With the rapid development of urban rail transit,there have been an urgent problem of excessive stray current.Because the stray current distribution is random and difficult to verify in the field,we designed an improv...With the rapid development of urban rail transit,there have been an urgent problem of excessive stray current.Because the stray current distribution is random and difficult to verify in the field,we designed an improved stray current experimental platform by replacing the simulated aqueous solution with a real soil environment and by calculating the transition resistance by measuring the soil resistivity,which makes up for the defects in the previous references.Firstly,the mathematical models of rail-drainage net and rail-drainage netground were established,and the analytical expressions of current and voltage of rail,drainage net and other structures were derived.In addition,the simulation model was built,and the mathematical analysis results were compared with the simulation results.Secondly,the accuracy of the improved stray current experimental platform was verified by comparing the measured and simulation results.Finally,based on the experimental results,the influence factors of stray current were analyzed.The relevant conclusions provide experimental data and theoretical reference for the study of stray current in urban rail transit.展开更多
In order to obtain the trend of urban rail transit traffic flow and grasp the fluctuation range of passenger flow better,this paper proposes a combined forecasting model of passenger flow fluctuation range based on fu...In order to obtain the trend of urban rail transit traffic flow and grasp the fluctuation range of passenger flow better,this paper proposes a combined forecasting model of passenger flow fluctuation range based on fuzzy information granulation and least squares support vector machine(LS-SVM)optimized by chaos particle swarm optimization(CPSO).Due to the nonlinearity and fluctuation of the passenger flow,firstly,fuzzy information granulation is used to extract the valid data from the window according to the requirement.Secondly,CPSO that has strong global search ability is applied to optimize the parameters of the LS-SVM forecasting model.Finally,the combined model is used to forecast the fluctuation range of early peak passenger flow at Tiyu Xilu Station of Guangzhou Metro Line 3 in 2014,and the results are compared and analyzed with other models.Simulation results demonstrate that the combined forecasting model can effectively track the fluctuation of passenger flow,which provides an effective method for predicting the fluctuation range of short-term passenger flow in the future.展开更多
In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network ...In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network method first.After measuring the soil resistivity of a real subway system,a simulation model is established in Matlab to obtain the stray currents at different soil resistivities.Then the influence of soil resistivity on stray current is analyzed.Afterwards,to verify the rationality and reliability of the simulation model,we design a test circuit to measure the stray current and rail-to-ground voltage in a real subway system,and a comparison of the experimentally measured results and simulation results is presented.The results show that the stray current is the maximum when the soil resistivity is 211.57Ω·m;when the soil resistivity is 768.47Ω·m,the stray current is the minimum,that is,the smaller the soil resistivity,the greater the stray current.Therefore,the resistivity should be increased as much as possible when ramming the track foundation in urban rail transit system.展开更多
In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different sc...In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different schemes for trains passing through station are considered. One is the scheme of ＂pass by the main track, start and stop by the siding track＂. The other is the scheme of ＂two tracks play the same role＂. We simulate the train movement using the proposed model and analyze the traffic flow at station. The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic. Some characteristic behaviors of railway traffic flow can be reproduced. Moreover, the simulation values of the minimum headway are close to the theoretical values. This result demonstrates the dependability and availability of the proposed model.展开更多
基金supported by National Natural Science Foundation of China(Nos.51476073,51266004)Natural Science Foundation of Gansu Province(No.138RJZA199).
文摘With the rapid development of urban rail transit,there have been an urgent problem of excessive stray current.Because the stray current distribution is random and difficult to verify in the field,we designed an improved stray current experimental platform by replacing the simulated aqueous solution with a real soil environment and by calculating the transition resistance by measuring the soil resistivity,which makes up for the defects in the previous references.Firstly,the mathematical models of rail-drainage net and rail-drainage netground were established,and the analytical expressions of current and voltage of rail,drainage net and other structures were derived.In addition,the simulation model was built,and the mathematical analysis results were compared with the simulation results.Secondly,the accuracy of the improved stray current experimental platform was verified by comparing the measured and simulation results.Finally,based on the experimental results,the influence factors of stray current were analyzed.The relevant conclusions provide experimental data and theoretical reference for the study of stray current in urban rail transit.
基金National Natural Science Foundation of China(No.61663021)Science and Technology Support Project of Gansu Province(No.1304GKCA023)Scientific Research Project in University of Gansu Province(No.2017A-025)
文摘In order to obtain the trend of urban rail transit traffic flow and grasp the fluctuation range of passenger flow better,this paper proposes a combined forecasting model of passenger flow fluctuation range based on fuzzy information granulation and least squares support vector machine(LS-SVM)optimized by chaos particle swarm optimization(CPSO).Due to the nonlinearity and fluctuation of the passenger flow,firstly,fuzzy information granulation is used to extract the valid data from the window according to the requirement.Secondly,CPSO that has strong global search ability is applied to optimize the parameters of the LS-SVM forecasting model.Finally,the combined model is used to forecast the fluctuation range of early peak passenger flow at Tiyu Xilu Station of Guangzhou Metro Line 3 in 2014,and the results are compared and analyzed with other models.Simulation results demonstrate that the combined forecasting model can effectively track the fluctuation of passenger flow,which provides an effective method for predicting the fluctuation range of short-term passenger flow in the future.
基金National Natural Science Foundation of China(Nos.51476073,51266004)Natural Science Foundation of Gansu Province(No.1308RJZA199)。
文摘In order to explore the influence of soil resistivity on stray current in power supply system of urban rail transit,we establish an equivalent circuit model of the rail-to-ground structure based on resistance network method first.After measuring the soil resistivity of a real subway system,a simulation model is established in Matlab to obtain the stray currents at different soil resistivities.Then the influence of soil resistivity on stray current is analyzed.Afterwards,to verify the rationality and reliability of the simulation model,we design a test circuit to measure the stray current and rail-to-ground voltage in a real subway system,and a comparison of the experimentally measured results and simulation results is presented.The results show that the stray current is the maximum when the soil resistivity is 211.57Ω·m;when the soil resistivity is 768.47Ω·m,the stray current is the minimum,that is,the smaller the soil resistivity,the greater the stray current.Therefore,the resistivity should be increased as much as possible when ramming the track foundation in urban rail transit system.
基金supported by National Natural Science Foundation of China under Grant Nos. 60634010 and 60776829Key Technology Research of Train Control System,and Urban Rail Transit Automation and Control Beijing Municipal Government Key Laboratory
文摘In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different schemes for trains passing through station are considered. One is the scheme of ＂pass by the main track, start and stop by the siding track＂. The other is the scheme of ＂two tracks play the same role＂. We simulate the train movement using the proposed model and analyze the traffic flow at station. The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic. Some characteristic behaviors of railway traffic flow can be reproduced. Moreover, the simulation values of the minimum headway are close to the theoretical values. This result demonstrates the dependability and availability of the proposed model.
