交通运输工程学报

Establishment and finite element mesh of 3D mesoscopic stochastic models of concrete

HU Da-lin, ZHANG Li-xing, CHEN Ding-shi

Abstract: The concrete was assumed to be a two-phase composite material of aggregate and mortar.The mathematical boundary conditions and interference judgment of spherical and ellipsoid aggregates and their mixtures were studied, respectively.A stochastic packing algorithm was designed for the spherical and ellipsoid aggregate, and a corresponding program was compiled using MATLAB to realize the generation of a three-dimensional mesoscopic stochastic geometric model of concrete.The interference relationship of spherical aggregates was judged by the center distance between adjacent aggregate particles.The interference between ellipsoidal aggregates was judged by the relationship between any point on an ellipsoid and a point on the straight-line segment formed by the connection of any point on an ellipsoid and the center of another ellipsoid.Thus, the interference relationship between two ellipsoids was simplified as the relationshipbetween an ellipsoid and a point.A program named mat2 scr 2017 was developed on MATLAB to read the graphic file data from MATLAB into SCR script file.The stochastic aggregate model built with mat2 scr 2017 program was transformed into an AutoCAD graphics file and input into the COMSOL Multiphysics software.The finite element mesh of concrete geometric model was carried out through COMSOL Multiphysics.Research result shows that the volume ratio of the stochastic aggregate model can reach 50%, and the aggregate size and packed position meet the randomness requirements.The ellipsoid random aggregate packing algorithm is simple and efficient, and can guarantee the randomness of dip angle of ellipsoid.The model is applicable to the generation of arbitrarily graded concrete, and the continuously graded concrete aggregates are packed according to different gradations, thus ensuring the volume ratio of the aggregates at all levels.The conversion of MATLAB graphics to AutoCAD graphics is realized, and the generality of stochastic concrete model is greatly enhanced.The mesh generation of the concrete model meets the requirement of grid consistency at the interface of aggregate and mortar, and the needs for finite element analysis.More>

2018, 18(5): 1-11. doi: 10.19818/j.cnki.1671-1637.2018.05.001

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Influence of unbalanced pavement friction on landing taxiing parameters of aircraft

CAI Jing, ZHANG Heng, LI Yue, SUN Rui-qiang

Abstract: A mechanical model of aircraft landing taxiing was established based on the kinematics principle, and the unbalanced pavement friction degree was introduced.On the basis of the in-situ measured pavement friction coefficient and unbalanced friction degree, the variation tendencies of an aircraft's yaw angle and yaw distance during its landing deceleration and taxiing at constant speed were analyzed.The model tests were conducted, and the variation tendencies of landing taxiing parameters under unbalanced pavement friction of a wet runway were analyzed.Analysis result indicates that the unbalanced runway friction at two sides of a runway centerline leads to the aircraft turning around the vertical axis, which leads to the incurrence of yaw angle and yaw distance during aircraft landing taxiing.Increasing unbalanced pavement friction degree causes an increase in yaw angle and yaw distance during aircraft landing taxiing.When the unbalanced friction degree increases from 0.03 to 0.38, the yaw angle increases by 4 times, and the yawdistance increases by 1 time.Therefore, decreasing unbalanced friction degree at two sides of a runway centerline can effectively reduce the probability of an aircraft's runway deviation in landing taxiing.The slip ratio of tires on the aircraft has little influence on yaw angle and distance of the aircraft.When the pavement friction coefficient decreases, the taxiing distance of deceleration increases linearly.With the increase of unbalanced friction degree on the runway's landing strip, the yaw angle increases linearly.As the unbalanced friction degree reaches 0.165, the yaw angle is 1.2°.With the increases of unbalanced friction degree on the runway's landing strip, the yaw distance also increases.For the yaw angle occurring in deceleration taxiing and a long uniform velocity taxiing distance, above 70% yaw distance in landing taxiing occurrs in the uniform section.When the water film thickness difference on the two sides of wet runway center line increases, the yaw angle and yaw distance during the aircraft's landing taxiing increase as well, and as the water film thickness difference increases from 0.05 mm to 2.50 mm, the yaw angle increases by 6 times, and the yaw distance increases by 5 times.Therefore, the balance of friction at the position of the aircraft's main landing gear on the landing strip should be guaranteed, because it is beneficial to the yaw angle control during an aircraft's deceleration section.More>

2018, 18(5): 12-24. doi: 10.19818/j.cnki.1671-1637.2018.05.002

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Fatigue assessment of floorbeam cutout in orthotropic steel bridge deck based on hot-spot stress method

