMarriott International Conference Center Building, a tall steel structure building with a height of 303 m and the first frequency of0. 123 4 Hz, to evaluate its living comfortableness and safety, a wind-tunnelmodel test was carried outto simulate naturalwind in the turbulentboundary layeron the site of the building. The distribution ofwind pressure on every surface of the buildingwasmeasured by a staticmode,l and the static wind load was calculated. The wind-induced responses, including displacemen,t acceleration and angular velocity responses, were measured by an aeroelastic mode,l and the dynamic wind load was gained. The effects of its surrounding buildings and structureswere discussed. The result shows that the surrounding buildings have great effects on the wind load, no galloping will occur for the design velocity, the acceleration and angular velocity of the building top are smaller than their allowances and the living comfortability of the buildingmeets the related national code.

Analysis ofFlow Characteristics around H igh-Speed Railway Bridge-Vehicle System under CrossW ind

HUANG Lin, LIAOHai-li

2005, 18(5): 585-590.

[Abstract](1756)

Abstract:
An analysis was carried out for flow characteristics around a vehicle-bridge system consisting ofGerman ICE ( intercity-express) vehicle and standard simply-supported bridge under cross wind. Based on the two-dimensionalReynolds averaged incompressible Navier-Stokes equations, the RNG (renormalization group) turbulencemodelwas used in the numerical simulation. Triangulargrid and quadrilateral grid were used to divide the computational domain, the finite volume method was adopted to discretize the governing differential equations, and the pressure-velocity field was coupled using the SIMPLE (semi-implicitmethod for pressure-linked equations) algorithm. Furthermore, the research results of driven cavity flowswere applied to the analysis of flow characteristics around the vehicle-bridge system considering the wind-break wall effec.t The analysis shows that the wind-break wall of a high-speed railway bridge has the similar vortex characteristics of driven cavity flows in preventingwind.

Numerical Simulation ofReasonable Relative Position of Smoke Tower and Passageway of Subway Station

GUZheng-hong, CHENG Yuan-ping, ZHOU Shi-ning

2005, 18(5): 591-594.

[Abstract](1547)

Abstract:
FDS ( fire dynamics simulator), a field simulation software, was used to investigate the spread regularity of smoke and its influencing factors in order to determine the reasonable relative position of smoke tower and passageway ofa subway station to prevent the smoke extracted through the smoke towerwhen a subway fire occurs running back into the station. The simulation results indicates that the possibility that the smoke extracted through a smoke tower runs back into a subway station through its passageway is related to smoke temperature, spatial distance between a smoke tower and a passageway, and direction and strength of nature wind and so on. A field experiment shows the availability of the simulation results.

Research on 3D FEM Nonlinear SimulationM ethod for Shear Connectors

ZHANG Qing-hua, LIQiao, TANG Liang

2005, 18(5): 595-599.

[Abstract](1714)

Abstract:
Based on the finite elementmethod (FEM) and the constitutive model of concrete, a method of analyzing the mechanical behavior of shear connectors was put forward. This method includes FEM simulation analyses and verification experiments, but only few experiments must be carried ou.t The method was used to analyze the mechanical behavior of new type shear connectors classified into three types and seven sub-types. The validity of the proposed method has been demonstrated through the comparison between the simulated and experimental results to be able to investigate themechanicalbehaviors ofmany kinds of shear connectorswith themethod.

ExperimentalResearch on Shear Properties of New-to-O ld Concrete Interface

WANG Zhen-ling, LIN Yong-jun, QIAN Yong-jiu

2005, 18(5): 600-604.

[Abstract](1522)

Abstract:
Shear experiments were conducted on 18 Z-shape specimens from 6 different groups to investigate the shear properties of the interface of new and old concrete. The effects of different interfacial techniques,i. e., smearing cement paste, directly casting new concrete, and smearing commercial interfacial agents, on the shearpropertieswere investigated. The experimental results show that the interfacial techniques have a great effect on the shear properties of a new-to-old concrete interface. The shear strength of specimens is greatestwhen the technique of smearing cementpaste is used in the three interfacial techniques. Furthermore, reinforcing steel bar planting can improve the shear properties of the interface remarkably. The experiments show that the depth of reinforcing steel barplanting should be greater than ten times the diameter of a reinforcing steel bar in the repair and strengthening of structures.

Numerical Simulation ofCavity DevelopmentBased on Improved Calculation ofPlume Region

YANG Jun-liu, HEDan

2005, 18(5): 605-609.

