西南交通大学学报

Integer Coded Differential Evolution Strategy and Application to Microwave Imaging

LIAO Cheng, WEI Tao, CHEN Wei

2007, 20(6): 647-652.

[Abstract](1640)

Abstract:
Integer coding for a differential evolution strategy was proposed.For an optimization problem,the conventional solution space coded with real numbers is discretized into an integer coded space according to a given precision.Solutions were searched in the integer coded space while the fitness is evaluated in the real space.For engineering problems,the integer coding is efficient,and automatically filters unsteady solutions.As an example,the integer coded differential evolution strategy was applied to solve a microwave imaging problem,which was of discretization,high-dimension and multi-solution.The integer coded differential evolution strategy shows a higher searching speed and obtains better optimization results compared with the real coding.

Text Recovery from EM Leakage of Computers

ZHANG Hongxin, LÜ, Yinghua, HE Pengfei, WANG Haixia

2007, 20(6): 653-658.

[Abstract](1456)

Abstract:
A text receiving and recovery system was designed for EM information leakage from computers.After EM leakage is intercepted by a broad band antenna,band-pass filtered and amplified,the vertical and horizontal synchronization signals are captured by a phase locked loop circuit.The synchronization signals are sampled and processed by an analog-digital converter to get digital video signals.Then,the noises of video signals are filtered using an average filter.At last,the text in the digital video is recovered using a matched filter.An experimental result shows that text can be recovered from EM leakage 12 m away for a Pentium 486 computer with a CRT display,and the signal to noise ratios of the vertical and horizontal synchronization signals are increased by 18.7 dB with the average filter.

Cascade Feature Extraction for Radar Emitter Signals Based on Atomic Decomposition

ZHU Ming, JIN Weidong, HU Laizhao

2007, 20(6): 659-664.

[Abstract](1745)

Abstract:
A cascade feature extraction for radar emitter signals based on atomic decomposition was proposed.Radar emitter signals are decomposed into a linear expansion of atoms by the method of matching pursuit(MP) based on an over-complete dictionary of Gaussian chirplet atoms,and an improved quantum genetic algorithm is applied to reduce the time-complexity of each search step of MP.In this way,optimal chirplet atoms representing features of signals are obtained.Then,the characteristic vectors of atoms are extracted to get strong-discrimination.Experimental results on 5 typical radar emitter signals show that the extracted atoms have good ability to cluster the same radar signals and separate different radar signals,which confirms the validity and feasibility of the proposed approach.

Chaotic Particle Swarm Optimization Algorithm Based on the Essence of Particle Swarm

LIN Chuan, FENG Quanyuan

2007, 20(6): 665-669.

[Abstract](1671)

Abstract:
A chaotic particle swarm optimization(CPSO) algorithm based on the essence of PSO was proposed,following an introduction to the studies on the essence of PSO algorithm.The new algorithm uses chaotic search rather than a random number generator to search a promising region.To increase the diversity,the globally best position in standard PSO algorithm is replaced by the center or weighted mean of the personal best positions of several particles in the same neighborhood.The radius of the chaotic searching region is then adaptively adjusted according to the distance between the personal best position of each particle and the center.Several benchmark functions were simulated with CPSO,and the results were compared with those obtained with some existing PSO algorithms.The comparison verifies the efficiency of CPSO.

Authenticated Group Key Agreement Protocol with Resistance to Leakage of Ephemeral Secret DH Exponents

LI Guomin, HE Dake, LU Xianhui, MA Chunbo

2007, 20(6): 670-674.

[Abstract](1314)

Abstract:
A novel constant-round authenticated group key agreement(AGKA) protocol was proposed to overcome the weakness of the existing common AGKA protocols.The proposed protocol combines the dual exponential challenge-response(DCR) signature and BD structure.It can resist the leakage of ephemeral secret DH exponent attack while retaining the security of the relative AGKA protocols,and is more efficient in terms of both communication and computation.

Design of Variable Structure Control for Mismatched Uncertain Singular Systems

WANG Cuihong, HUANG Tianmin, BAO Xiaoying

2007, 20(6): 675-679.

