交通运输工程学报

Relationship between characteristic of void and road performance of porous asphalt mixture

WU Hao, ZHANG Jiu-peng, WANG Bing-gang

Abstract: Three Marshall specimens of OGFC-13 with different gradations were selected, and their internal void distributions were obtained by using X-CT technique and digital graphic processing technique.The fractal characteristics of voids were computed by fractal theory, and the relationship between the void characteristics and the road performances for porous asphalt mixtures were analyzed.It is indicated that the split strength of porous asphalt mixture decreases with the increase of porosity, but increases with the increase of the fractal dimension of void profile.The permeation property increases with the increase of porosity, but decreases with the increase of the fractal dimension of void profile.The fractal dimension can explain the reason of the road performance difference for the mixtures with same porosity, so the fractal dimension may be adopted to analyze the void distribution and the changing law of road performance for porous asphalt mixture.More>

2010, 10(1): 1-5. doi: 10.19818/j.cnki.1671-1637.2010.01.001

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Vibration test method of semi-rigid base course material

LI Ming-jie, JIANG Ying-jun, ZHANG Jun-jie, WANG Shun, DAI Jing-liang

Abstract: Based on simulating the on-the-spot rolling working condition and impact of semi-rigid base course to maximal extent, the dry density and gradation of semi-rigid base course material were tested, the influence of vibration parameters on the compacting effect of semi-rigid base course material was studied, and a vibration test method of semi-rigid base course material was put forward. It is pointed that the optimum vibration parameters of vibration compaction test machine are vibration frequency at 30 Hz, excitation force at 7.6 kN, nominal vibration amplitude at 1.2 mm and vibrator mass at 300 kg, and the maximum dry density by 100 s vibration compaction is equal to the on-the-spot one. On the basis, the average accuracy of the maximum dry density and the average unconfined compressive strength by the method are 100.0% and 112.6%respectively, and they are 96. 9% and 42. 9% respectively by standard heavy compaction test and static compaction test. The result indicates that real base structure can be simulated accurately by the method, and the specimens produced by the method can represent the component structure and performance of on-site semi-rigid base.More>

2010, 10(1): 6-12. doi: 10.19818/j.cnki.1671-1637.2010.01.002

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Evaluation indices of freezing-thawing destruction for airfield runway concrete

DUN Xiao, CEN Guo-ping, HUANG Can-hua, ZHOU Qi, JIANG Jian-wen, YANG Xin

Abstract: In order to research the evaluation indices of freezing-thawing destruction for airfield runway concrete in north cold area of China, three concrete examples with anti-freezing capability were made, and their freezing-thawing devastating experiment was done by rapid freezing experimental machine. Their dynamic moduli of elasticity were measured by DT-10W, and the changing rules of relative dynamic moduli of elasticity, flexural strength losses, concrete mass losses and surface scale-offs under different freezing-thawing cycles were analyzed.The critical value of freezing-thawing destruction was presented for airfield runway concrete. Experimental result indicates that as freezing-thawing cycles accumulate, the compressive and flexural strengthes decline at different rates for the samples, of which the flexural strengthes lose more faster.The surface scaling areas and depthes of concretes become serious and mass losses have severe influence on the surface smoothnesses of the samples. According to the rules, the evaluation indices are put forward after 300 freezing-thawing cycles, which is that relative dynamic modulus of elasticity is less than 75% (flexural strength loss ratio is not more than 46%) and mass loss ratio is less than 1.0% (moderate surface scale-off).More>

2010, 10(1): 13-18. doi: 10.19818/j.cnki.1671-1637.2010.01.003

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Fuzzy-random reliability analysis of slope stability

LI Wei, KANG Hai-gui

Abstract: The fuzzy interval of limit state variable near its zero value was considered, ana a moael of fuzzy-random reliability analysis of slope stability was put forward. The influences of width fraction and migration fraction on the fuzzy reliability index of slope stability were studied in different situations including the variability of common soil parameters and the membership function distribution of fuzzy failure probability. Analysis result indicates that the slope of migration fraction and fuzzy reliability index curve decreases with the decrease of width fraction, which is irrelated to the variability and the distribution. For a certainty value of width fraction, the fuzzy reliability index decreases with the increase of migration fraction. The increase of the variability of soil parameters results in the decrease of the index. 3 tabs, 4 figs, 7 refs.More>

