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01 November 2023, Volume 42 Issue 10 Previous Issue   
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Transportation+Big Data & Artificial Intelligence
Transportation Infrastructure Engineering
Transportation Equipment


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Transportation+Big Data & Artificial Intelligence

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Summary on Characteristics and Transport Laws of Fluid Mud LIU Jie1, ZHOU Peng2，MENG Caixia1 2023, 42(10): 1-11.  DOI: 10.3969/j.issn.1674-0696.2023.10.01 Abstract ( )   Fluid mud is extensively found in estuaries, coasts, inland rivers and reservoirs and it is a key factor to cause channel siltation, topographic evolution and environmental pollution. In response to the formation mechanism and observation method of fluid mud, the consolidation mechanism, rheological and thixotropic characteristics of fluid mud, as well as the transport laws of fluid mud, were summarized and discussed. However, the expression forms and application conditions of research results at present are different, which are difficult to be widely used in practical engineering. On this basis, the internal structure of fluid mud, external loads and the influence of biological factors, as well as the systematic study on characteristics and transport laws of fluid mud in large reservoirs should be focused. References | Related Articles | Metrics

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Numerical Study on Flow Field and Backflow Characteristics of Double Spur Dikes FAN Xiaobiao，ZENG Qian，JI Nan，QIAN Zhipeng，DENG Xiaobing 2023, 42(10): 12-21.  DOI: 10.3969/j.issn.1674-0696.2023.10.02 Abstract ( )   Double spur dikes are a common type of spur dike arrangement. Different arrangements and lengths of spur dikes will have different impact on the channel regime, water level and the effect of flow rectification and bank protection. In order to investigate the effect of double spur dikes on the river channel, the numerical simulations of the flow field and reflux characteristics of double spur dikes were carried out, which were based on the RANS equations and combined with the Realizable k-ε turbulence model. Firstly, the hydrodynamic characteristics of the spur dikes were simulated numerically and compared with the experimental data to prove the rationality of the numerical simulation method. Then, the effects of the length of the spur dike (river width narrowing rate) and the distance between spur dikes on changes in waterway water level, flow velocity and reflux zone were investigated. The research results show that when the dike spacing is constant, with the increase of the river width narrowing rate, the height and range of the upstream water of the spur dike increase, the pick-up effect is enhanced; the mainstream contraction section decreases, the flow velocity increases, and the protection range of the channel increases. As the narrowing rate increases, the ratio of the length and width of the backflow between the dams to the dam length decreases, and the ratio behind the dam increases. When the dam length is constant, as the dam spacing increases, the depression area of the water level shrinks from the downstream of the spur dike to between the two spur dikes. When the dike length is 5m and the dam spacing is 10m, the downstream of the spur dike generates oscillation, and the waves formed by the water surface propagate downstream. With the increase of dike spacing, the ratio of the length and width of the backflow between the dikes to the dam length increases, and the ratio behind the dike decreases. When the dike length is 5m and the dam spacing is 10m, the water flows back to form a counterclockwise vortex between two dikes. The research results can provide a reference for the construction of double spur dikes for channel revetment. References | Related Articles | Metrics

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Effect of Pier Anti-collision Facilities on Turbulence Width ZHANG Yijun1, TAN Zhirong2,3, LIU Jingxian2,3, LI Xiaochen2 2023, 42(10): 22-28.  DOI: 10.3969/j.issn.1674-0696.2023.10.03 Abstract ( )   Different forms of anti-collision structures of bridges will result in different turbulence widths, which will thereby affect the safe navigation of ships. Therefore, it is necessary to study the influence mechanism of the anti-collision facilities on turbulence widths. The three-dimensional flow field with different anti-collision facilities was simulated by using computational fluid dynamics, the turbulent flow width of bridge piers under different working conditions was measured, and the effects of vortex field and velocity field on the turbulent flow width were analyzed. The research results show that the turbulence width of anti-collision facilities with pointed bow is the smallest, while the turbulence width of anti-collision facilities with round bow is the largest. The reason for this is that the isolation effect of the pointed bow effectively weakens the interaction between spanwise vortices and shear layer on both sides of anti-collision facilities, playing a partial rectification role. Especially, the situation of larger scale spanwise vortices breaking into smaller scale vortices has been alleviated, and the vortex body positions are relatively concentrated. While the anti-collision facilities with round bow enlarges the water resistance characteristics of the bridge pier, resulting in an increase in turbulence width. Therefore, in order to reduce the impact of anti-collision facilities on the turbulent flow pattern, the anti-collision structure with pointed bow should be adopted. References | Related Articles | Metrics

