Archive

25 December 2023, Volume 42 Issue 12 Previous Issue   
---
Transportation+Big Data & Artificial Intelligence
Transportation Infrastructure Engineering
Transportation Equipment


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Transportation+Big Data & Artificial Intelligence

Select

Shear Lag Effect of Wide Separated Double-Sided Steel Box Composite Girder Cable-Stayed Bridge YU Xiangmin1, LIU Jin1, DU Xiaoqing1,2, NI Zheng3 2023, 42(12): 1-8.  DOI: 10.3969/j.issn.1674-0696.2023.12.01 Abstract ( )   PDF (4874KB) ( )   In order to meet the increasing traffic demand, in recent years, large-span cable-stayed bridges have begun to use separated double-sided steel box composite beams with large deck width, high lateral stiffness and good wind resistance. Taking the extra-wide separated double-sided steel box composite girder cable-stayed bridge with a girder width of 45.9m as the background project, a three-dimensional member system model and a refined segment model were established by using MIDAS and ANSYS respectively, to study the shear lag effect during the completion stage and construction process of the bridge. The influence of the steel main girder plate thickness on shear lag effect was also analyzed through the sensitivity analysis. The results indicate that in the completed bridge state, the variation range of shear lag coefficients at the bottom and top of the concrete slab is 2.152~2.762 and 1.262~2.024, respectively. The closer to the mid-span section, the greater the shear lag coefficient of the concrete slab. The concrete slab exhibits a significant positive shear lag effect at the position of webs and small stringers, while mainly shows a negative shear lag effect at the position of diaphragms. The shear lag effect at both ends of the concrete slab is most prominent due to the influence of the horizontal component force of the stay cable. During the construction, the shear lag coefficients of the bottom and top of the concrete slabs range from 3.978 to 4.188 and 1.186 to 1.301, respectively. It is necessary to focus on the shear lag effect at the bottom of the slab. The construction steps have a significant impact on the shear lag effect of the concrete slab in the composite girder, particularly the installation of the steel main girder. When the thickness of the steel main girder changes, the variation pattern of the shear lag coefficient is similar. It is recommended to use a thickness of 20~30 mm for the top plate and 15~20 mm for the bottom plate of the steel main girder. References | Related Articles | Metrics

Select

Synthetic Evaluation Method of Bridge Based on BWM and Fuzzy Theory LI Yunyu1, ZHANG Zhicheng2, CHEN Jinzhou3, PENG Hanxian2 2023, 42(12): 9-14.  DOI: 10.3969/j.issn.1674-0696.2023.12.02 Abstract ( )   PDF (1384KB) ( )   Taking the state of the bridge structure and its various parts as the evaluation object, a low-level function with membership degree as the evaluation index was established based on fuzzy theory, and the model was comprehensively evaluated by using the BWM (best worst method) method as a hierarchical weight evaluation means. Using a bottom-up and step-by-step transmission method, the bottom level vector was combined with the indicator weights determined by the BWM method at each level, and the indicators at each level were evaluated layer by layer. Finally, the comprehensive evaluation level of the bridge was determined. According to the comprehensive evaluation level, the priority order of reinforcement for each part of the bridge was determined. Finally, a comprehensive state evaluation of Dingjia Bridge was conducted as an example, and suggestions for reinforcement priority order were given. References | Related Articles | Metrics

