西南交通大学学报

Spacial Correlation between Heat Island and Green Space in Qingdao City Based on Remote Sensing

QIU Jian, JIA Liuqiang, WANG Yong

2008, 21(4): 427-433.

[Abstract](1736)

Abstract:
To provide a reference for the layout of urban green spaces to improve urban environment quality,the radiation transfer equation was employed to retrieve land surface temperature from Qingdao City’s Landsat ETM+ data,and heat island intensity(HII) was calculated from the land surface temperature retrieved.The mixed pixel model was utilized to work out the vegetation fraction(VF).Based on the above works,the correlation between HII and VF was discussed.The effects of the spatial distribution characteristics of green spaces and the circumstance around green spaces on HII were analyzed qualitatively using the resampling approach under a GIS environment.The results show that there exits remarkably negative spatial correlation between HII and VF,and under the same VF,samples with a compact green space or a farmland have a lower HII than those without.

Creep Behavior of Track Girders on Quasi-high-speed Dedicated Passenger Railway

XUE Weichen, WANG Wei, REN Tingzhu, HU Yuming

2008, 21(4): 434-440.

[Abstract](1812)

Abstract:
By taking track girders on Qinhuangdao-Shenyang quasi-high-speed dedicated passenger railway as prototypes,an experiment for about 3 a was conducted on three prestressed concrete model beams with a geometrical simulation ratio of 1 to 5 to probe into their creep behaviors.The research emphasizes the effects of types of concrete and tensioning methods of prestressed steel bar on creep deformation.Based on the age-adjusted effective modulus method(AEMM),a time-dependent finite element analysis program was developed,as a result,the time-dependent full-range analysis of the creep deformation of track girders can be made.A design suggestion was given to the creep deformation of track girders on a quasi-high-speed dedicated passenger railway by taking the types of concrete,the tensioning methods of prestressed steel bar and the difference between stresses in upper and lower fibers into account.The calculated results based on the suggestion agree well with the experimental data.

Seismic Time-History Response Analysis of Cable-Stayed Bridge with Local Cable Vibration

WANG Bo, ZHANG Hailong, XU Feng

2008, 21(4): 441-446.

[Abstract](1771)

Abstract:
To investigate the influence of local cable vibration on the seismic behavior of cable-stayed bridges,the analytical solutions of the first order natural frequency of inclined cables of a cable-stayed bridge were derived with considering the sag effect and the initial equilibrium state,and the FEM(finite element method) solutions of the natural frequency of inclined cables were obtained based on the multi-element cable model.The effect of local cable vibration on girder vibration was analyzed by inputting two kinds of seismic excitations with identical amplitudes but different spectrum properties.The research shows that the analytical solutions are identical with the FEM solutions,this means that the multi-element cable model can correctly reflect the vibration features of inclined cables.When low order vertical vibration mode frequencies of the girder are inconsistent with earthquake dominant frequencies,an additional damping effect on girder vibration will be caused;on the contrary,an amplificatory effect of vibration because of coupled vibration of cables and girder will be result in.

Qualitative and Quantitative Identification of Structural Damages Based on Stiffness Index and Frequencies

GUO Huiyong, LUO Le, LI Zhengliang

2008, 21(4): 447-452.

[Abstract](1628)

Abstract:
In order to identify structural damage locations and extents,a qualitative and quantitative identification method based on stiffness index and frequencies was proposed,and the effect of measurement noise on damage identification was investigated.Firstly,with this method,a stiffness index is used to localize damages,and the statistical theory is applied to analyze the effect of measurement noise of stiffness.Secondly,the frequency change method is used to identify damage extents quantitatively because of the high measurement accuracy of frequencies.In order to raise the identification precision of structural damages,an improved iteration strategy of the frequency change method was proposed.The simulation results show that the stiffness index is better than the flexibility index to structural damage identification and the improved iteration strategy is superior to the frequency change method in the identification precision.

Spatial Coupling Vibration Properties of High-Speed Vehicle-Turnout

CHEN Xiaoping, WANG Ping, CHEN Rong, GUO Likang

2008, 21(4): 453-458.

[Abstract](1589)

Abstract:
To provide a theoretic reference for the design of high-speed turnout,the contact force between wheel and rail and the vibration properties of a vehicle-turnout coupling system were analyzed by using the spatial coupling vibration theory for high-speed vehicle-turnout,and the structure irregularity of high-speed turnout was used as the vibration excitation.The research results show that the impact between wheel and rail is more exquisite at switch than at frog;the contact force between wheel and rail and the acceleration of a vehicle have 4 peak values;compared with switch rail and point rail,stock rail has a small acceleration,but the attenuation of its acceleration is fast;the vertical force transferred by spacer block is bigger than that transferred by rail fastening.

