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The scattering problem involving water waves by small undulation on the porous ocean-bed in a two-layer fluid,is investigated within the framework of the two-dimensional linear water wave theory where the upper layer is covered by a thin uniform sheet of ice modeled as a thin elastic plate.In such a two-layer fluid there exist waves with two different modes,one with a lower wave number propagate along the ice-cover whilst those with a higher wave number propagate along the interface.An incident wave of a particular wave number gets reflected and transmitted over the bottom undulation into waves of both modes.Perturbation analysis in conjunction with the Fourier transform technique is used to derive the first-order corrections of reflection and transmission coefficients for both the modes due to incident waves of two different modes.One special type of bottom topography is considered as an example to evaluate the related coefficients in detail.These coefficients are depicted in graphical forms to demonstrate the transformation of wave energy between the two modes and also to illustrate the effects of the ice sheet and the porosity of the undulating bed. 相似文献
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学习贯彻十七大精神,对于动员拿党全国各族人民,存以胡锦涛同忠为总书记的党中央坚强领导下,高举中国特色社会主义伟大旗帜,奋力夺取全面建没小埭社会新胜利、圩创中国特色礼会主义事业新局而,具有重大现实意义和深远历史意义。长汀航道各级党组织要把组织学习和贯彻落实十七大精神作为当前和今后一个时期的首要政治任务,迅速把干部职工的思想和行动统一到全会精神上来, 相似文献
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0引言近年来全球集装箱运量的年增长率基本维持在10%以上,据初步统计2007年全球集装箱运量达1.3亿TEU,港口吞吐量达4.7亿TEU。随着集装箱制造、装卸工艺的改进,适箱货物的范围也在不断扩大。20世纪90年代,美国就开始采用集装箱运 相似文献
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<正>众所周知,三一重工股份有限公司是一家享有盛誉的上市公司,曾连续4年上榜中国最具价值品牌,是工程机械行业内的标志性企业之一。作为中国最具科研实力的工程机械制造商,三一重工拥有国家级技术中心、博士后工作站,并承接有国家863课题,取得专利400多项。三一重 相似文献
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美国海岸警备队港口长官(COTP)或口岸当局(OCMI)对存在缺陷的船舶,根据缺陷的严重性,决定对这些船舶采取控制行动来保证船舶、港口和环境的安全,至于控制的程度、范围以及当局的执行力则和这些缺陷的本性一致. 相似文献
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Global strength is a significant item for floatingproduction storage and offloading (FPSO) design, and steel weightplays an important role in the building costs of FPSO. It is the maintask to consider and combine these two aspects by optimizing hulldimensions. There are many optional methods for the globalstrength analysis. A common method is to use the ABS FPSOEagle software to analyze the global strength including the rulecheck and direct strength analysis. And the same method can beadopted for the FPSO hull optimization by changing the depth.After calculation and optimization, the results are compared andanalyzed. The results can be used as a reference for the futuredesign or quotation purpose. 相似文献
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由丹丹;孙丽萍;曲治国;王涛 《船舶与海洋工程学报》2013,12(4):459-462
For a large floating vessel in waves,radiation damping is not an accurate prediction of the degree of roll unlike other degrees of freedom motion.Therefore,to get the knowledge of roll motion performance of deepwater pipelay crane vessels and to keep the vessel working safety,the paper presents the relationship between a series of dimensionless roll damping coefficients and the roll response amplitude operator(RAO).By using two kinds of empirical data,the roll damping is estimated in the calculation flow.After getting the roll damping coefficient from the model test,a prediction of roll motion in regular waves is evaluated.According to the wave condition in the working region,short term statistics of roll motion are presented under different wave parameters.Moreover,the relationship between the maximal roll response level to peak spectral wave period and the roll damping coefficient is investigated.Results may provide some reference to design and improve this kind of vessel. 相似文献
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Radar cross section(RCS) is the measurement of the reflective strength of a target.Reducing the RCS of a naval ship enables its late detection,which is useful for capitalizing on elements of surprise and initiative.Thus,the RCS of a naval ship has become a very important design factor for achieving surprise,initiative,and survivability.Consequently,accurate RCS determination and RCS reduction are of extreme importance for a naval ship.The purpose of this paper is to provide an understanding of the theoretical background and engineering approach to deal with RCS prediction and reduction for naval ships.The importance of RCS,radar fundamentals,RCS basics,RCS prediction methods,and RCS reduction methods for naval ships is also discussed. 相似文献
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研究了舰艇外形雷达隐身优化设计问题。介绍了舰艇外形雷达隐身防护常用措施和进行雷达隐身性能评估的数值方法,提出外形隐身优化的多层次设计优化模型理论及相关数学表达式。以某型船为例,进行外形隐身截面尺寸优化,将全船隐身设计与常规设计相比较,验证外形隐身设计优化理论的正确性和优越性。 相似文献
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30000DWT多用途集装箱船的研制 总被引:1,自引:1,他引:0
该船是上海船厂与德国著名船舶设计师Mr.Albert联合设计并由上海船厂制造的多用途集装箱船,其特点是载重量大,集装箱数多、用途广、航速快、油耗低、自动化程度高、悬挂德旗、符合水下检验IW的要求。本文扼要介绍了在设计和建造中所采取的主要技术措施。 相似文献
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考虑雷达隐身性能要求的舰艇外形截面设计 总被引:2,自引:0,他引:2
舰艇雷达隐身性能设计是舰艇生命力设计的重要内容,直接影响其作战效果。舰艇雷达隐身最为有效的途径是进行外形隐身设计,而舰艇主要截面在雷达波各入射角下的雷达散射截面的大小将决定舰艇整体隐身性能的优劣。本文在介绍雷达隐身性能分析常用数值方法的基础上,研究了通过对不同截面外形的雷达散射截面计算,进而得到隐身性能较好的截面外形的设计方法。文中还进行了全船隐身设计和分析,并与常规设计相比较,验证了外形截面隐身设计的优越性。 相似文献