交通运输工程学报

Image recognition method of asphalt-aggregate ratio for asphalt mixture

CHA Xu-dong, LIU Lin-hui, BAI Lu, HAN Xiao-liang

Abstract: In order to verify the asphalt-aggregate ratio of asphalt mixture in a rapid and convenient way, the common asphalt mixture AC-13C was selected to shape standard Marshall specimens at different asphalt-aggregate ratios with compaction method. The specimens were cut horizontally, the digital photos of cross sections for asphalt mixture were photographed with a digital camera, and asphalt gray features were extracted by using image processing method. Analysis result shows that there is a typical double-peak distribution feature for the gray frequency distribution curve in the cross section image of asphalt mixture. The weighted probability density function of double-normal distribution is applied to fit the left peak semi-branch curve of gray frequency distribution, and the extracted asphalt gray features are obvious. There is a significant linear correlation between the obtained recognition asphalt contents and the practical asphalt-aggregate ratios, and the determination coefficient is more than 0.99. The absolute errors between the recognition asphalt-aggregate ratios of image recognition method and the practical asphalt-aggregate ratios are generally within ±0.1%. So the application of image processing technology is feasible to recognize the asphalt-aggregate ratio of asphalt mixture.More>

2013, 13(1): 1-6. doi: 10.19818/j.cnki.1671-1637.2013.01.001

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Gradation fractal characteristic and mechanical indexes of super large stone asphalt mixture

JIANG Xiao-xia, TAN Run-pu, GAO Wen-yang, SHA Ai-min, CHANG Ming-feng

Abstract: In order to quantificationally evaluate the gradation characteristic of super large stone asphalt mixture(SLSM), a method was put forward to calculate the aggregate mass fractal distribution function of SLSM based on fractal theory. The values of mass fractal dimension were obtained for SLSM-40 with different gradations, and a relational model between aggregate mass distribution and fractal dimension was established. The relationship between fractal dimension and the volume indexes of SLSM-40 was analyzed, and the mechanical indexes of SLSM-40 were studied by using strength test and simple performance test. Analysis result shows that all the volume indexes of SLSM-40 satisfy technical requirements when fractal dimension is about 2.60. SLSM-40 has good gradation homogeneity when fractal dimension is 2.55-2.60. Cohesion increases with the increase of particle size, and the contribution rate of SLSM-40 cohesion to overall strength is about 50%, which increases by 1-2 times compared with ordinary asphalt mixture, and internal friction angles reduce by 5°-10°. The compression rebound modulus of SLSM-40 increases by 1 869 MPa at 20 ℃, which is 2.6 times compared with AC-25. The dynamic modulus of SLSM-40 increases with the increase of loading frequency at different temperatures, and the change law of phase angle has larger difference compared with that of dynamic modulus at different temperatures and loading frequencies. Dynamic modulus index decreases with the increase of temperature, and the resistance to permanent deformation ability of SLSM-40 declines.More>

2013, 13(1): 7-14. doi: 10.19818/j.cnki.1671-1637.2013.01.002

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Stability analysis of rock slope based on improved Sarma method

ZHOU Zhi-jun, NIU Yong, ZHANG Tie-zhu

Abstract: The glide of simple heterogeneous rock slope was taken as research object, a mechanical model based on Sarma method was built. According to the static equilibrium condition of rock slope block, the relationship between critical acceleration coefficient and lateral normal pressure was got. The formula of critical acceleration coefficient was deduced, and the safety stability factor of slope under the condition of seismic intensity was got. The function relationship between safety stability factor and critical acceleration coefficient was analyzed, and the traditional Sarma method was improved by using the function relationship. Calculation result shows that the function relationship between safety stability factor and critical acceleration coefficient is monotone decreasing. Compared with the traditional Sarma method, the improved Sarma method does not need iteration, and does not exist convergence problem. The calculation number of example is only 6, and the calculation result meets requirement.More>

2013, 13(1): 15-19. doi: 10.19818/j.cnki.1671-1637.2013.01.003

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Effect analysis of steel-concrete composite beam caused by sudden change of temperature