[Abstract](1130)

Abstract:
To enhance the numerical simulation accuracy of cavity development in solution mining of rock sal,t a calculationalmethod for the concentration difference between the saltand themain region of cavitywas proposed by considering plume effects. The finite analytic method (FAM) was used to solve the turbulencemodel for a plume region, and then solute diffusion and convection in the plume region and itsneighboringmain regionwere calculated. Based on the above, amodel for concentration of salt in the main region was set up. A calculational example shows that the numerical simulation resultof cavity developmentobtainedwith thismethod accordswith the experimental result.

Ionospheric BiasesM odeling Technique for GPSMultiple Reference Stations

LICheng-gang, HUANG Ding-fa, YUAN Lin-guo, ZHOULe-tao, XURui

2005, 18(5): 610-615.

[Abstract](1488)

Abstract:
Four typicalmethods to describe the ionospheric biases at the roverpositionwere discussed to develop general formulas of correction generationmodels, both the advantages and disadvantages of each technique were summarized. Test data from both GPSNOS (GPS reference station network of Sichuan) and SCIGN (Southern California integrated GPS network) were used to evaluate the modeling techniques. The experimental results show that the linear interpolationmodel and the linear combinationmodel are more reliable network solution with a correction precision of 2 to 5 cm in reduction of the ionospheric biases for reference station networks with a baseline length of below 200 km.Real-time kinematic differential GPS positioning at cm-level can be considerably improved when the twomodels are used based on the virtual reference station technique to correct the systemic errors, including the ionospheric biases.

Supersymmetry of In-Group and“Out-Group”Particles and Some Strange Phenomena

JIAO Shan-qing, XUDi-yu, GONG Zi-zheng, CHEN Bo-tao

2005, 18(5): 616-620.

[Abstract](1383)

Abstract:
The symmetry of the in-group particles, which are of three generation fermions, and the “out-group”ones, which are not admitted by three generation fermions, was discussed. Itwas found that the“out-group”antiparticles of Bose type, which came into being because of CP ( charge conjugation-parity conservation) violation in the early universe and became heavier due to the phase transformation from low temperature to high temperature, are the supersymmetry companionsof the“in- group”particles of Fermi type. The mass of a neutralino, which is the lightest particle of the supersymmetry companions andmay be ofdarkmatter, was calculated to be about320 GeV. The ratio of the number density ofphotons to thatofprotons calculatedwith Planck distributionmethod is about 0. 6×1010, which is close to the observed value (about1010) available in literature. A photon has the quark-gluon structure according to an analysisof the relationship between itsmass and structure, which is consistentwith the experimental result reported in literature.

Search for TeV Gamma-Ray Bursts using Tibet-IIIAir Shower Array Data

ZHOUXun-xiu, HUANG Qing

2005, 18(5): 621-624.

[Abstract](963)

Abstract:
A search forTeV gamma-ray bursts (GRBs) was carried outby using the data ofTibet-III air shower array. About1. 45 billion eventswere analyzed. A GRB candidatewas chosen as a shower cluster appearing in a given small sky bin and a given time interva.l Themethod of equi-zenith angle was used to estimate the background. No significantTeV GRBswere detected. The flux upper limitat a 95% confidence levelwas estimated to be about10-9~10-7photons/(cm2·s) by theMonte Carlo simulation.

Preparation ofBiodegradableM icrospheres Containing Human Serum Album in

ZHOU Shao-bing, SUN Jing, ZHENGXiao-tong

2005, 18(5): 625-627.

[Abstract](1316)

Abstract:
Poly-DL-lactide-b-polyethylene glycol (PELA) block copolymerswere synthesized by ring- opening polymerization of lactide with polyethylene glyco.l PELA microspheres containing human serum albumin (HSA) were elaborated by the solvent extraction method based on the formation of doubleW1/O/W2emulsion. The microspheres with an idealmean diameter of 1. 36μm and a size distribution ranging from 0. 5 to 5μm were smooth and spherica.l The effects of concentration of alginate/CaCl2added in the internal water phase on the encapsulation efficiency ofHSA and the characteristics of the microspheres were investigated, and the content of protein in the microspheres was testedwith the CBB (Coomassie brilliant blue) method. The results show that the encapsulation efficiency is improved obviouslywhen the concentration of added alginate/CaCl2is 3. 0% (W /W) in the internalwater phase.

Dynam ic Compensation for Railway Line InformationM onitoring System ofTilting Train

WANGXue-mei, LING Jian-hui, LIFu, NIWen-bo

2005, 18(5): 628-632.