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Theoretical Analysis of Slip Resistance between Main Cable and Cable Saddle of Self-anchored Suspension Bridge DUAN Ruifang 1, BAI Yunteng 2, XUE Yuanyuan2，HUANG Chunyang2 2023, 42(10): 29-37.  DOI: 10.3969/j.issn.1674-0696.2023.10.04 Abstract ( )   In order to accurately evaluate the anti-slipping safety between main cable and cable saddle and ensure the structural safety of self-anchored suspension bridge in the process of rapid construction, the anti-slipping performance analysis between main cable and cable saddle needs to be studied. By exploring the theoretical basis of the existing lateral force calculation formula, the accuracy of different lateral force calculation methods was evaluated. Based on the lateral force analysis theory of discrete body contact relation, the improved expression of anti-slipping safety factor of main cable and cable saddle was deduced, the safety factor measurement index under construction state and bridge completion state was improved, and the failure criterion and failure mode of main cable under different states were established. The results show that the friction coefficient between the cable saddle and the main cable and the structural parameters of the saddle are the main factors affecting the anti-slipping performance of the main cable at the cable saddle, and the optimization of the structural parameters of the cable saddle and the setting of metal baffle in the cable saddlle can effectively improve the anti-slipping safety of the main cable. References | Related Articles | Metrics

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Comprehensive Judgment of Reinforcement or Demolition Scheme of Concrete Arch Bridge Based on Rough Set Theory ZHANG Shenglin1，ZHOU Shuixing2，GENG Chuanyan2，YE Hang2，LIU Bin3 2023, 42(10): 38-44.  DOI: 10.3969/j.issn.1674-0696.2023.10.05 Abstract ( )   From 1960s to 1990s, a large number of double-curved arch bridges and truss composite arch bridges were built in China. Serious diseases occurred during operation, and many arch bridges were forced to be reinforced or demolished and reconstructed. However, the reinforcement or demolition of arch bridges involved many factors, such as technology, economy, society and resources. The current studies usually only considered the technical status of bridges, and it was difficult to make a scientific and reasonable decision-making scheme. In view of the shortcoming of the singularity of decision-making factors, according to the diseases of double-curved arch bridge and truss composite arch bridge, the evaluation index system including “technical category, social category and economic category” was constructed from the aspects such as technical status, social development, national policy, government behavior, social resources and life cost. Based on rough set theory, a comprehensive judgment model for the reinforcement or demolition scheme of concrete arch bridge was established, which had rigorous calculation logic, simple index weight determination and accurate judgment results. And the proposed model was applied to Huayudong Bridge in Guizhou Province. The results show that the proposed evaluation index system can objectively carry out the comprehensive judgment of the reinforcement or demolition scheme of the concrete arch bridge and verify the feasibility of the comprehensive judgment model. References | Related Articles | Metrics

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Prediction Method of Asphalt Pavement Life after Semi-rigid Base Cracking FANG Naren1,5，HU Shiqing2,4，WU Zhaoyue3，SUN Yaoning5，HAN Jinchuan1 2023, 42(10): 45-52.  DOI: 10.3969/j.issn.1674-0696.2023.10.06 Abstract ( )   According to the pavement fatigue life prediction criterion that the fatigue life of semi-rigid base asphalt pavement consists of two stages such as crack generation and crack propagation, the fatigue life prediction equation of semi-rigid base asphalt pavement for the purpose of preventing reflective cracks was proposed. The proposed equation was composed of two parts: the life of the crack initiation stage and the life of the crack propagation stage. The accuracy of the proposed equation was verified by taking Kayemo Expressway as an example. The results show that the stress intensity factor K1 under the action of temperature load is significantly smaller than the shear-type stress intensity factor K2 produced under the action of traffic load. In the process of reflective crack propagation, the crack propagation is affected by temperature and load in the early stage and is mainly affected by traffic load in the later stage. In the case of penetrating cracks in the semi-rigid base course, the crack initiation life of the pavement is very small and almost negligible, so the corresponding asphalt layer bottom at the crack is easy to crack. In the crack propagation stage, the thickness of the surface layer has the greatest impact on the reflective crack propagation life of the semi-rigid base asphalt pavement, followed by the surface layer modulus; the thickness and modulus of the base layer have little effect on it. Therefore, the service life of semi-rigid base asphalt pavement can be increased by increasing the thickness of the surface layer or reducing the surface layer modulus. References | Related Articles | Metrics

