西南交通大学学报

Multiple Criteria Decision-Making Based on Similarity Degree Between Partial Orders

GUO Yao-huang, GUO Chun-xiang, GUO Qiang

2006, 19(1): 1-6.

[Abstract](1256)

Abstract:
A method of multiple criteria decision-making based on similarity degree between partial orders was proposed to solve the problem,in which decision makers provide only with ordinal information about the alternative shemes.The similarity degree is defined by utilizing fuzzy similarity relation.The two complete preorders of the alternatives are worked outt by calculating the dominated index and the dominating index of each alternative,respectively.The two complete preorders are then combined into a final partial order of the alternatives.Feasibility and effectiveness of the proposed approach were illustrated with a numerical example.

Complex Response of an Airfoil-Store System with Structural Non-Linearity

YANG Yi-ren, LIU Fei

2006, 19(1): 7-10,24.

[Abstract](1313)

Abstract:
The mathematic model of an airfoil-store system was simplified with the equivalent linearization method for aeroelasticity system.The parametric areas,in which there were complex flutter in the system,were obtained by introducing the subharmonic bifurcation condition of a symmetric piecewise linear oscillator.These areas were verified with numerical simulation.The results of the analyses show that,in addition to limit cycle response of cycle 1,there are complex responses,such as those in cycle 3,cycle 5,and cycle 7 etc.,in the system.

Control of Chaotic Motion of a Planar 2R Robot

LIU Zhao-hui, LI Li

2006, 19(1): 11-14.

[Abstract](1394)

Abstract:
The chaotic motion of a planar 2R robot was suppressed efficiently by applying periodic perturbation.The frequency and the amplitude of the applied periodic signal are two key parameters in the periodic perturbation control.The proper frequency and the amplitude of the periodic signal are obtained by calculating the largest Lyapunov exponent of the system to transform the chaotic motions into regular periodic ones.

Numerical Simulation of Temperature Field in Process of Casting Solidification

ZHAO Xin, WEN Ze-feng, JIN Xue-song

2006, 19(1): 15-19.

[Abstract](1661)

Abstract:
In order to obtain the variation law of temperature during casting solidification to improve casting quality,a finite element method combining with a finite difference method was used to discretize time and space variables in the governing equations of astable heat-conduction in the process of casting solidification so as to obtain the algebraic equations for casting and mold temperature.In order to solve the coupled problem of the equations governing temperature in the casting and the mold,alternative method of two-domain and an iterative method were used.In addition,varying time steps were automatically controlled in the light of the grade of change in temperature in order to save calculation time.For simplicity,some assumptions about boundary conditions were made,i.e.,the distributions of temperature in the casting and the mold are uniform at the beginning.The linear models exqressing the release of latent heat of the casting were used for the revised coefficient of specific heat.The calculational results show that with this method the distribution of temperature in castings can be simulated.

Diesel Oil Sorption Behaviours of Plant Charcoals

DAI Guang-ze, CHEN De-ke, NI Qing-qing, LUO Yu, LIU Ze-sheng

2006, 19(1): 20-24.

[Abstract](1250)

Abstract:
Diesel oil sorption behaviours were investigated experimentally on three kinds of plant charcoals including carbonized corn,cole and bamboo stalks.All the materials under investigation show some ability of diesel oil sorption,with the carbonized corn stalks being the best.Scanning electron microscope(SEM) analysis,mercury porosimetry and nitrogen adsorption were conducted to measure the sizes and distributions of pores and specific areas of the three plant charcoals.The results show that the plant charcoals with large pores(500 to 7 500 nm) have good diesel oil asorption ability because of good capillarity.There is no obvious relationship between diesel oil sorption behaviours and specific area,the effect of which is nelegible in terms of liquid adsorption.

Application of Support Vector Machine to Radar Emitter Signal Recognition

ZHANG Ge-xiang, RONG Hai-na, JIN Wei-dong

2006, 19(1): 25-30.