[Abstract](1459)

Abstract:
To improve the dynamic characteristics of themonitoring system ofa tilting train based on a single-axis gyroscope platform, a differencemodel to describe the dynamic characteristics ofgyroscope platformswas establishedwith the least squaresmethod and its improved algorithms, and the dynamic characteristics ofa gyroscope platform were analyzed. The corresponding dynamic compensation digital filterswere designed with the zero-pole matchingmethod. The simulation result shows that the delay time of superelevation signals is less than 0. 4 swith the designed digital filters tomeet the needs of real-time tilting control of tilting trains.

Application ofDigraph Theory to Process Scheduling

MAShu-wen, CHEN Yong, DUQuan-xing, ZHANG Jian-an

2005, 18(5): 633-636.

[Abstract](1418)

Abstract:
To set up an effective decision model of process scheduling, the digraph theory was applied. Based on the theory, processing features are expressedwith the vertices of a directed graph, and datum relationships among the processing features are describedwith directed edges. As a resul,t a directed path without a loop and through every vertex in the directed graph is a feasible process schedule. For computer processing of the directed digraph, it is expressed by amatrix, and then the longest directed paths can be obtained through matrices multiplication. If some vertices do not be included in a longestdirected path, these verticeswillbe inserted into the longestdirected path in the lightof the datum relationships so as to obtain satisfied process schedules.

Effect ofNumber ofTraining Samples on ANN Prediction Accuracy for Cutting Force

FAN Sheng-bo, WANG Tai-yong, WANG Wen-jin, DONG Ting-jian

2005, 18(5): 637-640.

[Abstract](1580)

Abstract:
In order to predictcutting force using training samples as few as possible, training samples with differentnumberswere selected to train an artificialneuralnetwork (ANN) respectively, and the effectof the numberof training samples onANN prediction accuracy for cutting force based on the LM (Lenvenberg-Marquardt) algorithm was analyzed by contrast experiments. Statistic mean amplitude and mean square errorwere taken as the evaluation indexes for forecast results, and the relationship between the prediction accuracy for cutting force and the numberof training sampleswas investigated. The research result indicates that 40 to 50 groups of training samples may be sufficient to obtain accurate cutting forcewithin the certain range of cutting parameters.

ToolW earM onitoring Based on Integrated NeuralNetworks

GAOHong-li, XUMing-heng, FUPan

2005, 18(5): 641-645.

[Abstract](1426)

Abstract:
A tool wear condition monitoring approach based on integrated neural networks was proposed to recognize and predicttoolwearconditions inmilling operations. In this approach, vibration and cutting force signals are decomposed into time sequences in different frequency bands bywavelet packet transform, and the rootmean square values of each signal in three frequency bands, extracted from decomposed signals, with a close relation towear conditions are selected asmonitoring features. The final recognition results of tool wear are given by the integrated neural networks through the combination of signals and the decision fusion of different subnets. Experiments and simulations show that the proposed approach canmeet the requirements ofon-linemonitoring of toolwear conditions.

Performances ofUWB W ireless Communication System s Based on Quadratic Time-Hopping Sequences

PENG Dai-yuan, YEWen-xia

2005, 18(5): 649-653.

[Abstract](1315)

Abstract:
Structures of the extended quadratic time-hopping sequences, the general class ofquadratic time-hopping sequences and some of their special kinds were discussed. Their Hamming cross- correlation propertieswere compared. Based on the discussion and comparison, the error rate of the ultra-wide band (UWB) systems with these quadratic time-hopping sequences and pulse position modulation (PPM) were compared, and the numerical resultswere presented. It is shown that these quadratic time-hopping sequences have the same system performance, and the general class of quadratic time-hopping sequences have a larger family size.

Instantaneous Parameters and Spectrum Analysis in M echanical Speed-Change Process

ZHANG Jie, CHEN Chun-jun, LIN Jian-hui

2005, 18(5): 654-648.

[Abstract](1362)

Abstract:
To enhance the analytical accuracy of vibration signals in a mechanical speed-change process, a non-linear relationship between the measurement systems of speed-change and the time varying statistic characteristics of the signalswas established by analyzing themeasurementprocess for a rotating machine. The Hilbert transform was applied to give the expression of instantaneous parameters of the signals. The research shows that the aberration of frequency spectra induced by the change of speed can be avoidedwhenmeasured signals are dealtwith through interpolation in light of the instantaneous frequency to gain the frequency spectra ofvibration signals.

