2014 Vol. 14, No. 3

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Road and railway engineering
Relationship among asphalt component, viscosity and adhesion in triangular coordinate system
FU Zhen, YAN Xi-li, CAI Ting, MA Feng, WANG Lin-bing
Abstract: In order to assess the influences of asphalt component and composition on asphalt technical properties, thirteen types of pavement petroleum asphalts and two kinds of typical aggregates were selected.The relationship among asphalt component, viscosity and adhesion was investigated by using tests of four-component, apparent viscosity and adhesion.The characterization method of asphalt four-component test result by using triangular coordinate system was put forward.The asphalt characteristic triangle was drawn with four-component data.The characteristic of asphalt composition was represented by inertia moment.The asphalt pyramid was drawn based on asphalt four-component data and the relationship among its geometry characteristics, viscosity and adhesion was analyzed.Analysis result indicates that except asphalt components, its composition differences also have influences on asphalt viscosity and aggregate adhesion.For the asphalts with same penetration grade and different brands, triangular coordinate analysis result shows the aggregate adhesion increases with the increase of the inertia moment of asphalt four-component characteristic triangle.More>
2014, 14(3): 1-7.
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Ground vibration characteristic of embankment section for fast railway
ZHANG Guang-ming, HE Yu-long, YANG Li-zhong, SU Kai
Abstract: The ground vibration induced by trains running on the embankment of Chengguan Fast Railway was measured through field test.The maximum vibration levels, equivalent vibration levels and vibration frequencies in various locations induced by trains running from inside and outside tracks were analyzed.The orrelation of decy speed and vibration frequency was studied, a new frequency-division section prediction method based on Bornitz model for railway embankment ground vibration was built and verified.Analysis result indicates that the levels of the maximum vibration is 51-77 dB in the distance away from embankment 5-75 m, which meets the requirement of current railway environmental vibration standard.The environmental vibration induced by train running on inside track is greater than that on outside track.The ground vibration attenuates quickly in the region less than 35 m away from embankment, and the attenuate rate of ground vibration become slower in the region more than 35 m away from embankment.High frequency vibration is the major vibration phenomenon within the scope of nearby embankment.In the site of 5 m away from embankment, the dominate vibration frequency range is from 16 Hz to 100 Hz.The low frequency vibration less than 4 Hz is the main vibrationphenomenon in the region of more than 65 m away from embankment.The phenomenon of vibration rebound mainly occurs in the frequency range of less than 20 Hz or greater than 100 Hz.The prediction method has good prediction accuracy.More>
2014, 14(3): 8-14.
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Assessment of weathering degree and road performance test of weathered rock as subgrade filling
GUO Yin-chuan, SHEN Ai-qin, GAO Tao, LI Wei-guang
Abstract: Four kinds of typical weathered rocks were selected.Their gradation compositions, compaction parameters and fragmentation properties were analyzed.The affecting factors of longterm stability of weathered rock were researched.Water-temperature cycle test method was developed to simulate the natural weathering of subgrade filling.The influence of weathering degree on CBR (California bearing ratio) and water-temperature sensitivity and the influence of water-temperature cycle effect on the properties of weathered rock were researched.Combining physical and chemical weathering evaluation methods, weathering characteristic index was proposed to evaluate the weathering degree.The correlations between weathering characteristic index and road performances of weathered rock were analyzed.The grading standard of the weathering degrees based on the road performances was established.Analysis result shows that when the weathering degree increases, the mechanics performances and water-temperature sensitivity of weathered rock reduce.The long-term road performances of weathered rock can be distinguished by using water-temperature cycle test method.The determination coefficients between weathering characteristic index and road performances are greater than 0.85, so theircorrelations are good, and the index is available to judge the weathering degree and road performances of weathered rock.When the weathering characteristic index is 0.78, after 18 months, the maximum settlement of test road with weathered rock subgrade is 7.8 cm, so its road performances are well.More>
2014, 14(3): 15-23.
