2005 Vol. 5, No. 2

Display Method:
Stability of high-speed train
CENG Jing, WU Ping-bo
Abstract: In order to study the straight and circular curved track stability of each vehicle in the train set, a mathematical model of vehicle system with 17 freedom degrees was set up. The lateral component of coupler force was considered. The coupler force of vehicle(motor car or trailer car), which is the function of train speed and vehicle position in the train set, was determined by the resistant force of train operation. Three types of train compositions, 2M9T, 3M8T and 6M5T were taken into account. The Newton-Raphson iteration method was utilized to determine the equilibrium position of vehicle system, the QR method was adopted to calculate the eigenvalues of the system Jacobian matrix and the critical speed of the system where the equilibrium position became unstable was searched by the two divided method. The calculation results show that coupler force has little effect on the critical speed of each vehicle in the train set on straight track, but has certain effect for vehicle on curved track, the critical speed on curved track is lower than on straight track, the smaller the curve radius is, the lower the critical speed is, so the influence of coupler force on the critical speed of vehicle must be considered, when train runs on curved track.More>
2005, 5(2): 1-4.
Dynamic response of high-speed passenger car based on flexible car body model
WU Ping-bo, XUE Shi-hai, YANG Chen-hui
Abstract: In order to analyze the influence of passenger car flexible vibration on passenger car stability, two nonlinear dynamic models of high-speed passenger car were set up based on the rigid multi-body system and flexible multi-body system respectively, the influence of car body elastic vibration on its ride comfort was analyzed. The roller rig dynamic test for passenger car was implemented, the numerical simulation results for passenger car dynamic response were validated. The simulation and test results show that the stability index difference of the models in car body center is obvious, the higher the speed is, the larger the difference is, the flexible car body model will increase the ride index of car body. For the high-speed passenger car body made of aluminum alloy, the first vertical frequency of car body must be improve.More>
2005, 5(2): 5-8.
Spring plank stiffness influence of swing bogie freight car on its dynamics performances
YANG Guang-wu, XIAO Shou-ne, JIN Ding-chang
Abstract: In order to analyze the effect of spring plank stiffness on the dynamics performances of swing bogie freight car, the spring plank was considered as an elastic beam using finite element method. According to Hook law, the displacement stiffness and rotation stiffness were gotten when spring plank was connected with swing bolsters, different connection stiffness values were obtained by changing spring plank radius. The multi-body system dynamics model of global vehicle was established by multi-body system dynamics theory, based on taking into account each component connection and contact relation of vehicle. Rational radius of spring plank was presented by comparing with the main dynamics performances of vehicle under different spring plank radii. Analysis results indicate that along with the increase of spring plank radius, the critical velocity of vehicle decreases, the lateral riding index of car body increases, and the running stability indices fluctuate, each main dynamics performance of vehicle is better when spring plank radius is 10 m.More>
2005, 5(2): 9-11.
Theoretical model and numerical method of rail corrugation
JIN Xue-song, WEN Ze-feng, WANG Kai-yun
Abstract: The theoretical models of rail corrugation were analyzed, a theoretical model and its numerical method for rail corrugation attributed to material wear were put forward. In the model, the non-Hertzian rolling contact theory of wheel and rail system, rail material wear model and coupling dynamics of rail vehicle and track in the vertical and lateral directions were combined, a passenger car and the structure under rails were replaced by the systems consisting of dampers, springs and equivalent mass bodies, and the Euler beam was utilized to model the rails accounting for bending and twisting deformations, Kalker's non-Hertzian rolling contact theory of three-dimensional elastic bodies was modified to calculate the creep forces and frictional work density on the contact patch of wheel and rail. It was assumed that the material loss unit area of the contact patch was proportional to the frictional work density that determines the wear depth of the rail running surface. The presented model and its numerical method were used to analyze two kinds of corrugation cases. The results show that the initiation and development of the corrugations caused by various track defects, such as track gap, scratch, dent, sleeper pitch and random geometry irregularities can be analysed, the evolution of initial corrugation on rail running surface caused by manufacturing and grinding can be simulated, they are feasible to protect the initiation and development of rail corrugation.More>
2005, 5(2): 12-18.