2010, 10(1): 19-23. doi: 10.19818/j.cnki.1671-1637.2010.01.004

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Calculation method of active earth pressure under limit state for geocell flexible retaining wall

QU Zhan-hui, XIE Yong-li, YUAN Fu-fa, YANG Xiao-hua, LIANG Wu-xing

Abstract: The horizontal displacement of geocell flexible retaining wall was analyzed by finite element method, its cut-off point in the middle of the wall was got, and the calculation method of active earth pressure under limit state was put up. The displacement mode above the cut-off point was near translational and the earth pressure of the part was calculated by Coulomb's active earth pressure theory. The displacement under the point was near rotary around the foot of the wall and the earth pressure of the part was calculated by level differential element method. The calculation results were compared with the measured results. Comparison result shows that the distribution shapes and growth trends of earth pressures from the calculation and measurement are basically same along the wall, and the calculated results are a bit smaller than the measured ones. The minimum deviation between the calculation values and measured values is 0.2 kPa, the maximum one is 2.9 kPa, and the average one is 1.2 kPa. Obviously, the calculation method is reliable.More>

2010, 10(1): 24-28. doi: 10.19818/j.cnki.1671-1637.2010.01.005

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Numerical simulation of one side rail irregularity

DING Jun-jun, LI Fu

Abstract: The power spectrum density of track irregularity was transformed to time-domain irregularity by inverse Fourier transform, and the correlation of various irregularities of America center line was analyzed. The relation between center line and left/right rail irregularities was used to transform the center line irregularity to the irregularities of left and right rails, and the rail/wheel interaction force response was computed by the simulation of vehicle system dynamics. The one side irregularities of America five grade railway and Chinese main line was compared.Analysis result indicates that all correlation coefficients among the center line irregularities are less than 0.3, they are low correlative and are considered independent of each other. All correlation coefficients of wheel/rail responses between the center line and left/right rail irregularities were more than 0.8, they are high correlative, so the equivalency transform is right.The one side power spectrum density of America five grade railway is higher than that of the Chinese main line in low frequency and is less in high frequency.More>

2010, 10(1): 29-35. doi: 10.19818/j.cnki.1671-1637.2010.01.006

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Flexural vibration suppression of car body for high-speed passenger car based on constrained damping layers

HUANG Cai-hong, CENG Jing

Abstract: In order to reduce car body elastic vibration, a mathematical model of the vertical vibration for high-speed railway passenger car based on rigid-flexible coupling system was established, in which car body was modelled as a simple uniform elastic Euler beam with free ends.Based on the amplitude-frequency characteristic analysis, the natural frequencies of vehicle system's components and the effect of loss factors on car body elastic vibration were researched. Constrained damping layers were partially pasted on the outside sheathing of car body, and the formulae of modal loss factors were derived through reasonable assumptions. Numerical calculation result illustrates that the first bending vibration mode of car body occurs near the frequency region where riding comfort is most affected. Consequently, it is important to suppress the vibration firstly. Good riding comfort can be achieved by increasing the loss factors of car body. Constrained damping layers treatment can increase car body structure's loss factors.In order to obtain the maximum loss factors, constrained damping layers should be struck on the place with largest car body flexural deformation, and there exists optimum length and thickness of every damping layer. Good damping effect of the vibration and good riding comfort of high-speed railway passenger car can be obtained by choosing appropriate characteristics of damping layers.More>

2010, 10(1): 36-42. doi: 10.19818/j.cnki.1671-1637.2010.01.007

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Coordinated control strategies of HEV powertrain with AMT

