西南交通大学学报

Investigation on Shear Strength of the Oblique Section of Concrete Simply Supported Beam

ZHANGKai-jing

2000, 13(1): 1-6.

[Abstract](1242)

Abstract:
The main parameters affecting the shear strength of the reinforced concrete (RC), partial prestressed concrete (PPC) and prestressed concrete (PC) simply supported beams are analyzed and optimized; and the expression formula for the shear strengths of the concrete and the hooped reinforcement are putforward respectively. Based on the experimental results obtained bythe projectresearchteamand the regression analysis of the data tested in 871 beams from home and abroad, the united formulas for calculating the shear strengths of the RC, PPC and PC simply supported beams are presented, which have been adopted as the shear provision of“China Railway Bridge Code”.

Calculation of the Free Vibration Characteristics of Soil-Construction Interaction System

SHENAi-guo

2000, 13(1): 7-10.

[Abstract](1450)

Abstract:
Amodel forsoil-construction system is established bytransformingthe semi-infinite elastic ground into a complex stiffness embodied in the boundary layer between soil and construction, and the extended characteristic equation of the proposed model is derived. Through solving the characteristic equation, the effects of foundation soil on the free vibration characteristics of construction are studied, and some useful results are obtained.

A Study on Lateral Rigidity of Bridge Pier in High Speed Railway

NINGXiao-jun, LIXiao-zhen, QIANG Shi-zhong

2000, 13(1): 11-13.

[Abstract](1656)

Abstract:
Using the theory of coupled vibration between bridge and vehicle, this paper makes an initial study on the lateral rigidity of piers of a medium-small span simply-supported girder bridge. By calculating and comparing the vibration responses of vehicle and bridge on the piers with different lateral stiffness, it points out that piers should have enough lateral rigidity to ensure the safety and stability for the running of high speed vehicle

An Optimization Model for the Structure of Up-Flow Anaerobic Sludge Blanket Reactor and Its Use

CHENChun-guang, ZHENG Shuang-ying

2000, 13(1): 14-17.

[Abstract](1440)

Abstract:
According to the simplified flowpattern of an up-flowanaerobic sludge blanket (UASB) reactor, a structural optimization model is constructed. Through solving the optimization model and analyzing the correspondingresults, it can be concluded that (1) the structure design of the UASB reactor must be focused on the technical development in both the water distribution system and the three-phase separator to increase volumetric efficiency; and that (2) the combination forms oftheUASB reactorwithother processing structures should be developed due to the difficulty of increasing the hydraulic load in a common UASB reactor.

Discrete Element Simulation of Full-Course Kinematics of Rocky High-Speed Landslide

CHENG Qian-gong, HUHou-tian

2000, 13(1): 18-22.

[Abstract](1673)

Abstract:
Based on the models of landslide geometry, kinematics and dynamics, and through a distinct element numerical simulation, the process and mechanismof slope rock-massmoving and landslide damming in the big deformation stage after failure were revealed and reappeared, thus providing a scientific basis for the stability evaluation of landslide dam and the dynamic analysis of landslide damming by shock wave.

A Simulation of the Hydraulic and Mechanical Response to the Rainfall Process of the Typical Subgrade Slope in Chengdu-Chongqing Railway

XUZe-min, YANGLi-zhong

2000, 13(1): 23-27.

[Abstract](1283)

Abstract:
The typical subgrade slope of Chengdu-Chongqing railway is made of sandstone-mudstone layers and its weathering zones are covered by a sand layerwith a thickness of 2~5 m. Simulation tests indicate that the hydraulic and mechanical responses of the slope to a rainfall process is influenced by the initial permeability of the sand layer, the rainfall style and the rainfall amount. The rainfall process which can have a remarkable influence on the seepage field and stress field of the slope should satisfy the following requirements simultaneously: (1) due to a long time of hot weather before rain, the soil layer is intensely evaporated and its initial permeability is good; (2) the rainfall process begins with a moderate or a heavy rain, and continues for a longtime; and (3) the rainfall lasts a longtime, and the rainfall amount is great.

A Study on the Running Stability of Trains on Turnouts

WANG Ping

2000, 13(1): 28-31.

