客运专线桥上无缝道岔设计方法研究

研究目的:桥上无缝道岔设计已成为客运专线的关键技术之一.目前国内桥上无缝道岔研究刚刚起步,尚未形成系统计算理论和设计方法.开展桥上无缝道岔计算理论和设计方法研究,具有重要理论和现实意义.本文旨在建立一种桥上无缝道岔计算模型和计算方法,提出桥上无缝道岔设计流程和设计方法,探索我国无缝道岔技术发展方向.研究结论:引进技术和自主创新相结合,在消化吸收国外先进设计理念的基础上,初步建立了桥上无缝道岔设计方法和设计体系,为桥上无缝道岔设计提供依据.本文建立的"岔-梁-墩一体化"计算模型能够真实反应道岔和桥梁的相互作用,桥上无缝道岔设计方法具有很强的可操作性,研究成果对于我国客运专线桥上无缝道岔设计和施工有重要指导意义.     

机车车辆与线路最佳匹配设计原理、方法及工程实践

提出了采用系统设计思想实现机车车辆与线路最佳匹配设计的理念,论述了匹配设计的基本原理与设计方法。指出:机车车辆系统和线路系统在动态性能设计上要相互适应、相互匹配。无论设计主体对象是机车车辆还是线路,都必须将对方视为主体对象的动态环境,通过机车车辆—轨道耦合动力学理论方法考虑对方的动态影响因素,进行主体对象动力性能优化设计,同时分析评估主体设计对象对另一系统的动态作用影响,再根据动态作用影响的评估结果改进主体对象结构设计参数,如此反复,直到整体系统动态性能最优为止。由此开发了机车车辆—轨道耦合动力学仿真设计技术平台。经在若干铁路重大工程线路设计中运用,取得了显著成效。     

Propagation and origin of warm anomalies in the Angola Benguela upwelling system in 2001

Warmer than average sea surface temperatures were observed by the Tropical Rainfall Mission Microwave Imager in the Angola Benguela Current system in late austral summer 2001 and persisted for about three months. These coastal anomalies extended offshore by 1 to 4° longitude and were not due to local ocean atmosphere interaction or relaxation of the upwelling favorable southerly winds. Instead, they were remotely forced by ocean atmosphere interaction in the Tropical Atlantic. Satellite remote sensing and a linear ocean model suggest that relaxation of trade winds along the equator triggered Kelvin waves that crossed the basin within a month in early 2001. Westerly wind anomalies were also observed in December 2000 and January 2001 over most of the Tropical Atlantic contributing to a warm preconditioning due to an enhancement of the oceanic annual cycle. This led to abnormal sea level heights near equatorial Africa that propagated southwards along the coast towards the Angola Benguela Frontal zone. This process increased the seasonal penetration of warm and salty water of tropical origin into the Angola Benguela upwelling system.     

高速轮轨接触几何关系的比较分析

高速轮轨接触几何关系研究涉及诸多因素。选择中国车轮踏面LMA与钢轨CHN60、日本新干线圆弧车轮踏面JP-ARC与钢轨JIS60和欧洲标准车轮踏面S1002与钢轨UIS60,比较这3种轮轨关系的几何参数差异,编制了轮轨接触几何的数值分析软件,计算不同轮对内侧距情况下的轮轨接触几何关系,比较在轮对内侧距为1353和1360mm情况下,轮对横移时的滚动圆接触半径差和接触角差的数值计算结果,探讨适应于我国高速车轮踏面形状和轮对内侧距,为高速轮轨关系的深入研究提供基础。     

Interaction of HLA and TCP/IP subsystems in C^3I system

Aiming to the fact that the distribution modules of the C31 simulation system originally developed based on TCP/IP protocol has to be compatible with the present HLA （High Level of Architecture） rules, three methods for implementing the interaction of HLA and TCP/IP subsystems are presented to make the original TCP/IP modules directly used in the HLA-based C^3I system without redevelopment. The three methods are agent method, middlewarc method and gateway method. Moreover, the implementation of gateway method via VC ＋＋ as well as the key technology is discussed.     

