Modelling,simulation and applications of longitudinal train dynamics

ABSTRACT

Significant developments in longitudinal train simulation and an overview of the approaches to train models and modelling vehicle force inputs are firstly presented. The most important modelling task, that of the wagon connection, consisting of energy absorption devices such as draft gears and buffers, draw gear stiffness, coupler slack and structural stiffness is then presented. Detailed attention is given to the modelling approaches for friction wedge damped and polymer draft gears. A significant issue in longitudinal train dynamics is the modelling and calculation of the input forces – the co-dimensional problem. The need to push traction performances higher has led to research and improvement in the accuracy of traction modelling which is discussed. A co-simulation method that combines longitudinal train simulation, locomotive traction control and locomotive vehicle dynamics is presented. The modelling of other forces, braking propulsion resistance, curve drag and grade forces are also discussed. As extensions to conventional longitudinal train dynamics, lateral forces and coupler impacts are examined in regards to interaction with wagon lateral and vertical dynamics. Various applications of longitudinal train dynamics are then presented. As an alternative to the tradition single wagon mass approach to longitudinal train dynamics, an example incorporating fully detailed wagon dynamics is presented for a crash analysis problem. Further applications of starting traction, air braking, distributed power, energy analysis and tippler operation are also presented.     

Identity-based broadcast encryption with shorter transmissions

This paper describes two identity-based broadcast encryption(IBBE) schemes for mobile ad hoc networks.The first scheme proposed achieves sub-linear size cipertexts and the second scheme achieves O(1)-size ciphertexts.Furthermore, when the public keys are transmitted, the two schemes have short transmissions and achieve O(1) user storage cost, which are important for a mobile ad hoc network.Finally, the proposed schemes are provable security under the decision generalized bilinear Di?-Hellman(GBDH) assumption in the random oracles model.     

计算机数据安全隐患及防护措施

从分析计算机数据的物理安全和逻辑安全两个方面入手,对电磁波辐射、联网及病毒对计算机数据安全的威胁进行了论述,指出这是威胁计算机数据安全的主要因素,并提出了数据备份、数据安全删除、辐射屏蔽、病毒及入侵防护、文档加密等相应的安全防护措施和方法。     

基于PLC的船舶安全报警系统设计

为保证船舶安全航行,船舶一般都配备有安全报警系统。随着计算机技术、网络技术和控制技术的发展,船舶报警系统向着信息化、网络化和智能化的方向发展。本文结合当前船舶安全报警系统的实际应用需求,以PLC为核心控制器设计了一套完整的船舶安全报警系统。本文首先对系统硬件和软件的结构和功能进行简单介绍,然后针对基于PLC的机船安全报警系统各模块的硬件组态、网络组态和控制程序进行了详细的设计,最后完成了安全报警系统人机交互界面的设计。     

Enhancing stated preference surveys in transportation research: the contribution of geographic information systems

In this paper we argue that visualization, data management and computational capabilities of geographic information systems (GIS) can assist transportation stated preference research in capturing the contextual complexity of many transportation decision environments by providing respondents with maps and other spatial and non-spatial information in graphical form that enhance respondents' understanding of decision scenarios. We explore the multiple inherent contributions of GIS to transportation stated preference data collection and propose a framework for a GIS-based stated preference survey instrument. We also present the design concepts of two survey prototypes and their GIS implementation for a sample travel mode choice problem.     

核安全级柴油发电机组的抗震试验

通过抗震试验,测定安全级设备的自振频率、振型、阻尼等振动参数和地震反应,考核设备的刚度(变形)、强度和位移,验证设备在地震载荷的作用下能否正常工作,保持其完整性和可运行性,以履行其安全功能。     

汽车线控转向系统的初步研究

线控转向是汽车未来转向技术的发展方向。简单介绍了汽车线控转向系统的结构和工作原理：重点分析汽车线控转向系统的安全性，阐述线控转向系统的失效原因及失效模式，提出一种安全结构，并对该结构硬件和软件设置进行分析；最后指出当前发展汽车线控转向系统的关键技术。     

校园网安全问题及策略

本文详细分析了现有校园网存在的安全问题,结合目前广泛应用的网络安全技术,构建了一个全面的校园网安全解决方案,然后对这个安全解决方案进行了论述.     

浅埋偏压桥隧相接隧道出洞施工技术

受隧道洞口地质、地形条件的限制,山岭隧道选择出洞施工的情况逐渐增多,相应的技术要求也越来越高。安康至岚皋高速公路长春隧道出口端位于浅埋偏压山体以及桥隧相接处,且一侧下方紧邻S207省道,故在选择出洞施工时,通过修筑挡墙、搭设防护棚和实施交通管制等措施确保S207省道行车安全,采用小导洞出洞,经由它将机械、人员送出洞外,进行边仰坡开挖及防护施工;洞外管棚施作完成后,由内向外采取环形预留核心土法贯通,保障了隧道出洞施工的安全。     

A critical review of container security operations

Containers, which permit fast and safe handling between modal systems, are the main equipment used in intermodal transport. Unfortunately, enhancement of the efficiency and velocity of container operations has created a breach in traditional security, also known as container security. This paper presents a critical literature review of container security operations. We aim to identify current trends and future research directions in container security. We propose a classification framework based on the following elements: presenting the container security perspective, identifying threats, evaluating container security, balancing costs/benefits and the degree of security, balancing time savings/reduction and the degree of security, and securing containerized transportation processes. We discuss the current studies of these problems, the methodologies adopted and important insights into container security.