西南交通大学学报

Rail Corrugations: Influencing Factors and Retarding Measures

LIUXue-yi, YING Hong

2002, 15(5): 483-487.

[Abstract](1404)

Abstract:
Based on the formation theory of rail corrugations caused by slip-stick vibrations of wheel- sets, an emphatic analysis and summary are made of the influencing factors of corrugations from the aspects of track conditions, bogie structures, contact performances between rail and wheel, and operation conditions. Nine kinds of retarding measures for corrugations are suggested. Some of these measures are tested in field tests, and good results are achieved. Thereby the correctness of the formation theory of rail corrugations and the effectiveness of the retarding measures proposed in this paper are validated to some extent.

Dynamic Performance of Clayey Railroad Subgrade

ZHONG Hui-hong, TANG Kang-min, HUANG Mao-song

2002, 15(5): 488-491.

[Abstract](1439)

Abstract:
A series of tests are conducted in laboratory and field to investigate the behavior of compacted clayey railroad subgrade subjected to repeated loading of to-and-fro trains. Using the test results, the stress-strain behavior of the subgrade was quantitatively studied, and the causes of diseases in subgrade were analyzed. Results show that the accumulated plastic deformation in fill- subgrade produced by the repeated action of trains wheel-set load is closely related to the saturation of subgrade soil. Specifically, the dynamic strength of subgrade soil decreases sharply with the saturation.

Dynamic Design Method for Friction Pile with Prestressed Cable

LIUXiao-li, ZHOU De-pei, YANG Tao

2002, 15(5): 491-495.

[Abstract](1567)

Abstract:
A concept of dynamic design method for friction pile with prestressed cable is put forward. First, the internal forces of the pile and cable are calculated according to the pile s working conditions. Then, the greatest internal forces obtained are taken as criteria to design the pile s structure and the cable s bearing capacity. A discussion on how to determine the prestressed force value is also made. The results of a computing example show that the dynamic design method can reflect the most dangerous state of a pile, thus the friction pile and cable can retain reasonable safety margins, favorable for the cable and pile to work for a long time.

Reliability Analysis of Wing Wall Tunnel Portal

LI Lun-gui, GAO Bo

2002, 15(5): 496-499.

[Abstract](1923)

Abstract:
According to the structure reliability theory and considering the indefinite factors such as the stratum unit weight, the subbase friction coefficient, the base control press stress, the concrete unit weight, etc. a reliability analysis of wing wall tunnel portal structure is made by use of one- order-two-moment method. The computation results show that the computation model is connected with reliability indexes and the reliability indexes meet the requirement on the whole.

Model Test of Two Span High-Strength Concrete Continuous Beams with External Prestress

LI Fang-yuan, ZHAO Ren-da, ZHOU Yi-yun

2002, 15(5): 500-504.

[Abstract](1406)

Abstract:
Four different high-strength concrete continuous beams are designed with different external prestresses and made of different concrete materials (high-strength concrete or steel-fiber- reinforced high-strength concrete), and tested under static load to study their structural behaviors. The test results show that: the crack distribution and propagation of the externally prestressed continuous beams are similar to those of the non-bond prestressed concrete; using steel fiber to improve the cracking load in negative moment region is effective, and the steel fiber reinforcement can not only hinder cracks propagation, but also cause cracks to close after unloading; and conventional reinforcing steel bars are favorable to separating cracks and restricting cracks propagation.

Internal Force Distribution of Nielsen Style X-Style Arch Bridge

TIANXue-min, LI Qiao, ZHANG Qing-hua

2002, 15(5): 505-509.

[Abstract](1602)

Abstract:
A study is made on the distribution regularities of internal forces of Nielsen style concrete-filled steel tubular tied arch bridges under different loads such as distributed force, concentrated force and live load. The results are compared to those of Lohse style arch and parallel rib arch. Model tests are carried out to verify the effectiveness of the theoretical computation. The results show that the design scheme of the model is reasonable and feasible, and the experimental results obtained on the model can accurately reflect the mechanical properties of Nielsen style concrete-filled steel tubular tied arch bridges.

Carrying Capacity and Travelling Speed on Speed-up Single-Track Lines

PENG Qi-yuan, YANHai-feng, YIN Yong

2002, 15(5): 510-514.

