交通运输工程学报

Simulation of semi-active and active controls for pantograph-catenary vertical vibrations

LUO Ren, CENG Jing

Abstract: In order to improve the vertical dynamics performance of pantograph for high-speed train, the nonlinear vertical dynamics model of pantograph, the vertical finite element dynamics model of catenary and the dynamics model of vehicle were set up.Pantograph-catenary coupled vibration and track irregularity excitation were taken into account, the displacement and velocity of the top point of pantograph frame or pantograph head were taken as feedback control signals, and active control actuator or semi-active control damper was mounted between the base and the frame of pantograph.The numerical simulation method was used to study the semi-active and active controls of pantograph-catenary vertical coupled vibrations, and the control effects were compared.Comparing with passive system, the standard deviation of pantograph-catenary contact force decreases at least 26.84% when train speed is 250 km·h^-1, and decreases at least 20.88% when train speed is 300 km·h^-1.So pantograph-catenary vibrations and contact force fluctuation at low frequencies are reduced evidently by using semi-active and active controls, current collection quality is improved, semi-active control is simple and easy to realize, and it will not affect the original dynamics performance of pantograph even if the control is disabled.More>

2008, 8(4): 1-6.

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Effect of bracing stiffness on property of friction and wear with electrical current

DONG Lin, CHEN Guang-xiong, ZHU Min-hao, ZHOU Zhong-rong

Abstract: In order to prolong the use life of frictional pair, the effect of bracing stiffness on the tribological characteristic of aluminum-stainless steel composite conductor rail and collector shoe with electrical current was studied by using the modified jig of CETR UMT-2 tester, normal forces changing with time, the wear mass losses of collector shoe specimens and the deformation energy of spring during loading and unloading process were measured, and the relation between the energy and the characteristic was analyzed.The result shows that the vibration amplitude of normal force increases with the decrease of normal force; the vibration amplitude of normal force and the wear mass loss in elastic bracing system are less than those in rigid bracing system; the larger the ratio of frictional energy to deformation energy for spring is, the stronger the ability of absorbing vibration is, the lower the vibration amplitude is, and the less the wear mass loss is.Obviously, elastic bracing decreases the vibration amplitude of normal force, and ensures better traction power supply, so the appropriate range of normal force and the rational stiffness of spring are necessary to decrease the wear mass loss induced by arc erosion, and to prolong the wear life of frictional pair.More>

2008, 8(4): 7-10.

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Choosing method of unloading velocity of hydraulic damper for railway vehicles

DAI Huan-yun

Abstract: In order to accurately choose the unloading velocity of hydraulic damper for railway vehicle, a 2σ method was proposed.The relative velocity of the damper was obtained by test and dynamics simulation, and probability statistical analysis, parameter estimation and probability distribution inspection were processed.Based on the normal distribution feature of the relative velocity, the 2σ value of the relative velocity was taken as the unloading velocity.The simulation result indicates that 95% of low frequency vibrations are damped, and 5% of high frequency vibrations are filtered by using the damper with the unloading velocity determined by the method.More>

2008, 8(4): 11-15.

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Vehicle vibration model based on effective road profiles

ZHANG Wei, WEI Lang, YU Qiang

Abstract: In order to effectively analyze the actual contact process of tire with road surface, tire was simplified as a rigid circle, current effective road profile was changed from the center track of wheel to the rock bottom track of wheel, its general equations were set up to solve new effective road profiles, a vehicle vibration model with 2 degrees of freedom was presented, effective road profiles were regarded as road surface input, and the simulation and experiment of vehicle ride comfort were done.Analysis result shows that the simulation result of vibration accelerations for vehicle axle and body approaches to road experimental data.Under effective road profiles input, the average relative error of vehicle axle acceleration is 5.17%, and the average relative error of body acceleration is 1.71%.Under real road profile input, the average relative error of axle acceleration is 12.93%, and the average relative error of body acceleration is 28.48%.More>

2008, 8(4): 16-19.

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Combustion characteristics of electronic fuel injection gasoline engine fueled with methanol-gasoline blends

QI Dong-hui, CHEN Hao, REN Xue-cheng

Abstract: In order to study the effects of methanol-gasoline blends with different methanol ratios on the heat releasing rule of multi-point electric fuel injection gasoline engine, the recorded cylinder pressure of the engine was used to compare and analyze the variation rules of combustion characteristic parameters under the running conditions of the engine.Analysis result indicates that at middle and low engine speeds, the maximum cylinder pressure and the peak of pressure rising rate of blends engine are almost similar to those of gasoline engine under middle and light engine loads, and slightly higher under high engine loads; at high engine speeds, the peak pressure and the pressure rising rate of blends engine are evidently higher than those of gasoline engine.Compared with gasoline engine, the ignition delay period of the engine is longer under all range of loads; the combustion duration of the engine is shorter under light loads, and is the same under middle and high engine loads; the peak heat releasing rate and cyclic variability coefficient are slightly higher under middle and light loads, and are similar under high loads.There is not evident influence of engine speed on the varying trand of chmbustion characteristic parameters with the ratio of methanol in blends.More>

2008, 8(4): 20-24.

