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20 May 2022, Volume 41 Issue 05 Previous Issue    Next Issue
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Transportation+Big Data & Artificial Intelligence
Transportation Infrastructure Engineering
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Transportation+Big Data & Artificial Intelligence

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Ship Allocation for LNG Maritime Transport under Combined Transport Mode of Portfolio XIE Xinlian1, NIU Dongxiang1,2, ZHAO Ruijia1, HUANG Shuai1 2022, 41(05): 1-5.  DOI: 10.3969/j.issn.1674-0696.2022.05.01 Abstract ( )   PDF (1008KB) ( )   Aiming at the problem of resource allocation of LNG maritime transport under the free on board (FOB) delivery mode and on the basis of the concept of the combined transport mode of portfolio, the models of ship allocation for LNG maritime transport under traditional trade mode and combined transport mode of portfolio with time charter were established from the perspective of the buyer, to minimize the annual transportation cost. Taking the LNG purchase and sale agreement of a LNG import company in China as an example, the rationality of the two proposed models was verified, and the optimal ship allocation and transportation plan of imported LNG route was obtained. The research results show that the combined transport mode of portfolio can reduce the transportation cost for companies more effectively than the traditional trade mode can. References | Related Articles | Metrics

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Multi-objective Multimodal Transportation Route Selection Based on Whale Optimization Algorithm WU Zhiyong1,2, DAI Yi1, JU Chuanxiang2, HU Benjia2, HU Xiao1 2022, 41(05): 6-13.  DOI: 10.3969/j.issn.1674-0696.2022.05.02 Abstract ( )   PDF (1753KB) ( )   Under the situation of vigorously promoting the adjustment of transportation structure in China, a multi-objective multimodal transport route selection model based on whale optimization algorithm was studied, in order to reduce logistics costs, improve logistics efficiency, and reduce environmental pollution caused by logistics transport emissions. The proposed multi-objective multimodal transport route selection model not only considered the transportation costs and transit costs, but also took into account the green cost of carbon emissions during transportation and the time window cost of reaching the destination city. By simulating the three processes such as target encirclement, bubble net attack and target search of whale optimization algorithm and Pareto fitness multi-objective optimization, a multi-objective multimodal transportation route selection model was established. The simulation test results show that the whale optimization algorithm has better global optimization ability and faster convergence characteristics in solving the path selection, and the proposed model has good effect and can meet transportation users’ needs of multimodal transport route selection. References | Related Articles | Metrics

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Travel Behavior Prediction of Metro Passengers Based on Attention Mechanism LSTM ZHANG Pengfei, WENG Xiaoxiong 2022, 41(05): 14-19.  DOI: 10.3969/j.issn.1674-0696.2022.05.03 Abstract ( )   PDF (1835KB) ( )   Due to the lack of micro-granularity travel behavior prediction model in metro system, a deep learning prediction framework based on attention mechanism LSTM was proposed to predict the travel behavior of passengers in metro system. As the travel information of the passengers in metro system had the characteristics of high latitude and multi-forms, two feature extraction modules were proposed to capture the temporal and spatial features respectively. By use of the attention mechanism and the characteristics of LSTM neural network, the sequential characteristics of long travel sequence were modeled, so as to predict the temporal and spatial information of passengers next trip. AFC data of Guangzhou Metro was used to verify the proposed model. The results show that the proposed time information feature extraction method can more accurately characterize the time feature. Compared with the conventional statistic learning models, the prediction accuracy for inbound station, outbound station points and inbound time of the proposed prediction model has reached 74.9%, 61.6% and 44.8% respectively, which has been greatly improved compared with the existing algorithms. References | Related Articles | Metrics

