2010 Vol. 10, No. 2

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Evaluated model and standard of segregation for asphalt mixture
TANG Xian, WANG She-liang, DAI Jing-liang
Abstract: The behavioral laws among particles were analyzed by using the fundamental theory of particle mechanics. A segregation model of asphalt mixture was established by using the angle of repose when it was piled. The calculation equation about the segregation index of potential energy was deduced. The index instrument was developed.The segregation index for asphalt mixture with maximum nominal particle size 16 mm was detected, and the standard of the segregation index was summarized by comparing test under different temperature conditions. Test result shows that the segregation index of potential energy is about 0.200, the compaction rate is about 0.40 near CA0.5, and they have least values.The mixture holds good workability and compacted-ability, which can decrease sharply the segregation during construction. The segregation grades of asphalt mixture are divided into no segregation, low segregation, middle segregation and high segregation in view of the standard. So the evaluated model and standard can be used to detect and differentiate the segregation of asphalt mixture at the spot.More>
2010, 10(2): 1-5. doi: 10.19818/j.cnki.1671-1637.2010.02.001
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Road performance of granite asphalt mixture
PENG Yu-hua, LIU Hui-xing
Abstract: The adhesion between granite aggregate and asphalt was evaluated by extending the boiling time and adding several kinds of anti-stripping agents. Taking the surface layer of granite asphalt mixture as the research objective, minor void volume was designed based on the target of water damage, and some tests including Marshall stability test, wheel rutting test, water stability test, accelerating aging test and Cantabro test were conducted under the conditions of adding MeadWestvaco, PA-1 and no adding anti-stripping agent. Test result shows that contrasted with no adding anti-stripping agent, granite asphalt mixture's stability, dynamic stability, residue stability and freeze-thaw splitting rate increase by 39.8%, 42.1%, 13% and 16% respectively, and its flying shards loss decrease by 4.4% in the condition of adding MeadWestvaco.While granite asphalt mixture's stability, dynamic stability, residue stability and freeze-thaw splitting rate increase by 14%, 22.9%, 8% and 12% respectively, and its flying shard loss decrease by 2.9% when adding PA-1. The technical indices of granite asphalt mixtures after accelerating aging test come up to the specifications when adding two kinds of anti-stripping agents.The study indicates that adding anti-stripping agent with good thermal stability is the key point to improve the road performance of the mixture, and the effect of MeadWestvaco is superior to that of PA-1. The way that mineral powder is replaced by 2% cement cannot fully meet the performance need of granite asphalt mixture.More>
2010, 10(2): 6-11. doi: 10.19818/j.cnki.1671-1637.2010.02.002
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Influence factors of bond performance between asphalt surface layer and semi-rigid base
WANG Shui-yin
Abstract: Referring to foreign LPDS shear test method, the influence of asphalt mixture, sticky layer material, semi-rigid base material, the interface of asphalt mixture and sticky layer material, the interface of viscous layer material and semi-rigid base on the shear strength between asphalt surface layer and semi-rigid base was studied with self-designed interior direct shear test and oblique shear test.The shear strength and the unit shear strength were the test evaluation indexes. It is shown that increasing the maximum nominal size and the compactness of asphalt mixture can improve interlayer bond strength. High strength, coarse and dense semi-rigid material can improve interlayer bond strength. Viscosity isn't main influence factor to select viscous layer materials, but the species and doses of viscous layer materials should be selected according to engineering practice test.Cleaning the surface of semi-rigid base is an important measure to improve bond interlayer's level.Prime coat should be sprinkled with 0.3~0.6 L·m-2 after the surface of semi-rigid base is cleaned. Casting single particle size, coarse specification and alkaline crushed stone above interlayer hot asphalt is easy to construct, and can improve interlayer bond strength.More>
2010, 10(2): 12-19. doi: 10.19818/j.cnki.1671-1637.2010.02.003
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Shear property demands of binding layer on concrete bridge pavement and simplified calculation
GU Xing-yu, WANG Wen-da