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Effect of Filler on the Fatigue Performance of Waterborne Epoxy Resin Emulsified Asphalt Mastic HUANG Weirong1, JIANG Tao2, LI Huailong3, REN Haisheng4 2023, 42(10): 53-60.  DOI: 10.3969/j.issn.1674-0696.2023.10.07 Abstract ( )   In order to study the effect of different filler types and powder to binder ratios on the fatigue performance of waterborne epoxy resin emulsified asphalt (WEREA) mortar, the stress-time scanning mode in the dynamic shear rheometer (DSR) was used to test the fatigue performance of WEREA mortar with different types of fillers and different dosages. The fatigue performance of WEREA mortar was evaluated by taking Nf50 and NG* as indicators. Moreover, the linear fitting method was used to analyze the effects of filler content, filler type, stress level and emulsified asphalt self-charge on the fatigue performance of WEREA mortar. The scanning electron microscope (SEM) was used to observe the microstructure of the typical WEREA mortar, and to verify and further analyze the fatigue performance test results. The research results show that the filler content and the fatigue life of the mortar are linearly and highly positively correlated. The cement has a better improvement effect on the fatigue life of the mortar than mineral powder does, which is 4 times more than mineral powder under 0.10 MPa stress, and about 1.9 times more than mineral powder under 0.15 MPa stress. The difference in the degree of influence of the charge type on the fatigue performance of WEREA mortar is very small. There are fewer wrinkles in the cement-WEREA mortar under the microstructure, and the shrinkage stress generated by cement hydration is an important factor to improve the fatigue life of the mortar. References | Related Articles | Metrics

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Influence of Diatomite Content and Fineness on Asphalt Performance LIU Liping1,2, YAN Tiecheng1,2, DU Ting1,2, GUO Jianbo1,2 2023, 42(10): 61-68.  DOI: 10.3969/j.issn.1674-0696.2023.10.08 Abstract ( )   The research on diatomite as a modifier for asphalt and asphalt mixtures has been going on for a long time. In order to provide reasonable suggestions for the application of diatomite in modified asphalt, dynamic shear rheology test (DSR), bending creep stiffness test (BBR) and multi-stress creep recovery test (MSCR) were used to study the performance of asphalt slurry with different diatomite content and fineness. Fourier transform infrared absorption spectrometer (FTIR) and scanning electron microscopy (SEM) were used to analyze the mechanism of diatomite on asphalt. The results show that: the high-temperature resistance to permanent deformation of diatomite modified asphalt slurry continuously increases within the range of increasing the content of diatomite from 10% to 20% and increasing the fineness mesh from 200 mesh to 800 mesh, but the degree of improvement gradually decreases. Diatomite has a negative effect on the low-temperature performance of asphalt, and under the same dosage conditions, the influence of the fineness of diatomite on the low-temperature performance is not significant. The modification effect of diatomite on asphalt mainly depends on the physical properties of diatomite and the degree of blending between the two. The research results show that diatomite can effectively improve the high temperature performance of asphalt, and its impact on the low-temperature performance of asphalt is not significant. Considering both performance and economy comprehensively, it is recommended that the amount of diatomite is 20%, and the fineness is 500 mesh. References | Related Articles | Metrics

