交通运输工程学报

Mixing power measurement at different mixing velocities and mixing rheological model of bituminous mixture

YAN Xi-li, TIAN Hui-li, YAN Xi-le, YOU Qing-long, AI Tao

Abstract: In order to quantitatively evaluate the mixing workability and to deeply know the evolution mechanism of the strength of bituminous mixture, an experimental device of mixing power measurement at different velocities named V-P-Mixer was developed in laboratory based on the conventional mixing devices, and an experiment was carried out for the mixing rheological behavior of bituminous mixture.Based on AC-13C bituminous mixtures with different bitumen contents(0-8%), the mixing powers were measured at different mixing temperatures(130 ℃-170 ℃)and mixing velocities(20-50 r·min^-1), the power-velocity diagrams were analyzed, a visco-plastic mixing rheological model was presented, and the workability index was defined as the reciprocal of mixing viscosity.Analysis result shows that the alternating errors of electric current, voltage and power consumed during mixing are respectively 2.25%, 0.11% and 5%, and the repeatability error is 0.25%, so the measurement is stable and reliable to characterize themixing power of bituminous mixture; the mixing rheological property obeys the linear Bingham model, in which the straight slope represents the general viscosity of bituminous mixture, and the reciprocal of the viscosity is defined as the workability index; when the temperature increases by 10 ℃, the mixture's viscosity decreases and the workability index increases by 10%-20%, so it is easier to mix; the mixing power and resistance increase with the increase of bitumen content, and the workability index decreases by 5%-25% when the bitumen content increases by 1%;aggregate plays plastic role, and bitumen plays viscous role in the strength mechanism of bituminous mixture.More>

2016, 16(3): 1-7. doi: 10.19818/j.cnki.1671-1637.2016.03.001

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Mechanical property of asphalt mortar with additive

NIU Dong-yu, HAN Sen, LI Xing, LI Bo, REN Wan-yan

Abstract: By the stress-strain data of compression test, the laws of stress response, the loss indices of strength and the chemicophysical causes for influencing the mechanical properties of 70^# asphalt mortar, 90^# asphalt mortar, rubber asphalt mortar and their corresponding mortars with additive were studied under the normal and freezing-thawing conditions, and the physical essences of material damage and the durabilities of six kinds of mortars during the compression process were analyzed based on the principle of energy conversion and the energy index.Analysis result indicates that the maximum stresses of rubber asphalt mortar, 70^# asphalt mortar and 90^# asphalt mortar with additive are 1.345, 1.218 and 1.186 MPa respectively, and they are 1.12, 1.18 and 1.30 times bigger than the values of corresponding mortars without additiverespectively.The increments of energy release coefficients of rubber asphalt mortar, 70^# asphalt mortar and 90^# asphalt mortar with additive are 0.152, 0.067 and 0.054 MPa^-1· J^-1respectively, they are 68.8%, 78.8% and 41.9% of the values of corresponding mortars without additive respectively.So adding additive can improve the compressive strength and mechanical durability of asphalt mortar under the normal condition.Under freezing-thawing condition, the maximum stresses of rubber asphalt mortar, 70^# asphalt mortar and 90^# asphalt mortar with additive are 1.311, 1.170 and 1.083 MPa respectively, and they are 1.22, 1.11 and 1.06 times bigger than the values of corresponding mortars without additive respectively.The increments of energy release coefficients of rubber asphalt mortar, 70^# asphalt mortar and 90^# asphalt mortar with additive are 0.221, 0.070 and 0.073 MPa^-1·J^-1 respectively, and they are 61.7%, 72.9% and 65.2% of the values of corresponding mortars without additive respectively.The smaller the energy releasing coefficient is, the better the fatigue performance is.Therefore, adding additive improves the water stability, reduces the freezing-thawing damage, and ensures the mechanical properties and durability of asphalt mortar after freezing-thawing.More>

2016, 16(3): 8-16. doi: 10.19818/j.cnki.1671-1637.2016.03.002

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Influence of key factors in construction on pavement performances of epoxy asphalt concrete

