管道超声导波检测技术

介绍了管道超声导渡检测技术的理论基础，指出了这一检测方法的技术关键；同时对现有已用于工程应用的导波检测设备与导渡检测实验系统作了描述和对比；总结了目前成熟的缺陷识别定位方法，在此基础上，对管道超声导波检测技术的广泛应用提出几点展望。     

The Economics of Using Ocean Observing Systems to Improve Beach Closure Policy

Beach closure policies in the United States suffers from two shortcomings. Type I errors, in which clean beaches are closed, results when managers resort to extensive beach closures because they are unsure of the spatial extent of water contamination. Type II errors, in which contaminated beaches remain open, occur because the time from sampling to public notification can be between two and nine days. Coastal Ocean Observing Systems (COOS) could reduce the impact of both Type I and II errors. The COOS could reduce the spatial extent of beach closures by better predicting the fate of contaminants in coastal waters. An improved COOS also could reduce the time from sampling to public notification of contamination events. I estimate the lost recreational value associated with Type I errors (unnecessary closures) and the public health costs associated with Type II errors (unnecessary exposure to waterborne illnesses) for beaches in Southern California.     

Development of a new time domain-based algorithm for train detection and axle counting

This paper presents an innovative train detection algorithm, able to perform the train localisation and, at the same time, to estimate its speed, the crossing times on a fixed point of the track and the axle number. The proposed solution uses the same approach to evaluate all these quantities, starting from the knowledge of generic track inputs directly measured on the track (for example, the vertical forces on the sleepers, the rail deformation and the rail stress). More particularly, all the inputs are processed through cross-correlation operations to extract the required information in terms of speed, crossing time instants and axle counter. This approach has the advantage to be simple and less invasive than the standard ones (it requires less equipment) and represents a more reliable and robust solution against numerical noise because it exploits the whole shape of the input signal and not only the peak values. A suitable and accurate multibody model of railway vehicle and flexible track has also been developed by the authors to test the algorithm when experimental data are not available and in general, under any operating conditions (fundamental to verify the algorithm accuracy and robustness). The railway vehicle chosen as benchmark is the Manchester Wagon, modelled in the Adams VI-Rail environment. The physical model of the flexible track has been implemented in the Matlab and Comsol Multiphysics environments. A simulation campaign has been performed to verify the performance and the robustness of the proposed algorithm, and the results are quite promising. The research has been carried out in cooperation with Ansaldo STS and ECM Spa.     

A real-time impact detection and diagnosis system of catenary using measured strains by fibre Bragg grating sensors

This paper describes an impact detection system using strain signals based on fibre optic sensors(FBG) for the real-time monitoring of the catenary system. The proposed detection system consists of three subsystems: a measuring system, a data processing and analysis system, and a status display and data access system. Because the strain signals obey the normal distribution, to monitor the catenary system in real time, a novel method that combines mobile standard deviation with the mobile Pauta criterion is proposed to distinguish real impact from the strain signal background. The use of this adaptive judging method reduces the misjudgment rate of impacts and improves the impact recognition accuracy. These impacts can be identified by the data analysis system, which provides impact location and their causes using the features of the catenary system. This method can simplify the detection system compared with the traditional location method. An application to a commercial metro line system indicated that the impacts on the catenary system were main caused by overlaps, expansion joints or steady arms, and were verified by correspondence with the floor plan of the catenary and manual inspection results. These results verified the reliability and effectiveness of the proposed impact detection system.     

机动管线水底裸管铺设稳管方式分析比较

机动管线由一根根的管子用连接器或自身阴阳头连接而成,与固定管线相比,在结构形式、铺设方法、使用周期等方面有许多不同,其稳管方式具有独特性。对机动管线水底裸管铺设的稳管方式进行分析,建立管线集中压载稳管和均布压载稳管的数学模型,通过力学计算对两种压载方式进行比较,确定管线稳定的最优方式。提出应用均布压载方式的稳管方法并进行对比,探讨更适于机动管线的水底铺设形式。     

接触网无交叉式线岔的工作原理与调整方法

针对国内准高速、高速铁路的快速发展及既有提速干线接触网改造的现状,阐述高速铁路接触网无交叉式线岔的工作原理及调整方法。     

移动Ad Hoc网络的安全问题和解决方案

移动Ad Hoc网络的自身特点,使它比有线网络更容易遭受攻击。文章首先分析了威胁移动Ad Hoc网络安全的典型攻击,主要讨论了移动Ad Hoc网络的安全路由技术和入侵检测技术两种安全技术,对一些典型安全方案进行了论述与比较。     

后张预应力梁封端缝渗漏治理

由于后张预应力梁封端混凝土与梁体混凝土的浇注时间不同,形成封端缝,进而造成封端混凝土渗漏并引起锚具锈蚀和预应力的损失,严重影响行车安全．文中提出了一种能在12cm（及以上）的狭窄伸缩缝环境下对封端缝渗漏进行治理的方案．首先改进了适用于该狭窄环境的基面清理工具,通过实验室模拟试验、材料性能测试和数值模拟,证实了本基面清理工具的实用性和本方案的可行性,进而将该方案成功的应用于神朔铁路大柳塔-府谷段6孔梁的现场渗漏治理．为检验治理效果,开发了一种集信号输出与数字采集于一体的渗漏检测仪样机,测试对比表明,样机具有较高的精度和较大的量程,完全可以满足工程需要．     

论轨道交通列车位置检测设备

基于在地铁和单轨中应用的列车位置检测设备,阐述各种列车位置检测设备的基本结构和工作原理,分析其优缺点,同时提出设备选型的建议。     

广州地铁检测设备综合标定线技术设计思路

为规范广州地铁大型基础设施检测设备的运用,基于检测设备的配备规划情况,论证综合标定线设置的必要性。结合国内外检测设备的发展和应用现状,参考有关国家标准和铁路行业的技术文件,通过对各检测系统检测项目的分析,按照模拟真实检测环境的思路,对标定线进行仿真技术设计,以验证检测系统的检测精度和检出性能。建成的综合标定线可有效保证检测设备符合各项检测项目的技术指标要求,确保检测数据准确、可靠,同时,展望综合标定线的建设与运用,规划标定线建设的可行性方案,以满足检测设备运用的标定需求。