Select

Non-uniform Shrinkage Creep Effect of PC T-Beam Bridge WANG Long, WU Xiaoguang, ZHANG Liuyu, MO Di 2023, 42(12): 15-22.  DOI: 10.3969/j.issn.1674-0696.2023.12.03 Abstract ( )   PDF (2190KB) ( )   In order to analyze the non-uniform shrinkage creep effect of PC T-beams under dry conditions and mixed reinforcement conditions accurately, and to master the law of deformation, cross-section stress and cross-section stress redistribution of beam body, a beam element analysis method for PC beam bridges with non-uniform shrinkage creep effect was proposed. Firstly, the cross-section humidity distribution of the T-beam was analyzed through finite element program. Then, the cross-section of the PC beam with similar humidity distribution law was divided into several fiber beam elements, and the calculation of non-uniform shrinkage creep of the cross-section was simplified by the average relative humidity of the fibers. Finally, combined the fiber beam element with the micro-prestressed solidification (MPS) theory, the effects of mixed reinforcement and prestress relaxation were introduced, and the nonlinear incremental scheme finite element theory was used to solve the problem. The research results show that the PC T-beam exhibits significant non-uniform shrinkage creep effects, the average relative humidity has good representativeness, and the drying condition has a great influence on the deflection and stress distribution law of the beam body. At 1000d, the compressive stress reserve of web is lower than that of the top plate and horseshoe, and the difference in normal stress of the same cross-section in the mid span area reaches 3~4 MPa. The characteristics of vertical cracks in mid-span web of T-beam are consistent with those of the weak stress zone of web, which is an important cause of such cracks and should be considered in the design. References | Related Articles | Metrics

Select

Evolution Law of Axial Compression Performance of Concrete Filled GFRP Tube Column under Sulfate Environment JIN Qingping, WANG Yue, ZHAO Tiantian, LIU Yundie 2023, 42(12): 23-30.  DOI: 10.3969/j.issn.1674-0696.2023.12.04 Abstract ( )   PDF (3757KB) ( )   Long-term sulfate corrosion can cause the degradation of concrete structure, and the composite structure of fiber reinforced polymer (FRP) and concrete has good corrosion resistance. The corrosion tests were carried out for short concrete filled GFRP tube columns by sulfate immersion and dry-wet cycle. Through apparent phenomenon observation, mass loss measurement and ultrasonic detection etc., the structure changes of composite columns under the action of sulfate were studied. The ultimate bearing capacity and load-strain curves were tested by axial compression tests, and the evolution law of axial compression performance of short concrete filled GFRP tube columns was compared and analyzed. The results show that in the sulfate environment, GFRP tube can resist sulfate erosion, effectively protecting concrete and ensuring the compressive strength of composite columns. The strength and ductility of short concrete filled GFRP tube columns are reduced by sulfate immersion and dry-wet cycle. Moreover, with the increase of corrosion time, the sulfate dry-wet cycle action causes more defects on the short concrete filled GFRP tube column than the sulfate immersion action does, and the synergistic effect between GFRP tube and concrete is slightly reduced. References | Related Articles | Metrics

Select

Evolution Laws of Asphalt Surface Texture Based on Indoor Wear Test YU Miao1，ZENG Junsen1，LUO Yansheng2，LONG Chengliang3，CHEN Geng1 2023, 42(12): 31-36.  DOI: 10.3969/j.issn.1674-0696.2023.12.05 Abstract ( )   PDF (1349KB) ( )   Traffic volume has a significant influence on the attenuation of skid resistance performance and texture evolution of the pavement in service. In order to study the evolution law of cumulative traffic volume on asphalt pavement surface texture, laser profilometer was used to collect the macro and micro textures of various types of pavement firstly, the corresponding characterization parameters were selected to calculate and the correlation analysis on various texture characterization parameters was carried out. After eliminating multiple linear relationships, RMPD，Rsk，Rku and RSBI were selected as the evaluation indicators of pavement skid resistance performance. Then, based on the tire-pavement dynamic friction analyzer (TDFA) independently developed and debugged by the research group, different traffic volumes were simulated. TDFA was used to carry out wear test to investigate the evolution of pavement surface texture parameters under different traffic volumes. The research results show that under the effect of traffic wear, the earlier the interval of heavy traffic appears, the more severe the wear on asphalt pavement will be caused by texture parameters. However, heavy traffic in the middle and later stages has relatively little impact on the skid resistance of asphalt pavement. References | Related Articles | Metrics

