2012 Vol. 12, No. 5

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Black and white interlaminar instability failure of asphalt overlay on old cement slab
LIU Kai, WANG Fang, KANG Xin
Abstract: In order to study the two kinds of instability failures between asphalt overlay and old cement slab such as black and white interlaminar horizontal shear slippage and interfacial bonding instability, the influence rules of vehicle speed, road adhesion coefficient, vertical load, interlaminar contact coefficient, loading rate, temperature and the spraying amount of viscous oil on interlaminar extreme stress and strain, shear strength and pull-out strength were revealed through the elastic theoretical calculation of composite structure, MATLAB programming, interlaminar shear test and pull-out test.The function relationships among interlaminar shear strength and normal stress, shear rate, temperature, and among pull-out strength and pull-out rate, temperature, the spraying amount of viscous oil were established respectively.Analysis result shows that the descending order of pull-out failure interface occurrence probabilities at 15 ℃ is cement slab surface, tack coat, asphalt membrane, the descending order at 45 ℃ is tack coat, cement slab surface, asphalt membrane, and average interlaminar bonding strength increases with the descending of above order.In order to reduce interlaminar instability failure, vehicle speed should be increased appropriately, vehicle axle load should be controlled, the clean and rough surface conditions of old cement slab should be kept, the spraying amount of viscous oil should be chosen appropriately, liquid petroleum asphalt is 0.20-0.40 L·m-2, and emulsified asphalt is 0.48-0.60 L·m-2.The average pull-out strength of core sample and interface failure position are recommended as distinguishinging bases for the construction quality of asphalt overlay.More>
2012, 12(5): 1-12. doi: 10.19818/j.cnki.1671-1637.2012.05.001
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Fuzzy control of fire smoke in single highway tunnel with subtended traffic
WANG Ya-qiong, DENG Min, HU Yan-jie, HU Jin-ping, XIE Yong-li
Abstract: In order to eliminate the influence of fire smoke on people in single highway tunnel with subtended traffic, a fire numerical calculation model was established.The theory of fuzzy control was introduced into the control of fire smoke, and the reciprocating motion of smoke in the area of 200 m between two groups of jet fans in the tunnel was simulated.By changing the wind velocities and directions of jet fans in tunnel, the distribution and influence law of smoke within the control area were studied when smoke diffusion times were 180 and 360 s, and wind velocities were 1.0 and 1.5 m·s-1.Calculation result shows that after jet fans on both sides of fire source are started respectively, the smoke is basically controlled at the positions of 50-80 m on both sides of fire source, and its motion belongs to small amplitude motion when the start interval of jet fans is 30 s and wind velocity is 1.0 m·s-1.When the interval is 60 s and the speed is 1.5 m·s-1, the smoke is basically controlled at the positions of 80-100 m, and its motion is large amplitude motion.The small amplitude motion is superior to large amplitude motion.More>
2012, 12(5): 13-21. doi: 10.19818/j.cnki.1671-1637.2012.05.002
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Coupling vibration of wind-vehiche-bridge system for long-span steel truss cable-stayed bridge
LI Yong-le, LI Xin, XIANG Huo-yue, LIAO Hai-li
Abstract: A long-span road-rail steel truss cable-stayed bridge was taken as an engineering example, the aerodynamic coefficients of vehicle and bridge at different states were measured through wind tunnel test with the section models of vehicle and bridge. Wind-vehicle-bridge system was simulated at different wind speeds, vehicle speeds and vehicle load states by using the self-developed software BANSYS. The influences of vehicle position and two trains passing each other on the system were discussed. Computation result shows that wheel load reduction rate exceeds safety limit value when vehicle speed is up to 100 km·h-1 and wind speed is 25 m·s-1. When vehicle speed is up to 120 km·h-1, vehicle vertical acceleration exceeds comfortable limit value. When wind speed is higher, the wheel load reduction rate of vehicle running on windward side is the control factor for wind-vehicle-bridge system. The unloaded vehicle response is larger than overcrowded vehicle. Due to the wind shielding effect for windward side vehicle, transverse accelerations change suddenly at the beginning and ending of the process for two trains passing each other.More>
2012, 12(5): 22-27. doi: 10.19818/j.cnki.1671-1637.2012.05.003
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Simulation and monitoring of high-speed railway tied-arch bridge construction with arch first and beam late method
REN Wen-feng, WANG Xing-hua, TU Peng
