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为了提高在役压力容器管座角焊缝缺陷的检测效率以及缺陷检测的可靠性,文中对在役压力容器管座角焊缝相控阵超声检测方案进行验证。调整了用于在役压力容器管座角焊缝检测的扫查装置,确定了实验方案中实际缺陷长度的计算方法。通过相控阵超声检测扫描获得的图谱,可以对管座角焊缝的典型缺陷进行识别和评定。该研究同时可协助解决管座角焊缝不同类型缺陷的定性分析和定位难题,对管座角焊缝相控阵超声检测图像识别和结果评定有借鉴作用。 相似文献
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采用管道失效评估方法可评估静载荷作用下缺陷是否满足适用要求。但在内压等交变载荷作用下,输油管道环焊缝仍存在疲劳破坏的可能。为评估管道环焊缝缺陷的疲劳寿命,进行管道母材和环焊缝疲劳裂纹扩展速率试验,并分析和统计管道实际运行压力数据以及环焊缝缺陷开挖验证数据,采用BS7910标准方法计算疲劳寿命值。结果显示在仅考虑管道内压波动情况下,管道环焊缝平面型缺陷的疲劳寿命结果满足管道设计使用要求。 相似文献
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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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目前,国内的管道环焊缝数字射线检测设备仅能实现静态成像,曝光时间过长,成像结果由多张图像组成,增加了判读工作量和图像评定难度。管道环焊缝X射线数字成像动态采集系统解决了这些问题,采集面板在电机的驱动下沿着轨道匀速行驶,采集图像无缝无重叠地连续实时显示,最终形成一幅完整的管道焊缝扫查图。针对数字射线动态数据采集系统的TDI原理、TDI扫查的时钟同步源、CMOS平板探测器中偏置电压的刷新和面板校准等问题进行详细说明,完成了X射线数字成像动态采集软件的设计和编程,并在管径813 mm、壁厚12.5 mm的管道环焊缝上进行检测试验,采集图像中缺陷清晰可见。 相似文献
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Recent years have shown a rising popularity of the concept of resilience—both theoretically and empirically—in complex systems analysis. There is also a rising literature on resilience in the transport and spatial-economic field. The pluriform interpretation of resilience (e.g., engineering vs. ecological resilience) is related to methodological differences (e.g., stability in dynamics vs. evolutionary adaptivity). But in all cases the fundamental question is whether a complex system that is subjected to an external shock is able to recover, and if so, to which extent. The present paper [Based on presentation from cluster 6 (Accessibility) of the Nectar 2015 conference in Ann Arbour, USA.] aims to add a new dimension to resilience analysis in spatial systems, by addressing in particular the relationship between spatial accessibility at a municipality level and the resilience outcomes of the spatial system concerned. It does so by investigating to which extent accessibility of Swedish and Dutch municipalities has mitigated the local shock absorption from the recent economic recession. In our study the shock absorption capacity of municipal accessibility is estimated by analysing the relevant resilience indicators for the period concerned. In this context, conventional resilience indicators based on either multivariate complex data (in particular, the Foster Resilience Capacity Index) or employment data (in particular, the Martin Resilience-Employment Index) are confronted with spatial connectivity data based on local accessibility measures, so that geographical mobility may be regarded as one of the shock-mitigating factors. The empirical analysis is carried out for two countries which have both proven to be rather shock-resistant during the recent economic crisis, viz. Sweden and The Netherlands. Clearly, the geographical structure of these countries forms a sharp mutual contrast, viz. a spatially dispersed economy with a few distinct urban concentrations versus a spatially dense economy with one major metropolitan centre (the Randstad), respectively. Our experiments are carried out for the 290 municipalities in Sweden and 40 COROPs in The Netherlands. Our research findings show relevant and new insights into differences in the local recovery potential in Sweden and The Netherlands. 相似文献
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The bicycle is often understood as a disjointed ‘feeder’ mode that provides access to public transport. We argue that combined use of the bicycle and public transport should be understood in a broader perspective, especially where bicycles link to higher speed and higher capacity public transport, such as the train. Cycling and public transport can have a symbiotic relationship forming a hybrid, distinct transport mode, which should be reflected in transport planning. The bicycle is as a way to soften the rigid nature of public transport and thus accommodate diverse individual travel needs and situations. Public transport can be seen as a means to dramatically extend cycling’s speed and spatial reach. We combine a system perspective with conceptual analysis to explore how, why and when this reconsideration is important. We use the Netherlands as illustrative case because of the relative maturity of its bicycle–train connections. The case shows that the synergy between rather opposite yet highly complementary aspects, high speed of the train, high accessibility of the bicycle and flexibility in combining both sub-modes, are the fundamental characteristics to understand the functioning of this system in a wider spatial context. In our conclusion we propose a research agenda, to further explore the relevance of this system for land-use and transport planning and distil wider implications for the international debate. 相似文献
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In modern cities, a rapid increase of motorcycles and other types of Powered Two-Wheelers (PTWs) is observed as an answer to long commuting in traffic jams and complex urban navigation. Such increasing penetration rate of PTWs creates mixed traffic flow conditions with unique characteristics that are not well understood at present. Our objective is to develop an analytical traffic flow model that reflects the mutual impacts of PTWs and Cars. Unlike cars, PTWs filter between cars, have unique dynamics, and do not respect lane discipline, therefore requiring a different modeling approach than traditional “Passenger Car Equivalent” or “Follow the Leader”. Instead, this work follows an approach that models the flow of PTWs similarly to a fluid in a porous medium, where PTWs “percolate” between cars depending on the gap between them.Our contributions are as follows: (I) a characterization of the distribution of the spacing between vehicles by the densities of PTWs and cars; (II) a definition of the equilibrium speed of each class as a function of the densities of PTWs and cars; (III) a mathematical analysis of the model’s properties (IV) an impact analysis of the gradual penetration of PTWs on cars and on heterogeneous traffic flow characteristics.The proposed model could contribute as an enabler for ‘PTW-aware’ future Cooperative Intelligent Transport Systems technologies and traffic regulations. 相似文献
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《综合运输》2020,(1)
智能系统的广泛使用,带来了移动支付的普及。公交支付在传统IC卡和现金支付的基础上,加入了云闪付和二维码支付。为探究移动支付对公交支付效率的影响,基于杭州市公交发展现状,制定了公交支付情况的调查方案。通过对所选10、93、97公交线路的早、晚高峰和平峰的三天实地调查,采集视频数据并使用SPSS进行定量统计分析,发现公交乘客刷卡占62%、二维码占27%、云闪付占6%、现金占5%。当乘客提前做好准备时,刷卡支付时间为1.29 s,低于云闪付的1.42 s和二维码的1.65 s,而未准备好时用时分别为6.74 s、10.94 s、8.54 s。通过相关性和多元线性回归分析得出"提前拿卡"、"上车掏卡"、"提前开二维码"和"上车开二维码"四种支付方式对公交停留时间延长的影响最大。 相似文献
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