YUE Dong-peng, WANG Jie, ZHANG Jun-zhi

Abstract: For improving shifting quality of hybrid electric vehicle(HEV) with automated manual transmission(AMT), an integrated gear shifting control method was introduced.Five measures of improving vehicle's accelerating performance were provided to optimize shifting control strategies. A shifting simulation model was established on the platform of Matlab/Simulink, and the simulation of integrated gear shifting control was performed. The result shows that the model is capable of simulating the gear shifting process under various state-switches. The time of power break-up is only 1.2 s in the gear shifting process from gear Ⅰ to gear Ⅱ, so the method ensures power smooth transfer.The accelerating time of 0~100 km·h^-1 is improved from 14.82 s to 12.39 s, so the measures are effective.More>

2010, 10(1): 43-49. doi: 10.19818/j.cnki.1671-1637.2010.01.008

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Braking stability of tractor-semitrailer running on curve

SONG Nian-xiu, SU Jian, WANG Dong-jie, LIU Hong-fei, LIANG Cheng-jiang, LI Shi-wu

Abstract: In order to study the effect of braking condition on the stability of tractor-semitrailer running on curve, a whole vehicle model of tractor-semitrailer with 21 degrees of freedom was established by using dynamics theory and virtual prototype simulation software ADAMS. The change relations of folding angle, lateral acceleration, yaw angle velocity, vehicle speed, wheel speed and tire side-slip angle with time were analyzed when tractor-semitrailer ran on curve under the ultimate condition. Through the whole vehicle test of stable steering and step, the simulation accuracy of the model was verified. Simulation result shows that when tractor-semitrailer brakes after 3 s of turning, in 3 s, tractor's lateral acceleration becomes 0, yaw angle velocity reaches extreme value 33 rad·s^-1, then decreases rapidly.While trailer's lateral acceleration reaches extreme value 4 m·s^-2, and yaw angle velocity gradually decreases to 0. In the braking process on curve, tractor's rear axle first locks and slips, thus the folding phenomenon of tractor-semitrailer probably happens, which leads to the reduction of braking stability.More>

2010, 10(1): 50-55. doi: 10.19818/j.cnki.1671-1637.2010.01.009

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Mathematical models of refueling emission for car with ORVR system

WEI Hai-yan, HE Ren, CAI Jin-rong

Abstract: The structures of different kinds of ORVR(on-board refueling vapor recovery) systems were analyzed.Aiming at the systems with pressure control valve or not, tow mathematical models of mechanical and liquid seal ORVR systems were established by using mass transfer principle. The comparison between model simulation result and experiment data shows that the quantity of refueling emission for car with ORVR decreases by 97% compared with that of car with activated carbon canister.Because the inlet of filling pipe is entirely sealed, the refueling emission of car with mechanical ORVR system reduces by 37% compared with liquid seal ORVR system.When pressure control valve is installed in the ORVR system, the refueling emission of car reduces by 8%. Obviously, the ORVR technique can be used to effectively control the refueling emission of car and to reduce environmental pollution.More>

2010, 10(1): 56-59. doi: 10.19818/j.cnki.1671-1637.2010.01.010

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Robusth location model of enterprise logistics center

ZHOU Ai-lian, LI Xu-hong, MAO Hai-jun

Abstract: Based on the idea of robust design and stochastic chance constrained programming mehtod, a robust location model of enterprise distribution logistics centers was constructed under the uncertain conditions of customer's demand and manufacture center's processing amount, and the standard error of location allocating cost was integrated into object function to achieve robust location. The solving method of the model was discussed, and the programming thinking based on combination genetic algorithm was expounded. The model and its algorithm were validated by an example. Analysis result indicates that compared with normal model, the standard error of robust location model allocating cost reduces by 31.5%, and logistics network robustness enhances evidently, so the model is rational and valid.More>

2010, 10(1): 60-65. doi: 10.19818/j.cnki.1671-1637.2010.01.011

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Forecasting method of trip generation for higher education zone based on model selection and integration