Uneven surface effect on temperature distribution of wheel and rail contact
ZHAO Xin, WEN Ze-feng, JIN Xue-song
Abstract: In order to study the relation of the damaged surface and temperature resulted from wheel and rail friction, a heat coupling model of rolling and sliding of wheel and rail was put forward to calculate the temperature rise with a combination method of finite element method and finite difference method. In the model, the non-steady heat conduction between the contacting surfaces of wheel and rail, heat convection and heat radiation between wheel and rail and their ambient were tested. The effect of the surface unevenness of wheel and rail on the frictional temperature was analyzed in the rolling and pure sliding states of wheel on rail. The numerical results show that the surface uneveness of wheel and rail can lead to spalling in short sliding, its effect on the temperature rise be ignored in long sliding and rolling.More>
2005, 5(2): 19-22.
Effect of extracting and reclaiming process on aging degree of asphalt
TIAN Xiao-ge, MO Yi-kui, ZHENG Jian-long
Abstract: Different aged asphalts were dissolved in trichloroethylene, then were reclaimed with vacuum rotating reclaimer. Systematic test was made, the penetration, softening point, ductility, viscosity, dynamic shear modulus, phase angle, bending creep stiffness and tensile strength of the various aged asphalts and the corresponding reclaimed asphalts at low temperature were analyzed. [HJ] The influence of the extracting and reclaiming process on the aging degree of asphalt was concluded through analyzing the variances of various performance indices of different aged asphalts before and after the extracting and reclaiming process. The test results show that the variances of various performance indices are small for various aged asphalts after the extracting and reclaiming process. Considering the test error, it is concluded that the extracting and reclaiming process has little impact on the aging degree of asphalt binder by using revolution vacuum reclaimer, so the aging degree of asphalt binder can be evaluated using the asphalt reclaimed with revolution vacuum reclaimer.More>
2005, 5(2): 23-26.
Durability of porous asphalt mixture
XU Hao, NI Fu-jian, CHEN Rong-sheng, LIU Qing-quan
Abstract: This paper investigated the influence of asphalt binder properties and aggregate gradings on the durability of porous asphalt mixture utilizing performance-based test. Two types of aggregate gradings and four kinds of porous asphalt mixtures with the same air voids but different asphalt contents were tested. The study results show that increasing the viscosity of asphalt binder at 60℃ and selecting appropriate aggregate grading can promote the dynamic stability, hydraulic stability and low-temperature stability of porous asphalt mixture, make sure good durability of porous asphalt mixture.More>
2005, 5(2): 27-31.
Noise reduction performance of exposed-aggregate cement concrete pavement
HAN Sen, DONG Yu-ming, CHEN Hai-feng, ZHANG Dong-sheng, LU Xue-min, SHI Yan-qiang
Abstract: In the indoor pavement noise test, the paper used tyre-dropping method, adjusted different particle diameters and different gradations to obtain the cement concrete slabs of different texture depthes and surface characteristics, analyzed the correlation between the pavement texture and the pavement noise on the cement concrete slabs of different surface characteristics. Analysis results indicate that there is quadratic regression correlation between the pavement texture depth and the pavement noise, the texture of exposed-aggregate cement concrete pavement (EACCP) makes the sound level of above 1.25 kHz frequency be reduced apparently, and it has the tendency that the higher the noise frequency is, the larger its decrease degree is, when its frequency is 1.6 kHz, the pavement noise level of smooth cement concrete slabs is 87 dB (A), but the pavement noise of exposed-aggregate cement concrete slabs is (80 dB (A), ) it is reduced by (7 dB (A).) So proper EACCP can reduce pavement noise greatly, is a prosperous pavement in environmental protection.More>
2005, 5(2): 32-34.
Subgrade deformation forecast of frozen soil based on phase space reconstruction
HOU Shu-guang, WANG Shuang-jie, HUANG Xiao-ming
Abstract: The rules of permafrost subgrade deformation were analyzed by maximal Lyapunov exponent method, the phase space reconstruction of subgrade deformation was discussed. It is pointed that various delay time and embedment dimension are two important influence factors on the exponent, when delay time equals 1, embedment dimension equals 5, steady maximal Lyapunov exponent is 0.005 28. Using the exponent value, the maximal relative error of deformation forecast value and measure value is 0.749%, the minimal relative error is 0.135%. The results indicate that maximal Lyapunov exponent ideally reflect the chaos characteristic of subgrade deformation, forecasting subgrade deformation by maximal Lyapunov exponent is feasible.More>
2005, 5(2): 35-37.