XUE Yong-chao, QIAN Zhen-dong

Abstract: In order to study the comprehensive relationship between the key factors in construction and the pavement performances of epoxy asphalt concrete, the variation of key factors in construction was simulated, and the multi-index orthogonal experiment was carried out in the laboratory.The key factors included mass ratio of component A(the epoxy resin)to component B(the mixture of petroleum asphalt and curing agent)in epoxy asphalt, asphalt-aggregate ratio, aggregate gradation, molding time of concrete, molding temperature of concrete, and compaction work.The multiple indexes included high-temperature stability, low-temperature anti-cracking performance, fatigue resistance performance, water permeability, skid resistance, and moisturesusceptibility.The improved grey situation decision was used to calculate the grey comprehensive relevancy between the pavement performances of every situation in orthogonal experiment and the optimal situation, and the range and the variance were analyzed by using the statistical product and service solutions(SPSS)software.Analysis result shows that the grey comprehensive relevancy of situation 4 is 0.943 7 and 0.081 1 larger than the value of situation 3, which indicates that the relational closeness between each situation and optimal situation changes significant.Based on the grey comprehensive relevancy of every situation, 18 kinds of schemes making specimens are ranked from good to bad.The range of molding time is 2.857, while the range of aggregate gradation is 1.555, and the larger difference of 1.302 between the two key factors shows that the influences of different key factors in construction on the pavement performances are different.Based on the ranges, key ranked factors are molding time of concrete, asphalt-aggregate ratio, mass ratio of component A to component B, compaction work, molding temperature of concrete, and aggregate gradation according to the influences from big to small.By comparing the average values of grey comprehensive relevancies of each level of all key factors, the determined best construction scheme is that the mass ratio of component A to component B is 1∶2.9, asphalt-aggregate ratio is 6.5%, the passing rate of 2.36 mm of aggregate gradation is the median of design value, molding time is 55 min, molding temperature is 120 ℃, and compaction work is 24 times.The F test value of every key factor in variance analysis is bigger than 19, so key factors and their levels have good conspicuousness.Obviously, the improved grey situation decision can be used to effectively evaluate the pavement performances of epoxy asphalt concrete under different construction schemes, and to determine the influence degrees of key factors in construction on the pavement performances of epoxy asphalt concrete and the best construction scheme combined with the range analysis.More>

2016, 16(3): 17-27. doi: 10.19818/j.cnki.1671-1637.2016.03.003

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Interlayer combination state of double-layer continuous paving semi-rigid base

QIAO Zhi, WANG Xuan-cang, ZHANG Zhi-fang, ZHAO Sheng, LIU Zu-chen, XU Zi-tao

Abstract: In order to improve the service life of road base in cold area, the bonding mechanism of semirigid base was studied, and the direct shear mould for base layer specimen was designed.Based on the tests of tensile strength and shear strength of base layer, the influences of different paving methods on the combination effect of base layer were analyzed.By using software BISAR3.0, different interlayer friction coefficients were set, the distributions of tensile stress at the bottom of each structure were calculated under different interlayer combination states.The fatigue equations of asphalt mixture and water stable crushed stone mixture suitable for northern cold area were put forward, and the service lifeof pavement under double-layer continuous paving process was calculated.Calculation result indicates that when using double-layer continuous paving, the tensile property of base layer specimen increases by 1.8 times compared with traditional specimen, but only 37.9% of the tensile strength of standard specimen is achieved.There is a certain gap between double-layer continuous paving and ideal state(completely continuous).For the shear strength, the effect of double-layer continuous paving increases by 7.3 times compared with traditional paving process.The performance of road base is effectively improved by using double-layer continuous paving construction.With the increase of interlayer friction coefficient, the tensile stress at the bottom of each structure decreases.Therefore, the combination effect of semi-rigid base layer can be effectively improved by using double-layer continuous paving, which can improve the stress distribution of the bottom of layer and increase the service life of pavement structure by 16.1%-47.4%.More>

2016, 16(3): 28-34. doi: 10.19818/j.cnki.1671-1637.2016.03.004

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Flexural behaviors of composite continuous box-girder with corrugated steel webs, double concrete filled steel tubular chords and concrete slabs

