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71.
72.
This paper analyses nonlinear dynamics of cable towed body system. The cable has been modeled and analyzed using a new nodal position finite element method, which calculates the position of the cable directly instead of the displacement by the existing finite element method. The newly derived nodal position finite element method eliminates the need of decoupling the rigid body motion from the total motion, where numerical errors arise in the existing nonlinear finite element method, and the limitation of small rotation in each time step in the existing nonlinear finite element method. The towed body is modeled as a rigid body with six degrees of freedom while the tow ship motion is treated as a moving boundary to the system. A special procedure has been developed to couple the cable element with the towed body. The current approach can be used as design tool for achieving improved directional stability, maneuverability, safety and control characteristics with the cable towed body. The analysis results show the elegance and robustness of the proposed approach by comparing with the sea trial data. 相似文献
73.
兼顾景观功能的人工湿地植物配置模式探讨 总被引:4,自引:1,他引:3
湿地植物是人工湿地的重要组成部分,在水质净化过程中起着非常重要的作用,同时也是形成湿地景观的重要要素,目前人工湿地植物的配置还存在着功能结构单一、种间搭配不合理、季相效果差、岸带植物配置效果不佳等问题,影响植物的生态功能及景观效果。通过对湿地植物群落结构特征的研究,借鉴园林中植物造景,提出将植物净化功能与景观特性相结合的设计构想,并提出空间尺度与时间尺度相结合的植物配置模式及将人工湿地的水体与岸带植物配置相结合的人工湿地植物景观设计方式,这将有利于充分发挥人工湿地的多功能效益。 相似文献
74.
National ‘green growth’ strategies, which aim at decoupling economic development from adverse environmental impacts, have become a new paradigm for policymakers in developing countries. Many green growth strategies are based on policy instruments designed to incentivize the domestic deployment of relatively mature clean technologies and aim at fostering the formation of a local industry to develop and produce these technologies. While the empirical evidence on the localization effect of such policies in developing countries is mixed, there is a dearth of research systemically analyzing how differences between technologies affect patterns of localization, which could explain the observed variance. We address this gap and develop a typology which distinguishes four types of technologies requiring different types of capabilities. We do so by combining insights from the literature on technology transfer and catching-up of industries with insights from the literature on patterns of innovation across the technology life- cycle. We apply this typology to the case of low-emission development strategies and four exemplary low-carbon technologies, namely small and micro hydro power, wind turbines, electric cars, and solar cells, in order to analyze capability requirements, innovation patterns, and the effect of past deployment policies on industry localization. We synthesize these case studies and derive a heuristic to anticipate the localization effects of deployment policies for different types of technologies in countries with varying income levels. We argue that the heuristic can serve as starting point for policymakers aiming at clean technology industry localization. The paper concludes with a discussion of possible technology-specific green growth strategies for developing countries with different income levels and for international institutions supporting green growth. 相似文献
75.
76.
遥控水下机器人脐带缆收放绞车设计及牵引力分析 总被引:1,自引:0,他引:1
脐带缆收放技术是有缆遥控水下机器人的一项关键技术,该技术直接影响水下机器人载体的收放及作业过程中脐带缆的安全。针对目前水下机器人收放系统中脐带缆收放技术的特点,给出了一种具有自动排缆、低张力缠绕、能够提供大牵引力和安全制动功能的紧凑新式脐带缆绞车方案,并对牵引绞车与储藏绞车之间脐带缆张力与牵引绞车的牵引力进行了理论分析,给出了二者之间的关系函数。 相似文献
77.
78.
简要介绍了琼州海峡500 kV海底电缆地形地貌特点及保护方式,分析了侧扫声呐及多波束检测的基本原理,对侧扫声呐在海底电缆裸露及悬空检测的原理进行了重点阐述。结合海南联网500 kV海底电缆近几次检测数据,通过侧扫声呐地貌检测结果,重点对海底电缆裸露情况、抛石坝及铸铁套管保护状况、海底电缆周围异常进行了分析,能够正常检测出海底电缆的裸露、抛石坝的坍塌及周围异物等异常情况。通过多波束地形检测结果,分析了海底电缆路由区域整体地形状况及抛石坝整体状况、通过Kriging插值方法生成不同的DEM(数字高程模型,Digital Elevation Model),分别从宏观和微观角度对海底电缆路由区域地形冲淤变化进行了分析,并对沙波稳定性进行了分析。结论认为,部分区域地形冲刷严重,容易造成海底电缆裸露、悬空,需要及早关注并采取防冲刷措施。 相似文献
79.
The drag-induced damping in a mooring cable due to combined first- and second-order wave excited motion of a moored vessel has been determined by statistical linearisation. A dynamic stiffness approach developed elsewhere is used to deal with the dynamics of the mooring cables. The power spectral densities of low- and wave-frequency responses are obtained which clearly show the influence of mooring line damping. The non-Gaussian probability density functions (pdf) and expected crossing rates of vessel responses and dynamic cable tensions are determined using the Kac–Seigert technique, and the influence of drag damping is highlighted. 相似文献
80.
The international submarine cable industry is a major component of the global telecommunications system, providing important services and requiring increased levels of protection for the maintenance of global economic and maritime security, broadly defined. An overview is given of the submarine cable industry, including its technological developments, legal aspects, security considerations, and implications for integrated ocean planning and management. In the context of multiple ocean use, submarine cables can cause spatial conflicts with other ocean users, particularly the fishing industry. Issues to be examined include compensation for lost or damaged gear, legal liability for cable damage, and regulation and licensing of cables on the seabed of the continental shelf and the high seas. Recent industry-to-industry agreements and programs for compensation to fishers in the USA and Canada are significant advancements in the implementation of integrated approaches to ocean management and planning. The development of transparent and stable interdepartmental processes for the coordinated planning, management and regulation of submarine cables is required for national EEZs. The regulation of international cable industry practices must be harmonized with national management approaches. 相似文献