Influence factors on surface crack of semi-rigid base course
WANG Hong-chang, HUANG Xiao-ming, FU Zhi
Abstract: Focusing on the severity of semi-rigid base course shrinkage crack, a finite element analysis model of 8-node isoparametric elements was established, the mechanics analysis of the influence factors on surface crack was made by FEM (finite element method) software ABAQUS. Analysing results indicate that the greater the temperature shrinkage coefficient of material is, the stronger its sensitivity to temperature dropping is; the greater the dry shrinkage coefficient of material is, the stronger its sensitivity to the ratio of water loss is; the stress intensity factor (SIF) at the surface crack tip of base course has linear increase relation with the temperature shrinkage coefficient, dry shrinkage coefficient and base course modulus. So in the design and construction of semi-rigid base course, the temperature shrinkage coefficient and dry shrinkage coefficient must be reduced, and base course must be avoided rolling in 7 d of base spreading.More>
2005, 5(2): 38-41.
Geocell application in reinforcing soft subgrade of railway
YANG Xiao-hua, DAI Tie-ding, XU Xin-zhuang
Abstract: In order to reinforce the soft subgrade of railway effectually, guarantee train safety, the engineering mechanism of railway subgrade reinforced by geocell was analyzed by using Marc program, a full-scale load-bearing test of soft subgrade reinforced by 4 types of geocells was carried out, by using flat load-test method. The different types of geocells are 34 cm×10 cm, (40 cm)×10 cm, 34 cm×15 cm and 40 cm×15 cm. The subgrade disease in the site of K241+(450~)550 of Yang'an railway was treated by using geocell. The result shows that geocell can restrict the lateral replacement and diffuse stress of railway subgrade effectively, its maximum lateral replacement is decreased by 17%, its maximum vertical stress is decreased by 9.3%, its stress is well-distributed by using geocell, its bearing capacity can reach more than 180 kPa, the cost of reinforced subgrade by using geocell is decreased by 9.3%. On-the-spot observation in 6 a shows that its maximum settlement is 28 mm, its minimum settlement is 13 mm. This engineering practice proved that the method of using geocell to reinforcing railway subgrade is effective.More>
2005, 5(2): 42-46.
Earth pressure computation method of reinforced earth retaining wall
LEI Sheng-you, HUI Hui-qing
Abstract: In order to reasonably compute the earth pressure, the order of filling and compacting earth behind reinforced earth retaining wall was analyzed, the compacting factors and deformations of backfills behind the wall were studied, the static equilibrium equation of differential earth unit in definite width was set up, and a formula of earth pressure acting on the surface of the wall was gained. When inverted filter is made of sandy gravel, the earth pressure gets bigger gradually along the wall from top to bottom, and finally tends to stable value, it is smaller than Rankine earth pressure. When inverted filter is made of sandy gravel mixed with clayey soil, the thinner inverted filter is, the smaller earth pressure is, when it reaches to a certain thickness, the earth pressure becomes negative, which indicates that some of wall faces be not forced, they possess structural function. The results show that the varying trend of earth pressure accords with the real measure result, the mothed is feasible.More>
2005, 5(2): 47-50.
Influence of horizontal curvature of prestressing tendon in transverse beams on concrete cable-stayed bridge inclined web
WANG Yi, YE Jian-shu, GU Xiang-feng
Abstract: Aimed at the cracks in the concrete inclined web of concrete cable-stayed bridge because of the horizontal curvature of prestressing tendon in transverse beam, the tensile stress was analyzed with elastic theory. This paper assumed the curve of strand as line, used distributed load to replace the action of prestressing tendon on concrete inclined web, based on the elastic mechanics formula of infinite plate with concentrated force acting, derived the simplified formula for calculating the stress of concrete inclined web through integral on line and coordinate switch. The results show that the error of considering the curve of strand as line is less than 2%, through the comparison with the result of FEA(finite element analysis) and experimental data, the error of principal tensile stress is less than 0.2 MPa, which prove that the precision of the method meets engineering calculation requirement, the method is feasible.More>
2005, 5(2): 51-55.
