Wave run-up and overtopping on smooth and rough slopes of coastal structures     

N. J. Shankar  M. P. R. Jayaratne 《Ocean Engineering》2003,30(2):221-238

A series of hydraulic model tests has been carried out in a glass wave flume to investigate the influences of wave height, wave period, wave steepness, surf similarity parameter, roughness, layer thickness and porosity on wave run-up and overtopping of 1:2 sloped impermeable and permeable breakwaters fronted by a 1:10 gentle, smooth beach slope. The analysis of results involves the correlation between the overtopping energy transfer with the relative wall height and the relationship between wave run-up and overtopping rate. Further, measured wave run-up and overtopping rates are compared with the results given in the Shore Protection Manual (1984), Automated Coastal Engineering System (1992)and results of other investigators.  相似文献   

A fuzzy distinguishability on species composition similarities of pelagic fishes in different years in the southern Taiwan Strait     

Zhang Chengmao  Fang Shuimei  Yang Shengyun 《海洋学报(英文版)》2001,20(4):575-583

I\rnooUcrIoxThe drpdric fish species cor-npositlon is an imPOrtant element 1n the study of fish ecologyand plays an important guiding role ln fishery preduction and roouLrces rnanagement. Lin(l988) and Zhang (1994 and l995) have studied the simi1drities of mpulation COtwsition ofame s1ngle species of different yea-rs including hairtail Trichuras haumee and yellDw cndertwinena cmi. But no rePOrt is available on the discridrination of the sidrildrities amongmuLlt1ple sPecies composition of…  相似文献   

台风预报系统     

徐勤爱  张德宇 《海洋湖沼通报》1994,(2):105-112

本文介绍的是一项在微机上实现的台风预报专家系统。该系统可进行台风气候查询、台风路径检索、台风特例查询，并能利用相似加权法制作出１２－７２小时台风路径和中心强度预报，对异常路径台风也可提供一定的诊断预报判据。本系统已在军内外一些气象业务单位得到应用，实践证明它是一种简便有效的台风预报工具。  相似文献   

基于本体的地理信息服务查询组件设计   总被引：1，自引：0，他引：1  

程钢  杜清运  蔡忠亮 《测绘信息与工程》2008,33(2):31-33

介绍了一种基于本体的服务发现组件设计方法,将基于本体的元数据和基于本体的查询结合起来,提高了基于OGC标准的网络地理服务发现的查询效率和准确性.  相似文献   

基于语义的地理信息分类体系对比分析     

张雪英  闾国年 《遥感学报》2008,12(1):9-14

地理信息分类体系之间的语义不一致性,被认为是影响地理信息系统实现在语义层次上信息共享的最大障碍.首先,本文在阐述中国地理信息分类体系之间参照模式的基础上,提出了一种基于语义的地理信息分类体系对比分析方法.其次,对中国现行的几种地理信息标准分类体系进行了详细的对比分析.最后,为中国地理信息分类体系的编制和修订提出了一些建议.  相似文献   

多尺度空间线状实体形状相似关系的表达与度量   总被引：6，自引：2，他引：4  

张永华  程耀东  闫浩文  刘纪平 《测绘科学》2008,33(6):83-85

本文对空间数据多尺度表达中线状实体综合前后的形状相似性进行了描述、分析和研究。通过调查统计,得出了衡量线状实体形状相似程度的两个重要参量SIMⅠ、SIMⅡ,基于这两个参量给出了空间线状实体形状相似性的定义以及在不同尺度下线状实体形状相似性的度量方法,并用实例进行验证。为空间数据多尺度表达时线状实体的形状表达提供了一种分析和评价手段。  相似文献   

基于实例的GIS数据库模式匹配方法     

王育红  陈军 《武汉大学学报(信息科学版)》2008,33(1):46-50

针对空间数据库的特点,提出了一种改进的基于实例的层次式模式匹配方法,并解决了实体对应关系的自动建立、要素类相似性计算、属性相似性计算等问题.最后,通过实验验证了该方法的有效性.  相似文献   

