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21.
Slender marine structures such as mooring lines and risers are susceptible to failures due to stress variations coming from environmental actions. Wave, wind and current are random phenomena, and consequently the most adequate methodology to estimate the fatigue damage accumulation on these structures is the probabilistic fatigue analysis. In practice, the estimation of fatigue life requires the numerical simulation of a huge number of loading cases to compute the multi-dimensional integral of the total fatigue damage.This paper presents an efficient approach to compute the long-term fatigue damage of marine structures. The proposed method needs only a few number of numerical simulations to estimate the structure fatigue life. It uses a parametric interpolation procedure to evaluate the fatigue damage for any individual short-term condition (sea state) required in the calculation of the multi-dimensional integral. In this way, the total number of short-term structural analyzes is considerably reduced.The effectiveness and accuracy of the proposed method is compared to the full direct integration by means of two comprehensive examples. The first studied case is an idealized theoretical model of a single-degree-of-freedom (SDOF) system under wave loading, and the second one is a Steel Catenary Riser (SCR) connected to a FPSO (Floating, Production, Storage and Offloading floating unit). 相似文献
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材料表面性质对微生物附着行为的影响 总被引:1,自引:0,他引:1
利用荧光显微镜计数法,研究了微生物在4种不同材料表面的初始附着行为,对微生物附着进行了定量描述,初步获得以下结果:(1)不同材料表面,细菌的附着量呈现如下差异:316L不锈钢>PVC>玻璃,在有机硅材料(道康宁T2)表面的附着变动性很大;(2)同种材料表面,不同细菌的附着量也不同,表现为:Shewanella oneidensis MR-1菌株和Pseudomonas aeruginosa PAO1菌株均大于Escherichia coli JM 109菌株.并由此对其附着差异和影响因素进行了讨论. 相似文献
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本文概要论述了排水管道CIPP拉入法内衬修复技术采用紫外线固化的工艺过程、技术优势;并根据紫外线固化工艺存在的技术缺陷,提出了有针对性的可操作的质量验收方法,希望对管道业主同仁们在紫外线固化工程验收时有所助益,以进一步促进管道非开挖修复事业在我国的健康发展。 相似文献
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In this paper, an elastostatic half-plane boundary element method (BEM) formulation was applied to analyze the stress behavior of underground pressure pipes, embedded in two-layer soils. In the use of this method, only the boundary of pipe and interfaces were required to be discretized. In this regard, first, a computer code was prepared based on a multi-region substructuring process in the BEM scheme. Then, the efficiency and applicability of the method as well as the prepared algorithm were verified by solving some practical examples and comparing the results with those of the published works. Finally, a parametric study was done to evaluate the effect of pipe depth and determine the soil stress distribution. The studies showed that the half-plane BEM was in good agreement with the existing solutions and its capability was very favorable for elastostatic problems including semi-infinite domain. It is obvious that this method can be practically used to analyze the geotechnical underground buildings in substituting the full-plane BEM formulation. 相似文献
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Exploring the dynamic changes of steel from the ships is critical for developing sustainable strategies for waste management of shipping industry. However, the information of stocks and flows of ships and related steel is currently unavailable, hindering the sustainable development of shipping industry. By collecting dispersed information on production, use, material composition, and end-of-life management of five types ships, we first estimated the historical steel stocks and flows respect to global ships from 1980 to 2019, and further projected the amount of steel scraps from shipbreaking by 2050. The steel stocks of ships increased by 2.6 times from 208.4 Mt in 1980 to 542.9 Mt in 2019. The top 2 regional contributors, Asia and Latin America & the Caribbean, were together responsible for about half of the total increase. A transition from oil tankers to container ships and bulk carriers reduced the in-use steel stock due to the lower steel intensity of the latter. The rapid increase of ship stocks after year 1980 led to significant increase of steel scrap in the 2010 s, reaching 10.1 Mt/year in 2019. Our projections showed that the steel from scrapped ships worldwide will increase by around 4-fold to 40.4–47.3 Mt/year by 2050, which imposed a great challenge on coordination of recycling ship-related steel and require long-term planning on ship recycling facility development. By identifying the stocks and flows of ships and related steel, this study provides insights for the steel waste and recycling management of end-of-life ships worldwide. 相似文献
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