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Generation and extension methods of 3D atmospheric turbulence field

GAO Zhen-xing, GU Hong-bin, LIU Hui

Abstract: In order to improve the real-time flight simulation fidelity of aircraft through turbulence field, the generation and extension methods of 3D atmospheric turbulence field were put forward.Based on Von Karman model, spatial turbulence field was generated in frequency domain by using Monte Carlo method and transformed back to time domain by using 3D Fourier inverse transform.The conjugate characteristic of Fourier transform was applied to guarantee the realism of turbulence field in time domain.During flight simulation, the integral scale and intensity of turbulence field changed with flight altitude by dimensioning the non-dimensional turbulence field which had been generated in advance.A symmetrical turbulence extension method was presented to make sure that the local field could be effectively extended to wide range and continuous field.Simulation result indicates that turbulence field conforms to Von Karman model before and after symmetrical extension, compared to the generation method based on correlation function matrix, the new algorithms have faster generation speed and less storage space, so they are suitable for real-time flight simulation.More>

2008, 8(4): 25-29.

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Shrinkage properties of cement stabilized macadam reinforced with polypropylene fiber

ZHANG Peng, LI Qing-fu, HUANG Cheng-kui

Abstract: In order to decrease the shrinkage of cement stabilized macadam, the influences of polypropylene fiber on the shrinkage properties of cement stabilized macadam were studied, its dry shrinkage property was measured by using micrometer gauge method, and its thermal shrinkage property was measured by using strain gauge method, the rules of its average dry shrinkage coefficient and average thermal shrinkage coefficient with the variation of the fiber volume content were analyzed.Test result shows that the addition of polypropylene fiber can observabley decreases the average dry shrinkage coefficient and average thermal shrinkage coefficient, the average dry shrinkage coefficient of long curing period is smaller than that of short curing period, while the average thermal shrinkage coefficient of long curing period is larger than that of short curing period.When the fiber volume content is less than 1‰, the average dry shrinkage coefficient and average thermal shrinkage coefficient observably decrease with the increase of polypropylene fiber dosage.So cement stabilized macadam reinforced with polypropylene fiber has favorable resistance on dry shrinkage and thermal shrinkage when the fiber volume content is appropiate, and its application in base course can improve the anti-cracking performance of pavement.More>

2008, 8(4): 30-34.

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Research on zero shear viscosity of asphalt based on different loading modes

MENG Yong-jun, ZHANG Xiao-ning, JIA Juan

Abstract: In order to obtain rational indexes for appraising the high-temperature performance of asphalt, dynamic loading test and static loading test of asphalt were made, the difference of zero shear viscosity(ZSV) was analyzed under different loading modes, the applicability and feasibility of ZSV were studied, the influence of different rheological models on the fitting parameters of asphalt at high temperature was evaluated.Analysis result shows that the ZSV value of base asphalt can be got by extrapolating the figure scanned by dynamic frequency, while modified asphalt can't enter into viscosity flow state at low shear rate, so its ZSV can't be got directly by extrapolating the figure.ZSV values fitted from static loading are smaller than that from dynamic loading, while the values fitted from dynamic loading based on Carreau model and from long-time static loading based on discrete retardation spectrum have a good correlation, and both of them can be used together as high-temperature indexes of asphalt.More>

2008, 8(4): 35-39.

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Mechanical behaviors of cement concrete pavement structure under impact rolling load

HU Chang-bin, QUE Yun

Abstract: In order to explain the mechanical behaviors of cement concrete pavement structure under impact rolling load, four typical loading positions were considered such as slab longitudinal side, slab transverse side, slab corner and slab center, the stress and deformation characteristics of pavement structures under the impact load of quadrilateral impact roller were studied based on 3D elastic-plastic dynamic finite element method.Analysis result indicates that the main reasons of old cement concrete pavement cracking in different cases are that the bottom of cement concrete pavement bears longitudinal flexural-tensile stress and transverse flexural-tensile stress, both base course and old slab appear flexural-tensile state in two directions, while subgrade is in three dimension compressive stage, and the effective influence depths are different in different cases.The vertical displacements of slab and influence depths are maximum when the load locates at slab corner, while the vertical displacements of slab are minimum and uniform when the load locates at slab center.Pavement slab is in longitudinal bending stage and easily forms transverse cracks when the load locates at slab center, while pavement slab is in transverse bending stage and easily forms longitudinal cracks when the load locates at slab side.So the cracking effect is a synthetic function of foundation stiffness, impact energy and impact location, it is reasonable that constructing scheme is chosen according to different road conditions.More>

2008, 8(4): 40-46.

