西南交通大学学报

Driving Effects of Speed Increase on Development of Railway Transportation in China

PENG Qiyuan, WEN Chao, YAN Haifeng

2008, 21(6): 685-691.

[Abstract](1676)

Abstract:
The achievements in the six railway speed increases in China were summarized comprehensively following a review on the speed increases.During the processes of the speed increases,the Chinese railway made great progresses in the following fields.The railway transportation operation mode with the characteristics of high-speed,high-density and heavy-weight was developed on existing lines,and the shortage in railway transportation capacity was relieved.The marketization was accelerated with the diversity of railway transportation products.The centralized transportation dispatching was realized,and a preliminary train operation organization theory system for motor train unit was formed.The progress in freight transportation organization theory for optimization of car flow routing and direct transportation enhanced the transportation capacity.Separation between passenger and freight trains on existing lines established a reference for the operation of high speed passenger railways in China.The development of inter-city passenger transportation strengthed the competitive advantages of railways,and promoted the development of metropolitan economic circles.The advances in railway techniques and application of advanced technologies provided technical supports for the development of railway transportation.

Automation for Offset Plot of Train Flow Lines

CHENG Xueqing, PU Yun

2008, 21(6): 692-696.

[Abstract](1491)

Abstract:
To automatically search key vertexes of train flow lines in a train flow diagram,its components and characteristics were analyzed based on graph theory.An algorithm for searching the key vertexes and that for offset plot of train flow lines were proposed.Train flow diagrams were plotted based on the data in a vertex information table.A database system for automatically plotting train flow diagrams was implemented.An example was presented to indicate the effectiveness and feasibility of the algorithms and software.

Driver Fatigue Detection Based on Unscented Kalman Filter and Eye Tracking

ZHANG Zutao, ZHANG Jiashu

2008, 21(6): 697-702.

[Abstract](1686)

Abstract:
In order to resolve the problem of fast head moving,nonlinear eye tracking and facial fatigue expression detection,a new scheme of driver fatigue detection was proposed based on unscented Kalman filter(UKF) and eye tracking.Owing to the intuition that it is easier to approximate a probability distribution than to approximate an arbitrary nonlinear function or transformation,nonlinear eye tracking can be achieved using unscented transformation(UT) by adopting a set of deterministic sigma points to match the posterior probability density function for eye movement.Driver fatigue can be detected by calculating PERCLOS(percentage of eyelid closure over the pupil over time) under a realistic driving condition after nonlinear eye tracking.The experimental results show that the proposed scheme can not only improve the robustnesses of the head rotating and fast head movement of a driver and the interference of external illuminations,but also provide more accurate estimation than the traditional Kalman filter.

Bi-level Programming for Optimal Inventory Control with Offsetting Replenishment Cycles

GAO Qingping, YAN Qipeng, LIN Yu, LUO Yu

2008, 21(6): 703-708.

[Abstract](1500)

Abstract:
The inventory strategy for multiple products sharing a warehouse in a logistics system was studied.The hypotheses were that the mean total inventory cost consisted of constant ordering cost per order,fixed cost determined by the required warehouse space and variable cost determined by the stored product quantity.The offsets for replenishment cycles of multiple products were used to reduce warehouse space and the relevant cost.The upper and lower programming models are to minimize the mean total inventory cost and necessary inventory spaces,respectively;and their decision variables are the replenishment cycles and the offsets for replenishment cycles,respectively.A particle swarm optimization algorithm was designed to solve the model and calculate the optimal replenishment cycles and offsets.The effectiveness of the model and its algorithm were illustrated with a numerical example.

Investigation on Properties and Mechanism of HPCM Stabilizing Roadbed of Expressway

HE Zhen, WANG Lei, WANG Xuebin, LIANG Wenquan, HUANG Xiaoxia

2008, 21(6): 709-713,746.

