西南交通大学学报

MA Peisun, CAO Xi, ZHAO Qunfei

2006, 19(4): 407-414.

[Abstract](1627)

Abstract:
Gait designs were divided into two main categories: reference trajectory and natural dynamics.The former is based on walking data,central pattern generator or dynamic model.The latter is classified into passive dynamics and virtual model control.The advantages and disadvantages of the two main gait designs were analyzed.The future study is to increase walking efficiency for reference trajectory,and to add more functions for natural dynamics.The application of reinforcement learning in gait design and the problem of the curse of dimension were discussed.

Comparison of Performances of Two Magnetic Fluid Sealing Devices for Large Gap Magnetic Fluid Sealing

LI Guobin, SONG Shuncheng, CAO Xuejun, YANG Runtian

2006, 19(4): 415-418.

[Abstract](1595)

Abstract:
The magnetic flux concentrating performances of a magnetic fluid sealing device with opposite-pole teeth for a large sealing gap were numerically investigated with FEM(finite element method) and compared with those of a traditional magnetic fluid sealing device with single-side pole teeth.The results show that the magnetic fluid sealing device with opposite-pole teeth yields a much better sealing effect than that with single side-pole teeth.Compared with the latter,the difference in maximum magnetic flux density of the former is greatly increased at the middle pole tooth along the sealing gap direction,and the sealing pressure is approximately doubled.Especially,it is helpful to overcome centrifugal forces produced by high speed rotation on magnetic fluid for application in sealing of high speed shaft.

Governing Equations for Coupled Thermo-Hydro-Mechanical Behaviors in Unsaturated Rock Mass

HE Yulong, YANG Lizhong, YANG Jiyi

2006, 19(4): 419-423.

[Abstract](1456)

Abstract:
To study responses of unsaturated rock masses to coupled THM processes,the governing equations of coupled THM behaviors in unsaturated rock masses were derived by using the equivalent continuum model.The governing equations include those for thermal,hydrological and mechanical fields,and are based on the conservation equations for fluid and solid masses,linear momentum and energy,as well as the corresponding state equation and constitutive equations.In the derivation,thermal elasto-plastic constitutive relationship,rather than the assumption of local thermal equilibrium,was adopted,and the effect of temperature gradient on hydrological processes was taken into account.

Variation Laws and Computational Methods of Surface Subsidence Prediction Parameters

LI Yongshu, XIAO Linping

2006, 19(4): 424-428.

[Abstract](1385)

Abstract:
To reasonably determine prediction parameters in a surface subsidence model for an underground non-bedded shape room environment,the internal relations between prediction parameters and underground room shapes were analyzed based on the principles of surface subsidence.In addition,the variation laws of prediction parameters were investigated and the corresponding calculational formulas were derived.From the attitude of strata and the number of characteristic point at an underground non-bedded shape room,the method to determine the equation of stratum structure was presented.Finally,a practical example of surface subsidence predicting was given.The predicted result shows that compared with the conventional method,the proposed method raises the prediction precision of surface subsidence by about 40%.

Ocean Tide Loading Corrections in GPS Precise Positioning

CHEN Xiandong

2006, 19(4): 429-432,441.

[Abstract](1258)

Abstract:
Based on the theory of site displacement due to ocean tide loading,the site displacements of some IGS(International GPS Service) stations resulted from ocean tide loading were computed respectively using the data given by the Onsala Space Observatory of Sweden and the National Astronomical Observatory of Japan,and comparied in order to select a proper ocean tide model and ocean tide wave number to enhance the GPS(global positioning system) positioning.The comparison shows that to an oceanic or inland IGS station the difference between the two types of corrections is unremarkable,but to a coastal IGS station,the difference is remarkable.So it was believed that in GPS precise positioning,the corrections of site displacements resulted from ocean tide loading should be considered sufficiently,and the feasible selections of ocean tide models and ocean tide wave numbers are important so as to improve the accuracy of the corrections.

Energy Dissipation and Velocity Distribution of Internal Soliton Encountering Submerged Triangular Obstacle

CHEN Chenyuan, HSU Rongchung, CHEN Chengwu

2006, 19(4): 433-437.