Abstract: The tied-arch bridge of Qingyang Harbour for Beijing-Shanghai High-Speed Railway was taken as research object, finite element simulation analysis and field monitoring were used, the stresses and strains of arch ribs and suspenders for high-speed railway tied-arch bridge with arch first and beam late construction method were calculated under different construction processes, and the change laws and control essentials of arch rib and suspender cable in construction process were analyzed. Calculation result shows that the maximal resilience deformation of arch rib is 37 mm by using finite element simulation, and the maximal compressive stress appears in the time between the closure of tied beams and the removing of temporary consolidation. The calculated elevations of arch rib points are identical with actual measurement values, and all the differences are less than 10 mm. The compressive stresses in main arch show a uniform distribution and are less than 80 MPa. So the construction method of arch rib integral hoisting and arch first and beam late is feasible.More>
2012, 12(5): 28-36. doi: 10.19818/j.cnki.1671-1637.2012.05.004
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Calculation method of critical buckling stress for stiffened plate with closed ribs
ZHANG Qian, DI Jin, ZHOU Xu-hong
Abstract: A calculation method of critical buckling stress for stiffened plate with closed ribs was proposed by using energy method under unidirectional uniform pressure and simply supported on four sides. The influence of torsional rigidity of stiffened ribs was considered, the whole flexural rigidity of mother board and stiffened ribs was calculated according to the centroid of actual section. The stiffened plates with closed trapezoidal ribs in the steel box girder of Suzhou-Nantong Bridge were taken as example, the critical buckling stresses calculated by Timoshenko method, Ichiro Konishi method, shell finite element method and the proposed energy method were compared. Analysis result shows that when the length-width ratio β of stiffened plate is less than 1, the ratio λ values of critical buckling stress to steel yield strength calculated by Timoshenko method and Ichiro Konishi method are greater than the calculation value of energy method. When β is between 1 to 6, the λ values calculated by Timoshenko method and Ichiro Konishi method are less than the calculation value of energy method. When β is between 3 to 6, the calculation value of energy method is most approaching with the result of finite element analysis, their difference is between 9% to 25%. So the proposed energy method is feasible to analyze the elastic stabilities of top and bottom plates for orthotropic steel box girder.More>
2012, 12(5): 37-42. doi: 10.19818/j.cnki.1671-1637.2012.05.005
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Influence of train tail exhaust device on longitudinal force of train
WEI Wei, HU Yang
Abstract: Based on airflow theory and multi-rigid dynamics, a train combined simulation model of longitudinal dynamics and air brake system with train tail exhaust device was established, the transient numerical solution of airflow in the brake system was calculated, the performance of brake system was obtained, and train longitudinal dynamics was simulated synchronously. Simulation result shows that for 20 000 t train, tail exhaust device can reduce the maximum coupler force by 54% at full application brake, which is more obvious. The greater the pressure reduction of brake pipe is, the smaller the coupler force is. Now the fixed pressure reduction in tail exhaust device is 50 kPa, and it should be modified according to the common pressure reduction. The exhaust speed and lag time of tail exhaust device have little effect on train coupler force. When tail exhaust device is replaced with locomotive, the coupler force reduces under full service application, the greater the reduction of service application is, the greater the difference between locomotive and tail exhaust device is. When the reduction is 50 kPa, there is no difference between locomotive and tail exhaust device.More>
2012, 12(5): 43-49. doi: 10.19818/j.cnki.1671-1637.2012.05.006
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Influence of equipment under car on carbody vibration
WU Hui-chao, WU Ping-bo, CENG Jing, WU Na, DAN Yong-lin
Abstract: In order to consider the elastic vibration of carbody, the vertical coupling vibration model of carbody and equipment was established, the influence of rigid suspension and flexible suspension on the amplitude-frequency characteristic of carbody was studied, in which carbody was modeled as an Euler-Bernoulli beam. The 3D rigid-flexible coupling dynamics model of high-speed EMU was set up based on the modal superposition method and considering carbody elastic vibration and equipment, the influence of equipment's suspension types, partial loads and suspension parameters on carbody vibration was andyzed. The numerical analysis result of Euler-Bernoulli beam model shows that reasonable elastic suspension design based on the principle of dynamic vibration absorber can effectively suppress the elastic vibration of carbody and improve the vertical bend frequency of carbody. The simulation result of 3D rigid-flexible coupling dynamics model shows that the higher the speed is, the more obvious the advantage of elastic suspension is, equipment's lateral partial load affects the lateral riding index of carbody, and the longitudinal partial load mainly affects the vertical riding index. When the flexible suspension frequency of equipment is close to carbody bend frequency, the minimum vibration of carbody occurs. But as the suspension frequency of equipment is less than carbody bend frequency, rising damping can suppress carbody vibration to some extent.More>