Seaweed floristic studies along tsunami affected Indian coasts: A litmus test scenario after 26th December 2004     

Vaibhav A Mantri 《Journal of Earth System Science》2006,115(3):371-378

On 26th December 2004, the world witnessed the devastating power of tsunami, affecting many countries, bordering the Indian Ocean region. This has caused significant changes in the shallow and intertidal regions of the Indian coast, especially the Andaman and Nicobar Islands, Tamil Nadu, Kerala and Pondicherry. The baseline data on biomass availability and distribution of benthic intertidal seaweed species were collected immediately after this catastrophic event by spot surveying 11 selected localities of the above-mentioned regions. In all, 45 species belonging to 31 genera were recorded during the present survey, the maximum number of seaweed species were recorded at Thirumullavarum, Kerala with the minimum at Car Nicobar, Andaman and Nicobar Islands. A very different trend was observed in the case of biomass availability at some locations which was due to the influence of habitat suitability over the tsunami damage. The details of this study have been provided in the present communication  相似文献   

Townsend's Hypothesis, Coherent Structures And Monin–Obukhov Similarity     

K. G. McNaughton  Yves Brunet 《Boundary-Layer Meteorology》2002,102(2):161-175

Townsend's hypothesis states that turbulence near a wall can be divided into an activepart that transports momentum, and an inactive part that does not, and that these twokinds of turbulence do not interact. Active turbulence is generated by wind shear and has properties that scale on local parameters of the flow, while inactive turbulence isthe product of energetic processes remote from the surface and scales on outer-layerparameters. Both kinds of motion can be observed in the atmospheric surface layer, soMonin–Obukhov similarity theory, which is framed in terms of local parameters only,can apply only to active motions. If Townsend's hypothesis were wrong, so that activeand inactive motions do interact in some significant way, then transport processes nearthe ground would be sensitive to outer-layer parameters such as boundary-layer depth,and Monin–Obukhov theory would fail.Experimental results have shown that heat transport near the ground does depend onprocesses in the outer layer. We propose a mechanism for this whereby inactive motionsinitiate active, coherent ejection/sweep structures that carry much of the momentum andheat. We give evidence that the inactive motions take the form of streak patterns of fasterand slower air, and argue that these are induced by the pressure effects of large eddiespassing overhead. The streak pattern includes regions where faster streams of air overtakeand engulf slower-moving streaks. Transverse vortices form across the spines of the streaksat these places and some of them develop into horseshoe vortices. These horseshoe vorticesgrow rapidly and are rotated forward in the sheared flow so they soon contact the ground,squirting the air confined between the legs of the horseshoe vortex outwards as a forcefulejection. This model is consistent with a wide range of results from the field and laboratoryexperiments. Heat transport is significantly affected, so undermining the dimensionalassumptions of Monin–Obukhov similarity theory.  相似文献   

The colonization of periphytic diatom species on artificial substrates in the Ashar canal, Basrah, Iraq   总被引：1，自引：0，他引：1  

H.A. Hameed 《Limnologica》2003,33(1):54-61

Studies have been conducted between March 1993 and March 1994 in the Ashar canal, a backwater of the Shatt al-Arab River, Iraq. Using artificial substrates, the colonization and development of seventy-five diatom species belonging to twenty genera could be revealed. Taxa apportionment varied seasonally as well as within each season. A few species have been found during all experiments. These are Amphora ovalis, Bacillaria paradoxa, Cocconeis placentula var. euglypta, Cyclotella meneghiniana, Cymbella ventricosa, Navicula tripunctata var. schizonemoides, Rhoicosphenia curvata, and Synedra ulna. The occurrence of B. paradoxa in Experiment 1 (March-April 1993) and Experiment 4 (end of January to beginning of March 1994) was higher than 50%. Similarity of species increased towards the end of each season, and the communities from experiments 1 and 4 were more similar than others. The experiments also suggest that week 4 represents the equilibrium phase while week 6 reflects the increase in biological interactions. The results could also indicate the sequence of primary colonizers and the community development towards the equilibrium.  相似文献