[Abstract](1569)

Abstract:
Internal solitary wave(ISW) propagation is influenced by some physical factors.The most important factor of all is topography seabed in the ocean.Due to difficulties in field investigation,a wave flume was produced and tests were carried out to observe ISW propagation in the laboratory.The research shows that the classification of wave-ridge encounter can be divided into weak interaction,moderate interaction and strong interaction,and that a non-dimensional blockage parameter may be applied efficiently to determine the classification of wave-ridge encounter,being below 0.5 for the weak interaction,0.5 to 0.7 for the moderate interaction and over 0.7 for the strong interaction.Furthermore,the non-dimensional propagation speed of an ISW declines and the dissipation of wave energy increases as the blockage parameter increases.

Contents and Approach of Fire Scenario Design in Performance-Based Fire Protection

CHEN Junmin, ZHENG Xuesong, FU Yongsheng

2006, 19(4): 438-441.

[Abstract](1254)

Abstract:
To raise the rationality of fire scenario design,the contents and approach of fire scenario design were presented in detail from the needs of performance-based fire protection,and the advantages and disadvantages of the main models for heat release rate of fuel usually used at present were analyzed.The principles and processes of fire scenario design were discussed by taking the performance-based fire protection design of a mall in Chengdu as an example.It was pointed out that the design processes of fire scenario should include the setting of an ignition position,the determination of max heat release rate and the analysis of fire-spreading characteristics.

Investigation into Screening,Identifying and Solid-State Fermentation of Cellulolytic Strains

ZHANG Jianqiang, LI Yalan, LI Yong

2006, 19(4): 442-446.

[Abstract](1198)

Abstract:
Twelve strains were isolated from putrid straw,wood,soil and cattle feces etc. They can grow in a solid medium with(sodium carboxymethyl cellulose) CMC-Na as an only carbon source.One strain of fungi,preliminarily identified as Neurospora sp.,with a strong ability to decompose cellulose was screened from the 12 strains by a series of experiments.The experiment of single factor optimization about the solid-state fermentation of this strain was carried out.The research results shows that to the strain,the optimal carbon and nitrogen sources are that the mass ratio of straw to bran is(9 to 1,) and NH4NO3 0.5%;and that the optimal conditions for culture are that the inoculum’s size is 1 mL,the ratio of solid to liquid 1 to 3,culture temperature around 30 ℃ and cultivating time 96 h under the condition of a natural pH value.The carboxyl methyl cellulase activity and the filter paper activity of Neurospora sp.are 3551.1 and 386.7 μmol/(g·h) respectively under these optimal zymotic conditions.

Distribution Regularity and Homogenization of Track Rigidity for Ballastless Turnout

CHEN Xiaoping, WANG Ping

2006, 19(4): 447-451.

[Abstract](1692)

Abstract:
To identify the variation rule of track rigidity of a turnout laying on ballastless track,based on FEM(finite element method) a calculational model for track rigidity was established.In the model,the flexural rigidity of rails,the rigidity of fastenings,the rigidity of subgrade,slide plate,guard rail and spacer block are taken into account.The track rigidity of a Chinese No.12 speeding-up turnout,as an example,was calculated.The calculational results show that the rigidity of track is very uneven in the lognitudinal and transverse directions,the maximum ratio of total rigidity of inner rail and outer rail is 2.418,and the maximum longitudinal variety of total rigidity of inner rail reaches up to 242%.In addition,the disposal approach of rigidity of rail fastenings was discussed based on the model so as to eliminate the variety of track rigidity of a turnout and homogenize the rigidity of track.

Investigation into Computational Method of Self-Equilibrating Thermal Stresses in Concrete Bridges

PENG Yousong, QIANG Shizhong

2006, 19(4): 452-455.

[Abstract](1439)

Abstract:
An analysis was conducted to more accurately evaluate thermal stresses in structural members of concrete bridges.Based on theory of elasticity,a new method of evaluating self-equilibrating thermal stresses in concrete bridges was proposed.With this method,the transversal stresses are solved as a plane strain problem,and consequently the longitudinal stresses are calculated with an analytic formula.Finally,an example was given to verify the validity of the method.The example shows that calculated thermal stresses using the proposed method are almost the same as ones obtained by a 3D FEM(finite element method),while the conventional method based on structural mechanics can result an error over 30%.

New Device for Grounding Resistance Measurement of Grounding Grids along Qinghai-Tibet Railway

FU Longhai, WU Guangning, WANG Hao, LI Jin

2006, 19(4): 456-459.

