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07 October 2023, Volume 42 Issue 9 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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Shear Hysteresis Effect of Butterfly Web Box Girder Based on Equivalent Section Method CHEN Jianbing1, ZHANG Yunfei1,3, LI Xiang2,CAI Xinjiang1 2023, 42(9): 1-10.  DOI: 10.3969/j.issn.1674-0696.2023.09.01 Abstract ( )   PDF (10260KB) ( )   According to the principle of equivalent section, the cross-section at the hollow web of the box girder was treated equivalently, the warpage displacement function under shear deformation of the web was established by considering the equilibrium relationship of its cross-sectional axial force, and the differential equation of the shear hysteresis effect under the equilibrium state of the structure was deduced. Combining with the model test, ABAQUS finite element model and relevant literature values, the longitudinal stress distribution laws of the butterfly web box girder (simply supported) under concentrated load and uniform load were compared and analyzed, and the three-dimensional distribution model of the shear hysteresis coefficient of the whole girder section was obtained. The results show that the longitudinal stress of the butterfly web box girder is distributed in a positive shear hysteresis state under vertical load, and the shear hysteresis effect is larger at the web joints in the pivot section and mid-span section of the box girder. The results of this paper are in good agreement with the experimental values and finite element values under concentrated loads and uniform loads. The relative errors (absolute values) of the two are in the range of 2.00%~2.44%, compared with the literature values. References | Related Articles | Metrics

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Mechanical Performance of 1,000-Meter Level Open-Section Composite Girder Cable-Stayed Bridge with Steel-UHPC Composite Bridge Deck MA Tingting, ZHANG Shishou 2023, 42(9): 11-17.  DOI: 10.3969/j.issn.1674-0696.2023.09.02 Abstract ( )   PDF (1850KB) ( )   In order to overcome the shortcomings of large dead weight and limited spanning capacity for traditional steel-concrete composite girder cable-stayed bridge, and solve the problems of poor fatigue resistance of orthotropic steel decks and damageable pavement for steel girder cable-stayed bridges, the trial design scheme of a 1,000-meter span open-section composite girder cable-stayed bridge with steel-UHPC composite bridge deck was proposed, and the static and wind-resistant performance of the designed bridge was analyzed. The influence rules of the height H and width B of the main girder, the thickness of the top steel plate tsteel, the standard thickness of the UHPC slab tUHPC, the elastic modulus of the concrete EUHPC, and the thickness of the lower flange steel plate tf on the static performance of the composite girder cable-stayed bridge and the main control factors of the design were explored. The results show that the UHPC material greatly improves the compressive and crack strength of the composite bridge deck. The trial design scheme meets the structural static strength requirements, and the use of thinner UHPC slabs can effectively reduce the dead weight of the main girder. The compressive stress of the steel girder is the main control factor for the static design of the girder, and increasing the height of the main girder or the thickness of the lower flange plate of the steel girder can effectively reduce the compressive stress of the steel girder. The 1,000-meter level open-section composite girder cable-stayed bridge with steel-UHPC composite bridge deck can meet the flutter stability requirements for bridge in some regions in China. References | Related Articles | Metrics

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Risk Factors of Railway Bridge and Tunnel Engineering Technology Interface BAO Xueying1, ZHAO Jinxia1, BAN Xinlin2,3, XU Jianchao2,3 2023, 42(9): 18-26.  DOI: 10.3969/j.issn.1674-0696.2023.09.03 Abstract ( )   PDF (4229KB) ( )   In order to clarify the causes and paths of risks in the constructing process and effectively decrease the risk of railroad bridge and tunnel engineering technology interface, the risk factors of bridge and tunnel engineering technology interface were systematically analyzed by using the combination of DEMATEL, ISM and BN. Firstly, the risk factors of technical interface were extracted from three dimensions: physical risk, manager active risk, and environmental risk. Secondly, using the combination method of DEMATEL-ISM and expert knowledge, a hierarchical network model was constructed, which was mapped into BN; and the expert judgment was further transformed into conditional probability distribution to quantify the strength of interdependence between technology interface risk systems and determine the main paths leading to risk occurrence. The research results show that the closest cause path leading to the occurrence of risk is X16 (degree of collaboration between teams) →X8 (unreasonable communication channels and poor information transfer) →X1 (differences in technical parameters and size specifications of different units)→X4 (errors in engineering handover reservation and pre-burial)→X2 (engineering entities which cannot be connected or have spatial location conflicts)→Z, and it is found that the probability of risk occurrence of technical interfaces is higher. References | Related Articles | Metrics