ZHU Zhi-wen, HUANG Yan, LI Jian-peng, RUAN Shi-peng

Abstract: Based on finite element analysis and stress monitoring data at fatigue details under random traffic flows, stress time histories for an area close to a floorbeam cutout of orthotropic steel bridge deck were obtained to analyze the peak stress distribution.Fatigue assessment at a floorbeam cutout was carried out based on the hot-spot stress obtained through the extrapolation formulas specified by the International Institute of Welding and the Det Norske Veritas, respectively.Suitable extrapolation formulas for hot-spot stress at floorbeam cutout were also investigated.Research result shows that under the passage of vehicles on deck, stress responses at floorbeam cutout are compressive, and the peak stress is high. A significant stressconcentration occurs at the free edge of floorbeam cutout, and an obviously nonlinear stress distribution appears in a small range along the critical section of floorbeam cutout.When using the hot-spot extrapolation formulas provided by the International Institute of Welding and the Det Norske Veritas, the hot-spot stress is overestimated and the estimated fatigue life is conservative due to their stress extrapolation points falling into the nonlinear distribution zone.All the stress extrapolation points of the proposed two-point linear extrapolation formula and three-point quadratic extrapolation formula are located on the linear distribution zone of the construction details stress.The first extrapolation point is located on one thickness of floorbeam away from the free edge of the cutout.The fatigue life at floorbeam cutout evaluated by this method agrees well with the observed cracking life of floorbeam cutout on a real bridge.When the hot-spot stress is employed to evaluate the fatigue life of floorbeam cutout of orthotropic steel bridge deck, the fatigue category of FAT90 and the proposed three points quadratic extrapolation formula are suggested.More>

2018, 18(5): 25-34. doi: 10.19818/j.cnki.1671-1637.2018.05.003

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Parametric analysis on seismic behavior of integral abutment steel bridge considering SSI

ZHAO Qiu-hong, QI Chao-yang, AN Ze-yu, CHEN Bao-chun

Abstract: A 3D finite element model of integral abutment steel bridge was established by the SAP2000 software, the nonlinear spring elements and damping elements were used to simulate the soil reactions behind the abutment and around the piles under the earthquake action, and the mode, nonlinear time history and relevant parameters of the bridge were analyzed, In addition, the dynamic and seismic behaviors of integral abutment steel bridge considering the nonlinear soilstructure interaction, as well as the influence of the main design parameters of integrated abutment system on the behaviors were studied.Research result indicates that compacting the abutment backfill, increasing the abutment height-to-thickness ratio, and increasing the foundation stiffness will increase the dominant longitudinal frequency of the bridge structure byabout 6.5%-16.0%, while H pile orientation has a minimal influence of about 1.6%.The structural seismic response significantly reduces as the abutment height-thickness ratio increases.When the abutment height-to-thickness ratio is 1.44, the top of the pile enters the plastic stage.When the height-to-thickness ratio increases to 3.15 and 3.85, the pile remains elastic.When the compactness of the abutment backfill decreases, the seismic response of the structure increases significantly, and the increment is mostly above 40%.When the orientation of the pile is adjusted from bending about the strong axis to bending about the weak axis, the maximum bending moment of the pile decreases, but the bending stress increases, and the material enters the plastic stage from the elastic stage.As the soil stiffness around the pile increases, the displacement response of the bridge decreases significantly.The maximum displacements at the top of the pile and abutment, as well as the bending moment at the pier bottom decrease by about 50%.However, the bending moment at the pile top increases by more than 40%, and the orientation of the pile has almost no effect on the displacement responses.As long as the design requirements are satisfied and in a reasonable range, the larger height-to-thickness ratio, more flexible abutment, and compacted abutment backfilling are recommended to reduce the seismic response of integral abutment bridge.When the steel H pile is used as the abutment foundation, orienting the H pile to bend about its strong axis is recommended to reduce the maximum bending stresses and displacements of the pile, abutment and pier.More>

2018, 18(5): 35-46. doi: 10.19818/j.cnki.1671-1637.2018.05.004

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Extrapolating method of extreme load effects on long-span bridge under actual traffic loads

