交通运输工程学报

Dynamic characteristic of new hydro-pneumatic buffer for railway vehicle

HUANG Yun-hua, LI Fei, FU Mao-hai, LIAO Xiao-ping

Abstract: In order to improve the safety-impacting speed of freight organized into groups' spot and manipulating vehicle efficiency, a new type of hydro-pneumatic buffer for railway vehicle was developed, its basic structure and principle were summarized, a lognitudinal dynamics calculating model of train with the buffers was established, the dynamic characteristic of the buffer was analyzed by numerical simulation method. The calculating result shows that the buffer capability may reach 160 kJ, and its absorptivity may exceed 90% in the condition that the biggest impedance force of the buffer is no more than 2200 kN as manipulating vehicle, the impacting speed of manipulating vehicle is increased, the lognitudinal impulsion and libration between vehicles are decreased and dissipated, the hydro-pneumatic buffer may be adapted to the request of heavy loading and speed increasing train.More>

2005, 5(4): 1-5.

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Probabilistic model of random-long fatigue crack propagation rates

ZHAO Yong-xiang, YANG Bing, ZHANG Wei-hua

Abstract: For the reasonable-probabilistic safety assessment in entire stress intensity factor range, a probabilistic model was presented for characterizing the random-long fatigue crack propagation rates covering the factor range from threshold to fracture roughness. Based on the rates following lognormal distribution, the effects of the scattering regularity of test data and sampling size on the probabilistic assessment were taken into account, and the survival probability and the confidence were coupled in the model. The parameters of the model were measured by linear regression technique and maximum likelihood method. The model was applied to analyze the test data of LZ50 axle steel about Chinese railway vehicles. The result indicates that the entire random process of long fatigue crack growth from crack initiation to fracture can be mathematically described by the model, the correlation coefficient of the model is maximum compared to Paris, Elber and Forman models.More>

2005, 5(4): 6-9.

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Vertical vibration isolation and suspension parameter optimization of railway vehicle

HAO Jian-hua, CENG Jing, WU Ping-bo

Abstract: In order to provide a new and efficient method for the selection of vertical suspension parameters of railway passenger car, an extended Ruzicka vibration isolation model of the vertical suspension system was set up, and the harmonic vibration isolation properties of the system were investigated, the optimization method of multiple aims and multiple parameters for the system was carried out by evaluation function method so that the minimum vertical displacement and acceleration of carbody could be obtained. Numerical computation result indicates that the values of optimized result with multi-aim method are much better than the values with single-aim method, the final optimized parameters are related with the optimization aims, and different optimization results are achieved with different optimization aims.More>

2005, 5(4): 10-14.

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Dynamic performances of small-radius curved track for mountain strengthened railway

WANG Kai-yun, ZHAI Wan-ming, LIU Jian-xin, FENG Quan-bao, CAI Cheng-biao

Abstract: New strengthening technologies of laying concrete sleeper and matching measurement have been adopted to raise train speeds on the small-radius curved tacks of Chinese mountain railways. In order to investigate the dynamic performances of the curved track structure, the dynamic properties of the strengthened track and the unstrengthened track were compared based on system engineering theory and vehicle-track coupling dynamics. Analysis result shows that the dynamic interaction between wheel and rail and the rail-pad force of the strengthened track are little bigger than those of the unstrengthened track, the safety grades of the tracks are same, the strengthened track can benefit to decrease the displacements of all components of track structure obviously, to restrain the deformation of track effectively, and to reinforce the stability of railway, especially the lateral displacement and the gauge enlargement of the strengthened rail are about 33% of original rail. Furthermore, the strengthened track can help to reduce the vibration of the sub-rail structure and to lighten the destruction of track caused from raising train speeds.More>

2005, 5(4): 15-19.

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Traction calculation model of urban mass transit

SHI Hong-guo, PENG Qi-yuan, GUO Han-ying

Abstract: In order to optimize the single-particle model of urban mass transit traction calculation system and make traction calculation result more accurate, the optimized multi-particle simulation model was built up. Train was regarded as a dynamic chain made of multiple particles so that every car could be analyzed, train length influence on its adjunctive resistance was considered. Optimization shifting gears, rational selection freewheeling position and control the range of velocity fluctuation were adopted to improve the model calculation veracity, train braking position was searched through reverse recursion method. The computation results of the optimized traction calculation model and single-particle model show that the average velocity is raised by 5%~20%, the start velocity is decreased by 5%~25% in pulling into station process, the energy consumption is decreased by 5%~20%, the model is feasible.More>

2005, 5(4): 20-26.