[Abstract](1637)

Abstract:
In order to provide a theoretical basis for running speed-up trains on single-track railways in China, an analysis is made of the influence of running speed-up trains on the carrying capacity on speed-up single-track lines. A calculating model for speed-up trains coefficient of deduction is developed. Through numeric analysis and simulation, an important conclusion is drawn out that the passenger trains coefficient of deduction on single-track lines decreases with the increase of running speed. Through analysis of the relationship between the numbers of passing and overtaking behaviors of speed-up trains on single-track lines, a reasonable quantity of speed-up trains to run on single-track lines is worked out, and a general conclusion about the influenceof thequantity and running speed of the speed-up trains on the travelling speed of freight trains on single-track lines is made.

Reasonable Number of Passenger Trains Operated on Single-Track Railway

YANHai-feng, PENG Qi-yuan, LIU Yan-lin

2002, 15(5): 515-519.

[Abstract](1618)

Abstract:
In single-track railway sections, there is a close relationship between the traveling density of passenger trains and their traveling speeds. In this paper, an in-depth analysis is made of the crossing, overtaking behaviors, and traveling speeds of passenger trains on single-track railways, and a general rule reflecting the relationship between the traveling speed and the traveling density is found out. Through a computer simulation, the reasonable scope for the number of passenger trains to be operated on Xiangfan-Huaihua line is obtained. This work can afford a theoretical reference for determining the reasonable number of passenger trains on other single-track railways.

Design of the Assistant Decision System for Train Operation Adjustment

CUI Xian-bo, YANHai-feng

2002, 15(5): 520-525.

[Abstract](1718)

Abstract:
The assistant decision system for train regulation is a key link of train operation adjustment auto-control system. Based on analysis and design of the workflow and components of the system, a mixed 0-1 linear programming model for train operation adjustment is built. Against the disadvantages of the traditional processing method, a finite state policy used for the process control of regulation is taken to improve the performance of process. This scheme is not only in agreement with the basic idea of structured system design, but also easy to realize in software and practicable

Dispatcher s Supervision System with Integrated Positioning Technology on Single-Track Railway

XIANG Dong, GU Yan

2002, 15(5): 526-530.

[Abstract](1391)

Abstract:
The proposed dispatcher s supervision system for single-track railway comprises positioning, communication, map matching functions and some necessary auxiliary functions. Generaly, the positioning of trains on single-track railway can be implemented using a train positioning system integrating GPS, train monitor and transponder. But in plain regions, when there is no need to differentiate the track a train passes through in railway yard and station, the positioning job can be done with GPS only. In the blind areas of signals such as in tunnels, train monitors are workable for positioning. At railway stations, a precise positioning can be realized by means of the existing track circuits for electric interlocking. GSM-R and TETRA systems are advised to transmit the positioning information. GIS electronic maps have been developed according to the one-dimentional characteristic of railways using some simplified algorithms.

A Genetic and Simulated Annealing Algorithm for Optimal Sequential Casing of Less-than-Carload Freights

BU Lei, YIN Chuan-zhong, PU Yun

2002, 15(5): 531-535.

[Abstract](1488)

Abstract:
From the angle of reducing searching region, strengthening convergence and shortening calculating time, the simulated annealing idea is introduced into the genetic algorithm to solve the optimal sequential casing problem of less-than-carload freights in containers. The specific process for realizing the algorithm is expounded, including coding, fitness function calculation, genetic operation, neighborhood selection and temperature reducing methods,etc. Practical numeric calculation shows that the algorithm is superior to the old resolutions.

A Genetic Algorithm Based on Uniform Design Paralleled with Genetic Operation

ZHANG Zhi-yuan, HE Chuan

2002, 15(5): 536-340.

[Abstract](1799)

Abstract:
Simple genetic algorithms have poor stability, for they are prone to premature convergence. In order to overcome this disadvantage, a novel algorithm is proposed using a combination of uniform design and genetic operation. A mapping between the solution space of problems and the search space of the algorithm is established by coding, and then crossover operation, mutation operation and uniform design are performed to produce the next generation of solution candidates for iteration until convergence. The algorithm is tested with a typical testing function, and proved feasible. Compared with the simple genetic algorithms, the algorithm proposed in this paper has a higher precision and a faster convergence rate.

An Algorithm of Joint Adaptive Multi-User Detector

LIU Wei, ZHU Chang-qian

2002, 15(5): 541-543.

