西南交通大学学报

Biological Properties and Spatial Pattern of Oberesfuscipennis

ZHANGJian-qiang

2002, 15(4): 353-356.

[Abstract](1009)

Abstract:
AnOberes fuscipennis(Chevrolat) usually completes a life cycle within one year in Sichuan province and Chongqing, southwest China. It spends thewholewinter in a formof ripe larva. Thereafterthe larva ofO. fuscipennisdevelops to its adult stage. This stage lasts relatively shorter than its larva stage, from the late April (ca20 April) tothe early July (ca10 July), with imagines takingthe veins ofmulberry and other plant leaves as food/nutrition sources, and laying eggs on the tips ofmulberry. The spatial pattern of the eggs shows a negative binomial distribution. The eggs are hatched for eight days and then the new larvae start to eat upwards the young tip of the mulberry leaves near the groovewhere the eggswere laid and hatched. Ashortwhile later, the larvae eat the mulberry leaves downwards for the availability of their food. Often, the larvae also turns upwards to eat the side branches, indicating that they intend to finish up the food source nearby before moving further. The larva stage is the longest period of its life. It can be as long as about tenmonths towards the nextAprilwhen it pupates. The pupa stage lasts about16 days. Duringthis stage theSpilopteron sp.starts to parasitize the larvae ofO. fuscipennis, and the rate of the parasitism can reach up to 37.1 % of the larvae before they start another life cycle.

A Nonlinear Analysis of Long-Span Suspended Arch Bridge

BUYi-zhi, YANGXing-wang

2002, 15(4): 357-361.

[Abstract](1541)

Abstract:
A 3-dimensional compound structural calculation model constructed by beams and rope elements is used to analyze the structural behavior of a certain long-span suspended arch bridge. In the analysis, the structural nonlinearity and ultimate bearing capacityofmembers are considered, and the deformations during construction and the superposition effectof stresses are also taken into account. The emphasis of the study is focused on the nonlinear deformations, internal forces and stability of the bridge during construction and operation. Meanwhile, The distributions of dead and live loads between the cable and arch of the bridge are discussed.

A Shear Lag Analysis for a Simply Supported Steel-Concrete Composite Box Girder

CHENGHai-gen, QIANG Shi-zhong

2002, 15(4): 362-366.

[Abstract](1250)

Abstract:
Adifferential equation for calculatingthe normal stress atthe transverse section of the flange of a steel-concrete composite box girder is derived based on the compatibility of strain and the equilibrium of forces on an micro element of the flange section. Separation of variables is employed to solve the differential equation under the boundary condition of two ends of the girder being simply supported, and the solution of stress is obtained in the form of Fourier series. The shear lag coefficient is then obtained according to its definition. An application example proves the quick convergence and high accuracy of the calculating method presented in this paper, which also shows that satisfactory results are achieved through simple calculations.

A Numerical Method for Simulating Natural Wind Based on Nonstationary Random Process

LUOXiong, LI Yong-le

2002, 15(4): 367-370.

[Abstract](1395)

Abstract:
The second nonstationary random process mathematical model, which is based on data, is the a modification to the first nonstationary random process mathematical model. To build a model of this kind, a nonstationary random process mathematical model is set up through fast Fourier transformation and Herbert transformation based on available original records, and random samples are produced by numerical simulation. As an example, wind speed samples are simulated using the second model based on the observed wind speed records.

Deformation Analysis for Landslide-Tunnel Interaction

MAOJian-qiang, ZHOUDe-pei

2002, 15(4): 371-376.

[Abstract](1432)

Abstract:
Surveys reveal that various damages often occur tomany railway tunnelswhich are constructed in landslides, thus the normal operations of railways are influenced. A finite element method for contact problems is developed to study the interaction mechanism between landslides and tunnels and to analyze the deformation of the tunnels in landslides. The paper begins with a brief introduction to the fundamentals of this computational method, followed by the numerical simulation of an engineering example in which the method is employed to compute the deformation of the tunnels in landslides. The results obtained are useful for understanding the behaviors of the tunnels in landslides and are helpful for the prevention or treatment of the hazards of tunnels.

The Deformation Behavior of Super-Large Pile Group under Vertical Load

XIETao, YUANWen-zhong, ZHUMing

2002, 15(4): 377-381.

[Abstract](1542)

Abstract:
Based on the model testof a super-large pile group undervertical load, the characteristic of load transfer, the bearing behavior, and the lawof variation in side resistance of the pile group are analyzed. It is shown thatunderthe experimental conditions the middle piles are subjected tothe maximumvertical load, and the axial force in the lower partof a pile is largerthan that in the upper part. With the load increasing, the side resistance of a pile comes into play first in the lower part of the pile, and increases progressively from the lower part to the upper part.

