A health management algorithm for composite train carbody based on FEM/FBG hybrid method

In this study, a health management program for a composite train carbody was developed using the acquired strain distributions from fiber Bragg grating (FBG) sensor arrays. To determine appropriate locations for the FBG sensors, a finite element analysis (FEA) was executed. In this FEA, a FE model of the Korean tilting train (TTX) was used as a representative composite carbody train. The FEA results of various derailment situations and high speed operation on curved track were used as the database of each deformation case. In the last step, the health management program was produced using LabVIEW software. In this post-processing algorithm, the method of least squares was used to determine the difference between the FEA results and the acquired strains. This program shows the estimated deformations and plots of the acquired strains, as well as displaying an emergency indicator when necessary, all through post-processing of the strains. Finally, this FEM/FBG hybrid method was verified by several simulations using the reproductive sensor data.     

The influence of train properties on railway ground vibrations

This paper uses a sensitivity analysis to quantify the dominant train properties (mass and spacing of wheels and bogies) that contribute to ground-borne vibration generation, with the aim of reducing the complexity of train–track numerical models. This research is significant because ground-borne vibration from railways is a growing problem, particularly in urban areas. Despite this fact, attempting to predict vibration levels is complex because there are many variables that contribute to the overall dynamic response. Therefore, a deterministic approach is commonly used, that ignores many of these variables. Thus, this paper identifies the variables that can be ignored, while highlighting those that are highly influential on vibration generation. For this purpose, a previously validated 2.5D finite elements-boundary elements approach is used to simulate dynamic train–track interaction. It is computed many times for a variety of modelling variables to investigate the effect of each on the ground-borne vibration levels in the far field. It is found that increases in unsprung mass of the train causes a large increase in vibration levels. Furthermore, changes in wheel/bogie spacing and semi-sprung mass are found to have a minimal effect on vibration generation.     

机载光测设备过顶跟踪方法

在分析了地平式跟踪架、双轴式跟踪架优缺点基础上,本文论述了一种基于机载光测设备的过顶跟踪技术,它结合了地平式跟踪架、双轴式跟踪架的优点,能够对过顶盲区的目标进行有效的跟踪。外场试验表明,该跟踪方法简单,跟踪精度3′,满足技术指标要求。     

基于扫描激光雷达的列车速度测量系统

针对传统列车速度测量装置存在量程小、调试复杂等问题,基于扫描激光雷达技术,设计了一套适用于高速列车动态限界测量的列车速度测量系统。将扫描激光雷达固定在距列车10m 左右的位置上,根据激光脉冲飞行时间测距原理,沿列车行驶方向对进入扫描范围内的列车车身逐点扫描,获得由测量点组成的车身轮廓信息;通过最小二乘拟合车厢测量点,得到列车行驶轨迹,确定列车行驶方向;采用分段线性差值确定相邻两次测量周期内列车行驶的距离,完成列车速度的测量。结果表明:该测速系统操作方便,量程可达600km/h,测速误差控制在1.2%以内,可以满足高速列车速度测量需求。     

一种应用于列车信息画面实时重建的快速绘图方法

在许多视频应用中,画面重建是一个重要的课题。提出一种应用于列车信息实时分析重建系统的快速绘图方法使用双缓存技术在内存空间申请指定大小的位图,通过图形设备接口在该位图上进行图形绘制。绘图模块对基本绘图单元进行封装,各绘图元素单元具有相似的设置接口。采用了双缓冲技术避免闪烁,同时采用部分绘制方法,提高绘制速度。该绘图模块具有很好的可扩展性、实时性和灵活性。所提出的快速绘图方法在列车信息实时分析重建系统中得到很好的应用。     

Transformations for early reply and forward message passing mechanisms

Message passing notations (language, package, etc.) typically include some form of asynchronous or synchronous invocation. In a synchronous invocation, the invoker waits for the invocation's servicer to pass back results. Some message passing notations also include early reply or deferred reply (including forwarding), which alters how and when the servicer passes back its results; this additional flexibility is useful in realistic applications. It is well known how to transform a synchronous invocation into only asynchronous invocations. This paper extends such transformations to early reply and forward. This paper also describes the use of these transformations within the implementations of programming notations. Using the transformation simplifies the implementation without significantly affecting run‐time costs. Copyright © 2015 John Wiley & Sons, Ltd.     

32m双线简支箱梁在对开列车作用下梁体竖向动力响应规律研究

将列车、双线简支箱梁分别简化为二系悬挂多刚体体系和模态函数,推导车桥系统动力方程,建立并验证车桥相互作用模型,对双线简支箱梁在对开列车作用下梁体竖向动力响应规律进行研究。研究表明:对开列车作用下,桥梁动力响应与列车运行速度及入桥距离差密切相关;列车以共同速度对开时,可引起的梁体最大挠度动力系数与单线行车作用下基本一致,但梁体动力响应值约为单线行车引起的梁体动力响应值的2倍。     

基于最大相关峭度反褶积法的行星齿轮故障诊断

针对行星轮系结构复杂,故障信号特征提取困难,提出使用扭振信号对行星齿轮箱故障进行诊断。通过对行星齿轮箱横向振动信号与扭振信号的频谱分析发现,扭振信号相对于往复振动信号更适合行星轮系的故障诊断。针对扭振信号微弱,冲击特性不明显,提出基于最大相关峭度反褶积处理扭振信号。首先对采集的行星齿轮扭振信号先进行零均值化预处理,然后使用MCKD方法增强扭振信号的冲击特性。以故障冲击特性的峭度值作为选择FIR滤波器长度的选择依据,最终使得行星齿轮箱扭振信号的故障冲击特征得到显著提升。该方法对于扭振信号的降噪与提高周期故障冲击特征有效,适用于行星齿轮箱扭振信号的故障诊断。     

高速列车框架焊接的双椭圆柱高斯分布热源模型

根据高速列车车体结构焊接工艺特点,分析并改进常用高斯热源,提出适用于铝合金惰性气体保护焊接（MIG）的双椭圆柱-高斯分布热源模型.该热源模型基于焊接速度移动,形成的熔池表面为双椭圆形状,热流密度沿厚度方向均匀分布,在径向呈高斯-双椭圆分布.基于热源模型的数学表达,以有限元方法实现了热机耦合的焊接过程仿真,与薄板试验结果比较,温度场分布与降低趋势较好地吻合;拉应力峰值出现在熔合线和热影响区,仿真值、试验值分别为88.8,85 MPa.结果表明,该热源模型有效地模拟焊接温度场时域上的变化过程,准确地预测结构变形、残余应力分布规律,应用于高速列车头车框架结构焊接工艺优化及残余应力评估,为高速列车焊接质量控制及焊接工艺参数选择提供理论指导.     

煤炭铁路动力换代后站场改造关键技术的探讨

进入 2 1世纪 ,铁路运输中机车动力换代步伐逐渐加快 ,尤其是煤炭铁路运输 ,蒸汽机车几乎被内燃机车和电力机车取代 ,随之列车牵引重量、长度、速度都相应的大幅度提高 ,原站场技术设备已不能满足运输需求 ,急需进行技术改造 ,针对站场改造过程中应注意的几点关键技术问题进一步研究和探讨。