[Abstract](1474)

Abstract:
To enhance the ability of electronic warfare equipment to recognize signals,resemblance coefficient method was proposed to extract features from radar emitter signals,and support vector machine(SVM) was introduced to identify different signals automatically.Resemblance coefficient features have good stability and discriminability.SVM has good characteristics of simple structure,global optimum and strong generalization ability.Experimental results show that the introduced approach for recognizing radar emitter signals using resemblance coefficient and SVM is superior to the conventional ones.It works effectively in a large range of noise to signal ratio(5 to 20 dB) with the recognition error rate being as low as 2.68%.

Current Detection Control of Active Power Filter under Non-Ideal Voltage Source

CHEN Wei-rong, TANG Lei

2006, 19(1): 31-36.

[Abstract](1362)

Abstract:
In the ip-iq current detection method of active power filter(APF), the factors influencing detection precision were analyzed.These factors include the low pass filter(LPF) and phase locked loop(PLL).To eliminate the PLL error of non-ideal voltage source,an improved ip-iq current detection method was proposed.In the proposed method,the DC voltage regulation was processed seperately.The regulated value is added to the foundamental wave current obtained with LPF and reverse transformation.Simulation results show that the proposed method depresses the influences of non-ideal source voltage on the precission of ip-iq current detection method effectively and improves the performances of APF.

Slip of Induction Motor with Frequency Speed Control

CAO Yu-quan, YAN Li-mei, LI Meng-da, YAN Wei-zhong

2006, 19(1): 37-41.

[Abstract](1330)

Abstract:
Based on the torque-speed characteristic curve of induction motors,analyses were done on changes in slip with an variation in frequency when an induction motor drives different kinds of loads,including those with constant torque,constant-maximum torque,variable torque(except fans and pumps) and constant power,as well as fans and pumps.The formulas to calculate the slip and the speed under different frequencies and loads were presented.The analyses show that slip changes with an change in frequency for an induction motor with frequency speed control.This conclusion does not support the viewpoint that the slip of an induction motor with frequency speed control is constant.

Propagation Characteristics of Circular Coaxial Cables Filled with Multilayered Homogeneous Media and a Radial Conductor Plate

XIONG Tian-xin, YANG Ru-gui

2006, 19(1): 42-47.

[Abstract](1365)

Abstract:
By using the method of separation of variables,a recursive formula was derived for the electromagnetic fields in a circular coaxial cable with a radial conductor plate and filled with multilayered homogeneous isotropic media,and the relationship between the first and the Nth layers of the electromagnetic fields was determined.Then the eigenequations were obtained by using the recursive relations among their coefficients.The eigenequations were applied to a cable filled with one kind of medium,and a special eigenequation was derived.When the radius of the interior conductor equals zero,the circular coaxial cable becomes a circular waveguide,and its eigenequation was derived as well.Numerical results were presented to reveal the propagation characteristics of circular coaxial cables and the circular waveguide.

Background Extraction Method Based on Block Histogram Analysis for Video Images

PENG Qiang, LI Hua

2006, 19(1): 48-53.

[Abstract](1331)

Abstract:
A novel method of histogram analysis for background extraction of video images was proposed,which was derived from the pixel-based histogram analysis.The method make full use of the statistical properties of pixels between temporal frames and the correlation of local pixels in a single frame.When carrying out histogram analysis for background extraction,the proposed method is based on a 2×2 block of pixels,instead of a single pixel,so that the number of calculations are dramatically reduced.and can extract a sound background image from video sequence,simultaneously.Experiment was presented for comparison between the proposed method and the conventional pixel-based histogram analysis,and the results show that the proposed mehtod is faster and delivers better extracted backgrounds.

Key Technologies of L2 VPN Based on MPLS

XU Zhi-gen, SHEN Xiao-feng, DU Li-ping

2006, 19(1): 54-57,62.