LU Nai-wei, LIU Yang, XIAO Xin-hui

Abstract: A probabilistic superposition approach was proposed for investigating the extreme load effects of stochastic traffic flows with multiple densities.The approach was utilized to extrapolate the extreme values of vehicle load effects on the long-span bridges using the measured traffic data.The principle of superposing level-crossing rate based on the Rice's formula was explained, and its validity was proved.Three types of stochastic traffic flows, including the sparse flow, normal flow and dense flow, were simulated based on the long-term monitored traffic data of a highway bridge in China, and the maximum bending moment of a concrete cable-stayed bridge was analyzed based on the level-crossing superposition model.Analysis result shows that basedon the measured traffic data of a highway, the densities of free flow, normal flow and busy flow are 1.7, 5.0 and 8.3 veh·min-1, respectively.In the numerical example, when the occupancy of 45 t-vehicles increases from 0 to 80%, the maximum vehicle mass decreases by only 1.2%.But when the occupancy of 50 t-vehicles increases from 0 to 20%, the maximum vehicle mass decreases by 14.4%.This phenomenon indicates that the extreme value of a non-equilibrium random process composed by some stationary random processes is mostly depended on the random processes with higher values.The maximum extrapolating error of the maximum vehicle mass is2.55%for the mixed traffic flow using the level-crossing superposition approach, which explains that the extrapolating approach of extreme load effects on long-span bridges based on the principle of vehicle dispersion and superposition of extreme value probability is feasible.The increase of occupancy of dense traffic flow from 0 to 5%leads to an amplification of 33.45%for the maximum bending moment of the girder of a cable-stayed bridge.When the annual traffic growth rate of a cable-stayed bridge is 2.8%in the design lifetime, the probability that the midspan extreme bending moment of the bridge girder exceeds the design standard value is 0.83 and higher than the design requirements, therefore, it is deserved to take some measures to control the traffic flow.More>

2018, 18(5): 47-55. doi: 10.19818/j.cnki.1671-1637.2018.05.005

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Flexural behavior experiment of full-scale PC box girder strengthened by composite technique

WANG Shi-chao, WANG Chun-sheng, DUAN Lan, SHEN Jian-cheng, WANG Qian

Abstract: In order to solve the problem of declining structural performance of old concrete girder bridges, a full-scale test was conducted to investigate the flexural behavior of small PC box girders strengthened by the steel plate-concrete composite strengthening (SPCCS) technology.Two full-scale 20 m-span small PC box girders strengthened by the SPCCS technique were tested to research their bending properties, the test result was compared with the full-scale test results of an unstrengthened girder and a prestressed CFRP (carbon fiber reinforce plastic) strengthened girder, the flexural behavior of full-scale SPCCS box girders was analyzed, and the straindistributions of strengthening steel plates, major reinforcements of original girder, concrete and reinforcements at the top flange, and connection sturctures at the mid-span section in the whole loading process were studied.Based on the full-scale test results, the simplified calculation formulas of flexural capacity of SPCCS full-scale small PC box girder was established.Research result shows that the SPCCS girders fail in the plastic flexural mode.Compared with the unstrengthened girder, the measured ultimate flexural capacity of SPCCS full-scale test beam increases by more than 76%, and the stiffness in normal usage stage increases by more than1 time, therefore, the composite strengthening can obviously improve the flexural capacity of PC box girder.The strain distribution of mid-span section for test girder is in accordance with the plane cross-section assumption.The longitudinal relative slip between the composite strengthened part and the web of concrete box girder is less than 0.6 mm, therefore, the SPCCS girder has good integral working performance.The ratios of the measured and calculated ultimate flexural capacities of 2 full-scale test girders are 1.06 and 1.01, respectively, so the simplified formulas are reliable and can be used to calculate and analyze the bearing capacity of PC box girder strengthened by the composite strengthening.More>

2018, 18(5): 56-65. doi: 10.19818/j.cnki.1671-1637.2018.05.006

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Mechanical performance of jointless retrofitted bridge with hollow-slabs

XU Zhen, CHEN Bao-chun, HUANG Fu-yun, ZHUANG Yi-zhou, HUANG Qing-wei

Abstract: A multi-span bridge with hollow-slabs was retrofitted into a jointless bridge, in which the simple support slabs were converted into the continuous slabs with double row supports and the general abutments were converted into deck-extension abutments, thus, all movable deck joints of the bridge were eliminated.The static and dynamic load tests of jointless retrofitted bridge with multi-span hollow-slabs were carried out, and the mechanical performance of the bridge was studied.The finite element model was used to calculate the structural mechanical performance, bearing capacity and mechanical performance of approach slab, and to analyze the influence of single and double rows supports on the structural mechanical performance.Test result shows that after jointless retrofitting, the tested fundamental frequency of the bridge is8.60 Hz and larger than 5.37 Hz before jointless retrofitting.The maximum tested impact factor is 1.11 of four vehicle speeds and smaller than 1.36 that is the calculated value by the General Specifications for Design of Highway Bridges and Culverts (JTG D60—2004).The verification coefficients of the strain and deflection are less than 0.95.Obviously, the jointless retrofitting enhances the integrality of the bridge and improves the driving comfortability.The finite element analysis result shows that after jointless retrofitting, the fundamental frequency of the bridge is8.48 Hz, and the ratio is 1.01 between the tested fundamental frequency and calculated result, so the bridge is in good working condition.The positive bending moments of mid-span sections reduce significantly with a maximum value of 15.6% at the second span, while the negative bending moments appear at the inner-supports and the shear forces near the inner-supports increase with a maximum value of 18.2%.The mid-span deflections decrease obviously with a maximum value of 35.5% at the second and third spans, which indicates that the integral stiffness of the bridge improves significantly.The calculated maximum crack width is 0.15 mm and smaller than 0.20 mm that is the allowable value in the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62—2004) (Bridge Code for short), and the checking results of bearing capacity, deflection and crack width meet the requirement of Bridge Code.The rows of supports have no significant effect on the inner forces of the superstructure, and the double row supports are feasible.The friction coefficient between the approach slab and its subgrade has significant influence on the axial forces of the approach slabs and the pavement, but has no significant effect on the bending moment.The maximum tensile stresses of the approach slab and pavement are 0.87 and 1.25 MPa, respectively, which meets the strength design requirement.More>