[Abstract](1394)

Abstract:
The design problem of variable structure control for a class of linear singular system with unmatched uncertainties in the state matrix was studied.The equivalent restrict decomposition form was established for the singular system with mismatched uncertainties.On the basis of this form,the switching surface was designed using the linear matrix inequality(LMI) method,and a variable structure control law,which ensures the system state to reach the switching surface,was presented.A simulation example shows that the design method guaranteed not only the sliding mode of the system state trajectory to be realized,but also the sliding mode to be regular,impulse-free,and asymptotically stable.

Scheme for Naturally Passing Neutral Sections of High Speed Railways

ZHANG Xueyuan, WU Guangning, DENG Mingli, GAO Bo

2007, 20(6): 680-684,690.

[Abstract](1401)

Abstract:
A scheme of naturally passing neutral sections was proposed based on the mechanism of arcing when a train passes the neutral section.In the scheme,a shunt capacitor is connected to both the pantograph and the high voltage winding of the transformer on board.When the locomotive passes the neutral section,there is no arcing because the electric traction system on board has the same potential as that of the catenary.Compared with 3 existing schemes for passing neutral sections,the proposed one is shorter in power-off time,simpler in configuration,and less in investment and maintenance.It also reduces arc intensity significantly when the pantograph bounces on the contact wire.

Chaotic Motion of a Viscoelastic Beam in Time Dependent Temperature Field

LI Yinghui, DU Changcheng, GAO Qing

2007, 20(6): 685-690.

[Abstract](1571)

Abstract:
A nonlinear dynamic model for a viscoelastic beam under a laterally distributed excitation in a time dependent temperature field was derived,which is based on the constitutive description of Kelvin viscoelastic materials,motion equations and strain-displacement relations of a beam with large deflections.One of multiple modes of the governing equation was obtained using Galerkin’s method to obtain a parametrically excited(caused by temperature) Duffing’s oscillator,and the fixed points and homoclinic orbits were obtained according to the Duffing’s oscillator.The critical conditions for chaos of the viscoelastic beam to occur were determined by the Melnikov function method to discuss the path to chaos.The results show that it is possible for the nonlinear viscoelastic beam under the laterally distributed excitation and temperature to enter a chaotic motion in the Smale’s horseshoe sense,and the system experiences many times of subharmonic bifurcations before the chaos happens.

Thermoelastic Flutter of a Two-Dimensional Thin Plate in Supersonic Airflow

CHEN Dalin, YANG Yiren, HU Shaoquan, FAN Chenguang

2007, 20(6): 691-694.

[Abstract](1420)

Abstract:
A nonlinear dynamic model for a two-dimensional thin plate in supersonic or hypersonic airflow was derived using the von-Karman’s geometrical nonlinear strain-displacement relation.In model,the first order piston theory is used to simulate the aerodynamic load.The equations in the model were discretized by the assumption mode method and the Galerkin approach,and solved by the Runge-Kutta numerical method.The results were illustrated by bifurcation and phase-plane diagrams.These results indicate that temperature decreases the stability of the plate,and that as the dynamic pressure increases the motion of the system changes from steady state to periodic state,then to chaotic state.

Steering Behaviors of Coupled Bogie with Independent Wheels

CHI Maoru, ZHANG Weihua, DAI Huanyun

2007, 20(6): 695-700.

[Abstract](1439)

Abstract:
A new design for coupled bogies with Independent wheels was proposed.Theoretical analysis reveals that the bogies have good radial steering ability on a curved track and restoration ability on a tangent track,indicating a prospect to improve the steering performances of ordinary bogies with independent wheels.A dynamic model for the bogies was derived to evaluate the dynamic steering performances,and the simulation results accord with those of theoretical analysis.

Pre-Process Interface Technique for High Level Process Planning

LI Rong, WANG Jinnuo

2007, 20(6): 701-705.