Closed-loop control of turbine engine system in super deep operation condition
LUO Kai, DANG Jian-jun, WANG Yu-cai
Abstract: Open-loop thermal cycle turbine engine system is very fit for modern high speed autonomous under water vehicle(AUV) because of its good operation performance and simple system structure, but this power system can't keep its stability when it works in the condition of ultrahigh drain pressure and low speed, such a behavior makes the design of control system difficult. In this paper, the closed-loop control model of turbine engine system working in super deep operation condition was built, utilizing the slight inertia characteristics of executing machine and combustion chamber pressure, the control law of adjusting propellant flow was devised instead of the usual control law of adjusting capacity of variable capacity fuel pump. The respondence of the system is no overshoot in changing speed process, its rising time is less than 8 s, the dominating control parameters are allowed to change over 30%. Simulation results show that this control algorithm is simple and robust, the control system be regulated easily, its control quality is good.More>
2005, 5(2): 56-60.
Diameter optimal design of slurry transportation pipeline
LI Xiao, HE Yan-ping, TAN Jia-hua
Abstract: In terms of nonlinear optimization method, this paper presented a mathematical model with respect to the diameter optimal design for slurry transportation pipeline. In the condition that pumps configuration, slurry concentration and pipeline material were known, the minimum of unit price per cubic meter of transporting earth was taken as objective function. In the model, unit price was equal to the ratio of annual expenditure to annual transport quantity. For the annual expenditure, the annual cost of pipeline material and the annual operation cost of pumps were considered, which had a close relation to the pipe diameter. Based on detailed analysis of the physical property of slurry and the characteristic curve of transport equipment, the suspension property of slurry and the operating point of whole transportation system were taken as mainly constraint conditions. The numerical-computational results show that the optimal diameter and the flow of the pipe and the final value of the pipe thickness equal 0.895 7 m, 3.134 m3/s and (2.6×) 10-3 m respectively, compared with the computational diameter 0.9 m of multi-scheme optimization method, the diameter is more accurate.More>
2005, 5(2): 61-64.
ASM exhaust emission characteristics of light vehicle
PENG Mei-chun, ZHAO Xin-ze, XU Zhi-gang, FAN Jing-ming, JIANG Bo-cheng, WANG Wen-tao
Abstract: In order to cleanse city air, reduce vehicle emission, the paper studied the exhaust emission characteristics of light gasoline vehicle by the emission test of acceleration simulation mode(ASM) for more than 3 000 used vehicles, analyzed the relationships of CO, HC, NOx emission levels with vehicle driving distance and vehicle age, derived their tropic formulas. The results indicate that CO, HC, NOx emission concentrations increase by 0.24~3.73 times with driving distance increase from 1.0×105 km to 3.0×105 km, CO, HC, NOx emission concentrations increase by 1.7~2.0 times with vehicle age increase from 2 a to 10 a. The nonconformity ratios of CO, HC, NOx emission are less than 10% when vehicle age is less than 4 a, but they are more than 20% when it is more than 10 a.More>
2005, 5(2): 65-67.
Current status and development tendency of automobile steer-by-wire system
HE Ren, LI Qiang
Abstract: With the development of automobile and electronic industries, more and more x-by-wire systems are used to replace traditional mechanical systems. The main structure of steer-by-wire(SBW) system was described. The SBW system was subdivided into three main subsystems, such as steering wheel subsystem, controller subsystem and front wheel motor subsystem. Its function and working principle were analyzed. Its major features and key technologies were introduced, including sensor technology, bus technology, dynamical power and tolerance control technology. Its good application prospect and development tendency were presented.More>
2005, 5(2): 68-72.