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Rational range determination of key sieve pores for graded crushed stone based on shear performance

MA Biao, MO Shi-xiu, WANG Bing-gang

Abstract: Using the flexible material shear performance tester, the shear performance of graded crushed stone was tested, the influences of variety sieve pores and their passage rates on the shear performance were analyzed. The shear strength of graded crushed stone changes as parabola trend with the passage rate increasing of the pores 4.750 mm and 0.600 mm, it waves as horizontal inverse "S" curve with the passage rate increasing of the pore 2.360 mm, it gradually increases as a whole with the passage rate increasing of the pore 0.075 mm. The result indicates that the sieve pores, including 4.750, 2.360, 0.600 and 0.075 mm, should be regarded as key sieve pores for graded crushed stone, whose maximum grain size is 31.5 mm and the index of the Taibol formula is 0.5, for the control index that the shear strength exceeds 520.5 kPa, the rational change ranges of the key sieve pores passage rates based on the shear performance are recommended, the change ranges of the rational passage rates including the sieve pores 4.750, 2.360, 0.600 and 0.075 mm are 35%~44%, 22%~37%, 10.0%~17.5% and 2.0%~7.5% respectively.More>

2005, 5(4): 27-31.

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Durabilities of polymer cement materials in highway engineering

LI Zhu-long, WU De-ping, ZHANG Ya-zhou

Abstract: In order to study the durabilities of polymer modified cement materials in road engineering, the split-strength of polymer modified cement mortar(PMCM) was studied by split test, the wearability of PMCM was studied by grinding test, the corrosion-resisting of PMCM dipping in different acidity liquors was studied, the contraction coefficient of PMCM and PMCC(polymer modified cement concrete) was studied by thermal and dry-contraction coefficient test, the frost-resisting of PMCC was studied by frost-melt cycle test, the anti-permeability of PMCC was studied by permeability test. Compared to cement materials, the split strength, wearability and corrosion-resisting of PMCM are increased, its thermal contraction coefficient is decreased, the anti-permeability, frost-resisting and dry shrinkage of PMCC are increased, its thermal contraction coefficient is decreased greatly from(-20.1) to 0.0 ℃, it is decreased little from(-20.1) to 22.8 ℃. The performances of modified cement materials are increased greatly with the increase of polymer ratio.More>

2005, 5(4): 32-36.

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Evaluation method of differential scanning calorimetry for asphalt performance

CENG Fan-qi, HUANG Xiao-ming, LI Hai-jun

Abstract: In order to evaluate the high temperature performances of different asphalts, asphalt heat quantity was measured when the assembling state of original asphalt changed, and asphalt heat stabilities and change extents under different aging extents and paraffin wax contents were measured by DSC method. The result indicates that asphalt temperature stability is improved, asphalt temperature sensitivity is reduced after asphalt is modified; asphalt aging time is longer, asphalt heat stability is better; the lower asphalt paraffin wax content is, the better asphalt temperature sensitivity is. The testing results of DSC method and general high temperature index experiment are consistent, their relativity is good, DSC method is a better method to verify and evaluate asphalt high temperature performance.More>

2005, 5(4): 37-42.

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3-D FEM analysis of pavement crack at cut to fill location of subgrade

MIAO Ying-hao, HU Zhang-shun, WANG Bing-gang

Abstract: In order to prevent pavement cracking at cut to fill location of subgrade, the treatment mechanism and proper layout of geogrid were studied by 3-D finite element method(FEM), subgrade FEM models with various lengths of geogrid and various number of geogrid layers were built, a model without geogrid was also built for comparison, the vertical displacement, longitudinal stain and stress of pavement surface and geogrid stain and stress were analyzed. Geogrid in subgrade reduces the vertical displacement of pavement surface, scatters the concentrated tensile strain and stress at cut to fill location. The maximum geogrid stress and strain of all models are below 1 MPa and 0.3% respectively. For one layer case and the bottom geogrid for multilayer cases, geogrid stress and strain are decreased gradually from cut to fill side. In the other layers, geogrid stress and strain at cut side near cut to fill location are maximum. It is discovered that geogrid eliminate or postpone the pavement transverse cracking, for one layer case, geogrid should be longer in cut side than in the fill side, the bottom geogrid should be longer in cut side than in fill side, and the others should be laid symmetrically for multilayer cases.More>

2005, 5(4): 43-47.