[Abstract](1569)

Abstract:
To enhance the stability of soil filled in the roadbed of expressway,a high performance consolidating material(HPCM) was used to improve the stability of primary soil,and its performances such as CBR(California bearing ratio) value,compactness and expansion were investigated through a physical test,SEM(scanning electron microscopy) and XRD(X-ray diffraction) analyses.The research result shows that the CBR value of soil treated by HPCM is increased.Different from conventional approaches to stabilize roadbed,the mechanism of HPCM is to form a tight structure by increasing the combination of soil grains through the interaction of physical and chemical effects to enhance the stability of treated soil.

Maximum Speed Limit on Freeway with Damaged Pavement

CHENG Guozhu, PEI Yulong

2008, 21(6): 714-717.

[Abstract](1524)

Abstract:
A model to correlate passenger uncomfortableness index with vehicle speed,standard deviation of pavement roughness and pavement condition index(PCI) was derived by regression from observed data.Suggestions about maximum speed limits on freeways under different pavement conditions were presented based on the correlation.

Simulated Determination of Accuracy Requirement for Control Points Ⅲ Intersection Networks in High-Speed Railway

LIU Chenglong, YANG Youtao, XU Xiaozuo

2008, 21(6): 718-723.

[Abstract](1310)

Abstract:
To meet the accuracy requirement of relative positioning,it is necessary to perform the further investigation on the form of CPⅢ(control points Ⅲ) control networks and the precision evaluation of observations from field surveying.By combining the standard with the improved forms of CPⅢ control networks,a rigorous method for accuracy estimation based on the parameter adjustment of side-angle measurement network was proposed.A simulated test was performed to investigate the relative accuracy between points,and the necessary precision assessment for field observations was further discussed.The research result shows that the azimuth measurement accuracy of less than ±1″ and the distance measurement accuracy of less than ±(1+1×10-6) mm in a high-speed railway system are respectively required.The research provides a reference for the revision of the present measurement specification for high-speed roadway and the selection of surveying methods for ballastless track.

Conversion of GPS Height Based on Bayesian Regularization BP Neural Network

SONG Lei, HUANG Teng, FANG Jian, ZHOU Xuhua

2008, 21(6): 724-728.

[Abstract](1604)

Abstract:
In order to improve the over-fitting in GPS(global positioning system) height conversion using BP(back propagation) neural network,a new method of GPS height conversion based on the Bayesian regularization BP neural network was proposed.Using the GPS/leveling data in a certain area,this new method was compared with the BP neural network without using the regularization algorithm for GPS height conversion.The research results show that the new method can not only improve the precision of GPS height conversion but also restrain the over-fitting through using the Bayesian regularization algorithm to improve the structure of neural networks in cases with a big area and anomalous height anomaly.The precision of GPS height conversion can achieve 0.050 m to an about 10 km baseline with the new method.

Analysis Method of Dynamic Stability of Suspended-Dome Structures

LUO Yongfeng, LIU Huijuan, HAN Qinghua

2008, 21(6): 729-735.

[Abstract](1455)

Abstract:
Analysis methods of the dynamic stability of suspended-dome structures were discussed.A theoretical investigation was conducted based on the Lypumov dynamic stability theory.The investigation shows that it is difficult to obtain the dynamic instability criterion of a suspended-dome structure under an earthquake with the current methods and the Lypumov theory.Based on the B-R(Budiansky-Roth) criterion,a practical method to judge the dynamic stability was proposed.With this method and time history response curves,the dynamic stability of a suspended-dome structure was judged.Under horizontal,vertical and three-dimensional seismic excitations,the dynamic stability characteristics,stability configuration and cable behavior of suspended-dome structures with different rise-span ratios were analyzed respectively.The results show that under different seismic excitations,the critical dynamic instability configuration is different,and the effects of the rise-span ratio on the dynamic stability are different.The dominant earthquake components of the dynamic instability of the structures with different rise-span ratios are different.When the exciting acceleration approaches the critical point,some cables will relax,but they will be tensioned again during later vibration.

BP Neural Network-Based Prediction of Load-Bearing Capacity of Concrete Column Reinforced by FRP

PAN Yi, YANG Cheng, LIN Yongjun, ZHAO Shichun

2008, 21(6): 736-739.