ZHOU Yong-chao, HU Sheng-neng, SONG Lei, LI Zi-qing

Abstract: The temperatures of steel-concrete composite beam cross-sections under nature condition were tested, the formulae of steel-concrete composite beam interfacial shear force, shear stress, relative slide strain and deformation, flexural deformation curvature were derived by using temperature gradient calculation model and elastic theory. Analysis result shows that there is temperature difference in the cross-section, and the temperature distribution of concrete flange slab is uneven. The maximum interfacial shear force is at the midspan and decreases to zero at the end of beam. The maximum interfacial shear stress, relative slide strain and deformation are at the end of beam and decrease to zero at the midspan. Interfacial force and deformation are linearly proportional to temperature difference, and the slope is associated with the temperature distribution modes of concrete slab. The temperature distribution mode and thickness of concrete slab are the main influence factors of interfacial force and deformation.More>

2013, 13(1): 20-26. doi: 10.19818/j.cnki.1671-1637.2013.01.004

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Simulation method of random ground motion for large-span bridge in service

ZHAO Jun, NIU Di-tao

Abstract: Considering the influence of bridge structure service period on earthquake loading, equal exceeding probability method was applied to reduce earthquake role, and two fortification criterions of current anti-seismic code for highway bridge were supplemented to three levels. The probability theory was used to randomize target response spectrum by considering the randomness of ground motion. Combined with coherence function and phase difference spectrum theory, the non-stationary random ground motions of spatial correlation multi-points for existing bridge structure were generated by using MATLAB programming. Simulation result indicates that ground motion peak acceleration can be reduced rationally by using equal exceeding probability method. Probability theory can be used to get random response spectrum, which can well simulate the randomness of ground motion, and the variation coefficient maximum difference value of thirty random response spectrums is 0. 064, it meets accuracy requirement. The calculating response spectrums fit well to random target response spectrums, the goodnesses of fit for points No. 1 and No. 2 are 0.82 and 0.81 respectively, they meet accuracy requirement. The artificial ground motions can reflect the service period of existing bridge structure and therandomness of ground motion, and are similar to actual earthquake records. 7 tabs, 12 figs, 23 refs.More>

2013, 13(1): 27-35. doi: 10.19818/j.cnki.1671-1637.2013.01.005

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Influence of axle-box positioning deviation on partial wear of locomotive wheel flange

MA Wei-hua, QU Tian-wei, LUO Shi-hui, SONG Rong-rong

Abstract: The dynamics model of 2C₀ locomotive was set up, wheelset axle-box positioning deviations were analyzed, and the influence of each wheelset axle-box positioning deviation on wheelset lateral displacement and wheelset deflection direction for the same bogie was simulated. Simulation result shows that the axle-box positioning deviation of the first wheelset has greater influence on its lateral displacement, the middle and third wheelset have greater influence on the lateral displacement of the middle wheelset, and the lateral displacement can reach 6.0 mm when the positioning deviation is 2.4 mm. When the deviations exist in any two wheelsets at the same time, the anti-phase positioning deviation has greater influence and more easily results in the partial wear of wheel flange than the same phase positioning deviation, and the lateral displacement can reach 6.5 mm when the combined axle-box positioning deviation is 1.6 mm. The partial wear can be effectively improved by adjusting the positioning deviation.More>

2013, 13(1): 36-41. doi: 10.19818/j.cnki.1671-1637.2013.01.006

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Hull form's optimization method of unmanned surface vehicle

MA Wei-jia, SUN Hua-wei, PANG Yong-jie, GUO Zhi-qun, YANG Heng

Abstract: To calculate and optimize the resistance performances of unmanned surface vehicle at middle-low speeds, a calculation method of wave-making resistance in running state was proposed in considering nonlinear and viscid effects on the free surface. Based on the linear wave-making resistance theory, the hull form optimization with constrains was converted to a mathematical optimization, by which the functional extremums under specific constrains could be gotten, and the optimal ship form could be calculated by minimizing the objective function under the constrains of specific principle parameters according to the nonlinear layout optimization theory. Theoretic calculation and test results show that the new method is more effective and faster to calculate the wave-making resistance. Optimized hull form has smaller wave-making resistance coefficient in the specific speed range(Froude number is in 0.1-0.7). Compared with the original hull form, the coefficient reduces by about 20% at the optimizing speed(Froude number is 0.5).More>

2013, 13(1): 42-46. doi: 10.19818/j.cnki.1671-1637.2013.01.007

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Influence of underwater towed system on ship maneuverability