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Short-Term Forecast Model of Railway Passenger Flow Based on Ensemble Algorithm LIU Jie 2022, 41(05): 20-25.  DOI: 10.3969/j.issn.1674-0696.2022.05.04 Abstract ( )   PDF (2480KB) ( )   With the completion and operation of high-speed railway passenger dedicated lines in succession, a certain amount of passenger flow historical data has been accumulated. In order to reasonably allocate transport capacity and improve transport service quality, it is necessary to fully mine the historical data for short-term prediction of passenger flow. On the basis of considering the samples of different length time series, an integrated model for short-term passenger flow prediction was proposed. Firstly, based on the sampling of the original OD passenger flow data between stations, the variable length time series comprehensively reflecting the characteristics of passenger flow were obtained as the samples. Secondly, the wavelet decomposition and ARIMA model were combined to build a weak passenger flow prediction model. Finally, the AdaBoost integration algorithm was used to combine multiple weak models to build a strong passenger flow prediction model. Based on the passenger flow data of Chongqing-Wanzhou line, the parameters of the proposed model were calibrated and tested. The research shows that the proposed model has better prediction accuracy and generalization ability than GM(1,1) and ARIMA, and has an average improvement of 38.12%, 67.78% and 38.52% in the three indexes of average absolute error, average relative error and mean variance. References | Related Articles | Metrics

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Bus Choice Behavior of University Students Based on Structural Equation Model ZHANG Tao, SUN Fan, JIN Minjie, JIA Qinglin 2022, 41(05): 26-34.  DOI: 10.3969/j.issn.1674-0696.2022.05.05 Abstract ( )   PDF (1896KB) ( )   In order to enrich the variable relationship in the existing college students’ bus choice model, based on the planned behavior theory, the intermediary variables personal preference and experience regret were added to the theoretical framework of behavior intention determined by three variables: behavior attitude, subjective norms and perceived behavior control. The college students’ bus choice model considering 7 latent variables and 21 observation variables was established to reveal the interaction mechanism between latent variables after adding 2 new variables. Finally, the actual data of four universities in Taiyuan were used in the proposed model. The model calibration results show that behavior attitude has a negative impact on college students’ bus choice behavior, which is different from previous studies. Both personal preference and experience regret have a significant impact on intention and choice of bus travel, but contrary to the regret theory, the experience regret has a positive effect on bus selection. References | Related Articles | Metrics

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Research on Intersection Self-adaptive Control Based on Traffic Flow Arrival Rate Prediction ZHANG Weihua, LI Jun, DING Heng, XIE Lipeng 2022, 41(05): 35-42.  DOI: 10.3969/j.issn.1674-0696.2022.05.06 Abstract ( )   PDF (2280KB) ( )   Aiming at the problem of low efficiency of induction control at urban road intersections, taking the classic four-phase control of urban road intersections as the research object, a self-adaptive control method to predict and calculate vehicle arrival rate based on the signal timing parameters of upstream intersection was proposed. According to the parameters such as vehicle arrival rate λ and vehicle speed dispersion coefficient F, an optimization model of traffic signal timing parameters was established. Taking a key intersection in Hefei city as an example, the proposed self-adaptive control method was used for traffic simulation analysis, and compared with the traditional induction control method. The results show that the maximum queue length, the average number of stops, the total delay and the total fuel consumption calculated by the self-adaptive control method are 21.7%, 9.0%, 12.6% and 9.6% lower than those calculated by the induction control method respectively, which effectively improves the traffic efficiency of intersection. References | Related Articles | Metrics

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Distribution Feature Model of Debris in Side Impact of Smart Tracking Vehicle WANG Zhanyu1, SHEN Yamin1, DU Xuejing1, LIANG Wenzhi1, HU Yan2 2022, 41(05): 43-50.  DOI: 10.3969/j.issn.1674-0696.2022.05.07 Abstract ( )   PDF (2763KB) ( )   In order to analyze the distribution characteristics of the debris in the collision of vehicles and the influence of different types of scattered materials on the distribution characteristics, the real vehicle collision test of the intelligent tracking truck and passenger car models was designed, to provide a reference for the inference of collision speed in automobile accident reproduction. Through the full side impact test simulation of two types of vehicles, the relationship among the distribution area, mass and collision speed of the debris at the accident site was analyzed. The research results show that the debris of different material types have their own scattering trends when a side collision occurs. Among them, soybean has the largest scattered area and melon seeds have the largest scattered mass. There is a significant mathematical relationship between the scattering area and mass of the scattered objects with the same material and the collision velocity. References | Related Articles | Metrics