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Friction Coefficient of Ramp Pavement Based on Simulation Software CarSim HUANG Xiaoming1,2, LIU Zeyu1,2, HONG Zhengqiang3 2023, 42(9): 27-35.  DOI: 10.3969/j.issn.1674-0696.2023.09.04 Abstract ( )   PDF (2154KB) ( )   Based on the vehicle dynamics theory, the CarSim simulation software was used to establish a vehicle-road model on the ramp in order to study friction coefficient of the ramp road surface. Two typical driving conditions such as normal driving and braking at different speeds were designed. Three safety indicators were selected to evaluate the driving status of vehicles such as braking distance d, lateral offset distance l, and peak adhesion coefficient μmax, and three comfort indicators were also selected, including lateral acceleration ay and yaw rate ω and the braking deceleration (i.e., longitudinal acceleration) ax. Moreover, the threshold values of each indicator were determined. The safety and comfort analysis were conducted on the driving data of vehicles obtained from the simulation test, and the relationship curve among peak adhesion coefficient μmax, speed V and slope i was obtained. Linear and nonlinear regression analysis methods were used to fit the friction coefficient of ramp μ0, and the fitting formula for the friction coefficient of the ramp road surface based on the binary factor V-i was obtained. The results show that the friction coefficient of the ramp road surface increases with the increase of vehicle speed, and the increment continues to increase, and decreases with the increase of ramp slope and the change amplitude is relatively stable. The fitting formula can accurately predict the friction coefficient of the ramp road surface. References | Related Articles | Metrics

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Influence of Interlayer Continuity Conditions on the Dynamic Characteristics of Asphalt Pavement GAO Yuanyuan1, JIAO Yanpeng2, WANG Peng3, LIU Zhi1 2023, 42(9): 36-41.  DOI: 10.3969/j.issn.1674-0696.2023.09.05 Abstract ( )   PDF (902KB) ( )   Due to the differences in material properties between different structural layers and the limitations of construction technology, the interlayer contact conditions between layers of asphalt pavement structures are not completely continuous during use, but they are still considered fully continuous in the design of asphalt pavement. In order to explore the influence of interlayer contact state on the dynamic characteristics of asphalt pavement, the partial differential equations were firstly transformed into ordinary differential equations by using integral transformation, and a transfer matrix was established and introduced to characterize the interlayer continuous state. Then, based on boundary conditions and two types of integral inverse transformations, an analytical solution for the dynamic response of interlayer non-fully continuous asphalt pavement structures was obtained. Finally, the change in interlayer contact state was simulated through parameter changes, and the impact of interlayer contact state on the dynamic response of the pavement structure was analyzed. The calculation results show that the contact conditions between the surface layer and the base layer have the greatest impact on the calculation results of road surface deflection. Improving the interlayer bonding strength between the surface layer and the base layer can effectively reduce the deflection response of asphalt pavement. References | Related Articles | Metrics

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Effect of Fillers on High Temperature Performance of Waterborne Epoxy Emulsified Asphalt Mortar HUANG Weirong1, XIONG Kelin1, LI Huailong2, WANG Jiao3 2023, 42(9): 42-49.  DOI: 10.3969/j.issn.1674-0696.2023.09.06 Abstract ( )   PDF (4104KB) ( )   To study the effects of fillers and the powder to glue ratio on the high temperature performance of waterborne epoxy emulsified asphalt, and the waterborne epoxy resin system in modified emulsified asphalt, and different fillers and powder to glue ratios of waterborne epoxy emulsified asphalt slurries with drawing test and dynamic shear rheological test (DSR) were used to determine the optimal dosage were prepared. The variation rules of complex modulus (G*), phase angle (δ), rutting factor (G*/sinδ), non-recoverable creep compliance (Jnr) and creep compliance difference rate (Jnr-diff) of asphalt mortar were analyzed by temperature scanning and the repeated creep mode under multiple stresses. And the microstructure of waterborne epoxy emulsified asphalt and two mortars were tested by scanning electron microscope (SEM) in order to study the high temperature rheological properties and principles of asphalt mortar. The research results show that the reasonable content of waterborne epoxy resin system in modified emulsified asphalt is 20%. Cement-waterborne epoxy emulsified asphalt mortar has better high-temperature deformation resistance than mineral powder-waterborne epoxy emulsified asphalt mortar under different temperatures and shear stresses. Jnr of the two types of mortars shows excellent correlation with the powder to glue ratio, and the sensitivity of mineral powder slurry to the powder to glue ratio is higher. Increasing the powder to glue ratio can improve the high-temperature performance of the two mortars. During the process of increasing the powder to glue ratio of mineral powder mortar from 0.3 to 1.2, the high-temperature stability continues to improve. The high-temperature stability of cement mortar has an extreme value when the powder to glue ratio is between 0.9 and 1.2. Mineral powder shows modulus enhancement effect in asphalt mortar. The cement hydration products form a dense structure in the slurry with the curing products of asphalt and water epoxy resin. References | Related Articles | Metrics