JIN Liang-an, YUAN Zhi-jiang, CHI Wei, TIAN Heng-dou, LU Yi-bin

Abstract: Towing ship, towed cable and towed vehicle were treated as an interactional whole system. Using the boundary conditions of the system, the tensions and moments of towed cable's upper end and bottom end were used into the MMG model of towing ship and the equation with six degrees of freedom for towed vehicle respectively. Coupled with the finite difference method of towed cable, a coupling motion model of the whole system was established. A numerical method was developed based on the mode[to predict the influence of underwater towed system on the maneuverability of towing ship. Numerical result indicates that the velocity of towing ship decreases by considering the coupling function of towed cable and towed vehicle in steady motion, and the variation is 3O//oo-5%. In the turning maneuver of towing ship, the velocity, turning radius and roll angle of towing ship reduce, and the variations are 2;-3;/0, 2;-4;//0 and 11%-21% respectively. The influence makes the maneuverability more normal. Moreover, it can be used as the basic theory to predict the behaviors of underwater towed system. 7 tabs, 6 figs, 15 refs.More>

2013, 13(1): 47-54. doi: 10.19818/j.cnki.1671-1637.2013.01.008

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Variation characteristic of wheel cylinder pressure in electro-hydraulic braking system controlled by PWM signal

XU Zhe, WEI Min-xiang, LI Yu-fang

Abstract: In order to decrease the variation amplitude of wheel cylinder pressure for electro-hydraulic braking system(EHB), the pressure variation rate was represented by the stable pressure variation value, and the variation law in the working range was investigated. The formula to calculate the stable pressure variation value was deduced, some experiments were carried out to measure the stable pressure variation values under different initial pressures and duty cycles. Calculation result shows that the curves of the rates have inflection points according to the initial pressures. At the left side of every inflection point, the pressure variation rate increases with the increase of initial pressure. While at the right side, the rate decreases. The inflection points at different duty cycles appear at the nearly same cylinder pressure. As the inflection point is caused by piston motivation, it is named as piston motivation's end pressure. In the system, it is about 2.9 MPa. The relationship between the pressure rate and the duty cycle is approximate linear in working pressure range.More>

2013, 13(1): 55-61. doi: 10.19818/j.cnki.1671-1637.2013.01.009

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Equilibrium assignment model of integrated transit network

LI Shu-qing, LI Zhe, ZHU Wen-ying

Abstract: The traffic characteristics of integrated transit network were analyzed, the impacts of trip time and cost on trip impedances were studied based on the path features of integrated transit network. By considering the impact of passenger flow density on walking speed and the conversion relation between travel cost and time, the section impedance, node impedance and cost impedance were transformed to time, and the trip impedance function of integrated transit network was set up. By using Wardrop equilibrium theory, an equilibrium assignment model was established, and the model was solved according to FW algorithm. Computation result indicates that when the lengths of bus transit and rail transit are 57.3, 16.2 km respectively, the ratio of passenger flow volume by rail transit and total passenger flow volume is 65.4%, and 55.4% passengers get access to rail transit system through transfer. So by constructing reasonable integrated transit network, the total trip impedance reduces and the transportation efficiency of transit network improves.More>

2013, 13(1): 62-69. doi: 10.19818/j.cnki.1671-1637.2013.01.010

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Separation determining method of closely spaced parallel runways

TIAN Yong, SUN Jia, WAN Li-li, LI Yong-qing

Abstract: By using wake vortex movement characteristics under the most adverse environment, the effects of the slant range and approach glide angles of paired aircrafts and aircraft type combination on runway separation under the dependent parallel approach mode of closely spaced parallel runways were researched, the minimum wake vortex separation standard and crosswind statistical data of NASA were used, and the determination methods of runway centerline distance and threshold offset were put out based on aircraft type parameters. Analysis result shows that when the slant separation standard of paired leading and trailing aircrafts is a certain value, threshold offset decreases with the increases of runway centerline distance and the glide angle of paired trailing aircraft. When the glide angles of paired leading and trailing aircrafts are same, threshold offset decreases with the increases of runway centerline distance and slant separation standard. When runway centerline distance is 380 m, the glide angles of paired leading and trailing aircrafts are both 3°, and slant separation standard is 2 780 m, the threshold offset of Changsha Huanghua International Airport should be more than 1 483 m, which is accord with the runway parameter of foreign authorized airports.More>

2013, 13(1): 70-76. doi: 10.19818/j.cnki.1671-1637.2013.01.011

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Constraint programming model of integrated recovery for aircraft and crew