Select

Viscosity-Temperature Characteristics and Modification Mechanism of Straw Modified Asphalt Mortar DONG Juan1, SI Youxiang2, XIE Wei3, ZHANG Ke2,3, ZHANG Yi3 2023, 42(12): 37-44.  DOI: 10.3969/j.issn.1674-0696.2023.12.06 Abstract ( )   PDF (4245KB) ( )   To explore the viscosity-temperature characteristics and modification mechanism of the straw modified asphalt, the Brookfield rotation viscosity test on the straw modified asphalt mortar was firstly carried out to analyze the influence of straw content and type on the viscosity of the modified asphalt mortar, and the temperature sensitivity index was also calculated. Secondly, the infrared spectral characteristics of three kinds of straw modified asphalt mortar were discussed and the relationship between functional group index and viscosity-temperature characteristics of straw modified asphalt was explored. Finally, combined with the microstructure characteristics of the straw modified asphalt, the influence mechanism of straw on base asphalt was revealed. The research shows that the addition of straw fiber increases the viscosity of asphalt. Among them, the viscosity increasing effect of rice straw is better than that of corn straw and wheat straw, and the viscosity decreases with the increase of temperature. No new functional groups are generated in the infrared spectra of the three types of straw modified asphalt mortar, and the addition of straw mainly relies on its physical bonding with asphalt to exert its effect. The amount of straw content affects the distribution of straw inside the asphalt. When the content of straw is 5%, the straw fibers overlap each other to form a network strengthening structure, and at this time, the straw fibers have the best “reinforcement” effect on asphalt. The research results can provide relevant reference basis for the research and development of modified asphalt pavement materials. References | Related Articles | Metrics

Select

Influence of Ultraviolet Aging on High-Temperature Properties of Waterborne Epoxy-SBR Emulsified Asphalt HE Lihong1, YANG Ke1,2, MA Yuefan1,2, WEN Xianxian1,3, LI Qinglin1 2023, 42(12): 45-52.  DOI: 10.3969/j.issn.1674-0696.2023.12.07 Abstract ( )   PDF (2278KB) ( )   The high-temperature properties of waterborne epoxy-SBR emulsified asphalt (WESEA) after ultraviolet aging was investigated by indoor accelerated ultraviolet light aging test. The variation law of surface morphology, high-temperature rheological properties and creep properties of WESEA binder after UV aging was explored, and the changes of WESEA binder functional groups before and after ultraviolet light aging were analyzed through infrared spectroscopy. The results show that as the content of waterborne epoxy increases, the complex shear modulus G*, rutting factor (G*/sinδ), and average elastic recovery rate γrec of the original WESEA binder and the binder after different durations of UV aging all show an increasing trend. The phase angle δ and irrecoverable creep compliance Jnr decreases, and the complex shear modulus aging index G*AI is greater than 1, indicating that waterborne epoxy increases the elastic composition of WESEA binder, effectively improves the high-temperature rheological properties of binder, and enhances the shear deformation resistance of binder. After the same UV aging duration, the functional group aging index CI′ (carbonyl C=O) and SI′(sulfoxide S=O) of WESEA binder decrease with the increase of waterborne epoxy content, but BI′ (butadienyl C=C) is similar, indicating that waterborne epoxy can effectively inhibit the oxidation reaction of the matrix asphalt and degradation of SBR latex in WESEA binder, consequently delay the UV aging process of the WESEA binder. Therefore, waterborne epoxy can effectively improve the high-temperature performance of bonding materials against UV aging. References | Related Articles | Metrics

Select

Feasibility of Using GCL for Regulating Road Subgrade Moisture Field and Optimization of the Installation Position LIU Zhibin1,2，WANG Yuting1,2，LUO Tingyi3，TANG Yasen3，XIE Shiping4 2023, 42(12): 53-60.  DOI: 10.3969/j.issn.1674-0696.2023.12.08 Abstract ( )   PDF (1235KB) ( )   In order to optimize the regulation and layout of the moisture field of the subgrade soil, based on the migration law of the moisture field in the subgrade, the influencing factors of GCL in the subgrade of the moisture field in the subgrade were studied systematically. The water-proof performance of GCL was verified through laboratory model tests, that is, blocking capillary water rise and preventing rainfall water infiltration. Then, based on the law of water migration in unsaturated soil subgrade, numerical simulation methods were used to optimize the placement of GCL in the subgrade. The finite element method was used to compare the effects of the burial depth and number of layers of GCL in the subgrade soil on the subgrade moisture field at the field scale. The results show that GCL has a very important anti-seepage effect. Under single-layer burial condition, placing GCL 1.0 m below the ground can effectively regulate the moisture field. The volumetric moisture content of the subgrade soil within a range of 0.3 m above and below the GCL can quickly reach a stable state and low value. The effect of double-layer GCL installation is not much different from that of single-layer GCL installation. References | Related Articles | Metrics

