西南交通大学学报

Groundwater Age Determined with Environmental Tritium in Qinling Tunnel Area

LIU Dan, LI Qi-bin

2002, 15(6): 601-605.

[Abstract](1285)

Abstract:
Groundwater residence time is quantitatively determined with environmental tritium and an isotopic mathematical model in Qinling extra-long tunnel area. The mean age of all the groundwater is over 43 years, and even up to 70 years in the ridge zone, obviously older than that of shallow groundwater aged only 1 to 5 years. This shows great differences between the two areas in dynamic features. The age of the deep groundwater in slop zones trends to increase towards the tunnel entrance and exit, which indicates that the fissured water-bearing medium is characterized by hydraulic continuity within the tunnel area. This property is of great significance to rationally building the mathematical model for prediction of the waterflow to tunnel.

An Analysis on Trend and Technology Demanded of Urban Rubbish in China

YU Su-jun, YANG Li-zhong, LI Xiao

2002, 15(6): 606-609.

[Abstract](1055)

Abstract:
A analysis on the actualities and a certain problems dealing with headstream, sanitary fill, cremating process and composting process in treatment and disposal of urban refuse in China is conducted. And in accordance with such situation some viewpoints are rendered including that headstream should focus on picking out the battery and the plastic first, incinerator should combine together in drawing in foreign technique with self-reliance, and composting process should cover with the treatment of livestock manure. And the technology demanded is brought up in relation to the every kind of circumstance.

Characteristics of Seepage Water Quality of Baisha Filter Well in Chongqing

LI Xiao, YANG Li-zhong, YU Su-jun

2002, 15(6): 610-614.

[Abstract](1319)

Abstract:
Analyses of the seepage water quality in the filter well constructed by Baisha waterworks in Jiangjin, Chongqing reveal that, through infiltration of sandy gravel in the river bed, the micro- polluted, high turbid river water can be converted into seepage water with suspended substances and bacteria well removed and turbidity visibly reduced. The contents of NO-3, COD, BOD and TOC in the seepage water are obviously reduced, and the removal ratio is over 75%. The change of major components in content is remarkable, while the micro-components have not clear change in content. The quality of the seepage water accords with the national standard for drinking water quality, and can be used as domestic water directly.

Influences of Rail Creep on the Longitudinal Forces and Displacements of Welded Turnout

WANG Ping, GUO Li-kang

2002, 15(6): 615-619.

[Abstract](1429)

Abstract:
Moving wheel loads will cause creep and additional temperature stress in continuously welded rails (CWR). The difference in the structure of frog and frog heel will result in different transmission mechanism of the longitudinal forces in welded turnouts. Therefore, the welded turnouts with different structures have different mechanical properties and deformations. In this paper, a comparative analysis is made of the influences of the transmission mechanisms of longitudinal force of welded turnouts with different structures on the loads and deformations of various components. The analysis results show that raising track resistance and controlling the creeping displacement of the welded turnouts are beneficial to enlargement of the temperature scope for laying welded turnouts.

Laying 60 kg/m Rails on Sharp Curves along Guiyang-Nanning Line

LI Cheng-hui, GUO Li-kang, GAO Feng

2002, 15(6): 620-622.

[Abstract](1570)

Abstract:
A mechanical analytic model is built to study the lateral force acting on the rail fastenings and the track geometry error in sharp curves during laying 60 kg/m rails in sharp curves. Computation and analysis are made based on a curve with the smallest radius of 177.1 m along Guiyang-Nanning line. The results show that when placing 60 kg/m rails in sharp curves, the track geometry errors are within the allowable limit, and there is no need to take extra measures to strengthen the track structure.

Determination of Partial Coefficients of Structural Reliability Design

YAN Song-hong, ZHOUJia-mei, GAO Bo

2002, 15(6): 623-627.

[Abstract](1489)

Abstract:
Based on the geometrical meaning of the reliability index b and the basic concept of partial coefficients, the calculation method for the partial coefficient in the structure limit states design equation is discussed under the objective reliability index bnom by constructing a virtual limit state camber. Meanwhile, the calculation method for the partial coefficient under an ordinary distribution of correlated variables is also discussed. A numerical example shows the effectiveness of the methods proposed.

Experimental Study on Erosion Stability of Thick Layer Base Material Spraying Bio-Slope-Engineering

ZHANG Jun-yun, ZHOU De-pei

2002, 15(6): 628-631.