[Abstract](1445)

Abstract:
The spatial couplingmodel forrailwayturnoutsystem is improved inwhichthe vertical and lateral structure irregularities of turnouts and the variation ofwheel/rail contact geometry are taken into account. It is used to simulate the body hunting of trains and to analyze the running stability and safety of trains on turnouts.

The Excavation Procedure of Super-Large Underground Chambers and the Surrounding Rock Stability

YANGMing-ju, CHANG Shao-dong

2000, 13(1): 32-35.

[Abstract](1402)

Abstract:
During the construction of a group of super-large chambers, the most critical problem is the stability of the surrounding rock. So it’s necessary to analyze the excavation sequence and the stability of the underground chambers. In this paper, three main chambers of an underground hydropower station are excavated according to three different schemes. The stability of the underground chambers constructed in accordancewith the three excavation schemes are analyzed and compared by employing three-dimensional nonlinear finite method, supplying a reference for the construction design and field construction. In addition, some relevant comments and suggestion are put forward for the revealed problems in the surrounding rock stability.

On Confluence Movement Modes of Mixed Traffic Flow

LUOXia

2000, 13(1): 36-39.

[Abstract](1516)

Abstract:
This paper employs the process describingmethod to reveal the confluence movementofthe mixed traffic flow, obtaining that the mixed traffic flow unnecessarily obeys the rule-“the first arrived is served first”-in confluence process. Using the confluence acceptance probability theory, it is obtained that the same acceptance gap has different confluent probability for different vehicle types under mixed traffic flow, and so the space waste of acceptance gaps is produced. Meanwhile, the theories that the confluence area length and the driveway designing have effects on the service level and capacity of high-class highways, and that the confluence area is the watershed and the abrupt change area of the service level of the highways are explained by computer simulation.

Operation Simulation of a Highway Passenger Transportation Terminal System

YANQi-peng, GAO Shi-lian

2000, 13(1): 40-43.

[Abstract](1419)

Abstract:
The characteristics of a highway passenger transportation terminal system are analyzed. By employing the simulation optimization theory and method, the operation simulation framework of the system is constructed; the simulation programthat has been confirmed effective iswritten; and thewhole process of operation of the system is reappeared. Through the computer simulation, the rationality of the station-yard layoutof passengertransportation systems can be evaluated, thus affording a scientific basis forthe passenger station-yard programming. For the present station-yard systems, the operation plans possible to be adopted can be previewed, so that the traffic organization plans can be optimized. A simulation example is also presented.

Solving Traffic Equilibrium Assignment Problem with Genetic Algorithm

CHEN Yan-ru, PUYun

2000, 13(1): 44-47.

[Abstract](1485)

Abstract:
This paper proposes a parallel processing method of genetic algorithm for the traffic equilibrium assignment problem with fixed traffic demand in order to forecast the traffic volume accurately. In the algorithm design, some improved steps such as the multi-dimensional parallel crossover, variational rates of crossover and mutation, the elitism and the punishment of objective function are taken, so that the computing speed is greatly improved; the computation time and the assignment complexity are substantially reduced. It founds a new way for traffic assignment problems, and at the same time shows a potential practical prospect for the genetic algorithm to be used in the traffic programming.

The Spontaneous Configuration of Ferroelectric-Ferroelastic Materials:Ⅱ ———Polycrystalline Materials

ZHANG Ying

2000, 13(1): 48-53.

[Abstract](1078)

Abstract:
As the internal energy densityof ferroelectric-ferroelastic single cystals is the non-convexfunction of the transformation gradients and the electric displacements in the process of polarization, in natural conditions (i.e., without external forces and external electric fields), the stable spontaneous configuration of a ferroelectric-ferroelastic polycrystalline material consists of a coarse mixture of various ferroelectric domains. In this coarse mixture, the volume fractions of electric domains are determined by the continuity requirements of the displacement and the electric displacement on the grain boundaries. Because various kinds of twins can be formed in the material, the volume fraction of the domainswith the same spontaneous deformation gradient depends upon the orientations of the grain boundaries, the orientations of the twining crystal lattices, and the twiningmode. In addition, the volume fraction of ferroelectric domains also depends upon the shape of the twining regio

Spline Finite Point Method for Geometrically Nonlinear Analysis of Arch Structure

DUANHai-juan, QINRong

2000, 13(1): 54-56.