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Study on Influence of Distracted Driving on Curves on Road Safety Risk ZHANG Zhiqing1, FU Jinxiu1, XIAO Shuying1, LIANG Changzheng2 2022, 41(05): 51-56.  DOI: 10.3969/j.issn.1674-0696.2022.05.08 Abstract ( )   PDF (1103KB) ( )   In order to explore the internal causes of driving safety risks caused by distracted driving on curves, five road conditions were selected, including straight road segment and curve road segment with radius of 125, 200, 400 and 600 m. By use of the driving simulation system, the changes of driver’s steering wheel operation, psychological comfort and vehicle lateral offset when the driver had cognitive distraction and visual distraction were studied. The results show that under the same distracted state, the effects of distracted driving on steering wheel rotation angular velocity ω, vehicle lateral L and driver’s heart rate in curved road segment are greater than those in straight road segment. The smaller the curve radius, the more significant the impact, and the higher the driving safety risk. Under the same road alignment condition, the effects of visual distracted driving on driving behavior, vehicle position and driver comfort are far greater than those of cognitive distracted driving. When driving with visual distraction on a curve with a radius of 125 m, the lateral offset of the vehicle approaches the dangerous critical value, and the driving safety risk increases greatly. References | Related Articles | Metrics

Transportation Infrastructure Engineering

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Service Status and Analysis Method Prospect of Chongqing Municipal Bridges Based on Detection Information TANG Qizhi1, 2, XIN Jingzhou1, 2, ZHOU Jianting1, 2, ZHANG Xianghe3, YANG Hong3 2022, 41(05): 57-65.  DOI: 10.3969/j.issn.1674-0696.2022.05.09 Abstract ( )   PDF (3431KB) ( )   Municipal bridge is an important lifeline in the urban traffic network, and its health is related to the service quality of urban operation. Based on the detection reports of 191 detected bridges in Chongqing in the past two years, the service status, detection and evaluation methods and data utilization conditions were comprehensively sorted out, which was in order to grasp the current status of urban bridge, explore the existing problems and technical needs, and promote the further development of bridge detection and evaluation. The investigation results show that the service status of Chongqing municipal bridges is good. The evaluation method of technical condition needs to be updated and improved. There are few application scenarios for intelligent detection methods, and there is a huge engineering demand for non-destructive detection technology of hidden diseases. And the utilization rate of bridge detection data is low and the excavation depth is not enough. The research results can provide an important reference for the study of deterioration law, condition assessment, and maintenance decision-making based on bridge detection data. References | Related Articles | Metrics

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Cable-Saddle Anti-slipping Test of AS Method Suspension Bridges SU Yang1, FU Yafeng1, XIE Jun2, CHEN Long2, HUANG Anming2 2022, 41(05): 66-73.  DOI: 10.3969/j.issn.1674-0696.2022.05.10 Abstract ( )   PDF (3357KB) ( )   For suspension bridges constructed by AS method, the number of single strand steel wires is much more than that of PPWS method, the cable saddle groove is much wider than that of PPWS method, and the thickness of diaphragm between notches is also increased to 10 mm. Yangbaoshan suspension bridge on Gui-Huang expressway is a long-span suspension bridge constructed by using AS method to erect main cable for the first time in China. In order to clarify the sliding mechanism between the main cable and the cable saddle and verify the anti-sliding reliability, the influence of each contact surface in the saddle groove on the anti-sliding coefficient was studied through experiments, taking Yangbaoshan suspension bridge as the background. Results show that the cable strands in the saddle groove slide layer by layer, and the sliding sequence is always from the upper cable strand to the lower cable strand. The nominal friction coefficient increases progressively from the upper cable strands to the lower cable strands. Different contact states of the main cable steel wire in the saddle groove correspond to different foundation friction coefficients. The foundation friction coefficients of cable strand and groove bottom, cable strand and side wall, cable strand and diaphragm and cable strand and cable strand are 0.25, 0.35, 0.25 (5 mm diaphragm), 0.3 (10 mm diaphragm) and 0.21 respectively. Increasing the thickness of saddle groove diaphragm can effectively increase the structural stiffness, improve the foundation friction coefficient and improve the overall anti-sliding performance of saddle groove. It is suggested that the value of friction coefficient between the main cable and saddle in AS method suspension bridges should be 0.2. References | Related Articles | Metrics

