西南交通大学学报

Study on the Distribution Patterns of Time Headway of Vehicles

LUOXia, DUJin-you, HUO Ya-min

2001, 14(2): 113-116.

[Abstract](1550)

Abstract:
Taken mixed traffic flows as the basic constitution of high ways, the combinatorial probability of following sequences of mixed traffic flows is analyzed. The relationship between vehicle speeds and the maximumtime headway and that between the minimum time headway and randomness of traffic flows are obtained. Then the macro-parameters are integrated with the micro-parameters through randomness of traffic flows.

Network Flow Models for Organization of Transship Trains in Railway Terminals

YAN Yu-song, ZHUSong-nian, DUWen

2001, 14(2): 117-120.

[Abstract](1498)

Abstract:
Accordingto the basic properties of network flows and the analysis of the organization of transship trains in railway terminals, a method to construct the model for the organization of the transship trains is proposed. The organization problem is converted to an optimization problem of point, arc and point-arc transformation of network flows. The general procedures to get the solution to the model are presented.

An Application of Calculation of Corridor OD Flows

SHUAIBin, QINGXue-jiang, HUO Ya-min

2001, 14(2): 121-125.

[Abstract](1233)

Abstract:
Traffic flow investigation is an important step in the traffic planning. In this paper, the relationship between corridor OD flows and section flows is analyzed, and a method is proposed to calculate corridor OD flows via road section flows. The procedures to divide bi-directional flows into two single directional flows are discussed. The formulae for OD flow calculation are derived.

Analysis and Application of RF Transmission in Electric Railway Tunnels

WEI Yong-an

2001, 14(2): 126-130.

[Abstract](1455)

Abstract:
RF transmission in electric railway tunnels is studied based on the characteristics of the tunnel walls and the fact that there are catenary and rails as paths of signals. The RF frequency, its propagation mode and the calculation of the electric field are analyzed. As an example, application of the radio transmitters designed for communication in a mountainous section in Baoji-Chengdu railway is presented. It is shown that an electrified railway tunnel is an effective channel for transmission of language and slow digital signals.

A Mobile-Location Based Dynamic positioning Algorithm

DengPing, Fan Pingzhi

2001, 14(2): 131-135.

[Abstract](1380)

Abstract:
In this paper,a mobile location-based dynamic positioning algorithm is proposed based on measured time of arrival(TOA). This algorithm can be used in cellular networks to estimate mobile location from mobile radio TOA information detected by several base stations(BS). The BS numbers and the corresponding weights utilized in this algorithm can be dynamically adjusted according to the distance between mobile station(MS) and serving BS. Location estimate can also be made if onlyTOA and angle of arrival(AOA) are measured by serving BS. Therefore, this algorithm could be applied to many mobile communication channel environments. Simulation results showthatthe location performance of this algorithm is satisfactory in three typical mobile communication channels.

Analysis on the Characteristics of Generalized Congruence Neural Networks with an Improved Algorithm

HUFei, JINFan

2001, 14(2): 136-139.

[Abstract](1544)

Abstract:
An improved learning algorithm for GCNN is proposed and presented in this paper based on a study on the characteristics of GCNN. In addition, a comparison between GCNN and the currentwide used BP net algorithms is performed. Computer simulation using concrete examples shows that the suggested algorithm provides satisfied fitting features and faster learning speed.

Modeling and Simulation of Three-Phase Asynchronous Motors

GENG Biao, XIEHong-ji, RENGuang

2001, 14(2): 140-143.

[Abstract](1482)

Abstract:
Amodel forthree-phase asynchronousmotors, which is in a static coordinate system, is proposed to develop a vector control system for three-phase asynchronous motors. The hardware and software of the simulating system are discussed in detail. The parameters of an actual motor are taken for the simulation with the simulating system. The exactness and practicality are verified by comparingthe results of simulation and those of experiments.

Dynamic Characteristics of Gantry Cranes with an Elastic Trolley Frame

CHENG Wen-ming, DENG Bin, WANGJin-nuo

2001, 14(2): 144-148.

[Abstract](1330)

Abstract:
Unlike conventional dynamic calculation inwhich rigid models are used, a serial elastic model of three masses and three degree of freedoms for the trolley frame of container gantry cranes is proposed by taking the large span of the trolley beam into consideration. The precise solutions to the vibrating equations are obtained byusingmodal analysis. The results showthatthe dynamic coefficients ofthe trolleyframe, the gantry structures and the wirerope-pulley system are different

Experimental Research on Dynamic Characteristics and Coupled Vibration of a Maglev Train System

TANGHuai-ping, GAO Fang-qing

2001, 14(2): 149-152.

[Abstract](1543)

Abstract:
In this paper, the results of dynamic test conducted on a scaled model of a maglev train system are presented. The resonant characteristics of the sub-structures of the maglev train system, the structural dynamic responses at levitated and running state, coherence of the levitated train body, the variation of the air gaps between the magnets and tracks, and the coupled vibration ofthe sub-structures are analyzed. Some methods to lower and control the structural dynamic responses and the coupled vibration of maglev systems are putworword

A Study on Dynamic Characteristics of Vibrators in Concrete Stirring Bars

SHENHuo-ming, GAO Shu-ying, SHUBin

2001, 14(2): 153-156.