Transportation Infrastructure Engineering

Select

Experimental Study on Dredged Sediment Solidified with Magnesium Oxide-Desulfurization Gypsum-Steel Slag KONG Xianghui1，LIANG Yunpeng1，ZHANG Jingang2，WANG Xiaokang1，ZHANG Fengrong1 2023, 42(12): 61-69.  DOI: 10.3969/j.issn.1674-0696.2023.12.09 Abstract ( )   PDF (6435KB) ( )   Activated magnesium oxide (MgO), desulfurization gypsum (DG) and steel slag (SS) were used for solidification treatment of dredged sediment. The main factors affecting the strength of solidified sediment, the optimum content of solidified materials and the microscopic solidification mechanism were studied through the single-doping test, response surface test and microscopic characteristics test. The test results show that the single-doped solidification effect of MgO is the most significant, followed by DG, and the single-doped solidification effect of SS is the poorest. The strength of MgO solidified soil increases rapidly in the first 7 days, while that of DG solidified soil grows gently with age. While the strength of SS solidified soil mainly increases in the later curing period due to the slow hydration reaction. According to the response surface test, the interaction between MgO-DG and DG-SS is significant, and the optimum content of MgO, DG and SS in the solidified sediment is 7.62%, 11.31% and 5.80%, respectively. Through the XRD and SEM analysis, it is found that the hydration reaction in the MgO-DG-SS composite cementing system is mutually promoted, and the encapsulation, cementation and filling effect of hydration products make the soil microstructure more compact and stable. Based on the test results, a microscopic mechanism model of MgO-DG-SS solidified sediment is proposed. References | Related Articles | Metrics

Select

Hydrological Effect of In-situ Soil on Road Bioretention Facilities LIU Yan1, PAN Junkui2 2023, 42(12): 70-75.  DOI: 10.3969/j.issn.1674-0696.2023.12.10 Abstract ( )   PDF (2005KB) ( )   As a rainwater runoff control technology, bioretention facilities play an important role in restoring regional hydrological cycle. However, due to the differences in underground soil quality in different regions, the operational effectiveness of bioretention facilities will be affected differently. The water transport process of bioretention facilities under a single rainfall event was studied by the VADOSE/W model. The influence characteristics of four in-situ soil types such as silt loam, loam, sandy clay loam and sandy loam on the surface ponding, underdrain outflow, exfiltration and runoff regulation effects of bioretention facilities were studied. The research results show that when bioretention facilities are not equipped with an underdrain and the permeability coefficient of in-situ soil is relatively small, it is easy to prolong the surface ponding time and increase the overflow water amount. The underdrain outflow in bioretention facilities is significantly affected by the in-situ soil. With the decrease of the permeability coefficient of in-soil, the outflow peak value of underdrain increases and the outflow duration is prolonged. The exfiltration of bioretention facilities is dominated by bottom seepage, the amount of exfiltration volume per unit area can reach 2.78~7.82 times that of lateral seepage, and as the in-situ soil permeability coefficient increases, the exfiltration volume at the bottom correspondingly increases. With the increase of in-situ soil permeability coefficient, the reduction rate of runoff, the reduction rate of runoff peak and the delay time of runoff production of bioretention facilities are all relatively increased. References | Related Articles | Metrics