2018, 18(5): 66-76. doi: 10.19818/j.cnki.1671-1637.2018.05.007

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Calculation method of restoring force model of four-element variable cross-sectional concrete filled steel tubular laced column

OU Zhi-jing, CHEN Sheng-fu, WU Qing-xiong, YUAN Hui-hui

Abstract: The finite element analysis method of seismic performance of four-element variable cross-sectional concrete-filled steel tubular (CFST) laced column was put forward.The specimens were modeled and analyzed by the OpenSEES general program, and the load-displacement hysteretic curves and horizontal peak loads of laced columns were computed.The influence rules of longitudinal slope, axial compression ratio, slenderness ratio, area ratio of lacing tubes to longitudinal tubes, yield strength of steel, concrete strength, arrangement type of lacing tubes, and other extension parameters on the skeleton curves of variable cross-sectional CFST laced columns with flat or inclined tubes were investigated.According to the calculation frame of skeleton curves of equal sectional CFST laced columns, the calculation formulas of skeleton curves characteristic values (including the elastic stiffness, horizontal peak load and its displacement, and fall-period stiffness) of four-element variable cross-sectional CFST laced columns were obtained by the equivalent length method.The calculation formula of restoringforce model was deduced resorting to the calculation model of skeleton curve and verified by the engineering example.Research result indicates that the axial compression ratio, slenderness ratio, longitudinal slope, area ratio of lacing tube to longitudinal tube, and material parameters are the main influence parameters on the seismic performance of variable cross-sectional CFST laced columns, the common influence rules are the same as the rules on the equal section laced column, and the numerical difference is within 20%.The calculated results of characteristic values of each specimen are in good agreement with the finite element analysis results, and their ratios are 0.990-1.029, the mean square errors are 0.105-0.153, and the errors are basically controlled within 15%.The errors to calculate the restoring force model of four-element variable cross-sectional CFST laced columns are within 12%, so the computation result is reliable.More>

2018, 18(5): 77-89. doi: 10.19818/j.cnki.1671-1637.2018.05.008

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Effect of track comprehensive maintenance on geometry irregularity improvement of ballast track in high-speed railway

MU Dong-sheng, ZHOU Yu, HAN Yan-bin, ZHENG Xiao-feng, KUANG Di-feng

Abstract: According to the track geometry inspection data captured before and after comprehensive maintenance of ballast track in a high-speed railway, the improvements in the geometric irregularity of comprehensive maintenance that consists of large machinery work, artificial fine adjustment, and rail grinding were analyzed.Analyses result shows that the large machinery work, artificial fine adjustment, and rail grinding can improve track geometric irregularity effectively.Among them, the improvement rates of large machinery work on track vertical, cross, and twist irregularities are 20.95%, 12.90%, and 13.16%, respectively, the improvement rates of artificial fine adjustment on track vertical, cross, twist, and gaugeirregularities are 11.97%, 5.56%, 7.43%, and 6.12%, respectively, and the rail grinding can improve the track vertical and alignment irregularities by 4.85% and 3.88%, respectively.The track quality index (TQI) improves by 11.54%, 6.91%, and 1.10%after large machinery work, artificial fine adjustment, and rail grinding, respectively.Large machinery work and artificial fine adjustment have obvious effects on the improvement of single irregularities.The contribution of large machinery work is the largest, whereas the artificial fine adjustment can improve the track gauge irregularity to a certain extent, and the rail grinding can further improve the track vertical irregularity and track alignment irregularity, but have no obvious effects on the track cross irregularity, track gauge irregularity, or track twist irregularity.Through the comprehensive maintenance, the single irregularity and TQI both decrease, in which the TQI, track vertical irregularity, track cross irregularity, and right track alignment irregularity decrease approximately as power functions, the left track alignment irregularity decreases approximately as a linear function, and the track twist irregularity decreases approximately as a logarithmic function.The geometrical state of the track irregularities improves effectively after large machinery work, and the artificial fine adjustment and rail grinding can further improve some single irregularities.More>

2018, 18(5): 90-99. doi: 10.19818/j.cnki.1671-1637.2018.05.009

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Dynamic optimization design of hanging parameters for traction transformer of high-speed train