[Abstract](961)

Abstract:
The disadvantages of traditional VPN (virtual private network) and the advantages of MPLS L2 VPN(layer 2 VPN based on multiple protocol label switch) were discussed.Data forwarding and the control are the two probelems to be solved to implement L2 VPN based on MPLS.The key technologies to implement MPLS L2 VPN consist of fowarding the L2 frames of VPN users,establishment of VC_FTN(forwarding equivalance class to NHLFE map) table based on VC(virtual circuit) information,and design of upper and lower state machines of VC between PEs using LSP(label switch path) tunnel.

Network Packet Generator Based on ActiveX Technique

ZHANG Nan, ZHANG Jian-hua, LI Zhi-shu, HE Wei-lin

2006, 19(1): 58-62.

[Abstract](1283)

Abstract:
To make convenient for programmers to generate network packets according to user’s requirement,a network packet generator was designed and implemented based on COM and ActiveX techniques.The LibnetNT DDL was used to program this generator and the low-level functions were encapsulated according to a unified interface.In this way,the generator can be used in different programming environments.Using this generator,a programmer needs not understand the details of low-level network protocols,and can generate desired network packets.It makes network programming more efficient and design elements more easily to be reused.

Trusted Computing-Based Security Model for Software Protection

ZHENG Yu, HE Da-ke, MEI Qi-xiang

2006, 19(1): 63-67,96.

[Abstract](1080)

Abstract:
With the help of the key technologies in trusted computing(TC) including integrity measurement,access control and seal storage,a TC-based secure model for software protection was proposed.A trusted platform module(TPM),which is an extention of current USB port,is employed in this model to prevent software from illegal copying,unauthorized modification and implementation of software.The technologies,such as dynamic password-based authentication,role-based access control,code transformation and channel encryption.Compared with traditional schemes,the proposed model implements mutual identification between user and software via TPM,and authentication mechanism via role-based access control(RBAC).

Heavy Metal Pollution of Dust,Topsoil and Roadside Tree Near by Main City Roadways

ZHANG Jian-qiang, SHIRAISHI Sayaka, WATANABE Izumi

2006, 19(1): 68-73.

[Abstract](1320)

Abstract:
To effectively control heavy metal pollution of city roadways induced by motors, the pollution index method was adopted to analyze and evaluate the characteristics of heavy metal pollution of roadway dust and topsoil near by roadside trees, and grasp the status of heavy metal pollution of city roadways.The capability for the leaves of a roadside tree to capture heavy metals and the diversity of the capabilities of different trees were discussed.The results show that the heavy metal concentration of roadway dust in downtown Tokyo increases with the traffic,and it is higher in dust than in topsoil.There is the trend,i.e.,Pb pollution,representing car pollution,declines in Tokyo,but its concentration is higher and Pb pollution will exist for a long time.Moreover,Pt pollution has been brought about due to the use of Pt in the exhaust-purified system of motor vehicles.The heavy metal concentration is always higher in the leaves of roadside trees than in those of homologous trees in a contrast spot,and there is a great difference in the heavy concentration of inhomogeneous trees and Rhododendron oomurasak can accumulate more heavy metal.As a result,to plant trees that can accumulate more heavy metals can restrain the diffusion of heavy metal pollution of city roadways.

Fast Weathering Law of Red-Bed Mudstone Slope

ZHANG Jun-yun, ZHOU De-pei

2006, 19(1): 74-79.

[Abstract](1219)

Abstract:
To provide a theoretical reference for the protection of red-bed mudstone slopes,a typical red-bed mudstone slope was monitored in the field.In addition,the laboratory experiment and finite element analysis of changes in temperature of mudstone specimens were conducted.The research result shows that the fast weathering of the red-bed mudstone slope occurs within 10 cm depth below the surface,and the variation of air temperature and the number of moderate rainfall have important effects on its fast weathering.The weathering rate increases with the heightening of air temperature and its difference,and the weathering deposits increase with the increment of the number of moderate rainfall.Furthermore,a big air temperature difference between the surface and inside of red-bed mudstone caused by rainfall is the key external factor affecting the fast weathering.

Effects of Stress-Free Temperature Difference on Force and Displacement of Welded Turnouts

WANG Dan, WANG Ping

2006, 19(1): 80-84.

