城市轨道交通 列车故障影响仿真分析系统

研究城市轨道交通列车故障影响的分析方法,采用仿真技术描述故障车、救援车、连挂车、运营车等不同对象运动过程。以上海轨道交通为背景,梳理列车故障处置的一般作业流程,并将线路运营划分为正常、故障、救援和恢复4种状态;针对列车自动保护ATP系统切断后连挂车与运营车之间的追踪运行过程建立模型与算法;在仿真系统中,开放了对故障事件以及救援方案的信息访问和管理,支持分析不同条件下(如故障处置流程、连挂车运行组织、线路配线设计等)列车故障对线路运营的影响。建立上海轨道交通8号线列车故障影响仿真分析平台,实现对某一历史故障事件的过程模拟,并分析故障地点、连挂车运行速度和退出点对线路"故障"和"救援"阶段列车运行的影响,论证了仿真分析系统的有效性。     

城市轨道交通运营客流交通状态评价

客观评价客流交通状态对于改善城市轨道交通运营服务水平、提高运营管理效率具有重要意义。在定义城轨运营客流交通状态的基础上,以乘客流的均衡程度和顺畅程度为准则,构建了客流交通状态的三层评价指标体系;根据某城市地铁1号线运营实际客流数据,计算各评价指标,并用层次分析法对客流交通状态进行评价。评价结果与实际情况相吻合,验证了城轨运营客流交通状态评价体系的合理性,能够为城市轨道交通运营管理提供理论支持。     

监测技术在长大货车运输中的应用与发展

在超限超重货物运输中,由于货物及车辆的特殊性和对安全性的高度要求,需要对载重量很大的长大货车运输进行均载检测及全程技术监测。介绍超大型设备铁路运输监测的发展过程及其各阶段的技术特点,VXI动态数据采集系统及IMC数据采集系统的特点,展望今后监测的技术发展方向,更好地为国家重点建设用大型装备运输服务。     

确定刚架系杆拱桥合理吊杆力及成桥状态的分步算法探讨

对刚架系杆拱桥而言,合理确定成桥状态下的吊杆力是一项十分重要而繁杂的工作。结合永修刚架系杆拱桥,引用斜拉桥合理成桥状态计算中的方法,提出刚架系杆拱桥的综合应力平衡法、二次规划法、弯曲能量法的分步算法来确定其合理成桥状态。分两步来确定合理成桥状态：先确定主梁的合理受力状态;然后再根据合理成桥状态的要求确定全桥的恒载状态,该方法简单、有效。     

Regional fishery management councils and the display of scientific authority

Abstract

Natural resource management entities such as the Regional Fishery Management Councils established by the Magnuson Fishery Conservation and Management Act of 1976 depend heavily on science to inform policymakers and to legitimate the policy process. This paper discusses the importance of fishery science to the council system, contrasts the functions of Scientific and Statistical Committees (SSCs) serving the Pacific Fishery Management Council and the New England Fishery Management Council, and remarks on the implications of differences in the display of scientific authority by these SSCs.     

Non-steady state modelling of wheel-rail contact problem for the dynamic simulation of railway vehicles

Abstract

This paper deals with the solution of the non-steady state wheel-rail contact problem. Firstly, the existing models are analysed and it is concluded that none of them have the computational efficiency and/or accuracy characteristics required to be used in a railway simulation programme. Following this, a new solution is proposed to the problem that allows obtaining sufficiently accurate results with a relatively low computational cost. During the development of the proposed method it has been assumed that only one type of creepage is variable with respect to the time. Further work is necessary to extend it to more general cases.     

