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随着液化天然气(LNG)项目的不断发展,新型的管道保冷材料被广泛应用。文中结合某LNG项目管道柔性保冷材料的实际施工情况,对柔性保冷材料的施工工艺从环境要求、保冷结构、施工顺序等几个方面进行研究,总结出了最适合的保冷施工工艺,为其他LNG项目管道保冷材料的选型提供参考,为管道保冷施工提供参考。 相似文献
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文中介绍了GMAW自动焊在工厂管道预制中的应用,比较了与其他焊接方法的优缺点。阐述了GMAW自动焊所需要的设备、工艺要求。详细介绍了保护气体、熔滴过渡形式、焊接住置对焊接的影响。以2种常用材料SAl06Gr.B和304L为例,对坡口准备,所用焊材、电流、电压、保护气做了详细的说明,同时指出在工厂GMAW自动焊接工程中应注意的问题。对采用该种工艺的焊缝进行力学性能试验,各项指标均符合标准要求,完全满足实际生产的需要。 相似文献
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压力管道的工况分析及其对材料性能的要求 总被引:1,自引:0,他引:1
针对压力管道在安装和使用中具有复杂性和特殊性的特点,对压力管道可能遇到的不同的工况条件进行了详细的分析,并据此提出了压力管道对所选用材料性能的一些特殊要求.结合典型压力管道的选材分析,分别以高温管道和低温管道为例,说明为保证装置的安全、稳定、可靠和长周期运行,压力管道在选材时需考虑的因素.同时,指出在选材时必须坚持的原则,具有一定的实际工程意义. 相似文献
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输油管道大落差线路有超压和泄漏两个特殊问题,在可装拆型管道和管径较小的固定型成品油管道上应用自力式减压站是一种理想的处置方法,文中综合了国内外自力式减压站所采用的技术,并从理论与实践上进行了分析与评价,着重介绍了近年来新研制成的体积小,质量轻的新型自力式减压站,阐述了压力自动调节,超流自动截断并禁开,压力自动开启,涨油自动卸压等诸功能的工作原理,说明了它的必与结构特点,最后,以新型减压站为例,描述 相似文献
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在公路工程施工过程中,材料及设备的使用费用在整体工程成本中所占比例很大,从工程材料的数量控制、工程材料的采购控制、工程质量控制、工程材料使用控制及材料预算合理控制和采购材料的局限与问题等方面进行阐述,论述材料管理在公路工程中的重要性,以期为相关工作人员提供参考。 相似文献
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腐蚀严重的各种管线的不开挖修复已经成为恢复旧管线功能,延长使用寿命的有效途径。本文提出了以聚乙烯为代表的塑料管缩径穿插,环空顶替水泥浆分步阶段完成的技术方案,并就填充材料1 空顶替技术及施工中应注意的问题撮了几点意见。 相似文献
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相信自己是一只雄鹰
一个人在高山之巅的鹰巢里抓到一只幼鹰,他把幼鹰带回家养在鸡笼里.这只幼鹰和鸡一起啄食、嬉闹和休息.它以为自己是一只鸡. 相似文献
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《Transportation Research Part A: Policy and Practice》2007,41(4):339-350
This paper describes the development of a mode choice model for the journey to work with special emphasis on the propensity to cycle. The model combines Revealed Preference (RP) and Stated Preference (SP) data to form a very large and comprehensive model. RP data from the National Travel Survey was combined with a specially commissioned RP survey. A number of SP surveys were also undertaken to examine the effects of different types of en-route and trip end cycle facilities and financial measures to encourage cycling.The development of the model is described in detail. The model was used to forecast trends in urban commuting shares over time and to predict the impacts of different measures to encourage cycling. Of the en-route cycle facilities, a completely segregated cycleway was forecast to have the greatest impact, but even the unfeasible scenario of universal provision of such facilities would only result in a 55% increase in cycling and a slight reduction in car commuting. Payments for cycling to work were found to be highly effective with a £2 daily payment almost doubling the level of cycling. The most effective policy would combine improvements in en-route facilities, a daily payment to cycle to work and comprehensive trip end facilities and this would also have a significant impact on car commuting. 相似文献
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近年来,铁路客运”夕发朝至”、“朝发夕至”、“直达特快”及旅游专列等品牌列车的不断推出.城际列车的开通.使具有传统优势的长途、中短途客运的道路运输企业经营压力相应加大。旅客出行也开始有越来越多的选择机会.市场竞争不再是单一的价格与技术竞争. 相似文献
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偶尔翻翻报纸,看到不少各地有关去年治超成绩的通报,大凡是检查了多少超载车辆,卸载了多少吨超载货物,罚款累计多少元,超载率下降了多少. 相似文献
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《Transportation Research Part A: Policy and Practice》2007,41(9):842-856
Using a range of nonparametric methods, the paper examines the specification of a model to evaluate the willingness-to-pay (WTP) for travel time changes from binomial choice data from a simple time–cost trading experiment. The analysis favours a model with random WTP as the only source of randomness over a model with fixed WTP which is linear in time and cost and has an additive random error term. Results further indicate that the distribution of log WTP can be described as a sum of a linear index fixing the location of the log WTP distribution and an independent random variable representing unobserved heterogeneity. This formulation is useful for parametric modelling. The index indicates that the WTP varies systematically with income and other individual characteristics. The WTP varies also with the time difference presented in the experiment which is in contradiction of standard utility theory. 相似文献
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