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Vertical soil arch effect analysis and soil pressure calculation behind piles for pile-anchor supporting system
WU Chong-fu, LI Yu, ZHANG Zhi-jun
Abstract: Aimed at the vertical soil arch effect of pile-anchor retaining structure, the formation mechanism and geometric characteristics of vertical soil arch and its influence on soil stress distribution were analyzed by using the mechanical equilibrium condition of soil arch.In indoor model test, soil stress field distributions at different excavation stages were obtained by monitoring.The existence of vertical soil arch was proved by comparing the test data, the monitoring data and the theoretical values.Based on the vertical soil arch effect, the expressions of soil stress distribution behind pile were derived by adopting the oblique soil element method, and the computed values were analyzed based on the classic theory computation values and the test data.Study result shows that the gravity stress curve of soil attenuates between anchors.There are relative peaks on lateral stress curve at anchor supporting point behind pile.Vertical soil arch appears above the bolts, and has significant effect on soil stress redistribution.The soil pressure distribution law calculated by the oblique soil element method considering vertical soil arch effect is consistent with the test result, the biggest soil pressure difference at the same depth of two curves is less than 15%, which proves that the calculating method of soil pressure is accurate.More>
2014, 14(3): 24-33.
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Chaos characteristics of wind-induced vibrations for bridge
LI Jia-wu, WANG Xin, ZHANG Yue, GAO Meng, CHEN Zi-tao
Abstract: According to nonlinear theory and chaotic time series analysis method, the mathematical model of bridge wind-induced vibration was built.The MATLAB program for calculating the Lyapunov exponent of bridge vibration acceleration time series was developed, and the flutter and vortex vibration were tested in wind tunnel.Under various wind attack angles, the damping ratios of bridge wind-induced vibrations, the relationships between Lyapunov exponents and wind speeds, and the relationships between vortex vibration amplitudes and wind speeds were analyzed, and the chaos characteristics of flutter and vortex vibration were studied.Test result indicates when wind speed is less than critical wind speed (15.5 m·s-1), the Lyapunov exponent is negative in flutter test, and the close correlation between Lyapunov exponent and damping ratio is found.When wind speed increases from 3 m·s-1 to 18 m·s-1, the phase space becomes divergent gradually.In vortex vibration test, when wind speed increases from 4.5 m·s-1 to 8.5 m·s-1, the Lyapunov exponent is more than 0, obvious vortex vibration happens, and multi-frequency vibration turns to single frequency vibration gradually.The phase space also becomes an ideal circle.Both flutter and vortex vibration are chaos phenomena.Lyapunov exponent at low wind speed can be used to predict the wind-induced vibrations at high windspeed, and the phase space can also be used to explain flutter and vortex vibration.More>
2014, 14(3): 34-42.
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Transportation vehicle engineering
Calculation method of accurate wheel-rail contact relationship of worn wheel tread
GAN Feng, DAI Huan-yun, GAO Hao
Abstract: Base on wheel-rail rigid contact, a calculation method of quasi-elastic contact was presented.TPLWRSim software was developed based on the contact method to calculate the wheel-rail contact relationships of standard and worn tread of high-speed EMU respectively, and the calculation results were compared with the results of SIMPACK software.Analysis result indicates that the maximum modified value of quasi-elastic contact point abscissa for standard S1002CN tread is 5.26 mm, and the value is 11.10 mm for worn tread.For standard LMA tread, the maximum modified value is 3.82 mm, and the value is 13.14 mm for worn tread.Wheel-rail quasi-elastic contact relationships calculated by TPLWRSim and SIMPACK are basically identical.Wheel-rail quasi-elastic contact can better change the characteristic of rigid contact with sharp, discontinuity and large dispersion contact point, and makes the contact point more smooth and continuous.The calculation result can be used for the track test of worn tread, and will have very good practicality.More>
2014, 14(3): 43-51.