DONG Jie-can, CHEN Yi-yan, BRISEGHELLA Bruno, WU Qing-xiong, WANG Meng-yu

Abstract: A new composite structure composed of corrugated steel webs(CSW), double concrete filled steel tubular chords(CFST)and concrete slabs(CS)was presented.To understand the flexural behaviors under positive and negative bending moments, the experiments of new composite continuous box-girder were carried out, and the failure modes and deflection patterns of the girder, and the development rules of concrete plate cracks were studied.According to the test results, the calculation methods of deformation and bearing capacity of the new type of composite girder were put forward and verified.Experimental result shows the strain peak values of mid-span and intermediate support are only 3.7% and 5.1% of the value of bottom steel concrete pipe chord respectively, therefore the longitudinal strains of corrugated steel webs are small and negligible in the positive and negative bending moment areas.The longitudinal strains linearly change along the height of cross section, thus the plane cross-section assumption can beapplied in the composite girder.Moreover, the top concrete flange and the bottom steel concrete pipe chord bear load together.When the cracking load is 140 kN, the calculated and experimental deflection are 5.8 mm and 5.5 mm, respectively, and the relative error is about 5%.When the load of mid-span cross section of test beam reaches the ultimate flexural capacity, the theoretical and experimental load are 399 kN and 415 kN, respectively, the experimental value is slightly higher than the calculated value, but the error is very small and about 4%, so the theoretical calculation methods of deflection and flexural capacity of composite beam are simple and reliable.More>

2016, 16(3): 35-45. doi: 10.19818/j.cnki.1671-1637.2016.03.005

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Influence of connecting cable chain's elastic modulus on energy conversion of flexible floating collision-prevention system

CHEN Xu-jun, YU Wei, LIU Jun-yi

Abstract: In order to study the energy conversion relations in the process of collision between ship and the flexible floating collision-prevention system (FFCPS), the influence of elastic modulus of connecting cable chain on energy dissipation was analyzed.Based on the basic principle of energy conservation, reasonable assumptions were made on the simulation conditions of numerical calculation, and the movement process of flexible floating collision-prevention system was simulated when the system was hit by ship.Under different elastic moduli of connecting cable chain, the changing rules of moving distances of gravity anchors were analyzed.2 kinds of mathematical models were established based on the principle of similarity in displacement and equality in energy, and the numerical calculation results were compared with the experiment results.Analysis result indicates that the elastic moduli of connecting cable chain measure the deformation degree of cable chain, and it is an important influencing factor in the conversion between ship kinetic energy and elastic potential energy.Under the same conditions, the bigger the elastic modulus of connecting cable chain is, the harder the deformation of connecting cable chain is, the less the energy that ship kinetic energy converts into elastic potential energy is, themore the energy that ship kinetic energy converts into friction energy is, and the longer the moving distance of gravity anchor is.Through the comparison between numerical calculation results and experiment results, the suitable value of elastic modulus of connecting cable chain in model test is 260 GPa.To be sure that the connecting cable chain cannot be broken, the selection of cable chain directly affectes the moving distance of system anchor, thus affects the arresting effect of flexible floating collision-prevention system.More>

2016, 16(3): 46-54. doi: 10.19818/j.cnki.1671-1637.2016.03.006

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Effect of system parameters on tread-hollow wear of high-speed train wheels