[Abstract](1469)

Abstract:
Following the principle of concurrent engineering(CE),a prototype system of high level process planning(HLPP) was proposed.The complete design information of parts was taken as the data source of the HLPP.It is necessary to develop efficient pre-processors to acquire the design information and transform them into manufacturing data that can be used in process analysis.The pre-processor for extraction of design information,which was programmed with the developing package of UG(Unigraphics),extracts data from conceptual design models.The pre-processor of feature mapping transforms the design data into manufacturing data based on 3D feature recognition and mapping technique.The two pre-processors were integrated into a programming package as pre-process interfaces of HLPP.

Experimental Investigation on Vibrating Compaction Characteristic of Crashed Stone

HE Guangjie, XU Guanghui

2007, 20(6): 706-710.

[Abstract](1347)

Abstract:
A dynamic analysis of vibrating compacting of crashed stone was carried out,and structural resistance of crashed stone in the process of vibrating compacting was measured by utilizing a vibrating compaction test system in order to describe the compaction status of crashed stone accurately.The research results show that change of the compaction status of crashed stone can be described through variation of its structural resistance,while the latter can be expressed by the change in the acceleration response of compacting instrument.The vibrating compaction of crashed stone is a process,and in this process,elastic deformation and plastic deformation occur alternately.Furthermore,the strength,rigidity and stability of crashed stone,as a structure,increase in the form of steps in the whole process.The research result is helpful for the field judgment of compaction status of a crashed stone roadbed.

Finite Element Analysis on Stresses in Slab Track Structures on Soil Subgrade

LUO Zhen, ZHAI Wanming, YAN Hua, YAO Li

2007, 20(6): 711-714,725.

[Abstract](1538)

Abstract:
To analyze the stresses in slab track structures on soil subgrades,a finite element model was derived.The dimensional effects of the reinforced concrete roadbed on the stresses in the track structure was studied.A reduction in the thickness of the reinforced concrete roadbed increases the stresses in it slightly,decreases the maximum compression stresses in the subgrade bed,and has a little influence on the stresses in the slab.An increase in the reinforced concrete roadbed width obviously decreases the maximum stresses in the subgrade bed,but has little effects on the stresses in the slab and roadbed.

Flow Resistance Analysis of Submerged Floating Tunnel

WANG Guangdi, ZHOU Xiaojun, GAO Bo

2007, 20(6): 715-719.

[Abstract](1832)

Abstract:
In order to explore the effects of section shape on pressure distribution,flow field around a submerged floating tunnel for four types of cross section was simulated numerically by using the renormalization group k-ε turbulence model of ANSYS program.Flow field and pressure distribution on the surface of a submerged floating tunnel were analyzed.The results indicate that dynamical pressure has an identical distribution to the same cross section and varies obviously with change in the velocity of ocean stream.Curvature of a submerged floating tunnel is one important parameter influencing the flow field.Ocean stream is separated lately on the surface of a submerged floating tunnel with a streamlined cross section and dynamical pressure on the surface reduces slowly so as to decrease drag force on the surface of submerged floating tunnels with a streamlined cross section.

Creep Model of Rock Subjected to Water Pressure and External Force

WU Xiuyi, LIU Changwu, SHEN Rongxi, YANG Xu

2007, 20(6): 720-725.

[Abstract](1639)

Abstract:
In order to describe the whole process of rock creep and the creep feature of rock subjected to water pressure and external force more exactly,the Burgers model describing the creep feature of rock was modified.A modified Burgers model was set up through paralleling a non-linear adhesion damper and a plastic element,and then connecting in series them and the Burgers model.By analyzing and deducing,a constitutive equation to describe the whole process of rock creep subjected to water pressure and external force was established,and the method to determine parameters in the constitutive equation was given.

Coupled Vibration Analysis of Bridge Deck and Cable of Long-Span Cable-Stayed Bridge

TAN Changjian, ZHU Bing

2007, 20(6): 726-731.

