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1.
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
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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
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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
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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
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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
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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
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特定基准下的异常位移诊断 总被引:1,自引:0,他引:1
针对地壳运动和变形研究中存在的位移资料的参考基准、异常位移等问题,主要讨论了位移资料特定基准的转换和异常位移诊断的数学模型——特定基准转换模型为七参数相似变换模型,转换保持了变形体内部相对位置关系不变,并使转换后的位移矢量更能体现区域内的相对运动信息;异常位移诊断采用拟准检定法(QUAD),在选定拟准观测的情况下,使得位移真误差具有明显的分群性;模拟算例结果显示,本文采用的线性变换模型、粗差拟准检定法都表现出很好的效果。 相似文献