西南交通大学学报

Some Remarks on Lattice Implication Algebra

QIN Ke-yun, CHEN Zhi-guo

2003, 16(1): 1-3.

[Abstract](1447)

Abstract:
A sufficient and necessary consition for a general (2,1,0,0) type algebra (L,→,*,0,1) to be a lattice implication algebra is presented. It is proved that in a finite chain and in a non-linear four-element lattice there exists only one lattice implication algebra, but no implication algebra in a non-linear five-element lattice. This provides the foundation for further study of the structure of lattice implication algebra that is composed of linguistic true values.

The Simplicity and Periodicity of Lattice Implication Algebra

WANG Xue-fang, XU Yang, SONG Zhen-ming

2003, 16(1): 4-7.

[Abstract](1256)

Abstract:
The simplicity and periodicity of lattice implication algebra are discussed, and their relationship is studied. Several methods to determine the simplicity of a lattice implication algebra are presented. An important conclusion is that there is a unique dual atom in a finite simple lattice implication algebra whenever it has a dual atom.

Solving Multi-objective Programming Problems with Maximal Entropy Method and Genetic Algorithm

LIUHai-yan, CHEN Gao-bo, PENG Chuan

2003, 16(1): 8-11.

[Abstract](1446)

Abstract:
The maximal entropy method is applied to convert a non-differentiable multi-objective programming to a differentiable one. Then the converted multi-objective programming is solved with genetic algorithm because of the high nonlinearity of its objective functions and restraints. A typical example from literature is solved as an example, with satisfactory accuracy obtained.

Computation of Stress Power Density Spectra of Components in a Random Vibration System

PAN Wu-ming, YANG Ming-ju, XU Yang

2003, 16(1): 12-16.

[Abstract](1557)

Abstract:
The key to analyzing the fatigue life of a random vibration system is to determine its stress power density spectra (SPDS) at the fatigable position of load bearing components. A method called unit stress matrix method is proposed in this paper to calculate the SPDS of non-self-vibration components in a random vibration system. The existence of the unit stress matrix is discussed. An example is presented to show the effectiveness of the proposed method and the procedure of calculation.

Simulation of Lateral Dynamic Performances of Locomotives and Vehicles—Comparison of Vehicle/Track Coupling Model with Traditional Vehicle Model

WANG Kai-yun, ZHAI Wan-ming, CAI Cheng-biao

2003, 16(1): 17-21.

[Abstract](1666)

Abstract:
The lateral dynamic performances of vehicles are calculated with the vehicle/track coupling model and the traditional vehicle model to investigate the differences. The software TTISIM that has been verified by many field experiment results is used for the calculation. The results show that the lateral wheel/rail forces obtained with the traditional model are higher than those with the vehicle/track coupling model when vehicles running on tangent, curved tracks or turnouts, that the critical speed of hunting stability based on the vehicle/track theory is lower than that based on the traditional theory, and that there is not obvious difference in vertical and lateral vibrations determined with the two models.

Analysis of Vehicle-Track Coupling Vibration Based on Timoshenko Beam Model

XUZhi-sheng, ZHAI Wan-ming, WANG Kai-yun

2003, 16(1): 22-27.

[Abstract](1628)

Abstract:
Based on the theory of vehicle-track coupling dynamics, a model of vehicle-track coupling vibration is established, in which a rail is assumed to be a Timoshenko beam resting on the discrete sleepers. The natural vibrations of tracks are analyzed, and dynamic responses between vehicle and track caused by track irregularity are also preliminarily investigated. The characteristics of the natural vibration and forced vibration of the Timoshenko beam model are different from those of Bernoulli-Euler beam model. It is shown that the Timoshenko beam model is more applicable to describing the high-frequency vibration of rails.

Hunting Stability and Riding Quality of Four-Axle Power Cars with Motor Mounted on Frame

CHEN Kang, LUO Yun, JIN Ding-chang

2003, 16(1): 28-33.