Select

Discharge Coefficient in Landslide Dam Failure Process Based on Surface Velocity LIU Jie1, CHENG Jing2 2023, 42(12): 76-82.  DOI: 10.3969/j.issn.1674-0696.2023.12.11 Abstract ( )   PDF (2976KB) ( )   In order to determine the range of discharge coefficient values during the dam break process of a landslide dam, based on the water flow surface velocity, a formula for estimating dam-break discharge was proposed, five sets of flume experiments were conducted and the mathematical regression method was utilized to study the flow coefficient during the dam failure process of the dam. The research results show that the longitudinal development of the breach is primarily characterized by layered scouring, with the inclination angle of the scouring surface gradually decreasing and the scouring rate firstly increasing and then decreasing. The discharge of the breach is influenced by multiple factors, such as the height of the dam body and the ratio of the dam body's height to the thickness along the direction of water flow at the bottom. The novel approach of estimating the breach discharge based on surface flow velocity is found to be feasible and highly accurate, with the coefficient Cd of the new outflow formula ranging from 0.19 to 0.43. References | Related Articles | Metrics

Select

An Improved Control Model of Bus Signal Priority Strategy Considering Real-Time Number of Passengers LI Shuqing1, JIANG Yuyang2, GAO Mingyi1, BIN Ke3, CHEN Hao1 2023, 42(12): 83-91.  DOI: 10.3969/j.issn.1674-0696.2023.12.12 Abstract ( )   PDF (1694KB) ( )   Traditional bus signal priority is generally based on the moment of bus arrival at the intersection or the fixed passenger capacity of the bus, and it cannot exactly reflect the actual number of passengers of the bus. To address the problem, an intersection bus signal priority control model was established, considering the real-time number of passengers of the bus, with the minimum delay per person for all people passing through the intersection as the optimization objective. The bus IC card and GPS data were matched, the number of passengers boarding at bus stops was compared, the number of passengers getting off at bus stops was calculated and the real-time number of passengers of buses passing through the intersection was analyzed. The bus signal priority improvement strategy was proposed, and the delay of each phase under the proposed strategy was analyzed by introducing the bus priority intensity coefficient. The intersection per capita delay model and bus signal priority control model were constructed, and the heuristic search algorithm was used to solve the above model. The research results show that compared with the traditional bus signal priority strategy, the bus signal priority strategy considering the real-time number of passengers for improving green light extension and green light early start has reduced the cycle delay per capita by 20.98% and 18.11%, respectively. References | Related Articles | Metrics

Select

Operation Efficiency Measurement of Urban Rail Transit System with Three-Stage DEA-Tobit Model WANG Yonggang, LUO Xianyu, CHEN Junxian, MA Chaoqun 2023, 42(12): 92-98.  DOI: 10.3969/j.issn.1674-0696.2023.12.13 Abstract ( )   PDF (553KB) ( )   Taking 26 typical cities in China as samples, based on the influence of environmental variables and random disturbance factors, a three-stage DEA-Tobit model was used to carry out empirical analysis on the measurement of urban rail transit operational efficiency. The research results show that there is a significant correlation between the operational efficiency of urban rail transit and factors such as system scale, structure, number of transfer stations and network conditions. At present, the rail transit in most cities in China is in the stage of increasing scale benefit, and its resource allocation capacity is already relatively good, but the scale efficiency is insufficient, resulting in low operational efficiency. After adjusting the environmental variables and random disturbance factors, the pure technical efficiency of urban rail transit system will rise, while the scale efficiency will decrease significantly, which is especially evident in cities focusing on the development of low-capacity systems. It is indicated that the control and coordination of the external operating environment can effectively improve the operational efficiency of urban rail transit systems. References | Related Articles | Metrics

Select

Finite-Time Equilibrium in Urban Bus Networks ZHANG Chunmei, LI Ran, YANG Hui 2023, 42(12): 99-105.  DOI: 10.3969/j.issn.1674-0696.2023.12.14 Abstract ( )   PDF (1080KB) ( )   The finite-time synchronization of complex networks was used to study the finite-time equilibrium problem of stochastic urban bus networks. Due to that the urban bus network was a typical complex network and based on the concept of driving-response systems in complex networks, the global Lyapunov function was indirectly constructed by using graph-theoretic method. The driving system represented the balanced operation of the urban bus network in an ideal state, while the response system represented the actual operation of the urban bus network. Then, the synchronization of driving system and response system was realized in a finite time, which was combined with finite-time control strategy and stability theory. Therefore, in the urban bus network, through appropriate traffic scheduling, the network subjected to random interference could achieve consistency with the operation state of the ideal state (balanced operation) network in a finite time. In other words, the urban bus networks affected by stochastic disturbance could restore the balance operation in finite time. Finally, numerical example was used to verify the validity and feasibility of the theoretical results, in which the Chua system was used as the vertex system and the small-world network was used to describe the urban bus networks. References | Related Articles | Metrics