2012, 12(5): 50-56. doi: 10.19818/j.cnki.1671-1637.2012.05.007
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Accumulator parameter matching of active suspension without external energy supply
ZHOU Yu-cai, CHEN Shi-an, WANG Yong-gang, WANG Dong, HE Ren, LIU Hong-guang
Abstract: In order to reasonably match the pre-charge pressure, maximum working pressure and volume of accumulator for active suspension without external energy supply based on LQG(linear quadratic Gaussian) control, twice standard deviation of ideal control force was proposed as the maximum force output of active suspension to meet 95.4% of work demand, and the parameters of reclaiming energy/active cylinder were taken into account to ascertain the ideal working pressure of accumulator. To make the pressure fluctuation in accumulator less than 5%, the pre-charge pressure and maximum working pressure of accumulator were matched. The energy flow equations between active suspension and accumulator were deduced. Under 2 kW load, the varying volume's dynamic simulation of accumulator was carried out. Computation result shows that the ideal working pressure of accumulator is 23.008 MPa, and the quadratic performance index of the suspension increases 5.21% compared with the ideal state. Accumulator's pre-charge pressure, maximum working pressure and volume are 11.108 MPa, 23.583 MPa and 2.5 L respectively, and the maximum pressure fluctuation in accumulator is 1.03% when the active suspension without external energy supply based on LQG control works steadily. So the demand with low manufacture cost, good suspension performance and high energy reclaiming efficiency for the active suspension is achieved.More>
2012, 12(5): 57-63. doi: 10.19818/j.cnki.1671-1637.2012.05.008
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Analysis method of urban road network structure based on complex network
ZHANG Wei-hua, YANG Bo, CHEN Jun-jie
Abstract: Based on urban road network, the feasibility and effectiveness of complex network theory application were analyzed.By using Dijkstra shortest path algorithm and Space L method, the initial topology network was built, and the characteristic index models of the degree of node, the degree of edge and the road impedance of node were set up.Under the premise of reflecting the reality of road network function, the initial topology network was optimized, and empirical analysis was carried out by using road traffic data in a central urban area.Analysis result shows that in the initial topology network, the average node degree is 2.850 0 and the standard deviation of node degree is 0.670 8.The average road impedance of node is 84.680 0 s and the standard deviation is 11.768 8 s.While in the optimal topology network, the average node degree is 38.750 0 and the standard deviation of node degree is 24.683 0.The average road impedance of nodes is 91.780 0 s and the standard deviation is 18.862 8 s.The average degree of east-west road section is 42.00, the average degree of north-south road section is 29.86, the average degree of internal section is 55.00, and the average degree of external road section is 28.33.In the optimal topology network, when the node with large degree is not stable, the road impedance of shortest path will increase in non-crowded state, and the road network will be paralyzed in crowded state.The node with higher degree is accord with the importance degree of intersection in real road network, and the difference of importance degree for intersection can be more reflected.More>
2012, 12(5): 64-71. doi: 10.19818/j.cnki.1671-1637.2012.05.009
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Optimization design model of one-way traffic for road network
YANG Zhong-zhen, WU Shan-hua, LUO Hong-hong, JIAO Xin-long
Abstract: In order to improve the capacity and service level of road network, a bi-level programming model for one-way traffic was put out. The objective functions of upper-level model were the minimum total trip time, the shortest bypassing distance and the least conflict point number, and the upper-level model was used to solve the optimized scheme of one-way traffic. The lower-level model was user equilibrium traffic assignment model, and was used to calculate the traffic flow characteristic of section in road network from the upper-level model. The methods such as road section combination and feasible solution judgment were put out to decrease the decision variables and the solution space, the multi-objective genetic algorithm was designed to find the solutions, and example analysis was carried out by the data in Weihai City. Analysis result indicates that after the implementation of one-way traffic, the average ratio of vehicle flow to road capacity decreases from 0.516 1 to 0.487 1, and the variance of average ratio reduces from 0.418 9 to 0.379 1. The average trip time of vehicle decreases from 27.1 min to 25.4 min, while the average circumambulated time caused by one-way traffic is only 0.61 min. It is clear that the proposed model can be used in the scheme design of one-way traffic in a medium-sized city.More>