[Abstract](1605)

Abstract:
IDetailed calculations have been made on the dynamics of four-axle pwoer cars with motor mounted on frame. The numerical results show that the frame masses between the primary and the secondary suspensions influence the riding quality greatly. It is very important to set an appropriate secondary lateral stop clearance, and the influences of damping of the secondary suspension to the riding quality is related to the stiffness of the secondary suspension. It is also necessary for the parameters of yaw dampers to match those of lateral dampers to achieve good hunting stability.

Analysis of Wheel/Rail Contact Stresses and Rail Corrugation

ZHANG Li-min

2003, 16(1): 34-37.

[Abstract](1505)

Abstract:
Numerical analysis is conducted with a material-strengthening model to study the residual stresses and accumulated deformation in rails by taking the accumulation effect of plastic deformation and ratcheting effect of rail materials into consideration. The results show that the ratcheting effect of the rail material and the fluctuation of wheel/track contact forces are important factors to initiate stripping of the rail surfaces and short wave corrugation.

Dynamic Responses of Overlapping Tunnels to Passing Trains

GAO Feng, GUAN Bao-shu, QIU Wen-ge, WANG Ming-nian, LI Cheng-hui

2003, 16(1): 38-42.

[Abstract](1759)

Abstract:
The phase I of Shenzhen subway project was taken as the background of this study. The vibration loads caused by passing trains are obtained with a wheel/track model available in literature. The initial stresses of after excavation are calculated with stress relaxation method. The rational time step and damping of vibration analysis are defined by vibration modes and frequencies obtained with modal analysis. The dynamic responses of overlapping subway tunnels to the vibrations caused by trains running from either directions (namely up and down directions) and vis- a-vis are studied with Newmark implicit time integration method. The stresses, displacements and weak portions in the liner are determined under the vibration loads.

Lateral Stability of Parabolic Double-Rib Arch Under Directional Loads

YANG Yong-qing

2003, 16(1): 43-48.

[Abstract](1670)

Abstract:
A parameterized calculation method is proposed to calculate lateral stability of parabolic double-rib arches under directional loads. The influences of structural parameters on the lateral stability of arches are analyzed. The calculation results show that the critical load of double-rib arch is twice or three times as the bearing capacity obtained by experiment.

An Improved Pseudo Variable Algorithm for Structural Reliability

ZHANG Xin-pei, CHEN Ying

2003, 16(1): 49-52.

[Abstract](1570)

Abstract:
The conventional pseudo variable algorithm can not be used for structural functions consisting of dependent random variables and of high nonlinearity. An improved pseudo variable algorithm for calculating structural reliability is proposed to solve the problem. The calculation results of an example show that the improved algorithm overcomes the shortcomings of the conventional pseudo variable algorithm and is suitable for structural functions with high nonlinearity and dependent random variable

Three-Dimensional Seismic Responses of Long-Span CFST Arch Bridge

ZHENG Jia-shu, JIN Bang-yuan

2003, 16(1): 53-56.

[Abstract](1656)

Abstract:
A long-span concrete filled steel tube (CFST) arch bridge, Longtan river bridge, is simplified into a space FEM model to calculate the dynamic responses to seismic an input. In the model, the boundaries between the foundations and the structure are considered to be connected with springs. The natural vibration frequencies are calculated with a space iteration program compiled by the authors, and three-dimensional geometric non-linear seismic responses are analyzed with Wilson-θmethod. Calculating results show that the interaction between founders and the structure influences frequencies of all orders considered, axial forces and moments, and mid-span displacements.

Selection of Positions for Yesan River Bridge Foundations in Yichang-Wanzhou Railway

ZHAO Wen, XIE Qiang

2003, 16(1): 57-59.

[Abstract](1745)

Abstract:
Based on the natural stable angles on the banks of Yesan river determined with an empirical formula, bridge foundation sites are selected preliminarily. Then the maximum principal stress of the slope rock is simulated under loading of the foundations at different positions, the influencing ranges of stresses are analyzed, and the rock mass strength of the slopes is analyzed by use of Mohr strength theory. Finally, the rational positions of the bridge foundations are determined.

