2012 Vol. 12, No. 4

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Road and railway engineering
Cement concrete pavement design based on cumulative damage factor
CAI Liang-cai, ZHU Zhan-qing, WU Ai-hong, PAN Zheng-hua, WANG Wei-guo
Abstract: Based on the compositive fatigue equation of load fatigue stress and temperature fatigue stress, the coverage-to-pass ratios of single-axle-single-wheel load and single-axle-double-wheel load were calculated by adopting cumulative damage factor.A direct calculating method of total cumulative fatigue damage of pavement structure produced by multi-axle load and a new design method of cement concrete pavement were put forward by replacing design axle load with cumulative damage factor.The accuracy and application feasibility of calculating fatigue damage produced by multi-axle load were done through a design example with two types of traffic volumes.Analysis result indicates that the acting times of multi-axle load at all points on the cross section of highway are different, and the peak value of cumulative damage of each axle load may be not at the same location.The thicknesses of worst pavement places under the traffic volumes calculated by the design method based on cumulative damage factor are all 22 cm, which meets the design requirement, and the thicknesses of other places can reduce according to the cumulative damage curve.Thereby, it can avoid the differences and localizations of present specification design method of concrete pavement based on standard axle load and equivalent fatigue consumption principle.More>
2012, 12(4): 1-8. doi: 10.19818/j.cnki.1671-1637.2012.04.001
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Modified C-V model algorithm of crack extraction for bridge substructure
LI Gang, HE Shuan-hai, DU Kai, LIU Wei, DU Qin-wen
Abstract: The crack image segmentation of bridge substructure was studied by utilizing a modified C-V model.Crack clip, image filling and rotation transformation were applied for the precise extraction of crack width.The crack images of existing concrete bridge structure were taken in different illuminations, and test results were compared by using modified C-V model algorithm, adaptive threshold algorithm, morphology algorithm, C-V model and Canny algorithm.Analysis result indicates that the misclassification rate of modified C-V model algorithm is 3.02%, the operation time is 89 ms, and the values are minimum compared with other methods.Based on the comparative test on 1 000 crack images of bridge structure, the accuracy rate of crack detection is greater than 90.8%, and the mean error of crack width is less than 0.03 mm.So the modified algorithm can effectively improve detection accuracy rate, and reduce operation time.More>
2012, 12(4): 9-16. doi: 10.19818/j.cnki.1671-1637.2012.04.002
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Anti-slide model of cement concrete pavement based on surface texture
ZHAO Fang-ran, GONG Jin-hai, CHANG Yuan-yuan
Abstract: The frictional coefficients of several parts for cement concrete runway in an airport were tested by an anti-slide-test truck of T10 type.Different textural features were analyzed by photo analysis method and characteristic description method.The influence law of pavement superficial texture on frictional coefficient was discussed based on test results.A model of pavement anti-slide capacity was proposed based on texture characteristic parameters.According to the analysis of macro, rough and micro texture characteristic parameters, a pavement anti-slide frictional coefficient model was proposed based on texture characteristic.Analysis result shows that frictional coefficients vary from 0.40 to 0.42 when constructional depths are 0.6-0.7 cm on the similar texture characteristic roads.For the significant different texture characteristics, frictional coefficients are 0.43, 0.75 when constructional depths are 0.70, 0.78 cm respectively, so the influence of texture characteristic on pavement frictional coefficient can not be neglected.Based on the analysis of pavement texture characteristic parameters, the anti-slide model can be used to analyze the anti-slide capacity of old runway pavement quantitatively.More>
2012, 12(4): 17-24. doi: 10.19818/j.cnki.1671-1637.2012.04.003
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Study evolvement of high-speed railway tunnel aerodynamic effect in China
MA Wei-bin, ZHANG Qian-li, LIU Yan-qing