Abstract: The mechanical properties of several types of binding layers on concrete bridge pavements were analyzed by using finite element method, and the sensitivities between their shear strengths and several pavement parameters including thickness, modulus, lateral load and tire pressure were studied. The range of shear angle was obtained and a simplified calculation equation for the shear strength of bonding layer between pavement and concrete bridge was put forward. By varying shear angle from 25° to 65° during inner-door skew shearing experiment, the varying rules of shear strength of bonding layer with temperature were analyzed. Research result indicates that the thickness and lateral load are main influence factors for shear strength and shear angle, the shear property of bonding layer decreases rapidly with the increase of test temperature and shear angle, and the use of low modulus waterproofing roll with a certain thickness is disadvantageous to shear property. The sticking effect of bonding layer can be judged by the comparison of testing values and calculating values of shear strengths at different paving sites, which can be used to supervise the selection of water proofing binding layer.More>
2010, 10(2): 20-25. doi: 10.19818/j.cnki.1671-1637.2010.02.004
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Performance evaluation of Portland cement concrete pavement based on fuzzy complex matter element method
TIAN Xiao-ge, LIN Du, WU Sun-de
Abstract: The needs of maintenance and overlay for Portland cement concrete pavement (PCCP) were considered, the current Chinese technical specifications of cement concrete pavement maintenance were analyzed, and new evaluation index system and method were put forward. Pavement condition index (PCI), running quality index (RQI) and international friction index (IFI) were used to evaluate the functional performance of PCCP. The ratio of broken plate (DBL), the resilience modulus of base course, the load transferring capacity of the joint and the ratio of voided plate were used to evaluate the structural status of PCCP. A systematic pavement performance evaluation model was established by using fuzzy complex matter element method, and the fuzzy in classification of every index was considered. The weight of each index was determined by integrating analytic hierarchy process (AHP) method and entropy method to consider data objectivity and classification subjectivity. Computation result shows that the maximum correlation degree of evaluated pavement is 0.562 4 to the medium grade, and the second largest correlation degree is 0.319 4 to the poor grade, which means that the state of evaluated pavement is medium closely to poor grade according to the principle of maximum correlation, and is fit with the actual situation. The result indicates that the evaluation index system and method are feasible.More>
2010, 10(2): 26-29. doi: 10.19818/j.cnki.1671-1637.2010.02.005
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Methods of Hamburg wheel tracking tests for asphalt mixture
LI Pei-long, ZHANG Zheng-qi, LI Hong-hua, WANG Bing-gang
Abstract: Four kinds of asphalt mixtures were made and Hamburg wheel tracking tests were conducted with the specimens in the water and in the air at 50 ℃ and 60 ℃ individually, the influence of water and temperature on rutting depth was analyzed. The tests were carried on to analyze the influence of specimen thickness and molding ways on rutting depth. The result indicates that water and raising test temperature can accelerate rutting appearance. The correlation coefficients are over 0.93 when the specimens are in the water at 50 ℃ and in the air at 60 ℃. According to the application of asphalt types, the right test temperatures of B-grade asphalt, A-grade asphalt and modified asphalt are 45 ℃, 50 ℃ and 60 ℃ respectively. The rutting depth of 40 mm-thickness specimen is much larger than that of others, which is not applicable for experiments.The test result of SGC cylindrical specimen has good relationship with that of plate specimen, their correlation coefficient is more than 0.95, so it can be used to evaluate the rut-resistance of asphalt mixture instead of plate specimen.More>
2010, 10(2): 30-35. doi: 10.19818/j.cnki.1671-1637.2010.02.006
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Structure design method of composition airfield pavement
MA Xiang, NI Fu-jian, GU Xing-yu