Operation and Maintenance Modes of Qinghai-Tibet Railway

LUXiang-rong, WANG Qi-rong, GAO Ping-ping

2003, 16(1): 60-63.

[Abstract](1447)

Abstract:
In order to guarantee safe and stable operation of Qinghai-Tibet railway, it is required to seek operation and maintenance modes and safety measures suitable to Qinghai-Tibet plateau. Based on the current modes and specialty of Qinghai-Tibet railway, operation and maintenance modes and the development tendency during operation of Qinghai-Tibet railway in the future are analyzed. Finally, the authors put forward the reasonable operation and maintenance modes and safety measures.

Safety Design of Impervious Liner of Solid Waste Landfill

LI Qi-bin, LIU Dan, YANG Li-zhong

2003, 16(1): 64-69.

[Abstract](1345)

Abstract:
The permeability and filtration capacity of liners and capacity of a landfill site are investigated to design safe impervious liners of solid waste landfill. The permeability of the main pollutant, Cl-, of a solid waste landfill is obtained with soil column test. The capacity of the landfill site is determined by taking geological and hydrogeological properties of the site. It is shown that the water head of leachate on the impervious layer affects greatly the total amount of pollutants infiltrating to underground water. A design of impervious layers for the solid landfill is presented as an example.

Coefficient of Passenger Train Removal on Double Track Railway with Automatic Block System

MA Si, NI Shao-quan, ZHAN Wen-hua

2003, 16(1): 70-74.

[Abstract](1738)

Abstract:
Based on the analysis on optimal overtaking scheme for a single passenger train and calculation of minimum coefficient of passenger train removal, different passenger trains are categorized according their intervals on a train diagram. A method for determining the optimal overtaking scheme and an algorithm for calculating the coefficient of removal are proposed for multiple passenger trains with influence sections intercrossing on train diagram. The formula for calculating the coefficient of passenger train removal with given passenger train scheme is presented. The accuracy of calculation is verified with an example.

Study on Combined Models of Demand Forecasting for Urban Traffic

YUXiang, MAO Min, LIUJian-bing

2003, 16(1): 75-79.

[Abstract](1368)

Abstract:
The application of combined models for traffic demand forecasting is analyzed, and emphasis is put on two combined models applied to demand forecasting for urban traffic. An example of combined model for trip distribution and assignment based on the principle of entropy maximization is presented. A model of generalized trip cost for all types of urban passenger traffic modes is proposed. Then a combined model for trip mode categorizing and assignment is put forward based on the principle of generalized trip cost and dynamic probability assignment.

Shortest Path Searching Based on City Road Database

WU Bi-jun, LI Li-xin, LEI Xiao-ping

2003, 16(1): 80-83.

[Abstract](1510)

Abstract:
In intelligent traffic navigation or dynamic path abduction systems, the shortest path searching is the basic function. According to the nature of road net of a city, the database structure describing the city road net is studied. Based on the database structure and the need of a GIS system, the road information is collected. Then Dijkstra algorithm is used to realize fast searching of the shortest path. The electronic map of Guangzhou is presented to show an example of city raod searching, the time of a shortest path searching result, which includes 61 crossings, being about 2.2 s.

A Capacity-Enhancing Plan for the Cangbomen to Jiangning Section in Nanjing-Wuhu Railway

JIANG Wei-ping

2003, 16(1): 84-86.

[Abstract](1579)

Abstract:
Several capacity-enhancing plans for the Cangbomen to Jangning section in Nanjing- Wuhu railway are analyzed. A new plan is suggested. The existing railway within the urban area of Nanjing will be converted to a light rail transit system and transferred to Nanjing government. As an exchange, the government provides the railway authority with favorable policies and invests some capital for building a new double-track railway in the suburb. This plan will be beneficial to the both sides.

Immune Evolutionary Algorithm

NI Chang-jian, DING Jing, LI Zuo-yong

2003, 16(1): 87-91.

