Tamping squeeze is essential for maintaining ballasted tracks.Previous studies have simulated squeezing behavior as a linear motion with a constant squeezing distance,which is unsuitable for various ballast beds in th...Tamping squeeze is essential for maintaining ballasted tracks.Previous studies have simulated squeezing behavior as a linear motion with a constant squeezing distance,which is unsuitable for various ballast beds in the field.This study aims to develop realistic formulas for squeezing behavior in tamping maintenance.First,a universal expression for the squeezing behavior of tamping operation was proposed through theoretical derivation.Subsequently,a custom testing method for squeezing distance with high accuracy was designed.Finally,the parameters of the universal expression were obtained from testing results using the response surface method and novel formulas for squeezing behavior were innovatively developed.This study can lead to greatly improved simulation accuracy and effective maintenance of tamping squeeze.展开更多
数字化控制是核电发展的必然趋势,核电厂数字化控制系统(Digital Control System,DCS)的应用在提高核电厂系统控制能力的同时也增加了系统的复杂性,以事件链模型为基础的传统安全分析技术面临挑战。为提高核电厂DCS的安全性能,需要关注...数字化控制是核电发展的必然趋势,核电厂数字化控制系统(Digital Control System,DCS)的应用在提高核电厂系统控制能力的同时也增加了系统的复杂性,以事件链模型为基础的传统安全分析技术面临挑战。为提高核电厂DCS的安全性能,需要关注安全工程领域的新研究成果,将其引入到核电安全领域并加以研究。本文介绍一种新的基于系统理论的事故模型和过程(Systems-Theoretic Accident Modeling and Processes,STAMP)安全模型,对比分析了其与传统安全模型的优缺点,说明了基于STAMP的风险分析(STAMP-Based HazardAnalysis,STPA)技术的基本步骤,并根据STAMP在国内外的应用情况,对STAMP在我国核电领域的发展前景进行了展望。展开更多
Heavy tamping is one of the important methods for ground treatment. But the vibration is often a problem that restricts the application during heavy tamping. On the other hand, as an instant impact load with controlla...Heavy tamping is one of the important methods for ground treatment. But the vibration is often a problem that restricts the application during heavy tamping. On the other hand, as an instant impact load with controllable energy, heavy tamping is a good test in situ for the study of soil dynamics. With the analysis in the field of frequency, deductive method for medium effecting function and excitation function of heavy tamping is put forward in this paper.展开更多
A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibrati...A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibration.A new spin valve was designed in order to fulfill dynamic state requirements of the oscillation cylinder.Parametric analysis was carried out by establishing mathematic model.Then,the relationships among the structure of valve port and the frequency,amplitude,output shock force of the cylinder were researched.An experimental device of the electrohydraulic exciter was established to validate the theoretical results.The signals were acquired by AVANT dynamic signal analyser of vibration.The results show that new tamping device can satisfy all kinds of complex working conditions with the flexible adjustment of frequency and amplitude.展开更多
In the novel approach to the diagnostic tests of continuous welded rail （CWR） track by the use of the tamping machine, the fundamental statement related to the recording of the curvature with a definite value of the...In the novel approach to the diagnostic tests of continuous welded rail （CWR） track by the use of the tamping machine, the fundamental statement related to the recording of the curvature with a definite value of the lateral displacement being subjected to verification, can provide a basis for the determination of the longitudinal axial force in the rail. An attempt has also been made to define an alternative factor which by means of the measured signals, could be used for the determination of the axial forces in the rail sections. A power engineering approach has been adopted to this concept. Within the framework of the experimental investigations, measurements were carried out in the track test section. The investigations were based on stretching the rail sections by stretchers and on lateral displacements of the track by the tamping machine. The operation of the measuring apparatus was also tested in the experimental railway track section while carrying out the geometrical adjustments by the tamping machine. As a result of next series of the investigation carried out in 2006-2007, the authors worked out a procedure of estimating the longitudinal forces in rails of CWR track.展开更多
The fundamental solution to dynamic elastic differential equation after the Laplace transformation, which was obtained by Cruse and Rizzo, has been utilized to solve the boundary integral equation formulated by the we...The fundamental solution to dynamic elastic differential equation after the Laplace transformation, which was obtained by Cruse and Rizzo, has been utilized to solve the boundary integral equation formulated by the weighted residual method. The boundary element method has been applied to dealing with the heavy tamping problem. As the elasticity modulus of soil is gradually increased after each tamping, and the loading modulus and unloading modulus are quite different, residual deformations can be finally obtained for each tamping. This is a method of nonlinear elastic analysis. The relationship of hammer velocity and falling distance for heavy tamping within liquid has been derived, so providing a theoretical background for heavy tamping under water.展开更多
基金supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation under Grant Number GZC20240099the Fundamental Research Funds for the Central Universities under Grant Number 2024XKRC034 and 2022JBQY009。
文摘Tamping squeeze is essential for maintaining ballasted tracks.Previous studies have simulated squeezing behavior as a linear motion with a constant squeezing distance,which is unsuitable for various ballast beds in the field.This study aims to develop realistic formulas for squeezing behavior in tamping maintenance.First,a universal expression for the squeezing behavior of tamping operation was proposed through theoretical derivation.Subsequently,a custom testing method for squeezing distance with high accuracy was designed.Finally,the parameters of the universal expression were obtained from testing results using the response surface method and novel formulas for squeezing behavior were innovatively developed.This study can lead to greatly improved simulation accuracy and effective maintenance of tamping squeeze.