Abstract: The anti-reflective cracking fatigue life of asphalt course and the fatigue strength of concrete slab were taken as design basis. The structure design methods of the specifications for the cement concrete pavements of civil transport airport and highway were analyzed. The calculated equations of load stress, temperature stress and anti-reflective cracking fatigue life were studied. A structure design method of composition airfield pavement was put forward. Its two design indexes were the synthetic fatigue stress under load and temperature for concrete slab and the fatigue life of anti-reflective cracking for asphalt surface course. During the analysis of design examples, the projects of single layer, double layers and three layers were contrasted. The result indicates that for double layers modified asphalt structure, the fatigue stress is 4.84 MPa, and the anti-reflective cracking fatigue life is 699 362 times, which meets the design requirement of the example, so the project is credible and the structure design method is reasonable.More>
2010, 10(2): 36-40. doi: 10.19818/j.cnki.1671-1637.2010.02.007
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Development of crashworthy movable barrier with pretension wire in tube
YAN Shu-ming, BAI Shu-feng
Abstract: A new type of crashworthy movable barrier was developed with pretension wire in tube structure, the impact condition and safety evaluation specification of movable barrier were analyzed, finite element models were set up and solved by using LS-DYNA explicit software, and the safety performance of movable barrier was proved by full-scale impact tests. Test result indicates that the crashworthiness of movable barrier reaches 160 kJ, and vehicles come back to normal running performance after impact. Barrier maximum dynamic deformation are 972 mm with car impact and 1 093 mm with bus impact, and the simulation results are 913 mm with car impact and 1 100 mm with bus impact. The exit angles of car and bus are 10.2° and 0° respectively, and the simulation results are 9.1° and 0° respectively. The simulation results are coincident with the test results, and the performance of movable barrier meets evaluation specification.More>
2010, 10(2): 41-45. doi: 10.19818/j.cnki.1671-1637.2010.02.008
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Vibration characteristic of coupled system for straddle type monorail beam and train
LIU Yu-yu, GE Yu-mei, YANG Yi-ren
Abstract: Each car of monorail train was idealized as a dynamic system with 15 degrees of freedom and its differential equations were derived by using Lagrange formulation. Track beam was idealized as Euler beam.The governing equations of motion for the coupled system of straddle type monorail beam and train were derived based on the energy method and the concert conditions of the displacements between train and monorail beam. The dynamic responses of the coupled system was studied. The calculated result of dynamic response of monorail beam was compared with the test data at different speeds. The result shows that the effect of train speed on the deflections of beam are less than the effect on the acceleration. The acceleration increases with the increase of train speed and reaches the highest value at 40~50 km·h-1, then decreases with the increase of train speed. Tire model and the beam's surface roughness power spectral density function have greater effect on the calculated result of the lateral responses, and make computation error increase.More>
2010, 10(2): 46-53. doi: 10.19818/j.cnki.1671-1637.2010.02.009
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Parametric design of bogie frame for motive power units based on mechanical method
MI Cai-ying, HU Yi-qin
Abstract: The geometric sizes of bogie frame for motive power units were carried on by using the parametric design based on the mechanical method of structural mechanicst. The procedure was completed by Microsoft Visual C++6.0. According to the primitive parameters of the frame, the specified load and the load cases of the standard UIC 615-4—2003, the allowable stress of material, the overall sizes of the frame and the geometric sizes of different sections were educed, and the biggest nominal stresses of the frame under the load cases were analyzed. Through the comparison of calculational stresses and allowable stresses, the rationality of the frame's structural sizes was inspected. Calculation result indicates that in the design process of the frame, according to the standards UIC 615-4—2003 and EN 13749—2005, under load cases 1~13, the von-Mises stresses are less than 230 MPa, which is the allowable stress of 16Mn material. Under load case 14, the von-Mises stress is less than 345 MPa, which is the yield limit of 16Mn material.The static strength of the frame meets the design requirements.Obviously, the design effectively defines the frame's geometric sizes, and improves the frame's design efficiency.More>
2010, 10(2): 54-58. doi: 10.19818/j.cnki.1671-1637.2010.02.010
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Computational method of engine thrust in aircraft take-off track calculation
SONG Hua-yu, CAI Liang-cai