[Abstract](1645)

Abstract:
In order to enhance the calculation accuracy of concrete columns reinforced by FRP(fiber reinforced polymer) under axial compression,a BP(back propagation) neural network model was established to predict the load-bearing capacity of a concrete column reinforced by FRP under axial compression.The BP neural network model was trained by volume test data,and using the trained model,the load-bearing capacity of concrete columns reinforced by FRP was predicted.A comparison between the predicted and experimental results shows that the BP neural network model can consider more affecting factors and is reliable.Moreover,its maximum error is less than 15%,and its precision is higher than other models.

Calculation of Spanwise Vortex-Induced Vibration Responses of Long-Span Bridge Girder

XIAN Rong, LIAO Haili, LI Mingshui

2008, 21(6): 740-746.

[Abstract](1736)

Abstract:
To provide accurate reference data to vibration restraint,based on the one-dimensional experienced linear VIV(vortex-induced vibration) model the vertical and torsional VIV spanwise responses of a bridge girder were deduced by synthetically considering factors such as mode shape,damping ratio and vortex-induced force correlation.A method was proposed to describe the VIV spanwise responses of a long-span bridge girder.A method to identify the aerodynamic parameters in the experienced linear VIV model through a section model test was discussed.By taking a long-span cable-stayed bridge as an example,the aerodynamic parameters were identified.In addition,the vortex-induced force correlation and the vertical and torsional VIV responses were calculated under different wind attack angles.The research result shows that the response amplitude of VIV influenced by the correlation decreases drastically with the increase of a spanwise distance.

Numerical Analysis of Flow around Two Tandem Circular Cylinders

ZHENG Tinghui, FEI Baoling, YANG Junliu, TANG S K

2008, 21(6): 747-750,798.

[Abstract](1496)

Abstract:
To avoid the sympathetic vibration,the flow around two circular cylinders with an equal diameter in a tandem arrangement was researched numerically using the finite volume method.Strouhal number as a function of spacing ratio and Reynolds number was investigated.The research results show that the behavior of the Strouhal number with change of the spacing ratio is decided by flow regions,and the effect of the Reynolds number on the Strouhal number has the same trend in all flow regions.The Strouhal number increases with the Reynolds number increasing,but there is a great difference in the increasing amplitude to different flow regions.

Numerical Simulation of Starting Process of Supersonic Pulse Wind Tunnel

ZHANG Xiaoqing, LE Jialing, XU Mingheng

2008, 21(6): 751-755.

[Abstract](1383)

Abstract:
To analyze the transmitting process of incident shock and the transient flows,the starting process was simulated numerically.In the simulation,the control equations were the conservational Navier-Stokes equations with a species diffusion term,which describe two-dimensional viscous,compressible and unsteady flows.The cell-centered finite volume scheme was used for space discretization,and the dual-time stepping method was taken to calculate the unsteady term.The calculated results reasonably agreed with the experimental ones.The research shows that during the starting process,the velocity of incident shock changes due to the variation in inner profile,and gets its maximum at the isolator.

Simulation Research on Fuzzy Shift Strategy of Automobile

WU Shijing, ZHU Enyong, LI Qunli, WANG Xiaosun

2008, 21(6): 756-761.

[Abstract](1601)

Abstract:
In order to avoid shift cycle in the process of fuzzy control for automatic transmission shift,a new fuzzy control strategy was designed.A shift map obtained from an experiment was divided into an upshifting map and a downshifting map,and two corresponding fuzzy controllers,upshifting controller and downshifting controller,were designed.It was put forward that the controllers should work in the light of the acceleration,i.e.,the system is controlled by the upshifting controller when the acceleration is positive,and it is controlled by the downshifting controller when the acceleration is negative or zero.A simulation model was built to achieve the control strategy,and a simulation was carried out to validate the correctness and feasibility of the fuzzy shift strategy designed.The simulation result shows that an automobile with this shift strategy can effectively avoid shift cycle even if it is running in a complicated driving condition and this shift strategy can obtain the optimal power and economic performances.

Self-Excited Torsional Vibrations of Drive System of Locomotive under Slippage

YAO Yuan, ZHANG Hongjun, CHEN Kang, JIN Dingchang

2008, 21(6): 762-766.