[Abstract](1324)

Abstract:
A spline finite point method for geometrically nonlinear analysis of arch structure is presented. With the displacement componentsuandwtreated as fundamental unknown variables, and the cubicB spline functions as displacement functions, the nonlinear stiffness equations of spline discretization are established based on the principle of minimum potential energy, and the precise explicit expression of the nonlinear tangential stiffness matrix is derived.

On the Homotopy Iteration Method and Its Application in the Mechanism Problems

LILi, ZHANGJian, CHEN Yong

2000, 13(1): 57-60.

[Abstract](1059)

Abstract:
Based on the analysis ofthe zero set characteristics ofthe nonlinear polynomial mappinghomotopy function, a homotopy iteration method with an improved homotopy tracking scheme is proposed in this paper, and the feasibility and reliability of the homotopy iteration method for solving nonlinear polynomial systems is proved. The proposed method possesses a high efficiency in solving the high deficient polynomial systems. Numerical examples of mechanism problems demonstrate the efficiency and reliability of the method.

Radiation Properties of Wire Meshes

DENG Zhi-hui, WANG Yun-shi

2000, 13(1): 61-64.

[Abstract](1059)

Abstract:
Amethod for calculatingthe radiation properties ofwire meshes is presented, inwhichthe effects of scattering and surface characteristics are both taken into consideration, and the stratified superposition principle and a double-flux model are employed. Finally the calculated results are compared with those obtained by projective theory and Mie electromagnetic theory, and confirmed by a high temperature wind tunnel experiment. It is shown that the results by this method coincide with the experimental results well.

A Genetic-Neural Network Algorithm in Optimum Design

ZHAO Zheng-jia, HUANGHong-zhong, CHENXin

2000, 13(1): 65-68.

[Abstract](1624)

Abstract:
Agenetic-neural network algorithmforoptimumdesign is developed. In the algorithm, the global property of genetic algorithms (AG) and the parallelism of artificial neural networks (AN2) are combined; GA provides global initial solutions, fromwhich AN2obtains the final solutions. Thus, the defects of slow convergence with GA and easily falling into local solutions with AN2can be overcome. An applied example shows that the global property of the new algorithm is better than that ofAN2, and its convergence is better than that of GA.

The Reliability Analysis of the Tilting Mechanism Control System of Tilting Trains

DAIXiao-wen, YANJun-mao, BUJi-ling

2000, 13(1): 69-71.

[Abstract](1382)

Abstract:
The failure tree affecting the reliability of the tilting mechanism control system of tilting trains is introduced. Then the redundant control system is used to serve as the reliability optimization model of the system, and the formula of reliability is derived. At the same time, the redundant system is achieved by means of the automatic change-over switch and the network technology, and their compositions are described. It is pointed out that using the network technology to realize the redundancy is a good choice because it is convenient and can improve the reliability of the system.

An Efficient 4-Node Plane Hybrid/Mixed Element with Tensorial Formulation

YANG Fan, WANGJun, CHENDa-peng

2000, 13(1): 72-76.

[Abstract](1455)

Abstract:
The paper is mainly concerned with developing a kind of tensorial formulation scheme for low- order hybrid/mixed finite elements based on Hellinger-Reisser variational principle. By making use of the invariance properties of tensors, the disadvantages due to coordinates transformation are totally avoided. Also, inmatchingthe derived strain field, which is in tensorial form, a properselection ofthe optimal stress field is successfully achieved on the basis of“the consistency of one stress parameter with one independent deformation mode”. Thus, a 4-node plane quadrilateral element is obtained. Numerical simulations reveal the remarkable characteristics of the present elements, such as invariance, robustness, having no zero energy,etc.

Schema Theory on Natural Number Coding

LIJun, XIEBing-lei, GUO Yao-huang

2000, 13(1): 77-80.

[Abstract](1511)

Abstract:
In this paper, based on the analysis of the genetic algorithm on binary coding, a preliminary discussion is made on the genetic algorithmof natural number coding. The schema and the order of schema which are based on natural number coding are discussed, and the correspondingschema theory is derived. It is concluded that the derived theory is analogous to the schema theorywith binary coding. The conclusion is helpful in explaining the convergence of the genetic algorithmwith natural number coding.

Deformation Analysis of SMA Springs and Its Application to Vibration Control

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

2000, 13(1): 81-85.

