西南交通大学学报

Packet-Based Call Admission Control Scheme in Broadband CDMA Networks

FANG Xuming, ZHU Longjie, ZHANG Dandan

2007, 20(1): 1-7.

[Abstract](1306)

Abstract:
A cooperative CAC(call admission control) mechanism for user connection access control and user packet access control,and an improved priority-based CAC scheme were proposed,in which modeling for three major types of traffic,i.e.voice,video and data,were elaborated for application in broadband CDMA(code division multiple access) networks.The scheme takes the packet in wireless packet networks as the minimum resource management unit,incorporates the residual capacity and the traffic characteristics,and sets different access criteria for different types of traffic.The connections and packets with higher real-time demands are given higher accessing priority,while guaranteeing reasonable quality of service for the lower real-time demand traffic.Simulation results show that,with the proposed CAC scheme,the traffic blocking probability and average access delay are efficiently reduced,and the resource utilization efficiency is increased.

Nonrepudiable Threshold Proxy Signature Scheme Based on Elliptic Curve Cryptography

YUAN Ding, FAN Pingzhi

2007, 20(1): 8-12.

[Abstract](1407)

Abstract:
An improved threshold proxy signature scheme was proposed to overcome the defects of the existing scheme that it can not resist conspiracy attacks and forgery attacks from the signers,and is not practical in some applications.In the signing process,every actual signer is required to put in his private key,which makes the signature contain secret information of both proxy signers and actual singers and resist conspiracy attacks and forgery attacks from the signers.An elliptic curve cryptography was used to replace ElGamal discrete logarithm cryptography in the original scheme,which makes the new scheme efficient.

Feature Vector-Based Nude Picture Detection

PENG Qiang, ZHANG Xiaofei

2007, 20(1): 13-18.

[Abstract](1463)

Abstract:
To overcome the shortcomings in the existing nude picture filtering systems and image recognition techniques,a feature vector-based nude picture detection algorithm was proposed.In the algorithm,chrominance value of the YIQ color coordinate and hue value of the YUV color coordinate were taken to build the skin color model,and the SSD(sum of square difference)on a 5×5 pixel window is used as the skin texture model.Then features representing the number and proportion of skin areas are extracted from skin mask images and are consequently inputted into an SVM(support vector machine).The experimental results on databases containing 457 nude pictures and 1 101 non-nude pictures show that the proposed algorithm averagely achieves 89.3% in detection accuracy,85.8% in retrieval rate,and 4.4% in error rate.

Image Sparse Decomposition Based on Quantum Genetic Algorithm

LI Hengjian, YIN Zhongke, WANG Jianying

2007, 20(1): 19-23.

[Abstract](1745)

Abstract:
Based on the quantum genetic!algorithm(QGA)and the matching pursuit(MP),a fast image sparse decomposition algorithm was put forward to reduce the amount of calculation.QGA combining the genetic algorithm and the quantum information theory has a large search space with small population and a good global search capability,while image sparse decomposition based on MP is an optimal problem,so it can be fast solved by QGA.Simulation results show that the number of inner product between the image or its residual image and atoms is only 4 000 times in each calculaltion step,and the reconstructed image has fine visual quality.

Color Calibration Based on KPCA and ANFIS

DING Errui, ZENG Ping, WANG Yifeng

2007, 20(1): 24-28.

[Abstract](1314)

Abstract:
An algorithm for color calibration was proposed by integrating an ANFIS(adaptive-network-based fuzzy inference system) with KPCA(kernel principal component analysis).The algorithm maps the input data into a higher dimensional feature space with a kernel function first,then extracts principal components of the mapped data by the PCA,and finally implements color calibration by the ANFIS.Experimental results indicate that the proposed algorithm is feasible and effective,and is superior to the conventional ANFIS in both precision and robustness.The average error,maximum error and the error standard deviation regarding the test data(training data) decrease by 37%(45%),34%(40%) and 35%(40%),respectively.

Output Feedback Control for Distributed Network Control System

ZHANG Xiang, XIAO Jian

2007, 20(1): 29-34.

