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This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University. 相似文献
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People’s perception and socioeconomic determinants of soil erosion:A case study of Samanalawewa watershed,Sri Lanka 总被引：3，自引：0，他引：3
Though soil erosion is an important concern in Sri Lanka, there is a dearth of baseline information on soil erosion in many ofits watersheds, which obstructs monitoring of soil erosion and mitigating its effects. In order to assess soil erosion in a critical watershed and to identify its determinants, the Samanalawewa watershed, which contains one of the main hydropower generating reservoirs in Sri Lanka, was selected for this study. Remote-sensing (RS) and geographic information system (GIS) based modeling... 相似文献
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GE Renyan Doctoral Candidate School of Information Engineering WTUSM Wuhan China 《地球空间信息科学学报》1998,(1)
With the help of CCD images,the realization of high precision po-sitioning and measurement has become the basic standard for machine vision andreal time photogrammetry systems.However,deformation and other sorts ofdegradation occurring during transmission are major limiting factors of the preci-sion attainable with most current CCD cameras and frame grabbers.So a preciseradiometric and geometric transmission of images from CCD sensor to memory is afundamental aspect of CCD camera calibration.The geometric calibration system,which uses some image processing algorithms of the CCD camera based on the re-searched and developed system is discussed.The reliability and validity are alsodiscussed.The experimental results for the calibration of the CCD array will betaken as an important quality index for CCD evaluation. 相似文献
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TAO Chuang LIN ZongjianTAO Chuang Doctoral Candidate School of Information Engineering WTUSM Wuhan China 《地球空间信息科学学报》1998,(1)
We are involved in an embarrassing situation that the limited capa-bility of automated feature extraction in digital photogrammetric systems cannotsatisfy the increasing needs for rapid acquisition of semantic information for appli-cations.Facing this challenge,a new tactic,Human-Computer Collaborative（HCC）tactic,and a corresponding new method,Operator-Object Directed（OOD）method,are proposed for the design of a system for feature extractionfrom large scale aerial images.We hold that in almost all technical complex sys-tems,full automation will be neither technically feasible nor socially acceptable.The system should be designed to optimize through the cooperative operation withtwo agents in the system:the human and the computer. 相似文献
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SUN Haiyan Doctoral Candidate School of Geo-sci-ence Surveying Engineering WTUSM Wuhan China 《地球空间信息科学学报》1998,(1)
This paper deduced a more general error distribution,the p-th pow-er norm distribution,based on the foundational properties of random errors. 相似文献
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Effect of streambed sediment on benthic ecology 总被引：5，自引：2，他引：3
Xuehua DUAN Zhao-Yin WANG Mengzhen XU Kang ZHANG Ph.D. Jiangyin Environmental Monitoring Station Jiangyin China Dept. of Hydraulic Engineering Tsinghua University Prof. State Key Laboratory of Hydroscience Engineering Beijing Doctoral c idate Doctoral c idate Be... 《国际泥沙研究》2009,24(3):325-338
Benthic macroinvertebrates have been commonly used as indicator species for assessment of aquatic ecology. Streambed sediment, or substrate, plays an important role in habitat conditions for macroinvertebrate communities. Field investigations were done to study the benthic diversity and macroinvertebrate compositions in various stream substrata. Sampling sites with different bed sediment, latitude, and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River, in China. The results show that benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are similar. The study, thus, demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow conditions, but is generally unaffected by latitudinal position and macroclimate. Taxa richness of the maeroinvertebrate community was found to be the highest on hydrophyte-covered cobbles, high on moss-covered bedrock, and low on clay beds and cobble beds devoid of plant biomass. Sandy beds are compact and unstable, thus, no benthic macroinvertebrates were found colonizing such substrata. Aquatic insects account for most of the macroinvertebrates collected in these rivers. Different insects dominate in different types of substrata： mainly EPT species （Ephemeroptera, Ptecoptera, Tfichoptera） in cobble, gravel, and moss-covered bedrock; and Chironomidae larvae in clay beds. The relation between the number of species in the samples and the size of the sampling area fits a power function of the species area. One square meter （lm） is suggested as the minimum sampling area. A substrate suitability index is proposed by integrating the suitability of sediment, periphyton, and benthic organic materials for macroinvertebrates. The biodiversity of macroinvertebrates increases linearly with the substrate suitability index. Benthic taxa richness increases linearly with the suitability index. 相似文献
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