西南交通大学学报

Dynamics and Service Simulation for General Coupling System of High-Speed Trains

ZHANG Weihua, ZHANG Shuguang

2008, 21(2): 147-152.

[Abstract](2152)

Abstract:
A theoretical dynamics framework for the general coupling system of high-speed trains was proposed according to the operational features of high-speed trains and the demand to study dynamics of the high-speed train system.In the framework,the track,catenary and air flows are coupled with the high-speed train.A model for the general coupling system was built with substructural method,where the substructures are coupled by forces or movements.A concept of service simulation and its necessity were discussed to improve the operational safety and reliability of high-speed trains.Suggestions on failure modeling of materials,structures and parameters,as well as the procedure,method and research scope of service simulation,were presented.

Method of Arrival and Departure Tracks Utilization Plan in Railroad Passenger Station Based on Ant Colony Algorithm

LÜ, Hongxia, HE Dake, CHEN Tao

2008, 21(2): 153-158.

[Abstract](1544)

Abstract:
A 0-1 programming model for utilization of arrival and departure tracks in a railroad passenger station was proposed,and the model was solved by an ant colony algorithm.In the algorithm,the pheromone is expressed with the ratio of the theoretically optimal objective function value to the actual objective function value,the heuristics information is defined as the reciprocal of weight of trains,and local searches are realized by a 2-opt method.Trains in a station are sorted according to the density of trains in a concerned time period and its influences on other trains to improve the solutions and for quick convergence of the algorithm.Then the sorted train sequence is taken as the order to obtain the solution to the model.The feasibility of the proposed method was verified by data from Harbin railroad passenger station.

Optimization for Static Wagon-Flow Allocation in Bidirectional Marshalling Station

XUE Feng, WANG Ciguang, LUO Jian

2008, 21(2): 159-164.

[Abstract](1416)

Abstract:
Definitions such as wagon-flow allocation time spans and feasible wagon-flows, etc,were presented.A bi-level multi-objective decision model was established,in which the objective functions include the total cost for removing wagons to unwanted directions and those without enough time to be transferred to a proper yard,and number of wagons to be transferred.The model was solved using a tabu search strategy and a wagon-flow allocation network.An example verifies that a feasible wagon-flow allocation scheme can be determined through directing arrival trains to a proper yard to realize wagon-flow allocation optimization of two break-up and make-up systems in a bidirectional marshalling station,and to make all departure trains,except pick-up and drop trains,fully-loaded and on time.

Method for Calculating Intersection Diversion Ratio Based on Network Equilibrium

CHENG Lin, YU Chunqing, WANG Wei, XU Xiangdong

2008, 21(2): 165-172.

[Abstract](1426)

Abstract:
A method for calculating intersection diversion ratio was proposed to study the influences of space distribution of traffic demands on traffic network bottlenecks.Link proportion,intersection diversion ratio and their relationship were investigated over stochastic user equilibrium networks.On the basis of Dial load, the formulae for single and double link proportions were derived following the probability principle and weight theory.A method for calculating intersection diversion ratio and flow was presented based on the obtained link proportions and the relationship between MSA algorithm and Dial load.A numerical example was presented to illustrate the feasibility of the proposed method.

Dynamics Simulation and Identification System for Road Accident Black-Spots

SHAO Yiming, HU Yan, YU Zhigang, XU Jin

2008, 21(2): 173-176.

[Abstract](1665)

Abstract:
A whole vehicle model of multi-body dynamics,a road model,and a tire-road surface coupling model were built using the multi-body dynamics analysis software ADAMS.A simulation system for identifying road accident black-spot was obtained based on the three models.Situations of running on a sharp curve at different speeds were simulated.Simulation results agree reasonably with dynamics of automobiles.

Mechanism of Run-Off-Road on Horizontal Curves Caused by Collision Avoidance of Vehicles

XU Jin, SHAO Yiming, PENG Qiyuan, CHEN Yongxi

2008, 21(2): 177-181.

[Abstract](1504)

Abstract:
Dynamic responds of a vehicle during collision avoidance were obtained through simulation.The curvatures of the traveling path for collision avoidance of two vehicles running in opposite directions were analyzed according to the lateral forces acting on tires.An excessive additional curvature caused by collision avoidance causes a vehicle to run off road on a horizontal curve.From the safety point of view,a vehicle should decrease speed as early as possible before collision avoidance to avoid excessive additional curvature and centrifugal forces,and go back to its normal path gradually.