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Colloidal System Stability of High Viscosity Modified Asphalt CHENG Zhihao1,2, LIANG Naixing1, ZHANG Yingying2, ZHOU Peiyan2, LI Xiao2 2023, 42(9): 50-56.  DOI: 10.3969/j.issn.1674-0696.2023.09.07 Abstract ( )   PDF (2731KB) ( )   In order to accurately quantify and evaluate the colloidal system stability of high viscosity modified asphalt, the light transmittance and initial flocculation point of different samples at three dilution concentrations were observed by flocculation titration test. The variation rule of flocculation ratio (FR) and dilution of samples (C) as well as the Heithaus parameter of the colloidal structure were analyzed. The insolubility value (IN)and solubility coordination value (SBN) of different sample solutions at the flocculation point were calculated. The results show that the material flocculation ratio (FR) and dilution value C obtained from the transmittance-time curve during the flocculation titration test have a good linear fitting relationship. From the perspective of solubility parameters, it can be demonstrated that using the gelation state index P to comprehensively evaluate the gelation solubility of asphaltene and the gelation ability of soluble substances in the sample has a specific physical characterization significance. With the addition of high viscosity modified materials, the gelation state index P decreases gradually, and the stability of colloidal structure decreases obviously. As the amount of high viscosity modifier increases, the material colloid system gradually tends to become unstable from a relatively stable compatibility state, resulting in asphaltene flocculation or phase separation phenomena. The curve of ΔTR&B and P value with better correlation could be established through experiment results. Based on the current specification requirement that the softening point difference should not exceed 2.5 ℃, the critical solubility index P value corresponding to this kind of high viscosity modified asphalt is 2.876, and the critical dosage for its colloidal system to maintain relative stability is about 6.4%. Flocculation titration method is a quantitative method to evaluate the overall stability of sample colloid system. References | Related Articles | Metrics

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Fatigue Characteristic of Wood Dust-Based Bio-oil Regenerate Aged Asphalt ZHOU Xinxing1,2 2023, 42(9): 57-62.  DOI: 10.3969/j.issn.1674-0696.2023.09.08 Abstract ( )   PDF (1432KB) ( )   In order to analyze the influence of bio-oil prepared from wood dust pyrolysis on the fatigue characteristics of aged asphalt, dynamic shear rheometer (DSR) was used to conduct rheological tests on bio-oil regenerate aged asphalt (BRAA) under stress control mode to evaluate its fatigue characteristics. The corresponding number of shear times when the complex shear modulus decreased to 50% (Nf50), the inflection point of the dissipated energy change rate (Nfm) and the number of cyclic loading times corresponding to the inflection point of the asphalt complex modulus change curve (NfG*) were selected as the evaluation indexes of fatigue performance. The effects of different bio-oil contents, different aging degrees and different stress levels on the fatigue characteristics of BRAA were studied. And the functional group changes of BRAA were also analyzed. The results show that under different testing conditions, the evaluation indexes of fatigue life of BRAA have a consistent ranking, namely NfG*>Nfm>Nf50. The optimal content of bio-oil is ranged from 15% to 20%. Among all evaluation indexes of BRAA, NfG* has the highest and easiest discrimination in evaluating the fatigue performance of recycled asphalt, Nf50 is simple and efficient. Bio-oil can reduce the content of sulfoxide functional groups in the aged asphalt, increase the content of carbonyl functional groups and low wave number fingerprint regions and promote the regeneration of aged asphalt. References | Related Articles | Metrics