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Performance parameter estimation method of high-speed train based on Rao-Blackwellised particle filter
DING Jian-ming, LIN Jian-hui, WANG Han, HUANG Chen-guang, ZHAO Jie
Abstract: In order to solve the nonlinear problems caused in augmenting the state vector of the performance parameters of high-speed train, a method of parameter estimation based on RaoBlackwellised particle filter (RBPF) was developed.Under the framework of Rao-Blackwellised (RB) principle, the probabilistic model of parameter estimation was divided.The Kalman filter (KF) was applied for the prediction time step and measurement update of linear state block and the RBPF was applied for the prediction time step and measurement update of nonlinear parameter block to realize the dynamic estimation.Through theoretical analysis and parameter estimation example of high-speed train, the validity of RBPF method for parameter dynamic estimation was verified.Analysis result shows that compared with the classical extended KF (EKF) method, RBPF method has the characteristics of initial immunity and algorithm stability.RBPF method shows its good engineering applicability for the minor parameter estimation error which is less than 5%, and inexistence of estimation deviation.More>
2014, 14(3): 52-57.
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Improved draft survey method based on densified table of offsets
LIU Chun-lei, ZHANG Xiu-feng, SUN Xiao-feng, YIN Yong
Abstract: In order to improve the accuracy of draft survey, an improved draft survey method that did not depend on ship loading manual was developed.The displacement of ship was calculated by using high-precision ship database that was established based on the densified table of offsets.The floating state parameters and sagging (hogging) value of ship were calculated according to six draft readings.In order to calculate the sagging (hogging) value of each station, the deformation curve of ship was fitted by circular arc according to the beam bending theory in material mechanics.The ship database in sagging (hogging) condition was constructed by the correction of offsets coordinate point.The displacement of ship in free floatation was calculated by using floating state parameters, coordinate system transformation and S-H polygon clipping algorithm.Taking a bulk carrier as an example, the displacements of ship in even keel, trim and hogging condition were calculated respectively, and compared with the calculation result of traditional draft survey method.Calculation result indicates that in even keel condition, the average relative error of improved draft survey method is smaller, about 0.085 6%, the average relative errors increase to 0.414 5% and 0.619 9% in trim and hogging condition respectively.The calculation accuracy of improved draft survey method increases, the method can be applied tofree floatation of ship, and has a certain engineering application value.More>
2014, 14(3): 58-64.
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Design of turbine blades of torque converter based on reverse technology
LIU Zong-qi, LI Zhi-yuan, XIA Guang
Abstract: In order to shorten the design cycle of torque converter and reduce the dependence of experience in design, the reverse technology was used to calculate and analyze the data of turbine's stamping blades.Based on the generalized torus coordinate system of liquid flow, the mathematical expression of blade design baseline was deduced, the machine coordinates of blade were obtained accurately on both inside and outside rings, and the original characteristic expression of new torque converter was described.Then, new torque converter with designed blades was tested and compared with prototype.Test result indicates that new converter efficiency and torque ratio with new turbine blades are only 0.5% lower than prototype, and the torque coefficient is only 1% lower.The error between new blade and origin one is less than 0.605 2%.Therefore, the torus and axial surface equations obtained from torus coordinate system is accurate.This method offers a new choice to ensure the reliability of product and shorten its cycle in the design of torque converter.More>
2014, 14(3): 65-72.
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Antiwear property measuring method of lubricant based on wear scar detection
XIAO Mei, ZHANG Lei, HAN Guang, YANG Jing-shuai, LIU Long
Abstract: In order to measure the antiwear property of lubricant, a measuring method of steel ball wear scare diameter was presented based on gradient information.Because of steel ball wear scar region had rich and same direction wear scars, the texture gradient images of wear scar were extracted by using four direction gradient template.The steel ball wear scare region was automatically separated from the wear scar texture gradient image by the processings of binary, close operation, removing sporadic regions and filling holes.The equivalent diameter of wear scar region was obtained by using the calculated wear scar region area of steel ball.The antiwear properties of lubricant were fast measured through the calculated wear scar diameter.Qualitative and quantitative tests were carried out to the wear scar detection result, and the result was also compared with the traditional microscope measurement result.Analysis result indicates that the wear scar area of extraction method is complete and the edges are clear.The average error of traditional microscope measurement method is 4.015%, the average error of extraction method is 0.073%, so the extraction method has high measurement accuracy.More>
2014, 14(3): 73-78.