Abstract: The research methods of high-speed railway tunnel aerodynamic effect, such as field test, numerical simulation computation and indoor model test, were dissertated.The influence factors of tunnel aerodynamic effect were analyzed.The variation laws of transient pressures in train and tunnel and micro-pressure waves outside tunnel with different velocities, buffer structure setting conditions, the calculating method of additional air resistance in tunnel, the aerodynamic load requirements of tunnel subsidiary facilities, remote testing and control technology in large-scale tunnel, the accurate control method of train passing in tunnel were systematically studied when high-speed train set went through tunnel and rendezvoused in tunnel.Analysis result shows that the aerodynamic effect produced by high-speed train set through tunnel directly affects train security, passenger comfort and tunnel surrounding environment, it is the key technical problem that must be solved in the design of high-speed railway tunnel.Composite comfort and micro-pressure wave standards that are suitable for China are suggested, the researches on micro-pressure wave mitigative measures such as porous energy-absorbing materials, the buffer structure of tunnel hole, decompression shaft, cross-channel design should be carried out.More>
2012, 12(4): 25-32. doi: 10.19818/j.cnki.1671-1637.2012.04.004
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Transportation vehicle engineering
Identification method of wheel flat based on Hilbert-Huang transform
LI Zhong-ji, WEI Lai, DAI Huan-yun, CENG Jing, WANG Yi-jia
Abstract: Vehicle system dynamics model with 56 degrees of freedom and wheel flat model were set up to compute vehicle dynamic responses.HHT(Hilbert-Huang transform) spectrum characteristics of axle box vibration caused by wheel flat impact were studied by using HHT time-frequency analysis method.HHT spectrum characteristics of axle box vertical accelerations caused by wheel flat and out-of-round were compared.The influences of vehicle running speed and track excitation on HHT spectrum characteristics of axle box vibration caused by wheel flat impact were studied.Analysis result shows that HHT spectrum distribution of axle box acceleration is uniform for healthy wheel, the stripe interval of vertical bar distribution for flat wheel is inversely proportional with the speed, and transverse bar distribution for out-of-round wheel.Therefore, wheel flat can be identified according to HHT spectrum characteristics of axle box acceleration.The lowest distinguishable frequencies are 30, 50, 80 Hz for Beijing-Tianjian Line irregularity, existing line irregularity in China and American three-grade track irregularity respectively.The identification band is 40-100 Hz when the running speed is lower than 150 km·h-1, but it should be widened to 200 Hz when the speed is over 150 km·h-1.More>
2012, 12(4): 33-41. doi: 10.19818/j.cnki.1671-1637.2012.04.005
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H∞ robust control of multi-steering vehicle based on T-S fuzzy model
WANG Ji-hua, WEI Min-xiang, DU Yan-li, LI Yu-fang
Abstract: To solve the control problem of multi-steering vehicle under the influences of model nonlinearity and all sorts of disturbances, tire nonlinearity and external disturbances were analyzed, and the nonlinear model of multi-steering vehicle with two degrees of freedom was established and converted into local linear T-S fuzzy model based on Takagi-Sugeno(T-S) fuzzy theory.Combining parallel distributed compensation method(PDC) with H∞ robust control theory, the fuzzy PDC H∞ robust controller of steering system was designed and solved by using linear matrix inequality(LMI) and fuzzy logic control(FLC) tools.With the disturbances of sine wave and step signal, when vehicle velocity was 80 km·h-1, the simulation experiments of front wheel steering returnability and front wheel steering with angle step input were carried out.Based on the dynamic responses of side slip angle and yaw rate, all overshoots are 0, and all times to reach steady values are within 0.06 s.In former experiment, the steady values of side slip angle and yaw rate are all 0.In latter experiment, the values are 0 and 1.2(°)·s-1 respectively, and the steady gain of yaw rate is 0.24 [(°)·s-1]·(°)-1.Simulation result indicates that high-speed multi-steering vehicle with fuzzy PDC H∞ robust control can steer smoothly and rapidly, and the T-S fuzzy modeling method and the designing method of robust controller are effective to solve the problems of tire nonlinearity and external disturbances for multi-steering vehicle.More>
2012, 12(4): 42-49. doi: 10.19818/j.cnki.1671-1637.2012.04.006
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Automotive automatic transmission shift control based on layered coordination
XIA Guang, TANG Xi-wen, SUN Bao-qun, CHEN Wu-wei