[Abstract](1387)

Abstract:
To reduce the cost in grounding resistance measurement of grounding grids along Qinghai-Tibet railway,a new grounding grid resistance measurement device was designed.When the measurement is conducted with the device,the earth surface voltage distribution is measured first to determine the spot where voltage pole is installed.Frequency conversion technology was used to avoid alternating current disturbances and to get a reasonable measurement precision.Compared with the traditional method,in which a large current is necessary,the capacity,the wiring length and the needed labor of the proposed system are reduced by 80%,60% and 62%,respectively,with a difference in measured resistance being about 6%.

Support Vector Machine with Scaling Kernel and Its Application in Dynamic System Identification

HU Dan, XIAO Jian, CHE Chang

2006, 19(4): 460-465.

[Abstract](1522)

Abstract:
To improve the performances of dynamic system identification,a new method to formulate scaling kernel function for support vector machine was proposed.In the method,a compact support scaling function is derived first,and then based on wavelet multiresolution analysis a scaling kernel function with multiresolution characteristics is constructed from the compact support scaling function.It was proved that this scaling kernel function satisfies Mercer conditions and can be used as a kernel function for support vector machine.Simulation results show that the support vector machine with the proposed scaling kernel function has better modeling and approximation abilities than that with a Spline function kernel or RBF(radial basis function) kernel.

Improved FFT-Based MP Algorithm for Signal Sparse Decomposition

SHAO Jun, YIN Zhongke, WANG Jianying

2006, 19(4): 466-470.

[Abstract](1620)

Abstract:
An improved FFT(fast Fourier transformation) based MP(matching pursuit) algorithm was proposed to reduce the calculation load in signal sparse decomposition.In the algorithm,a radix-2 FFT is performed to calculate the crosscorrelation, because the calculation speed is the fastest when the length of the transform is of integral power of 2.Theoretical analysis shows that,for a digital signal with a length of 1 024,the speed of calculation of crosscorrelation using radix-2 FFT is 10.6 times as fast as that using direct calculation.Simulation results show that the calculation speed of the improved FFT based MP algorithm is 8.05 times as fast as that of direct calculation,and 3.64 times as fast as that of the FFT-based MP algorithm.

Resource Integration Scheme for Networked Manufacturing Platform

WANG Shuying, YUE Hongwei

2006, 19(4): 471-475.

[Abstract](1130)

Abstract:
A resource integration scheme for networked manufacturing platform was proposed using the techniques such as dynamic register,dynamic discovery and dynamic reference of Web service in an integrated environment.In the scheme,there are release wizards with unified interfaces and templates for Web service,and private UDDI(universal description discovery and integration) register centers to provide functions of dynamic register,discovery and reference.This scheme has been applied in the networked manufacturing system of Chengdu-Deyang-Mianyang cities,Sichuan Province,China.

Coverage Criteria for GUI Testing Based on Directed Graph for Window Navigation

YE Mao, GAO Haichang, FENG Boqin, ZHU Li

2006, 19(4): 476-480.

[Abstract](1419)

Abstract:
To evaluate the adequacy of a test suite for testing a program with graphical user interfaces(GUI),new coverage criteria based on directed graph for window navigation was proposed.The vertexes in the graph represent windows of GUI,and the directed edges represent user inputs on windows.The graph models the interaction between user and GUI.Top window coverage criterion,user input coverage criterion and length n user input sequence coverage criterion were proposed based on the graph.Algorithms were presented to compute the coverage rate on every coverage criterion.Experimental results show that the test suites satisfying the proposed criteria can reach a statement coverage rate as high as 90%,and a GUI fault detection rate as high as 79%.

Flexible Choice Strategy of Fuzzy Vehicle Routing in Urban Traffic under Uncertainty

ZHANG Yang, HUANG Qing, LI Jun

2006, 19(4): 481-485.

[Abstract](1502)

Abstract:
Based on the hypothesis of limited reason,a flexible strategy of dynamic vehicle routing problem with fuzzy travel time was presented through introducing the concept of decision-maker’s preference.A model was built for the flexible choice of vehicle routes with a certain departure time,and a heuristic algorithm was proposed.In addition,the influence of the decision-maker’s preference on the final objective of the flexible choice was discussed using the method of stochastic simulation.The result indicates that there is the optimal value of P* in a given transportation network under time constraint.