Simulation of Flashover Conditions in Passenger Vehicles

LEI Bing, WANG Qingyuan, LIU Yingqing

2008, 21(2): 182-186.

[Abstract](1742)

Abstract:
A flashover model of high temperature smoke layer was derived based on energy conservation functions.A catastrophe potential function,which has the same form of swallowtail catastrophe,was obtained by dimensional normalization and diffeomorphism.The relationship between system control variables and burning conditions of fires in a passenger vehicle was studied.The catastrophe bifurcation of the control variables divide a fire into flashover zone and non-flashover one.In the flashover zone,an unstable point can be obtained from the characteristic curve and differential coefficient curve of the potential function.The temperature of high temperature smoke layer for a flashover to occur is then calculated from the unstable point.A calculation case shows that the temperature of high temperature smoke layer is 898.3 K when flashover occurs in a passenger vehicle,which agrees reasonably well with experimental results.

Dynasearch Algorithms for Solving Time Dependent Traveling Salesman Problem

LI Yanfeng, LI Jun, ZHAO Da

2008, 21(2): 187-193.

[Abstract](1523)

Abstract:
A method was proposed to solve the time-dependent traveling salesman problem(TDTSP) happening in more than one time period,and its model was derived.The model was solved with dynasearch algorithms,ds-k-opt(k=2,2.5,3).Simulation results show that some of the ds-2-opt solutions and most of ds-3-opt solutions are better than those of dynamic programming heuristics,and the dynasearch algorithms can solve a TDTSP with a larger scale.With an increase in k,solutions become better,while the computation time becomes longer.

Vibration Reduction Strategies of Controllable TMD-Hybrid Tanks System

TAN Ping, HUANG Dongyang, DAI Naxin, ZHOU Fulin

2008, 21(2): 194-199.

[Abstract](1615)

Abstract:
Excursions of structures’ frequencies,result from engineering vibration or discrepancies between structures’ actual frequencies and designed ones due to calculation or construction errors,will make the vibration reduction effect of a passive tuned damper drop obviously.In order to improve the detuning effect of a passive tuned damper,a controllable TMD-hybrid tanks system(CTHTS) was proposed.Horizontal baffles in this system are switched to deal with the frequency excursion of a structure.The setting of parameters in the system was discussed,and the motion equations for TLCD(tuned liquid column damper),TLD(tuned liquid damper) and a structure with THTS(TMD-hybrid tanks system) are derived.A numerical example was used to compare the control performance of CTHTS and ordinary TMD(tuned mass damper).The research results show the advantage of the CTHTS and the effectiveness of the strategies.

Earthquake-Induced Added Hydrodynamic Pressure on Circular Hollow Piers in Deep Water

LIU Zhenyu, LI Qiao, ZHAO Chanhui, ZHUANG Weilin

2008, 21(2): 200-205,212.

[Abstract](1879)

Abstract:
Based on the radiation wave theory,a liquid control equation for hollow circular piers was deduced under the condition of free surface wave,the movement boundary condition of bottom water particles,and the continuity condition of structure and water velocities.By applying the variable separation method,a method of calculating the velocity of water in the inner area of a hollow circular pier was gained.Furthermore,an analytical method for added hydrodynamic pressure of water in the inner area of a hollow circular pier was proposed.A calculation of the added hydrodynamic pressure for Rion-Antirion bridge in Greece shows that the added hydrodynamic pressure will result in the increases of bent moment and shear force,and the effect of water in the inner area of a hollow circular pier can not be neglected.

Experimental Investigation on Ductility of U-Section Steel-Encased Concrete Composite Beams

SHI Qiyin, HUANG Zhouyu, LI Aiqun

2008, 21(2): 206-212.

[Abstract](1756)

Abstract:
An experiment was conducted on nine U-section steel-encased concrete composite beams,and the relationships of the ductility of the composite beams and their failure modes were probed into to investigate the ductility of this type of composite beams.From the experimental results,main factors influencing the ductility of a U-section steel-encased concrete composite beam,including concrete flange width,shear connection coefficient,concrete strength,transverse reinforcement ratio and steel yield strength,were discussed based on the grey system theory,and the effects of these main factors on the ductility of the composite beams were analyzed quantitatively using a finite element analysis software ANSYS.In addition,a simplified formula predicting the displacement ductility coefficient of U-section steel-encased concrete composite beams was suggested on the basis of the above experimental and numerical results.The experiment and analysis results show that the failure mode of a U-section steel-encased concrete composite beam will determine its ductility,and the displacement ductility coefficients of the U-section steel-encased composite beams range from 2.4 to 4.3,being greater than that of a reinforced concrete beam with the same steel usage quantity.