Analysing method of customer segmentation and customer value of air cargo
ZHU Jin-fu, LIU Feng, GAO Qiang
Abstract: In order to make air cargo company obtain and keep its valuable customers, the cargo customers were classified into eight types according to customer value and fathfulness, the relative marketing strategies were put forward in view of that cargo customers were mainly cargo (agents.) The influence of flight load ratio on customer value was introduced into the existing customer value formulation to make it suitable for air cargo customer segmentation. An example shows that air cargo customer values have a difference when flight load ratio is considered and is not introduced, the difference is about 1/3, so the model can calculate the customer value and classify customers more properly, the model is feasible.More>
2005, 5(2): 73-76.
Altitude capability calculation methods based on minimum flight cost
WEI Zhi-qiang
Abstract: Based on considing wind speed effect on cruise Mach number, the computational methods of cruise Mach number and altitude capability were proposed, the minimum flight cost was their objective function, and the effective extents of wind speed, mass, temperature on altitude capability were analysed. Analysis results show that the effective extent of mass on altitude capability is great, the effective extent of wind speed on thrust-limited altitude is great, the effective extent of certrobaric location on maneuvering capability limited altitude is great. The maximum error is less than 1% between the computational results by the methods and the computational results by INFLT software without wind, the methods are feasible.More>
2005, 5(2): 77-79.
Optimal conflict resolution method based on inner-point restriction
CHENG Li-yuan, HAN Song-chen, LIU Xing
Abstract: In the condition of free flight, in order to ensure the distance of two aircrafts could not less than a given safety distance, the Pontryagin minimum principle(PMP) of optimal control theory and inner-point restriction condition were introduced to study the conflict resolution problem of free flight aircrafts, in which control vectors were restricted. Two different schemes were designed, one only changed flying velocity magnitude, the other only changed flying velocity angle. Different schemes had different control vectors, different control vectors had different restricted ranges. The optimal control variable was gained according to the PMP, the start time, end time and switch time of conflict resolution were obtained by inner-point restriction condition. An example shows that the method is feasible, the wasting cost of one aircraft resolution is tenfold of the wasting cast of two aircrafts resolution in changing velocity method, the wasting cost of one aircraft resolution is one third of the wasting cast of two aircrafts resolution in changing angle method when the intersectant angle of two aircrafts is smaller.More>
2005, 5(2): 80-84.
Information organizing and transforming of value-added information system of port and shipping EDI
SHI Xin
Abstract: As the rough primary information of current port and shipping EDI(electronic data interchange) is out of order, it must be translated into metainformation and value-added information in order to be effectively used. The structure of its information flow was set up, the basic model and the realizing technologies of information organizing and transforming were determined. It is suggested that metainformation can be organized in the form of traditional database and value-added information in the form of theme tree, the transforming technologies can be classified into two classes, the first class technology is related to how to transform the primary information into metainformation, the second class technology is to optimize metainformation and transform it into value-added information. The model takes advantage of the development of value-added information system of port and shipping EDI information.More>
2005, 5(2): 85-88.
Timetable optimization for inter-city train of transit type
QIN Jin, SHI Feng
Abstract: In order to optimize the timetable and achieve the maximal social benefit, the problem of optimizing timetable was divided into three dependent sub-problems, such as the first train time, the headway and the number of its running per day. A optimization model was established based on the minimization of passengers' cost and railway enterprises' operation cost. A analytical solution was presented for the model. The number of train running per day is 30 when the cost is minimum, the timetable is obtained. The computing result accords with the optimal result of real analysis, so the method is feasible.More>
2005, 5(2): 89-93.
Dynamic OD estimation model of urban network
HE Zhao-cheng, YU Zhi
Abstract: In order to study on dynamic traffic demand, which is based on dynamic traffic management and control, the time-varying relation between OD flows and intersection turning counts was analyzed. By introducing intersection turning counts as additional system measurement, a state-space model considering both link counts and intersection turning counts was established, and a new dynamic OD estimation model of urban network was set up, an efficient method based on inequality constrained Kalman filter was proposed to estimate OD matrices dynamically. The proposed model and method were tested by a synthetic network, which was generated by microscopic traffic simulation tool Paramics. The simulation results show that applying the new model, the absolute and relative estimation average errors are reduced by 9% and 20% respectively, and it has better tracking ability to the time-variation of dynamic OD flow, the results are superior to the computational results of traditional model that only considers link counts.More>
2005, 5(2): 94-98.