Transportation Infrastructure Engineering

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Preparation and Photocatalytic Performance of Nitrogen-Doped Nano-ZnO Supported on Diatomite ZHANG Zhanmei1, 2, REN Xiaoyu1, ZHANG Zhongtian1, ZHANG Li1 2023, 42(9): 63-68.  DOI: 10.3969/j.issn.1674-0696.2023.09.09 Abstract ( )   PDF (5146KB) ( )   Using zinc acetate dihydrate, urea, ammonia and purified diatomite as raw materials, diatomite supported nitrogen-doped nano-zinc oxide catalyst (N-ZnO/DE) was prepared by sol-gel method. The structure, morphology and composition of the samples were characterized and analyzed by use of testing techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible diffuse reflectance spectrometer (UV-Vis DRS) and fluorescence spectrometer (PL). Taking methylene blue (MB) as the target pollutant, the photocatalytic activity and stability of diatomite loaded nitrogen-doped ZnO nanoparticles on MB under visible light irradiation were investigated. The research results show that N-ZnO /DE can effectively broaden the spectral response range and improve photocatalytic efficiency. After 150 min photocatalytic oxidation, the maximum decolorization rate of MB in N-ZnO/DE catalytic reaction system reaches 86%, and the reaction is in accordance with the first-order kinetic model. ·OH and ·O-2 are found to be the main active substances for photocatalytic degradation of MB by the free radical capture experiment, and free radical oxidation is the main pathway for MB decolorization reaction. References | Related Articles | Metrics

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Length of Single Lane Deceleration Lane on Car and Truck Separation Highway PAN Binghong1, LI Chengcai2, GE Ruicheng1, LI Xiang1 2023, 42(9): 69-76.  DOI: 10.3969/j.issn.1674-0696.2023.09.10 Abstract ( )   PDF (4475KB) ( )   When using a dedicated exit for passenger and freight on a car and truck separation highway, the length of the deceleration lane should be different from that of the mixed passenger and freight traffic form due to different types of vehicles on the deceleration lane. Based on the operational data of the vehicles within the exit range measured by the tracking radar, the regression function between the speed of the exiting vehicles and the deceleration distance was constructed and a single lane deceleration lane length calculation model was determined by using the goodness of fit selection method. According to the measured data and the regression function, the values of key parameters in the deceleration lane length calculation model such as deceleration speed, initial speed and running speed of distributing spot were determined. The recommended values of the length of dedicated deceleration lane and the gradual rate were proposed. The research results show that most vehicles within the exit deceleration process are in a uniform deceleration, the starting point of deceleration is the starting point of gradual section, and the deceleration lane is composed of gradual deceleration section and equal width deceleration section. The length of the dedicated deceleration lane for trucks is greater than that of the dedicated deceleration lane for cars. The deceleration lane length specified in China’s regulations basically meets the needs of passenger cars to decelerate when driving out, but it does not meet the required deceleration length for trucks. The departing trucks need to decelerate in advance on the main line. References | Related Articles | Metrics

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Ship Model Test Study on the Influence of Power Station Expansion Project on the Navigation of the Original Ship Lock CAI Chuang1, YANG Shuo1, CAI Xinyong2, HOU Xiangyong1, GONG Liangshuang1 2023, 42(9): 77-84.  DOI: 10.3969/j.issn.1674-0696.2023.09.11 Abstract ( )   PDF (2223KB) ( )   Taking the Xiangjiang River Jinweizhou hub ship lock expansion project as an example, the impact of the expansion project on the navigation flow conditions of the original ship lock was obtained by analyzing the ship model test data before and after the project. The optimization scheme of the expansion project basically eliminated the reflux flow pattern in the upstream approach channel of the first-line ship lock before the project, and reduced the maximum longitudinal and transverse flow in the portal area by 0.23 m/s and 0.82 m/s respectively, compared with those before the project. The maximum navigable flow in the upstream channel entrance area of the first-line ship lock of the hub increases from 6 653 m3/s before the project to 6 963 m3/s in the optimization scheme. The most unfavourable working condition of ship model test is working condition 5 (Q=12 300 m3/s). The ship model navigation effect of the optimized scheme is better than that of the original scheme in whole, and the average navigation speed of the optimized scheme under various flow conditions has increased. When Q<8 200 m3/s, both the maximum rudder angle and maximum drift angle of the upstream and downstream have decreased compared to the original scheme, which optimizes the navigable flow conditions of the channel and greatly improves the safety factors of passing ships, but still slightly higher than that before the project. References | Related Articles | Metrics