Transportation Infrastructure Engineering

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Construction of Aggregate Model Based on PFC SHI Hanyong1，MA Ruiqing2，XIAN Jianglin3，CHEN Geyu4 ，GUO Peng5 2023, 42(10): 69-74.  DOI: 10.3969/j.issn.1674-0696.2023.10.09 Abstract ( )   In the discrete element program PFC3D, the method of randomly cutting spherical particles was used to establish the discrete element digital model of the coarse aggregate particles, the clump cluster was used to simulate the shape of the coarse aggregate, and the surface of the clump was extracted to characterize the structure of the aggregate. Secondly, a virtual screening test was conducted to verify the reliability of the digital aggregate by tracking the pass rate of the aggregate, so as to verify the accuracy of the random cutting method. The results show that the simulated vibration screening test can verify that the size of the digital aggregate generated by random cutting is consistent and accurate with the particle size of the real aggregate to a certain extent. It is feasible to use vibration screening test to evaluate the quality of PFC3D randomly generated digital aggregates. References | Related Articles | Metrics

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Experimental Study on Dynamic Characteristics of Lime Phosphogypsum Stabilized Red Clay CHEN Kaisheng, LUO Guofu, ZHOU Bo, WANG Lei 2023, 42(10): 75-82.  DOI: 10.3969/j.issn.1674-0696.2023.10.10 Abstract ( )   The dynamic characteristics tests of plain red clay and lime phosphogypsum stabilized red clay were carried out by indoor SDT-20 dynamic triaxial testing machine. The variation laws of dynamic shear modulus and damping ratio of plain red clay and lime phosphogypsum stabilized red clay under different confining pressures, consolidation ratios and vibration frequencies were studied, and the dynamic constitutive relationship between dynamic shear modulus and damping ratio was proposed. The research results show that plain red clay and lime phosphogypsum stabilized red clay increase with the increase of confining pressure, consolidation ratio, frequency and lime content. The damping ratio decreases gradually with the increase of confining pressure, consolidation ratio, frequency and lime content. Under the same conditions, the maximum dynamic shear modulus of lime phosphogypsum stabilized soil is much larger than that of plain red clay, and the maximum damping ratio is much smaller than that of plain red clay. The constitutive relationship between the dynamic shear modulus, damping ratio and dynamic shear strain of plain red clay and lime phosphogypsum stabilized red clay conforms to the H-D model. The addition of lime and phosphogypsum can significantly improve the dynamic shear modulus of red clay and reduce the damping ratio. It is indicated that lime phosphogypsum stabilized red clay can improve soil strength, increase soil resistance to dynamic shear deformation and reduce the energy loss. References | Related Articles | Metrics

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Fume Suppression Effect of Asphalt Mixed with Tourmaline Powder and Prediction Model for Fume Production of Its Asphalt Mixture LI Ping1，CHEN Xiule1，WANG Meng1，NIAN Tengfei1，DING Pan2 2023, 42(10): 83-90.  DOI: 10.3969/j.issn.1674-0696.2023.10.11 Abstract ( )   Inhibiting the release of fume during the paving and rolling of hot mix asphalt and asphalt mixtures is of great significance for reducing environmental pollution and reducing the harm to construction personnel hazard. The asphalt fume was collected by the homemade asphalt fume generation and enrichment device, and the fume suppression effect after adding the tourmaline powder to the asphalt was evaluated, which took the smoke suppression rate obtained by the gravimetric method as the evaluation indicator. In addition, the aggregate specific surface area theory-area reduction method was used to establish the fume production rate model of asphalt mixture, and the fume production rate of graded mixtures of AC-13, OGFC-13 and SMA-13 was analyzed. The research results show that with the decrease of the particle size of tourmaline powder and the increase of the content, the penetration of the asphalt decreases, the softening point increases, the ductility shows a trend of increasing firstly and then decreasing and the viscosity increases. The asphalt mixed with tourmaline powder has better fume suppression effect, and the technical performance and fume suppression effect of asphalt are the best when the amount of 10 μm tourmaline powder is 14%. The established model of the fume production rate of the mixture is more effective in predicting the fume production of the mixture in a loose state, and the SMA-13 grading type mixture has the smallest fume production rate. References | Related Articles | Metrics

