Train positioning is the key to ensure the transportation and efficient operation of the railway.Due to the low accuracy and the poor real-time of the train positioning,a train positioning system based on global navig...Train positioning is the key to ensure the transportation and efficient operation of the railway.Due to the low accuracy and the poor real-time of the train positioning,a train positioning system based on global navigation satellite system/inertial measurement unit/odometer(GNSS/IMU/ODO)combination framework and a train integrated positioning method based on grey neural network are put forward.A data updating method based on the established grey prediction model of train positioning is put forward,which uses the accumulation and summary of the grey theory for the rough prediction of the data.The purpose of the method is to reduce the noise of the original data.Moreover,the radial basis function(RBF)neural network is introduced to correct residual sequence of the grey prediction model.Compared with the single model calibration,this method can make full use of the advantages of each model,thus getting a high positioning accuracy in the case of small samples and poor information.Experiments show that the method has good real-time performance and high accuracy,and has certain application value.展开更多
The railway transport is one of the main types of communications in the world. Analysis of service conditions of the most critical elements of the railway transport rolling stock （mils, wheels and tyres） shows that ...The railway transport is one of the main types of communications in the world. Analysis of service conditions of the most critical elements of the railway transport rolling stock （mils, wheels and tyres） shows that one of the main factors determining their reliability and service life is the structural-phase state of steel, which is formed in the process of its producing. Complication of service conditions leads to the more severe requirements, specified by the consumers, where the high level of strength and hardness should be combined with high values of ductility and toughness. Realization of these requirements is possible only at the integrated approach to the improvement of technology of their production on the basis of profound knowledge in kinetics of austenite decay processes of structure formation and its contribution to the mechanical properties. With the formation of mainly bainite-martensite structures in the HAZ （heat-affected zone） metal of welded joints of these steels and saturation of this region with diffusive hydrogen their susceptibility to the cold cracking is increased. In this connection this work presents the results of investigations of effect of the WTC （welding thermal cycles） on the nature of structural transformations, hardness, static strength and resistance to the formation of cold cracks in HAZ metal of high-strength carbon rail steel M76. For this purpose, the structure and kinetics of transformation of an overcooled austenite was studied using the advanced methods of physical materials science by the modeling of phase transformations in the Gleeble 3800 unit. It was found that the cause of reduction in mechanical properties of welded joints of steel M76 is the formation of regions with a completely martensite structure in the amount of up to 5%. Results of investigations will be applied for the optimizing the technology and conditions of FBW of the advanced rail steels. 10 Ref., 4 Tables, 11 Figures.展开更多
基金Gansu Province Basic Research Innovation Group Plan(No.1606RJIA327)Natural Science Foundation of Gansu Province(No.1606RJYA225)+1 种基金Lanzhou Jiaotong University Youth Fund(No.2014031)Longyuan Youth Innovative Support Program(No.2016-43)
文摘Train positioning is the key to ensure the transportation and efficient operation of the railway.Due to the low accuracy and the poor real-time of the train positioning,a train positioning system based on global navigation satellite system/inertial measurement unit/odometer(GNSS/IMU/ODO)combination framework and a train integrated positioning method based on grey neural network are put forward.A data updating method based on the established grey prediction model of train positioning is put forward,which uses the accumulation and summary of the grey theory for the rough prediction of the data.The purpose of the method is to reduce the noise of the original data.Moreover,the radial basis function(RBF)neural network is introduced to correct residual sequence of the grey prediction model.Compared with the single model calibration,this method can make full use of the advantages of each model,thus getting a high positioning accuracy in the case of small samples and poor information.Experiments show that the method has good real-time performance and high accuracy,and has certain application value.
文摘The railway transport is one of the main types of communications in the world. Analysis of service conditions of the most critical elements of the railway transport rolling stock （mils, wheels and tyres） shows that one of the main factors determining their reliability and service life is the structural-phase state of steel, which is formed in the process of its producing. Complication of service conditions leads to the more severe requirements, specified by the consumers, where the high level of strength and hardness should be combined with high values of ductility and toughness. Realization of these requirements is possible only at the integrated approach to the improvement of technology of their production on the basis of profound knowledge in kinetics of austenite decay processes of structure formation and its contribution to the mechanical properties. With the formation of mainly bainite-martensite structures in the HAZ （heat-affected zone） metal of welded joints of these steels and saturation of this region with diffusive hydrogen their susceptibility to the cold cracking is increased. In this connection this work presents the results of investigations of effect of the WTC （welding thermal cycles） on the nature of structural transformations, hardness, static strength and resistance to the formation of cold cracks in HAZ metal of high-strength carbon rail steel M76. For this purpose, the structure and kinetics of transformation of an overcooled austenite was studied using the advanced methods of physical materials science by the modeling of phase transformations in the Gleeble 3800 unit. It was found that the cause of reduction in mechanical properties of welded joints of steel M76 is the formation of regions with a completely martensite structure in the amount of up to 5%. Results of investigations will be applied for the optimizing the technology and conditions of FBW of the advanced rail steels. 10 Ref., 4 Tables, 11 Figures.