文摘数字化控制是核电发展的必然趋势,核电厂数字化控制系统(Digital Control System,DCS)的应用在提高核电厂系统控制能力的同时也增加了系统的复杂性,以事件链模型为基础的传统安全分析技术面临挑战。为提高核电厂DCS的安全性能,需要关注安全工程领域的新研究成果,将其引入到核电安全领域并加以研究。本文介绍一种新的基于系统理论的事故模型和过程(Systems-Theoretic Accident Modeling and Processes,STAMP)安全模型,对比分析了其与传统安全模型的优缺点,说明了基于STAMP的风险分析(STAMP-Based HazardAnalysis,STPA)技术的基本步骤,并根据STAMP在国内外的应用情况,对STAMP在我国核电领域的发展前景进行了展望。
文摘Heavy tamping is one of the important methods for ground treatment. But the vibration is often a problem that restricts the application during heavy tamping. On the other hand, as an instant impact load with controllable energy, heavy tamping is a good test in situ for the study of soil dynamics. With the analysis in the field of frequency, deductive method for medium effecting function and excitation function of heavy tamping is put forward in this paper.
基金Projects(50975252,51275499)supported by the National Natural Science Foundation of ChinaProject(2013CB035404)supported by the National Basic Research Program of ChinaProject(GZKF-201312)supported by Open Foundation of the State Key Laboratory of Fluid Power Transmission and Control,China
文摘A new tamping device which is driven by an electrohydraulic exciter was proposed to overcome the limitations of mechanically driven devices.The double-rod oscillation cylinder drives the tamping arm to realize vibration.A new spin valve was designed in order to fulfill dynamic state requirements of the oscillation cylinder.Parametric analysis was carried out by establishing mathematic model.Then,the relationships among the structure of valve port and the frequency,amplitude,output shock force of the cylinder were researched.An experimental device of the electrohydraulic exciter was established to validate the theoretical results.The signals were acquired by AVANT dynamic signal analyser of vibration.The results show that new tamping device can satisfy all kinds of complex working conditions with the flexible adjustment of frequency and amplitude.
文摘In the novel approach to the diagnostic tests of continuous welded rail （CWR） track by the use of the tamping machine, the fundamental statement related to the recording of the curvature with a definite value of the lateral displacement being subjected to verification, can provide a basis for the determination of the longitudinal axial force in the rail. An attempt has also been made to define an alternative factor which by means of the measured signals, could be used for the determination of the axial forces in the rail sections. A power engineering approach has been adopted to this concept. Within the framework of the experimental investigations, measurements were carried out in the track test section. The investigations were based on stretching the rail sections by stretchers and on lateral displacements of the track by the tamping machine. The operation of the measuring apparatus was also tested in the experimental railway track section while carrying out the geometrical adjustments by the tamping machine. As a result of next series of the investigation carried out in 2006-2007, the authors worked out a procedure of estimating the longitudinal forces in rails of CWR track.
文摘The fundamental solution to dynamic elastic differential equation after the Laplace transformation, which was obtained by Cruse and Rizzo, has been utilized to solve the boundary integral equation formulated by the weighted residual method. The boundary element method has been applied to dealing with the heavy tamping problem. As the elasticity modulus of soil is gradually increased after each tamping, and the loading modulus and unloading modulus are quite different, residual deformations can be finally obtained for each tamping. This is a method of nonlinear elastic analysis. The relationship of hammer velocity and falling distance for heavy tamping within liquid has been derived, so providing a theoretical background for heavy tamping under water.