[Abstract](978)

Abstract:
The erosion stability of base material mixture is one of the important indices of evaluating thick layer base material spraying bio-slope-engineering. Based on artificial rainfall experiments, the effect of base material mixtures with different compositions on its erosion modulus is studied. The results show that the erosion stability of base material mixture is decreased by the increase of planting soil and the reduction of organic materials and fibers, but is increased by slope vegetation.

Real-Time Generation of Dynamic Terrain Based on Adaptive Quadtree

PENG Yi-pu, ZHAN Wen-hua

2002, 15(6): 632-636.

[Abstract](1334)

Abstract:
A multiresolution and real-time terrain generation model based on adaptive quadtree is presented. The algorithm of the model includes the adaptive inputting and static culling of raw data, renewing of error evaluation criterion, and frame-to-frame coherence. Experimental results show that this algorithm is simple and effective, and supports the interactive and real-time rendering of terrain surface models.

The Feasibility of Trigonometric Height Survey for Replacement of Order Levelingin Wide Network of Rivers

HAO Chuan-cai, LIU Cheng-long

2002, 15(6): 637-641.

[Abstract](1149)

Abstract:
Based on a statistics analysis of the experimental data of trigonometric leveling networks at four extra-long bridges such as the Humen bridge, etc., comparisons are made in forward and backward altitude differences, loop closures, the third-and the fourth-grade-leveling surveys difference limitations, and the altitude differences between trigonometric height survey and order leveling at common points. It is verified that in networks of rivers, using trigonometric height survey to replace the fourth-grade-leveling is completely feasible for the leveling measurement of crossing rivers, but when using it to replace the third-grade-leveling, the reliability is only about 75%.

An Isotropic Viscoelastic Model Coupled with Hydrothermal Effects

WANG Jun, YANG Fan, CHEN Da-peng

2002, 15(6): 642-646.

[Abstract](1234)

Abstract:
To characterize the behavior of polymers and the mutual influences among moisture, temperature, and stress in polymers, a constitutive equation for isotropic viscoelastic materials, with a coupling among behaviors of moisture diffusion, heat conduction and mechanical deformation, is developed using the Helmholtz free energy and irreversible thermodynamics. In the equation, internal variables are introduced to describe the viscosity of the materials. It is shown that through simplification some currently used computational models can be generated from the equation proposed in this paper.

A Monte-Carlo Stochastic FEM Based on Conjugate Gradients Method

YANG Jie, CHEN Qiu

2002, 15(6): 647-650.

[Abstract](1613)

Abstract:
An improved Monte-Carlo stochastic FEM based on polynomial preconditioners is established through introduction of the conjugate gradients method into the traditional Monte-Carlo stochastic FEM. In the improved FEM, a certain characteristic sample is obtained first; then, using it as a preconditioner, the other samples are solved by polynomial preconditioners for conjugate gradients method. A comparison between the improved Monte-Carlo stochastic FEM and the Neumann expansion-based Monte-Carlo stochastic FEM shows that the latter is a retrogression of the former, and that the former is more efficient in dealing with stochastic problems. Finally, a numerical example is given to illustrate the advantage of the new method proposed in this paper.

The Coupling Relation Between Structural Parameters and Dynamic Indexes of Gantry Crane

CHENG Wen-ming, WANG Jin-nuo, DENG Bin

2002, 15(6): 651-654.

[Abstract](1341)

Abstract:
According to the characteristics of the existing serial elastic dynamic vibration model of three masses and three degrees of freedom for a gantry crane with elastic trolley frame, the numerical solutions to the dynamic behaviors of the system are obtained through modal analysis. The coupling relationship and variation law between the structural parameters and dynamic indexes of the gantry crane is emphatically studied. It reveals that the rail gauge of the trolley has a big effect on the natural frequency of the system; however, the stiffness coefficients of the girder and the trolley frame have little effects on the dynamic factor of the system.

Calculation of Stress Intensity Factors for Cracked Diesel Engine Crankshafts

WANG Guang-qin, LI Xing-ren, GAO Qing

2002, 15(6): 655-658.

[Abstract](1371)

Abstract:
Astress analysis of a diesel engine crankshaft is made by FEM based on dynamics analysis to determine the position of the initial crack and its propagation direction. The stress intensity factors of the cracks at various depths are calculated using displacement method on a substructure model, thereby the expression for the geometry factor of a 16V240ZJB diesel engine crankshaft is obtained by curve fitting. This work can afford a theoretical foundation for the fatigue and reliability analyses of diesel engine crankshafts of the same or alike types.