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Urban Transportation Carbon Emission Prediction Model and Carbon Reduction Strategies XIAO Hong1, DENG Zihao1, REN Yanjuan2, REN Xiaohong1 2023, 42(9): 85-92.  DOI: 10.3969/j.issn.1674-0696.2023.09.12 Abstract ( )   PDF (5201KB) ( )   Transportation is a large energy-consuming industry in China and it has become one of the major sources of carbon emissions. Firstly, the causal relationship between transportation and economics, energy and environmental subsystems was analyzed and then a system dynamics model of transportation carbon emissions was established. Taking Chongqing as the research background, carbon emission reduction strategies for the transportation industry were proposed by optimizing industry and energy structures, reforming transportation structures and improving indicators of energy-saving and emission reduction technologies. Vensim software was used to simulate the implementation effects of different transportation emission reduction governance strategies. References | Related Articles | Metrics

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Influencing Factors of Traffic Accident Severity Based on Optimized CART ZHANG Mengmeng, LI Zewen, XU Yunfan, LIU Yongdong 2023, 42(9): 93-98.  DOI: 10.3969/j.issn.1674-0696.2023.09.13 Abstract ( )   PDF (1017KB) ( )   In order to deeply analyze the influencing factors of traffic accident severity and realize the active prevention and accurate prevention and control of traffic accidents, the factors with high significance in the attributes such as vehicle, road and environment were selected as the input variables and the accident severity was taken as the secondary classification output variable. The CART decision tree model of the influencing factors of traffic accident severity was established and the CCP algorithm was selected to optimize and solve the proposed model. The relative error value, ROC curve and AUC were selected as evaluation indexes to verify the effectiveness of the proposed model. The relative error value of the proposed model was only 6.08% and the AUC value was 0.91. The research results show that in terms of road and traffic environment, the factors such as bad weather, collapsed pavement, hidden dangers in the road and no signal control at the intersection have a great impact on the severity of traffic accidents; in terms of vehicles, the probability of major accidents or above of large trucks is 4 times that of other vehicles. Therefore, the above factors should be the focus of traffic accident prevention and control. References | Related Articles | Metrics

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Multi-objective Tourism Route Planning under Regular Epidemic Prevention and Control WANG Weili, ZOU Xueer 2023, 42(9): 99-105.  DOI: 10.3969/j.issn.1674-0696.2023.09.14 Abstract ( )   PDF (2630KB) ( )   Under regular epidemic prevention and control, reservation policies at popular scenic spots are subject to the requirements of “limited quantity, reservation and staggered peak”. At the same time, the sporadic outbreaks throughout the country may cause the temporary closure of some scenic spots. Tourists need to pay attention to relevant information and adjust their tourism routes in time. Therefore, a personalized tourism route planning method for tourists was proposed, comprehensively considering the factors of epidemic prevention and control. Firstly, by obtaining information about tourist attractions and user comments on them, a rating mechanism for tourist attractions was designed considering the impact of attraction popularity and its opening time on tourist travel experience, a tourism route planning model with the objective function of minimizing time and cost was established. Then, the road network data was obtained through the Gaode Map open platform and an improved ant colony algorithm was designed for solution. Finally, taking the scenic spots in Shanghai as an example, a variety of travel scenarios under regular epidemic prevention and control were built, and the optimal travel routes in each scenario was obtained. Research results demonstrate that the proposed tourism route planning method takes into account the impact of epidemic prevention and control, which can effectively reduce users travel time and travel cost. The proposed method has good practicability, which can provide reference for the planning of relevant tourism products. References | Related Articles | Metrics