[Abstract](1106)

Abstract:
In this paper, the constitutive model by Brinson (1993) is modified, and the constitutive model suitable for shape-memory alloy (AMS) springs is built. Based on the constitutive model, the deformation of SMAsprings is analyzed. It can be seen thatthe stiffness ofSMAsprings is variable under different load and temperature conditions, therefore changing the stiffness of the SMA springs can easily control the resonance frequency of a system.

Application and Design of the Wavelet Filter in Weak Signal Detection

LIShi-ling, LIHe-sheng, LI Zhi

2000, 13(1): 86-89.

[Abstract](1474)

Abstract:
Awavelet energy accumulation model, which can be used to obtain the accumulation in different decomposition scales, is designed on the basis of multi-scale decomposition properties ofwavelet transform. Furthermore, a wavelet energy detectingmethod forweak signal detection is presented, and the detection of signalswith low signal to noise ratios (SNR) is experimentally simulated. The simulation results show that the detecting method proposed in this paper is fairly effective in detecting low SNR weak signals, and is advantageous over the conventional method which uses accumulating and averagingwithin a pulse.

A Study on Optimum Design of Trapezoid Movable Core Alternating Current Arc Welding Machines

LvQi-bing, QUJin-shan, GULiang

2000, 13(1): 90-93.

[Abstract](1376)

Abstract:
The object functions of optimum designs are discussed for trapezoid movable core alternating current arc welding machines. Based on the discussion, a mathematical model for the optimum designs is built, and computer software for the optimum design is programmed, with which the optimum designs of welding machines can be done. The result shows that the alternating current arc welding machines designed with the software have fairly low production costs and high comprehensive performances.

Research on the Comparing-Mapδon the Symbolic Space (Ⅰ)

LIUJia-cheng, GUO Yao-huang, WANGLi

2000, 13(1): 94-97.

[Abstract](1085)

Abstract:
In this paper, the comparing-mapδon the symbolic spaceΣ2is introduced. Then an infinite 0-1 matrix is constructed to prove thatδis topologically conjugate to the shiftmapσ. Furthermore, the characters of periodic points of the comparing-mapδare studied, and several equivalent conditions for certain periodic points and generalized periodic points are obtained.

Fuzzy Approach for Bi-Level Programming Problems (Ⅱ)

PEI Zheng, HUANGTian-min

2000, 13(1): 98-101.

[Abstract](1270)

Abstract:
A fuzzy mathematical approach is proposed for bi-level programming problems in which the upper-level has constraints and the lower-level consists ofNindependent programming units. A bi-level programming problem is divided into many classical ones, then by introducing the concepts of membership functions, the solution of each classical programming problem is discussed with three theorems. Consequently, the bi-level programming problem can be transformed into solving a classical linear programming problem, enabling the problem being simplified.

A Hybrid Learning Algorithm for Extracting and Optimizing Fuzzy Rule Bases

TANG Yong-chuan, HUANGTian-min

2000, 13(1): 102-105.

[Abstract](1611)

Abstract:
This paper proposes a hierarchical learning algorithm for optimizing fuzzy rule bases. In this algorithm, Takagi-Sugeno fuzzy neural network is used for the parametric learning of a fuzzy rule base with steepest descent method. Then, the structure of fuzzy rule bases is optimized with the binary coding method, in which a rule corresponds to a gene bit, and a rule base to a chromosome. This hierarchical learning algorithm can reduce the redundant rules and simplify the fuzzy rule base. A computer simulation verifies the effectiveness of the proposed algorithm.

Study on Dynamic Income Present Value Method for Appraising Mineral Resource Assets

ZHANGJin-suo, LIHuai-zu, HEDe-quan

2000, 13(1): 106-120.

[Abstract](1326)

Abstract:
The authors of this paper, by making researches on the income present value method for appraisingmineral resources assets using time series analysis theory and asset pricing theory, establish a dynamic model of forecasting the future net incomes of the mineral resource assets to be appraised, and put forward a method for calculating the history data of discount rates. Based on that, they build a dynamic model for forecasting the future discount rates, which is similar to the dynamic model for forecasting net incomes. These models and method lay a foundation for extending the static income present value method into the scientific and practical dynamic income present value method.

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2000 Vol. 13, No. 1