[Abstract](1703)

Abstract:
A simplified model for torsional vibrations of a single wheel-set drive system was used to study torsional vibrations of a locomotive under slippage.In the model,torsional stiffness of the shaft of a wheel set and that between the traction motor and the wheel-set were taken into account.The phase trajectories of the torsional vibrations are a set of stable limit cycles,signifying self-excited vibrations when the average wheel-rail creepage is over the critical value.Frequencies of torsional vibrations with different operating modes were calculated.The results show that the vibration frequency is in accordance with the natural frequency of the drive system when self-excited vibrations happen.Therefore,analyzing the vibration frequency of wheel-sets is a measure to identify wheel-rail slippage.

Adaptive Control of Humanoid Robot Movement

DENG Xingqiao, WANG Jinge, FANG Chun, ZHU Weibing

2008, 21(6): 767-771.

[Abstract](1528)

Abstract:
The dynamic and kinematic formulas were derived based on Danevit-Hartenberg coordinate transformation,and the generalized Jacobian matrix was obtained.An adaptive controller was designed to ensure the asymptotic stability of the robot system.Simulated snapshots and joint trajectories of a dancing humanoid robot were presented.The simulation results verified feasibility and effectiveness of the controller.

Efficient Computation of Space-Time Finite Element Method

LI Tian, ZHANG Jiye, ZHANG Weihua

2008, 21(6): 772-777.

[Abstract](1709)

Abstract:
To improve the computational efficiency and reduce the requirement on memory in solving two-dimensional transient incompressible Navier-Stokes equations with space-time finite method,the compressed sparse row format was used to store the large-scale sparse matrix,Newton-Raphson method was adopted to solve the nonlinear equations and the restarted GMRES method with the zero fill-in incomplete triangle decomposition precondition was adopted to solve the linear equations during sub-iterations.To verify the feasibility of the proposed method,the problem of flow around a circular cylinder was numerically simulated at the Reynolds of 100.The required memory with the compressed sparse row format was 3.68% of that with equi-band-width storage method.

Simulation of Turbo Code System Based on Simulink

ZHONG Xiaochun, HAN Jiajia, LIANG Nawei

2008, 21(6): 778-781.

[Abstract](1419)

Abstract:
Based on the theory and architecture of Turbo coding and decoding,a model of Turbo code simulation for controllable coding/decoding was designed with software Matlab/Simulink and used in the system with BPSK(binary phase-shift keying) modulation in AWGN(additive white Gaussian noise) channel.An investigation into BER(bit error rate) of the Turbo coding/decoding system and two conventional systems shows that compared with the two conventional systems,BER of the developed Turbo coding system decreases by one order of magnitude,and this advantage is even more obvious in the case of low signal-noise ratio.

Design of X-Band 4-Element Square Helical Array Antenna Fed from Radial Line

ZHAO Liu, LIU Qingxiang, CHEN Xiaobo, LI Xiangqiang

2008, 21(6): 788-792.

[Abstract](1814)

Abstract:
To probe into the approach of array antenna with high power and high gain,a square helical array antenna fed from a radial line was proposed and designed,and its fundamental principle was presented.The radiation element,the coupling probe and the feeding system were designed in details,as a result,an X-band 4-element array model was obtained.The numerical simulation result of the array model shows that in the range of 8.5 to 10.3 GHz,the antenna reflectance is below 0.1,the antenna gain is over 12 dB,and the antenna axial ratio is below 1.9.

Fuzzy Assessment of Web Resource Quality

ZHU Yan

2008, 21(6): 793-798.

[Abstract](1376)

Abstract:
To integrate high quality Web resources and improve the performance of a Web information system,fuzzy logic and multi-criteria decision making(MCDM) methods were investigated.FTOPSIS method,integrated by the fuzzy logic technique and the TOPSIS(technique for order preference by similarity to ideal solution),was used to deal with the incompleteness,imprecision,uncertainty and subjectivity in Web quality quantization and assessment.The assessment principle was discussed,and the complete procedure of Web quality assessment was described through an example.In addition,the sensitivity analysis of assessment results was carried out.The assessment method discussed can better quantize Web resource quality in a fuzzy environment and improve the assessment procedure so as to obtain more precise results.

