西南交通大学学报

Behavior and Earth Pressure of the Retaining Piles with Anchors for Deep Excavation

XIA Yong-cheng, DONGDao-yang, HUMin-yun

2000, 13(2): 111-115.

[Abstract](1378)

Abstract:
The deep excavation engineeringof the Overseas Exchange Centerof Chengdu takes a structure of retaining piles that use anchors and have ring beamto join the tops of the piles. In this paper, based on the measured reinforcement stresses in the piles during the foundation pit’s excavation, the corresponding mo- ments in the piles are obtained, and the deformation condition of the piles and the earth pressure acting on the piles above the excavation surface are analyzed. Results showthat the ring beam has an appreciable re- striction effect on the lateral displacement and rotation of the pile tops, and the deformation condition of the piles is completely different from that of upright free-head shafts. Under the normal working condition of the retaining structure, the earth pressure above the excavation surface on the piles is quite different from the classical earth pressure theory in distribution and value,

Permanent Deformation of Subgrade Soils in Flexible Pavement

QIUYan-jun, SUNZhen-tang

2000, 13(2): 116-120.

[Abstract](1345)

Abstract:
A practical method for calculating permanent deformation of subgrade soils in flexible pavements is proposed. Based on the general principle that stress analysis and strain calculation are not integrated through the rigorous constitutive matrix in the design and analysis of flexible pavements, a permanent defor- mation model is used in the investigation, and the steps to calculate the permanent deformation are given, with a calculation example demonstrated. Meanwhile, the influence of permanent deformation on the two major pavement distresses is also explored. The general concept proposed in the paper is also helpful to the better understanding of the design theory of highway flexible pavements and railroad tracks.

An Experimental Study on the Self-Organized Criticality of Sand Pile Model with One-Grade Slope

LI Yuan-fu, YAOLing-kan, DENG Yu-cai

2000, 13(2): 121-125.

[Abstract](1229)

Abstract:
The sand pile model can serve as a paradigm for self-organized criticality. This paper reports an experimental study on the sand pile model with semi-boundless collapsed loose slope under inclined plane. Experimental results indicate thatthe self-organized criticalityof a sand pile is related to the granular non-u- niformity, which forthe firsttime experimentally proves the influence of organization principles of the system on the phenomenon of self-organized criticality.

Self-Vibration Characteristic Test of Long-Span Bridges by Means of Environment Random Excitation

TANGHuai-ping, WANG Feng-qin

2000, 13(2): 126-128.

[Abstract](1407)

Abstract:
Structural self-vibration characteristic test is one of the most important contents of long-span bridge quality evaluation. In this paper, a quick and reliable method of environment random excitation is proposed for self-vibration characteristic test. Based on the theory of IDTmodal parameter identification in time domain, and using the impulse response signals acquired from each structural measuring point, the method is used to analyze the self-characteristics of a long-span bridge.

Experimental Research on Limit Torque of RC Members under the Combined Action of Axial Tension and Bending Twisting Moment

DUZan-hua

2000, 13(2): 129-132.

[Abstract](1205)

Abstract:
According to the experimental results of limit torque in eight RC structural members under the combined action of axial tension and bending twisting moment, the author studies the damage forms of the members, the stress-strain variation law of the longitudinal and the crossed steels. Based on the theory of changeable angles in the truss, the author derives some relevant equations forthe RCstructural members un- der the combined action of axial tension and bend twistingmoment. The auther also proposes a practical for- mula for calculatingthe ultimate torque ofthe memberswhich is underthe combined action of a comparative- ly large axial tension and bending twisting moment.

A Study on Crack Resistance of Subway Station Top Floor during Construction

ZHANGJie

2000, 13(2): 133-136.

[Abstract](1143)

Abstract:
The cause of subway station top floor cracking during construction is analyzed, and the tempera- ture stresses ofthe monitoringsection are computed usingthe practical test data. It is pointed outthat during construction the hydration heat will not cause the subway station top floor to crack, and that in designing structures of the same kind, it is unnecessary to design the after-pouring construction joint. On the other hand, using cement of low hydration heat or decreasing the amount of cement is important.

Experimental Study on the Wall Jet in Defined Space during Tunnel Construction

LIGang, YANGMin, HUANG Ru-qin

2000, 13(2): 137-140.