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Transportation planning and management
Integrated optimization model of pedestrian-public transit emergency evacuation
PAN Shu-liang, YU Jie, LIU Yue
Abstract: Aiming at emergent event in large-scale public, an integrated optimization model of emergency evacuation was developed based on public transit.In the model, the problem of emergency evacuation was summarized as a two-level optimization network including pedestrian traffic flow and public transit network.The first-level framework guided evacuees from accident sites (e.g.buildings) to designated pick-up points (e.g.bus stops).The second-level framework properly dispatched and routed a fleet of buses at different transit depots to the pick-up points, and transported evacuees to safe places finally.Integrated optimization model was tested and verified by using a two-stage heuristic algorithm based on tabu search.Verification result indicates that 8 buses are used for the evacuation of all 328 people in the network.The output result of integrated optimization model is not sensitive to the change of weight assignment of objective function, so the model has strong robustness.Comparing with the optimization software of CPLEX, heuristic algorithm can get near optimum solution in 1 h, and the error between near optimum solution and optimal solution is less than 15%.The interactions betweenevacuees distribution and bus route optimization are fully considered in the model.The pedestrian traffic flow and the public transit network during evacuation process are concurrently optimized.More>
2014, 14(3): 79-86.
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Improved K-nearest neighbor algorithm for short-term traffic flow forecasting
XIE Hai-hong, DAI Xu-hao, QI Yuan
Abstract: The original K-nearest neighbor algorithm for short-term traffic flow forecasting was analyzed.Pattern distance search method was used to replace the original Euclidean distance search method, the multiple statistics regression model was introduced, an improved K-nearest neighbor algorithm for short-term traffic flow forecasting was put forward, and an example verification was carried out by using the traffic flow data from a certain section in Beijing.Test result indicates when Kis 23, the error of mean square, mean absolute error and average relative error of forecasting results are 31.43%, 4.17% and 0.27% respectively by using the improved K-nearest neighbor algorithm.By using the original K-nearest neighbor algorithm, the error of mean square, mean absolute error and average relative error of forecasting results are 33.33%, 4.40% and 0.28% respectively.By using the historical average model, the error of mean square, mean absolute error and average relative error of forecasting results are 46.20%, 11.40% and 0.48% respectively.The forecasting accuracy of the improved K-nearest neighbor algorithm is obviously higher than the other two algorithms.The improved K-nearest neighbor algorithm notonly increases searching efficiency, but also accurately reflects the real situation of traffic flow.More>
2014, 14(3): 87-94.
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Optimization model of ground-holding problem in airport flow management
WANG Lai-jun, HU Da-wei, GAO Yang, SHI Zhong-ke
Abstract: The stochastic features of arrival capacity and arrival demand for target airport were analyzed.The minimum total flight delay cost was taken as objective function, the principle of first come first service, the limits of airport arrival capacity and the relation between groundholding and air-delay were considered as constraint conditions, and the mathematical programming model and event-driven model of grounding-holding problem in airport flow management were built.The basic genetic algorithm was designed to solve the models, the concrete arrival times after optimization were calculated.Calculation result shows that the bigger the ratio of unit air-delay cost to unit ground-holding cost is, the more easily the air-delay turns to ground-holding.When the ratio of unit air-delay cost to unit ground-holding cost is 3∶1, the total delay costs reduce by 50% after optimization.When the ratio of unit air-delay cost to unit ground-holding cost is 1∶1, the time ratio of air-delay to ground-holding is about 1.058.When the ratio of unit air-delay cost to unit ground-holding cost is 6∶1, the time ratio of air-delay to ground-holding is about 4.77%.After optimization, the flight arrival distribution is more statuesque, and the optimized result is more accurate.More>
2014, 14(3): 95-104.