[Abstract](1421)

Abstract:
A mathematical model was proposed for a linear distributed network control system with delays in forward and feedback channels,and it was used to transform the system into a linear system with time-varying delays in state and control input.A robust H-infinity control scheme of output feedback based on an algebraic Riccati equation was presented to stabilize the closed loop system.Results of a simulation example show that the state of the system reaches 0 at t=2.5 s,indicating a quick response to zero state.As an example,a design of a robust H-infinity controller for output feedback was presented.

Influences of Planar Pattern on Performances of RFIC Spiral Inductors

XIAO Huaqing, XIONG Xiangzheng, LIAO Cheng

2007, 20(1): 35-39.

[Abstract](1548)

Abstract:
The performances of RF(radio frequency) integrated circuit(RFIC) spiral inductors on silicon(SIOS) with different planar structures were simulated based on a typical physical model using the HFSS(high frequency structure simulator).The simulated results are well coincident with those from theoretical analysis.Compared with those of the quadrilateral and octagonal ones with the same inner radius,the maximum quality factor Q of the circular spiral inductor increases by 0.90 and 0.80 times,respectively;at the frequency corresponding to the maximum quality factor the reflection coefficient of the circular spiral inductor decreases by about 32.5% and 26.6%,respectively,and the masses of metals used decrease by about 30% and 20%,respectively;and the band width of the circular spiral inductor is about 60% and 30% wider,respectively,for Q5.

UWB Antenna Optimization Using Micro-genetic Algorithm

QIN Yanmimg, LIAO Cheng, WEI Tao

2007, 20(1): 40-43.

[Abstract](1689)

Abstract:
To meet different designing requirements and improve the efficiency of antenna design,a new method,finite-difference time-domain method(FDTD) combined with a micro-genetic algorithm(MGA),was proposed for design of ultra-wide band(UWB) antennae.An analysis shows that MGA makes an optimization converges faster than a genetic algorithm(GA) does.As an example,a TEM horn antenna was analyzed to show the feasibility of the new method.The processes of the radiation in the parallel-plate transmission line and in the TEM horn antenna were obtained with FDTD,where an UWB electromagnetic pulse was fed through a coaxial transmission line.The information about the antenna in time domain was also acquired.The performance parameters were calculated based on the acquired information,and followed by normalization.The normalized performance parameters were used to set up a fitness function,and the physical structure of the antenna was then optimized with the MGA.

Accurate Nonlinear Analysis of Tower and Cable in Construction of Main Cable for Suspension Bridge

CHEN Changsong, SU Long, YAN Donghuang

2007, 20(1): 44-48.

[Abstract](1748)

Abstract:
To analyze the deformation og main cable of a suspension bridge accurately,changes in the deformation of main cable shape and force action on tower in the construction were analyzed based on the principle of multi-span catenary of main cable.Action of tower on cable saddle was simulated as a nonlinear spring with a beam-column effect considered in calculation of tower stiffness.Two formulas were derived both for nonlinear thrusting rigidity and moment of tower bottom.Based on the free state of main cable,the construction of cable strands for a suspension bridge with a main span of 1 280 m was researched,and unequilibrium force acting on tower by cable,horizontal displacement of tower top,and moment of tower bottom were calculated and analyzed.The research results indicate that the effect of beam-column is little during the construction.

Fatigue Test of Tensile Anchor Plates in Cable-Beam Anchorage Zones for Zhanjiang Gulf Bridge

REN Weiping, QIANG Shizhong, WEI Xing, WANG Chunhan

2007, 20(1): 49-54.

[Abstract](1578)

Abstract:
In order to assess the fatigue performance of the key connection details of tensile anchor plates in cable-beam anchorage zones,a full-scale model fatigue test of the tensile anchor plates of Zhanjiang gulf bridge was conducted.ANSYS,a finite element software,was used to analyze the structural behavior to guide the fatigue test.The analysis and test results show that the concentration of stresses at the end of fillet welds between the tensile anchor plate and the tensile anchor tube is obvious,and the maximum principal tensile stress occurs in the stress concentration region.In addition,no fatigue cracks were found in the test under the condition of the fatigue load designed.This shows that the fatigue life of these connection details can satisfy the design requirement.