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Structural Response and Driving Evaluation of Cable-Stayed Bridge Based on Wind-Vehicle-Bridge Coupling Vibration SONG Tengteng1,2, JING Guoqiang3,4, WU Xiaobo3,4, WANG Zhengxing3,4, YAN Chao5 2022, 41(05): 74-81.  DOI: 10.3969/j.issn.1674-0696.2022.05.11 Abstract ( )   PDF (2746KB) ( )   To realize the structural response analysis and driving comfort and safety evaluation of cable-stayed bridge under the combined action of wind and random traffic flow, the wind-vehicle-bridge coupling vibration analysis system was firstly improved. Secondly, the improved harmonic synthesis method was adopted to simulate the three-dimensional wind field of the whole bridge, and the dynamic responses of structure and vehicle were analyzed under the combined effect of wind and random traffic flow. Finally, driving safety and comfort evaluation criteria were established, and the influences of wind speed, vehicle speed and road surface roughness on driving comfort were investigated. Combined with the parameters of speed and wind direction, the critical wind speed of high compartment truck was determined. The results show that the dynamic response of bridge structure and high compartment truck in dense operation state is greater than that in sparse operation state. In the random traffic flow of dense operation state, the lateral comfort of high compartment trucks decreases with the increase of wind speed, and the vertical comfort decreases with the increase of vehicle speed and the deterioration of pavement roughness level. Its 1/3 frequency acceleration RMS index peak influence range is between 2~10 Hz, which meets the requirements of driving comfort. Based on the established analysis process, the critical wind speed of driving accident under specific speed and wind deflection angle can be determined. When the speed is 60km/h and the wind deflection angle is 70°, the critical wind speed of driving accident is 23.7m/s. References | Related Articles | Metrics

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Solution and Analysis of Dynamic Response for Layered Pavement Structure Based on PIM ZHANG Haiting1, YANG Linqing2,3, GUO Fang4 2022, 41(05): 82-91.  DOI: 10.3969/j.issn.1674-0696.2022.05.12 Abstract ( )   PDF (1968KB) ( )   In order to evaluate the service performance of pavement more accurately, a numerical model to solve the dynamic response of viscoelastic layered pavement structure was established, which was according to the measured results of the falling weight deflectometer and based on the precise integration algorithm, so as to provide an efficient and accurate forward algorithm for pavement deflection inversion analysis. The proposed algorithm was reduced to an elastic model and compared with the existing frequency domain examples, and the accuracy of the frequency domain solution of the proposed algorithm was verified. At the same time, the viscoelastic solution of the calculated time domain results was compared with the elastic solution and the measured value of the falling weight deflectometer, and the accuracy of the proposed algorithm in solving the dynamic response of layered pavement structure under FWD dynamic load and its applicability to practical engineering were verified. Finally, the influence of asphalt concrete layer and pavement base thickness on the dynamic displacement response of pavement under FWD dynamic load was analyzed by using the proposed algorithm. The results show that the two parameters have significant influence on the dynamic response. References | Related Articles | Metrics