Stability Evaluation of Rock Mass Slope with Weak Intercalated Layers

LIUXiao-li, ZHOUDe-pei

2002, 15(4): 382-386.

[Abstract](1398)

Abstract:
The stability evaluation of a rock mass slope with regular weak intercalated layers is discussed. On the basis ofthe plasticity limit analysis, the energy coefficient is proposed to evaluate the stabilityof rock mass slopes using the movable mechanismmethod, with a set of formula derived. The stability of an actual landslide located at the Sichuan-Tibet highway is analyzed using the method proposed in this paper and the traditional limit equilibrium method, respectively. By comparing the results, the evaluation method suggested proves feasible.

Analysis of Bottom Cracks in Asphalt Layers with Geometric Functions and Weight Functions

LUO Rui, HUANGXiao-ming, ZHANGXiao-meng

2002, 15(4): 387-392.

[Abstract](1573)

Abstract:
In order to effectively analyze the crack propagation in asphalt pavements, three geometric functionsF(a/b)for analysis of bottom cracks in asphalt layers are yielded by fitting some discrete values of crack lengths. These discrete values with different ratios of crack lengthato asphalt thicknessbare obtained based on the stress intensity factors calculated by finite elementmethod (FEM) with the crack face being subjectto a uniformstress. The three geometric functions are verified respectively underothertwo sets of loads. The stress intensity factors produced by the three geometric functions according to the theory of weight function are in good agreement with those calculated by FEM in the whole calculation fields. In addition, the weight functions in the whole calculation fields are obtained using the three geometric functions, and a comparison between the weight functions is made

GPS/DR Vehicle Location and Navigation System: A Region Division Approach

LI Cheng-gang, GONGTao, DINGJian-wei

2002, 15(4): 393-398.

[Abstract](1414)

Abstract:
A region division approach for vehicle location and navigation is presented, which is based on GPS technique, dead reckoning (DR) and the map matching of digital road networks. In order to meet the needs ofwide applications, a region-divided model forthe vehicle location and navigation system(VLNS) is established. Based on this model, a systematic analysis of the central module, and an outline design of the VLNS are discussed on the following issues: (1) the dynamic switch of the workingmode between GPS and CDGPS (conventional differential GPS), (2) the layered map database and the dynamic compile of the layered map, and (3) the improved map matching algorithm that compensates the positioning errors of GPS and dead reckoningwith the aid of digital map. It has been proved thatwith the region division approach, the performances of the VLNSget improved. The VLNSmodel built in this paper can provide high precision application not only for local-area, but also forwide-area users

A Local Adjustment Algorithm for Inserting Constrained Segments in Delaunay Triangulation

SONG Zhan-feng, ZHANZhen-yan, PUHao

2002, 15(4): 399-403.

[Abstract](1427)

Abstract:
An algorithm for constructing constrained Delaunay triangulation (CDT) is presented. First, the Delaunay triangulation for constrained data sets is constructed. Then, by inserting constrained segments into the Delaunay triangulation, a local adjustment ismade to its impact area on the maximumangle principle on the condition that the basic properties of CDT are satisfied. Meanwhile, the process of inserting the constrained segments into CDTis expounded in detail, and the updatingmethod for the topological relations in CDTis presented. Finally, the time efficiency of the algorithmproposed is analyzed. It is shown that the algorithm has a high efficiency and a stable operation.

Nonlinear System Identification with Recurrent Neural Network Based on Genetic Algorithm

FENGHao, HEHong-yun, MI Zu-qiang

2002, 15(4): 404-407.

[Abstract](1784)

Abstract:
An internal time-delay recurrent neural network (RNN) is used for identification of nonlinear dynamic systems, and its dynamic equations are described. As a learning algorithm, an improved genetic algorithm is applied to train the RNN. Two identification simulation examples for nonlinear dynamic SISO and MIMO plants validate the efficiency of the internal time-delay RNN and the improved GA.

A Secure and Efficient Conference Key Distribution Scheme

YUANDing, FANPing-zhi

2002, 15(4): 408-412.

[Abstract](1361)

Abstract:
A security flaw in the conference distribution scheme, namely GDH.2, proposed byM. Steiner et al, is found out, and a new secure and efficient conference key distribution scheme suitable for users exchanging information on insecure communication networks. Compared with GDH.2, the security of this new scheme is greatly improved at the cost of a slight increase in computation and communication loads.

Simulation Study on the Control Systems of Mechanical Braking of Maglev Trains

ZHANGXiang, ZHANGKun-lun, LIANJi-san

2002, 15(4): 412-416.

