西南交通大学学报

Numerical Computation of Pressure Transients During the Crossing of Two Trains in a Tunnel

ZhaoHaiheng, HuangMeirong, Wang Yunshi

1999, 12(2): 127-132.

[Abstract](1870)

Abstract:
A widely applicable calculation method for the prediction of pressure transients during the train crossing in a railway tunnel is proposed based on one dimensional unsteady compressible homentropic flowtheory. Equations of boundary conditions are built formodeling the flowduring the crossing period, and a newgrid system for tracking the motion of trains is proposed. The proposed method is verified by comparing it with the practically measured pressure transients. The characteristics of the pressure transients during train crossing are also discussed.

Traffic Impact Analysis for Large-Scale Public Buildings

Huo Yami

1999, 12(2): 128-132.

[Abstract](1335)

Abstract:
The traffic problem of large-scale public buildings in urban planning is studied. The working process of TIA (traffic impact analysis) of the large-scale public building is given. The scope of traffic impact is determined, and the constitution and forecastingmodel of traffic generation are discussed. Then, the traffic organization pattern of large-scale public buildings is studied. The feasibility and effectiveness of the method are demonstrated with a practical example. Bymeans ofTIA, the impactof sudden increase in traffic volume caused by large-scale public buildings on the local traffic network at this place can be decreased to the minimum.

Numerical Simulation of Longitudinal Ventilation of Long Highway Tunnel

Zhu Bing, Guan Baoshu, ZhengDaofang

1999, 12(2): 133-137.

[Abstract](2258)

Abstract:
With the use of finite element method, the numerical simulation of a tunnel jet ventilation is studied by the two-dimensional incompressible steady Navier-Stokes equation. hence the aerodynamic characteristics of jet ventilation and jet ventilating system with vertical wells are obtained. For different engineering cases, the longitudinal velocity and pressure distributions along the tunnel are given. A comparison between the numerical solutions and experimental results demonstrates the effectiveness and reliability of the numerical solutions.

Numerical Simulation of the Stochastic Process of Railway Track Irregularities

Chen Guo, Zhai Wanming

1999, 12(2): 138-142.

[Abstract](1941)

Abstract:
Several widely-used methods for simulating track irregularities at present are analyzed, and a new algorithm for describing the stochastic process of the railway track irregularities is constructed based on the power spectrum density equivalency in a frequency domain. The magnitude and randomphase ofthe frequencyspectrumare obtained respectively, then the simulation sample in a time domain is achieved through inverse Fourier transform (IFFT). Numerical simulation tests show that the new method is more concise and effective than other methods.

A Study on Variation of the Vertical Rigidity of Turnout along the Longitudinal Direction of Track

WangPing, LiuXueyi, Kou Zhonghou

1999, 12(2): 143-147.

[Abstract](1544)

Abstract:
Mechanical models and calculationmethods for calculatingthe rail support elasticity coefficients of fixed-frog simple turnouts and movable point rail simple turnouts are proposed. Apractical computer program is designed. With the Chinese No.12 fixed-frog and movable point rail speeding-up turnouts of 60 kg/m rail having been analyzed, the variation rule of vertical rigidity of the turnouts along the longitudinal direction of track are exhibited.

Design of a Prestressed Tendon CAD System with Parametric Design Technology

ZhaoHuijuan

1999, 12(2): 148-152.

[Abstract](1376)

Abstract:
In this paper, the basic concept of parametric design technology is described, and the design method of prestressed tendons is analyzed. Then based on the above work, parameterization models for the design of prestressed tendons in longitudinal and sectional directions are established, and the ways of accomplishment of the parametric design in the prestressed tendon CAD system are discussed in detail. Compared with traditional CAD systems, this system is more convenient for designers to express their ideas, and has higher efficiency.

Coupling Vibration Analysis for Long Span Steel Cable- Stayed Bridge Crossing over Yangtze River at Nanjing on Beijing-Shanghai High-Speed Railway

LiXiaozhen, QiangShizhong

1999, 12(2): 153-157.