Abstract: In order to confirm aircraft take-off track, a computational method of engine instantaneous thrust was put forward by using numerical calculation theory.Based on certain engine instantaneous thrusts and thrust curve, the unknown thrusts were calculated by Lagrange interpolation.Two certain aircrafts' take-off tracks were computed when their engine instantaneous thrusts were calculated by the algorithm, and a comparison between computation tracks and actual flight test fitted tracks was made.Comparison result shows that the maximum absolute error of aircraft 1 is not more than 10 m, and the one of aircraft 2 is not more than 35 m.The maximum relative error of aircraft 1 is not more than 3.9%, and the one of aircraft 2 is not more than 8.3%.The result indicates that the algorithm is precise and feasible.More>
2010, 10(2): 59-63. doi: 10.19818/j.cnki.1671-1637.2010.02.011
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Measurement and performance analysis of switch signal for automotive electrical acceleration pedal
LIU Rong-xian, MA Ming-xing, YE Fei
Abstract: A test system of automotive electrical acceleration pedal was designed based on non-contact angle replacement sensor and the output characteristics of idle switch due to stampeding speeds and sampling frequencies. With ADLink-PCI911DG acquisition card, PCI-DAQ virtual instrument technology and LabVIEW software, the angle sensor signal was transferred by A/D, was driven by DAQ, and the data acquisition was realized automatically. The key factors that affected the switch signal of electrical acceleration pedal were analyzed under fast press and fast release, fast press and slow release, slow press and fast release, slow press and slow release.The result shows that the speeds and frequencies are main influence factors, and the sampling frequencies are not less than 1 000 Hz to ensure measuring precision. The measuring errors are minimal under slow press and slow release, and the errors are maximal under fast press and fast release. Based on the result, some error reasons and solving measures are proposed.More>
2010, 10(2): 64-68. doi: 10.19818/j.cnki.1671-1637.2010.02.012
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Automotive ABS control strategy based on logic threshold
ZHENG Tai-xiong, MA Fu-lei
Abstract: In order to solve the impact of the estimated accuracy of automotive reference speed on logic threshold control method, automotive reference speed was estimated by using correctional peak-to-peak connection method, and an automotive ABS control strategy was put forward. In the strategy, automotive slip ratio was main control threshold and automotive acceleration was secondary control threshold. A control test was carried out on the road with high attachment coefficient. Test result shows that at 45 km·h-1, the curves of automotive reference speed and real speed match, the maximal error is 6.4%, and the average error is less than 1.6%. Automotive braking time is 3.2 s, the braking distance is 15 m, and the average deceleration is 3.9 m·s-2. Obviously, the control effect is good and the control strategy is credible.More>
2010, 10(2): 69-74. doi: 10.19818/j.cnki.1671-1637.2010.02.013
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Layout optimizing model of external passenger transport hub in metropolis
LI Xu-hong, XIAO Wei-zhou, CHEN Da-wei, XU Zhong, ZHU Yan-dong
Abstract: The features of external passenger transport hub were analyzed, and a bi-level planning model of hub layout was established from the views of transport policy-makers and users. The upper-level model was from the perspective of policy-makers, its target was the minimum of time consumptions of all travelers by optimizing hub layout, and it was solved by genetic algorithm. The lower-level model was from the perspective of users, the traveling characteristics of passengers were described, the rational routes of passengers were arranged by adopting stochastic user equilibrium model, and the lower-level model was solved by the method of successive averages. Example result indicates that under the constraints that three, four or five transport hubs are allowed to be constructed at most, the optimal fitness of the model reaches a constant value with 100 generations of evolution, and its convergence rate is fast, so the bi-level planning model is valid.More>
2010, 10(2): 75-81. doi: 10.19818/j.cnki.1671-1637.2010.02.014
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Route planning of regional emergency evacuation based on lane modeling
WANG Jian, HU Xiao-wei, TONG Jing-jing, HE Lei
