A comparison of several wave spectra for the random wave diffraction by a semi-infinite breakwater     

Hong Sik Lee  Sung Duk Kim 《Ocean Engineering》2006,33(14-15):1954-1971

A comparison of the diffraction of multidirectional random waves using several selected wave spectrum models is presented in this paper. Six wave spectrum models, Bretschneider, Pierson–Moskowitz, ISSC, ITTC, Mitsuyasu, and JONSWAP spectrum, are considered. A discrete form for each of the given spectrum models is used to specify the incident wave conditions. Analytical solutions based on both the Fresnel integrals and polynomial approximations of the Fresnel integrals and numerical solutions of a boundary integral approach have been used to obtain the two-dimensional wave diffraction by a semi-infinite breakwater at uniform water depth. The diffraction of random waves is based on the cumulative superposition of linear diffraction solution. The results of predicted random wave diffraction for each of the given spectrum models are compared with those of the published physical model presented by Briggs et al. [1995. Wave diffraction around breakwater. Journal of Waterway, Port, Coastal and Ocean Engineering—ASCE 121(1), 23–35]. Reasonable agreement is obtained in all cases. The effect of the directional spreading function is also examined from the results of the random wave diffraction. Based on these comparisons, the present model for the analysis of various wave spectra is found to be an accurate and efficient tool for predicting the random wave field around a semi-infinite breakwater or inside a harbor of arbitrary geometry in practical applications.  相似文献   

利用消去刚度法进行剪切型系统物理参数识别     

王树青  李华军 《中国海洋大学学报(自然科学版)》2004,34(6):1085-1089

提出了 1种能够比较准确地识别剪切型体系的结构参数 (各层质量和层间刚度 )的方法———消去刚度法。该方法从剪切型结构体系的特征值问题出发 ,利用剪切型结构系统质量矩阵和刚度矩阵的特殊形式 ,通过消去各层的刚度系数 ,得到了结构系统的各层质量比表达式。在结构总质量已知的情况下 ,仅利用系统的任意两阶模态信息就可以确定出各层质量 ,并进而计算出层间刚度 ,实现了结构物理参数的递推识别。数值模拟结果表明 ,该方法识别精度较高 ,便于工程应用 ,可以用于类似结构体系的物理参数的初步估计。  相似文献   

Observations and Estimations of Directional Spectrum of Sea Waves   总被引：1，自引：1，他引：1  

Liu Shuxue Yu Yuxiu Assistant Researcher  State Key Laboratory of Coastal  Offshore Engineering  Dalian University of Technology 《中国海洋工程》1995,(1)

The directional spectrum is one of the basic characteristics of sea waves. The observations of directional spectrum of sea waves were successfully conducted at platform Bohai 8 during 1991 and 1992 using a wave gage array for the first time in China. Based on the field data, the directional spectrum which depends on the wave growth is given in this paper. Before observations, the effects of the type of gage array, the distance between the gages and the platform itself on the measured results and the precision of some methods for estimating the directional spectrum were investigated and compared with the methods of numerical simulations and model tests of multi-direcitonal irregular waves. This ensures the quality of the observations and estimations of the directional spectrum.  相似文献   

耗氧速率(OUR)测量方法的实验研究   总被引：4，自引：0，他引：4  

李冰  孙英兰  李玉瑛 《中国海洋大学学报(自然科学版)》2006,36(3):456-460

目前多采用分批实验法和呼吸测量仪测量耗氧速率,而耗氧速率的测量对于研究活性污泥数学模型中的动力学参数及废水特性鉴定具有重要意义。本文根据OUR测量方法的基本原理设计了1种简易的OUR测量装置,为检验测量装置的有效性,设计了相关实验进行验证。在内源呼吸实验中,测定了所用活性污泥的内源呼吸速率是5.1mgO2/L·h,污泥的衰减系数是0.0137h-1,比文献值略高。基质降解实验对人工配水(葡萄糖和淀粉)的耗氧速率进行了测定,实验结果显示有3个显著不同的耗氧速率,分别为35mg/L·h,13mg/L·h,6mg/L·h,它们各代表葡萄糖降解、淀粉降解和内源呼吸的速率。内源呼吸速率高于前1个实验是由于基质降解过程中污泥量增加所致。并计算出异养菌产率系数Kd为0.63mgVSS/mgCOD,Kd略低于文献值。实验结果证明,该装置能很好的实现测量目的。  相似文献   

利用地下水水位资料推求水文地质参数     

李巍然  姜效典 《中国海洋大学学报(自然科学版)》1993,(Z1)

依据模糊集合理论,提出了反求水文地质参数的一种新方法,即用模糊模式识别评价计算水位与观测水位的拟合程度,依模糊ISODATA聚类法的原理建立目标函数,以相应的聚类中心作为要求的水文地质参数。  相似文献   

黄海海域陆相中生界油气远景   总被引：8，自引：1，他引：8  

李刚  陈建文  肖国林  温珍河  戴春山  龚建明  闫桂京 《海洋地质前沿》2003,19(8):7-11

黄海海域油气勘探已40余载，尚未实现油气突破，其找油前景引起石油地质学家的极大关注。根据前人的认识和最新研究成果，结合邻区油气地化资料，探讨了黄海海域中生界地层生、储、盖特征，特别是白垩系，它分布广，厚度大，烃源岩达到较好生油岩标准，并且生、储、盖组合理想，中生界是该区下部油气勘探首选目标。  相似文献   

海岸工程中海浪数值模拟和环境参数选取的进展     

黄培基 《海岸工程》1995,14(4):1-4

主要介绍了我国近的来在海岸工程设计，建设中有关海浪数值模拟及环境参数选取方面的研究进展。  相似文献   

Wave runup on a concentric twin perforated circular cylinder     

K. Vijayalakshmi  S. Neelamani  R. Sundaravadivelu  K. Murali 《Ocean Engineering》2007,34(2):327-336

The regular wave interaction with a twin concentric porous circular cylinder system consisting of an inner impermeable cylinder and an outer perforated cylinder was studied through physical model and numerical model studies. The experiments were carried out on the twin concentric cylinder model in a wave flume to study the wave runup and rundown at the leading and trailing edges of the perforated cylinder. It was found that the maximum wave runup on the perforated cylinder is almost same as the incident wave height. The experimental results were used to develop the predictive formulae for the wave runup and rundown on the perforated cylinder, which can be easily used for design applications. The wave runup profiles around the perforated cylinder for different values of ka and porosities were studied numerically using Green's Identity Method. The results of the numerical study are presented and compared with the experimental measurements.  相似文献   

SAS测量水体表观光学参数的方法     

李铜基  陈清莲 《海洋技术学报》2003,22(1):10-13,57

SeaWiFS航空模拟器（SAS）是专门为在水面之上测量水体表观光学参数的现场设备。文章在介绍SAS现场测量以及数据处理基本方法的基础上，分析了2002年黄海试验SAS的应用效果，并与剖面法测量数据进行了比对。  相似文献   

中国海区区域地质编图中重磁图的编制方法     

张训华 《海洋地质与第四纪地质》1994,14(4):95-100

本文简要介绍了局控项目《中国海区１∶５０万区域地质编图（大连幅）》重力异常图、磁力异常图的编制过程，给出了一种以计算机为手段、实现编图自动化的新方法，并分析了该方法与以往编图方法的不同和优点，以国际分幅在中国海区开展区域地质编图尚属首次，在既无海区地质调查规范，又无海区地质调查编图规范的情况下，这一工作无异具有开创性。从理论上系统总结出一套切实可行的编图方法，对于编制中国海区区域地质调查编图规范以  相似文献