[Abstract](1493)

Abstract:
The purpose of this paper is to studythewall jet in defined space duringtunnel construction. For two-dimensional wall jets in defined space, through a lot of experiments and theoretical analyses it is con- cluded that: (1) the flowfield ofwall jet in defined space can be categorized as thewall jet zone, the back flow zone and the eddy zone; (2) the boundaryof awall jet can be approximately regarded as a straight line and the angle of spread is 7.67 degrees; (3) the flowmotions in the developing region and fully developed region of the flow are similar; and (4) along the distance, the maximumvelocity of profile decays faster in defined space than that in half-limitless space; and the length of the back flowzone in a defined space wall jet increases with the increase of the pipe flow. In this paper, the formula for calculating the length of the back flow zone is presented.

A Study on the Fractal Interpolation of Topographical Data

ZHANG Shan-shan

2000, 13(2): 141-144.

[Abstract](1119)

Abstract:
The Fundamental concepts of fractal, iterated function system (IFS) and fractal Brownian motion (FBM) are described briefly. The fractal interpolation methods of topographical data based on IFS and FBM are introduced, and some concrete algorithms and practical examples are presented.

Application of a New Type of Punched Agitator to Phosphoric Acid Reaction

OUYang-feng

2000, 13(2): 145-147.

[Abstract](908)

Abstract:
The production techniques and reaction device of producing phosphoric acid by wet process are introduced. A newtype of agitator applicable for phosphoric reactors is presented, and its operation perfor- mances in phosphoric acid reactors are discussed from the reaction mechanism. It is thought that the use of the punched agitator can intensify the eddy current diffusion and enhance the liquid turbulence degree. Thus, the reaction intensity, the phosphorus decomposition and the recycling rate can be improved; the en- ergy consumption can be decreased; and better phosphoro-gypsum crystals is obtained. The result is verified by practical experiments conducted in a factory.

Admittance Characteristics of Wheelset under High Frequency Excitation

WEI Wei, ZHAI Wan-ming

2000, 13(2): 148-151.

[Abstract](1669)

Abstract:
The admittance characteristics of four kinds of Chinese wheelsets under high frequency excitation are analyzed. Results showthat the highest admittance is in the axial (i.e., lateral) direction ofwheelset spoke, and the main way to reduce the high frequency vibrations is to reduce the wheelset spoke lateral ad- mittance. Reducing wheel vibrations can be accomplished by adjusting the wheelset stiffness distribution, making full use of the admittance phase, and modifying the wheel-rail contact characteristics.

A New Index for Ride Quality Analysis of Automobiles: the Coefficient of General Vibration

DUZi-xue

2000, 13(2): 152-157.

[Abstract](1201)

Abstract:
This paper puts forward a newindex: the coefficientofgeneral vibrationCgv—for evaluating au- tomobiles’ride quality. Taking a Changan bus as an example, it presents the methods of determining the weighted coefficients of velocity, location, road proportion and anthropological factor,etc., which are to be used in obtaining the index ofCgv. These methods can make it more convenient and reasonable to predict the ride quality of a concept automobile.

On Measuring Methods for Parameters of Car Body

CHENJian-zheng, ZHANG Wei-hua, CHENLiang-qi

2000, 13(2): 155-159.

[Abstract](3947)

Abstract:
Based on the discussion of the significance of measuring the car bodies dynamic parameters of railway vehicles, the methods tomeasure a car body sweight (mass), center of gravity and moment of iner- tia are proposed. The advantages and feasibilityofthese methods are analyzed and compared, and the calcu- lation methods and calculation formulas for the parameters are given. In addition, the car body s parameter measurement of an actual passenger car is introduced and the measured results are presented.

Visualization of Computing Model of Locomotive Dynamics

DING Guo-fu, WANGJin-nuo, WUPing-bo

2000, 13(2): 160-163.

[Abstract](1762)

Abstract:
A locomotive dynamics simulation systemgenerally consists of model building, model calculation and model display. This paper puts forward a CAD method that is based on three-view drawing. In this method, the initial data chains of a locomotive dynamics simulation model can be visually attached to a graphics interface to build the geometry model of the locomotive dynamics simulation, which is convenient for model building and modifying, and also convenient for the model to be passed to its simulation calculation. Meanwhile, on the basis of the results of the model calculation, a three dimensional animation based model dynamic displaying method is proposed, which can realistically simulate the model simulation results and efficiently check the properties of the locomotive dynamics model. These two research items can further improve the integration of locomotive dynamics simulation systems.