ZHU Bo, ZHU Jin-fu, GAO Qiang

Abstract: The features and differences of running schedules for aircraft and crew were analyzed. The mininum total recovery cost was taken as objective function, the spatial-temporal connection and flow balance of aircraft, flight, crew and airport were considered as constraint conditions, and the constraint programming model of integrated recovery for aircraft and crew was built. Aiming at the characteristics of integrated recovery problem and model structure, the searching algorithm was designed by using mixed set programming method, and example verification was carried out. Calculation result indicates that for small scale example, the results obtained by the proposed model and sequential recovery method are same, and the delay is 6 020 min. For medium and large scale examples, the delays obtained by the proposed model and sequential recovery method are 9 670, 12 840 min respectively, and the delay obtained by the proposed model reduces by 24.69% compared with the result of sequential recovery method. By using sequential recovery method, 22.2% examples can not obtain feasible solution. So the proposed model is feasible.More>

2013, 13(1): 77-83. doi: 10.19818/j.cnki.1671-1637.2013.01.012

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Optimization model of existing stop schedule for high-speed railway

FENG Xu-jie, SUN Quan-xin, FENG Jia, WU Ke-qi

Abstract: The influences of stop schedule on traction energy consumption and travel time for high-speed railway train were analyzed. The calculating methods of estimating train traction energy consumption were summarized. The service frequency and stop schedule were converted into stop times, the mechanical efficiency was introduced, and the calculating method of estimating train traction energy consumption based on doing-work process was improved. The minimum traction energy consumption and the shortest travel time were taken as optimization objectives, the existing transportation supply was taken as constraint condition, and the optimization model of existing stop schedule was established. Huhang High-speed Railway was taken as a case, and the validity of the proposed model was verified. Reasearch result shows that the stop schedule with the minimum traction energy consumption prefers through trains, the number of stop times reduces, and the number of maximum stop times at intermediate stations is three.Although travel time increases 14 min more than existing stop schedule, traction electricity reduces by 559 kW·h per day. In the stop schedule with the shortest travel time, the number of through train is 0, but the rate of train frequencies with one stop times at intermediate stations is 74.4%. Travel time reduces by 12 min and traction electricity increases by 3 299 kW·h per day. The stop schedule with the minimum traction energy consumption and the shortest travel time has an insignificant improvement effect compared with the existing stop schedule.More>

2013, 13(1): 84-90. doi: 10.19818/j.cnki.1671-1637.2013.01.013

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Influence of trip cost on trip mode for resident

XU Ting, LAN Jin, HU Da-wei, SUN Xiao-duan, WANG Wei-li

Abstract: The trip behaviors of residents in Beijing city were taken as study subject, the basic trip data of some regions in 2010 were collected, and correlation analysis was used to choose influence factors which were closely related to the mode choice of resident trip. New utility function was constructed by using the difference value of utility functions of public transit trip mode and car trip mode. The salary, trip purpose, payment mode, trip time ratio and trip cost ratio were taken as influence factors. The trip time ratio of car trip mode and public transit trip mode was divided into 3 conditions such as 1:5, 1:3 and 1:1, and the influence of trip cost on trip mode for resident was analyzed. Ayalysis result shows that when trip time ratio is 1:5, all the elastic values of car trip mode are less than 0.1, and trip cost adjustment is invalid. When trip time ratio is 1:3, the maximum elastic value of car trip mode is 0.39. When trip cost ratio is 25, 40%-50% residents will still use cars. When trip time ratio is 1:1, the maximum elastic value of car trip mode is 0.89. When trip cost ratio is 22, 40%-50% residents will still use cars. If trip time ratio is between 1:1 and 1:3, car trip sharing rate is forced down to 30%, trip cost ratio must be 5 at least.More>

2013, 13(1): 91-97. doi: 10.19818/j.cnki.1671-1637.2013.01.014

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Dynamic extraction method of saturation flow rate at signalized intersection