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Fixed Time Cooperative Control of Straddle Monorail Intelligent Marshalling LIU Chaotao1, LIU Haoming1, DU Zixue1, WU Haoxin2, HOU Zhongwei2 2023, 42(9): 106-112.  DOI: 10.3969/j.issn.1674-0696.2023.09.15 Abstract ( )   PDF (1839KB) ( )   Focusing on the cooperative control of straddle type monorail intelligent marshalling, on the basis of analyzing the operation scenario of intelligent marshalling, the dynamic model was established. The control objectives were clarified, the distributed fixed time cooperative control architecture of straddle type monorail intelligent marshalling was constructed, and the distributed fixed time cooperative control method was proposed. The topological relationship of intelligent marshalling communication was constructed by using algebraic graph theory. The distributed fixed time sliding mode estimator was applied, and the distributed fixed time integral sliding mode controller was designed. Based on Lyapunov stability theory, the stability of the estimator and controller was proved. The numerical simulation results show that the designed distributed fixed time cooperative control algorithm can make the position and speed of intelligent marshalling vehicles track the command curve in 11.5, 13, 12 and 14 s respectively and keep the ideal distance between vehicles, while the intelligent marshalling vehicles with finite time controller can track the command curve in 17, 26, 18 and 28 s respectively. Numerical simulation results show that the designed distributed fixed time cooperative control method can effectively improve the operation efficiency of straddle monorail intelligent marshalling. References | Related Articles | Metrics

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Importance Evaluation of Wuhan Rail Transit Nodes Based on Improved TOPSIS Method TU Min, HAN Yumeng 2023, 42(9): 113-121.  DOI: 10.3969/j.issn.1674-0696.2023.09.16 Abstract ( )   PDF (807KB) ( )   With the consistent development of urban rail transit, how to dig out important sites quickly and effectively is of great significance for the safe operation of rail transit. Taking Wuhan urban rail transit at the end of 2021 as the research object, the Space-L method was used to construct the topological structure of the Wuhan subway network, which considered the local environment of the node and its global attributes in the network, as well as introduced the PageRank algorithm for webpage ranking. The impact of passenger flow on subway stations was analyzed, and the problem of node importance ranking was solved by replacing the traditional TOPSIS method with the cosine similarity TOPSIS method. The results show that: the rail transit network of Wuhan is a scale-free network, and the entire Wuhan rail transit line presents a pattern of small loop line and long radiation. Too long radiation will cause long-distance commuting radiation to over-rely on the transfer of the city center, which is easy to cause the imbalance of passenger flow. The stations with the highest importance ranking in Wuhans rail transit network have more neighboring nodes, relatively centralized locations, larger passenger flow, and higher local and global importance. Compared with the evaluation results of a single indicator, the proposed method is more comprehensive and objective in assigning weights to different attribute indicators, which makes the evaluation more comprehensive and to some extent improves the reverse order phenomenon caused by the failure of Euclidean distance. References | Related Articles | Metrics

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Delay Prediction Method of Transit Flight Based on Ground Guarantee Process YANG Zhao1, CHEN Yixin2, ZHANG Zhijie2 2023, 42(9): 122-129.  DOI: 10.3969/j.issn.1674-0696.2023.09.17 Abstract ( )   PDF (5063KB) ( )   At present, civil aviation flights continue to operate at a high level, and the airport, air traffic control and airline companies participate in the flight transit at the same time. The airport ground support system operates at full load during peak hours, and the flight punctuality rate is difficult to improve. In order to perceive the delays caused by multi-process cooperation during ground support for transit flights in advance, aiming at the relevant characteristics of flight operation process nodes, the flight delay prediction method based on the ground guarantee process for transit flights was proposed. The flight guarantee process was constructed as a graph convolutional neural network structure, the processed time features on each process node were used as the node features of the graph neural network. For the node features on the graph, a variety of aggregation delivery methods were used and integrated to improve the accuracy of flight delay prediction. The results show that, compared with the comparison methods, the average prediction error of the proposed flight delay prediction method is reduced to 7.11 minutes, which has better generalization ability. References | Related Articles | Metrics