Abstract: Automotive automatic transmission control strategy was divided into upper and bottom layer control parts, and its layered coordinated control was adopted.The bottom layer was the basic shift controls of optimal power and optimal economy, the upper decision-making layer was used to give the dominant analysis and priority settings for the identifiable informations of driving intention, vehicle condition and road environment, vechicle control objective with optimal performance at present state was given, and the amendment and adjustment of basic shift control strategy for bottom layer were made.Analysis result indicates that compared with independent control, the shift times of vehicles based on layered coordinated control strategy in climbing ramp and bend conditions reduce by 4 times and 2 times respectively, shift reduces promptly when gearbox oil temperature rises, and shift is higher when vehicle starts on low-adhesion coefficient road.The layered coordinated control strategy can reduce shift jump frequency and the wear and tear of shifting part, improve vehicle passing ability, ride comfort and safety.More>
2012, 12(4): 50-58. doi: 10.19818/j.cnki.1671-1637.2012.04.007
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Transportation planning and management
Comprehensive passenger hub layout model of combined selection for capacity limitation and transportation mode
HU Hui, CHENG Ling, XUAN Deng-dian, HU Da-wei, ZHAO Li-ping
Abstract: The traditional optimization model of comprehensive passenger hub layout was analyzed, and the constraints of transportation mode and transfer capability were considered simultaneously. The improved optimization model of comprehensive passenger hub layout was proposed, and the improved genetic algorithm was introduced to solve the model. LINGO software was used to test the effectiveness, Solomon standard test data with 8 and 50 nodes were calculated respectively, and the improved model was compared with the classical algorithm. Calculation result shows that while calculating Solomon standard test data with 8 nodes, the average running time is 5 043 s and the optimal cost is 1 952 418 yuan by using LINGO software, the average running time is 62 s and the optimal cost is 1 955 900 yuan by using genetic algorithm and MATLAB software. While calculating Solomon standard test data with 50 nodes, the average running time is 574 s and the optimal cost is 8 500 600 yuan by using genetic algorithm and MATLAB software. While calculating AP data set with 25 nodes and hub node number is 3, the average running time is 612 s and the optimal cost is 155 148 yuan, the optimal cost decreases 108 yuancompared with the classical algorithm. So the improved model is effective. 6 tabs, 6 figs, 20 refs.More>
2012, 12(4): 59-66. doi: 10.19818/j.cnki.1671-1637.2012.04.008
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Design model of traffic network based on stochastic supply and stochastic demand
YU Xin-xin, LU Hua-pu, LI Yang-yang, SUN Xu, BIAN Zhang-zhi
Abstract: In order to improve the traditional design method of traffic network based on definitive supply and definitive demand, the hi-level programming theory and traffic assignment theory were used, and the design model of traffic network based on stochastic supply and stochastic demand was set up. The Monte Carlo simulation, genetic algorithm and traffic assignment algorithm were applied in model solving process, and Nguyen-Dupuis traffic network was used to solve the model. Calculation result indicates that when the OD demand increases, the total travel time increases. When the construction budget increases, the total travel time decreases. When both supply and demand are uncertain, the effect of increasing construction budget on decreasing total travel time is more significant. Under different conditions, the maximum value of total travel time is 1.69 ×105 h, and the minimum value is 8.89 ×104 h. When the average value of OD demand is 350 veh·h-1 and the construction budget increases from 10 million yuan to 15 million yuan, the total travel time decreases by 3.47% under certain supply. The uncertain degrees of stochastic supply and stochastic demand have important influence on the design method of trafficnetwork. 9 tabs, 17 figs, 19 refs.More>
2012, 12(4): 67-74. doi: 10.19818/j.cnki.1671-1637.2012.04.009
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Calculation model of maximum travel distance on urban road
LONG Xue-qin, GUAN Hong-zhi, QIN Huan-mei