Theoretical Model for Estimation of Cutter Head Torque in Shield Tunneling

GUAN Huisheng, GAO Bo

2008, 21(2): 213-217,226.

[Abstract](1343)

Abstract:
In order to provide a theoretical reference for the design and type selection of shield machines,a theoretical model was proposed based on the systematic analysis of cutter head torque in shield tunneling.Formulae of calculating torque components in this model were deduced,and the validity of these formulae was proven by using an instance to show the correctness of the proposed model.The research results show that in the model,the effects of the shear resistant torque on the back of shield cutter head and the shear resistant torque induced by earth in the hatch of shield cutter head can not be neglected.

Ground Vibration Caused by Moving Metro Trains

HE Zhenxing, ZHAI Wanming, LUO Zhen

2008, 21(2): 218-221,247.

[Abstract](2021)

Abstract:
To study ground vibrations caused by metro trains,a three-dimensional dynamic finite element model was derived with simplifications in tracks,tunnels and loads caused by a running train.A train was composed of 8 cars,and its speed was 80 km/h.The ground vibrations were calculated to analyze the influences of elastic modulus of soils and the burial depth of tunnels.Results show that vertical ground vibrations are generally greater than the lateral vibrations in the area vicinity to the central line of the railway,and decrease rapidly with an increase in the distance to the central line.However lateral vibrations of ground may be greater than vertical vibrations, so they should not be neglected in calculation.Ground vibrations decrease as the soil elastic modulus and the burial depth of tunnels increase.

Stability of Recurrent Cellular Neural Networks with Variable Time Delays

ZHENG Weifan, LONG Lan, ZHANG Jiye, ZHANG Weihua

2008, 21(2): 222-226.

[Abstract](1642)

Abstract:
The global exponential stability of a class of recurrent cellular neural networks with variable time delays was studied using M-matrix theory and vector Lyapunov methods.Without assuming the boundedness,monotonicity,differentiability and Lipschitz continuity of the active functions,an algebraic criterion to ensure existence and globally exponential stability of periodic solutions was obtained.From the weight matrix and damping coefficient matrix of the neural networks,a test matrix was constructed based on the conditions satisfied by the active functions.A recurrent cellular neural network has periodic and globally exponential stable solutions if the test matrix is an M-matrix.

Period-Doubling Bifurcation of Single-Degree-of-Freedom Piecewise-Linearity System with Clearance

XU Huidong, XIE Jianhua

2008, 21(2): 227-231.

[Abstract](1409)

Abstract:
The period-doubling bifurcation and chaos of periodic motions of a single-degree-of-freedom piecewise linear system with clearance was studied.The switching matrix for the system was obtained,and the period-doubling bifurcation of periodic motions was analyzed by the Floquet theory.The poincaré map was established,and the period-doubling bifurcations and chaotic behaviors in the non-smooth system were further investigated by means of numerical simulation.The results show that there is a Floquet multiplier close to-1 for the system,and period-doubling bifurcations occur when the excitation frequency approaches a critical bifurcation point.

LMI Approach for Delay-Dependent Robust Stability of Interval Neutral Systems

YANG Rui, HUANG Tianmin

2008, 21(2): 232-237.

[Abstract](1493)

Abstract:
The LMI(linear matrix inequality) approach was used to solve the difficulty in calculation with the present approaches for the robust stability analysis of a kind of interval neutral systems.A delay-dependent robust stability criterion in the form of LMIs was obtained by defining a new Lyapunov-Krasovskii functional and introducing free weighting matrices to describe the relationships among the terms in the Leibniz-Newton formula.As a result,the robust stability problem for interval neutral systems is transformed into a solvability problem for a class of LMIs.Two numerical examples were given to demonstrate the validity of the proposed approach.

Calculation of Space Electric Field in Railway Container Center Station and Induced Current of Reach Stacker

WANG Jijian, GAO Bo, YE Qiang, WU Guangning

2008, 21(2): 238-241,274.