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Multi-scale Spatial Heterogeneity Analysis of Motorcycle Traffic Accident Severity PAN Yiyong, MIAO Xuanye, WU Jingting 2023, 42(10): 91-99.  DOI: 10.3969/j.issn.1674-0696.2023.10.12 Abstract ( )   To investigate the spatial heterogeneity and degree of factors influencing the severity of motorcycle traffic accidents, a multi-scale geographically weighted regression model was used to analyze. Taking the severity of motorcycle traffic accidents as the dependent variable, the influencing factors were selected from aspects such as people, vehicle, road and environment. The degree of spatial heterogeneity was quantified by use of different bandwidth values of influencing factors. The research results show that the multi-scale geographically weighted regression model can quantify the degree of spatial heterogeneity of different influencing factors. Among the influencing factors with a large degree of spatial heterogeneity, the cloudiness has the greatest degree of spatial heterogeneity, and the fatigue has the least degree of spatial heterogeneity. The effect of vehicle speed is the strongest, while the effect of fatigue is the weakest. In addition, both vehicle speed and T-intersections positively affect the severity of motorcycle traffic accidents. There were positive and negative differences in the regression coefficients for the remaining influencing factors such as cloudiness, the number of vehicles involved and urban areas, which means the positive/negative effect on the severity of motorcycle traffic accidents is related to geographic location. References | Related Articles | Metrics

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Situation Awareness Level Analysis of Forklift Drivers Based on Random Forest Algorithm CHEN Weijiong1, FENG Xiang1, LI Xin2,3, LUO Yabin2, HAN Weijia1 2023, 42(10): 100-108.  DOI: 10.3969/j.issn.1674-0696.2023.10.13 Abstract ( )   The current situation of forklift safety accidents and the safety accidents caused by the lack of situation awareness level of forklift drivers were studied. The characteristic importance of drivers’ eye tracking indicators was predicted based on random forest algorithm, and the correlation law between the situation awareness level, the eye tracking indicators and skin electromyography indicators of forklift drivers was explored. The forklift driver situation awareness measurement experiment under three typical driving test scenarios based on the combination of physiological characteristic indicators and situational awareness rating table (SART) was conducted. The research results demonstrate that there is a linear relationship between the situation awareness level and physiological indicators of forklift drivers, and the construction of physiological indicators can achieve quantitative evaluation of forklift driving safety. The test results can provide data support for forklift drivers to improve their driving safety level and help to improve the training and examination indicators of forklift driver. References | Related Articles | Metrics

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Influence of Illumination at the Entrance of High-Altitude Tunnel on the Psychological State of Drivers WANG Bing, ZHAO Yue, LI Pengsheng, ZHANG Ligai 2023, 42(10): 109-114.  DOI: 10.3969/j.issn.1674-0696.2023.10.14 Abstract ( )   In order to study the effect of the illuminance change of the entrance section of the high-altitude tunnel on the psychological state of the driver, the tunnel real vehicle test was carried out. Firstly, a low-oxygen environment was constructed. Then, the illuminance, heart rate, respiratory rate and other test data were collected by lux meter and physiology instrument, and the tunnel entrance section was divided into five sections according to the degree of physiological stimulation of illumination on the driver, so as to study the physiological change rules of the driver. The drivers psychological state was analyzed through physiological changes. One-way ANOVA was used to test the significance of physiological index data in different segments, and the relationship model between illuminance, heart rate growth rate and respiratory rate was constructed. The results show that there are significant differences in heart rate growth rate and respiratory rate in different sections of tunnel entrance, and the drivers psychological tension was the strongest within the range of 100m in front of the tunnel entrance to 100m inside the entrance. The growth rate of heart rate and respiratory rate firstly increase and then tend to decrease with the increase of illuminance, and both reach a maximum value near the tunnel opening. Drivers in low-oxygen environment have a stronger sense of psychological tension. Through the relationship model, it is found that the psychological tension of drivers in low-oxygen environment is greatly affected by illuminance. References | Related Articles | Metrics