[Abstract](1764)

Abstract:
To investigate the characteristics of coupled vibration of bridge deck and cable of a long-span cable-stayed bridge,a model for the coupled vibration of bridge deck and cable was established,and then,the effects of the frequency ratio of bridge deck to cable,the inclined angle of cable and the mass ratio of bridge deck to cable were respectively analyzed by numerical simulation.The research results show that the resonance occurs not only when the frequency ratio is 1,but also when it is 1/2 and 2.With the increases of the inclined angle and the mass ratio,the resonance amplitude will decrease when the frequency ratio is 1,but it will increase obviously when the frequency ratio is 1/2 and 2.

New Model for Full Process Analysis of Bearing Behavior of Externally Prestressed Concrete Beams

XU Xun, QIANG Shizhong

2007, 20(6): 732-738.

[Abstract](1560)

Abstract:
Based on FEM(finite element method),a numerical model for an externally prestressed concrete beam was proposed by considering the material and geometrical nonlinearities of this structure in order to investigate its behavior at the ultimate state of bearing capacity.In this model,a grid-section model is introduced to determine the sectional tangent stiffness of reinforced concrete beam element and analyze its degeneration process,and three-node friction-sliding tendon elements are employed to analyze the friction and sliding of external tendons at deviators or sliding blocks.Furthermore,major factors affecting the structural behavior,altogether with the axial second-order moment and the second-order effect,are taken into account in this model.The capability and efficiency of the proposed model were verified by comparing the numerical and experimental results of the characteristic parameters,the external prestress increment,the friction-sliding effect and the second-order effect of experimental beams.The research results show that the friction and sliding of external tendons at deviators or sliding blocks are important factors affecting the structural behavior.

Evaluation of GPS Baseline Quality Based on Probabilistic Characteristic of Integer Ambiguity

XU Rui, HUANG Dingfa, LI Chenggang, ZHOU Letao

2007, 20(6): 739-742,747.

[Abstract](1352)

Abstract:
To simplify the evaluation of GPS(global positioning system) baseline quality,a closed-form probability density function(PDF) of fixed GPS baseline solution was presented,and the effects of some factors influencing the PDF of fixed GPS baseline solution,such as the integral region of the PDF,the precision of ambiguity float solution,the precision of baseline float solution and the correlation coefficient of the two solutions,on the improvement of GPS baseline quality were discussed through numerical analyses.The experimental results show that the precisions and correlation coefficient of the ambiguity float solution and the baseline float solution have a great effect on GPS baseline quality,and the precisions of the two solutions have a positive effect on the improvement of GPS baseline quality,while their correlation coefficient has a negative effect.

ANN-Based Prediction of Turning Rate of Traffic Flows at Intersection

LI Ruimin, LU Huapu, SHI Qixin

2007, 20(6): 743-747.

[Abstract](1667)

Abstract:
Based on an improved back-propagation neural network,a predication model for the turning rate of traffic flows at intersections was proposed to predict traffic flows for the signal control of intersections.The corresponding method to determine necessary parameters in this model was given.To improve the learning rate and reliability of neural network algorithms,the self-adaptive learning rate approach and the gradient descent with momentum method were adopted.In addition,a simulation was carried out to prove the correctness of the proposed model.The research result shows that compared with the average value method,the proposed model can decrease the mean absolute relative error by 1%~3%.

Vehicle Routing Based on Floating Car Data

LI Hao, LUO Xia, YAO Chen

2007, 20(6): 748-752,757.

[Abstract](1492)

Abstract:
A floating car information collection system was used to predict section travel time so as to realize the routing optimization of mixed traffic with time windows.A model for the routing optimization of mixed traffic with time windows was set up,and algorithms for floating car map matching and section travel time prediction were proposed to predict section travel time.The results based on floating car data from Chengdu City show that the proposed algorithms are more effective than the present algorithms.With the proposed algorithms,the map matching rate increases by 6%,a higher fitting degree between the predicted and measured values of section travel time is gained,and the total transportation cost decreases by 24%.

Prediction of ESAL Based on Rated Carrying Capacity and Enforcement Intensity

HE Jie, LI Xuhong, HANG Wen, MAO Haijun

2007, 20(6): 753-757.