Routing Optimization for School Bus Problem

GUO Qiang, LI Lyo, GUO Yaohuang

2006, 19(4): 486-490.

[Abstract](1572)

Abstract:
A multi-objective nonlinear integer programming model was proposed to study the school bus problem.In the model,there are five objectives: to minimize the number of buses,to minimize total travel time of buses,to minimize total travel time spent by all children,to balance the loads among buses and to balance the travel time among buses,the objectives are sorted into four levels.A new heuristic optimization algorithm for solving the problem was presented.The algorithm starts with generating a minimum spanning tree to find basic routes,and then selects an adjustable unit to modify and determine the final routes.Further adjustment on the routes after the routes have been set is allowable if it follows some presented rules.

Selection of Routes for Avoiding Serious Accidents in Transportation of Hazardous Materials

WEI Hang, LI Jun, PU Yun

2006, 19(4): 491-495.

[Abstract](1281)

Abstract:
In order to avoid serious accidents in the transportation of hazardous materials,the condition against a serious accident was analyzed,i.e.,avoiding passing the route with a serious consequence as possible.A model for route selection was set up by taking population risk,average consequence and total consequence as the objectives to avoid serious transportation accidents,and by using the weighted method,the model can be solved by the shortest path algorithm.With this model,serious accidents in the transportation of hazardous materials can be avoided by controlling the average consequence and the total consequence.At last,a calculational example was given to show the validity of this model.

Comprehensive Evaluation Approach of Road Traffic Safety Based on Artificial Neural Network

LI Xiangyong, TIAN Peng, JIANG Gefu

2006, 19(4): 496-500.

[Abstract](1595)

Abstract:
To enhance the validity of evaluation,based on ANN(artificial neural network),a comprehensive evaluation model of the safety of road traffic based on BP(back propagation) neural network was built.By the learning of some effective samples given,the extraction and storage of experts’ knowledge and experiences were realized with this model.Two simulation examples show that the proposed comprehensive evaluation model of road traffic safety based on BP neural network is reasonable and feasible.

Overbooking Model for Revenue Management of Ocean Shipping Containers under Stochastic Capacity

LI Bingzhou, WU Zhenye, BU Xiangzhi

2006, 19(4): 501-506.

[Abstract](1325)

Abstract:
To solve the revenue management-based overbooking problem of ocean shipping container position under stochastic capacity,an overbooking model without considering empty container transportation under stochastic capacity was constructed by applying the probability theory and the optimization theory.In this model,expected total cost is taken as the optimization objective.In addition,it was investigated how to decide the optimal overbooking level of container position respectively for discrete and continuous probability distributions of transportation capacity.To solve the empty container transportation problem,an overbooking model considering empty container transportation under stochastic capacity was established,and it was proven that the optimal overbooking level declines under stochastic capacity if empty container transportation is considered.At last,a numerical example was given and the optimal overbooking level was calculated respectively with the two proposed models.The calculation shows that the optimal overbooking level with empty container transportation is 3 TEU(twenty-equivalent unit) less than that without empty container transportation.

Flight Conflict Detection and Regulation between Aircraft Based on Radar

WEI Guangxing

2006, 19(4): 507-511.

[Abstract](1738)

Abstract:
To avoid the air traffic collision,secure the flight safety and improve the air traffic controller’s capability to foresee and deal with flight conflicts,a radar-based coordinate system was established,and the concept of "horizontal detection" to foresee multi-traffic flight conflicts was brought forward.Furthermore,a method to foresee the horizontal detection of multi-traffic flight conflicts and the time slice of conflicts was proposed.The research shows that if the protected zone of aircraft Ai is intercrossed with the shadow of aircraft Aj on a horizontal surface and there is a vertical conflict,a flight conflict between aircraft Ai and Aj will occur.Under this condition,it is advisable to adjust the aircraft heading and speed or alter the flight altitude to avoid the flight conflict with the help of a surveillance radar.However,if there is no intercross in the time slice of horizontal and vertical conflicts,no flight conflict will happen between aircraft Aiand Aj.Finally,a simulation analysis was made to test the validity of this method.