HUANG Cai-hong, LUO Ren, CENG Jing, SONG Chun-yuan

Abstract: In order to investigate the reasons of tread-hollow wear of high-speed train wheel, a wear prediction model was set up by coupling a vehicle-track system dynamics model to a wear model.In the wheel-rail normal contact, the shape of contact patch and the distribution of normal force were calculated by using Herz's contact theory.In the wheel-rail tangential contact, the tangential force was calculated by using Kalker's simplified theory.The wear loss was calculated by using Achard's wear model.To revise the wear prediction model, the wheel tread wear shape of CRH₃ high-speed train running on Wuhan-Guangzhou Line was simulated, and compared with the wear shape collected from field test.In order to get the wear law close to field test result, the uncertainty of wear coefficient was considered, and the initial wear coefficient should be divided by 10 in wear prediction.Based on the modified theory model, the effects of rail profile, wheelprofile, vehicle speed, track irregularity, line condition, the structure and suspension parameters of bogie on the tread wear law of high-speed train wheel were studied.Analysis result indicates that wheel and rail profiles affect the location, depth, and the width of wheel tread wear, vehicle speed affects the depth of wheel tread wear, track irregularity affects the depth and width of wheel tread wear, and line curve radius affects the depth and width of wheel tread wear.Too high vehicle speed, unreasonable wheel-rail matching relation, and too high track straightness will cause a centered wheel wear, and lead to tread-hollow wear.The suspension and structure parameters of bogie have little impact on tread-hollow wear.More>

2016, 16(3): 55-62. doi: 10.19818/j.cnki.1671-1637.2016.03.007

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Whole-field stress prediction and real-time monitoring of vehicle bogie

TANG Zhao, NIE Yin-yu, WU Ping-bo

Abstract: In order to improve the reliability and accuracy of fatigue strength evaluation and fatigue life prediction, on the basis of the stresses at the predictable positions on the structure, a whole-field stress prediction method was proposed to predict the stresses at the arbitrary positions, a meshless computation-based radial basis function interpolation theory was introduced, a novel selection rule of interpolation domain was built, and the traditional multiquadric (M-Q) radial basis function was refined.In order to verify the interpolation performance of modified M-Q radial basis function, under the condition of exerting 58 kN lateral force, 55 kN longitudinal force and 85 kN vertical force loading on the frame of vehicle bogie, 8 stress unmeasurable positions on the frame were selected, and the interpolation accuracies were compared between the modified M-Q radial basis function and the thin plate spline (TPS) radial basis function.Analysis result shows that the maximal and average relative errors of stress by using the modified M-Q radial basis function are 0.090 6% and 0.028 5% respectively, while the values by using the TPS radial basis function are 1.611 3% and 0.604 2% respectively, so the calculation accuracy of modified M-Q radial basis function is much more better than the value ofTPS radial basis function in predicting the stresses at the unmeasurable positions on the frame of vehicle bogie.Combining with the interpolation algorithm based on the modified M-Q radial basis function, a fatigue strength monitoring system named TPL monitoring for vehicle bogie is developed, and has better interactivity, real-time property and scalability.More>

2016, 16(3): 63-71. doi: 10.19818/j.cnki.1671-1637.2016.03.008

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Design method of holographic optimal sliding mode controller for semi-active suspension of vehicle

CHEN Shi-an, WANG Jun-cheng, YAO Ming

Abstract: To obtain both better comprehensive performance of semi-active suspension under the nominal running condition and the enhanced robustness under the variation parameters/running condition, a design method of holographic optimal sliding mode (HOSM) controller for the semiactive suspension of vehicle was developed.First, when the current optimal sliding mode (COSM) controller was applied, the poorer reasons of the comprehensive performance of semiactive suspension under the nominal running condition and the robustness under the variation parameters/running condition were analyzed.Second, the state equations of control system for the semi-active suspension were augmented, a sliding mode manifold function considering all ofstructural and expected information of suspension was established, and a novel HOSM controller was designed.Finally, based on the numerical simulation, the control result of the proposed controller was compared with the control result of COSM controller and the performance of passive suspension.Analysis result shows that the comprehensive performance of semi-active suspension controlled by the HOSM controller increases by 88.30% and 38.33% compared with the values of the semi-active suspension controlled by the COSM controller and the passive suspension in the nominal running condition; under the variation parameter condition, the maximum fluctuations of comprehensive performance indexes of the suspensions controlled by the HOSM controller and the COSM controller and the passive suspension are 26.22%, 74.42%, and 46.39%, respectively; under the variation running condition, the maximum fluctuations of comprehensive performance indexes of the suspensions controlled by the HOSM controller and the COSM controller and the passive suspension are 78.55%, 106.22%, and 115.06%, respectively.Therefore, using the HOSM controller can not only achieve better comprehensive performance of semi-active suspension under the nominal running condition, but also achieve better robustness compared with the HOSM controller and the passive suspension.More>