[Abstract](1424)

Abstract:
An analysis is made of the mechanical braking control systems of EMS maglev trains. A mathematical model for the mechanical braking system is built, on the basis ofwhich a comparison between the several control modes of the mechanical braking system is made. Simulation results show that the adaptive control mode based on PI regulation is better than the PI regulation and conforms to the specifications of brake.

Spatial Correction of the Distorted License Plate Image of Automobiles

HAO Yong-jie, LIUWen-yao, LUShuo

2002, 15(4): 417-420.

[Abstract](1328)

Abstract:
According to the general style of automobile license plates in China, a method based on Hough transformation is proposed to acquire the parameters of four borders of the license plates. The coordinates of the four vertices of the quadrilateral plate are obtained, and away to performHough transformation for lines in the polar coordinate system is also presented in detail. Then, the bilinear spatial transformation equations are solved according to the mapping between the four vertices of a distorted plate image and its normalized vertices, so as to correct the distorted plate image. Finally some smoothing procedures are used to erase the burrs of characters in the plate image. Experimentresults showthatwiththe method introduced in this paper the distorted license plate images can be well normalized.

Experimental Study on Exhaust Emission of Diesel Engine under Steady Operating Conditions

ZHOUBin, LI Yu-mei, WANG Guo-qua

2002, 15(4): 421-424.

[Abstract](1182)

Abstract:
The emission of a diesel engine differs in different operating conditions. The exhaust emission properties of diesel engines 6135ZG under steady operating conditions are studied experimentally, with its load-emission behaviors, contour emission line, and a 13-mode emission graph presented. This study is to provide a basis for optimization of the operating parameters and reduction of the exhaust emission of diesel engines.

A Tilting Monitoring System of Tilting Train Based on Single Axis Gyroscope Platform

WANGXue-mei, NI Wen-bo

2002, 15(4): 425-429.

[Abstract](1604)

Abstract:
A tilting monitoring system for tilting trains which is based on single-axis gyroscope platform is presented, and its working principle and application to the tiltingmonitoring of tilting trains are analyzed in detail. Meanwhile, an in-depth error analysis of the platform system reveals that the excursion of gyroscope and the zero offset of accelerometer are the main factors influencing the working precision of the system.

Prediction Model and Program Design for Transportation Quantity of Postal Trucks

YANG Wei

2002, 15(4): 430-433.

[Abstract](1418)

Abstract:
An introduction is made to the method and techniques of calculating the post transportation quantity and load turnover when a computer management information system is applied to the postal transportation. Using the Winter multiplication method, a prediction model for transportation quantity is built for provincial postal transportation enterprises. Then, a study of the self-adapting correction technique of this model is made fromthe aspect of practical application. Finally, the kernels of software design of the prediction model are described, with a flow process diagram and a computational example presented.

Rational Number of Arrival and Departure Tracks in Passing Stations Along Single-Track Railway

YANHai-feng, PENG Qi-yuan, BAO Wei-min

2002, 15(4): 434-438.

[Abstract](1600)

Abstract:
There exists randomicity in the crossing and overtaking behaviors of trains on single-track railways. The number and patterns ofthe crossing and overtakingoftrains in various operation conditions are studied by probabilistic analysis. The relationships between the number of arrival and departure tracks and the crossingorovertakingnumber and patterns are obtained. The main factors thathave a direct influence on the number of tracks is found out, and the variation rules of these factors versus the track number are presented. The results obtained have been used to analyze the number of tracks on Chongqing-Huaihua railway.

Sensitivity Analysis of Equilibrium Network Flow

LIUHai-yan, SUNHong, DUWen

2002, 15(4): 439-442.

[Abstract](1259)

Abstract:
Equilibrium network flows are not necessarily unique, and this nature creates difficulties in the sensitivity analysis of network related phenomena. In this paper, a minimum distance approach is proposed for the sensitivity analysis of equilibrium network flow. With this method, the solution space of paths is transformed into a set of solution spaces of path sections, in which the sensitivity is then discussed. Thus, the problem of nonuniqueness can be avoided.

A Heuristic Layout Restriction Algorithm for Solving Two-Dimensional Rectangular Layout Loading Problems

LIBing, YEHuai-zhen

2002, 15(4): 443-447.

[Abstract](1129)

Abstract:
Based on an analysis ofthe loading problemswithtwo-dimensional rectangular layout, a heuristic algorithmfor the novel two-dimensional rectangular layout devised in this paper is proposed by means of setting layout restraint conditions for the loading problems. Experimental results show that the optimum or quasi-optimum solution to the problems of this kind can be obtained with the algorithm proposed in this paper.

Fuzzy Comprehensive Evaluation of Engineering Contracts

LIXiao-long, FUQiang, WUZhen-ye

2002, 15(4): 448-453.