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Calculation method of foundation bearing capacity based on division in loess area for highway engineering

SHI Gang, WANG Jin-guo, ZHI Xi-lan, LIU Yi-lin, ZHANG Jian-lin, XU Shi-qiang

Abstract: The foundation bearing capacity evaluation of highway engineering in loess area mainly relies on the evaluation standards of architecture, railway and other similar fields, they only provide a formula or bearing capacity table based on whole loess area, which can not meet the needs of highway engineering. Based on analyzing the data of actual plate loading test, the loess areas were divided into four sections according to their bearing capacities, the nonlinear regression relationship formulas were established between loess foundation bearing capacities and water content, liquid limit, void ratio. Applied result shows that the relative errors of the bearing capacities computed by the formulas are less than 10%, compared with other standard methods, the formulas are feasible. Meanwhile, the formulas are revised according to the width, relative distortion, rigidity and flexibility of subgrade.More>

2005, 5(4): 48-52.

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Nonlinear stability of simply supported tied-arch bridge with long span

XU Wen-ping, PEI Ming-hai, DAI Jie, XIA Ye-fei

Abstract: Nanhe bridge locates on Nanjing-Hangzhou highway. It is a simply supported, concrete filled steel tubular, tied-arch bridge with a span of 130 m.The bridge's 3-D finite element model of stability analysis was created by structural analysis program ANSYS based on considering its nonlinear stability influence factors. Its buckling modes were provided, its nonlinear solution method was discussed, the nonlinear stability calculation of the bridge was performed. The result shows that a plastic hinge is firstly developed at the arch springing, its stability collapse load is 3.5 times larger than the design load, which satisfies the requirement of the bridge stability.More>

2005, 5(4): 53-57.

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Fuzzy reliability evaluation of defective RC beam bridge

LU: Ying-zhao, HE Shuan-hai

Abstract: In order to improve the safe evaluation reliability of bridge, a fuzzy reliability evaluation model of defective RC beam bridge was put forward by fuzzy evaluation theory, analytical hierarchy process method and probability method. Through establishing fuzzy evaluation criterion, determining item level factors, index level factors and their weight coefficients, constructing probabilistic matrix of membership degree, the score of fuzzy reliability evaluation of defective RC beam bridge was calculated by weighted average method. The score was switched to fuzzy reliability index by the bounds of target reliability index and lowest reliability index. An existing multi-span RC beam bridge with 25 years was evaluated by the method. Its fuzzy reliability index is 3.769, which accords with the bridge condition. The evaluation result indicates that the method is feasible.More>

2005, 5(4): 58-62.

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Dynamic behaviors analysis of vehicle frame by BEM

FANG Ying-wu, ZHANG Yong-fang, ZHANG Guang-peng, HUANG Yu-mei, LU: Yan-jun, XU Hui

Abstract: For analyzing the dynamic properties of vehicle frame effectively in design, an area partition method based on boundary element method(BEM) was presented, the boundary equations of plate structure were established by using dynamic fundamental solutions of thin plate, the dynamic equations of vehicle frame were deduced. Computation result shows that the maximal relative error of BEM's values and experimental values for thin plate is 5.0%, the maximal error of FEM's values and BEM's values for vehicle frame is 5.9%.The dynamic characteristics of vehicle frame are analyzed fastly and efficiently, its modeling precision and calculation efficiency are improved greatly in design by BEM.More>

2005, 5(4): 63-66.

