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20多年来,我国异形掘进机技术得到长足发展。首先,以异形掘进机领域的阶段性科研项目为主线,回顾我国异形掘进机技术从模仿跟随到同步突破再到创新引领的发展历程及所取得的成就,从异形掘进机全断面开挖技术、异形管片拼装技术、测控技术和施工技术等方面介绍我国异形掘进机技术的发展现状; 然后,通过大量案例分析,分别介绍矩形顶管机、矩形盾构、马蹄形盾构及其特殊施工技术在我国隧道建设中的应用情况; 最后,从地质适应性、施工效率、隧道截面形式等方面指出当前异形掘进机发展的局限性,并提出进一步的研究方向,同时对未来异形掘进机在新领域的应用提出几点思考。 相似文献
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Steam generator passive heat removal system (SG-PHRS) is used as a passively safe mode to provide decay heat removal in some advanced pressurized water reactors. Due to the structure characteristics of steam generator (SG), there are two natural circulation loops coupling in SG-PHRS in case of a safety-related event. The existing natural circulation scaling criteria could be used to simulate the natural circulation inside SG. Two-phase natural circulation loop is studied carefully, and the dominant effects of SG on behaviors of natural circulation in passive heat removal system are presented. Based on the understanding of SG-PHRS operation, system pressure transient scaling and two-phase natural circulation scaling are analyzed by establishing the relevant continuity, integral momentum and energy equations in one-dimensional area-averaged forms. With modified equations, similarity criteria for SG-PHRS are obtained for engineering application. In addition, equal height simulation and reduced height simulation are studied. 相似文献
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The research on microfluidic droplet size prediction has been extensive and fruitful, while the droplet deforming process has been seldom studied. In this paper, a frying-oil-assessing microfluidic device was designed to study the droplet deforming and recovering processes, which were dominated by channel geometry, flow rates, sheath flow viscosity and interfacial tension of the two phases. Theoretical expressions of the deforming process and its extreme value were obtained for the first time, supported by simulation and experiments. Theoretical, simulation and experimental results indicated that the steady-state droplet length could be a useful parameter for frying oil assessment. 相似文献
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