Fast Algorithm for Stationary Stochastic Response Subjected to Multi-component Multi-support Seismic Excitation

ZHAO Canhui, ZHOU Zhixiang

2007, 20(1): 55-60.

[Abstract](1612)

Abstract:
To calculate the stationary stochastic response of a long-span bridge subjected to multi-component and multi-support seismic excitation,a pseudo-excitation method was proposed based on the single-component pseudo-excitation method.Theoretic analyses show that this pseudo-excitation method has the same accuracy as the classic stochastic vibration method,but calculation rate of the former is 10 times faster than that of the latter,and the traveling wave effect and partial correlation effect can be included easily.

Primary Resonance of Thin Rectangular Plate with Material Nonlinearity on Winkler Foundation

YANG Zhian, HAN Yanbin

2007, 20(1): 61-65.

[Abstract](1444)

Abstract:
Based on the elastic theory,nonlinear dynamical equations for an externally excited thin rectangular plate on the Winkler foundation were established by considering meterial nonlinearity in order to investigate its nonlinear vibration,and the corresponding nonlinear vibration equation was obtained using the Galerkin’s method.By means of the method of multiple scales for nonlinear oscillations,the approximate solution of primary resonance of the system was acquired,and a numerical analysis was carried out.The research shows that jump and hysteresis phenomena exist in the amplitude-frequency response curves with the changing of damping factor,geometric parameters and excitation,the amplitude decreases with the increase of damping.In addition,the amplitude-frequency response equation was investigated,and the transition variety and bifurcation diagram of unfolding parameter plane were obtained based on the singularity theory.

Change in Microstructure of Salty Soil during Crystallization

WANG Chunlei, JIANG Chongxi, XIE Qiang, FENG Tao

2007, 20(1): 66-69.

[Abstract](1317)

Abstract:
The microstructure of salty soil was investigated by using environmental scanning electron microscopy and X-ray energy-dispersion spectroscopy(EDX),and the effects of crystallization on strength of salty soil was discussed to open out mechanism of the effect.In addition,the effects of change in the microstructure on soil strength were researched.The research results show that the microstructure of salty soil is obviously different before and after crystallization.It is a soil aggregate structure wrapped by a mixture of salt and soil before crystallization,while a blending structure of crystal and soil to significantly enhance the strength of salty soil.

Effect of Nano-SiO2 on Performance of Concrete in Dissolving/Crystalling Cycles of Salts

LI Guhua, GAO Bo

2007, 20(1): 70-74.

[Abstract](1298)

Abstract:
To improve the performances of concrete in sea water or soil with inorganic salts,the performance of concrete with nano-SiO2 in dissolving/crystalling cycle of salts was investigated by the experiment of concrete strength,and the microstructure of concrete was analyzed with SEM(scanning electron microscope) and XRD(X-ray diffraction).The result shows that nano-SiO2 can improve the performances of concrete.By considering the performance of concrete and its construction cost,the optimum mass fraction of nano-SiO2 is 1%.Compared with normal concrete,modulus ratio and special modulus ratio of the concrete with 1%(mass fraction) nano-SiO2 in dissolving/crystalling cycle of salts increase by respectively 11% and 20% after 110 cycles.The analysis of the microstructure shows that nano-SiO2 can improve interface structure between cement and aggregate,and decrease the content of Ca(OH)2 in concrete.

Kinematic Orbit Determination of Low-Earth Orbiters Based on GPS Precise Point Positioning Technique

HAN Baomin, YANG Yuanxi

2007, 20(1): 75-79.

[Abstract](1434)

Abstract:
In order to advance orbiting results obtained using the present kinematic orbit determination method,the principle and mathematic model of kinematic orbit determination based on GPS PPP(precise point positioning) technique considering dynamic information on a low-earth-orbiter(LEO) were analyzed.By using smoothed orbiting result as the priori orbit of an LEO,an improved majority voting method was proposed and successfully used in kinematic orbit determination.With this proposed method,the quality of data pre-processing based on undifferenced observations from an onboard GPS receiver can be improved and big phase breaks causing many gaps in the orbit of an LEO can be avoided efficiently,as a result,orbiting accuracy can be enhanced.