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Crack Resistance Performance of Cement-Soil Stabilized RAP Mixture Based on Pre-slit Test PENG Bo1, YANG Zhongchang1, REN Ziming2, WU Shiyuan3, DU Bingjie2 2022, 41(05): 92-99.  DOI: 10.3969/j.issn.1674-0696.2022.05.13 Abstract ( )   PDF (1904KB) ( )   In order to analyze the crack resistance performance of cement-soil stabilized RAP mixture, specimens with different proportions were molded with the optimum moisture content and maximum dry density to undergo shrinkage test and fracture toughness test. The test results show that, with the increase of lime soil and cement content, the dry shrinkage coefficient and temperature shrinkage coefficient of the mixture show an overall growth trend. When the mixture is in the temperature range of 5~-5 ℃, the temperature shrinkage coefficient has a peak value, and the peak value increases with the increase of cement dosage. The fracture toughness test results of the mixture show that the fracture toughness of cement-soil stabilized RAP mixture increases with the increase of cement dosage or the decrease of lime soil dosage, indicating that the anti-crack propagation ability of the mixture also increases. And the fitting results show that the flexibility and the shrinkage coefficient have a high correlation, which means that the flexibility can accurately reflect the shrinkage resistance of the mixture. Based on this, the comprehensive consideration of fracture toughness and flexibility is proposed as the evaluation index of crack resistance of cold recycled mixture. References | Related Articles | Metrics

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Influence of Limestone Powder on Rheological Properties of Ultrahigh Strength Cement-Based Materials NAN Xueli1,2, JI Jianrui1,2, WEI Dingbang3, WANG Yi1,2, CHEN Hao1,2 2022, 41(05): 100-106.  DOI: 10.3969/j.issn.1674-0696.2022.05.14 Abstract ( )   PDF (2582KB) ( )   In order to prepare ultrahigh strength cement-based materials that was ecological and more suitable for engineering applications, limestone powder was used to replace the cement and silica fume in the ultrahigh strength cement-based materials, and the influence of limestone powder on the rheological characteristics of ultrahigh strength cement-based materials was studied by micro slump meter and rheometer. The results show that when limestone powder replaces part of the cement and silica fume, the ultrahigh strength cement-based materials appears shear thickening, and the yield stress and plastic viscosity are reduced, indicating that the mixing of limestone powder can improve the segregation and bleeding of ultrahigh strength cement-based materials during pumping, and can improve the filling capacity of ultrahigh strength cement-based materials during pouring. Compared with limestone powder replacing cement, when limestone powder replaces silica fume, the shear thickening degree and fluidity of ultra-high strength cement-based materials are significantly increased and the yield stress and plastic viscosity are significantly reduced, indicating that replacing silica fume can greatly improve the construction performance of ultrahigh strength cement-based materials. The fluidity, yield stress, and plastic viscosity of ultrahigh strength cement-based materials meet the quadratic polynomial function relationship. When the replacement amount of limestone powder for cement should not exceed 17% and the replacement amount of silica fume should be 50%, the rheological properties of ultrahigh strength cement-based materials are greatly improved, and the 28-day compressive strength increases by 15.6%. References | Related Articles | Metrics

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Stability Evolution Process of Rainfall-Type High-Cut Slope Based on Chen-Young Model and Unbalanced Thrust Method JIN Honghua1, WANG Linfeng2, REN Qingyang1, ZHANG Xingxing3 2022, 41(05): 107-117.  DOI: 10.3969/j.issn.1674-0696.2022.05.15 Abstract ( )   PDF (4156KB) ( )   In order to further reveal the process of rainfall infiltration and stability evolution of bedrock stepped high-cut slope under rainfall conditions, a conceptual model of bedrock stepped high-cut slope was established based on the Chen-Young model and unbalanced thrust method, and the stability calculation method of this type of high-cut slope under rainfall conditions was deduced. Geo-studio numerical simulation software was used to study the rainfall infiltration process of the high-cut slope under multiple conditions, and the internal seepage field and stability variation laws of the high-cut slope under different rainfall conditions and after rain were revealed. The stability changes of this type of slope under different rainfall time and rainfall intensity were obtained, and the stability prediction method of this type of high-cut slope under different rainfall volume and rainfall time was given. The research results show that: different from the inclined slope, the size effect of high-cut slope should be considered in the rainfall infiltration process of this type of slope. According to the relationship between rainfall infiltration depth and slope shape and size, the infiltration process of this kind of slope can be divided into three modes, in which the potential sliding surface of this type of slope under the condition of heavy rainfall is a double-folded sliding surface of wet front and bedrock surface, and the simulation results are in good agreement with the model calculations. The degradation process of stability of the high-cut slope under rainfall conditions can be divided into four stages: stationary stage, rapid degradation stage, slow degradation stage, and recovery stage. The stability of high-cut slope is negatively correlated with rainfall time and rainfall intensity. When the total rainfall is consistent, the rainfall time affects the slope stability more severely than the rainfall intensity does. The greater the rainfall infiltration depth and the total rainfall amount, the smaller the recovery amplitude of the stability coefficient of the high-cut slope after rain. References | Related Articles | Metrics