Select

Ride Sharing Optimization Based on Stable Matching PENG Zixuan1，WEI Ran1，SHAN Wenxuan2，WANG Wensi2，GUO Zhen2，CAI Wanjun3 2023, 42(12): 106-112.  DOI: 10.3969/j.issn.1674-0696.2023.12.15 Abstract ( )   PDF (1322KB) ( )   The choice preferences of passengers and drivers are one of the key influencing factors on the matching rate of ride-sharing services. Based on the selection preferences of passengers towards passengers and drivers, as well as the selection preferences of drivers towards passengers, a many-to-one stable matching model that embedded the mutual influence effect of passenger sharing was constructed. Based on the idea of DA (deferred acceptance) algorithm, a many-to-one stable matching algorithm that considered the internal preferences over the same party participants was deigned. The proposed model and algorithm were verified and analyzed through numerical examples. The results show that the matching rate of passengers with the relaxed time window increases by 18%, and the proportion of passengers sharing a ride also increases by 21%, averagely. Meanwhile, with high demand, the matching rate of drivers has increased, the proportion of passengers sharing a ride has significantly increased, and the income of drivers has also increased correspondingly. References | Related Articles | Metrics

Select

Influencing Factors Analysis of Vehicle Conflict Risk Based on Random Parameter Logit Model WEN Huiying，CHENG Jie，ZHAO Sheng 2023, 42(12): 113-120.  DOI: 10.3969/j.issn.1674-0696.2023.12.16 Abstract ( )   PDF (475KB) ( )   In order to more thoroughly explore the influencing factors of highway vehicle conflict risk, both micro and macro factors were taken into account to analyze the possible heterogeneity in them. A random parameter Logit model was established to analyze. Using high-resolution vehicle trajectory data and time to collision (TTC) as the risk identification criterion, the data within 1 second before the occurrence of risk were extracted and processed to obtain three types of characteristics such as the vehicles own motion state, micro interaction with surrounding vehicles and macro traffic flow state on the road section. The features were filtered by using the Pearson correlation coefficient and embedding method. Then, a random parameter Logit model and a random parameter Logit model considering mean heterogeneity were constructed and compared by using the filtered features as model independent factors and the occurrence of vehicle conflict risk as model dependent variables. The research results show that the random parameter model considering mean heterogeneity has the best fitting result, and all three types of variables have significant effect on the conflict risk. The fluctuation of the vehicles own motion state and the speed difference between the vehicle and the vehicle in front are positively correlated with risk, while the proportion of large vehicles in adjacent lanes is negatively correlated with risk. The two types of characteristics, namely the vehicles own motion state and the micro interaction with the vehicle in front, have a significant impact on conflict risk, while the macro traffic characteristics have a relatively small impact. References | Related Articles | Metrics

Select

Driving Style Recognition of Electric City Bus Entering Stations Based on CNN ZHAO Dengfeng1， ZHONG Yudong1，LIU Zhaohui2，LI Zhenying2，HOU Junjian1 2023, 42(12): 121-128.  DOI: 10.3969/j.issn.1674-0696.2023.12.17 Abstract ( )   PDF (1558KB) ( )   The drivers driving style of electric city bus has an important impact on the safety of urban public transport. In order to identify the driving style of the driver, a feature extraction network composed of convolutional layer and pooling layers was used to deeply fuse and automatically extract multi-channel feature data, by using the onboard CAN data in the process of the drivers natural driving electric city buses entering stations. It seamlessly output to fully connected neural networks for inbound driving style recognition, and an electric city bus driver inbound driving style recognition model was constructed. The research shows that the proposed model can effectively integrate the corresponding time series data of driving behavior and vehicle operation status during the entry process, and automatically extract higher-order features of driving behavior, achieving effective recognition of the driving style of electric city bus drivers entering the station, with an accuracy rate of 98.2%. The research results help to identify drivers with aggressive driving styles, so as to carry out targeted driving safety education and thereby reduce driver-induced electric city bus traffic accidents. References | Related Articles | Metrics