Selection of the Learning Samples of Neural Networks for Internal-Combustion Engine Emission

ZHOU Bin, LI Yu-mei, SHIGA Seiichi

2002, 15(6): 659-663.

[Abstract](1461)

Abstract:
According to the variation characteristics of the operating condition of internal- combustion engines, an improved orthogonal design method which considers the changes on factor boundary is proposed to choose learning samples of neural networks. The results show that the forecasting precision of the emission models built on 6135ZG diesel engine under stable operation increaseswith the increase of the level of the diagonal intersection table. Even if the sample is a diagonal intersection of level 3, the emission-forecasting model can be built with an error less than 5.7%. Compared with random selection of samples, the improved orthogonal design method is characterized by easiness and less work load.

Dynamic Performances of the Bogie with Magnetic Fluid Coupled Wheelsets

CHI Mao-ru, WANG Kai-wen, ZHANG Wei-hua

2002, 15(6): 664-668.

[Abstract](1688)

Abstract:
A dynamic calculation model for vehicles with magnetic fluid coupled wheelsets is established. Using numerical method, a dynamic simulation is made of the dynamic performances of a bogie equipped with magnetic fluid coupled wheelsets, and the influences of the front and rear magnetic fluid wheelsets on the dynamic performances of the bogie is obtained. A dynamic performances comparison between bogies with traditional fixed wheelsets, with independently rotating wheels, and with magnetic fluid coupled wheelsets reveals that a reasonable coupling factor of the front and rear wheelsets of bogies can help improve the dynamic performances of bogies.

A Distributed Visual Simulation System for Train Simulators

SUHu, ZHOU Mei-yu

2002, 15(6): 669-672.

[Abstract](1368)

Abstract:
A multi-channeled visual simulation system is developed for train simulators. In the system, the real-time rendering of three channel output images of the scenes a train passes by is performed through the parallel computation on three networked PCs. The structure, implementation and experimental results of the distributed visual simulation system are presented. The system can replace costly graphics workstations to accomplish generation of real-time multi- channel output images in train simulators.

New Approaches for Improving Detection Efficiency of Intrusion Detection Systems

DAI Yun, FANPing-zhi

2002, 15(6): 673-676.

[Abstract](1417)

Abstract:
The growth of network bandwidth requires that intrusion detection systems (IDSs) have higher performances than ever. In this paper, two efficiency detecting approaches of IDSs are presented. One is to use an IDS traffic controller managed by an appropriate traffic control strategy to perform payload balancing; the other is to use attack level classification according to detection cost to arrange the tasks of different IDS. By using the two methods, the IDS traffic payload is balanced, resulting the increased overall detection efficiency; in addition, different IDSs are complemented each other, therefore the anti-capability of IDSs can be enhanced.

An Immune Optimal Algorithm and Its Application

SU Cai-hong, ZHUXue-feng, MAO Zong-yuan

2002, 15(6): 677-680.

[Abstract](1343)

Abstract:
An immune algorithm of a mathematically optimal structure model is derived based on the natural immune system mechanism. The algorithm combines the evolution function of traditional genetic algorithms and the density mechanism in creatures’immune procedure. The adjustment of antibodies is realized by the expected breed rate to improve the premature convergence. The algorithm is used to solve for the optimization of Rosenbrock function, and compared to a genetic algorithm. The results show that the immune algorithm performs better in the aspect of global and local search ability and search speed

A Precise Analysis of Performances of Receivers in CDMA Systems

LIU Wei, ZHU Chang-qian

2002, 15(6): 681-683.

[Abstract](1066)

Abstract:
Considering the limitation of the method based on Gaussian approximation for analysis of multi-user systems, a precise analysis is made of the performances of the receivers in CDMA systems, and the curves of bit error rate (BER) are obtained for the systems. A numerical simulation shows that the precise analysis method proposed in this paper is more accurate than the method that is based on Gaussian approximation.

Taylor Series Expansion Method and Its Performance Analysis

LI Li, DENG Ping, LIU Lin

2002, 15(6): 684-688.

[Abstract](1172)

Abstract:
The channel model suitable for TDOA techniques is discussed, and the typical location TDOA algorithm, Taylor series expansion method, is analyzed. The traditional Taylor series expansion method is improved by solving its convergence problem. Then, the performances of the improved method are simulated under different channel environments and cellar base station distributions. And, a comparison is made between the improved Taylor series expansion method and the other methods in influences of various parameters on the performances.