2016, 16(3): 72-83. doi: 10.19818/j.cnki.1671-1637.2016.03.009

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Semi-linkage thermal stability of dry clutch under highly accelerated life test

WANG Yang-yang, CHEN Guang-da, LI Nan, YUAN Yi-qing

Abstract: Aiming at the problem of thermal failure of dry clutch during semi-linkage operation, the thermal stability of clutch in semi-linkage process was studied.Based on the sliding friction power of clutch during semi-linkage operation, the key variables effecting the thermal stability were acquired, including the axial pressure of friction plate, relative sliding speed and sliding friction duration time.With the combination of dry clutch thermal model and highly accelerated life test (HALT) method, the enhancement loading profile was designed, and the effect of cyclic enhancement loading test of friction plate thermal model was verified.In order to reflect the influence degrees of different variables on the thermal stability in highly accelerated life test, the effect of sensitive variables on the highest hot spot temperature of friction plate was studied by using orthogonal test and range analysis method.Analysis result indicates that according to the influence degrees from the great to the little, the order of key variables are relative sliding speed, sliding friction duration time and the axial pressure of friction plate respectively.When the engine is running at a lower speed of 1 000 r·min^-1, the hot spot temperature is always under the safe temperature of 200 ℃.When the engine speed exceeds 1 500 r·min^-1, the axial pressure of friction plate is more than 2.0 kN, and the sliding friction duration time is more than 8 s, the hot spot temperature will exceed the safe temperature of 200 ℃. With the right semi-linkage operation, such as controlling both the engine speed and the accumulation time of frequent semilinkage operation, the thermal failure of friction plate can be effectively prevented.More>

2016, 16(3): 84-90. doi: 10.19818/j.cnki.1671-1637.2016.03.010

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Adaptive control of active front steering and direct yaw moment for vehicle

SANG Nan, WEI Min-xiang

Abstract: An integrated control method of active front steering and direct yaw moment for vehicle was proposed based on Lyapunov theory.An adaptive controller was designed based on the vehicle model with two degrees of freedom.The tire stiffness was adaptively estimated to compensate the nonlinear of tire lateral force.The closed-loop simulation model of vehicle was established based on MATLAB and CarSim software.The sinusoidal input simulation test was carried out on road.Simulation result shows that when adhesion coefficient is 0.8 and speed is 100 km·h^-1, the maximum error of front axle lateral force is 210 Nand about 8.1% of front axle actual lateral force, and the maximum error of back axle lateral force is 296 Nand about 8.5% of back axle actual lateral force.When adhesion coefficient is 0.3 and speed is 80 km·h^-1, the maximum error of front axle lateral force is 146 Nand about 8.5% of front axle actual lateral force, and the maximum error of back axle lateral force is 142 Nand about 9.8% of back axle actual lateral force.The integrated control effects of active front steering and direct yaw moment are better than the individually control effects of active front steering and direct yaw moment.More>

2016, 16(3): 91-99. doi: 10.19818/j.cnki.1671-1637.2016.03.011

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Scheduling optimization of tram operation diagram under signal passive priority condition

JIANG Zhi-bin, XU Rui-hua

Abstract: Taking rail transit line with semi-closed road right and shared road right as background, based on intersection signal passive priority controlling strategy, under the condition of given signal periods for different intersections and green light durations, the definition rule of intersection topology structure and the expression method of intersection operation diagram were studied. An integer programming model of tram timetable and intersection green light signal timing optimization was built in order to increase tram travel speed.A section of tram line in one city was taken as an example to verify the model by using timetable scheduling software.Calculation result shows that when the green light duration is 15 s, the added value of travel time is 341 swithout green light signal timing optimization, the added value of travel time is only 56 safter optimization, which saves 285 s.Green light signal timing optimization has obvious effect on increasing the travel speed of tram train.Tram operation diagram with best comprehensive travel time can be drawn up based on the calculation result of the model.More>

2016, 16(3): 100-107. doi: 10.19818/j.cnki.1671-1637.2016.03.012

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Numerical simulation research on air quality of aircraft cabin