[Abstract](1311)

Abstract:
Amechanical model for concrete stirring bars is proposed and its fourth-order partial differential equation is derived. The bars are idealized to free-free beams with lumped mass. The corresponding frequency equation is also derived from the solutions to the differential equation, the boundary conditions and continuous condition at the lumped mass. The dynamic characteristics of the stirring bars are obtained. The relationship among the position and eccentric distance of the vibrator, the dimension of the stirring bar and the vibrating frequency is discussed.

Finite Element Analysis for Shape Memory Alloys

LIUAi-rong, PAN Yi-su, ZHOUBen-kuan

2001, 14(2): 157-151.

[Abstract](1610)

Abstract:
Based on an existing constitutive model of shape memory alloys, a formulation of incremental finite element is derived and the calculation is done on a computer. Numerical examples of a rod and an infinite panel with a circular hole, both under uniaxial tension, are analyzed with the derived formulation and tested. It is shown that the numerical results are in agreement with the experimental results. Finally deformation of a shape memory cantilever beam caused by temperature change is simulated.

Mapped Infinite Element for Three-Dimensional Intercalations

SUGuo-shao, DUANHai-juan, YANLiu-bin

2001, 14(2): 162-165.

[Abstract](1159)

Abstract:
A model and its formula of 3-D 10-node mapped infinite element for intercalations in rock engineering are proposed. In comparison with the ordinary finite element simulation, with this model the time for data preparation and CPU time are effectively reduced, and higher computational accuracy is achieved by taking a smaller area into consideration. This model also features clear concept, simple programming and suitable for computation on PCs.

Research on Prediction of Noises of High Speed Railway Bridge

WANG Zhong-shi, WANG Feng-qin, GAO Shu-ying

2001, 14(2): 166-168.

[Abstract](1693)

Abstract:
In this paper, the statistical energy analysis (SEA) is applied to prediction of the noises of high speed railway bridges. Based on analysis on the relationship between the principle of SEA and production of noises of high speed railwaybridges, SEA is considered as a feasible method for predictingnoise radiation of high speed railway bridges. Amathematical model of energy exchange among the sub-structures of railway bridges is proposed by using SEA.

Analysis on Dynamic Loads on Ballast of Shenzhen Subway

LI Cheng-hui, YUJin-jiang, QIUWen-ge

2001, 14(2): 169-171.

[Abstract](1871)

Abstract:
According to the model of coupled vibration of vehicle and tracks, the dynamic loads of ballastof Shenzhen subway are calculated in both frequency and time domains. The relationship between dynamic loads and track irregularitywavelengths are obtained. The maximumdynamic load is about80 kN/mmatthe worst frequency, about 62 Hz

An Elastic-Plastic Finite Element Analysis on Tunnel Structures at Cycled Temperatures

ZUO De-yuan, ZHENGAn-qi

2001, 14(2): 172-175.

[Abstract](1612)

Abstract:
An analysis is conducted The excavation and lining of a tunnel structure are analyzed with numerical calculation. Then, according to the principle of unstable heat transfer, the properties of local concrete linings of the tunnel in the condition of cycled temperatures are studiedwith elastic-plastic hybrid/ mixed finite element method. The results show that at natural temperatures, the stresses in the tunnel structure are evenly distributed. On the other hand, the cycled temperature may cause the surfaces of the linings to become plastic and pill off if unattended.

Geogrid-and Geocell-Reinforced Sand Blanket: Model Test and the Ability to Reduce Deformation

SUQian, CAI Ying

2001, 14(2): 176-180.

[Abstract](1554)

Abstract:
In this paper, amodel teston soft subsoil confinedwith sand blankets reinforced bygeogrids and geocells is presented. The ability to resist deformation of the subsoil is discussed in detail. The sand blankets distribute the load effectively, so that the value ofK30is remarkably increased by over 57% and the deformation of foundation is decreased by about 40%.

Analysis on the Effect of Stresses on Corrosion of Reinforcing Steels

DANDan-hui, HE Guang-han

2001, 14(2): 181-184.

[Abstract](1511)

Abstract:
In accordance with the corrosive dynamics of reinforced concrete and chemico-mechanical principles of metallic corrosion, the influence of stresses in reinforcing steels on corrosive reaction velocity under the condition that there is no crack in the concrete is analyzed. It is confirmed by calculation that, under the condition of uniformcorrosion, stresses in reinforcingsteels do nothave notable effecton corrosion rate of the reinforcing steels.

A Model Test on the Anchorage Zones of the Second Nanjing Changjiang River Bridge

CHENWei-qing, ZHANG Qiang

2001, 14(2): 185-189.