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Stability Analysis of Reservoir Bank Slope under the Coupling Action of Water Level Fluctuation and Rainfall ZENG Runzhong1, XIE Dian1,2, ZHU Junhua1, LUO Wei1, ZHAO Xiushao1 2022, 41(05): 118-126.  DOI: 10.3969/j.issn.1674-0696.2022.05.16 Abstract ( )   PDF (2779KB) ( )   In order to study the seepage and stability of unsaturated complex soil reservoir bank slope under the combined action of rainfall and reservoir water level fluctuation, a calculation model of sand bearing slope was established based on ABAQUS software. Under the conditions of rainfall intensity of 48.0, 72.0 and 100.8 mm/d and reservoir water level fluctuation rate of 0.5, 1.0 and 1.5 m/d, the seepage field characteristics and stability of reservoir bank slope were analyzed. The results show that under the influence of single factor, the greater the rainfall intensity or the water level falling rate, the worse the stability of the reservoir bank slope. Under coupling action of rainfall and water storage (rise of reservoir water level), rainfall intensity and water storage have relatively little impact on the stability of reservoir bank slope. Under coupling action of rainfall and reservoir water level drop, the water level drop is the dominant factor causing the rapid decline of reservoir bank slope stability, and the reservoir bank slope stability decreases with the increase of rainfall intensity. The effect of seepage force promotes the connection of the plastic zone of the sand bearing slope and greatly weakens the stability of the reservoir bank slope. References | Related Articles | Metrics

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Mechanical Model of Load-Bearing Response of Floating Bollard of Ship Lock LIU Mingwei1, LI Minglong1, WU Linjian1, JIANG Tao2, ZHAO Dianpeng3 2022, 41(05): 127-132.  DOI: 10.3969/j.issn.1674-0696.2022.05.17 Abstract ( )   PDF (2271KB) ( )   With the rapid development of large-scale navigation ships, higher requirements were put forward for navigation facilities such as floating bollard of ship lock. In order to ensure the mooring safety of the floating bollard structure of the ship lock in operation, the quantitative relationship between ship mooring force and floating bollard body strain was deduced, which was relied on a certain large-scale ship lock project and based on the basic theory of material mechanics. Combined with the calculation results of the strain value of the floating bollard finite element model under the action of the mooring force, the load-bearing response mechanical model of the ship lock floating bollard was established. When the strain at the measuring point at the same section of the floating bollard was known, the mooring force of the floating bollard can be calculated based on the proposed model, so as to evaluate the mooring safety of the ship passing through the lock. By comparing the predicted value of the proposed model with the calculation result of numerical simulation, the accuracy of the proposed model was verified. The research results can provide technical support for realizing automatic sensing warning and safety assessment of floating bollard of ship lock in service state. References | Related Articles | Metrics

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Automatic Drawing of Shield Tunnel Segment Structure Based on DXF Group Code GONG Yanfeng1,2，CHENG Yan3,4，LIU Xiaodi3,4，WANG Shaofeng1,2 2022, 41(05): 133-141.  DOI: 10.3969/j.issn.1674-0696.2022.05.18 Abstract ( )   PDF (3112KB) ( )   The drawing process of current shield segment structure is mainly realized by designers with the help of CAD drawing software, the process is complex and it’s difficult to accurately and quickly realize the drawing of segment structure elevation and section. On the basis of clarifying the drawing requirements of segment structure, the parametric design of each component of segment structure was carried out by studying the group code format of DXF file, defining the basic elements, and combining with the geometric parameter characteristics of shield tunnel segment structure. Based on geometric Boolean operation, the segment structure contour was extracted, and the position of each component was determined, and each component was assembled to form a complete structure diagram. Using C++ programming language and based on the idea of object-oriented, the modular design was carried out, the automatic drawing software of segment structure was developed, and the segment structure diagram was automatically generated. The results show that the proposed design has high precision and fast speed and improves the production efficiency of designers. References | Related Articles | Metrics