Calculation Method of FANS Route Based on Ellipsoid Model

FANG Xuedong, HUANG Runqiu, WEI Guangxing

2006, 19(4): 512-516.

[Abstract](1254)

Abstract:
To improve the precision of area navigation,the formulas of calculating the initial course and route distance of an FANS(the future air navigation system) route was derived through spatial vector analyses.A simulation calculation was made by the Simpson numerical integral,and the simulated results of the initial course and route distance were compared with those based on the great circle route.The research shows that if the distance of a nearly east-west route is less than 1 000 km,the FANS route is approximately 0.35% longer than the great circle route,but if the distance of a nearly south-north route is less than 1 000 km,the FANS route is about 0.24% shorter than the great circle route.

Approach of Fuzzy Multi-objective Decision-Making Based on Lattice-Order Preference

HAO Guang, MOU Qifeng, ZHANG Dianye, GUO Yaohuang

2006, 19(4): 517-521.

[Abstract](1644)

Abstract:
By using the lattice theory,the totally ordering description of scheme optimization was extended to the lattice ordering one.Based on the decision-making theory and the fuzzy set theory,the concept of fuzzy multi-objective lattice-order decision-making was put forward.By introducing the concepts of fuzzy positive and negative ideal solutions,a model for fuzzy multi-objective lattice-order decision-making was constructed,and two algorithms,algorithms 1and 2,for this model were proposed.With the algorithm 1,fuzzy indexes are weighted,then fuzzy positive and negative ideal solutions are determined,and finally a satisfying solution can be obtained by comparing the difference between each scheme and the two ideal solutions.With the algorithm 2,fuzzy positive and negative ideal solutions are determined directly based on fuzzy indexes,then the difference between each scheme and the two ideal solutions is described by introducing the concept of satisfactory degree,finally a satisfying solution can be obtained through weighting.A numerical example shows the consistency of satisfying solutions obtained using the two algorithms.

Synthetic Evaluation Method Based Support Vector Classifier and Regression Machine

XIA Guoen, JIN Weidong, ZHANG Gexiang

2006, 19(4): 522-527.

[Abstract](1730)

Abstract:
To improve the synthetic evaluation and ranking abilities of machine learning methods,a support vector multi-classifier and a support vector regression machine were applied to the ranking of synthetic evaluation.By taking the evaluation of a management information system as an example,a contrast research between the proposed approach and ANN(artificial neural network) was made.Experimental results show that the difference of synthetic evaluation scores obtained by a support vector multi-classifier is more remarkable than that by ANN,and the relative error of synthetic evaluation scores based on a support vector regression machine is smaller than that based on ANN.

Model of Dynamic Price Cap for Regulation of Electricity Market

JIANG Dongrong, LI Qunzhan

2006, 19(4): 528-532.

[Abstract](1333)

Abstract:
To overcome the difficulty in designing price cap for regulation of electricity market,a novel model,dynamic price capping model,was proposed based on British RPI(retail price index),American ROR(rate of return) and PCM(profit capping model).The determination of profit factor and the incentive mechanism for new and existing power plants were discussed,and it is proved that the model can make the investment return fair.The new model not only provides a solution to suppressing the price spikes effectively,but also is an incentive for power plants to raise their efficiency and for the electricity market to attract investments.

Existence and Blowing-up of Solution of Wave Equation

YANG Ning, MOU Peihong

2006, 19(4): 533-536.

[Abstract](1129)

Abstract:
The global existence of solution to the initial-boundary value problem of a nonlinear fourth-order wave equation with a damping term and a force source term was proved based on the standard semigroup theory and by introducing a modified energy function.The effects of nonlinear damping and force source term on blowing-up of the solution were analyzed with an energy-compensation method.The solution blows up in finite time under initial energy that is negative enough.The upper bound of life span for the solution was obtained.

Traveling Wave Solutions to Kadomtsev-Petviashvili Equation

HU Yue, YANG Han

2006, 19(4): 537-540.

[Abstract](1377)

Abstract:
The generalized K-P(Kadomtsev-Petviashvili) equation with two parameters was studied.The existence of traveling wave solution of this equation was proved under some exponentially increasing assumptions for nonlinear term by using the mountain pass theorem without Palais-Smale conditions and corresponding Sobolev compact embedding theorem.

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2006 Vol. 19, No. 4