A Study on the Development Platform of Dynamic Graphic Simulation System for Locomotive Circuits

TANG Zhi-hui, CHENHua-bin, ZHOUMei-yu

2000, 13(2): 165-169.

[Abstract](1352)

Abstract:
The current computer dynamic graphical simulation systemwhich simulates the locomotive circuit process is only used fortrainingtrainees, and cannot be used bythe designerof locomotive electric circuits. Moreover, because of the rapid change of locomotive types, the designers have to repeatedlywrite and input the logic control programs. It is notonlytime consumingbut difficult aswell. In viewofthis status quo, the authors ofthis paper putforward amethod for designing a development platformof dynamic graphical simula- tion systemfor locomotive circuits, inwhich logic simulation files are automatically produced by computer it- self according to the input electric circuit principle graphs.

A Design Basis for Collector of Maglev Trains

HUJi-shi, PANHui-long

2000, 13(2): 170-173.

[Abstract](1706)

Abstract:
The Maglev train drived by short-stator linear motor acquires power from conductor rail through contacting collector. This paper, based on the analysis of the motion characterof theMaglev train, puts for- ward a main design basis for the Maglev train collector. This design basis is applied to the collector design of the Maglev test line in Qingchengshan. Besides, it also provides reference for urban light railways.

Distance Properties of Turbo-Codes and Viterbi Decoding Method

ZHANG Zhong-pei, JINFan

2000, 13(2): 174-178.

[Abstract](1119)

Abstract:
Turbo-codes are produced by parallel concatenation of recursive systemic codes (RSC), and its excellent performances are analyzed based on the free distance and bit error rate of the RSC codes. Adiago- nal interleave method is proposed based on the distance properties ofTurbo codes. With losing little gain, a viterbi decodingmethod to implementTurbo-codes decoding is putforward, withwhichthe correctness ofthe conclusions of this paper is proved by computer simulation.

An Algorithm for Coding of High Digital Audio

WANG Bei-bei, TANGMengGANPing

2000, 13(2): 179-182.

[Abstract](1278)

Abstract:
An enhanced DCTalgorithmwith real-time characteristics is put forward; and a coding algorithm of high quality is obtained by combining the enhanced DCT and a hybrid filter-bank. The proposed coding algorithm improves the adaptability of the filtering transform block length, the filtering properties produced bywhich are more analogous to that of humans’ears.

Prefilter Selection Methods in Fast Algorithm of Discrete Wavelet Transform

HE Zheng-you, DAIXiao-wen, QIANQing-quan

2000, 13(2): 183-187.

[Abstract](1171)

Abstract:
The fast algorithm of discrete wavelet transform (DWT) ensures that the wavelet transform is widely applied in signal processing. In the algorithm, the computation of values on sample space is very important. This paper, based on the discussion of several fast DWT algorithms, is focused in the computation methods of the values on sample space for prefilter selection, includingthewaveletmethod, the directmethod and the sampling function method; at the same time, the corresponding properties of each method are discussed. And then based on wavelet coefficients with minimal norm errors, an optimal design for the prefilter is put forward. The errors of the various methods mentioned above are compared by simulation; the results showthat the proposed optimal method has a fairly good precision in decomposition.

The Effect of Fiber Aspect Ratio on the Mechanical Behavior of Aligned Short Fiber Composites

KANG Guo-zheng, GAO Qing

2000, 13(2): 188-191.

[Abstract](1435)

Abstract:
Based on the single fiber axisymmetrical and three dimensional models of an aligned short fiber reinforced metal matrix composite, the effect of varied fiber aspect ratio on the mechanical behavior of this composite is analyzed by the elasto-plastic finite element method. The studies are focused on the stress transfer, elastic modulus and stress-strain curve of the composite. It is shown that, in this kind of composite, the fiber aspect ratio has an optimum range. The composite with a good performance cannot be obtained with a too small fiber aspect ratio. However, when a critical value is reached, the performance of the composite does not increase with the fiber aspect ratio any more.

An Open Hypermedia CAI System

LIUPing

2000, 13(2): 192-195.

[Abstract](1283)

Abstract:
Based on the discussion of shortcomings of the close CAI, this paper proposes away to create an object-oriented open hypermedia CAI system, and describes the general thoughts, main functional modules and keytechniques of buildingthis open hypermedia CAI systemusingthe object-oriented programdesigning language C++. The design of changeable-assembling media data and the method of linking CAI systems and model-building systems with Windows API interface are expounded in the paper; they have some generality and good practicability.