DAI Bing-rong, LIU Yi-guo, YU Gang, SI Hai-qing

Abstract: B737NG cabin model was taken as object, and CFD method was used under the working condition of no passenger to analyze the distributions of air velocity, temperature, formaldehyde concentration and carbon dioxide concentration in aircraft cabin under four kinds of air supply modes, named ceiling air supply mode, luggage rack air supply mode, ceiling and luggage rack air supply mode, and ceiling and personal air supply port air supply mode.Research result shows that under the third and fourth air supply modes, the distributions of air velocity in cabin are uniform, and air velocity near to passenger seat is about 0.2 m·s^-1.Under the fourth air supply mode, the distribution of temperature in cabin is most uniform, and the temperature increases gradually to 296 K from air supply port to passenger seat.Under the third and fourth air supply modes, the formaldehyde concentration in cabin is lower.Under four air supply modes, the carbon dioxide concentration in cabin is in the standard range.Among four kinds of air supply modes, ceiling and personal air supply port air supply mode can make the distributions of air velocity and temperature more uniform, remove air pollutants more effectively, and provide better air quality.More>

2016, 16(3): 108-115. doi: 10.19818/j.cnki.1671-1637.2016.03.013

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Influence of irregular disturbance of sea wave on ship motion

QIAN Xiao-bin, YIN Yong, ZHANG Xiu-feng, LI Ye

Abstract: Aiming at the demand of high-precision motion mathematical model with six degrees of freedom for dynamic positioning ship, the modeling method of irregular wave disturbance and its influence on ship motion were studied, and the shape, forces and moments of short-crested waves and long-crested waves were compared.Based on Froude-Krylov hypothesis, the ship was regarded as a box type ship, and the time-domain models of long-crested and short-crested irregular wave disturbance were built.Base on slight wave hypothesis and linear superposition principle, the three-dimensional models of long-crested and short-crested irregular waves were built by using Chinese coastal frequency spectra and the spreading function recommended by International Towing Tank Conference (ITTC).The simulation for a dynamic positioning ship was carried out with main wave direction angles of 90°, 135°and 180°respectively.Simulation result shows that the first-order wave forces generated by long-crested and short-crested waves show high frequency vibration changes.When main wave direction angle is 90°, the first-order wave surge force, roll moment and pitch moment of long-crested wave are close to zero.When main wave direction angle is 180°, the first-order wave sway force, yaw moment and pitch moment of long-crested wave are close to zero.The second-order forces and moments of long-crested wave are larger 19.2% than those of short-crested waves.The short-crested waves are more irregular and asymmetry than long-crested waves in shape, and the short-crested irregular waves can have greater impact on ship motion in wave.More>

2016, 16(3): 116-124. doi: 10.19818/j.cnki.1671-1637.2016.03.014

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Bi-level programming model of traffic microcirculation optimization for historic district

WANG Qiu-ping, DING Meng

Abstract: In order to fulfill the increasing traffic demand of historic district, rich streets and alleys in the district were used to organize traffic microcirculation, and a bi-level programming model of traffic microcirculation optimization for historic district was built.The up-level model was built targeting on increasing the transit efficiency of trunk roads, increasing the average travel speed of road network, deceasing bypass time and controlling environmental pollution in the constraint conditions district unblocking and historical relics protection of streets and alleys.User equilibrium traffic assignment was used to solve the down-level model by using TransCAD.The historic district of Caoshi Street in Kaifeng was taken as an example to carry out case analysis.Calculation result shows that optimization calculation makes the average saturation of trunk road decease from 0.69 to 0.36 at most, the average travel speed of road network increase from 26.33 km·h^-1 to 28.87 km·h^-1 at most, the average saturation of streets and alleys in the district increase from 0.07 to 0.37 at most, and bypass time and environmental pollution are controlled.Obviously, the model application relieves the traffic pressure of trunk road network and improves district accessibility and overall operating efficiency, which has good traffic benefit and environmental benefit.More>

