移动荷载作用下轨道路基动力响应分析

基于层状梁和粘弹性半空间体理论建立轨道路基耦合动力分析模型;通过移动坐标和Fourier变换得到移动谐振点荷载作用下轨道路基稳态响应在波数域内的解;再利用快速Fourier逆变换,求出钢轨、轨枕位移及道碴路基的相互作用力在空间域内解。通过算例分析荷载速度对路基表面位移的影响,结果表明:随荷载速度增大,路基表面位移峰值也增大,在荷载速度较低范围内,其对路基位移峰值影响不大,当荷载速度接近Rayleigh波速时,路基位移峰值急剧增大;随着荷载速度的增大,路基竖向位移分布呈现出的“波动性”也越来越明显,其“波长”随荷载速度的增大而减小。     

城市轨道交通中移动闭塞信号系统的运用分析

本文主要对城市轨道交通中采用的两种闭塞方式的信号系统技术特点、系统能力及经济性等进行充分的分析比较,其目的是对运量较大的城市轨道交通项目信号系统方案的选择提供决策支持。     

蠕动爬行攻泥机构转向工作特性的有限元分析

针对用于沉船打捞的水下攻泥机器人蠕动爬行攻泥机构的结构与工作机理，建立了适当的有限元计算模型，进而通过弹塑性有限元计算，模拟了攻泥机构处于土中不同深度的工作情况，建立了攻泥机构前进位移V和转向角θ之间关系的通用公式。通过它可以实现对攻泥机构前进路线的规划与自动控制。     

Exact and grid-free solutions to the Lighthill–Whitham–Richards traffic flow model with bounded acceleration for a class of fundamental diagrams

In this article, we propose a new exact and grid-free numerical scheme for computing solutions associated with an hybrid traffic flow model based on the Lighthill–Whitham–Richards (LWR) partial differential equation, for a class of fundamental diagrams. In this hybrid flow model, the vehicles satisfy the LWR equation whenever possible, and have a constant acceleration otherwise. We first propose a mathematical definition of the solution as a minimization problem. We use this formulation to build a grid-free solution method for this model based on the minimization of component function. We then derive these component functions analytically for triangular fundamental diagrams, which are commonly used to model traffic flow. We also show that the proposed computational method can handle fixed or moving bottlenecks. A toolbox implementation of the resulting algorithm is briefly discussed, and posted at https://dl.dropbox.com/u/1318701/Toolbox.zip.     

适用于近地表岩土结构及不良地质体检测评价的工程VSP方法

工程VSP方法除具备现行PS测井的全部效能外,利用透射直达波和反射波信息及其内在联系,能够精细描述近地表工程探孔旁侧隐蔽构造现象的细节特征和地层关系,特别是将其用于探孔或洞室掘进工程前方岩土层弹性参数估算或不良地质体超前预测方面具有良好前景。因此,对于近地表工程地质勘探与岩土工程稳定性评价目标,工程VSP方法是值得推广应用的一种高分辨工程物探手段。文章第一部分简述了工程VSP方法的优势潜力与主要技术难点,第二部分介绍了野外资料采集方法,第三部分为近地表工程地质勘测与岩土工程应用实例资料简介。     

面向虚拟编组的列控技术研究

虚拟编组(Virtual Coupling)是近年来欧洲铁路部门提出的一个新理念,它使用无线通信代替机械联挂,实现不同型号列车的虚拟编组。列车虚拟编组后,行车间隔极大缩短,能够进一步提高线路的运输能力。介绍虚拟编组的研究背景和基本理念,分析既有欧洲列控系统(ETCS)在应用该技术时面临的问题,旨在提出面向虚拟编组的列控技术实现方案。根据列车间隔控制是否由列控系统进行防护,提出两种方案,并描述它们的基本原理和既有ETCS规范需要变动的内容。在基于列控系统防护的方案中,引入相对制动距离的概念,并提出一种基于相对制动距离的限速曲线计算方法,为下一代列控系统的研究提供参考。     

浅谈城市轨道交通信号ATS系统与主控牵引供电的接口

介绍了城市轨道交通信号ATS系统与主控接口的牵引供电功能,并着重以广州地铁3号线为现有条件,重点阐述了牵引供电功能在城市轨道交通中的应用及故障处理。     

Three-dimensional numerical analysis of shipping water onto a moving ship using a particle method

The objective of this study was to develop a numerical analysis method based on the moving particle semi-implicit method for simulating shipping water on a moving ship. Towing tests of a very large crude carrier were numerically analyzed for three typical wavelengths. The ship was forced to move in order to express previously measured ship oscillations, and the calculated fluid behavior and the impact pressure on the deck were compared with the experimental results.     

A numerical study of the effects of bottom and sidewall stiffeners on sloshing behavior considering roll resonant motion

In the present study, aiming to provide practical guidance for the structural design, the effects of the small bottom and sidewall stiffeners on sloshing loads in shallow and intermediate liquid conditions are investigated numerically. The interaction between the highly nonlinear free surface flow and a large number of small stiffeners is modeled based on the Moving Particle Semi-implicit method. 2D models of a rectangular clean tank and tanks with small sidewalls or bottom stiffeners are considered. For filling ratios ranging from 5% to 20%, harmonic angular motions with periods around the analytical sloshing resonant ones are applied. Simulation snapshots and computed pressure time series, pressure variation, wave run-up, maximum fluid velocity, and kinetic energy were provided to clarify the complex interaction between the small baffles and the shallow free surface flow. As a result, except for the tanks with bottom stiffeners in shallow liquid conditions, in which the response under actual resonant frequency should be considered, the response computed using the clean tank excited by its resonant period can be adopted as a conservative estimation for the sloshing loads of actual tanks with small stiffeners.