HE Xiao-long, ZHANG Li-min, ZHANG Fu-bing, LUO Tian-hong

Abstract: A vehicle-equipment rigid-flexible coupling system model with 21 degrees of freedom was proposed in order to optimize the hanging parameters of traction transformer.The new and rapid explicit numerical integration method was used to compute the vibration response of the vehicle and traction transformer.The vehicle comfort degree indexes and equipment vibration severities of vehicle system under different speeds were calculated, and the optimal hanging frequency of the transformer was obtained.A mathematical model of the transformer and a rigidflexible coupling model of vehicle-equipment were set up, the multi-object dynamic optimization was performed on the vibration isolator parameters under considering the optimal hanging frequency, vibration severity, comfort degree index, dynamic force of vibration isolator, and matching index of transformer suspension mode and vehicle floor local mode, and the optimalparameters of vibration isolator in the transformer were computed.Research result indicates that when the suspension frequency ratio of the traction transformer is 0.82-0.92, the vehicle comfort degree index is less than 2, and the vibration severity of the equipment is less than 4.5 mm·s-1, which can satisfy the requirements of related standards.After optimization, the vertical stiffness of the first group isolator, the stiffness ratio of three groups of isolators and the three directions' s stiffness ratio of each group of isolators are 2 142 N·mm-1, 1∶1.3∶2.5 and 1.7∶0.5∶1, respectively.Compared with the original suspension scheme of the transformer, the vibration severity of equipment decreases by up to 42%at the speed more than 200 km·h-1, the comfort degree indexes of front, middle and rear vehicle respectively increase by 3.53%, 3.45% and2.01% on average, the vertical forces of the isolators 1 and 4 decrease by 13.3%on average, the vertical forces of the isolators 2 and 5 decrease by 3.8%, and the vertical forces of the isolators 3 and 6 decrease by 20.9%.Thus it can be seen the comfort degree index of vehicle, vibration severity of equipment and vertical dynamic force of vibration isolator improve after optimization.More>

2018, 18(5): 100-110. doi: 10.19818/j.cnki.1671-1637.2018.05.010

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Suspension stiffness selecting method of elastic suspension equipment under vehicle

ZHU Tao, LEI Cheng, XIAO Shou-ne, YU Jin-peng

Abstract: Taking the low-order elastic vibration, the rigid body vibration and the equipment active vibration of carbody as inputs, a method for rapidly and simply determining the suspension stiffness of elastic equipment was proposed.Under the premise of fully considering the coupling vibration that may occur in all directions, equipment installation clearance, the maximum allowable vibration displacement of suspension equipment and other factors, the formula for calculating the rigid body vibration frequency of suspended equipment with arbitrary suspension method was derived.The selection method and analysis process of suspension stiffness of elastic suspension equipment under vehicle were given.Taking a certain electric multiple unit (EMU) as an example, the coupled vibration analysis model of carbody and power pack was established.The ranges of rigid body vibration frequencies of nodding, shaking, floating and sinking, lateralrolling, and three-dimensional suspension stiffnesses of power pack were calculated, and the theoretical calculation results of suspension stiffness of power pack were compared with corresponding finite element results.Research result shows that under the premise that the basic parameters of carbody or suspension equipment are known, the proposed method can calculate the rigid body vibration frequencies of nodding, shaking, floating and sinking, and lateral rolling, without complicated dynamic modeling and analysis. Comparing with the finite element calculation result, the maximum relative error in rigid body vibration frequency is 6.88%.All the calculated frequency ratios between rigid body vibration frequencies of power pack and corresponding vibration frequencies of carbody can effectively avoid the coupling interval[0.750, 1.414].Therefore, the stiffness of elastic suspension equipment under vehicle calculated by the proposed method can quickly and accurately determine the stiffness rang of suspension equipment, so as to avoid the resonance between equipment and carbody.More>

2018, 18(5): 111-118. doi: 10.19818/j.cnki.1671-1637.2018.05.011

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Sliding mode control for ship dynamic positioning based on linear matrix inequality