Abstract: In order to reflect the influence of traffic accident delay on route choice for traveler reasonably, traffic accident delay model under random state was put out.The uncertain factors of traffic accident such as randomness, duration and road capacity were introduced into traffic assignment model, and the route choice model was modified.The maximum preponderant travel range of each grade road was analyzed.According to the modified route choice model, successive traffic assignment method was adopted.The turnovers and travel distances of all grade roads were got, and the travel distances were compared with the travel distances while traffic accident delay was not considered.Analysis result shows that while traffic accident delay is considered, the maximum travel distances of brunch, secondary primary road, main road and expressway are 2.000, 2.946, 4.054 and 5.963 km respectively.While traffic accident delay is not considered, the maximum distances of those roads are 2.000, 3.000, 6.000 and 10.000 km respectively.Traffic accident delay is the significant factor for traveler route choice.While traffic accident delay is considered, the maximum travel distances of higher grade roads decrease.Compared with the conventional route choice models, the proposed model is better.More>
2012, 12(4): 75-82. doi: 10.19818/j.cnki.1671-1637.2012.04.010
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Quick approaching assistant decision system of distress target on sea surface
FAN Zhong-zhou, LIU Da-gang, LI Kang, LUO Hong-hong, WU Zhao-lin
Abstract: Under heavy weather condition, in order to make rescue ship approach distress target and implement assistance while the self-security of rescue ship could be guaranteed, the method of expert consult survey was used, and the stall situations, navigation leeways and risk grade membership degrees of brunt rescue ships in Beihai Rescue Bureau were obtained.Based on fuzzy mathematics and risk analysis theory, the risk evaluation model of rescue ship was set up, the functional requirements such as the integrated display of heavy weather information and the optimal route platform of rescue ship based on electronic chart were carried out, the evaluation process of route risk was optimized, and the quick approaching assistant decision system of distress target on sea surface under heavy weather condition was designed.Simulation result indicates that though BHJ196 is the nearest rescue ship to distress target, the route risk is too large, and the membership degree of Ⅲ-grade risk is 1.0.While approaching distress target by No.2 route, BHJ108 will encounter 8-grade crosswind, the membership degree of Ⅲ-grade risk is 0.5, stall situation is significant, and navigation time is too large.The safety of No.1 route for BHJ113 is better, and navigation time is the least, so the No.1 route of BHJ113 is the optimal route.The simulation result is consistent with the actual result, so the proposed system is effective.More>
2012, 12(4): 83-92. doi: 10.19818/j.cnki.1671-1637.2012.04.011
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Optimization model of dry bulk feright in Yangtze River based on river-sea transportation mode and investment constraint
RUAN Ning, LI Xiang, LIU Zhi-xue
Abstract: The concepts of river-sea transportation mode and investment constraint were introduced, the existed transportation network of dry bulk freight in Yangtze River was optimized, and the characteristics of river-sea transportation mode and river-sea combined transportation mode were compared.According to the characteristic of mature market for inland shipping and the management feature of rolling planning for shipping enterprise in China, the minimum operation cost and the minimum ship investment cost were taken as objective functions, and the model that integrated transportation mode selection, ship assignment and ship type update was set up.The time dimension of the model was simplified, the Lagrangian relaxation algorithm based on knapsack problem was designed, and the data of group A were used to solve the model.Analysis result shows that while the total shipping cost of current mode is taken as a reference point, the total shipping cost can decrease by about 2% after using river-sea combined transportation mode.After using river-sea transportation mode, the maximum descent range is more than 8%, but the financial risk will increase.While the fund cost rate is 7% and the investment constraint is not considered, cost-reduction effect increases by 16.2%, but net investment budget will raise by 60.1%.From the configuration of optimal route, the river-sea transportation mode and river-sea combined transportation mode must be used together on different routes.More>
2012, 12(4): 93-99. doi: 10.19818/j.cnki.1671-1637.2012.04.012
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Traffic information engineering and control
APG-TR algorithm of moving vehicle detection
CHEN Tao, TAN Hua-chun, FENG Guang-dong, WANG Zhen-yu, WEI Lang