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Load stress analysis of concrete base for durable asphalt pavement with 3D finite element model

ZHENG Mu-lian, MA Qing-lei, CHEN Shuan-fa, WANG Song-gen, WANG Bing-gang

Abstract: In order to analyze the influence of some factors on the load stress of concrete base for durable asphalt pavement, a 3D finite element model was built, the calculation parameters of the model were determined, they were arranged by using orthogonality design method, the load stress at the bottom of concrete base was calculated, and the maximum difference and variance of the calculation results were analyzed.Analysis result shows that the load stress of concrete base decreases slightly with the thickness increase of asphalt surface, decreases with the thickness increase of concrete base, increases with the modulus increase of concrete base, and decreases notably with the modulus increase of subground, while there is little influence of surface course modulus on the load stress; the prominent influence factors of the load stress are subground modulus, concrete base modulus and thickness when the confidence probability is 95%, while the prominent factors are subground modulus, concrete base modulus and thickness, surface course thickness when the confidence probability is 90%, and the prominence of each factor decreases in turn.More>

2008, 8(4): 47-51.

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Numerical analysis of fatigue crack propagation in asphalt pavement on steel deck

CHEN Tuan-jie, HUANG Wei, WANG Shuang-jie

Abstract: In order to discover the crack mechanism of asphalt pavement on steel deck, the resistance curve of fatigue crack propagation was simulated, the whole process of crack beginning, propagation and instability was analyzed based on 3D finite element method and experiment data.Analysis result shows that the form of resistance curve depends on the type of material and the composite beam of pavement and steel plate.When the natural crack length is 0, the propagation of fatigue crack has 3 phases such as initial propagation zone, stable propagation zone and unstable propagation zone, and the total fatigue life almost reaches 8 million times; when the natural crack length is 10 mm, the propagation of fatigue crack in asphalt pavement may start from unstable propagation zone, the total fatigue life may be 2 million times; there is a good nonlinear relationship between crack increment ratio and loading times.So for steel deck pavement, the materials with little porosity and good dense degree should be selected, and fatigue crack propagation phase can be judged by loading times.More>

2008, 8(4): 52-57.

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Calculation method of economic evaluation indices for highway engineering project

XUE Xiao-rong

Abstract: To effectively evaluate the alternatives of highway engineering project with fuzzy basic data and parameters, an economic evaluation indices system was set up, the indices were proposed as trapezoidal and triangular variables, their fuzzy calculations were completed in the same or different possible spaces, the membership of every index was gained by using Zadeh's expansion principle, the credibility value, key value and expectation value of every index were computed by using fuzzy simulation technique, and the alternatives were evaluated based on the computation values.Evaluation result shows that the fuzzy expectation net present value of the alternative is more than 0, the credibility value is 100%, so the alternative is feasible, and the outcome of the evaluation is objective.More>

2008, 8(4): 58-60.

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Method of construction error control for cantilever-casting cable-stayed bridge

WANG Jing-feng, XU Xing, XIANG Yi-qiang

Abstract: During the cantilever-casting construction of prestressed concrete(PC) cable-stayed bridge, in order to reduce the errors of cable tension and line shape, the error cause and present situation of control means were analyzed, and the control methods of model error and cantilever-casting simulation error were discussed.With the combination of 3D isoparametric element and shell element, degenerated solid element was proposed for the spatial analysis of complex PC bridge, and discrete bar model was set up.According to the deformation compatibility condition of traction cable's anchorage, the increment of cable tension during casting concrete was computed, and the calculation formula of traveler's front level was educed.Application result indicates that the control precision of trailing cable tension is within 3%, the control precision of final cable tension is within 5%, and the error of traveler's front level is within 1 cm.Therefore, the cable tension and line shape of PC cable-stayed bridge under all construction conditions can be well predicted by the proposed method.More>

2008, 8(4): 61-67.