Microwave Image Reconstruction of a Perfectly Conduction Cylinder by Real-Coded Genetic Algorithm

ZHONG Xuan-ming, LIAO Cheng, YANG Dan, YANG Zhou-bing, MENG Fan-bao

2002, 15(6): 689-692.

[Abstract](1415)

Abstract:
A microwave imaging approach based on real-coded genetic algorithm for a perfectly conduction cylinder in free space is presented. The contour of the cylinder is expressed by a shape function which is approximated by trigonometric series. The scattering problem is simulated by point-matching moment method; the inverse scattering problem is converted into a restrained optimization problem, that is, the coefficients of the trigonometric series are the variables to be optimized, and the optimization is made by minimizing the relative error between the measured amplitude of the scattered electric-field and the simulated one. The effectiveness of the image reconstruction method proposed in this paper is verified by an examples.

Parameter Analyses in the Model of Profit Sharing and Valuation of Technical Assets

FAN Li-li, WUNa, MA Yue

2002, 15(6): 693-697.

[Abstract](1313)

Abstract:
The accuracy of the income allotment algorithmic model used for evaluation of technical assets is dependent on the determination of each parameter, and this is also a problem that is easy to arouse controversies. A way for calculating the income allotment proportion in the pricing model of income separation is introduced. The different meanings of several expected revenues and their determination methods are expounded. The calculation methods for discount rates and for different technical assets and their life periods are put forward, and some problems that need to be paid attention to are also put forward. Finally, a practical example is used for analysis of the income separation.

A Multidimensional Game Model and Its Equilibrium in Bertrand Duopoly

TAN De-qing, HUPei, OUYANG Yan-kun

2002, 15(6): 698-702.

[Abstract](1260)

Abstract:
According to the phenomena of games among corporations in economic activities, the paper puts forwards a concept of multidimensional game, then describes its characteristics and strategy forms and extends the Nash equilibrium to the multidimensional Nash equilibrium. Meanwhile, a two-dimensional static game model in duopoly and its two-dimensional Nash equilibrium on price strategy are discussed for two kinds of products with a certain substitutive relationship. It is shown that the Bertrand game model, as well as its Nash equilibrium, is the special case of the two-dimensional Bertrand model proposed in this paper.

Evaluation of the Scientific and Technological Advancement of Western China

LUO Li, HUXiu-qiang

2002, 15(6): 703-708.

[Abstract](1031)

Abstract:
An improved DEA (Data Envelopment Analysis) method is used to evaluate the scientific and technological advancement of western China. The advancement rates of production technology, efficiency, and science and technology in different regions of western China from 1997 to 1999 are calculated, and the contributions of these advancement rates to the economic growth of each region are also calculated. The mean values of these evaluation indexes are compared with the national mean values to find out the advantages and gap between them, and to analyze the existing problems. This study is to provide a scientific foundation and a decision reference for reinforcement of the work of scientific and technological advancement in western China.

Customer Satisfaction Based on Limited Rationality and the Strategies

CHENXu, WUZhen-ye

2002, 15(6): 709-714.

[Abstract](1317)

Abstract:
Customer satisfaction is an important measure to improve the competitive power of enterprises. This paper begins with a summary of theoretical researches on customer satisfaction at home and abroad, followed by a discussion on the essential implication of customer and customer satisfaction based on limited reason. Then, a multi-variable customer satisfaction model is established, and the relationships among the multi-variables composing the model are analyzed. Finally, the strategies for customer satisfaction are studied from four aspects, i.e., re-engineering of corporation image, comprehensive customer satisfaction, visual flexible decision-making, and customer relationship management.

Rational Number of Station Tracks in Single-Track Railway

WANG Jian-jun, JIAHua-qiang

2002, 15(6): 715-718.

[Abstract](1505)

Abstract:
Using the simple analysis model, queuing analysis model and simulation analysis model respectively, analyses are made of the number of tracks in various types of stations such as technical service stations, the two stations at the ends of a limiting section, and the general passing stations. It is concluded that the determination of track number should fulfill the requirements of technical stopping, limiting stations, long-term plan, and the speed raising of passenger trains; and that the simple analysis model, queuing analysis model and the simulation analysis model are practicable.

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2002 Vol. 15, No. 6