XUE Han, SHAO Zhe-ping, PAN Jia-cai, FANG Qiong-lin

Abstract: In order to solve the control problem of ship dynamic positioning systems with nonlinear and environmental disturbances, a sliding mode control algorithm based on the linear matrix inequality (LMI) was proposed.The tracking error was designed as a sliding mode function, and a linear matrix inequality was designed to solve the state feedback gain.Based on the quadratic Lyapunov function, the stability of the closed-loop system was proved.The switching function was designed to make the system robust to uncertainties and external disturbances and to avoid chattering.The sliding mode controller based on the LMI was simulated, and the forward speed, sway speed, heading angular speed, forward acceleration, sway acceleration, heading angular acceleration, forward control force, sway control force, and heading control moment of a dynamic-positioning ship were calculated under two different conditions, namely, uniform motion without disturbance and variable-speed motion with external environment disturbance.The effects of parameters such as the linear matrix of state feedbackgain, boundary layer, and switching gain on control performance were analyzed and compared.Analysis result indicates that it takes 29 sfor the forward speed to reach the expected value by using the basic sliding mode control, whereas the new algorithm saves 48.28% at 15 s.It takes24 sfor the sway speed to reach the expected value by using the basic sliding mode control, whereas the new algorithm saves 41.67%at 14 s.It takes 13 sfor the heading angular speed to reach the expected value by using the basic sliding mode control, whereas the new algorithm saves 23.08%at 10 s.Thus, the designed controller has strong robustness for the ship dynamic positioning system with nonlinear and environmental disturbances, and has the characteristics of continuous control input, no control chattering, and no high gain.More>

2018, 18(5): 119-129. doi: 10.19818/j.cnki.1671-1637.2018.05.012

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Game control of multi-agent damper system for laterally interconnected air suspension

LI Zhong-xing, TANG Wei, HUANG Jian-yu, LU Ying

Abstract: To further improve the ride comfort and handling stability of vehicles equipped with laterally interconnected air suspension (LIAS), on the basis of multi-agent theory and the cooperative game Shapley value principle, a multi-agent damper control system was constructed.The multi-agent vibration absorber control system was composed of an information publishing agent, ride comfort agent, handling stability agent, and game cooperation agent.The vehicle state information from the environment was obtained by the information publishing agent, and the information transmission was finished according to the information demand of the lower agent.The suspension dynamic travel and its changing rate information were received by the ride comfort agent, and its own damping coefficient intention was output according to the ride control requirements.The information of the current interconnected state was received by the handlingstability agent, the corresponding reasoning module was triggered, and the required damping coefficient was solved according to the information of the carbody roll angle.The reasoning module was formed by fuzzy neural network self-learning to the damping coefficient optimized by agenetic algorithm.The damping intents of the ride comfort agent and handling stability agent were received by the game cooperation agent, the damping intents were modified according to its own cooperative game rules, and the global optimal damping coefficient was outputted.Under different interconnected states and different excitation conditions, the static and dynamic characteristics of the air suspension were tested and compared with the simulation results, and the accuracy of the simulation model was verified.Under the condition of mixed construction, the feasibility and effectiveness of the multi-agent damper control system were verified by a vehicle simulation model.Analysis result shows that compared with the traditional damping control system, the multi-agent damper control system can effectively reduce the RMS values of the sprung mass acceleration, the suspension dynamic travel and the body roll angle by 14.95%, 10.64%and 12.33%, respectively.Therefore, the proposed system not only improves the ride stationarity and comfort, but also restrains the car's side inclination and improves the handling stability of the whole vehicle.More>

2018, 18(5): 130-139. doi: 10.19818/j.cnki.1671-1637.2018.05.013

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Multi-mass trammel pendulum model of fluid lateral sloshing for tank vehicle

YANG Xiu-jian, XING Yun-xiang, WU Xiang-ji, ZHANG Kun

Abstract: To deeply investigate the lateral dynamics of tank vehicle, the equivalent mechanical model of fluid lateral sloshing for a tank with elliptical (circular) sectional shape was studied.The predicting precision of the trammel pendulum (TP) model was evaluated by the computational fluid dynamics (CFD) software FLUENT, and the effects of fill level, tank sectional ellipticity, and excitation frequency on the model's predicting precision were analyzed.A generalized multi-mass TP model was proposed, the mass and distance between each part of fluid pendulum were reasonably distributed to adapt to the variations in tank sectional ellipticity and fill level.The dynamics equation for the generalized multi-mass TP model was derived based on the Lagrange approach.The method to determine the parameters of mass ratio and distance between the two masses, and the fitting formulas of double mass TP (DMTP) model were presented.The predicting precision of theproposed DMTP model was evaluated by the CFD method.Analysis result shows that the sloshing moment gained from the TP model is generally less than that computed by the CFD method, and the predicting error generally increases as the fill level increases.The predicting error of the peak sloshing moment increases from 15%to 65% when the fill level increases from 30%to 80%.This is mainly because the TP model is fitted under the conditions of small initial fluid incline angle and free sloshing.When the fill level and sloshing frequency are relatively high, both the length of pendulum arm and the sloshing fluid mass are less than the actual cases.The proposed DMTP model presents a relatively stable and high predicting precision in most conditions of fill levels, tank sectional ellipticities and excitation frequencies.Comparing with the TP model, when excitation frequency is 0.2 and 0.3 Hz, respectively, the mean value of the root mean square error (RMSE) of the predicted maximum sloshing moment in the DMTP model decreases by 54.2% and 43.9%, respectively, and the standard deviation decreases by 45.1% and 31.2%, respectively.The predicting precision of the proposed DMTP model is obviously higher than that of the TP model, and the DMTP model can especially well make up for the deficiency of low predicting precision of the TP model in the case of high fill level.More>