2016, 16(3): 125-132. doi: 10.19818/j.cnki.1671-1637.2016.03.015

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Flow-density relationship of mixed bicycles based on Logistic model

ZHOU Dan, MA Xiao-long, JIN Sheng, WANG Dian-hai

Abstract: Aiming at the traffic phenomena of electric bicycle and traditional bicycle mixed driving on non-motorized road, logistic model was introduced based on the analysis of mixed bicycles'flow characteristic, the numerical analysis method was used to build the mathematical model, to suitably describe the flow-density relationship of mixed bicycles, and the calculation model of bicycle lanes'traffic capacity was proposed.The data fitting was carried out based on the field data of six road sections in Hangzhou, the estimation values of traffic capacity were obtained, and the parameter sensitivity analysis was carried out for the maximal speed in bicycle flow samples, the speed of freedom flow and the optimal density.Research result shows that the fitting goodnesses of the data of six road sections are 0.92, 0.93, 0.93, 0.95, 0.98 and 0.96 respectively, and traffic capacities are 2 968, 2 641, 2 687, 2 754, 2 646 and 3 065 bic·(h·m)^-1respectively, so this model can well describe change the characteristics of urban mixed bicycle flow in different states, and it provides a new way to further uncover the operation mechanism of mixed bicycle flow in urban bicycle lane.More>

2016, 16(3): 133-141. doi: 10.19818/j.cnki.1671-1637.2016.03.016

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Delay comparison between through-left lane and left turn lane for at-grade intersection with permitted left turn control

SHAO Hai-peng, LU Ji-na, DONG Hai-qian

Abstract: In order to compare the delays of exclusive left turn lane and through-left shared lane in permitted left turn phase, the operation laws of traffic flow under two left turn traffic organization modes were analyzed.Based on the gap acceptance theory, the arrival rate and the left turn vehicle percentage were taken as variables to build the delay models for two left turn traffic organization modes with Poisson arrival londition respectively.The geometric design and signal control data of a intersection in Xi'an were taken as example to analyze the delays.Calculation result shows that total delays increase with the increase of arrival rate and left turn vehicle percentage.When arrival rate is smaller, the delay with exclusive left turn lane is larger.The delay with through-left shared lane gradually approaches or even overtakes the delay with exclusive left turn lane with the increase of arrival rate.Through-left shared lane is suitable for smaller traffic demand, and exclusive left turn lane is suitable for larger traffic demand.When arrival rate is no more than 0.12 pcu·s^-1, or arrival rate is 0.12-0.18 pcu·s^-1 and left turnvehicle percentage is no more than 0.2, through-left shared lane layout is recommended.When arrival rate is no less than 0.18 pcu·s^-1, or arrival rate is 0.12-0.18 pcu·s^-1 and left turn vehicle percentage is more than 0.2, exclusive left turn lane layout is recommended.More>

2016, 16(3): 142-148. doi: 10.19818/j.cnki.1671-1637.2016.03.017

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Algorithm design and implementation for a real-time lane departure pre-warning system

XU Mei-hua, ZHANG Kai-xin, JIANG Zhou-long

Abstract: Aiming at the real-time lane departure pre-warning question, a lateral erosion operator was used to corrode the image after edge detection, and the irrelevant edge information in image was reduced and eliminated to decrease the follow-up processing data quantity significantly.A threshold selection method of edge gradient image block based on Otsu algorithm was proposed to effectively partition road edge image under asymmetrical illumination.A lane line voting selection and scoring algorithm combining the geometrical characteristics of lane line distribution on road, Hough voting results, the correlation of road images and the width characteristics of lane line was proposed to recognize the lane line in multilane scenes.Kalman filter method was applied to track the lane line.The algorithm software of lane departure pre-warning system was used to carry out the test verification.Test result shows that total frame number of road images is 24 661, the frame number of right detection is 23 483, and the frame number of wrong detection is 1 178, and the average detection accuracy is 95.22%.The test verified the correctness and effectiveness of the algorithm, which can satisfy the real-time feature and robustness of lane departure prewarning system.More>

2016, 16(3): 149-158. doi: 10.19818/j.cnki.1671-1637.2016.03.018

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