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991.
P. Weston G. Yeo E. Stewart 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2015,53(7):1063-1091
This paper presents a view of the current state of monitoring track geometry condition from in-service vehicles. It considers technology used to provide condition monitoring; some issues of processing and the determination of location; how things have evolved over the past decade; and what is being, or could/should be done in future research. Monitoring railway track geometry from an in-service vehicle is an attractive proposition that has become a reality in the past decade. However, this is only the beginning. Seeing the same track over and over again provides an opportunity for observing track geometry degradation that can potentially be used to inform maintenance decisions. Furthermore, it is possible to extend the use of track condition information to identify if maintenance is effective, and to monitor the degradation of individual faults such as dipped joints. There are full unattended track geometry measurement systems running on in-service vehicles in the UK and elsewhere around the world, feeding their geometry measurements into large databases. These data can be retrieved, but little is currently done with the data other than the generation of reports of track geometry that exceeds predefined thresholds. There are examples of simpler systems that measure some track geometry parameters more or less directly and accurately, but forego parameters such as gauge. Additionally, there are experimental systems that use mathematics and models to infer track geometry using data from sensors placed on an in-service vehicle. Finally, there are systems that do not claim to measure track geometry, but monitor some other quantity such as ride quality or bogie acceleration to infer poor track geometry without explicitly measuring it. 相似文献
992.
基于动力学基本原理,从非线性、接触以及本构关系计算理论建立落石-桥墩防撞物柔性碰撞精细化计算模型,并对关键计算参数给出建议取值.利用钢结构柔性变形吸收落石碰撞能量,提出一种桥墩防落石碰撞柔性设计方法,并详细给出该防落石碰撞构造措施的结构组成形式.利用ANSYS/LS-DYNA动力分析计算程序,考虑几何、材料双重非线性,精细化数值仿真计算落石撞击防撞物的动态全过程,以一个偏安全的极限碰撞状态,分别从运动行为(撞击力、位移、速度、加速度)以及能量转换(系统动能、系统变形能)角度进行计算结果与数据分析,证明所提出的柔性防撞设计思路以及防撞措施的合理性与优越性. 相似文献
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994.
On November 30, 2006, USS Boone (FFG 28) lost all steering control in the Mediterranean Sea due to a lost rudder. Within hours of the casualty, numerous US Navy and contractor activities sprung into action to coordinate and complete an emergent voyage repair to return USS Boone to service to support the Global War on Terrorism. The Navy faced a large hurdle to identify and transport a replacement rudder to Rota, Spain, and prepare and carry out an extremely complex repair procedure. Pearl Harbor Naval Shipyard personnel removed the replacement rudder from USS Crommelin (FFG 37) in Pearl Harbor Naval Shipyard and transported the rudder to Rota, Spain. The Navy's Supervisor of Salvage and Diving developed the repair procedure and coordinated the repair operation, which involved over 30 US Navy and contractor divers. The repair team completed the rudder replacement on December 28, 2006 and returned USS Boone to underway operations. 相似文献
995.
上海航运交易所信息部 《集装箱化》2007,18(4):40
受农历新年影响,春节期间中国出口集装箱运输市场货量明显萎缩,尽管节后逐渐恢复,但各航线恢复情况不一,市场运价走势存在差异。3月16日,上海航运交易所发布的中国出口集装箱综合运价指数为1026.07点,较上月同期基本持平:上海地区出口集装箱运价指数为1025.79点,较上月同期微涨1.5%。 相似文献
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Error quantification of a high-resolution coupled hydrodynamic-ecosystem coastal-ocean model: Part 2. Chlorophyll-a, nutrients and SPM 总被引:1,自引:0,他引:1
J. Icarus Allen Jason T. Holt Jerry Blackford Roger Proctor 《Journal of Marine Systems》2007,68(3-4):381-404
Marine systems models are becoming increasingly complex and sophisticated, but far too little attention has been paid to model errors and the extent to which model outputs actually relate to ecosystem processes. Here we describe the application of summary error statistics to a complex 3D model (POLCOMS-ERSEM) run for the period 1988–1989 in the southern North Sea utilising information from the North Sea Project, which collected a wealth of observational data. We demonstrate that to understand model data misfit and the mechanisms creating errors, we need to use a hierarchy of techniques, including simple correlations, model bias, model efficiency, binary discriminator analysis and the distribution of model errors to assess model errors spatially and temporally. We also demonstrate that a linear cost function is an inappropriate measure of misfit. This analysis indicates that the model has some skill for all variables analysed. A summary plot of model performance indicates that model performance deteriorates as we move through the ecosystem from the physics, to the nutrients and plankton. 相似文献
999.
汽车产业和物流产业都是我国“十五”期间重点发展的支柱产业。本文简述了汽车物流的概念,详细分析了国内汽车物流业发展现状,指出了我国汽车物流业存在的问题,并对国内汽车物流业的发展提供了若干建议。 相似文献
1000.