ZHANG Wen-feng, ZHANG Xiao-hua, CENG Tao

Abstract: To improve the forecasting data reliability of trip generation for higher education zone, a forecasting method of trip generation was presented based on model selection and model integration. According to the model's evaluation indices, the trip generation models of zone were optimally selected by using ELECTRE method. The weights of optimal selected models were demarcated by using D-S evidence theory. Based on the weights, the trip generation of higher education zone was forecasted by using data fusion, and the forecasting result was contrasted with actual result. Analysis result indicates that the relative error of multi-model integration forecast is below 10%, and the forecast data is very close to actual situation, so the method is effective.More>

2010, 10(1): 66-71. doi: 10.19818/j.cnki.1671-1637.2010.01.012

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Modeling and simulation of collaborative management for airspace and traffic flow

SUN Xiao-yang, HU Ming-hua, ZHANG Hong-hai

Abstract: A theoretics of collaborative management for airspace and traffic flow was proposed, several management resorts were used such as ground holding, dynamic route and conditional route, and a methematical model was set up whose objective was based on the minimum cost of operation. The costs of opening conditional route and dynamic route were introduced in the model to reflect the relationship between traffic flow and capacity, and the model was tested by an example. Experimental result shows that the general flight cost decreases by 8 205 dollars, and its amplitude becomes flat after using collaborative management strategy for airspace and traffic flow, so the strategy can cut down delays, and reduce the expense of airline company. 1 tab, 4 figs, 10 refs.More>

2010, 10(1): 72-76. doi: 10.19818/j.cnki.1671-1637.2010.01.013

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Planning model and calculating method of period carrying capacity on busy existed railway main-lines

QU Si-yuan, XU Xing-fang

Abstract: According to the actual transportation mode and operating character of passenger trains and freight trains running together on busy existed railway main-lines, the existed calculating methods of carrying capacity were analyzed, and the study principle and the definitions of period and calculated division were set down. By analyzing the time of train interval and the overtaking between different class trains, the improved mode of negative index distribution was adopted, and the planning model and calculating method of period carrying capacity on busy existed railway main-lines were advanced.An example of certain division in up train graph on Huning line was given to explain the new method.Calculation result indicates that the academic numerical values of four period carrying capacities are 53, 26, 49 and 43 respectively, which accords with the actual situation of busy main-lines, so the model and method are feasible.More>

2010, 10(1): 77-81. doi: 10.19818/j.cnki.1671-1637.2010.01.014

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Whole life-cycle cost analysis of urban rail transit

CHEN Jin-jie, CHEN Feng, LIANG Qing-huai, GAO Gui-feng

Abstract: The whole life-cycle cost components of urban rail transit were studied, every indicator of subway cost and its proportion were analyzed quantitatively, subway earthwork cost and mechanical and electrical equipments cost were calculated in details. According to whole life-cycle cost analysis theory, the mathematical model of whole life-cycle cost for urban rail transit was built, its analytical steps were proposed, and subway ventilation and air conditioning system was put forward as an example. Analysis result shows that the earthwork cost is the largest among eight costs, accounting for 36.36%, with an average cost of 197 million yuan·km^-1; the second is mechanical and electrical equipments cost, accounting for 19.83%, with an average cost of 107 million yuan·km^-1. The cost of ventilation and air conditioning system is 41.804 million yuan, and the cost of platform screen door system is 32.378 million yuan, the cost of platform screen door system is lower, so the plan with higher capital cost may lead to the less operation cost, and the whole life-cycle cost of urban transport system may reduce.More>

2010, 10(1): 82-87. doi: 10.19818/j.cnki.1671-1637.2010.01.015

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Scheduling model and algorithm of integrating loading and unloading operations in same ship-bay at container terminal

CENG Qing-cheng, YANG Zhong-zhen, LU Jing

Abstract: To improve the operation efficiency of container terminal, a scheduling model of integrating loading and unloading operations was developed.By using the model quay cranes could perform loading and unloading operations simultaneously in same ship-bay. The objective of the model was to minimize the operation times of quay cranes and yard cranes by optimizing the stowage plan of outbound containers and the operation sequence of quay cranes. A bi-level genetic algorithm(GA) was designed to solve the model, in which the upper level GA aimed to find the optimal sequence for quay cranes, the lower level GA aimed to find the optimal stowage plan of outbound containers based on the operation sequence of quay cranes, calculate the total operation times of quay cranes and yard cranes, and return the results to upper level GA, so the scheduling plan was optimized by the feedback between upper level GA and lower level GA. Numerical tests were provided to illustrate the model and algorithm.Analysis result indicates that the operation times of quay cranes can reduce by 9.42%~1.53% by using the model, so the model and algorithm are efficient.More>