Reduced Elastic Modulus of Cracked Support Layer in Twin-Block Ballastless Track

ZHAO Pingrui, LIU Xueyi

2008, 21(4): 459-464.

[Abstract](1432)

Abstract:
With the finite element method,the bending stiffness of twin-block ballastless track with double combined slabs composed of a track slab and a support layer was investigated through changing the elastic modulus and thickness of the support layer and the interval between cracks,and the reduced elastic modulus of the cracked support layer was obtained.The research shows that small reduced elastic modulus of the cracked support layer will be result in under a great elastic modulus or large thickness of the support layer or a little interval between cracks.It is suggested that the reduced elastic modulus of the support layer should be determined based on the related parameters and possible crack intervals.

Effects of Modal Parameters on Ride Comfort Index under Harmonic Excitation

ZHANG Limin, CHEN Lin

2008, 21(4): 465-468,472.

[Abstract](1632)

Abstract:
An expression of the vertical ride comfort index of rail vehicles was derived by modal coordinate transform and described by modal parameters.The effects of modal parameters,i.e.modal frequency and mode,on the ride comfort index were studied by taking a secondary suspension system of a railway vehicle with 15-DOFs as an example.The research indicates that the comfort index is affected greatly by the modal frequencies of the vehicle body,different modal damping ratios have obvious different effects,and the effect of the first order modal damping ratio is greater than that of the second order modal damping ratio is.

Parameters of Secondary Lateral Stopping Block of Vehicle

LIU Jianxin, WANG Kaiyun, FENG Quanbao

2008, 21(4): 469-472.

[Abstract](1655)

Abstract:
In order to further the investigate influence of a secondary lateral stopping block on the dynamic performance of a vehicle and to supply a reference and guidance for bogie design,the effects of parameters of a stopping block,including stop gap and stop stiffness,on comfort and safety indices of running were probed into by taking the curve negotiation of vehicle as an example.The research results show that the stop gap and the stop stiffness have a great effect on the lateral acceleration of car body,but they have a little effect on the dynamic interaction indices of wheel/rail.Proper increase of the stop gap or reasonable decrease of the stop stiffness can reduce the lateral vibration of the car body to improve the running comfort.

Design of Hybrid Suspension System Based on DSP

WANG Li, ZHANG Jun

2008, 21(4): 473-477,503.

[Abstract](1473)

Abstract:
A digital controller for a hybrid electromagnetic suspension system with HTS(high temperature superconductor) coil and normal coil was designed.The hardware of the digital controller uses a fixed-point digital signal processor TMS320F2812.Design of software was presented.Experimental result shows that the hybrid electromagnetic suspension system keeps a large gap of 18 mm,low energy-consumption and stable suspension.

Misfiring Method for Identifying Angular Vibration Mode of ICE Crankshaft

HUA Chunrong, YAN Bing, DONG Dawei, XU Mingheng

2008, 21(4): 478-482.

[Abstract](1620)

Abstract:
A misfiring method for identifying angular vibration mode of ICE(internal combustion engine) crankshaft was proposed based on ICE dynamics and the basic equations about harmonic angular displacements of crankshafts.The relative amplitude of the angular vibration to an order of a cylinder mass is proportional to the amplitude of the phase difference between the angular displacements to the order on the measuring point caused respectively in the normal condition and in misfiring the cylinder.When the angular displacement amplitude to an order on the measuring point is approximately equal to zero in the normal condition of the ICE,the relative amplitude of the angular vibration to the order of a cylinder mass is proportional to the angular displacement amplitude to the order caused by misfiring the cylinder.Simulated and experimental results on 4-8 cylinder diesel engines show that the maximum error of the identified relative amplitude is 4.00%.

Analysis Method of Complex Fixed Axis Gear Trains Based on Graph Theory

LI Hua, YAO Jin

2008, 21(4): 483-487.

[Abstract](1370)

Abstract:
An expression and analysis method based on graph theory for complex fixed axis gear trains was proposed.In the method,a fixed axis gear train is described with a mesh matrix,a clutch matrix and a transmission matrix;movement interferences are identified by the rank of the transmission matrix;and the transmission routes are obtained with a depth-first search(DFS) strategy in the transmission matrix.The program flowchart for analysis of gear trains was presented.The proposed method was used to analyze a gearbox,and all feasible routes were found.

Algorithm Based on Bit Objects for Mining Maximal Frequent Patterns

YANG Junrui, ZHANG Tiejun, LIU Nanyan

2008, 21(4): 488-493.

[Abstract](1479)

Abstract:
A new algorithm based on bit objects,BFP-Miner,for mining maximal frequent patterns was proposed.It uses the bit objects to express data and to improve the FP-Tree(frequent pattern tree).The algorithm uses depth-first search strategy,and simplifies the support counting of frequent patterns with the characteristics of the bit objects and by compression of the database.Neither a conditional FP-Tree nor candidate patterns are generated during mining the maximal frequent patterns,so that the mining efficiency is increased.Experimental result verifies the efficiency of the BFP-Miner.