[Abstract](1306)

Abstract:
Evaluation of the execution of contracts is important in engineering construction supervision. This paper begins with an investigation on the features of engineering contracts, followed by an analysis of the engineering contracts using analytic hierarchy process (AHP). Then, a fuzzymathematical model is builtfor evaluating engineering construction contracts, with a method and a practical model for the construction evaluation and hierarchical evaluation of engineering contracts presented. Finally, the operation significance of the model proposed in this paper is verified with an example.

Tactic Study on Proportional Sale of State-Owned Shares at Floating Prices for Their Circulation

CHENShe, WUYi-bin, WUJing-ye

2002, 15(4): 454-458.

[Abstract](983)

Abstract:
The kernel problem of state-owned shares’reduction lies in how to price the shares, while the kernel problem of their circulation lies in the capital sustainability of a securities market. The reduction of state-owned shares is concerned with the steady development of the security market and the equity of the social resources reallocation. Based on market mechanism, a tactic is put forward for proportional sale of state-owned shares through floating pricing. The operational practicability of the state-owned shares’ reduction and circulation is analyzed, with some relevant suggestions given to the specific circulation mode of the state-owned shares that are allowed into the circulation market on the condition that the state gives up its shares-holding authority.

An Extended Model and a Generalized Algorithm for a Job Scheduling Problem in Production Management

WANGMeng-lan, HUANGTian-min

2002, 15(4): 459-462.

[Abstract](1493)

Abstract:
A discussion of the job scheduling problem of assigningnparts to be processed tom machines is made. Withmachines allowed to be idle and a idea of load introduced, where loadmeans the maximum of parts processed by each machine, an extended model and a generalized algorithm are obtained without the constraint ofm≤n.The results of an example prove the effectiveness of the model and algorithm proposed in this paper.

A Decision Model for Product Scheme Evaluation Based on AHP and Degree of Gray Incidence

SONGJiu-peng, DONGDa-wei, GAO Guo-an

2002, 15(4): 463-466.

[Abstract](1473)

Abstract:
Considering the complexity of multi-objective decision of product scheme design, an evaluation system for product schemes is built, and the standardization of its evaluating indicators is made. Based on this, a multi-objective decision model is then built by using the analytic hierarchy process (AHP) to determine the weights of the evaluating indicators and by taking the degree of gray incidence as the evaluation criteria.

A Hidden Markov Decision Model

ZHAOLian-wen, WUXiao-xiong, GUO Yao-huang

2002, 15(4): 467-469.

[Abstract](1240)

Abstract:
A discussion is made of the relationship between the unobservable status and sample value of Markov decision processes. With a definition of error-avoiding characteristic function introduced, a hidden Markov decision model is built by using the structure of hidden Markov processes and Markov decision models. The status estimation and the stage income function are also discussed.

The Construction and Convergence of Ishikawa Iteration for Quasi-Nonexpansive Operator Sequence

HUANGJia-lin

2002, 15(4): 470-472.

[Abstract](1024)

Abstract:
A study is made on the fixed points of the quasi-nonexpansive operator sequence with a mapping from the bounded closed convex subset of a uniformly convex Banach space into the closed convex subset in the same space. The sufficient conditions for the quasi-nonexpansive operator sequence to have a common fixed point are obtained, and the corresponding Ishikawa iterative sequence converging on the common fixed point is constructed. The results obtained in this paper are the extension of the conclusions in the recent publication of the author.

The Eigenvalues of Unsymmetric Tridiagonal Matrices

FENGTian-xiang, TANMing-shu

2002, 15(4): 473-476.

[Abstract](1157)

Abstract:
First, an unsymmetric tridiagonal matrixTis transformed into a symmetric tridiagonal matrix T*. Then, with the symmetric tridiagonal matrixT*and a displacementσgiven, an algorithm of solving for the simplified matrixT^from the matrixT*is presented. Thus, the eigenvalues of the symmetric tridiagonal matrix are obtained byQRmethod with Wilkinson displacement. The concrete algorithm is easy to implement on computers.

A Note on the Fuzzy Filters of Lattice Implication Algebras

ZHAO Guang-feng, XUYang, SONG Zhen-ming

2002, 15(4): 477-481.

[Abstract](1143)

Abstract:
The properties of the fuzzy filters of lattice implication algebras are further studied on the basis of the structures of lattice implication algebra. It is shown that a family of congruence relations can be induced by a fuzzy filter of lattice implication algebra. The algebraic structure of this family of congruence relations, along with the homomorphism mapping between the quotient lattice implication algebras induced by the congruence relations, is also studied

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2002 Vol. 15, No. 4