Nonlinear modelling of high-speed catenary based on analytical expressions of cable and truss elements

Due to the intrinsic nonlinear characteristics and complex structure of the high-speed catenary system, a modelling method is proposed based on the analytical expressions of nonlinear cable and truss elements. The calculation procedure for solving the initial equilibrium state is proposed based on the Newton–Raphson iteration method. The deformed configuration of the catenary system as well as the initial length of each wire can be calculated. Its accuracy and validity of computing the initial equilibrium state are verified by comparison with the separate model method, absolute nodal coordinate formulation and other methods in the previous literatures. Then, the proposed model is combined with a lumped pantograph model and a dynamic simulation procedure is proposed. The accuracy is guaranteed by the multiple iterative calculations in each time step. The dynamic performance of the proposed model is validated by comparison with EN 50318, the results of the finite element method software and SIEMENS simulation report, respectively. At last, the influence of the catenary design parameters (such as the reserved sag and pre-tension) on the dynamic performance is preliminarily analysed by using the proposed model.     

Lateral load transfer and normal forces estimation for vehicle safety: experimental test

Knowledge of vehicle dynamics data is important for vehicle control systems that aim to enhance vehicle handling and passenger safety. This study introduces observers that estimate lateral load transfer and wheel–ground contact normal forces, commonly known as vertical forces. The proposed method is based on the dynamic response of a vehicle instrumented with cheap and currently available standard sensors. The estimation process is separated into three blocks: the first block serves to identify the vehicle’s mass, the second block contains a linear observer whose main role is to estimate the roll angle and the one-side lateral transfer load, while in the third block we compare linear and nonlinear models for the estimation of four wheel vertical forces. The different observers are based on a prediction/estimation filter. The performance of this concept is tested and compared with real experimental data acquired using the INRETS-MA (Institut National de Recherche sur les Transports et leur Sécurité – Département Mécanismes d’Accidents) Laboratory car. Experimental results demonstrate the ability of this approach to provide accurate estimation, thus showing its potential as a practical low-cost solution for calculating normal forces.     

Using the lead vehicle as preview sensor in convoy vehicle active suspension control

Both ride quality and roadholding of actively suspended vehicles can be improved by sensing the road ahead of the vehicle and using this information in a preview controller. Previous applications have used look-ahead sensors mounted on the front bumper to measure terrain beneath. Such sensors are vulnerable, potentially confused by water, snow, or other soft obstacles and offer a fixed preview time. For convoy vehicle applications, this paper proposes using the overall response of the preceding vehicle(s) to generate preview controller information for follower vehicles. A robust observer is used to estimate the states of a quarter-car vehicle model, from which road profile is estimated and passed on to the follower vehicle(s) to generate a preview function. The preview-active suspension, implemented in discrete time using a shift register approach to improve simulation time, reduces sprung mass acceleration and dynamic tyre deflection peaks by more than 50% and 40%, respectively. Terrain can change from one vehicle to the next if a loose obstacle is dislodged, or if the vehicle paths are sufficiently different so that one vehicle misses a discrete road event. The resulting spurious preview information can give suspension performance worse than that of a passive or conventional active system. In this paper, each vehicle can effectively estimate the road profile based on its own state trajectory. By comparing its own road estimate with the preview information, preview errors can be detected and suspension control quickly switched from preview to conventional active control to preserve performance improvements compared to passive suspensions.     

道岔区轮轨力转移与分配特性研究

道岔区复杂的轮轨接触状态决定了其轮轨力特性与一般线路相比存在较大的差异。利用空间轮轨接触几何关系理论和Hertz非线性弹性接触理论，研究道岔区车轮与同侧并列的2股钢轨同时接触的2点接触问题。依据2点接触时轮轨弹性压缩量计算每一接触点上的轮轨力，由此确定车辆侧向和直向通过时的轮轨2点接触范围以及轮轨力转移和分配特性。结果表明：2股钢轨上轮轨力转移和分配特性不仅与钢轨外形、轨顶高度和宽度有关，而且与车辆过岔方式有关；考虑轮轨2点接触后的计算方法，消除了单点接触轮轨力计算中轮轨接触点从一股钢轨转移到另一股钢轨上时引起的轮轨力突变，使得轮轨力变化更为平顺和真实。