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Multi-agent evolutionary algorithm of VRP problem with time window
LIU Xin-meng, HE Shi-wei, CHEN Sheng-bo, LU Chao
Abstract: Based on the angle of practicality and rationality, the vehicle routing problem with time window for single distribution center was studied.The shortest driving time and the minimum customer waiting time were taken as objective functions, the service time window and vehicle load were taken as constraint conditions, and the bi-objective optimization model was constructed. The Multi-agent evolutionary algorithm based on number coding (NC-MAEA) was used to solve the model, and the calculation result was compared with the calculation result solved by genetic algorithm.Calculation result shows that when the number of customer demand point is 13, the service time of demand point is 5 min, the maximum vehicle load is 3 t, the number of initial agent is 49 and the maximum evolution iterations is 200, the worst value is 121.8 min and the optimal value is 110.3 min calculated by using genetic algorithm after 30 calculation times.The worst value is 113.6 min and the optimal value is 103.6 min calcuated by using the propsed algorithm.It is clear that the higher quality optimal result can be gotten by using the multi-agent evolutionary algorithm, the results change little after repeated tests.More>
2014, 14(3): 105-110.
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Traffic information engineering and control
Simulation method of information interaction in CVIS
CAI Bo-gen, WANG Cong-cong, SHANGGUAN Wei, ZHANG Shu-zhong
Abstract: In order to improve the communication quality of information interaction network in cooperative vehicle infrastructure system (CVIS), and realize accurate information interaction within the limited range of time delay, the information interaction platform of CVIS was constructed based on OPNET.Different kinds of vehicular ad hoc network routing protocols were studied, and the optimized method of cluster-based routing protocol based on vehicle position was designed by using the minimum distance routing competition mechanism.The simulation results of the optimized cluster-based routing protocol based on vehicle location and the traditional routing protocol were compared based on OPNET, and the influences of different routing protocols on the communication performances of CVIS were analyzed.At the same time, two types of channel access protocols including DCF and PCF were simulated and compared.Simulation result indicates that the cluster-header change rate of cluster-based routing protocol based on vehicle position is 1.47 times·s-1.The time delays of cluster-based routing protocol based on vehicle position respectively reduce by 18.92% and 26.90% compared to AODV and DSR, and respectively reduce by 14.20% and 21.54% compared to cluster-based routing protocolbased on the highest degree and node ID.The network loads of proposed cluster-based routing protocol respectively reduce by 20.83% and 22.92% compared to AODV and DSR.The channel access protocol of PCF performs better than DCF by 29.60% in the aspect of time delay.More>
2014, 14(3): 111-119.
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Control method of underactuated surface ship formation based on stable adaptive neural network control law
LIU Yang, GUO Chen, LIU Zheng-jiang, FAN Yun-sheng
Abstract: Considering the control problems of underactuated surface ship formation with uncertain dynamics and external environment disturbances, a stable adaptive neural network control method was proposed based on leader/follower method and target tracking mechanism.A kinematics formation tracking controller was presented based on target tracking error, the dynamics equations of tracking error were derived, adaptive neural network was used to estimate the uncertainties of dynamics equations, and a stable adaptive neural network dynamics tracking controller was constructed.The Lyapunov stability theory and the series-system stability theory were used to design ship control laws and calculate ship adaptive laws so as to online adjust the weights of neural network and ensure the formation tracking error of closed loop system uniformly ultimately bounded.The formation with three ships was as an example, and the control method was tested.On circular tracking path with the radius of curvature of three times of hull length, the steering angle error is less than 15°, and the F-norm of formation trackingerror is less than 1 m. On straight tracking path, the steering angle error is less than 1°, and the F-norm of formation tracking error is less than 0.1 m.Obviously, the method is reliable.More>
2014, 14(3): 120-126.
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