2012, 12(5): 72-78. doi: 10.19818/j.cnki.1671-1637.2012.05.010
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Bi-level programming model of decision optimization of reconstruction and expansion for highway network
GUI Bin, ZHOU Wei, WANG Jian-hua, ZHOU Li, WANG Xia-sen
Abstract: Aiming at the reconstruction and expansion problems of highway network, the factors such as technique, fund, environmental protection and operation efficiency were considered during the decision optimization process. The minimum traffuc volume of highway network system was taken as the objective function of upper-level model, the minimum trip time was taken as the objective function of lower-level model, the service level of road section, land occupancy status and construction investment were taken as constraint conditions, and a bi-level programming model of decision optimization of reconstruction and expansion for highway network was set up. Genetic algorithm was used to solve the model, and empirical analysis was carried out by using the example data of Northern Jiqing Highway. Calculation result shows that the expansion optimization indexes of Jinan-Zibo section, Zibo-Qingzhou section and Qingzhou-Weifang section for Northern Jiqing Highway are 2.15, 4.09 and 3.54 respectively, while the newly-built optimization indexes of the road sections are 1.87, 3.09 and 2.73 respectively. The expansion optimization index is higher than the newly-built optimization index for each road section, which is close to actual experience, so the model is effective.More>
2012, 12(5): 79-84. doi: 10.19818/j.cnki.1671-1637.2012.05.011
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Slot switching model of airlines under cooperative game
YAN Jun, WU Tong-shui, GAO Qiang, ZHU Jin-fu
Abstract: Aiming at the ground holding problem under the operation mode of flight bank, slot switching strategy was proposed. The minimum passenger delays of all airlines involved in slot switching were taken as objective functions, the Pareto improved solution was taken as constraint condition, and the slot switching model between two airlines was established by using cooperative game theory. The model was decomposed into slot assignment model and slot combination model. By using slot assignment model, the optimal assignment scheme and objective function value under determined slot condition were obtained. By using slot combination model, the optimal slot allocation schemes of two airlines were obtained. Computation result shows that without slot switching, the total passenger delays of airlines 1 and 2 are 238 955, 145 170 min respectively. After switching six slots between two airlines, the total passenger delays of airlines 1 and 2 are 232 945, 142 130 min respectively, and reduce by 2.5% and 2.1% respectively. When flight information is complete, slot switching can make airlines get optimal Pareto improved solutions. When flight information is imcomplete, airlines can obtain better slot switching schemes by using bargaining method.More>
2012, 12(5): 85-90. doi: 10.19818/j.cnki.1671-1637.2012.05.012
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Influence of driving experience on gazing behavior characteristic for car driver
GUO Ying-shi, MA Yong, FU Rui, MENG Ni, YUAN Wei
Abstract: In real vehicle driving test, the eye movement parameters and gazing behavior characteristics of 20 drivers were tested by using EyeLink Ⅱ eye movement tracking device on urban road and highway respectively. The participant drivers were divided into experienced driver group and novice driver group. By decompositing the traffic scene videos in the actual driving process frame by frame, and the real fixation targets of the drivers were determined by combining the eye movement data of drivers. The characteristics of fixation area and fixation target for experienced drivers and novice drivers were compared, the influences of driving experiences on the gazing behavior characteristics for two groups were studied, and the reason induced the difference between the two groups was analyzed. Research result indicates that driving experience has significant influence on gazing behavior characteristic. When driving on urban road, experienced drivers pay 18% more attention to near objects, and 4.7 times more attention to in-vehicle rear view mirror than novice drivers. On highway, the fixation frequency percentage on distant area for novice drivers is only 41% of experienced drivers, and the percentage on in-vehicle area is 2.1 times than experienced drivers. The average fixation frequency of drivers on right side area is about 2.5 times than on left side area, while it is 4 times for experienced drivers and 1.5 times for novice drivers respectively. Both the strategy and effectiveness of visual information processing for novice drivers are poorer than experienced drivers.More>