DesignM ethod for Ultra-W ideband Pulse Based on the Parks-M cC lellan Algorithm

XIAO Shang-hui, JIANG Yi

2005, 18(5): 654-648.

[Abstract](1542)

Abstract:
According to the characteristics ofUWB (ultra-wide band) pulse waveforms, a new pulse shape design method for UWB radios based on Parks-McClellan algorithm was proposed. In the method, the pulse shape design is taken as optimal design of a FIR (finite impulse response) filter. TH ( time hopping) and PPM (pulse position modulation) technology was adopted for monocycle pulse, which optimally utilizes the bandwidth determined by the FCC ( federal communication committee)spectralmasks. The relevantdesigning results can be applied in both single-andmulti-band UWB systems.

VirusDetection Based on Rough Set and Bayes C lassifier

WENQi, PENGHong, XUZhi-gen

2005, 18(5): 659-663.

[Abstract](1587)

Abstract:
Rough set and Bayes classifier were integrated in virus detection. On the basis of the feature reduction algorithm of rough se,t the proposed method takes synthetically into account the influences of the dependency of condition features and decision-making features and those of the dependency among condition features on reduction. W ith the method, the limitation on the independence among attribute variables are relaxed, the potential robust properties ofBayes classifier are utilized and its performances are improved. Experiment results show that the detection rate is 97. 88%, and the accuracy is 97. 16%, superior to the signature-based method, RIPPER(repeated incrementalpruning to produce erroe reduction) and Bayesmethod; the false positive rate is 5. 19%, less than the othermethods.

Transition Region Extraction Algorithm Based on LocalFuzzy Entropy

ZHANG Chao, ZHANG Jia-shu, CHENHui, JIADong-li

2005, 18(5): 663-666.

[Abstract](1399)

Abstract:
To improve the performances of transition region extraction algorithmsundernoises, a novel local fuzzy entropy-based transition region algorithm was proposed by making improvement to the existing local entropy-based transition region algorithm. The proposed algorithm makes full use of the difference between transition regions and target regions (or background regions). The performance of the proposed algorithm was compared with the local entropy algorithm underGaussian noise and salt and peppernoise. The comparison shows that the proposed algorithm provideshigheraccuracy than the local entropy-based transition region extraction algorithm does under Gaussian noise, although both behavewellunder salt and peppernoise.

HybridM agnetic Suspension System Based on Zero Power Control Strategy

WANG Li, ZHANGKun-lun

2005, 18(5): 667-672.

[Abstract](1414)

Abstract:
A hybrid suspension system with permanent and electric magnets was designed, and its mathematicalmodelwas derived. A controllerwas designed based on zero power control strategy,i. e. the current in electromagnets ismaintained ataboutzero. Simulation shows thatwith this controller the system realizes stable suspension with large air gap and low power consumption. Compared with the system based on fixed gap control strategy, the hybrid suspension system based on zero power control strategy consumes much less energy with a little loss in suspension stability, although both of the systems provide stable suspensionwith large air gap.

M echanism and Influencing Factors ofOvervoltage on Inverter-Fed TractionM otor Term inal

TONG Lai-sheng, WUGuang-ning, WEN Feng-xiang

2005, 18(5): 673-676.

[Abstract](1406)

Abstract:
Overvoltage is one of the main causes of damage in the isolation of inverter-fed traction motors. To solve this problem, the mechanism and influencing factors were analyzed with the transmission line theory and simulation on the equivalentcircui.t The analyses show thatovervoltage is a function of the rise time of the converter output pulse and the lengths of the traction motor cables, and that its magnitude can be as large as 1. 9 times of the pulse voltage. The magnitude can be decreased to 1. 1 times of the pulse voltagewith a shuntR-C reactor.

Principle ofAssumed Temperature Reduced Thrust Takeoff

ZHAO Ting-yu

2005, 18(5): 677-679.

[Abstract](1464)

Abstract:
For correct and wide application of reduced thrust takeoff technique, the temperature characteristics ofhigh bypass ratio turbofan engines and the takeoffperformance of large aircraftswere analyzed. Assumed temperature is the equivalent ambient air temperature determined by the actual takeoffmass ofan aircraf.t The necessary conditions ofreduced thrust takeoffare that the actual takeoff mass is less than themaximum takeoffmass of an aircraft and that the assumed temperature is higher than the reference temperature. The rotation speed of the fan under assumed temperature reduced thrust takeoff is calculated based on the analogical condition of engine.