Abstract: In order to effectively solve the potential delay during emergency evacuation routes, a lane-based network flow model was presented, its objective was the minimum of whole evacuation cost, and its constraint conditions were eliminating crossing-conflicts, reducing confluence, flow conservation and non-negative, restricting the traffic capacities of nodes and arcs. The expansion network flow model based on lane level and the traditional node-arc network model based on road level were solved by adopting Lingo software respectively, and a network including four intersections was analyzed as an example. Analysis result indicates that compared to the traditional network model, the travel cost saves four hours per vehicle, and reduces by 25% through the lane-based extension network flow model, so the model can minimize evacuation cost, reduce delay caused by merging and crossing, and improve evacuation efficiency.More>
2010, 10(2): 82-87. doi: 10.19818/j.cnki.1671-1637.2010.02.015
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Traffic characteristics of medium city in fast urbanization area
SHI Xiao-fa, YU Jun-hao
Abstract: In order to analyze the traffic flow space-time distribution characteristics of medium city in fast urbanization area, vehicle class composition, the temporal and spatial distribution characteristics of traffic flow, and road network characteristics were statistically studied based on the traffic flow survey data of comprehensive transportation planning for Dongguan in 2008. The traffic load of base road network was comprehensively evaluated by using traffic planning software TransCAD.The current traffic situation in Dongguan was anatomized. The traffic development strategies of medium city were put forward. Analysis result indicates that the trip proportion of car is very high, the development of public transportation lags behind, transport infrastructure has a serious shortage, the mixed running phenomenon of passenger-freight traffic and transit traffic is serious in access points, road network structure is defective, and road function is not clear in medium city. Traffic strategies are suggested, including improving road network system, optimizing the structure of urban traffic, building efficient public transport system, regulating traffic management, and coordinating transportation and land use.More>
2010, 10(2): 88-94. doi: 10.19818/j.cnki.1671-1637.2010.02.016
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Optimal algorithm of unpaired locomotive working diagram with compact return locomotives at return station
XIE Jin-bao
Abstract: One kind of plotting algorithm of unpaired locomotive working diagram was discussed. At locomotive return station, the network flow model was applied to figure out the scheme of paired locomotive working diagram, the diagram meeted the optimal requirements on unpaired locomotive working diagram, and could assign residual locomotives to their nearest train paths respectively. At locomotive home station, the departure or arrival time of train path with extra return locomotive was inserted into the list of train departure or arrival time, and the unpaired locomotive working diagram was transferred to paired locomotive working diagram, and the assigning problem of paired locomotive working diagram was solved by using searching-optimization-at-form method.Analysis result shows that when the unpaired factor is 0.78, and the locomotive staying time standards at both of station ends are same, the proportion between the general staying time of locomotive home station and that of locomotive return station is no less than 1.25. The extra staying time of locomotive at return station is further transferred to home station by using the optimal algorithm, so the locomotive can compactly return at return station.More>
2010, 10(2): 95-98. doi: 10.19818/j.cnki.1671-1637.2010.02.017
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Saving algorithm of multi-vehicle routing problem with pickup-delivery and soft time window
QI Wen-xiang, LU Zhi-qiang, SUN Xiao-ming
Abstract: Multi-vehicle routing problem with pickups and deliveries was studied, and soft time window constraint was considered by adding time punishment cost. The mathematical model was built, and its optimized object was the minimum of combination with vehicle rent cost, transportation cost and time punishment cost, and the model was solved by using heuristic saving algorithm. Time punishment cost and transpiration cost were calculated respectively, and the relation between direct and indirect deliveries was compared to obtain best routes. Test result indicates that when the times of pickups and deliveries reach 50, the average loading rate of freight car still achieves above 80%, so the heuristic saving algorithm can reduce the distance without loadage and rent times, and optimize total cost.More>
2010, 10(2): 99-103. doi: 10.19818/j.cnki.1671-1637.2010.02.018