YANG Dong-yuan, LUO Jiang-lin, LIU Chong, DUAN Zheng-yu

Abstract: The dynamic extraction method of saturation flow rate by using induction coil detector was proposed. Taking the time difference of the front vehicle and the following vehicle when departing from an induction coil detector as headway, the average saturation headway from the fourth vehicle to the last vehicle in saturation state was calculated. The average saturation headways of history and current cycle were dealt with exponential smoothing method. Thresholds for judging vehicle type and saturation headway were determined. When the occupation time of a vehicle was more than twice of the average occupation time of small vehicle, the vehicle was judged as large vehicle. The threshold of saturation headway for small vehicle was historical average saturation headway adding 1 s, and that of large vehicle was historical average saturation headway adding 5 s. The validity of the proposed method was testified by using software VISSIM. Simulation result indicates that the dynamic extraction method can reduce the sudden change influence of saturation headway. When the saturation headway suddenly decreases by 31.3% in current cycle, the saturation flow rate only increases by 5.6%, and the saturation flow rates in 5 cycles are 1 782, 1 682, 1 600, 1 690, 1 773 veh·h^-1 respectively, nevertheless, the rate of HCM model is 1 680 veh·h^-1. Compared with the traditional methods, the method meets the demand of dynamic extraction, and the implementation of the method is low-cost.More>

2013, 13(1): 98-103. doi: 10.19818/j.cnki.1671-1637.2013.01.015

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Vehicle positioning using GPS/CP and intersection collision detection

AN Yi, NING Bin, CAI Bo-gen, SHANGGUAN Wei, WANG Jian

Abstract: As GPS was constrained for moving vehicle in urban road, a tightly coupled positioning method based on cooperative positioning(CP)and height constrained model was presented. Vehicle status informations were shared by vehicle and infrastructure based on dedicated short-range communication(DSRC)at the intersection, and an intersection collision detection method was proposed based on the cooperative communication of vehicle to vehicle(V2V)and vehicle to infrastructure(V2I). The simulation environments based on scenario were constructed to validate the performance of GPS/CP and intersection collision detection method, and integrated positioning simulation and multi-scenario intersection collision detection were carried out. Simulation result indicates that the positioning error of vehicle is less than 3 m when visible satellite number reduces. The number ofcollision vehicles and vehicle collision rates decrease, traffic volume slightly declines when vehicle number is 20 and also no positioning error exists at the intersection. Vehicle positioning error must be less than 6 m to achieve collision detection. Based on comprehensive utilization of higher positioning accuracy using GPS/CP and a safer collision detection method based on V2V/V2I, low vehicle collision rates and high traffic capacity at the intersection can be got.More>

2013, 13(1): 104-113. doi: 10.19818/j.cnki.1671-1637.2013.01.016

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Moving vehicle location method based on traffic wireless sensor network

LAI Lei, QU Shi-ru

Abstract: To improve the location reliability and accuracy, moving vehicle location system based on traffic wireless sensor network was studied. Based on the law that vehicle location changed along with its speed, a variable interval quantum particle swarm optimization algorithm was proposed, by which the measured vehicle location parameters could be used for the rough estimation of vehicle coordinates. For the noise interferences and signal delay, the rough estimated values of vehicle coordinates were always prone to error. The current statistical model was introduced into the algorithm under the motion constraints of vehicle, and the extended Kalman filter was used to eliminate the location errors. The proposed method was tested by the evaluation indexes of speed and accuracy. Tested result indicates that the location reliability is improved for that the enormous sum nodes of wireless sensor network can be disposed. The variable interval introduced into the quantum particle swarm optimization increases the convergence speed by 39.13%. The Kalman filter corrects the errors, and improves location precision by 56.48%. The proposed algorithm demonstrates the superiority in terms of location reliability and accuracy.More>

2013, 13(1): 114-120. doi: 10.19818/j.cnki.1671-1637.2013.01.017

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Vehicle license plate location using active learning AdaBoost algorithm and color feature

ZHANG Xiao-na, HE Ren, CHEN Shi-an, YAO Ming

Abstract: A small amount of license plate areas and non-license plate areas were selected, and Haar-like extended features were extracted by using the integration diagram method to obtain initial training samples. An initial classifier was generated by training the samples with AdaBoost algorithm. A strong classifier for license plate detection was obtained in the active learning procedure. The coarse location of license plate was implemented by using the cascade structure detection method. The candidate region was verified to get the precise location of license plate area by extracting edge-color pairs. The method was applied into the test of vehicle license plate location under different illumination and defaced circumstances. Test result indicates that the coarse location rate of license plate is 98.3%, the precise location rate is 97.1%, and the average location time is less than 0.1 s. A better license plate location effect and accuracy are achieved by the proposed method.More>

2013, 13(1): 121-126. doi: 10.19818/j.cnki.1671-1637.2013.01.018

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