Select

Influence of Lighting Conditions on Visual Behavior of Urban Road Cyclists PAN Yiyong1, LU Yanlin1,2, WANG Xinyue1, GONG Xiaolin1 2023, 42(12): 129-136.  DOI: 10.3969/j.issn.1674-0696.2023.12.18 Abstract ( )   PDF (2023KB) ( )   To analyze the effect of lighting conditions on the visual behavior of urban road cyclists, eye movement experiments were conducted by using TobiiGlasses eye-tracking devices under three kinds of conditions: daytime, evening and nighttime. The fixation, scanning, blinking, and pupil indicators of cyclists under three kinds of conditions were compared and analyzed. K-means clustering was used and integrated with scenes to divide gaze regions, and the cyclists gaze transfer probability and stability probability were obtained by Markov chains. Indicators was established to analyze the visual change rate of cyclists. The results show that: cyclists visual field spreads gradually as light fades, and the degree of visual load is inversely proportional to light level. When external lighting weakens, the probability of gaze transfer to distant and brighter objects is higher. In both processes of light fading, cyclists perception and access to hazards decreases more significantly from day to evening, the probability of balancing various regions is slightly higher, and cyclists tension is higher from evening to night. References | Related Articles | Metrics

Transportation Equipment

Select

Sliding Mode Control for Automatic Driving of Straddle Monorail Vehicles Based on RBFNN LIU Chaotao1,LIU Haoming1,DU Zixue1, WU Haoxin2,HOU Zhongwei2 2023, 42(12): 137-142.  DOI: 10.3969/j.issn.1674-0696.2023.12.19 Abstract ( )   PDF (723KB) ( )   Aiming at the problem of full-automatic driving control of straddle monorail, based on the analysis of the operation scene of straddle monorail, the dynamic model of straddle monorail based on RBFNN was established, and the control target was clearly defined. The fixed time sliding mode control method of straddle monorail based on RBFNN was proposed, and the fixed time sliding mode controller of straddle monorail based on RBFNN was designed. The stability of the proposed controller was proved based on Lyapunov stability theory. The numerical simulation results show that the designed control algorithm can make the vehicle position and speed track the command curve in 15s, while the finite time controller can track the command curve in 24s. Compared with the controller without RBFNN, the deigned controller with RBFNN is closer to the command position about 0.1m in position tracking and 0.01 m/s in speed tracking. The simulation results show that the designed control algorithm can effectively improve the operation efficiency of straddle monorail vehicles, which can provide control algorithm reference for the implementation of straddle monorail full-automatic driving. References | Related Articles | Metrics

Select

Vehicle Adaptive Cruise Control Strategy Considering Road Slope FENG Li，ZENG Hui 2023, 42(12): 143-150.  DOI: 10.3969/j.issn.1674-0696.2023.12.20 Abstract ( )   PDF (1434KB) ( )   The adaptive cruise control (ACC) strategy based on real-time estimation of road slope was proposed to address the issue of insufficient control accuracy and safety in vehicle ACC systems under ramp driving conditions. The algorithm adopted a hierarchical control structure, dividing the ACC system into upper controller and lower controller. The upper controller employed PID controller and linear quadratic regulator (LQR) to calculate the expected acceleration, and the lower controller utilized the unscented Kalman filter (UKF) algorithm for road slope estimation. Based on the longitudinal dynamics of the vehicle, considering the impact of road slope changes, the expected acceleration was converted into the corresponding throttle opening and brake pressure to achieve vehicle cruise and following functions. The feasibility of the proposed ACC system strategy was verified through MATLAB/Simulink and Carsim co-simulation and compared with traditional control strategies. Simulation results demonstrate that compared to traditional control strategies, the improved ACC system control strategy can accurately identify road gradients and has better control accuracy and safety under ramp driving conditions. References | Related Articles | Metrics