Harmonic generation past a submerged porous step     

I. J. Losada  M. D. Patterson  M. A. Losada 《Coastal Engineering》1997,31(1-4)

Experiments were conducted in a wave flume to study the differences between harmonic evolution of monochromatic waves as they propagate over a submerged impermeable or porous step under non-breaking conditions. Results are used as a preliminary analysis to establish some engineering design criteria on harmonic generation on submerged porous structures. The root-mean-squared wave height evolution is also studied and compared to linear models as a first approximation. It is shown that porous structure increases the effective relative depth and decreases the relative wave height, resulting in a lower Ursell number and a lower chance to generate harmonics. The effective water depth over a step as defined in the paper, provides information to evaluate the potential harmonic generation.  相似文献   

海冰业务化预报基础研究进展     

李春花  刘钦政  白珊  张启文  李宝辉  刘煜  王旭 《海洋预报》2005,22(Z1):50-55

本文概述了我国近年来在海冰预报基础研究方面的工作进展情况,着重介绍了在我国海冰的气候成因、海冰分布特征和变化规律等方面的研究成果.  相似文献   

Impact of Sea-Land Interaction on Evolution of Taihu Lake     

孙金华  陆桂华 《中国海洋工程》2006,20(1):173-178

1 .IntroductionFor Lakes near the middle andlower reaches of the Yangtze River ,theformationof lake basinsisgreatly affected by geological structures ,andthe interaction betweenrivers and seas .The Taihu Lakeis locatedinthelow-lying plain nearthe east coa…  相似文献   

Nonlinear Static Finite Element Stress Analysis of Pipe-in-Pipe Risers   总被引：4，自引：1，他引：4  

周宏杰  闫澍旺崔溦 《中国海洋工程》2005,19(1):155-166

Owing to the complexity of the pipe-in-pipe (PIP) riser system in structure, load and restraint, many problems arise in the structural analysis of the system. This paper presents a new method for nonlinear static finite element stress analysis of the PIP riser system. The finite element (FE) model of the PIP riser system is built via software AutoPIPE 6.1. According to the specialties of a variety of components in the PIP riser system, different elements are used so as to model the system accurately. Allowing for the complication in modeling the effects of seabed restraint, a technique based on the bilinear spring concept is developed to calculate the soil properties. Then, based on a pipeline project, the entire procedure of stress analysis is discussed in detail, including creation of an FE model, processing of input data and analysis of results. A wide range of loading schemes is investigated to ascertain that the stresses remain within the acceptable range of the pipe material strength. Finally, the effects of the location of flanges, the thermal expansion of submarine pipelines and the seabed restraint on stress distribution in the riser and expansion loop are studied, which are valuable for pipeline designers.  相似文献   

自升式平台冰激动力响应分析     

张剑波 《海洋科学进展》2007,25(1):85-90

应用ANSYS软件建立了平台和冰相互作用的有限元模型,构建了自升式平台的冰激振动模型,并计算基于2种冰力模型的自升式平台的动力响应。此动力分析方法具有建模方便和计算精度高的特点。以某自升式平台为例,计算了冰和平台结构相互作用的耦合效应,为自升式平台冰激振动安全评估提供了参考依据。  相似文献   

融冰季节北极破碎冰区热通量的初步研究   总被引：5，自引：1，他引：5  

史久新  赵进平  矫玉田 《海洋科学进展》2002,20(3):35-43

利用航空遥感数字影像的解析结果和实测气象，海洋和海冰资料，定量研究了夏季融冰期北极破碎冰区的热通量，计算了海洋对大气的热贡献，结果表明，在北极夏季海冰融化时，短波辐射远远大于感热和潜热通量，是表面热通量的决定因素，海洋对大气的热贡献主要由长波辐射决定，在观测期间，海洋对大气的热贡献为38～104Wm^-2，这部分热量的大小与海冰的密集度有关，当海冰密集度小于0.8时，海洋对大气的热贡献随海冰密度度的增大而减小，而当海冰密集度超过0.8以后，该热通量将随海冰密集度的增大而增大。  相似文献   

海冰板的环形屈曲的压缩破坏   总被引：2，自引：0，他引：2  

唐立强  陈会军等 《海洋工程》2001,19(4):29-33

在轴对称条件下，给出海冰板的环向屈曲面临载荷，从细观力学的观点分析了微裂纹开裂的条件，扩展方向并给出绕海洋平台柱腿冰的损伤区的尺度。所给出的临界半径是一个与冰材料力学特征，冰的微结构参数一海洋平台柱腿半径相关的特征参数。对现场所观察和测量的结构给出了解释和定量分析。  相似文献   

Internal wave eigenmodes and their weak nonlinear resonant interaction in a nonlinearly stratified fluid—A preliminary theoretical and experimental study     

Wang Yiming  Xu Zhaoting 《中国海洋湖沼学报》1992,10(1):44-56

A preliminary theoretical and experimental study was conducted on internal wave modes and their weak nonlinear resonant interaction in a nonlinearly stratified fluid. An asymptotical solution of the modes and a dispersion relation of internal waves in a stratified fluid with density profile similar to that in our experiment were obtained theoretically. The resonant-interaction mechanism to 2nd order approximation is also discussed. The resonant interaction of the 3rd and 4th mode internal waves excited by the unstable 1st mode wave is analyzed on the basis of data obtained by conductivity probes. The resonant-interaction condition, i.e., ,k ₁+k ₃+k ₄=0, is examined. It is shown that the resonant instability increases with pycnocline thickness and wave maker driving frequency. This work is supported by the National Natural Science Foundation of China.  相似文献   

青海共和盆地多石在沟河道沙丘现代风水交互过程   总被引：2，自引：0，他引：2       下载免费PDF全文

马玉凤  严平  宋阳  杜建会  朱孟郡  丁连刚 《第四纪研究》2008,28(4):695-701

选择青海共和盆地多石在沟河道中6道新月形沙丘链作为研究对象,采用Trimble4700DGPS与常规测量手段,结合野外风沙观测与自动气象站数据,初步观测分析了2006年多石在沟河道沙丘在不同季节的形态变化过程,计算出2006年风季前比雨季后多石在沟河道沙丘体积减小了548.3m³,风积量为2351m³,流水的蚀平量为2899m³,2006年风水两相营力对河道沙丘的侵蚀贡献率约为45%∶55%,流水的搬运作用强于风力的堆积作用。但从较长的时间尺度来看,研究区的风力侵蚀作用强于流水侵蚀作用,河道沙丘不断增大。多石在沟河道沙丘是一个典型的风水交互作用系统,河道成为风力与流水交互作用的"中转站",在风水的交替作用下,沉积物由风积环境进入流水环境中。  相似文献   

区域成矿与壳幔作用初探     

丁玉进  何胜飞  李社宏  刘战庆 《华南地质与矿产》2008,(4):14-21

区域成矿研究从简单到复杂,从地表到地壳深部,现在已经向众多学科,纵深领域渗透。壳幔作用是现代地球动力学研究的一个关注点。本文对壳幔动力作用与区域成矿关系进行探讨,分别讨论了俯冲、底侵、拆沉和地幔柱对区域成矿作用的影响和作用。初步建立了深部动力作用与区域成矿之间的关系,为研究区域成矿的深部机理和规律提供依据。  相似文献