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Calculation method of brake NO_x emission from marine diesel engine

YIN Zi-bin, WU Gui-tao, SUN Pei-ting

Abstract: In order to improve the computation precision of exhaust gas flows, a new calculation method of brake NO_x emission from marine diesel engine was deduced by chemical reaction equations based on incomplete combustion and the principle of element quality balance, CO₂ gas was ignored, iterative calculation was avoided.For meeting the requirements and characteristics of on-board measurement of NO_x emission, approximate calculation methods based on the new method and simplified measurement were discussed. The calculation result of a example shows that the exhaust gas flows calculated by the new method are more accurate by 1.1%~1.5% than by carbon balance method, brake NO_x emission is more accurate by 0.3%~0.6%, and the error of weighted brake NO_x emission caused from ignoring CO and HC is less than 0.2%. The result proves the feasibility of simplified on-board measurement of NO_x emission because of ignoring CO and HC by handy gas analyzer.More>

2005, 5(4): 67-71.

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Fuzzy adaptive control for ship steering autopilot based on backstepping technique

ZHANG Song-tao, REN Guang

Abstract: In allusion to the nonlinear Norbin ship model, a new fuzzy adaptive control algorithm for ship steering autopilot based on backstepping technique and the approximation capability of the fuzzy system constructed by radial basis function(RBF) was put forward, all parameters of the fuzzy system were on-line tuned by Taylor linearization technique. A robust controller was employed to dispel the effect of the approximation error introduced by the fuzzy estimation system. The adaptation laws of the control system were derived based on Lyapunov function. Simulation result shows that the closed-loop control system of steering autopilot is asymptoticalry stable, the error of the output trajectory of ship model and a desired trajectory is zero. The proposed algorithm has better adaptive ability than traditional PID control algorithm.More>

2005, 5(4): 72-76.

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Course-keeping of inward-and-outward low speed ship

ZHANG Xian-ku, XIAO Wei-chu, GUO Chen

Abstract: In order to improve ship control performance, reduce ship energy consumption when ship navigates at low speed in inward-and-outward shallow water under strong wind and wave disturbance, third-order Nomoto model was chosen, ship speed and water depth were reflected into the changes of its parameters, a robust PID controller with adaptability based on closed-loop gain shaping algorithm was designed.The nonlinear mathematical model of ship motion with wind and wave disturbance was built and realized through programming its S-function.The designed PID controller was used to control the nonlinear mathematical model of ship motion in the conditions of various water depths, ship speeds and sea states.The simulation result shows that the course-tracking effect is satisfactory, the steady state error is zero, the rudder angle is reasonable, and the designed controller has good performance for the nonlinear mathematical model.More>

2005, 5(4): 77-81.

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Multi-leg seat inventory control model for airline revenue management

GAO Qiang, ZHU Jin-fu, CHEN Ke-jia

Abstract: In order to optimize multi-leg seat inventory control, improve airline revenue, multi-leg origin-derivation flows in terms of their fares were sorted, which were regarded as decision variables, the sum of every origin-derivation flow revenue expectation was set as object function, a stochastic program model for multi-leg seat inventory control was established, a genetic algorithm to solve the model was set up. The result using genetic algorithm to solve multi-leg seat inventory control problem shows that the computation maximum error of revenue is 0.34%, revenue computation values are stable, the model is feasible.More>

2005, 5(4): 82-85.

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Method of sector optimum partition based on controller workload

ZHANG Ming, HAN Song-chen

Abstract: In order to ensure flight security and increase airspace capability, in according to the balance rule of controller workload, a simulated annealing algorithm was adopted to solve sector optimum partition, which was based on the statistic method of controller workload and the mathematical model describing airspace topology structure. The new resolution satisfied the restriction of the three rules for airspace partition, they were preferential search, sector continuity and the minimum of sector number. The optimum result of Xiamen control airspace shows that the maximal workload difference among three sectors is 4.1 s, the value is smaller than 17.5 s, which indicates that the method is feasible.More>

2005, 5(4): 86-89.

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Conception of fourth generation port and its implementation methods

ZHEN Hong

Abstract: According to the generation theory of port development and supply chain management theory, the meaning, characters and implementing methods of the fourth generation port were studied, its definition was described, its functions were analyzed, the idea that the fourth generation port is flexible port was given. The four phases implementing the fourth generation port were suggested, including port business processes reengineering phase, JIT phase, lean phase and agile phase. The port flexibility is a strategic mode satisfying the fourth generation port development, which can help port to suit new economical environment brought by modern supply chain management. It is suggested that port operators must meet the customer demands of diverse service, create an agile port, so that port is put into modern supply chain management, and can enter the range of the fourth generation port.More>

2005, 5(4): 90-95.