[Abstract](1386)

Abstract:
In order to better guide the design,laying and maintenance of welded turnouts,the effects of stress-free temperature difference between two railway lines on the rail displacement and temperature force of a welded turnout were investigated.In addition,the influences of the link style of turnouts,the number of turnout,the style of turnout frog and the ballast resistance of road bed on the rail displacement and temperature force were analyzed.The results show that stress-free temperature difference between a welded turnout and an adjacent line or a turnout will lead a big longitudinal force and a great displacement of the welded turnout.

Fuzzy Edge Detection Based on Cloud Model

XUE Li-xia, WANG Zuo-cheng, LI Yong-shu, Wang Lin-lin

2006, 19(1): 85-90.

[Abstract](1376)

Abstract:
Based on the cloud model and the fuzzy set theory,a new edge detection method was proposed.Firstly,with this method,object clouds are generated using the region growth algorithm on the basis of the gray level of images.Secondly,boundary clouds and fuzzy membership regions for two or more clouds are obtained based on Boolean calculation.Thirdly,the optimal threshold is determined through maximizing the entropy of fuzzy partition based on conditional probabilities and entropy of fuzzy partition.Finally,an edge detection procedure is executed on the edge images.The experimental results show that with the proposed method plenty of lower level gray can be preserved to obtain more favorable edge detection.

Method of DEM Deformation Detection without Control Points Based on Differential Model

ZHANG Tong-gang, CEN Min-yi, WU Xing-hua

2006, 19(1): 91-96.

[Abstract](1420)

Abstract:
To improve the performance of the existing deformation detecting algorithms,a novel method based on the differential model was proposed for DEM(digital elevation model) deformation detecting without control points.In addition,it has been successfully used to the deformation detecting of Puwaigou,a debris region with a deformation proportion of over 50%.This method is based on the LZD(least Z-difference) algorithm,as a result,both the magnitude and the relationship of observations can be taken into account by introducing the differential model to greatly improve the ability of deformation detecting.The research result shows that its matching accuracy is higher than that of the M-LZD(LZD using M-estimator) and LMS-LZD(LZD using least-median-of-squares estimator) algorithms.

Application of IGS Ultra Rapid Products to Real-Time Tropospheric Monitoring

YIN Hai-tao, HUANG Ding-fa, XIONG Yong-liang, CHEN Xian-dong

2006, 19(1): 97-101.

[Abstract](1340)

Abstract:
Through comparing the accuracy and latency of broadcast ephemeris and three kinds of precise ephemeris provided by IGS(the International GPS Service),it was found that only IGS ultra rapid products(IGU) can meet the need for time of tropospheric monitoring.Based on the above recognition and by analyzing the precision of satellite orbits and clocks of IGU,a method integrating orbit relaxation with orbit quality index weighting was proposed and tested using data from four GPS reference stations in GPSNOS(GPS reference station network of Sichuan).The tested result shows that the proposed method can solve the uncertainty of IGU to effectively apply IGU to real-time tropospheric monitoring.

Two-Objective Programming Model of Ring Road around Urban Agglomeration

DU Jin-you, XIE Wen-li

2006, 19(1): 102-106.

[Abstract](1332)

Abstract:
A two-objective programming model was proposed to determine rational radii and service widths of urban ring roads.In the model,trip distance and general path impedance were taken as the two objectives.Three situations in terms of different OD pairs are considered in the trip distance function,and the model is solved with Dijkstra algorithm.The general path impedance function is expressed with a bi-level programming model of discrete traffic network with budget constraint,and the model is solved with branch and bound algorithm.The analysis results show that urban ring roads mainly serve the OD pairs with an angel less than 90 degree.The ring roads of Chengdu,the capital city of Sichuan Province,China,were taken as an example to show the feasibility of the proposed model.

Multi-level Recursive Forecasting Method for Road Accidents

LI Xiang-yong, TIAN Peng, ZHANG Nan, LONG Jun-ren

2006, 19(1): 107-110.

