Redundancy Measure and Its Application to the Design and Maintenance of Marine Structures     

Yu Qing Xiao Xi Lecturer 《中国海洋工程》1997,(2)

This paper is a survey of the state-of-the-art knowledge in structural redundancy measure andits application.The existing deterministic and probabilistic measures of structural redundancy are summa-rized.Emphasis is given to the discussion of their advantages and limitations.The application of damagetolerance concept in the design and maintenance of marine structures is also reviewed.Some most criticalproblems in structural redundancy are proposed for future research.  相似文献   

沿岸海区冬季垂直环流及其温盐结构的数值研究　Ⅰ.环流的基本特征     

刘兴泉 《海洋与湖沼》1997,28(6):632-639

为了揭示沿岸海区冬季垂直环流及其温盐结构的分布特征和变化规律，利用三维斜压流体动力学模型，对具有岸界坡度变化、河流入海、海湾、岛屿和海槽的理想海区冬季的垂直环流及其温盐结构进行了数值模拟。其环流的数值结果表明，冬季沿岸海区的垂直环流普遍呈逆时针流动。在近表层为向岸流，沿岸为下降流，近表层以下为离岸流；近表层以下的离岸流在外海有明显的上升趋势；沿岸下降流自表层至底层逐渐由强变弱；就整个海区而言，随着自南往北海区水深的逐渐变浅和岸界地形坡度的由大变小，其沿岸下降流则由强变弱。  相似文献   

A new hypothesis about the surface circulation in the eastern basin of the mediterranean sea   总被引：3，自引：1，他引：3  

Najwa Hamad  Claude Millot  Isabelle Taupier-Letage 《Progress in Oceanography》2005,66(2-4):287

In time, the circulation of the Atlantic Water (AW) in the eastern basin of the Mediterranean Sea has been described differently, according to two major representations. The historical one, which began with the scheme from Nielsen in 1912 and has been refined up to the 1980s, favours a counterclockwise circulation in the whole basin, with AW flowing in its southern part as a broad flow off Libya and Egypt (from the Ionian to the Levantine subbasins), then continuing along Middle-East and Turkey before flowing back westwards. The more recent one, issued in the 1990s, favours a clockwise circulation in the northern part of the Ionian continuing offshore across the basin from the Cretan to the central part of the Levantine as the so-called “Mid-Mediterranean Jet”. This jet is depicted then as splitting both clockwise in the southeastern part of the basin and counterclockwise off Turkey (where this representation agrees with the former). Because the recent representation cannot be considered as a refinement of the historical ones, we have been interested in understanding why a given data set available to everybody is interpreted in such different ways.In the Algerian subbasin, the combined use of satellite infrared images and a significant amount of in situ data sets (hydrology and both Eulerian and Lagrangian current measurements) allowed us to solve a similar controversy. Therefore, we examined the circulation features in the eastern basin, undertaking the detailed analysis of 1000 daily and weekly composite images spanning the period 1996–2000, and of monthly composite images available since 1985. Whenever in situ observations were available, we have confronted them with the satellite thermal signatures and have shown that both are consistent. This paper focuses on the overall (basin scale) results while the detailed ones are published in an other paper. The new scheme we propose is basically a refined version of the historical ones: the circulation of AW is counterclockwise in the whole eastern basin but it is more constrained alongslope than previously thought, and the broadening historically schematised appears to be due to intense mesoscale eddies mainly generated by the instability of this circulation.  相似文献   

Numerical Study of the Upper-Layer Circulation in the South China Sea   总被引：7，自引：0，他引：7  

Ching-Sheng Chern  Joe Wang 《Journal of Oceanography》2003,59(1):11-24

Upper-layer circulation in the South China Sea has been investigated using a three-dimensional primitive equation eddy-resolving model. The model domain covers the region from 99° to 122°E and from 3° to 23°N. The model is forced by the monthly averaged European Centre for Medium-Range Weather Forecasts (ECMWF) model winds and the climatological monthly sea surface temperature data from National Oceanographic Data Center (NODC). Inflow and outflow through the Taiwan Strait and the Sunda shelf are prescribed monthly from the Wyrtki estimates. Inflow of the Kuroshio branch current in the Luzon Strait is assumed to have a constant volume transport of 12 Sv (1 Sv = 10⁶ m³/s), and the outflow from the open boundary to the east of Taiwan is adjusted to ensure the net volume transport through all open boundaries is zero at any instant. The model reveals that a cyclonic circulation exists all year round in the northern South China Sea. During the winter time this cyclonic eddy is located off the northwest of Luzon, coinciding with the region of positive wind stress curl in this season. This cyclonic eddy moves northward in spring due to the weakening of the northeast winds. The cyclonic circulation becomes weak and stays in the continental slope region in the northern South China Sea in the summer period. The southwest wind can raise the water level along the west coast of Luzon, but there is no anticyclonic circulation in the northern South China Sea. After the onset of the northeast monsoon winds in fall, the cyclonic eddy moves back to the region off the west coast of Luzon. In the southern South China Sea and off the Vietnam coast, the model predicts a similar flow structure as in the previous related studies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Long-term hydrographic variation in the Skagerrak based on the section Torungen-Hirtshals     

