频率变化对连杆动态应力的影响研究

通过试验研究验证了连杆有限元仿真模型的精确性,进一步研究了加载频率变化对连杆动态应力的影响,得到了加载频率变化对连杆动态应力的影响规律.结果表明:在加载频率较低时,连杆动态应力会随着加载频率的增加而增大,但总体来说应力值增加不大,可以忽略;在加载频率较高时,加载频率对连杆动态应力的影响很大,不可忽略.     

Inverse identification of wheel–rail contact forces based on observation of wheel disc strains: an evaluation of three numerical algorithms

In this paper, three numerical algorithms for the identification of wheel–rail contact forces based on measured wheel disc strains on an instrumented railway wheelset are discussed and compared. The three algorithms include one approach resting on static calibration, one that is applying a Kalman filter and the third is exploiting an inverse identification scheme. To demonstrate and evaluate the alternative methods, two load cases including periodic excitation by sinusoidal wheel–rail irregularities and transient excitation by an insulated rail joint are considered. Based on a previously presented vehicle–track interaction model in the time domain, load scenarios are defined by taking the calculated vertical wheel–rail contact forces as the reference force to be re-identified by the proposed algorithms. The reference contact forces are applied on a finite element model of the wheel to generate synthetic observation data, that is, radial strains at the positions of the strain gauges, serving as input to the identification procedures. It is concluded that the inverse identification scheme leads to superior accuracy at higher computational cost. If on-line implementation and evaluation is required, the Kalman filter generates better accuracy than the static calibration approach.     

基于HMM的客车转向架故障诊断与应用

介绍隐马尔可夫模型（HMM）算法在转向架故障诊断中的应用.利用HMM方法研究转向架在运行过程中抗蛇行减振器正常、异常状态,HMM的参数根据试验数据统计训练出,提出了一种新的转向架故障诊断方法,试验证明该诊断方法可行.     

Theoretical analysis of natural frequency of externally prestressed concrete beam based on rigidity correction

A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at,the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the experimental beams are calculated, and big errors are found between the test results and the calculated ones of natural frequency values. As a result, this paper has tried to adopt two methods to correct the rigidity parameter of the concrete beam in the formula for natural frequency calculation, and to use the corrected formula to calculate the frequencies of the experimental beams. The calculation results indicate a good consistency with the experimental ones, which verifies the feasibility of the corrected formula.     

基于GIS的交通污染扩散模拟

利用GIS技术建立机动车污染仿真模拟系统，能够直观反映机动车污染的时空分布规律，为机动车污染控制研究提供有力的工具。以ArcGIS Engine为开发工具，通过属性数据和空间数据的连接，实现了武汉市机动车污染的数据查询和空间显示等功能，通过GIS和高斯扩散模型的集成，分析了武汉市交通污染分布，为机动车污染的控制提供了技术支持。该系统能对武汉市机动车污染物的排放进行实例分析。     

金属带式无级变速器控制任务的分解

将无级变速器的控制任务按执行顺序分解为工况识别、控制策略设计和系统执行3个层次,并将工况识别再细分为驾驶员意图识别、车辆环境识别和传动系统状态识别3类.以电液控制系统为例的分析表明,控制任务的分解,减少了需要处理的工况数量.文中提出的方法大大减少了控制系统设计的工作量,缩短了控制系统分析调试时间.     

铁路站段系统VPN组网与应用

随着信息技术的发展，铁路各站段系统越来越需要加快内部信息流转速度，提高生产管理效率，因此在既有铁通宽带网络的基础上，提出采用ADSL技术为主要接入手段，利用公众互联网为铁路局各站段组建VPN网络的技术方案。     

计轴闭塞区段单轨条移频机车信号不上码或上红码的问题分析

通过对计轴单轨条移频区段因车速原因造成机车信号不上码或上红码问题分析,提出了具体的解决方案。     

复杂悬跨条件下的管线涡激振动分析(英文)

Spans occur when a pipeline is laid on a rough undulating seabed or when upheaval buckling occurs due to constrained thermal expansion. This not only results in static and dynamic loads on the flowline at span sections, but also generates vortex induced vibration (VIV), which can lead to fatigue issues. The phenomenon, if not predicted and controlled properly, will negatively affect pipeline integrity, leading to expensive remediation and intervention work. Span analysis can be complicated by: long span lengths, a large number of spans caused by a rough seabed, and multi-span interactions. In addition, the complexity can be more onerous and challenging when soil uncertainty, concrete degradation and unknown residual lay tension are considered in the analysis. This paper describes the latest developments and a .state-of-the-art. finite element analysis program that has been developed to simulate the span response of a flowline under complex boundary and loading conditions. Both VIV and direct wave loading are captured in the analysis and the results are sequentially used for the ultimate limit state (ULS) check and fatigue life calculation.     

小波变换在结构损伤识别中的应用研究

针对土木工程结构的复杂性和数据的不完备性，以小波分析为理论基础，结合多尺度分析理论和数值模拟，对结构损伤识别进行了研究。主要分析了结构动力参数在损伤后的变化特征，对单自由度框架的加速度信号进行小波分析，得到结构损伤的时刻；研究了利用空间域信息对结构损伤位置的识别问题，对带裂缝悬臂梁的变形曲线进行小波变换，判定了结构损伤位置。