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Multilevel-fuzziness-comprehensiveness evaluation model of waterway net planning

YU Jing, ZHANG Wei

Abstract: There are many subjective factors and their weights can not been reasonably decided in current evaluation model for waterway net planning. Based on analyzing various factors affecting waterway net planning, a kind of multiobject and multi-layer fuzzy model for comprehensive assessment was proposed. Combined with AHP, the weights of the assessment indices were determined. With statistical method of fuzziness, the membership grades of non-quantitative indices were determined. The benefit index, the neutral index and the cost index were applied to define the memberships of quantitative indices. The evaluation result for Suzhou waterway net planning indicates that the model can provide quantitative indices of waterway net actual case objectively and evaluate the waterway net planning accurately.More>

2005, 5(4): 96-100.

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Turn-based algorithm for Logit traffic assignment

REN Gang, WANG Wei

Abstract: To overcome the shortcomings in traditional network-expanding method for handling turn delays in traffic assignment, a turn-based algorithm for Logit traffic assignment was developed with a similar framework of Dial algorithm, which was based on the topological relationships between network element nodes, links and turns. According to the origin-to-link-type shortest path distances with turn delays, all links were processed, turn weights were computed forward, and link flows and turn flows were assigned backward by the algorithm. Computation result shows that the flow assignment of the algorithm is identical to Logit-based path flows and Dial's algorithm data, the algorithm directly computes link flow and turn flow patterns, which not only agrees with Logit route-choice probability, but also counts for the effect of turn delays on traffic assignment, and Dial algorithm is a special case of the algorithm when all turn delays vanish.More>

2005, 5(4): 101-105.

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Entropy models of inhabitant trip distributions and parameters calibration

YAO Rong-han, WANG Dian-hai

Abstract: In order to find some general models to describe all kinds of inhabitant trip distributions, according to the maximum information entropy theory and statistics, new models under the constraints of the means of origin moments were built, a parameters calibration method was put forward to ascertain the parameters of the models. They were validated by the inhabitant trip survey data in Changchun city. The trip modes of walk, bike, bus and car pass χ² tests with 95% confidence when their orders of the highest origin moments are 3, 4 and 5 respectively. The comparison of χ² values and inhabitant trip distributions curves shows that the orders are different when the best effects of all trip modes are gotten. The differences result from the inner characteristics of trip modes. Analyzing result indicates that the information entropy models can quantificationally describe the distribution principle of any trip mode, the parameters validation method is simple and effective.More>

2005, 5(4): 106-110.

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Models of passenger traffic sharing rates of regional transport corridor

ZHU Cong-kun, WANG Jie, FENG Huan-huan

Abstract: In order to solve the shortcoming of travel cost exact evaluation for passengers with Wardrop theory, uncertain programming theory was analyzed, the evaluations of different economy levels and different income leves passengers for transport modes were considered, the travel cost was expressed by mathematic expectation, three different computation models of passenger traffic sharing rates were set up, which were passenger equilibrium model, system optimization model and multi-object optimization model, a genetic algorithm based on stochastic simulation to calculate the models was put forward.Simulation result shows that the average error of computation values and measure values is 8.13%, which effectively indicates the uncertain of passenger choice transport modes.More>

2005, 5(4): 111-115.

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Driver perception model for road structure parameters

WEI Lang, ZHOU Wei-xin, LI Chun-ming, GAO Li-min, DAI Su-zhen

Abstract: In order to provide driver the basis experiment data and the evaluation subordination functions that are needed in speed-controlling model, the driver thinking evaluation procedure and safety perception to road structure and traffic environment were studied by fuzzy set principle and fuzzy statistic experiment analysis method. The road structure parameters of 226 highway sections were obtained from typical second-class highway sections of national roads, 1 785 groups of driver effective perception data of 131 highway sections were obtained from specialists' appraising experiment, the nonzero-sets of perceived comment collection based on 0.2-cut sets and the certain-sets based on 0.8-cut sets were set up, the simulation model and fuzzy comment subsets of driver safety perception to second-class highway structure and traffic environment were put forward.More>

2005, 5(4): 116-120.

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