[Abstract](1759)

Abstract:
With the methods of bridge structural dynamics and vehicle dynamics, regarding high-speed trains and the long span cable-stayed bridge crossing over Yangtze river at Nanjing in Beijing-Shanghai high-speed railway as a combined vibration system, the 3-dimensional coupling vibration responses of the train and bridge are analyzed. The influences of the train speed on bridge deflection, vehicle comfort quality and safety quality are studied. Results show that, though the ratio of deflection-to-span under 0.8 UIC load is 1/600, high speed trains can pass itwith satisfactory safety and comfort.

Damage Detection of Steel Truss Bridge from Changes in Modes of Vibration

Gao Fangqing, Wang Fengqin

1999, 12(2): 158-162.

[Abstract](1525)

Abstract:
The damage in a steel truss model bridge is simulated by changing its element stiffness. The dynamic behaviors of the model bridge are analyzedwithFEMdynamic structural analysis program before and after the model bridge is damaged. It is found that the changes in the mode of vibration are sensitive to the damage degree of elements, and there exists a corresponding relationship between them. A new method for weighting the changes in modes during the structural damage is proposed, inwhich the modes of structural vibration are chosen as weight coefficients. Element damages can be oriented effectivelywith this method.

The Analysis of the Stability of Badu Station Landslide in Nanning-Kunming Railway

ChangJuyou

1999, 12(2): 163-167.

[Abstract](1712)

Abstract:
The landslide of Badu station is introduced briefly. Some measures, such as reducing load, setting up a drainage system and building various kinds of anti-landslide engineerings, etc., are taken to control the landslide. The stability of the administered landslide is analyzed through the running test of trains and apparatus monitoring, with a result showing that the landslide is in a steady state.

A Study on the Vehicle-Guideway Coupling Vibration and Suspension Parameters of Maglev Train

Zeng Youwen, WangShaohua, ZhanKunlun

1999, 12(2): 168-173.

[Abstract](1706)

Abstract:
Based on a vehicle-guideway coupling vibration model of maglev train, the equations of motion are obtained. A simulation program is designed to simulate the vehcile- guideway coupling vibration. The effects of suspension parameters, especially the restraint parameters of module roll, on the dynamic response are analyzed. The limit values of suspension parameters are determined, according towhich, suggestions are given to the design of the testing maglev vehicle of Qingchengshan.

A Study on the Data Structure of Feature-Based Modeling

Xu Ling, ChaiJian, WangJinnuo

1999, 12(2): 174-179.

[Abstract](1210)

Abstract:
In this paper, an interactive technique for the definition of features in geometry feature-based modeling is proposed, and the basic geometric feature is defined with the corresponding data structure. Thus the modeling can be obtained through the addition of one feature to another, and a new graph can be regenerated easily when a group of geometric dimensions is changed.

Development of the Visual System of Locomotive Simulator with Video Compression

ChenHuabin, Zhou Meiyu, He Taijun

1999, 12(2): 180-184.

[Abstract](1554)

Abstract:
The history of the visual system of locomotive simulator is reviewed, with the advantages of the traditional methods analyzed. Based on the distinguishing feature of this system, and through a thorough study on the encoding theory and image sequence, a new thought and concept to design the visual systemof locomotive simulatorwith video compression technique is put forward. The design scheme of the system based on the MPEG-1 standard is introduced in detail, including compression/decoding system, the algorithm of changing the playback speed smoothly based on the analysis of image sequence and the interpolation method between time frame under the situation of low speed. In order to simulate the change of circumstances, a processing method for particular effect is also proposed.

An Encoding Solution and Algorithms for Job-Shop Scheduling Problem with Bottleneck

Huang　Qian, Huang　Hongzhong, Cai　Jianguo

1999, 12(2): 185-189.