[Abstract](1670)

Abstract:
The charge simulation method was applied to calculate the space electric field in railway container center stations to investigate the space electric field caused by the catenary and its effects.An ellipsoidal model for a reach stacker was put forward,and induced current of the reach stacker by the space electric field was calculated.The calculational results indicate that the peak value of electric field intensity at a height of 1 500 mm away from the ground is about 1.1 kV/m.When a reach stacker works normally,the induced current is about 0.15 mA,while it is about 0.62 mA when the reach stacker works falsely.The above results show that the induced current is not enough to harm people working at that area under the two conditions.

Propagation Equation and Property of Spectral Degree of Coherence of Partially Coherent Flat-Topped Beams

JI Guangming, GE Hong

2008, 21(2): 242-247.

[Abstract](1189)

Abstract:
Based on the Huygens-Fresnel principle,propagation equation for the spectral degree of coherence of partially coherent flat-topped beams propagating in a free space was derived,and the properties of the spectral degree of coherence were investigated numerically.The research shows that the oscillatory behavior and phase singularities of the spectral degree of coherence may occur.The oscillatory behavior becomes weaker and pairs of points with the phase singularities become fewer with the decreases of beam spatial correlation length and beam order,but the oscillatory behavior becomes stronger and pairs of points with the phase singularities become more with the increase of propagation distance.The width of the spectral degree of coherence becomes larger with the increase of propagation distance,i.e.,the spatial correlation of partially coherent flat-topped beams is improved with the increase of propagation distance.In addition,the relationship between the width of the spectral degree of coherence and the width of intensity is independent of the beam order and propagation distance,but only depends on the spatial correlation length.

New Carrier Recovery Method for 16-QAM Based on Full Constellation Points

WANG Ping, FAN Pingzhi

2008, 21(2): 248-252.

[Abstract](1052)

Abstract:
To improve the carrier recovery performance of 16-ary quadrature amplitude modulation(16-QAM),the relationship between the transmitted data symbol and the signal phase in the constellation was investigated.Based on the relationship,a new carrier recovery method was proposed.In this method,both the diagonal and non-diagonal signal points are used for carrier recovery.The analysis and simulation results show that compared with the traditional carrier recovery methods, the proposed method can provide a wider acquisition bandwidth and smaller phase errors.

ISO/IEC 9126-Based Web Source Quality Assessment System

ZHU Yan, TANG Huijia, MA Yongqiang

2008, 21(2): 253-257.

[Abstract](1452)

Abstract:
An ISO/IEC 9126-based web source quality assessment system was set up to manage the source quality of web-based information systems.This assessment system consists of a multidimensional and multi-tier web quality model,WebQM(web quality model),web source quality evaluation algorithm,and robustness analysis of assessment results.The web source quality modeling and the evaluation using the TOPSIS(technique for order preference by similarity to ideal solution) method were discussed in detail.The robustness analysis was carried out to investigate the effect of the criteria values on the assessment results to improve the WebQM and critical criteria.

Optimal Allocation of Network Resource in IntServ

TAN Xianhai, LI Minghui, JIN Weidong

2008, 21(2): 258-263.

[Abstract](1517)

Abstract:
To improve the effectiveness of resource reservation in network admission control,the implementation method and problem of QoS(quality of service) negotiation and resource reservation of IntServ(integrated services) recommended by IETF(Internet Engineering Task Force) were investigated based on the network calculus theory.Under the conditions of the given arrival curve,maximum delay and buffer size,two new optimal allocation schemes for network resources in IntServ were proposed.The formulas of calculating the desired rate and buffer size for these schemes were derived.The research results show that the proposed schemes can save network resources effectively and raise network utilization through the introduction of a piecewise linear service curve.

Entanglement Degree During Generation of Quantum Controlled-NOT Gates

ZHANG Miao, JIA Huanyu

2008, 21(2): 264-269.

[Abstract](1647)

Abstract:
Generation of quantum controlled-NOT gates consists of sequentially applying three laser pulses to trapped cold ions.The entanglement dynamics during the generation of quantum controlled-NOT gates and the variation in entanglement degrees with time were analyzed.The results show that there is not entanglement between external state and internal state of trapped cold ions in the first and third laser pulses,and there is strong periodic entanglement in the second laser pulse.

Influences of Laser Treatment on Properties of Ni-P Layers Plated on Aluminum Substrates

YANG Yue, YU Chuanying, WANG Jinbo

2008, 21(2): 270-274.