2010, 10(1): 88-93. doi: 10.19818/j.cnki.1671-1637.2010.01.016

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Simulation and experiment of crashworthiness for combined bridge guardrail

TAI Yong-gang

Abstract: To improve large bridge traffic safety quality, the basic structure of a combined bridge guardrail was identified by theoretical calculations and type investigation. A number of guardrail structure optimization designs were conducted by using computer simulation based on finite element theory, and the crashworthiness of optimized guardrail was validated by full-scale vehicle crash test.Analysis result shows that the guardrail structure can effectively protect errant vehicle, and its crashworthiness can reach more than 420 kJ, which agrees with SA degree of relevant standard in China. The experiment also validates the validity and reliability of data extracted from computer simulation.More>

2010, 10(1): 94-100. doi: 10.19818/j.cnki.1671-1637.2010.01.017

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Identification analysis model of traffic accident-prone locations based on geographical view angle

YUAN Quan, LI Yi-bing, LU Guang-quan

Abstract: In order to evaluate traffie accident-prone locations thoroughly and establish early- warning system, the geographical view characteristics of urban road traffic system was studied. The analysis model of traffic accident-prone locations was investigated through the application of relevant methods. The meaning and structure of evaluated road traffic system was confirmed. From different layers of traffic system including spot, line and plane, basic evaluation index system was established, and the analysis model of traffic accident-prone locations was constructed by integrating common statistics method, matrix analysis method and improved quality control method. The data selections of important parameters and the output forms of analysis results were discussed, and the accident-prone locations of nine roads in some city were analyzed. Analysis result indicates that road 4 is accident-prone road, road 3 has the most accident numbers and equivalent accident numbers, and road 5 has the most accident rate. After comprehensive evaluation, roads 3, 4, 5 are identified as accident-prone roads. So the model can identify and analyze the road traffic accident-prone locations comprehensively. 3 tabs, 6 figs, 10 refs.More>

2010, 10(1): 101-105. doi: 10.19818/j.cnki.1671-1637.2010.01.018

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Decision-making method of optimal reconstruction time for expressway

WANG Jian-qiang, YANG Yun-feng, XI Jiang-peng, XI En-chong

Abstract: In order to increase expressway capacity and improve expressway service level, a decision-making method of optimal reconstruction time for expressway was proposed. The statistics data of traffic from expressway toll stations were analyzed, and the traffic volumes of future years were predicted by using trend extrapolation method, multinomial regression method and growth factor method. According to the service level of expressway computed with the traffic volumes, the optimal reconstruction time was confirmed when the actual traffic volume equalled to the design traffic volume. Computational result shows that the service level of Xi'an-Baoji expressway is 1.0 in 2011, which is actual optimal reconstruction time, so the decision-making method is reliable.More>

2010, 10(1): 106-111. doi: 10.19818/j.cnki.1671-1637.2010.01.019

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Application of formal methods in train control system

CAO Yuan, TANG Tao, XU Tian-hua, MU Jian-cheng

Abstract: To ensure the correctness of train control system design and development, the ways of simulation, test and formalization were compared. According to the safe critical attribute of train control system, the characters related to system safety were propounded such as real time, hybrid, distribution(concurrence) and reactivity, and the specific formal methods associated with every character were introduced in details. The analysis and classification of the methods were done based on their mathematical basis and applications, and their advantages and disadvantages were given.Analysis result indicates that every method has determinate limitations, which is determined by the essences of model checking and theory proving. It is pointed out that the presentation of new method, the expansion of existing methods and the integration of many methods will be the development trend of formalization in train control system.More>

2010, 10(1): 112-126. doi: 10.19818/j.cnki.1671-1637.2010.01.020

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