[Abstract](1608)

Abstract:
Genetic algorithm is currently one of the most effective methods for solving job-shop scheduling problem. Genetic encoding technique has a deep influence on genetic operation, especially on crossover operation. This paper presents an encoding solution for job-shop scheduling problem with bottlenecks, including algorithms for chromosome representation, chromosome construction and operation sequence generation. A practical encoding example is also presented.

A Study on the Low-Cycle Fatigue Characteristics and Micro-mechanisms of a High-Strength Steel

Zeng Qingxiang, He Guoqiu, Chen Chengshu

1999, 12(2): 190-195.

[Abstract](1401)

Abstract:
The macro-characteristics of cyclic deformation of the high-strength steel 60Si2CrVAunder the condition of low cycle fatigue (LCF) are studied. Based on the TEM observations on the dislocation arrangement of the experimental material during the fatigue process, the micro-behaviors of the dislocations of ferrite and tempered martensite of the high- strength steel are analyzed, and the micro-mechanisms of cyclic softening and hardening are discussed. It is proved to some extent that the cyclic softening and hardening coexist in LCF.

Design of an Intelligent Power Supply for Ultrasonic Generator

Hu Pengfei, Guo Shiming

1999, 12(2): 196-200.

[Abstract](1573)

Abstract:
A type of intelligent high frequency power supply used for power ultrasonic system is designed by use of the timing and counting functions of the INTEL8254, and by use of the computing and controllingfunctions ofthe single-chip computer INTEL8031. This powersupply can automatically trace the resonant frequency of an ultrasonic generator, automatically adjust its power output according to needs, and has an alarm display function.

Analysis of Globe Convergence of Explicit GPC Algorithm Based on State-Space Method

Wang Qian

1999, 12(2): 201-206.

[Abstract](1286)

Abstract:
The global stability and convergence of the explicit GPC (generalized predictive control) based on CARMA model are proved by employing the state-equation, in which the extended least-square method is taken as the identification method. It is shown in theory that the GPC algorithm based on CARMA is better than some currently used self-tuning algorithms such as the generalized minimum-variance method and pole-placement method, and so on, because it has good stability and convergence even underweaker conditions.

nfluence of Radial Electric Fields on Plasma Confinement

WangShiqing, Ren Lang, Gao Qingdi

1999, 12(2): 207-212.

[Abstract](1280)

Abstract:
Radical electric fields may play an important role in L-Htransition. The influence of sheared flows induced by radical electric fields on the confinement of plasma inTokamak is discussed in this paper. A neoclassical ion heat transport coefficient model is adopted, in which the effect of sheared poloidal rotation is taken into account, and the heat flux function has multiple values with the same plasma density and temperature. This model is applied to MHD equations, with the numerical result showingthatthere is a sharp temperature gradient at the plasma edge in the situation ofHmode.

Distinguishing of the Radiating Benefitof Investment Projects

YangJimei, Shi Benshan, Chen She

1999, 12(2): 213-217.

[Abstract](1512)

Abstract:
Investment is an important means by which national economic and social development are promoted. The cost and benefit-distinguishing quality of an investment have direct influences on the appraisal result of an investment project. From the viewpoint of guaranteeing the benefit of thewhole country, by use of a concept of radiating effect, andwith the direct and indirect actions between projects being fully considered, thought and method for distinguishing the cost and benefit of national investment project are presented, with an example applied to a railway construction project. In thismethod, much attention is paid tothe distinguishing of non-economic benefit. It provides an effective benefit distinguishing method for quantitative analyses of construction project appraisal, and it is easy to be practically operated and suitable to be used in the appraisal of national investment projects.

A Fuzzy Assessment Model for the Cost in the Calculation of Loss Caused by Productivity Descending

Zhao Lianwen, Guo Yaohuang, Wang Yaping

1999, 12(2): 218-222.

[Abstract](1595)

Abstract:
The problem of claim for the loss caused by productivity descending in engineering project claims is discussed. By use of the time sequence exponential smoothing principle and method and fuzzymathematical theory, a fuzzy assessmentmethod for cost in the calculation of loss caused by productivity descending is proposed. A fuzzy static assessment model with time factor and a fuzzy dynamical assessment model without time factor are built, with their algorithms discussed.

