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为了研究定标点失效对管道中心线坐标及应变数据的影响,文中以管道环焊缝作为特征点对比2次中心线检测的环焊缝球面距离和管道应变数据,研究定标点失效情况下数据偏差情况。结果表明:对于1 km/点设置定标点时,环焊缝位置的偏差能保持在2 m范围内,对于1~2个定标点失效时环焊缝偏差会扩大到5 m,对于连续5点定标点失效时,环焊缝位置的偏差会超过14 m,该坐标数据已失效;对于极限情况连续5个定标点失效的情况下,通过环焊缝仍然可以将2次检测应变数据进行对齐,且检测数据能够良好复核,对于连续5个定标点失效情况下应变数据仍准确有效。 相似文献
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针对南海某油田平台间某双层海底管道的外管发生一处断裂失效事故,根据管道实际运行工况,考虑土壤摩擦力对外管的作用,利用有限元接触分析方法进行双层海管的受力分析,结合DNV规范对管道进行强度校核。结果显示:利用有限元接触算法来分析管土相互作用时,采用刚性面来模拟土壤层是可行的;在未超过原设计压力和设计温度条件下,该海管的外管将不会发生断裂失效事故,管道满足结构强度要求;若海管产生较严重的局部腐蚀,最严重腐蚀点的缺陷凹坑深度超过壁厚的85%,将会发生断裂失效事故。 相似文献
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文中以弥陀输气站21#双作用节流截止阀失效为基础,分析生产运行工况,模拟气体流向和流态,分析失效过程。结果表明:高速天然气流过阀门时,因流道发生改变,在下阀腔内形成涡流,对阀门底座法兰与阀体密封面形成冲刷,导致阀门失效和天然气泄漏。根据失效原理制定预防控制措施,防止失效事故发生。 相似文献
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Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD). An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip. It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links. 相似文献
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Joseph N. Prashker 《Transportation》1979,8(4):329-346
Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area. 相似文献
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This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress. 相似文献
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本文阐述了混合动力列车的技术特点及其相应优势与劣势,同时介绍了其在国内外的研究动向,并对其应用前景进行了展望。尽管该类新型铁道车辆的续航能力、电池寿命以及成本等相关问题目前仍有待改善,但以其对城市环境的美化作用与优越的舒适驾乘性能,以及高效节能、绿色环保的显著优势,依然不失为一类充满前景的新型轨道交通运输方式。 相似文献
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天然气自动计量系统有多种组态软件,由于软件的不相通性,造成了计量系统数据采集的通用性差、数据传输与入库的时效性差、数据利用的可靠性低.结合各组态软件的实际情况,从设计上充分利用Oracle大数据处理能力以及Partition(分区表)的特性,实现历史数据的存储,应用WebService与COM+数据访问组件提供多层数据访问架构,采用OPC与DDE工业数据交换协议,实现了各站场计量数据的实时上传,为连续数据采集和实时监控提供了可能,节约了改造成本. 相似文献
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介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。 相似文献