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Relationship between fatigue driving and traffic accident
LI Dou-hou, LIU Qun, YUAN Wei, LIU Hao-xue
Abstract: Based on the statistics of road traffic accidents at home and abroad, the driver characteristics in fatigue driving, the time period distribution of accidents, and the main reasons of highway accidents were analyzed respectively. The effect of fatigue driving on operating actions and the reason of driver fatigue were studied, and the preventive measures of fatigue driving were put forward. Analysis result shows that male drivers under 30 years of age, the peoples with less than 3 years of driving ages and the peoples with about 10 years of driving ages are the colony who have more fatigue driving accidents than others. Most fatigue driving accidents happen approximately at 2:00 to 6:00 and 15:00 to 16:00, and the accident scales caused by fatigue driving on expressway are more higher than that on ordinary road.The causes of fatigue include prolonged driving, lack of sleep, circadian rhythms and driver factors.In order to prevent fatigue and reduce fatigue driving accidents, drivers are suggested to have sufficient sleep, a short rest, reasonable arrangements for travel time, and use fatigue warning devices.More>
2010, 10(2): 104-109. doi: 10.19818/j.cnki.1671-1637.2010.02.019
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Public transit pricing and optimal government compensation models
YANG Fan, YANG Qi, ZHANG Jun, XI En-chong
Abstract: In order to improve public transit pricing and government compensation mechanism, three potential economic principles such as increasing returns to scale, positive externalities and second-best theory were elaborated. Three models for pricing and calculating optimal compensation were established. The application of public transit pricing and compensation models was studied with Xi'an as an example. Analysis result indicates that the pricing and compensation model of marginal cost based on increasing returns to scale is identified as best social welfare and being the most practical, another model of supply-demand balance based on positive externalities can get optimum corporate welfare, and the model of Ramsey pricing and compensation based on second-best theory is better for explaining principles. The government compensation amount of Xi'an in 2009 is calculated at 978 million yuan, the outcome basically agrees with the actual demand, and the models are effective.More>
2010, 10(2): 110-115. doi: 10.19818/j.cnki.1671-1637.2010.02.020
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Traffic incident acoustic recognition method based on wavelet decomposition and support vector machine
LUO Xiang-long, GAO Jing-huai, NIU Guo-hong, PAN Ruo-yu
Abstract: The existing automatic detection and recognition methods of traffic incidents were analyzed, a recognition method with vehicle acoustic signals was proposed based on wavelet decomposition(WD) and support vector machine(SVM). Vehicle acoustic signals were decomposed with WD, the powers in different frequencies were regarded as different incident eigenvectors, and the traffic incident classifier composed of multiple SVMs was trained. The acoustic signals of normal driving, braking and crash incidents were recognized. Test result shows that various traffic incidents can be recognized with vehicle acoustic signals, the recognition rate reaches 95%, so the proposed method is feasible.More>
2010, 10(2): 116-121. doi: 10.19818/j.cnki.1671-1637.2010.02.021
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Parameter selection of support vector machine based on stepped-up chaos optimization algorithm
LI Dong-qin, WANG Li-zheng, GUAN Yi-feng, XU Hai-xiang
Abstract: In order to analyze the parameter selection of support vector machine (SVM), penalty coefficient, insensitive coefficient and width coefficient in radial basis function (RBF) were used as optimization variables, the former searching formula was changed, and the third searching time was added. A new improved stepped-up chaos optimization algorithm (ISCOA) was proposed by adopting the Chebyshev mapping instead of Logistic mapping to form initial chaos serial. The new algorithm was used in artificial data set and real data set, and was compared with traditional cross validation method. Test result indicates that the running time is cut down at least 23.43%, and the precision improves at least 6.31% by using ISCOA in artificial data set. The predicted value is more close to real value, and the relative errors are controlled under 3.13% in real data set. So ISCOA has higher prediction precision and optimization effect.More>
2010, 10(2): 122-126. doi: 10.19818/j.cnki.1671-1637.2010.02.022
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