Application of AHP to the General Planning of Yard and Station of Highway Main Hub

Yan Qipeng, Wang Zhongqiang

1999, 12(2): 223-227.

[Abstract](1382)

Abstract:
The planning of highway network of our country contains the constructions of the main framework of highway, the main channel of water transport, the main hub of harbor- station, and the supporting systemofmodern traffic. In order for the planning and construction of the highway network of our country to be realized on the basis of easy operation and quantitative determination, an alternative model for the general planning of yard and station of main hub of highway is built based on the practical analytic hierarchy process. Furthermore, respective analytic and constitutional methods for quantitative and qualitative matrixes are proposed. In addition, the calculation process and application examples of the alternative model are also presented. Practices show that the methods are feasible. The proposed calculation method is valuable in theory and application for the planning, appraisal of the main hub of highway and for the comparison and selection of related schemes.

The Multiobjective0-1Programming of Transportati on Investment with Fuzzy Coefficient

Zhang Yongjun, Zhou Shuanggui, Du Wen

1999, 12(2): 233-237.

[Abstract](1508)

Abstract:
The transportation system is a complicated economic system, and a transportation investment is a multiobjective decision-making problem. In this paper, based on the transportation investment decision-making problem, a multiobjective 0-1 programming FTIMOLP mathematical model for a transportation investment problemwith fuzzy coefficient is established. Using the fuzzy set theory, the FTIMOLP problem is converted into the solution of the maximal satisfaction level of objective function values relative to the ideal values of decision maker, with the algorithm steps presented. It supplies a basis for transportation investment decision-making.

Design and Production of Multi-Structure Silver Halide Crystallite

QiLinli, Li Zhiming

1999, 12(2): 238-242.

[Abstract](2807)

Abstract:
With the decrease in the size of cubic silver halide crystallites, the resolution of silver halide photographic emulsion increases, meanwhile, its sensitivity decreases rapidly. The structure of silver halide microcystal grains has great influence on the sensitivity. In this paper, the design principle of multi-structure silver bromo-iodide is investigated. Silver halide photographic emulsion with multi-structure grains is precipitated by auto-controlled double jet machine. TEMand XRD analyses showthat iodide-rich layer is composed ofAgBr0.831I0.17, in which iodide is not distributed uniformly and mainly located near the corners of the cubic core grains. XPS analysis shows that the surface of multi-structure grains contains some iodide ions though no iodide has been added, suggestingthatthe iodide ions have the tendencyof diffusing outwards. In addition, the experimental phenomena are explained in theory.

Study on the Purification of Reclaimed Acid with Sedimentation-Absorption Method

Liu Jing, Tong Zhiping, Sheng Caoying

1999, 12(2): 243-248.

[Abstract](897)

Abstract:
Based on the detailed analyses of the characteristics and composition of refined benzene reclaimed acid produced in Pangang coke plant, and based on the comparative study of present purification methods, a new purification method, sedimentation and absorption method, is proposed. The newmethod is easy to operate and its technical process is simple. Also, the reaction condition, dosage and reclamation of the mixed precipitant and absorbent are studied in detail. Experimental results show that pure sulfuric acid used in common industrial productions can be reclaimed with this method, and good economic and environmental benefits can be achieved.

Mean Convergence Criteria for Quasi Hermite-Fejer Interpolating Operator

Wen Chenglin, ZhouXianwei

1999, 12(2): 249-252.

[Abstract](1168)

Abstract:
The mean convergence of quasi Hermite-Fejer interpolation operatorQ2n+1(w, f, x)is studied with the zeros of a kind of Jacobi orthogonal polynomial as interpolation node. Three convergence criteria for discriminating the operatorQ2n+1(w, f, x)converging to f(x)in mean are presented. Their equivalence is proved with cyclic proof.

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1999 Vol. 12, No. 2