Transportation Equipment

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Temperature Field and Thermal Stress of External Rotor In-Wheel Motor ZHOU Zhigang1,2, YANG Wenhao1,3, LI Zhengzheng1, LI Haodi4 2022, 41(05): 142-150.  DOI: 10.3969/j.issn.1674-0696.2022.05.19 Abstract ( )   PDF (4193KB) ( )   Considering that external rotor in-wheel motors adopted different cooling methods to cause different temperature rise distribution and had different effects on the motor deformation, an external rotor in-wheel motor model was established to analyze the magnetic field of the motor. By using the loss in the motor as a heat source, the coupling analysis of the motor temperature field and temperature stress was carried out, so as to study the temperature rise and deformation distribution of each component of the external rotor in-wheel motor when different cooling methods were used. Based on this, the deformation difference between single motor and in-wheel motor was compared. By comparing the experimental data with the finite element data, the maximum error of the motor component’s temperature is 6.6%, which verified the correctness of the proposed model of the external rotor in-wheel motor. The results show that different cooling methods have different effects on the temperature distribution and the deformation of the motor. The deformation results of the single motor and the in-wheel motor are different under the same cooling condition. This research provides a certain reference value for motor performance, life and safety. References | Related Articles | Metrics

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Influence Rule of Belt Cord Performance Parameters of Running Wheel Tire on Tire Wear WEN Xiaoxia1, TIAN Yunkun1, DU Zixue2 2022, 41(05): 151-156.  DOI: 10.3969/j.issn.1674-0696.2022.05.20 Abstract ( )   PDF (1945KB) ( )   The running wheel tires of straddle type monorail vehicles will be seriously worn in actual operation. In order to clarify the influence rule of elastic modulus and angle change of belt ply cord on tire wear performance, the radial stiffness of running wheel was taken as the evaluation index of tire wear performance. The variation rule of radial stiffness of running wheel tire changing with different elastic modulus of belt ply cord and angle of belt ply cord was studied, and the sensitivity analysis of the influence factors of the angle of the belt ply cord was carried out. The research results show that the elastic modulus of belt ply cord has little effect on the wear performance of tire; the second belt ply cord angle of the running wheel tire has the greatest and most sensitive effect on the wear performance of tire; the larger the second belt ply cord angle, the worse the wear performance of running wheel tire; the larger the first and third belt ply cord angles, the better the wear performance of running wheel tire. References | Related Articles | Metrics

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Optimal Design of Hybrid Fluid Flow Magnetorheological Damper Based on Genetic Algorithm HU Guoliang, QI Haonan, YU Lifan, TU Yu 2022, 41(05): 157-166.  DOI: 10.3969/j.issn.1674-0696.2022.05.21 Abstract ( )   PDF (2455KB) ( )   Aiming at the deficiency that the traditional MR damper could not produce good damping performance under the condition of limited volume, a hybrid flow MR damper was proposed and designed. The liquid flow channels of the proposed MR damper were consisted of four axial annular liquid flow channels and two radial disc liquid flow channels in series. By setting magnetic isolation parts to guide the magnetic line of force to meander through all liquid flow channels, the utilization rate of magnetic field of the damper was effectively improved. The structure and working principle of the hybrid fluid flow MR damper was described, and its damping force mathematical model was also established. Finite element method was used to simulate the electromagnetic field of the proposed damper. Genetic algorithm was used to optimize the proposed damper structure. The optimization objective function consisted of five parts: output damping force, adjustable range of damping force, response time constant, energy consumption and volume of damper piston head. The distribution laws of magnetic induction intensity and shear stress at each liquid flow channel before and after optimization, as well as the variation of performance indexes changing with the applied current were compared and analyzed. The results show that the magnetic field utilization rate of the MR damper after optimization is higher, and each performance is significantly improved. References | Related Articles | Metrics