Optimal Model and Algorithm for Feasibility of Station Arrival-Departure Requirement of Train Operation Plan

ZHAO Qiang

2000, 13(2): 196-200.

[Abstract](1515)

Abstract:
Station arrival-departure capacity is one of the important parts in computer aided making train diagram. In this paper, around trains crossing and overtaking plan, the main reasons that cause the shortage of station arrival-departure capacity on single-track railway are systematically analyzed; a linear 0- 1 optimal model is built for the feasibility of station arrival-departure capacity requirement; and an effective algorithmwith time complexity beingO(n)is given for practical uses. The model coincides well with the general optimization of the train diagram. What’s more, it is helpful in flexibly designing a train algorithm; this is very important to the optimization of a train diagram and can also be used for double and multi-line railways.

Night Vision and Driving Safety of Drivers

JINJian

2000, 13(2): 201-203.

[Abstract](1396)

Abstract:
In this paper, automobile drivers are divided into two groups; one is called accident group every member of which has ever had more than 2 accidents; and the other one is called non-accident group the member of which has never had an accident. The testing method for drivers’night visions is studied, and then a comparison of night vision between 213 drivers in accident group and 652 drivers in non-accident group is carried out. The tested results show that there exists a appreciable difference in night vision between 142 drivers of accident group and 459 drivers of non-accident group (p<0.05). It appears that drivers’night vision disorders are the main cause of traffic accident happenings. Meanwhile, a safety reliability assessment method is proposed for driving at night.

Study on the Random Errors in Markovian Decision-Making Planning

DIAO Ming-bi

2000, 13(2): 204-208.

[Abstract](1304)

Abstract:
Combined with practices, the theories and methods ofMarkovian randomprocess, the creation of transition probabilitymatrix and the calculation of stable state probability are concisely described. Consider- ing that in Markovian decision process, a great number of random factors lead to the distortion of transition probability, and hence producing random errors, the author proposes a newviewpoint, and creates a scien- tific, rational, workable and predicative decision-making technique, which combines Markovian decision- making planningwith sensibility analysis. Besides, by making full use of an example, the author discusses the decision-making process and steps in detail.

On ITS Structure

ZHANGDian-ye

2000, 13(2): 208-211.

[Abstract](1295)

Abstract:
This paper is concernedwiththe theoryof intelligenttransportation system(ITS), and focused on itsmain structure and research contents. In seeking the way to build an ITS structural model, peoples, vehicles, roads and environments are organically united by a technique group to be a traffic system, which runs in good order. So that the traffic efficiency and the traffic safety can be ensured to a great extent, and the environment quality and the energy utilization rate can be improved.

Stochastic Decision Trees

YANGNing, ZHAOLain-wen, GUO Yao-huang

2000, 13(2): 212-215.

[Abstract](1227)

Abstract:
The relationship between the utility value of a decision project and the time spend in a particular state is discussed in this paper. The concept of stochastic decision trees is introduced, and using semi- Markov process theory, the representation of stochastic decision trees is given. Furthermore, the determination of the utility values of stochastic trees is discussed, and the successive formula for calculating the utility values of stochastic trees is presented

A Management Planning Optimal Model for Goods and Materials Enterprises

LI Zong-ping, LIUHai-yan, YEHuai-zhen

2000, 13(2): 216-219.

[Abstract](1438)

Abstract:
Based on the management characteristics of goods and materials enterprises, and through the planning process analysis of management decisions, an optimal model is built for making management plans to process the manifold goods, discounted prices, changeable market demand and management flexibility. The solution to the model is presented, and the adaptability of the model is discussed. Because the model building corresponds with the actual situation of the goods and materials enterprises, it has a directive function for the management of these enterprises.

Statistics Analysis on the Relationship of Highway Net Density with Population Density and Per Capita GNP in National Region

SUNGen-nian

2000, 13(2): 220-223.

[Abstract](1286)

Abstract:
The relationship of the highway net densitywith the population density and per capita GNP in a national region is analyzed by use of the section data of three different times, and it is found that among them there exists a stable mathematical relation and a statistics law. Considering that the highway net building is influenced by the industrial structure of resources, the highway net construction policies and the other transport patterns, a concept of highway dependence-favoritism index is put forward, which is used to explain the variation between the actually obtained highway net densities and the values obtained by model calculation. This study can afford a fundamental theory for the harmony development of national highway network, population and economy.

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2000 Vol. 13, No. 2