[Abstract](1147)

Abstract:
Considering that traditional adaptive multi-user detectors haven t made full use of the character of multi-access signals, a new algorithm of joint adaptive multi-user detection is put forward. In this algorithm, the received signal is used as the reference signal, and the input of adaptive filter changes into the sampled value of each user s spread spectrum serial. Analysis and Simulation results show that this kind of detector has faster convergence rate and better anti near-far impact ability, so it has good potential for practical applications.

Deterministic Interleaver Design for High-Rate Turbo Codes

SHI Zhi-ping, JIN Fan

2002, 15(5): 544-547.

[Abstract](1161)

Abstract:
Interleaver design plays an important role in Turbo code theory, and high-rate turbo codes have some special requirements on interleavers. Based on analysis of five key factors which have influences on the design of interleavers, a study is made on how to design a promising interleaver for turbo codes. Three commonly used mapping functions of deterministic interleavers are discussed, and their odd-even design schemes for high-rate turbo codes are presented. Computer simulation results show that the three odd-even interleavers are easy to realize, and with them, satisfactory performances can be obtained over an additive White Gaussian Noise in high-rate turbo code systems.

Fault Detection of Subway Feed Line by Means of Wavelet Transform

ZHANG Xiu-feng, GOU Shao-bo

2002, 15(5): 548-552.

[Abstract](1408)

Abstract:
A comprehensive analysis is made of the characteristics of the traction current, pickup current and fault current of subways. It is shown that the protection performance caused by differential current increment is mainly determined by the separation effect of current increment, the current change rate di/dtand the checkout precision of every current increment. Since common detection and separation ways have poor anti-interference and unacceptable checkout precision, wavelet transform is used to detect the surge current. Then based on this, the every current increment is extracted out to solve the above problems. Simulation experiments prove that applying wavelet transform to current detection is more practicable and effective than other detecting ways.

Time-Optimal Control Based on Evolutionary Programming

ZHANG Yi, FENG Chun, HUPeng-fei

2002, 15(5): 553-556.

[Abstract](1381)

Abstract:
An evolutionary programming (EP) based method for solving constrained time-optimal control problems is proposed on the basis of an analysis of the advantages and disadvantages of the existing algorithms, and a mathematical model is developed. In this model, the fitness function is constructed by including the constraints in the objective function as penalty terms. A numerical simulation for the problem of linear damped oscillator shows the effectiveness of the method.

Semantic System of Lattice-Valued Propositional Logic Based on Finite Lattice Implication Algebra

MAJun, QIN Ke-yun, XU Yang

2002, 15(5): 557-560.

[Abstract](1185)

Abstract:
With the finite lattice implication algebra being the range of true values of a logic system, a semantic system of lattice-valued propositional logic based on the finite lattice implication algebra is built. Some basic definitions, such as the valuation of the system and the satisfiability of formulas on level A,etc., is discussed. The decidability of effectiveness of the system is proved, and a decision algorithm is presented.

Linear Approximation Algorithm for Bilinear Programming

CHEN Gao-bo, LIUHai-yan, SHANG Sheng-wu

2002, 15(5): 561-564.

[Abstract](1467)

Abstract:
A discussion is made of the optimization of a bilinear programming. The bilinear programming is converted into a max-min problem on the principle of duality, and a linear approximation algorithm for the max-min problem is presented, which proves to be convergent in finite steps. It is also shown that using Karmarkar algorithm to optimize the initial iteration point can make the linear approximation more effective.

Input Resolution on Horn Sets Based on Fuzzy Neural Networks

PEI Zheng, HUANG Tian-min

2002, 15(5): 565-569.

[Abstract](1420)

Abstract:
Resolution principle of automated reasoning has been used in many aspects of artificial intelligence, and many modified methods have been proposed. In the modified methods, input resolution is one of good reasoning methods, and it is complete for Horn sets. Fuzzy neural network is a combination of fuzzy logic and neural networks. In this paper, by using the character of knowledge representation and learning of fuzzy neural networks, input resolution on Horn sets is implemented.

Global Stability Analysis of Neural Networks

ZHANG Ji-ye, DAIHuan-yun, WUPing-bo

2002, 15(5): 570-574.