[Abstract](1335)

Abstract:
A Nd-YAG pulsed laser was used to modify electroless plated Ni-P layers on aluminum substrates.The Ni-P layers were successfully modified with a laser power density of 0.515 GW/m2.The modified Ni-P layers exhibit smoother surface,better bonding strength with the substrate,and better corrosion resistance compared with untreated layers.

Numerical Simulation for Solid-State Sintering Processes of Alumina Ceramic Powders

SONG Jiupeng, BARRIERE Thierry, LIU Baosheng, GELIN Jean-Claude

2008, 21(2): 275-279.

[Abstract](1830)

Abstract:
Uniaxial shrinkages and shrinkage rates of alumina powder injection molding components in sintering process were measured by a dilatometer.Based on experimental data,an algorithm for parameter identification was designed to determine the uniaxial viscosity and sintering stresses in the sintering model.Taking the sintering of an alumina hip implant as an example,the sintering model and the identified parameters were introduced into the finite element software,Abaqus,for simulations.The shrinkages and distortions of the components in a sintering process were predicted.The numerical results using the identified parameters agree reasonably with the experimental ones.

Tribological Properties of CrN Coatings Prepared by Physical Vapor Deposition

MO Jiliang, ZHU Minhao

2008, 21(2): 280-284.

[Abstract](1368)

Abstract:
Two kinds of CrN coatings were deposited on cemented carbide substrates by filtered cathodic vacuum arc(FCVA) and multi-arc ion plating(MAIP),and their tribological properties were compared on a CETR UMT-2 tribometer under reciprocating sliding.X-ray diffraction(XRD),micro-hardness and nano-indentation were performed to characterize the coatings.The wear scars of the coatings were evaluated by a surface profilometer,scanning electron microscopy(SEM) and energy dispersive X-ray spectrum(EDX).The wear mechanisms of the coatings were discussed.The CrN coatings prepared by FCVA exhibit smoother,denser and continuous coating surface,and possess higher hardness and much better wear resistance.The different microstructures of the coatings are the main cause of the difference in tribological properties for the two coatings.Combination of abrasive wear and oxidative wear is the sliding wear mechanisms for the two coatings.

Spatial Distribution and Contamination of Heavy Metals in Road Dust,Sediment in Roadside Ditch and Roadside Soils along Zhengzhou-Kaifeng Highway

MA Jianhua, LI Jian

2008, 21(2): 285-291.

[Abstract](1406)

Abstract:
To understand the spatial distribution and contamination of heavy metals along roads and roadsides,Zhengzhou-Kaifeng highway,having operated over 40 a,was chosen as the research object.A sampling transect is perpendicular to the highway.Samples were collected on the line of this transect at a specific interval.The concentrations of Ni,Cu,Zn and Cr in these samples were determined by the flame atomic absorption spectrometry(F-AAS),and Pb and Cd by the graphite furnace atomic absorption spectrometry(GF-AAS).The research results show that heavy metals,except for Ni in road dust,sediment in roadside ditch,and roadside soils along the highway,have accumulated obviously because of trail gas from vehicles,wearing of engine and brakes,and wearing between tires and road surface.The heavy metal concentrations in road dust and roadside soils on the northern side of the highway are higher than those on the southern side.The concentrations of most heavy metals in the road dust are lower than those in the sediments in roadside ditch,but higher than the average values in the control samples and roadside soils within 300 m from the highway.The highest concentrations of most heavy metals,except for Cu in soils,are at 20 to 50 m away from the roadbed, and then gradually decrease to the control values.The incidence of highway traffic exceeds over 300 m from the highway.The zones within 100 m from the roadbed have been moderately or heavily polluted by heavy metals,and Cd,Cr and Pb are the main pollutants originated from the highway.

Fuzzy Comprehensive Evaluation for Green Construction

HUANG Xibing, HUANG Qing, WU Xiaofei

2008, 21(2): 292-296.

[Abstract](1650)

Abstract:
In order to evaluate green construction reasonably,an index system was proposed.This index system is composed of five first-level indexes and seventeen second-level indexes.These first-level indexes include land efficiency,energy efficiency,material efficiency,water efficiency and environmental protection.The second-level indexes include the selection of temporary construction sites and so on.A two-stage fuzzy comprehensive evaluation model was used to evaluate the quality of green construction,and the evaluation conclusion was divided into four ranks.This proposed method has been applied to an actual project in the southwestern China.The evaluation result for the actual project shows that the fuzzy comprehensive evaluation is a feasible method to the evaluation of green construction.

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2008 Vol. 21, No. 2