Abstract: In order to improve the accuracy of moving vehicle detection in intelligent transportation system, an accelerated proximal gradient-tensor recovery(APG-TR) algorithm was proposed based on tensor recovery.The traffic video image data were characterized by using tensor in the algorithm, which maintained the high-dimensional structure characteristic of video image.The lower rank part and sparse part in the tensor were effectively reconstructed by tensor recovery, and moving target vehicle and traffic background were separated, therefore the internal properties were easily extracted.The algorithm was tested by using 106 video images collected by traffic monitoring system.Test result shows that the average detection accuracies are 91.4% in fine days, 86.4% and 85.2% under rain and fog conditions respectively, which are more stable and accurate compared with the frame differential method.APG-TR algorithm is proved to have good convergence speed and robust, and has abroad application in the field of intelligent transportation.More>
2012, 12(4): 100-106. doi: 10.19818/j.cnki.1671-1637.2012.04.013
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Detecting and tracking method of moving vehicle
LOU Lu, ZHAO Ling, GENG Tao
Abstract: In order to improve the comprehensive management ability of intelligent transportation systems in cities, a detecting and tracking method of moving vehicle was presented by using video analysis. Considering the pavement environment of urban transport artery and the difference between moving object and the statistical characteristics for road background, an adaptive background updating algorithm was realized based on Bayesian probability criterion, from which foreground image was extracted. Motion detection and real-time tracking were realized for target vehicle in video sequence based on Kalman filter. The traffic flow video collected from a certain urban transport artery of Chongqing was detected by using the proposed method. Experimental result indicates that the video with normal resolution can be processed in time by using the method, and the average detecting accuracy is 94 %, so the proposed method has good real-time performance and robustness, and meets the requirement of real- time detecting and tracking vehicles in urban traffic arteries. 2 tabs, 5 figs, 15 refs.More>
2012, 12(4): 107-113. doi: 10.19818/j.cnki.1671-1637.2012.04.014
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Short-term traffic flow prediction model
FAN Na, ZHAO Xiang-mo, DAI Ming, AN Yi-sheng
Abstract: A new hybrid prediction model including two single models of nonparametric regression model and BP neural network model was proposed according to the periodicity and randomness properties of short-term traffic flow.Relevant historical traffic flow data were used in nonparametric regression model to make the prediction result abtained from the databases matching proceeding fully illustrate the cyclical stability of traffic flow.Three-tier BP neural network model was used to reflect the dynamic and nonlinear characters of traffic flow.Fuzzy control algorithm was adopted to get the weight coefficient of each model.New mixed model was constituted by the two single models according to different weight coefficients.The prediction effect of hybrid prediction model was verified by the traffic flow data in 30 d from a certain section in Xi'an.Experimental result indicates that the average relative error of mixed model is 1.26%, and its maximum relative error is 3.53%, so the prediction accuracy of mixed model is obviously higher than two single models, and can accurately reflect the real situation of traffic flow.More>
2012, 12(4): 114-119. doi: 10.19818/j.cnki.1671-1637.2012.04.015
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Improvement method of WSNs for real-time monitoring
LEI Tao, WANG Song, HUI Fei, ZHAO Xiang-mo
Abstract: A WSNs-based real-time monitoring system was built in view of the application in hazardous materials transportation monitoring.MAC layer protocol and physical layer transmission time sequence of the monitoring system were improved and optimized.Priority supported GDCF algorithm was introduced after improving the original BEB algorithm of MAC layer.Effectiveness analysis was made for the RTS/CTS mechanism of MAC layer.Sleep mode was introduced for energy saving.Time sequence was optimized to reduce data transmission time and collision probability in physical layer data transmission.Practical test was made by IRIS node platform installing on an engineering automobile.Test result shows that the drop rate using improved backoff algorithm has no significant change with the increase of network node number.The drop rate without RTS/CTS mechanism reduces from the original about 20% to less than 6% when the giving sampling interval time is 50 ms, and 95% energy is saved in every working period.Design goal is achieved in improved time sequence of wireless data transmission, and the performance requirements in real-time monitoring system of WSNs are satisfied in practical application.More>
2012, 12(4): 120-126. doi: 10.19818/j.cnki.1671-1637.2012.04.016
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