Multi-pattern Partial Quantum Search Algorithm

ZHOU Rigui

2008, 21(4): 494-497.

[Abstract](1415)

Abstract:
A multi-pattern partial quantum search algorithm was proposed to increase database searching speed.The algorithm groups the items of a database into equal blocks,neglects some unimportant information,and uses the multi-pattern quantum search algorithm to increase searching speed and concurrently search multi-patterns in the database.An example indicates that the proposed partial algorithm saves 1.325×106 iterations against the global search algorithm in a database with 7.206×1016 items.

Application of SVM Based on Differential Equations in APF

LIU Haichun, XIE Shaojun, WANG Guofeng, ZHANG Yun

2008, 21(4): 498-503.

[Abstract](1393)

Abstract:
Space vector modulation(SVM) was applied in current control of active power filters(APFs).Differential equations were used to transform current control of an APF to voltage control of the inverter to decrease the complexity in solving the system equations.The factors such as filter inductance and source voltage were taken into account to improve control precision.The results of simulation and experiment show that,with the proposed method,an APF has good dynamic characteristics when load or source voltage varies suddenly.

Freewheeling Current and Suppression in Inverter of Stand-Alone Photovoltaic Lighting System

CAO Taiqiang, XU Jianping, XU Shungang

2008, 21(4): 504-508.

[Abstract](1415)

Abstract:
Freewheeling current during dead-time of two switching transistors was analyzed.The switching transistors work in a series-parallel resonant inverter circuit of a stand alone photovoltaic lighting system with inductive or capacitive loads.A method to suppress the freewheeling current was proposed.The method uses high-order inductive harmonic current to compensate capacitive fundamental current.It also reduces the harmonic component in current and electromagnetic interferences,and improves the power factor.Experiments show that the freewheeling current suppressed with the proposed method is as low as about 67 mA.

Image Sparse Decomposition Based on Particle Swarm Optimization with Chaotic Mutation

LI Hengjian, YIN Zhongke, ZHANG Jiashu, WANG Jianying

2008, 21(4): 509-513.

[Abstract](1692)

Abstract:
A matching pursuit algorithm based on an improved particle swarm optimization(PSO) was proposed for sparse decomposition of images.The improved PSO uses the fine local search ability of the shrinking chaotic mutation to make the matching pursuit have good global search ability,improves the accuracy and increases the speed of atom matching in the redundant dictionary.The redundant dictionary employs the 2D Mexican hat function as the generating function to represent the edges and contours of images efficiently.Simulation results show that the proposed method is better than the general genetic and PSO algorithms both in speed and visual quality of the reconstructed images.

Inventory Model with Fuzzy Demand during Lead Time

DAI Ying

2008, 21(4): 514-518.

[Abstract](1427)

Abstract:
To deal with the inventory management problem with fuzzy demand during the lead time,the fuzzy set theory was applied to single-product inventory systems using(Q,r) policy.Uncertain demand during the lead time was characterized by a triangular fuzzy number,and an optimal order quantity model was established.The expected value method was adopted to obtain the expected value of the fuzzy demand during the lead time,and the center of gravity defuzzification method was applied to calculate the fuzzy expected value of the shortage.As a result,the minimized expected total annual cost was determined by a corresponding order point and quantity.Finally,a numerical example was given to illustrate the validity of the established model.

Dynamic Multidimensional Game Analysis of Returned Logistics Implemented by Household Appliances Manufacturers

HE Wensheng, MA Zujun

2008, 21(4): 519-523.

[Abstract](1485)

Abstract:
A dynamic game model for returned logistics implemented by household appliances manufacturers was set up on the basis of the multidimensional game theory to analyze the equilibrium profit of returned used household appliances implemented by household appliances manufacturers.The multidimensional game problems of two household appliances manufacturers,such as the brand profit of products,the investment of returned logistics and the market price of products,were investigated,and the equilibrium and the optimal managerial strategies based on the equilibrium profit were obtained.Finally,the two-dimensional game cases of this model were analyzed.The research idea may be applied to dynamic multidimensional game problems of various manufacturers in various fields.

Park and Ride Behavior in Stochastic Multimodal Network under ATIS

FAN Wenbo, JIANG Gefu

2008, 21(4): 524-530.

[Abstract](1662)

Abstract:
To investigate the effects of ATIS(advanced traveler information system) on P&R(park and ride) behavior,a multi-class network equilibrium formulation was proposed in a stochastic multi-modal network.The formulation is based on the following assumption that commuters can complete their journeys by three approaches,i.e.,auto mode,walk-metro mode and P&R mode,and make their travel decisions following a Probit-based stochastic manner whether they are equipped or unequipped with ATIS.A variational inequality model equivalent to the equilibrium conditions was established and solved using a simulation-based heuristic algorithm.Numerical results show that the quality of information has a significant influence on P&R behavior,P&R facility usage and ATIS market penetration.