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Calculation models of capacity and delay for closely spaced parallel runway

GUO Hai-qi, ZHU Jin-fu

Abstract: In order to accurately assess the capacity and delay of closely spaced parallel runway, a time-space diagram was established in accord with realistic operational features, the calculation models of the capacity and delay under the classic mixed operation mode of single runway were referred, departure flights were allowed in the intervals of arrival flights, double queue system theory and logical discursion method were utilized, the calculation models of the capacity and average delay for closely spaced parallel runway were built separately, simulation method was used to check the models, and the calculation result and the simulation result were compared.Comparison result shows that the differentia rate of runway capacity is 0.58%, the maximum differentia rates of the average delay and queue are 1.7% and 1.4% respectively, so the new models reflect the realistic operational situation of closely spaced parallel runway, and are feasible.More>

2008, 8(4): 68-72.

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Optimization model of spare parts inventory for civil aircraft based on marginal utility

NI Xian-cun, ZUO Hong-fu

Abstract: In order to maximize the guaranteed effect of spare parts for civil aircraft and optimize the inventory level of each item, an optimization model of the inventory was presented to optimize the mean maintenance latency time of aircraft, the provision cost of total spare parts was taken as the constraint of the model, and the technical characters, economic characters and provision parameters of spare parts were taken into account.A heuristic algorithm was given to solve the model based on the marginal utility analysis of spare part unit cost, so that the optimum project of the inventory was found.Compared with the result calculated by item approach, the mean latency time caused by the shortage of spare part is shortened by 11.5%, and spare part budget is reduced by 27.5%, so the model is validate and effective to economize inventory cost and improve the use level of aircraft.More>

2008, 8(4): 73-76.

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Approximate mean value analysis method of maintenance ability for civil aeroengine maintenance workshop

TANG Xin-min, HAN Song-chen

Abstract: To evaluate the scale of aeroengines fleet under the available maintenance capacity of civil aeroengine maintenance workshop, an approximate mean value analysis method of the maintenance ability was proposed.The transferring model of aeroengine in the workshop was built by using extended stochastic Petri net, multi-level maintenance service performance indexes were revised by using single level performance indexes, squared variation coefficient method was used to approximate service time with normal distribution, and the evaluation results of the ability by using approximate mean value analysis method and simulation method were compared.The result indicates that the maximal relative error of queuing length for maintenance sections is 9.14%, part checking, handcrafted repairing and mechanical machining are the bottlenecks of the workshop performance, so the method is proved to be efficient.More>

2008, 8(4): 77-83.

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Principles and its prototype algorithm for dual shortest path tree in networks with turning constraints

REN Gang, WANG Wei

Abstract: To analyze the difference and similarity between the shortest path characteristics and searching algorithms with and without turning constraints, dual graph theory was studied, the spanning tree of dual network was constructed with the shortest path set from a source node to all arcs in turning constraint network, the concept of dual shortest path tree(DSPT) was put forward and used for algorithm comparison.Analysis result shows that the present solution methods with turning constraints, including arc-labeling algorithm, node-labeling algorithm and dual-network method, can be unified into the same DSPT algorithmic frame, and have the same path searching strategies as the shortest path tree(SPT) algorithm without turning constraints; a prototype DSPT algorithm can be developed for the shortest path problem in networks with turning constraints, and more efficient algorithms can be designed according to different SPT labeling techniques.More>

2008, 8(4): 84-89.

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Evolution of day-to-day route choice behavior considering risk aversion and perception updating

LIU Tian-liang, HUANG Hai-jun, CHEN Jian

Abstract: In order to depict travelers' day-to-day route choice behaviors, an integrated model considering risk aversion and perception updating was proposed by using dynamics system approach and fixed point theory, its evolution stability was discussed and validated in a simple network.It is pointed that travel time budget, expected route travel time, actual route travel time and route flow appear a large of turbulence in 15 d at the beginning of simulation, but the traffic pattern evolves to stochastic user equilibrium state after nearly thirty days' travel.Analysis result indicates that the route choice evolution adopted in the model is highly similar to the computational steps of the classical method of successive average(MSA), so the evolution stability can be assured, and the final flow pattern is independent of initial values of all state variables.More>

2008, 8(4): 90-94.

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Travel time estimation method in urban road network with signal control

HE Zhao-cheng, ZHAO Jian-ming, WANG Zhen-bo, WEI Qing-bo

Abstract: In order to precisely monitor the dynamic travel time in urban road network with signal control, the fluctuation rule of traffic volume affected by signal control strategy was analyzed, and a travel time estimation method based on traffic volume diagram offset was proposed.The similarity of traffic volume diagrams under different cross sections was analyzed, the dynamic travel time between cross sections was computed according to the offset of traffic volume diagram when the maximum similarity was reached, and it was compared with the field survey data.Comparison result indicates that the maximum mean relative error of mean travel time is 7.1% for different time lengths (5, 10, 20 min) during peak and non-peak periods at the closed road segments of urban road network, so the method is feasible.More>

2008, 8(4): 95-98.