Architecture of Collaborative Design System

LI Bailin, HE Gang

2007, 20(1): 80-83.

[Abstract](1536)

Abstract:
To develop a model for building a collaborative design system to meet the requirment of enterprises,the characteristics of collaborative design and the requirement of enterprises for collaborative design were analyzed,and the architecture of a collaborative design system was researched from three hierarchies of enterprises,an enterprise itself and software system.Based on the above analysis and research,a architecture of collaborative design systems was developed.Because of the process of cheching the data processing and so on,this architecture has the function of security and secrecy.A proprototype of collaborative design systems has been developed based on the architecture.

Improvement of Dynamic Performance of Speed-Raising Locomotive with Motor Mounted on Frame

MA Weihua, LUO Shihui, SONG Rongrong

2007, 20(1): 84-88.

[Abstract](1554)

Abstract:
To improve the lateral dynamic performance of a speed-raising locomotive running at a high speed,the lateral stability,ride index,lateral wheelset force and change in wheel load for a traction motor respectively elastically and rigidly mounted on the frame were compared and investigated based on analyzing the traction motor suspension designs of 2C0 speed-raising locomotives.The result shows that when a motor is elastically mounted on the frame,all performances of a locomotive running at a high speed on a straight track are improved in some degree,and its dynamic performances become less sensitive to suspension parameters so as to keep the stable dynamic performance of a locomotive in long-time running.

Bending Vibration Analysis of Composite Transmission Shaft

XU Zhaotang, ZHU Rupeng

2007, 20(1): 89-93.

[Abstract](1502)

Abstract:
To improve the dynamic characteristics of a helicopter transmission shaft,bending vibration of a composite transmission shaft was investigated under a non-inertial system.Based on theorem of the motion for center of mass,a bending vibration equation for a tilting fiber composite transmission shaft with two supports was derived under a non-inertial system,and its solution was obtained by the Galerkin method.The effects of eccentric mass,damping,inertia force and gravity on the vibration amplitude were analyzed.The results show that a fiber composite transmission shaft has a larger bending natural frequency than a steel or aluminum alloy transmission shaft and a larger frequency range of non-resonance between adjacent orders,smaller static deflection and amplitude.When inertia force of a transmission shaft does not change,its maximum transversal displacement is equal to the sum of the static deflection produced by inertia force and gravity and the amplitude of deflection induced by eccentric mass,and when inertia force of a transmission shaft changes,dynamic deflection is produced.

Particle Swarm Optimization Algorithm for Topological Optimization of Truss Structures

YUAN Dailin, CHEN Qiu

2007, 20(1): 94-98.

[Abstract](1593)

Abstract:
To solve the problem of topological optimization of truss structures with stress and displacement constraints,particle swarm optimization(PSO) algorithm was adopted.With this method,the penalty function approach is applied to turn the constrained optimization problem to a no-constrained optimization problem,and then the particle swarm optimization algorithm is used to iterative calculation.Two examples of topological optimization of truss structures with stress and displacement constraints were given to show the validity of this method.The results indicate that the identical results are got by PSO and another topological optimization algorithm.

Constitutive Model for Cyclic Softening Behavior of 45 Steel under Uniaxial Cyclic Straining

LUO Yan, YANG Xianjie, GAO Qing

2007, 20(1): 99-103.

[Abstract](1396)

Abstract:
In order to describe the cyclic softening behavior of materials more exactly,a cyclic plastic constitutive model was proposed based on the deformation character of quenched-tempered 45 carbon steel under symmetrical and unsymmetrical cyclic loadings.In this model,strain softening after the upper yield stress in the first 1/4 cycle is taken into account.In addition,the subsequent cyclic softening behavior was simulated by utilizing the evolution equations of yield radius and backstress.The research results show that the predicted results agree well with the experimental ones for the shape of cyclic softening hysteresis loops and the evolution of stress amplitude with cyclic number during the low cycle fatigue.

Multi-level Fuzzy Evaluation Method for Civil Aviation System Safety

MA Guozhong, MI Wenyong, LIU Xiaodong

2007, 20(1): 104-109.