Fragile Watermarking Scheme with Abilities of Self-restoration and Discrimination of Tampers on Image Content or Watermark

FAN Mingquan, WANG Hongxia

2008, 21(6): 799-805.

[Abstract](1578)

Abstract:
Based on the fact that the current fragile watermarking scheme with the ability of tamper discrimination can not discriminate tampers effectively,a novel fragile watermarking scheme with the abilities of self-restoration and discrimination of tampers on image content or watermark was proposed.In this scheme,the authentication watermark is used to localize and discriminate tampers,and the resumptive watermark is utilized to resume the tampered image content.Theoretical analysis and experimental simulation show that the proposed scheme has good abilities of tamper discrimination,tamper localization and tamper restoring,even more the ability of resisting synchronization counterfeit attack and key analysis attack.

Field Emission and Photoluminescence Properties of Al-Doped T-ZnO Whiskers

FAN Ximei, ZHOU Zuowan, LI Yanxia, ZHANG Huiguang

2008, 21(6): 806-809,815.

[Abstract](1167)

Abstract:
Al-doped tetrapod-like ZnO(T-ZnO) films were fabricated using screen printing method to study their structures,surface morphologies,optical properties and field emission behaviors.All samples show typical photo luminescence(PL) behaviors with two emissions of a narrow UV peak centering around 373 to 383 nm and a green deep level peak centering around 510 to 540 nm.The green deep level PL emission is attributed to the defects in the T-ZnO films.The largest UV peak and the highest field emission were observed on 0.5 mol/L Al-doped T-ZnO films.The turn-on field and the threshold field of the T-ZnO films were 3.6 V/μm and 6.9 V/μm,respectively,and the enhance field factor was 30 249.

Experimental Investigation on Aerated Concrete with Addition of Lead-Zinc Tailings

LI Fangxian, CHEN Youzhi, LONG Shizong

2008, 21(6): 810-815.

[Abstract](1498)

Abstract:
Lead-zinc tailings were used to produce aerated concrete.The effects of water-binder ratio,casting temperature and aluminum powder content on the gas forming behavior,and those of lead-zinc tailing content,cement content and conditioning agents on the compressive strength of the aerated concrete were investigated.Optimal raw material formulation and procedure were determined for the aerated concrete.The compressive strength and frost resistance of the aerated concrete made by the optimal raw material formulation and procedure conform with the requirements of aerated concretes of B06 grade,and thermal conductivity,drying shrinkage and radioactivity conform with the relevant national standards of China.

Key Techniques of Information System Construction for Non-stable Multi-model Logistics Enterprises

ZHANG Xueyan, CHEN Ning

2008, 21(6): 816-821.

[Abstract](1492)

Abstract:
Businesses of logistics enterprises in transformation are in multi-mode and complicated.The information system for these enterprises should be constructed based on two aspects: process integration and information system architecture optimization to assure its adjustability and expansibility.An optimization method was proposed,which include business process standardization,sub-process normalization and configurable core processes;and a system architecture was presented,which was characterized by SOA(service oriented architecture),EDI(electronic data interchange) and proper hierarchy classification.The proposed method and the system architecture were verified by a case study.

Weak Target Detection of Passive Radar in Strong Jamming Environment

LIU Zhiqiang, MA Hongguang, YANG Lifeng

2008, 21(6): 782-787.

[Abstract](1003)

Abstract:
It is difficult for a passive radar to detect weak targets under the background of strong jamming coming from large targets,near air fleet or deception jam.Based on the connection between strong and reference signals,the relationship between the amplitude-range-Doppler surface and the ambiguity function of the reference signal was deduced,and a detection method for weak targets was proposed based on two-dimension FIR(finite impulse response) system identification.Simulation results indicate that the proposed method can restrain the strong signal beyond 60 dB,and even to weak targets with an echo SNR(signal to noise ratio) of-24 dB,they can be detected.

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2008 Vol. 21, No. 6