Danielssen  Didrik S.; Svendsen  Einar; Ostrowski  Marek 《ICES Journal of Marine Science》1996,53(6):917-925

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等密度面P矢量方法在南海环流诊断研究中的应用   总被引：1，自引：0，他引：1  

王桂华  许建平 《海洋学报》2002,24(1):124-128

海流的直接测量困难而又昂贵,而采用一些数学模式间接获取流场信息也有其局限性,比如初始场、边界条件和黏性参数的确定存在较大的人为性和不确定性等问题.然而,随着海上现场观测资料的增多,近年来利用温盐资料诊断环流的研究工作也越来越多,例如采用β螺旋方法[1]、P矢量方法[2]和改进逆模式方法[3]等等;这些诊断研究成果,在一定程度上弥补了海洋环流研究中,由于海流观测资料不足而带来的缺陷.在众多诊断环流计算方法中,近年来用得较多的是P矢量方法[2,4,5],1).  相似文献   

最近6.5～2.2 Ma黄土高原粉尘通量变化及其指示的东亚冬季风演化和亚洲干旱化   总被引：13，自引：0，他引：13  

曹军骥  张小曳  安芷生  郑洪波 《海洋地质与第四纪地质》2003,23(3):97-101

黄土高原红粘土沉积与北太平洋885/886孔深海沉积记录的亚洲粉尘沉积通量对比显示,海陆风尘记录万年尺度的变化趋势一致,指示了6．5Ma以来亚洲内陆干旱化和冬季风环流变化的历史：6．5MaRP粉尘源区出现一定程度的干旱化,粉尘通量增加,为红粘土的形成提供了物质基础;5．2～3．6MaBP源区气候较为湿润,冬季风环流偏弱,导致粉尘通量大幅下降;3．6～2．6MaBP。由于青藏高原加速隆升,导致源区气候迅速干旱,冬季风环流发展,粉尘通量急剧增加。但海陆粉尘通量变化也存在差异,显示出区域及半球或全球尺度上粉尘输送方式的不同。  相似文献   

Hydrography of the East Shetland Basin in relation to decadal North Sea variability   总被引：2，自引：0，他引：2  

Turrell  W. R.; Slesser  G.; Payne  R.; Adams  R. D.; Gillibrand  P. A. 《ICES Journal of Marine Science》1996,53(6):899-916

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Study on short-range numerical forecasting of ocean current in the East China Sea Ⅱ. Three-dimensional diagnostic model and its application in the Bohai Sea     

Zhao Jinping  Shi Maochong 《海洋学报(英文版)》1994,13(2):173-188

Ｓｔｕｄｙｏｎｓｈｏｒｔ－ｒａｎｇｅｎｕｍｅｒｉｃａｌｆｏｒｅｃａｓｔｉｎｇｏｆｏｃｅａｎｃｕｒｒｅｎｔｉｎｔｈｅＥａｓｔＣｈｉｎａＳｅａ—ＩＩ．Ｔｈｒｅｅ－ｄｉｍｅｎｓｉｏｎａｌｄｉａｇｎｏｓｔｉｃｍｏｄｅｌａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｉｎｔ...  相似文献   

Path Transition of the Kuroshio Due to Mesoscale Eddies: A Two-Layer, Wind-Driven Experiment   总被引：1，自引：0，他引：1  

Kazunori Akitomo  Masao Kurogi 《Journal of Oceanography》2001,57(6):735-741

We have executed numerical experiments using a two-layer, wind-driven ocean model with simplified coastal geometry and bottom topography to investigate the possibility of the Kuroshio path transition due to mesoscale eddies. A straight path easily changes into a meandering path due to the eddy action. For this transition, an anticyclonic eddy is preferable to a cyclonic one when imposed in the beginning region of the Kuroshio (east of Taiwan). When imposed southeast of Kyushu, on the other hand, a cyclonic eddy is more effective than an anticyclonic one. The reverse transition, from a meandering to a straight path, did not occur at all in this experiment. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献