2018, 18(5): 140-151. doi: 10.19818/j.cnki.1671-1637.2018.05.014

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Ship scheduling optimization on bulk cargo port considering ship lightening and berth shifting

ZHENG Hong-xing, LIU Bao-li, ZHANG Run, WANG Cui-ping

Abstract: To improve the service level of bulk cargo port and make full use of its existing berth resource, the ship scheduling optimization on bulk cargo ports using ship lightening and berth shifting strategies was studied.The impact of large ship lightening and berth shifting on ship scheduling in a bulk cargo port was considered, ship inbound/outbound order, berth shifting order and berth shifting position were taken as decision variables, the minimum waiting time of inbound and outbound ships was taken as the objective function, a mixed integer linear programming model was constructed.Based on the characteristics of the model, a hybrid algorithm and heuristic rules for generating an initial population were given.A neighborhood strategy for constructing a new population was proposed, and the effective improvement measures in the simulated annealing algorithm were introduced.To verify the effectiveness of this scheme and the algorithm, the comparison tests for the scheme and algorithm based on actual research data were given, and the influences of ship tidal ratio and length of inbound/outbound period onthe optimization results of the scheme were analyzed.Research result shows that comparing with the two current ship scheduling schemes with the first-come first-served idea and greedy strategy, the average optimization rates of the two proposed schemes are 11.07% and 9.84%, respectively.When the fleet size increases from 20 to 50, the calculation time of the hybrid algorithm always be less than 2 min, and the average relative deviation between the objective function value and lower bound is 6.92%.With the increase in ship tidal ratio, both the optimization rate and objective function value of the scheme increase exponentially at first, and then tend to be stable.The inflection point appears when the tidal ratio is 50%.As the length of inbound/outbound period increases, the scheme optimization rate and target value exhibit an M-shaped trend.The optimization effect is most significant when the length of inbound/outbound period is approximately 130 min.Obviously, the ship scheduling optimization model and the hybrid algorithm are feasible.More>

2018, 18(5): 152-164. doi: 10.19818/j.cnki.1671-1637.2018.05.015

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Robust optimization on distributing routes of hazardous materials based on bi-level programming

MA Chang-xi, HE Rui-chun, XIONG Rui-qi

Abstract: To solve the optimization problem for the hazardous materials distributing routes (HMDR) with multi-distribution centers and time windows in uncertain environments, a robust optimization method with robust control parameters was proposed.Comprehensively considering the transportation risk, transportation cost and service time window in hazardous materials distributing routes, a multi-objective bi-level optimization model was constructed.The upperlevel model was used to minimize the transportation risk and transportation cost.The lower-level model was constructed as the user equilibrium traffic distribution model.With the Bertsimas-Sim robust optimization theory, the robust peer-to-peer transformation was performed on the upperlevel model with uncertain parameters.The enhanced Pareto genetic algorithm and Frank-Wolfe algorithm were combined to form a hybrid algorithm to solve the multi-objective bi-level robust optimization model.The three-stage coding and decoding method, equipotent matching crossoveroperation and flipping mutation operation were used to solve the upper-level model, and the Frank-Wolfe algorithm was used to solve the lower-level model.Taking the classical Sioux-Falls transportation network as an example, a case study was conducted to verify the rationality of the model and its algorithm for the optimization on the distributing routes of hazardous materials with3 distribution centers and 7 demand points.Research result shows that when the robust control parameters are set as 0, 30 and 60, respectively, the hybrid algorithm can obtain 3, 2 and 3 robust optimal solutions, respectively, and all solutions are delivered with the specific road sections and departure times but not the distribution order.Comparing with the traditional twostage heuristic algorithm, the hybrid algorithm can save 54.74%of the runtime.It can clearly be seen that the hybrid algorithm is superior to the two-stage heuristic algorithm both in the algorithmic efficiency and expression of the solution, and can complete the multi-objective bi-level robust optimization on the hazardous materials distributing routes in uncertain environments.More>

2018, 18(5): 165-175. doi: 10.19818/j.cnki.1671-1637.2018.05.016

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Commute activity identification based on spatial and temporal information of transit chaining breaks