Multi-view integrated-modeling methodology based on UML
ZHOU Yong-hua, LI Rui-min, LIU Chong, LU Hua-pu
Abstract: The design of intelligent transportation system requires systematic modeling and design approaches. This paper presented multi-view integrated-modeling methodology based on unified modeling language(UML), elucidated the procedure of multi-view integrated-modeling using the typical examples in the design of transportation management information platform. In the system design procedure, the descriptions of organization view, function view and process view were closely crossed and parallel, their information objects were described by information view, the physical entities of all other views were described by resource view. Practical application results demonstrate the necessity of multi-view integrated-modeling methodology, it can effectively support the modeling activities and document organization in the design process of intelligent transportation system.More>
2005, 5(2): 99-105.
Vehicle device system of intelligent guiding
WANG Jin-guo, WANG Wei-ya, TIAN Feng, WEI Jun-bo
Abstract: In order to improve the operation efficiency of public traffic system, the data flow of public traffic system was analyzed, a vehicle device of intelligent guiding system was designed, and the structure of the system based on SMS(short message service) was studied. The system could transmit the information of public traffic among buses, bus stations and management centers. Applied results show that the system equipment performance is steady, the system can realize vehicle management effectively, and connect with other intelligent systems easily.More>
2005, 5(2): 106-109.
Weight value determination method of highway construction comprehensive evaluation
MA Rong-guo, LIU Yan-ni
Abstract: In order to overcome the large computing and subjectivity of analytical hierarchy process(AHP), this paper put forward a new method of weight value determination in the comprehensive evaluation of highway construction. According to the advanced AHP, the weight values given by every expert of the indices could be received, they were determinated by entropy theory, then the synthetic weight values were received. Applying the method, the weight values of three indices were 0.394 6, 0.329 0 and 0.276 0 under the effect levels of natural environment, which were the influence degrees of water environment, atmosphere environment and sound environment. The computing results show the weight values of the factors can be computed, the subjectivity of AHP is overcome, the method is feasible.More>
2005, 5(2): 110-112.
Strategy choice of port logistics enterprises in price war
FENG Xue-jun, YAN Yi-xin
Abstract: Price war has become one of major threats to the development of regional port logistics enterprises, the selection of strategy to deal with or avoid the threat has been focused on by port logistics enterprises. Bertrand oligopoly model was applied to analyze the benefit of establishing port logistics enterprise alliance, a series of payoff matrices were formulated to study the strategy choice of port logistics enterprises in price war. It is pointed that the regional port logistics strategic alliance, guided by differentiation strategy for development in non-price competition, is an efficient way for enterprises to meet the challenge, achieve optimal competition, promote the sustainable development of port logistics industry and benefit the regional economy.More>
2005, 5(2): 113-116.
Logistics enterprise classifying model
MAO Hai-jun, ZHANG Yong, LI Xu-hong
Abstract: Aimed at the disorder of logistics markets and the essentiality of the classifying management for logistics enterprises, a characteristic indices system of logistics enterprise classifying was proposed by concluding and analyzing some logistics enterprise samples, and a classifying neural network model of logistics enterprises was founded based on Kohonen' SOM neural network. In the model, the logistics enterprises were divided into six groups, including transportation type, warehouse type, distribution type, agent type, express type and integration type, their characteristics were summarized. Using the model, five logistics enterprises are classified effectively, the classifying result is right, it accords with the real classifying object, the model is feasible.More>
2005, 5(2): 117-121.
Preference solution of fuzzy shortest path in logistics transportation networks
HAN Shi-lian, LI Xu-hong, LIU Xin-wang
Abstract: Considering the uncertainty of logistics networks, the paper proposed a fuzzy number ranking method of the shortest path based on weighting function centroid method, the arcs were represented by fuzzy numbers, the fuzzy shortest path could be obtained by the label method, which corresponded to preference information. The fuzzy number ranking method provided a parameterized representation method of decision preference information. With the given pessimistic levels expressed by maximum entropy weighting function, the fuzzy numbers ranking results, the fuzzy shortest path and the corresponding alternative project could be gained, which accorded with the preference information. A numerical example shows that the shortest path varies with preference parameter, and it is completely consistent with the given preference.More>
2005, 5(2): 122-126.