[Abstract](1361)

Abstract:
A GVWD(gross vehicle weight distribution) model for a typical type of trucks under a non-overloading condition was set up.Furthermore,this model was revised based on the enforcement intensity of overloading to gain a GVWD model based on rated carrying capacity limitation and regulation strength.On the basis of the axle load distribution coefficient and the GVWD model conversions among the same type of trucks,the GVWD model was transformed into an axle load distribution model.Finally,an ESAL(equivalent standard axle load) model was proposed for the same type of trucks by considering the axle load conversion expressions.This ESAL model is different from an ordinary ESAL model—in the proposed ESAL model,the rated carrying capacity limitation and the regulation strength are taken into account,and the GVWD model conversions between reference and target trucks are considered so as to avoid establishing different models for different types of trucks.

Optimization Model for Assignment of Wagon Flows in Railway Network

YAN Hexiang, LIANG Dong, ZHANG Tianwei

2007, 20(6): 758-762,780.

[Abstract](1394)

Abstract:
The current mathematical models for wagon flow routing were amended based on analyzing their limitations and considering the wagon flow reorganization so as to choose the route of wagon flows correctly.Three groups of 0-1 variables were set,and models for choosing the route of wagon flows were proposed on the basis of the concrete practice of Chinese railway to minimize the total cost of wagon flows spent on technical stations and running on railway lines.In the proposed model,the situation that the OD(origin-destination) wagon flow can not be fully assigned is considered,and the defect of ignoring the wagon flow reorganization is overcome to avoid inaccurately choosing the route of wagon flows.As a result,the wagon flow assignment and reorganization corresponding to Chinese reality can be got.

Minimal Determining Set and Its Unique Existence under Independent Decisiveness Condition ⅡA（S2）

GUO Chunxiang, LI Xusheng, GUO Yaohuang

2007, 20(6): 763-768.

[Abstract](1131)

Abstract:
The minimal determining set of social choice function and its unique existence condition were investigated under non-binary choice and the condition that independent decisiveness condition ⅡA(S1) becomes independent decisiveness condition ⅡA(S2).It is proven that the unique minimal determining set and minimal veto set of the choice function exist under the conditions that the choice function satisfies the k-set feasible condition,the unrestricted domain,the Pareto optimality and the independent decisiveness condition ⅡA(S2),and the choice function satisfies the independent decisiveness condition ⅡA(S2) under the above-mentioned conditions if and only if it is oligarchic but not dictatorial.

Quantitative Evaluation Method of Enterprise Cooperation Motivation

LIU Weihua, JI Jianhua

2007, 20(6): 769-774.

[Abstract](1250)

Abstract:
To provide a new approach of research into the cooperation relationship,a quantitative method of calculating enterprise cooperation motivation was put forward based on the balance theory and the expectancy theory.By analyzing the structure of the enterprise cooperation motivation,its calculation procedure was brought out.With the expectancy theory,a model for expectancy motivation was given.Based on the balance theory,methods of calculating balance coefficient,buffer value and amended balance coefficient were given,and a lag model for calculating the amended balance coefficient was built.Three necessary conditions for enterprises taking actions were analyzed,i.e.,the actual balance coefficient,the total buffer value and the amended balance coefficient should be controlled in a certain range.In addition,a calculation model for unbalanced enterprise cooperation motivation was established.On the basis of the above,a method to calculate general enterprise cooperation motivation was given by calculating enterprise external resistance.

Aid Contract-Based Disruption Management in Supply Chain

SHENG Fangzheng, JI Jianhua

2007, 20(6): 775-780.

[Abstract](1512)

Abstract:
By taking a supply chain consisting of one supplier and one retailer as a research object,an aid contract offered by the retailer was used to coordinate the supply chain when the supplier is disrupted.Based on the time sequence of the disruption,a two-stage model was set up for the disruption.The research show that to coordinate the disrupted supply chain,the aid contract must satisfy the following conditions: the partial derivative of aid quantity offered by the retailer to the recovery time of the supplier is the opposite number of retailer’s backorder cost,and the partial derivative of the aid quantity to the supplier’s preventive measures is zero.

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2007 Vol. 20, No. 6