Transportation SafetyM onitor Information System for Gulmud-Lasa Line in Q inghai-TibetRailway

LUO Xiu-yun, PU Yun, CHEN Shang-yun

2005, 18(5): 680-683.

[Abstract](1551)

Abstract:
The influences of the environment on railway transportation safety on Gulmud-Lasa line in Qinghai-Tibet railway was analyzed, the necessity of a transportation safety supervision information system for the railway line was discussed. The initial design of the system was presented. In the design, the environment and facility arrangement along this railway are taken into consideration. Computernetwork technique andmodern equipmentare used to continuouslymonitor the environments and the operation status of the facilities. All distributed monitoring systems along the railway line are connected with the safety monitor center, realizing central management and share of information collected along the line.

Game Analysis of Information-Based M anipulation of SecuritiesM arket

ZHANG Yong-peng, QIUPei-guang, ZHUWei

2005, 18(5): 684-689.

[Abstract](1325)

Abstract:
An existingmodel available in literature wasmodified to degrade the accuracy of private information from an informer, so that he can manipulate the securities market repeatedly in a long period. The analysis result shows tha,t the informer has tomake the public believe in his honesty to lead the publics' believes in the assets and manipulate themarke.t The long-period equilibrium of an informerwhomay change his statuses between honesty and dishonesty is that it is impossible for the public to fully know his status, information transferkeeps on and his creditability ismore than 1/2.

M onopoly and Regulation in the Reform ofElectricity Industry in China

TIANHong-yun, CHEN Ji-xiang

2005, 18(5): 690-695.

[Abstract](1240)

Abstract:
To study the problem ofmonopoly in the electricity industry in China, a game theorymodel was designed according to the demand characteristics in the electricity market and by applying the theory ofmonopoly and regulation. The result indicates that the electricity producing companies have strong collusionmotivation; and thatnaturalmonopoly exists in the electricity transmissionmarke,t and new monopoly is easy to form due to the special position of electricity transmission companies. Administrativemonopoly is a significant obstacle for formation of effective competition in both the electricity producing and transportation markets. At las,t the measures of solving monopoly problem were suggested.

Dynam ic Pricing Policy of the SeasonalProducts Based on RevenueM anagement

GUAN Zhen-zhong, HUANG Shen-ze, SHIBen-shan

2005, 18(5): 696-699.

[Abstract](1498)

Abstract:
To gain maximum expected revenue, dynamic pricing policy of seasonal products was studied based on revenue managemen.t A continuous-time dynamic pricing model with customer reservation pricewasproposed. The optimal solutionwas obtained under the condition thatdemand is a Poisson process and reservation price is exponential distribution. Simulation shows that the optimal price is a decreasing function of initial inventory and an increasing function ofsale period and potential buying probability; expected revenue is an increasing function of remaining sale period and initial inventory, butmarginal expected revenue is a decreasing function of initial inventory.

Multi-stage OptimalOrdering Strategy for theM anufacturer under Uncertain Prices

YANG Qing-ding, HUANG Pei-qing

2005, 18(5): 700-704.

[Abstract](1403)

Abstract:
To study multi-stage optimal ordering strategies for the manufacturer under uncertain prices, a stochastic netcash flowmodelwas proposed in view of themanufacturer. In themode,l it is assumed that the supply chain is composed of a single manufacturer and a single supplier from any country in theworld, their contract is quantity-flexible, exchange rate changes as geometric Brownian motion, and out-of-stock is allowable by themanufacturer. The optimal strategies can be obtained by solve the model with binomial lattice method. The efficiency for solving the model is positively dependenton the number ofordering and the size of the feasible solution setof every ordering period. The feasibility of themodel and the algorithm for solving itwere verifiedwith an example.

Incentive Entropy andW arningM echanism of Incentive System for Firms

XIAO Wen, LIShi-ming

2005, 18(5): 705-709.

[Abstract](1556)

Abstract:
According to the theory of system managemen,t the incentive system, a sub-system of firm system subordinates the law ofentropy increase. An incentive system produces incentive entropy during its operation, resulting in a decrease in incentive efficiency. Therefore, incentive entropy can be used asmeasurementofdynamics of an incentive system. An incentivewarningmechanism was established to provide firmswith a method to optimize their incentive systems in the right time by observing the changes and the time of the changes of incentive entropy. The incentive system for the high administrative levelofa firm is the key to thewhole incentive system, and it isdependenton the initial state. Through the“butterfly effect”, the whole incentive system can be improved by raising the efficiency of the incentive system for administrative level.

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2005 Vol. 18, No. 5