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991.
陈红 《广西师范学院学报(自然科学版)》2000,17(3):27-30
使用水污染损失率评价方法可以使对水体使用功能损害程度的评价具有鲜明的物理意义。对抚仙湖水体的评价表明,目前抚仙湖水质较好,用于饮用水源、养殖、游泳的损害率分别为2.06%、0.96%和1.95%,其它功能的损害度为0。 相似文献
992.
准格林函数方法在Winkler地基上简支平行四边形板中的应用 总被引:2,自引:1,他引:1
应用准格林函数方法,即利用方程的基本解和规范化的边界方程构造一个准格林函数,将W inkler地基上简支平行四边形薄板的弯曲问题化为两个耦合的第二类Fredholm积分方程,此积分方程的核表示式在区域的边界上具有奇异性.规范化的边界方程有多种选择,在选定一种规范化的边界方程的基础上,可以通过建立一个新的规范化的边界方程来表示问题的边界,从而克服了积分核的奇异性.数值算例表明,该方法具有较高的精度. 相似文献
993.
提出一种新的数值方法———准格林函数方法.以Pasternak地基上简支多边形薄板的弯曲问题为例,详细阐明了准格林函数方法的思想.即利用问题的基本解和边界方程构造一个准格林函数,这个函数满足了问题的齐次边界条件,采用格林公式将薄板的弯曲问题化为两个耦合的第二类Fredholm积分方程.边界方程有多种选择,在选定一种边界方程的基础上,可以通过建立一个新的规范化边界方程来表示问题的边界,以克服积分核的奇异性. 相似文献
994.
《Journal of Natural History》2012,46(45-48):2891-2917
The epibiont communities of the freshwater shrimp Caridina ensifera, endemic to Lake Poso (Sulawesi, Indonesia), were analysed for the first time based on their morphological and biometrical characteristics and taxonomic position. Seven ciliated protozoans and a rotifer were examined: three suctorian ciliate protozoan species (Acineta sulawesiensis, Podophrya maupasi, and Spelaeophrya polypoides), three peritrichs (Zoothamnium intermedium, Vorticella globosa, and Cothurnia compressa), a haptorid (Amphileptus fusidens), and the rotifer species Embata laticeps. A mean number of 314.6 epibionts was found per shrimp specimen. The distribution of the epibiont species on the surface of the basibiont was recorded, to allow calculation of the density on the different colonized individuals of C. ensifera and on each anatomical unit of the shrimp. The most abundant species, Zoothamnium intermedium and Acineta sulawesiensis, were also the ones most widely distributed. The statistical analysis showed that Zoothamnium, Acineta, Podophrya, and Embata were the epibiont genera most widely distributed on the basibiont, and the pairs of epibiont genera Zoothamnium–Embata, Podophrya–Acineta, Spelaeophrya–Amphileptus, and Cothurnia–Vorticella followed a similar pattern of distribution. There was a significant difference between the distribution patterns of the different epibiont species on the shrimp. The analysis of the densities of the epibionts throughout the longitudinal axis of the shrimp showed a gradient from the anterior to the posterior end of the body, and a significantly different distribution of each epibiont species. Their colonization follows a certain pattern of behaviour, the species occupying the available substratum, with particular requirements of each functional group, but with a trend resulting in equilibrium among species and groups, compensating for diversity and density. The possible adaptations of the epibionts, as well as the colonization patterns are discussed. 相似文献
995.
《Journal of Natural History》2012,46(10):1487-1512
The genus Platythelphusa is revised and six species are recognized. These species are P. armata A. Milne-Edwards, 1887, P. maculata (Cunnington, 1899), P. conculata Cunnington, 1907, P. tuberculata Capart, 1952, P. polita Capart, 1952 and P. echinata Capart, 1952. A seventh taxon, P. denticulata Capart, 1952 is considered here to be a junior synonym of P. conculata. A diagnosis for each species is provided and most are figured from the type. Keys to the families of African freshwater crabs and to the genus Platythelphusa are also provided. 相似文献
996.
Christina Prell Klaus Hubacek Claire Quinn Mark Reed 《Systemic Practice and Action Research》2008,21(6):443-458
Environmental applications of social network analysis (SNA) are just beginning to emerge, and so far have focussed on understanding
the characteristics of social networks that increase the likelihood of collective action and successful natural resource management.
We move beyond this discussion to demonstrate how knowledge gained from analysing the social networks of stakeholders can
be harnessed for selecting stakeholders, and further, how these analyses can be influenced by the expressed wishes and concerns
of stakeholders. Although we began our SNA using concepts derived from the resource-management literature, stakeholder involvement
in the interpretation of the results led to the use of SNA techniques that had not previously been applied in the context
of resource management. We thus re-analysed our data and modified our selection of research participants. Re-analysis led
to the selection of research participants who (1) had unique positions in the network, thus occupying non-redundant communication
roles in the network, (2) came from different stakeholder categories and (3) were relatively well-connected to others and
tended to broker across different segments of the network. By combining insights from researchers and stakeholders in this
way, it was possible to use SNA in an innovative and sensitive way to better meet the needs of the stakeholders and the research
project.
相似文献
Christina PrellEmail: |
997.
998.
刘春河 《科技情报开发与经济》2007,17(33):105-107
阐述了南寨公园建设项目的现状,探讨了规划及改建南寨公园的原则和依据,分析了建设南寨公园的迫切性,列举了建设南寨公园的条件,同时指出了规划设计的弊端。 相似文献
999.
提出了一种新的数值方法--准格林函数方法. 以Winkler地基上简支多边形薄板振动问题为例,阐明了准格林函数方法的思想. 即利用问题的基本解和边界方程构造一个准格林函数,该函数满足问题的齐次边界条件,采用格林公式将Winkler地基上薄板自由振动问题的振形控制微分方程化为两个耦合的第二类Fredholm积分方程. 边界方程有多种选择,在选定一种边界方程的基础上,可以通过建立一个新的边界方程来表示问题的边界,以克服积分核的奇异性. 最后由积分方程的离散化方程组有非平凡解的条件,求得固有频率. 数值算例表明,该方法具有较高的精度. 相似文献
1000.
基于国内外绿色水电指标体系及评价方法的相关研究,针对流域水电梯级开发环境保护特点和水电工程全生命周期管理,本文构建了3个层次且涵盖河流健康状况、环境管理和社会经济效益3方面的绿色水电综合评价指标体系,建立了绿色水电等级评定的改进的变权物元可拓模型.我们选择大渡河上已建成且投产运行时间较长的深溪沟水电站作为典型代表电站进行绿色水电实证分析,根据收集调查的基础数据计算得出各评价指标的得分,再运用改进变权物元可拓模型对该电站的绿色水电等级进行评定,并进一步对评价指标的敏感性进行分析,验证了所建绿色水电指标体系和评价模型的适用性和有效性.依据绿色水电评价分析成果,我们需要对流域水电开发环境管理进行优化完善,以进一步提高绿色水电评价等级,推进流域水电项目的健康可持续开发. 相似文献