Modification of the semi-Hertz wheel–rail contact method based on recalculating the virtual penetration value

ABSTRACT

Wheel–rail contact calculation is of vital importance in vehicle system dynamics. In the existing methods of wheel–rail contact calculation, the finite element method and Kalker’s CONTACT program, which are based on the complementary energy principle, are the two methods with accuracy recognised. However, because of its very slow calculation speed, it cannot meet the requirement of online calculation, so a variety of fast non-elliptic algorithms have been proposed. The semi-Hertz method, which is recognised for its great contributions to the fast wheel–rail contact calculation, is based on the concept of virtual penetration. The calculation of virtual penetration is crucial to evaluate the shape and normal pressure distribution of the contact patch. In practice, the virtual penetration is related to the curvature of the whole contact patch; however, the range of the contact patch is determined by the value of penetration. Such an interaction leads the calculation into a dead loop. In the semi-Hertz method, the penetration is calculated by the Hertz parameters of the initial contact point. Thus, the practical range of the method is limited. In this paper, a fast-iterative method for solving virtual penetration is proposed, and a reliable value of virtual penetration can be obtained under any lateral wheel–rail relative curvature variation with good stability and speed. The normal and tangential solutions are analysed with different methods in this paper.     

A structural articulation method for assessing railway bridges subject to dynamic impact loading from track irregularities

This paper discusses the importance of track irregularities in railway bridge design, and presents a new technique for calculating the dynamic impact load induced by such irregularities: the structural articulation method. The properties of the combined bridge-suspension system are coupled through global mass, stiffness, and damping matrices. Under the proposed method, the true suspension system over a particular point on the bridge girder at time t is divided into equivalent suspension systems attributed to adjacent finite-element nodes of the bridge. The time-dependent effects of a moving mass are thereby included in the equation of motion.     

Interaction study of train–bridge–track systems using Maxwell model

The investigation of problems related to the interaction of train, bridge and track systems has been accelerated by the emergence of high-speed trains. Such studies are required, not only for the endurance issues regarding bridge and tracks, but to assure trains’ functionality and performance. The suspension mechanism of train systems is of prime importance in defining the functionality of high-speed trains, and accurate mathematical models of the mechanism are imperative. This paper introduces a numerical technique for an interaction study of train–bridge–track systems based on Maxwell (three-element type) modeling of the suspension mechanisms of vehicles. Track irregularity in sinusoidal form is also integrated into the mathematical model. Although the proposed technique is simple in formulation, it offers phenomenal accuracy in representing the interaction of train, track and bridge systems. In a numerical example, the dynamic behavior of a train–bridge system has been studied. Results of this analysis provide a valuable insight into the contributing roles of different parameters in this subject.     

Derivation of plastic framing requirements for polar ships

A new International Association of Classification Societies standard for polar ship design, in the form of a unified requirement is being developed by an international committee with representatives from many classification societies and with the active participation of many polar nations. The framing structural requirements have been developed by a combination of analysis of existing rules and ships, finite element (FE) analysis and analytical solutions of plastic collapse mechanisms. This paper describes the derivation of the 3-hinge and asymmetrical shear plastic collapse mechanisms using work–energy principles. Energy methods are robust and well suited for developing design standards. The results are shown to compare well with non-linear FE analyses of frame strength.     

准三维波生近岸流数学模型在裂流研究中的应用

阐述了一种考虑波流耦合作用的准三维近岸流模型SHORECIRC。该模型耦合了REF／DIF波浪模型（折／绕射模型）对近岸流进行模拟计算。基于该模型，将模拟结果与Borthwick等人在英国海岸工程研究所做的实验进行对比，验证了模型的正确性和适用性。在此基础上，进一步分析了波浪入射波高、入射角度、底摩阻及驼峰高度对裂流的影响，得出了一些有用的结论。