[Abstract](1465)

Abstract:
Based on the study of the existing evolutionary algorithm (EA) and the immune principle of creatures, an immune evolutionary algorithm (IEA) is proposed. It is a global optimization method, in which offsprings are produced by the best individual of parents population and the elitist replaces population to converge. In the process of optimization, the new algorithm increases its convergence speed, combining certainty with randomicity effectively. A global convergence is proved by analysis of Markov chain. The test results show that IEA not only requires simple parameters but also can improve the convergence.

A Method for Investment Evaluation Based on Multi-criteria Random DEA Model

YING Song-bao, GUO Yao-huang

2003, 16(1): 92-96.

[Abstract](1491)

Abstract:
Based on the traditional DEA model, the random input and output indexes are analyzed in detail. A method for reliability calculation is proposed. To get more accurate evaluation, multiple criteria are added to the DEA model to get a multi-criteria random DEA model. An example is presented to show the application of the proposed model and the practicability and feasibility of the method for reliability calculation.

An Evaluation System of Development Level of Agricultural Modernization GUO Qia

GUO Qiang, LI Rong-xi

2003, 16(1): 97-101.

[Abstract](1477)

Abstract:
It is helpful to set up an objective, comprehensive and applicable system to evaluate agricultural modernization, so that the real development levels of agriculture can be determined, and deficiencies can be revealed for appropriate measures to be taken. Based on the concepts and standards of agricultural modernization available worldwide, and by consultation to experts, a new model and system to evaluate agricultural modernization is proposed. The system is used to calculate the development level of agricultural modernization of Chengdu city, which is one of key cities in the western China. The results show that the value system can reflects the actual development of agriculture modernization objectively.

Case-and Confidence-Level-Based Significance Ordering of Multiple Factors

ZHAO Yong, HUANG Ding-xuan, TANJian-xin

2003, 16(1): 102-105.

[Abstract](1484)

Abstract:
The significance ordering is one of the most important taches in researches concerned with multiple factors. Based on fuzzy cluster theory and significance principle in rough set theory, an objective method is proposed to determine the significance ordering of multiple factors, which is based on cases and fuzzy confidence levels. The procedures to abstract the significance of a factor from objective information are discussed in detail. An example is presented to show the application of the proposed method.

Differential Protection of Four-Limb Three Phase to Four Phase Transformers

GAO Shi-bin, CHENXiao-chuan

2003, 16(1): 106-110.

[Abstract](1099)

Abstract:
According to the relationship between currents in the primary and secondary windings of four-limb three phase to four phase transformers, three differential protection connection schemes are proposed. To meet the requirement to correct operation of differential protection in all situations, the three schemes are compared in the aspects such as the selection and connection of current transformers and the number of auxiliary current transformers, and so on. The analysis results show that there is the best one among the three schemes, in which only one auxiliary is needed.

An Automatic Chinese Postal Code Recognition System

LIU Wen, LIU Yong-hong, HE You-quan

2003, 16(1): 111-114.

[Abstract](1484)

Abstract:
An automatic Chinese postal code recognition system is introduced, which is an important part of postal mail sorting systems. The images of Chinese postal codes, handwritten or printed, on envelopes are captured with a CCD sensor. Then computer image processing technique and fuzzy recognition theory are used to process and recognize the codes. Experiment shows that the sorting speed of the system is over 5 letters per second, with an error being about 5%.

Virtual Reality System for Robotics Application

LI Gang-jun, CHEN Yong

2003, 16(1): 115-118.

[Abstract](1548)

Abstract:
The framework of VR (Virtual Reality) system, graphics-based virtual environment generation and real-time processing techniques are discussed in this paper. The structure and software of VR for robotics application is studied. A VR simulation system has been developed, which is an integration of space parameter models, kinematic and dynamic models, and some software, such as IRIS Performer, GL/OpenGL and 3DS Alias/wavefront. A simulated robot is presented as an example to show the performance of the developed system.

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2003 Vol. 16, No. 1