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891.
Based on the Nansha Islands' closed atoll conception-remote sensing system in Part Ⅰ,through the solution of the information function value and isostatic value of closed and quasi-closed atoll, and by using topological analysis on growth form and the composite remote sensing quantization date as the calculating coefficients, the feature vector system and its mathematical model of two kinds of atoll are built, and the multivariate analysis is made with some examples. 相似文献
892.
Chen Tieyun Zhang Huiyuan Professor Shanghai Jiao Tong University Shanghai
Doctor of Engineering Shenzhen Shipbuilding Trading Co. LTD. 《中国海洋工程》1993,(1)
- Stress concentration analysis of multiplanar tubular DT joints plays an important role in the fatigue design of offshore platforms. A semi-analytic method for stress analysis under the condition of any loads is briefly introduced in the paper. Nineteen multiplanar tubular DT joints with one of two braces of the same dimension subjected to axial loads and out- of- plane bending moments are computed for parametric stress analysis by using the present method. The influence of geometrical parameters on the stresses of multiplanar tubular DT joints is discussed and compared with corresponding uniplanar T joints. The regression formulae for the stress at hot spot of multiplanar DT joints are found by modification of SCF of corresponding uniplanar T joints. The parametric formulae for the maximum stress by superposition. Finally, the influences of stiffening effect and load-interaction effect on the maximum stress of DT joints are discussed. 相似文献
893.
894.
复合加载条件下吸力式沉箱基础承载特性数值分析 总被引:2,自引:0,他引:2
吸力式沉箱基础的承载特性是海洋工程结构设施建造与设计中的一个关键问题。这种新型的深水海洋基础型式,通常承受竖向上拔荷载与水平荷载的共同作用,其工作性能与设计理论远远不能满足工程实践的需要。本文采用有限元分析方法对吸力式沉箱基础的极限承载特性进行数值计算。以大型通用有限元分析软件ABAQUS为平台,通过二次开发,数值实现了Swipe试验加载方法和固定位移比分析方法,针对不同的沉箱长径比、土的强度折减系数,探讨了沉箱基础在垂直上拔荷载和水平荷载单调联合作用下的极限承载力,通过对不同荷载组合的数值计算构造了复合加载条件下沉箱基础破坏包络面。 相似文献
895.
对7株赤潮原甲藻28S rDNA 5'端部分序列进行扩增、克隆和序列测定,并从GeneBank上获取14个原甲藻28S rDNA序列,用NJ法和ME法构建了原甲藻属的系统树,并对序列进行分析.结果表明,7株原甲藻28S rDNA扩增序列长度为950~958 bp,通过NJ法和ME法构建的系统树完全一致.大部分分离自不同海域的同种原甲藻的序列高度保守,而不同种间在序列高变区却有较大的差异.但来自南海海域的海洋原甲藻(Prorocentrum micans)与分离自其他海域的株系序列差异较大,甚至超出了有些种间的差异.由28S rDNA高变区获得的序列,有望成为浮游植物特异性分子探针设计的良好靶区域. 相似文献
896.
897.
Empirical orthogonal functions (EOFs) or principal components were used to extract the significant modes of shoreline variability from several data sets collected at three very different locations. Although EOFs have proven to be a valuable tool in the analysis of nearshore data, most applications have focused on the ability of the technique to describe cross-shore or profile variability. Here however, EOFs were used to help identify the dominant modes of longshore shoreline variability at Duck, North Carolina, the Gold Coast, Australia, and at several locations within the Columbia River Littoral Cell in the U.S. Pacific Northwest. In part one of this analysis, characteristic patterns of shoreline variability identified by the EOF analysis are described in detail. At each site, the dominant modes consisting of the first four eigenfunctions were found to describe nearly 95% of the total shoreline variability. At both Duck and the Gold Coast, several interesting longshore periodic features suggestive of sand waves were identified, while boundary effects related to natural headlands and navigational structures/entrances dominated the Pacific Northwest data sets. 相似文献
898.
天津近海潮汐特征分析 总被引:1,自引:0,他引:1
对塘沽海洋环境监测站从1950年-2008年,59年的潮汐资料进行调和分析,分析了其分潮调和常数的变化曲线,并利用FFT谱分析方法对其调和常数的变化周期和原因进行了分析;之后应用FFT谱分析方法对去除天文潮后的余水位进行分解,分析了近50多年来年平均余水位的多层次周期分布,进而利用最小二乘法进行线性分析,分析了天津近海... 相似文献
899.
900.
This paper aims to validate a numerical seakeeping code based on a 3D Rankine panel method by comparing its results with experimental data. Particularly, the motion response and hull-girder loads on a real modern ship, a 6500 TEU containership, are considered in this validation study. The method of solution is a 3D Rankine panel method which adopts B-spline basis function in the time domain. The numerical code is based on the weakly nonlinear scheme which considers nonlinear Froude-Krylov and restoring forces. The main focus of this study is given to investigate the nonlinear characteristics of wave-induced loads, and to validate this present scheme for industrial use in the range of low Froude number. The comparisons show that the nonlinear motions and hull-girder loads, computed by the present numerical code, have good overall agreements with experimental results. It is found that, for the better accuracy of computational results, particularly at extreme waves in oblique seas, the careful treatment of soft-spring (or compatible) system is recommended to the control of non-restoring motions such as surge, sway, and yaw. 相似文献