[Abstract](1524)

Abstract:
In view of the dynamic and time-varying characteristic of a traffic system,a multi-level recursive forecasting method was proposed,and a multi-level recursive forecasting model for forecasting road accidents was established.With this method,forecast of road accidents is divided into two parts: forecast of timevarying parameters and forecast of road accidents based on the former forecast.The forecasting precision is improved by precise forecasting time-varying parameters.The death toll of a province in China from 1989 to 1999 was taken as statistical data to derive the forcasting model.Simulation result shows that the average error of the forcasted death toll is 5.8% compared with the real statistical data of 2000 and 2001.

Economical Accounting Model of Ecology Environment

LIU Ying, LIU Dan, CHEN Wan-zhi

2006, 19(1): 111-115,121.

[Abstract](1115)

Abstract:
To more accurately estimate economical sustainability and actually show economical aggregate,environmental problems were explained from the point of view of economy.Based on the frame of the integrated environmental and economical accounting(IEEA) publicized by the United Nations in 1993,a framework of environmental and economical accounting was established through discussing and modifying of the concepts of production,assets and real environmental costs.As an example of environmental and economical analyses,the ecological environment of Chongqing City was investigated.The investigation shows that the ratio of ecological environment loss to GDP is about 20% in Chongqing from 1998 to 2000,i.e.,environmental cost is notable in Chongqing in the process of macro-economy running.

Models for Optimal Production Lot-Sizing in Hybrid Manufacturing/Remanufacturing System

DAI Ying, MA Zu-jun

2006, 19(1): 116-121.

[Abstract](1234)

Abstract:
To determine the optimal lot sizes for the manufacturing of new items and the remanufacturing of returned items in a hybrid manufacturing/remanufacturing system,two models were established on the basis of the assumption that the demand rate and the return rate are continuous and deterministic.The objective in these models is to minimize the total cost per time unit for ordering remanufacturing and manufacturing lots and holding returned and new/remanufactured items in stock.In addition,simple modifications of calculated lot sizes were proposed to make the number of lot sizes be a positive integer.The proposed models can be used to the conditions whether remanufacturing and manufacturing rates are finite or infinite.The validity of the models has been proved with an example.

Effects of Horizontal Merger on the Profits of Supply Chain and Its Members

LI Ling-feng, ZHANG Zhi-gang, HUANG Pei-qing

2006, 19(1): 122-126.

[Abstract](1314)

Abstract:
The influences of horizontal merger on upper suppliers and the profit of the whole supply chain were investigated,and the effects of the power structure within a supply chain during horizontal merger were analyzed.It was assumed that the merger was under Cournot competition.An example shows that the profit of a supply chain,as well as the members in the supply chain,depends on both the number of manufacturers taking part in the merger and the power structure of the supply chain.The larger the powers of suppliers are,the more profit they can obtain after merger.The status of manufacturers improves with an increase in the number of enterprises taking part in the merger,which counteracts the effect of increase in the power of supplies.

Low Regularity Well-Posedness for Nonlinear Wave Equations

YANG Han, WU Hai-gen

2006, 19(1): 127-130.

[Abstract](1246)

Abstract:
Low regularity well-posedness for the Cauchy problem of some nonlinear wave equations was studied.The Cauchy problem is well posed when the Sobolev exponents for the initial data is higher than a critical value.Otherwise,it is ill posed.The known results were extened from n=3 to n=1.The method in provement is based on energy estimate,scaling transform,and selection of initial values.

Decision Inference Based on Extended Decision Rules of Probabilistic Information System

PEI Zhen, DU Ya-jun, YING Liang-zhong

2006, 19(1): 131-134.

[Abstract](1306)

Abstract:
A probabilistic information system was used to express the uncertainty relationship between objects and attributes.Based on rough sets and average operator,extended decision rules of the probabilistic information system were obtained.Decision inference of the extended decision rules was implemented using fuzzy CRI(compositional rule of inference).

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2006 Vol. 19, No. 1