JIN Hai-tao, JIN Feng-jun, CHEN Zhuo, WANG Jiao-e, YANG Yu

Abstract: An approach to improve the recognition of transfers, working commutes, and nonworking commutes in smartcard data mining was introduced.The study focus was shifted from the information of transit processes to the durations and displacements between the transit chaining breaks.The probabilities of transit chaining breaks were calculated by two dimensions of the break durations and displacements, and a joint probability distribution matrix of spatial andtemporal variables for workdays and non-working days was made.The differences between the two types of distribution were compared.The stabilities of the break duration sequences and break displacement sequences were examined.The mutation points and turning points of the two curves were marked to infer the important threshold parameters for the transferring durations and displacements generated by the transfers.A moving average filter was utilized to smooth both workdays and non-working days curves of margin duration values.The relationship between the mutation and extremes of the curve was explained for the three types of commute activities relating to the transfers, working commutes, and non-working commutes.The approach was verified by a weeklong sample dataset of the Beijing bus and subway system.The threshold parameters of the common commute activities in the dataset were determined according to the time series and the displacement sequence curve.Analysis result shows that the spatial and temporal information at the breaks can provide more reasonable identification parameters for the commute activities.A tolerance distance of approximately 1.6 km between the transit connections is found among the cardholders.The threshold of transit break duration between the transferring and non-working commutes is 22-48 min.The threshold of working and non-working commutes is approximately 478 min, and the maximum probability of non-working duration is 140 min.The transit chaining break durations of working commutes fall into a normal distribution with an expected value of 601 and a standard deviation of 44.The parameters generated by the new approach lead to an improvement in commute activity recognition, the recognition rates of the transfers, working commutes and non-working commutes increse by 16.1%, 4.2%and 6.2%, respectively.So the spatial and temporal information of transit chaining breaks can not only provide the basis for the commute activity identification, but also achieve better recognition results.More>

2018, 18(5): 176-184. doi: 10.19818/j.cnki.1671-1637.2018.05.017

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Optimization methods for traffic signal control of isolated intersection under rainy weather

LI Yan, NAN Si-rui, MA Jing, ZHOU Wen-hui, CHEN Kuan-min

Abstract: To improve the efficiency of traffic signal control at an isolated intersection under rainy weather, a traffic signal timing method was established by introducing a rainy correction coefficient.The high-resolution video of the isolated intersection under rainy weather was analyzed by using the motion analysis software, the characteristics of the saturation flow rate, lost time, and approaching speed under rainy weather were calibrated, and the rainy correction coefficients of the saturation flow rate, lost time, and approaching speed were established.A optimization model was proposed based on the simulated annealing algorithm, and the correction coefficients under various rainfall intensity levels were calculated.A VISSIM-based simulation environment was built, and the isolated intersection traffic signal control effect of the proposed modelwas evaluated under rainy weather.The traffic efficiencies of the isolated intersection using pre-timed timing control and actuated timing control with optimized parameters were compared.Analysis result indicates that the average headways under little rain, moderate rain, and heavy or torrential rain increase by 0.314%, 1.256%, and 2.871%, respectively, the average lost times increase by 1.042%, 2.829%, and 3.424%, respectively.When the flow rate is lower than 600 pcu· (h·lane) -1, the improved actuated control exhibits better performance and its average delay is 12%-23%lower than that of the original plan.When the flow rate is higher than 600 pcu· (h·lane) -1, the effect of pretimed control with the optimization is better, and the average delay is 13%-25%lower than that of the original plan, which can delay the lockout states under the saturated and over-saturated conditions and lead to the lowest delay.More>

2018, 18(5): 185-194. doi: 10.19818/j.cnki.1671-1637.2018.05.018

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Pre-warning system of maritime traffic safety risk in restricted visibility weather

DAI Hou-xing, WU Zhao-lin

Abstract: To enhance the pre-warning applicability and accuracy of maritime traffic safety risk, a pre-warning system in restricted visibility weather of the risk was set up, and it was composed of the risk matrix knowledge base, traffic flow density prediction subsystem and visibility warning subsystem.By collecting large samples, the expert survey method was modified by using the fuzzy information distribution theory under the condition of incomplete information, and the maritime traffic risk matrix was determined.The traffic density was calculated by using the short-time prediction algorithm of traffic density based on the limit learning machine theory in the artificial neural network.The regional atmospheric model system was used to divide the visibility forecast data provided by the meteorological and marine forecasting departments into spatialtemporal fine meshes, and the visible distance was calculated.The system was used to predict the visibility distance and traffic flow density of the focused sea area with spatial grids of 2 nmile by2 nmile and time step of 10 min, so as to verify the effectiveness of the system.Simulation resultshows that at 12 time points in two different time periods, the prediction accuracy rates of visible distance are 75%, 75%, 80%, 75%, 80%, 75%, 75%, 75%, 80%, 80%, 80%and 75%.The prediction accuracy rates of corresponding traffic flow densities are up to 80%.Therefore, the forecast result is reliable, and the system can realize the visualization and intelligent monitoring of navigation risk in sea area in restricted visibility weather.More>

2018, 18(5): 195-206. doi: 10.19818/j.cnki.1671-1637.2018.05.019

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