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Velocity Characteristics and Separation Chase Effect in Final Approach GU Runping,DUAN Linbo,WEI Zhiqiang 2023, 42(10): 115-121.  DOI: 10.3969/j.issn.1674-0696.2023.10.15 Abstract ( )   In order to accurately calculate the separation chase effect of the aircraft during the final approach and reduce unnecessary waste of separation, based on the radar record data and QAR data, the speed variation characteristics of the aircraft at the final approach was statistically analyzed and the final approach speed model was established firstly. Secondly, a four-dimensional trajectory prediction model in final approach was established to realize the calculation of aircraft position and altitude at different times. Thirdly, the calculation, analysis and Monte Carlo simulation test on separation chase effect of different aircraft type combinations, required separations, and initial positions of the front and rear aircraft were carried out to analyze the statistical law of separation chase effect. The research results show that when the required minimum separation remains unchanged, the separation chase amount between the front and rear aircraft decreases as the distance between the rear aircraft and the runway threshold decrease, and the required minimum separation is 3nm. The separation chase amount reaches maximum when the rear aircraft is at 18nm from the runway threshold, which is 1.73nm; at the end of the chase, the separation chase amount is the smallest, which is 0nm. The required minimum separation is positively correlated with the separation chase amount. When the required minimum separation is 5nm, and when the rear aircraft chases from 18 nm from the runway threshold to the front aircraft arriving at the runway threshold, the separation chase amount is the largest, which is 2.51nm. The correlation between the required minimum separation and the relative separation chase amount is relatively weak, and when the required minimum interval is 3 nm, 4 nm, and 5 nm, the mean values of relative separation chase amount are all around 50%. References | Related Articles | Metrics

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Resilience of Highway Network Based on Multiple Weighted Center Characteristics LIN Peiqun1，LIU Zihao1，YAN Mingyue2 2023, 42(10): 122-131.  DOI: 10.3969/j.issn.1674-0696.2023.10.16 Abstract ( )   To quantify the impact of traffic closures on highway network connectivity, and fully evaluate network resilience, a highway weighted network was established on the basis of P-space mapping method and incorporating passenger and freight vehicle flow. The centrality index of the weighted network was designed by combining the multi-characteristics gravity model. Considering the interactive flow between districts, the resilience evaluation indicators suitable for weighted networks were furtherly established. Taking the highway network in Guangdong Province as the research object, the resilience of highway network under different closure control scenarios was analyzed. The research results show that: compared with the traditional unweighted center index, the multi-weighted center index based on multi-characteristics gravity model can more effectively identify the core nodes in the highway network, and different neighborhood radii have a certain impact on the identification effect. The resilience evaluation index of integrating interregional vehicle flows can effectively quantify the importance of the core transportation network to the high-speed network. The highway network in Guangdong Province is centered around the Greater Bay Area, with significant traffic aggregation effects in the four cities such as Guangzhou, Shenzhen, Dongguan and Foshan. The closure of Dongguan city, Bao’an district, and Baiyun district has the greatest impact on the connectivity of the highway network. After the traffic closure control of the top 20% core areas represented by these three areas, the proportion of the largest connected subgraphs in high-speed networks and the cumulative loss of global efficiency reach 93.31% and 91.74%, respectively. Therefore, it is of great importance to ensure smooth passage of nodes in the core area. It is also necessary to further improve the highway network planning in undeveloped and marginal areas to improve the overall resilience of the highway network. References | Related Articles | Metrics

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Vehicle and Pedestrian Detection Algorithm Based on Content-Aware Reassembly of Features DENG Tianmin1，LIU Jinfeng1，WANG Chunxia1，LI Qingying2 2023, 42(10): 132-141.  DOI: 10.3969/j.issn.1674-0696.2023.10.17 Abstract ( )   In the autonomous driving scene, a content-aware reassembly of features and adaptive fusion (CRAF-YOLOv5) vehicle and pedestrian detection algorithm was proposed to address the issues of large impact of complex backgrounds on vehicle and pedestrian detection targets and low detection accuracy of small targets. The multi-channel feature extraction network was formed by introducing the channel attention mechanism to enhance the extraction performance of target features in complex background. In the early stage of feature fusion, the up sampling was carried out through content aware reassembly features, and the jump connection structure was added to strengthen the representation ability of shallow network for small target features. In the later stage of feature fusion, the adaptive weight fusion was used to learn features at different scales, which realized the dynamic learning and deep fusion of deep and shallow layer features. The experimental results show that the average mean accuracy of vehicle pedestrian target detection of the proposed method on BDD100K and KITTI datasets reaches 84.40% and 93.35% respectively, which is 3.90% and 0.45% higher than that of the YOLOv5 benchmark algorithm respectively. References | Related Articles | Metrics