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Forecast of Cargo Throughput in Port Based on Improved Grey Markov DING Tianming, PAN Ning, DU Baisong, AI Wanzheng 2023, 42(9): 130-136.  DOI: 10.3969/j.issn.1674-0696.2023.09.18 Abstract ( )   PDF (710KB) ( )   In order to improve the prediction accuracy of port cargo throughput, the grey Markov combination prediction model was optimized and studied by taking Ningbo Zhoushan Port as an example. Firstly, the grey GM (1,1) model was established by using the historical data of the cargo throughput of Ningbo Zhoushan Port in the China Statistical Yearbook. Secondly, the simulated error value was corrected with a first-order Markov chain and the transition state of the error was determined, and a composite grey Markov model was established. Finally, the particle swarm optimization algorithm was used to iteratively optimize and improve the composite model, which enables the proposed model to analyze and calculate each gray interval according to the actual situation, dynamically update its interval parameters in real time and ultimately improve the error accuracy of the improved model. The results show that the mean error of the grey Markov model improved by particle swarm optimization has decreased by 37%, and the predicted value has a higher fit with the actual value, making the predicted results more in line with the actual situation. References | Related Articles | Metrics

Transportation Equipment

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Dynamic Characteristics of Rail Vehicle under Thermal Deformation of Long-Span Cable-Stayed Bridge CHEN Zhaowei1, LONG Quanming1, PU Qianhua1, SHANG Ting2 2023, 42(9): 137-144.  DOI: 10.3969/j.issn.1674-0696.2023.09.19 Abstract ( )   PDF (7615KB) ( )   In order to study the influence of thermal deformation of long-span cable-stayed bridge on the dynamic characteristics of rail vehicles on the bridge, based on the theory of vehicle-track coupling dynamics, the rigid flexible coupling dynamic model of rail vehicle-track-long-span cable-stayed bridge was established by using finite element method and multi-rigid body dynamics. With the help of the proposed model, firstly, the deformation law of long-span cable-stayed bridge under the rise and fall condition of overall temperature was analyzed; then, the comprehensive effect of track random irregularity and rail deformation under temperature load was considered to study the dynamic characteristics of rail vehicles crossing the bridge; finally, the influence law of temperature load and speed on various dynamic indexes of vehicles was studied. The research results show that the long-span cable-stayed bridge deforms under the action of temperature load, and the overall performance is as follows: heating up and bending down, cooling down and arching up, and the deformation changes almost linearly with the temperature load. According to the studied parameters, the rail deformation caused by temperature load increases the wheel rail vertical force, vehicle derailment coefficient and wheel load reduction rate by 1.5%, 3.1% and 5% respectively. The vertical acceleration of the vehicle body decreases by 2.4% under the cooling condition and increases by 3.7% under the heating condition. The main frequency of the vertical acceleration of the vehicle body under the rising and falling temperature conditions is mainly concentrated in the range from 0 to 5 Hz, whose difference is very small compared to normal temperature conditions. The derailment coefficient and vertical acceleration of vehicle body are more affected by temperature load, and the wheel load reduction rate and wheel rail vertical force are more affected by speed. The conclusion provides a certain reference for subsequent scholars to study the influence of temperature load on the dynamic response of vehicles on long-span cable-stayed bridges. References | Related Articles | Metrics

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Analysis and Test of Energy Consumption Characteristics of the Vehicle in Pulse and Gliding Process CHU Jiangwei, HU Pan, LI Honggang, LI Hong, AI Xifeng 2023, 42(9): 145-154.  DOI: 10.3969/j.issn.1674-0696.2023.09.20 Abstract ( )   PDF (5716KB) ( )   In order to study the energy consumption characteristics of the vehicle in the pulse and gliding (Pulse and Gliding, PnG) operation state, the energy consumption related characteristic indexes such as the transient energy saving ΔQ(t), the unit mileage energy saving Δqs(t) and the energy saving rate η under PnG motion state were defined, taking the same distance traveled in the PnG state and uniform velocity operation state as the precondition. The energy consumption indexes under periodic symmetry and asymmetric speed regulation were simulated and analyzed by use of Matlab with different motion state parameters such as desired velocity, acceleration and velocity fluctuation amplitude. The results show that the energy consumption indexes vary with the motion state parameters under different settings. At the same desired velocity, the average transient maximum fuel saving rate measured in the test (37.30%) is smaller than the average transient maximum energy saving rate analyzed in the theory (40.75%). Therefore, the energy saving effect produced by the vehicle motion state control also needs to be guaranteed by the improvement of the energy conversion efficiency of the vehicle power unit and by the optimization of the matching working point or range of the transmission system. The above research results can provide a theoretical basis for achieving energy-efficient operation through vehicle motion state control and provide guidance for vehicle energy-efficient driving practice. References | Related Articles | Metrics