[Abstract](1733)

Abstract:
Amodel teston the anchorage-boxof the SecondNanjing ChangjiangRiver Bridgewas conducted at the Center of Structural Engineering Experiment of Southwest Jiaotong Universiy. The safety of and the detailed stress distribution in this structure, and the reliability of the connection between the anchorage-box and webs are investigated. The test results are practically in agreement with those of FEM calculation and are recommended as references for designs of similar structures.

Feasibility of Directly Utilizing GPS Baseline Vectors in Local Engineering Networks

GONGTao

2001, 14(2): 190-194.

[Abstract](1290)

Abstract:
Due tothe difference betweenWGS-84 and local ornational reference systems, such as BJ-54 (Beijing System of 1954), coordinate transformation is necessary before GPS results are utilized for local engineering control. However, the transformation depends on the accurate national geodetic control points that are usually not enough or not available at all in an engineering field. The feasibility to directly utilize the GPS baseline vectors as the distances on the BJ-54 coordinate without coordinate transformation is proved by computation analysis conducted through out China. The principles to determine the proper baseline vectors are studied and presented in detail.

A Study on Buffering Analysis of GPS in Map Matching Applications

WUXu-yan, LUO De-an

2001, 14(2): 195-198.

[Abstract](1366)

Abstract:
GPS and GIS arewidely used in vehicle control and navigation systems. Both of them, however, have system and random errors that can lead a vehicle navigation system to failure. Fortunately, map matching technique can create a bridge between GIS and GPS to prevent the failure to some extent. However, it is difficult for the available methods to deal with the errors in real-time. Based on a study on the map matching technique, the buffering analysis method that has been used in GIS is utilized to correct the errors introduced by every sources and realize the map matching. This method has been put into application and its feasibility and effectiveness have been proved in vehicle navigation systems.

Losses of Bessel-Gaussian Beams Propagating through a Hard-Edge Aperture

WANGLi

2001, 14(2): 199-201.

[Abstract](835)

Abstract:
The losses Bessel-Gaussian beams, a kind of non-diffracting beam, propagating through a hard aperture are studied, and ageneral formula is derived. As an example of applications, numerical calculation is performed to calculate the losses of Bessel-Gaussian beams propagating through a circular aperture. The obtained results are analyzed and discussed. The proposed method can also be applied to calculation of the losses of other types of laser beams propagating through a hard-edge aperture.

Single Toroidal Non-Reciprocal Ferrite Phase Shifters

FENG Quan-yuan, RENLang

2001, 14(2): 202-205.

[Abstract](1111)

Abstract:
The single toroidal non-reciprocal ferrite phase shifterthat is the key components of a phase array antenna is studied to develop the phase array antenna for autotracking synchronous communication satellite. The transcendental equation for the single toroidal non-reciprocal ferrite phase shifter is obtained by using the twin slab model, and its properties are discussed. The differential phase shift changes as the change in the thickness of the ferrite phase shifter is calculatedwith the transcendental equation. The results showthat the differential phase shift increases with the increase in the thickness of the ferrite slab and the increase becomes gradual when the thickness increases to certain values.

Self Organizing Methods and a Model Study on the Growth of West China’s GDP

KANG Yin-lao, YANKe-qi

2001, 14(2): 206-210.

[Abstract](1443)

Abstract:
On the basis of the theory of self organizing cybernetics, a new data mining method is proposed by using the principles of artificial neural networks. During modeling, active neurons are generated and eliminated largely, enabling the model to evolve into its optimal complex. Some principles, processes and network structures of self-organizationmethod are discussed. As an example, the economy in thewest China is studied with the model to find the critical factors. Some suggestions about the development of the west China are put forward.

A Heuristic Genetic Algorithm for the Travelling Salesman Problem with Time Restraints

XIEBing-lei, LIJun, LIUJian-xin

2001, 14(2): 211-213.

[Abstract](1447)

Abstract:
As an extension of the travelling salesman problem, the travelling salesman problem with time windows is a very difficult problemwith great theoretical and practical significance. In this paper, the time restraints are converted intoobjective restraints, and genetic algorithmswithmutations by2-exchange and by 3-exchange, respectively, are designed by using sequence coding to deal with the soft and hard time restraints. The simulation indicates that the latter algorithm is superior to the former, and that both of the proposed algorithms are superior to the simple genetic algorithm.

Analysis on the Chaotic Motions of Some Nonlinear Dynamic Systems

YEJian-jun, CHENQiu

2001, 14(2): 214-216.

[Abstract](1323)

Abstract:
The conditions for chaotic motions of some dynamical systems with nonlinear structures are studied in this paper. The relationship between existence of Smale horseshoes and mechanical system parameters is obtained by applying the Melnikov analytical method.

Notes on the Factorizations of Compact and Weakly Compact Operators

JIN Yu-guang, CHENZi-li

2001, 14(2): 217-219.

[Abstract](1228)

Abstract:
This work is devoted to the factorization problems for compact and weakly compact operators between Banach lattices. Under the same known conditions, a more symmetric formof factorization theorem is approved for compact and weakly compact operators between Banach lattices through reflexive Banach lattices.

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2001 Vol. 14, No. 2