[Abstract](2084)

Abstract:
An index system was proposed for safety assessment of civil aviation systems.Fuzzy comprehensive evaluation method was used to calculate the safety degrees corresponding to management and to the human-machine-environment system composed of flight,support and maintenance subsystems.The comprehensive safety degree was obtained based on the above degrees,and divided into 5 grades.The system is not safe enough if the comprehensive safety degree is under grade 4.A further evaluation to the data can reveal the possible hints that cause the data to be evaluated as "bad" or "very bad",so that precautions can be taken accordingly.

Modeling Method for Road Guide Signs Based on Intersection Features

HUANG Min, YU Zhi, ZHANG Xiaolan

2007, 20(1): 110-114.

[Abstract](1279)

Abstract:
The content of road guide signs was categorized into guide sign items,which were further classified into 3 categories: state signs,connection signs and direction signs.The state function set for the guide sign items was defined based on the road network topology.The key of road guide sign modeling is to indicate the characteristic of intersections.In the proposed modeling method,the state function set for the guide sign items is determined through calculation of the feature functions of intersections.As an example,a connection guide sign on an actual urban road network was obtained with the proposed method.

Travel Time Reliability Based Traffic Assignment Model with Multiple User Classes

CHEN Jianlin, LIU Haixu, CHENG Xueqing, PU Yun

2007, 20(1): 115-119.

[Abstract](1627)

Abstract:
The uncertainty in travel time caused by stochastic factors was analyzed.It was assumed that a traveler’s decision on route choice is a tradeoff between expected travel time and travel time reliability.The route choice behaviors were grouped into different classes according to travelers’ attitudes towards travel time reliability.A travel time reliability based traffic assignment model with multiple user classes was formulated through a variational inequality(VI) approach.A diagonalization algorithm was presented for the model.As an example,the calculation results on a small network demonstrate that the model can reflect travelers’ route choice behaviors in uncertain environments.

Cooperation Intensity of Enterprises in Supply Chain

LIU Weihua, JI Jianhua

2007, 20(1): 120-124.

[Abstract](1356)

Abstract:
A new concept,cooperation intensity between enterprises in a supply chain,was proposed.Its two main influencing factors are enterprise competence and cooperation resistance coefficient.The method to calculate the cooperation resistance coefficient was proposed on the assumption that the cooperation intensity is proportional to the competences of the enterprises involved and reversely proportional to the cooperation resistance coefficient.The models to calculate the whole cooperation intensity and that between enterprises of adjacent nodes in a supply chain were presented.The total revenue and total cost were taken as the input parameters,and the methods to calculate the them were proposed for every stage of the cooperation process.

Positive Region Deduction of Decision Table and Computation of Core

QIN Keyun, GAO Yan

2007, 20(1): 125-128.

[Abstract](1334)

Abstract:
The problems of positive region reduction of decision table and computation of core were investigated so as to reduce the complexity of computation.The discernibility condition about decision objects was constructed,and the relationship between the positive region reduction and the set of discernibility attributes was discussed.A complete reduction method was proposed based on discernibility matrix and discernibility function.With this method,the positive region needs not to be calculated and the discernibility matrix can be constructed directly from the decision table.

Determination of Multielement in Industrial Wastewater Using Artifical Neural Network and Spectrophotometry

GUAN Di, XIE Qinglan, WANG Jiming, ZHANG Yanyan

2007, 20(1): 129-132.

[Abstract](1457)

Abstract:
In order to quickly test two groups of elements with overlapping absorption spectrum,Cd and Co,and Cr and Fe,in industrial wastewater,a novel method was proposed.With this method,the contents of the two elements in each of the two grounds can be tested synchronously and they need not to be separated.In the method,the color system of 4-(2-pyridyl azo)-resorcin(PAR)-Cd-Co and diphenylcarbazide-Cr-Fe is adopted,the spectrophotometry is utilized to test absorbency,and a drained artificial neural network is used to deal with data.The tested results of synthetical samples show that the recovery ratio of Cd,Co,Cr and Fe is respectively 101%,98%,102% and 98%,and the mean relative error is 1.61%,-0.23%,0.00% and-0.08% respectively.

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2007 Vol. 20, No. 1