2012, 12(5): 91-99. doi: 10.19818/j.cnki.1671-1637.2012.05.013
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Detection method of queuing vehicles on urban road
SHI Zhong-ke, QIAO Yu
Abstract: Aiming at the detection problem of queuing vehicles under the condition of urban road, a synthesis method based on edge information and local texture feature was put out. According to the characteristics of traffic enviroment, the performances of five different edge detection methods were compared, Canny algorithm was used to extract the edge information, and the improved LBP method was used to extract texture feature. The comprehensive detection result of vehicle was obtained, and the traffic parameters such as vehicle queuing length and lane occupancy rate were extracted. The proposed method, Gaussian mixture model and frame difference method were used to treat the video images of different scenes such as expressway, intersection, rainy weather, illumination mutation, heavy snowy weather and dense fog weather, and the quantitative evaluation of detection performance was carried out through ROC curve. Analysis result shows that under the scenes of expressway and heavy snowy weather, the detection performances of three methods are almost same, the best detection rates are close to 90.0% and 60.0% respectively, and false alarm rates are no more than 5.0% and 10.0% respectively. Under the scene of intersection, the best detection rates of three methods are 77.1%, 31.5% and 13.6% respectively, false alarm rates are 16.5%, 3.2% and 19.0% respectively. Under the scene of rainy weather, the best detection rates of three methods are 65.2%, 3.0% and 62.4%, false alarm rates are 10.5%, 5.0% and 56.5% respectively. Under the scene of illumination mutation, the best detection rates of three methods are 62.0%, 18.9% and 39.7%, false alarm rates are 10.8%, 55.1% and 36.0% respectively. Under the scene of dense fog weather, when visibility is lower, the detection rates and false alarm rates of three methods are close to zero.More>
2012, 12(5): 100-109. doi: 10.19818/j.cnki.1671-1637.2012.05.014
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Real-time pedestrian detecting and warning system
CHENG Ru-zhong, ZHAO Yong, WANG Zhi-zhong, XU Jia-yao, WANG Xin-an
Abstract: A real-time pedestrian detecting and warning system(PDWS) based on the features of pedestrian side was proposed to solve the problem of pedestrian protection in serious traffic accidents. The system consisted of two parts, detecting module and warning module. The feature extraction and detection pedestrian were completed by using side pedestrian sample dataset in detecting module, Haar and HOG features together with AdaBoost and SVM classifiers were applied to complete the feature extraction and detection. Window-dividing method and operator context scanning(OCS) method were used to improve the detecting efficiency, and a result with both high detection rate and low false alarm rate was obtained. The velocity and angular velocity of automobile together with the distance of detected pedestrian were merged in warning module, so the system could judge the collision risk for the pedestrian in the front. The system and the algorithms were tested toward the pedestrian crossing street with a complex urban envirnment in real vehicle. Test result shows that for the images with 704 Pixel×576 Pixel, the frame rate is about 13-18 frame·s-1, the detecting rate is above 85%, the false detecting rate is below 1%, and the warning response time is less than 1 s. The result meets the requirements of on-board active safety system both in accuracy and real-time use.More>
2012, 12(5): 110-118. doi: 10.19818/j.cnki.1671-1637.2012.05.015
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Variable speed-limit control before expressway mainline toll station
PU Yun, HU Lu, JIANG Yang-sheng, ZHU Juan-xiu, PENG Bo
Abstract: An optimization model of variable speed-limit control with the object of the least accident rate and the limitations of cost and speed was set up, in which the number of variable message signs and corresponding variable limit speeds were determined. The distances between variable message signs were computed by using the traffic wave model, and the optimization model was verified by using the simulation software Vissim. For different traffic flows, variable speed-limit control and static speed-limit control were simulated on the expressway with two-lanes and six toll windows in single direction. Analysis result shows that when 4 variable message signs with setting separation distances of 1 293, 2 695 and 4 056 m apart are installed before the queuing square of expressway mainline toll station, the minimum relative error between simulation result and calculated values of traffic wave model is 3.9%, and the maximum is 9.5%. Compared with static speed-limit control, passing vehicle number in variable speed-limit control rises by 51.82%, average travel time and queue length decrease by 15.81% and 18.98% respectively, which proves that the model is reasonable.More>
2012, 12(5): 119-126. doi: 10.19818/j.cnki.1671-1637.2012.05.016
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