[Abstract](1609)

Abstract:
An analysis is made of the existence, uniqueness and globally asymptotical stability of the equilibrium point of Hopfield neural networks. Without assuming the boundedness, monotonicity and differentiability of the activation functions, the conditions ensuring existence and uniqueness of the equilibrium are obtained. Using M-matrix theory, Liapunov function is constructed and employed to establish sufficient conditions for global asymptotic stability. These results are applicable to symmetric or nonsymmetric interconnection matrices, and to continuous non-monotonic neuron activation function

Application of Neural Networks in Control of Semi-Active Vehicle Suspension

WANG Yue-ming, ZHANG Wei-hua

2002, 15(5): 575-578.

[Abstract](1594)

Abstract:
In view of the nonlinear characteristics of the semi-active suspension model of vehicles, a study on the application of the adaptive control based on neural networks to semi-active suspension is made. An identifier and a controller with feedforward neural networks are designed, and a specialized learning rule used for the controller is analyzed. The results of simulation show that the ride comfort of a vehicle can be improved by using adaptive control based on neural networks, and the improved BP algorithm used for the neural networks identifier and controller is effective.

Dynamic Performances of Meter-Gauge Passenger Car with Forced-Steering Bogies

LIUHong-you, ZENG Jing, LI Wen-xue

2002, 15(5): 579-583.

[Abstract](1732)

Abstract:
A dynamic model for the meter-gauge passenger car with forced-steering bogies is built, in which some effective treatment methods of the forced-steering mechanism are presented, and the effect of the mechanism parameters of the forced-steering bogies on the dynamic performances of the passenger car is investigated. It is shown that the forced-steering bogies not only improve the critical speed against hunting instability, but also improve the curve negotiating ability of cars

New Optimization Model of Curve Fairness

LIU Ge, LI Bai-lin

2002, 15(5): 584-587.

[Abstract](1781)

Abstract:
Curve fairness is an important issue in CAD/CAM. This paper begins with a discussion of the existing optimization models for curve fairness, followed by design of a novel optimization model for curve fairness with the method of smoothing initial data directly. An evolutionary programming algorithm is presented to solve the optimization problem in curve fairness, with satisfactory results achieved. Theoretical analysis and calculation examples show the effectiveness of the optimization model proposed in this paper for curve fairness.

Demand under the Level of Full Employment: Causes and Countermeasures

LUO Ren-hui

2002, 15(5): 588-592.

[Abstract](1184)

Abstract:
A function for multi-department production is established, and used to analyze the causes of demand under the level of full employment. It comes to a conclusion that demand under the level of full employment is partly due to the supply of economics and partly due to the demand. According to the causes, total supply countermeasures and total demand countermeasures are put forward,i. e., implementing effective financial policies, perfecting social security mechanism, adjusting revenue polices, and increasing exports,etc.

Research on Agricultural Nonpoint Sources Pollution Based on GIS

YU Su-jun, GAO Ping-ping, HE Zheng-wei

2002, 15(5): 593-596.

[Abstract](1402)

Abstract:
A study on agricultural nonpoint source (AGNPS) pollution in Mianyang Guansihe watershed is conducted. The authors have developed a methodology to automatically produce a majority of input data required by an AGNPS model, and to display either all or selected AGNPS output data in GIS files. The specific steps are as follows: (1) data generating: using the remote sensing image processing system and some programs developed by the authors, the data required by the AGNPS model are generated from three sources, including the digital file with contour lines from topographic maps, the digital soil mapping units from soil surveys, and the land cover from landsat TM image classification; (2) data input: once the requires GIS files are generated, a computer program converts the GIS files into the tabular file format requires by AGNPS; (3) model output: all AGNPS output data are converted into GIS files, so that they can be used for further analyses.

The Purification of Alkaline Phosphatase fromEisenia Foetide Sarigng

LI Sui-yan, LI Qing-yi

2002, 15(5): 597-600.

[Abstract](1011)

Abstract:
Alkaline phosphatase (AKP) was purified from the cell extracts ofEisenia Foetida Sarigngusing the routine means: n-bulanol extraction, ammonium sulfate fractional precipitation, DEAE-cellulose chromatography, Sephadex G-100 and Sephadex G-200 gel filtration. The purified AKP was found to be homogeneous by polyacrylamide gel disc electrophoresis. Its specific activity is 40.64 units per milligram of protein, and purification multiple is 57.24-fold.

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2002 Vol. 15, No. 5