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Feedback controller design and algorithm of freeway system

XIE Jing-song, HAN Yin, FAN Bing-quan, GAN Hong-cheng

Abstract: In order to improve the using efficiency of freeway system, a feedback controller was designed and its iterative algorithm was proposed, the controller could track vehicles' real-time densities and compare them with the anticipant density, then it sent the errors to the vehicles, and guaranteed the convergence of the real vehicle density to the anticipant density under appropriate speed command followed by vehicles.Simulation result indicates that the maximum relative error of vehicles' densities and travel speeds is 0.32%, and the average time consumption is 0.32 s after the fourth iteration of the algorithm, so the controller guarantees the smooth and stable traffic flow, reduces the vehicle's delay and increases the efficiency of the system.More>

2008, 8(4): 99-103.

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Calculation method of reliability for driving behavior based on monotone coherent system

LIU Yu-zeng, GUO Zi-zheng, ZHANG Jun

Abstract: In order to evaluate the reliability of driving behavior, a calculation method was put forward, with the combination of human-machine system reliability theory and driving behavior chain, a reliability diagram was constructed which included sensitivity, judgment, operation elements and their modules, the reliability test and calculation method for every apparatus element were ensured, the reliability quantitative models for function modules and driving behavior system were calculated based on monotone coherent system theory, the probability importances of every physiological and psychological elements were computed, and their influence degrees on driving behavior were analyzed.Computation result shows that there is an obvious reliability difference between accident group and non-accident group, non-accident group has better reliability than accident group, its whole reliability shows a downward trend, the drivers' whole operation stabilities in accident group are worse; the impact of physiological factor on driving behavior reliability is larger in the pre-period than the latter period, while psychological factor is opposite.More>

2008, 8(4): 104-109.

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Optimal structure parameters of interrupted type straight-road concrete barrier with given length concrete frusta

LEI Zheng-bao, HOU Shi-jing, ZHOU Zhi-gang, YU Jin-xiu, PENG Zuo

Abstract: In order to obtain the optimal structure parameters of interrupted type straight-road concrete barrier with given length concrete frusta, the orthogonal experimental design method was used, 5 section parameters of the barrier were taken as design variables, each design variable had 5 levels, based on vehicle-barrier collision system dynamics model and LS-DYNA software, vehicle-barrier collision simulation test with 25 group section parameter combinations was carried, and the influence of section parameter combinations on vehicle collision was studied.Simulation result shows that the barriers with 2 group section parameter combinations meet the collision requests that tire and barrier are intact, the head injury criterion is less than 1 000, the barrier has a strong energy-absorption capacity, and can guide the vehicle out of control to the right direetion as long as its design parameters are reasonable, so it has good characteristics for engineering application.More>

2008, 8(4): 110-115.

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Study of transportation and strategy of energy and environment in China

MA Tian-shan, FAN Yi-jiang

Abstract: In order to guide the energy saving and exhaust reducing in transportation, the characters of transportation energy consumption and environmental pollution were analyzed, the status of transportation in energy and environment strategy in China and the significance to carry out the energy saving and exhaust reducing in transportation were discussed, and the targets and key measures of the energy saving and exhaust reducing were pointed.Study result shows that strengthening the energy saving and exhaust reducing in transportation not only increases the direct financial benefit for transportation enterprises, but also brings a large amount of direct and indirect social benefit for transportation areas even for whole country, moreover accelerates the harmonious development between society and environment, so it should be recognized from the strategic angle of national continuance development.More>

2008, 8(4): 116-120.

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Assessment framework design of land intensive use for highway construction

HAN Xiao-yu, WU Qun-qi

Abstract: In order to relax the contradiction between the land requirement of highway construction and the lack of land resources, the conception and connotation of land intensive use for highway construction were analyzed, the nature, purpose and indices-selecting principles of land intensive use assessment were studied, and an assessment framework was put forward.Analysis result shows that the indices-selecting principles should include systematization, predictability, variability, particularity, manipulation and standardization, the design requirements of assessment framework are the high efficiency, justice and coordination of sustainable development for the whole land-using system of highway construction, the train of design thought is the structure rationalization, optimum function and best integrated effectiveness of land use for highway construction, which may improve the sustainable development of highway construction.More>

2008, 8(4): 121-126.

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