Evolving Model for Scale-Free Network Based on Travel Choice

ZHAO Yue, DU Wen, CHEN Shuang

2008, 21(4): 531-534.

[Abstract](1291)

Abstract:
In order to further investigate the mechanism of scale-free networks,an evolving model for scale-free networks based on travel choice was established through analyzing the characteristics of urban resident trip networks,and the three special cases of this model were pointed out.The evolution process of urban resident trip networks was simulated numerically,and the expression of degree distribution exponent was obtained by using the mean-filed theory to show the same result as the simulation result.The research results indicate that urban resident trip networks have scale-free properties and are typical scale-free networks.

Model and PSO-Based Solution of Two-Dimensional Unbalanced Assignment Problem

LI Xueqin, PENG Qiyuan, FENG Wei, XIE Xiaosong

2008, 21(4): 535-539.

[Abstract](1660)

Abstract:
To solve the unequal transfer problem when the number of tasks differs from the number of vehicles,a model for two-dimensional unbalanced assignment problems was established,and the particle swarm optimization(PSO) was adopted to obtain its solution.Numerical simulation was conducted under different unequal assignments,and the simulation result was compared with the result based on the completed enumeration.The research result shows that PSO is superior to the completed enumeration in the probability of getting the optimal solution and the convergence speed,so the established model and PSO can be used for getting a satisfactory transfer plan.

Preparation of Carbon Nanotube with Small Diameters Using Co-Mo/MgO as Catalyst

JIANG Qi, ZOU Yongliang, ZHAO Yong

2008, 21(4): 540-543.

[Abstract](1658)

Abstract:
Carbon nanotubes(CNTs) with small diameters were prepared by catalytic chemical vapor deposition using Co-Mo/MgO as the catalyst and CH4 as the carbon source.The catalyst was prepared by citric acid complexation.The reaction atmosphere and temperature were studied deliberately to optimize the procedure.The morphologies of the obtained CNTs were characterized by transmission electron microscopy and high-resolution transmission electron microscopy.The CNTs with diameters about 10 nm were obtained with a yield over 110% when the reaction temperature was 950℃,the gas flow rates of H2,N2 and CH4 were 200,200 and 50 mL/min,respectively.

Plastic Deformation Mechanism of Nanocrystalline Nickel

JIA Chong, ZHANG Xiyan

2008, 21(4): 544-548.

[Abstract](1326)

Abstract:
Nanocrystalline nickel was cold-rolled with different strains to further research the mechanical properties of nano-metals,especially the mechanism of plastic deformation.The microstructure and deformation mechanism of nanocrystalline nickel were investigated by the transmission electron microscope(TEM) and the X-ray diffraction(XRD) analysis.In addition,the lattice constant of nanocrystalline nickel with different strains was calculated.The research results show that the grain size increases from 16.6 to 28.7 nm with the increase of deformation due to the growth of grains in some regions or directions.When the strain is less than 30%,the deformation is dominated by dislocation activity and grain rotation.When the strain exceeds 30%,partial dislocation generated by GBs(grain boundaries) leads to twinning,and the partial dislocation and the twinning harmonize during the deformation.The average lattice constant of nanocrystalline nickel is 0.353 3 nm greater than that of coarse grain nickel.

Selection and Fermentation of Mixed Cellulolytic Strains

ZHANG Jianqiang, WANG Yankun, LI Yong

2008, 21(4): 549-554.

[Abstract](1321)

Abstract:
A kind of mixed strains to be able to decompose straw cellulose efficiently was screened from soil and identified as Aspergillus sp.and Mucor sp.The solid-state fermentation of the mixed strains was optimized by orthogonal single factor experiments.The experimental results show that the optimal solid-state cultivation conditions are as follows: inoculating mycelium cultivated for 3 d,a straw-bran mass ratio of 8 to 1,(NH4)2SO4 with a content of 2.5% as supplement nitrogen resource,a solid-liquid mass ratio of 1 to 1.5,a natural pH value,cultivation temperature of around 28℃ and cultivation time of 5 d.When inoculation gross is 20% and inoculation ratio of Mucor sp.to Aspergillus sp.is 2 to 1,7 324.1 μmol/(g·h)as the highest carboxyl methyl cellulase(CMC) activity can be achieved,but when the inoculation gross and the inoculation ratio are 30% and 1 to 1 respectively,753.4 μmol/(g·h) as the highest filter paper activity(FPA) can be acquired.

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2008 Vol. 21, No. 4