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Influence Factor Analysis and Modeling on Taxi-Hailing Behavior Considering Individual Heterogeneity FENG Feiyu1，LI Xinghua2，GUO Yuntao2，YAN Kang1 2023, 42(10): 142-148.  DOI: 10.3969/j.issn.1674-0696.2023.10.18 Abstract ( )   To investigate the underlying mechanisms of changes in travel behavior, a RP survey was conducted in Shanghai, which obtained potential factors affecting the frequency of taxi-hailing usage, such as socio-economic characteristics, commuting characteristics and psychological perception characteristics of commuters. A random parameters ordered Probit model was employed to estimate the impact of relevant variables among these potential influencing factors on taxi-hailing usage frequency and individual heterogeneity, and the key influence factors were analyzed. The results show that the commuters such as young people, middle and upper-income groups, urban residents as well as medium and long-distance commuters who perceive taxi-hailing as cost-effective and safe use taxi-hailing services more frequently. Furthermore, a majority of those who frequently work overtime and those who find taxi-hailing comfortable and convenient also exhibit higher taxi-hailing usage. However, there are still certain groups that use taxi-hailing less frequently, indicating individual heterogeneity within the population. These research findings can provide reference for policy design in urban transportation management and the formulation of strategies for taxi-hailing development. References | Related Articles | Metrics

Transportation Equipment

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Multi-objective Optimization of Motorcycle Multi-link Rear Suspension Hard Point RAN Xiansheng，LI Jinbo，LIU Xingjun，YU Dajiang 2023, 42(10): 149-155.  DOI: 10.3969/j.issn.1674-0696.2023.10.19 Abstract ( )   Aiming at the pitch vibration and vertical vibration problems of motorcycles during driving, an optimization scheme based on the hard point coordinates of the multi-link rear suspension system was proposed. The ride comfort of the motorcycle was improved by optimizing the key hard points of the rear suspension system on the prototype vehicle. A complete motorcycle model was established, and the correctness of the simulation model was verified by road test. The optimization goal was to minimize the RMS value of the pitch acceleration and the RMS value of the vertical weighted acceleration of the body center of mass. Taking the coordinates of the hard points of the multi-link suspension system as design variables, the multi-objective optimization of the multi-link rear suspension system was completed by using the NSGA-Ⅱ genetic algorithm. The results show that after the optimization, the RMS value of the pitch acceleration of the whole vehicle is reduced by 24.0% and the RMS value of the vertical weighted acceleration is reduced by 39.2%, which improves the riding comfort of the motorcycle and has important engineering application value. References | Related Articles | Metrics

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Design and Simulation of Hybrid Electric Propulsion System for Convertiplane DENG Tao1,3,4，TAN Xi2 ，XIONG Zhihao2 ，ZHENG Yuwei2 2023, 42(10): 156-162.  DOI: 10.3969/j.issn.1674-0696.2023.10.20 Abstract ( )   Convertiplane combines the advantages of fixed wing and multi-rotor and has a good prospect in the future aviation industry. According to the characteristics of the power system structure distribution and power demand, the scheme of the incremental hybrid electric propulsion system was proposed. According to the flight dynamics and power demand, the parameters of each component of the power system were matched and selected. Combined with the constant power control strategy, the simulation model of the hybrid electric propulsion system was established and analyzed. The results show that the battery SOC value is finally stable in the range of 0.35~0.45 and the rotor motor and tail rotor motor both operate in the range of parameter matching results, which verifies the rationality of the scheme design and parameter matching of the proposed hybrid electric propulsion system. References | Related Articles | Metrics