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传统的土地用途分区方法存在受人为因素影响、效率低下的问题,不利于土地用途分区管制的实施,基于GIS的智能化的土地用途分区系统则可以弥补这一缺陷。本文以GIS相关理论和土地用途分区的需求分析为基础,构建了系统的逻辑框架,研究了数据库、模型库、算法库和知识库的设计方案,提出了土地用途分区过程中的空间数据整合、目标函数和分区模型的选择等问题的解决方案,并实现了面向土地用途分区的空间聚类系统。以典型地区的土地用途分区为例,验证了该空间聚类系统是一种智能、高效、科学的土地用途分区平台。 相似文献
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"一带一路"沿线地区包括了我国最重要的国际能源供给区域,也是我国能源通道面临风险最集中的地区。本文针对"一带一路"沿线12个石油供给国,基于与中国石油贸易合作的视角,从收益和风险两个维度分别构建评价体系,综合分析中美日俄等大国的能源地缘政治格局,构建中国国际石油合作收益—风险矩阵。研究发现:从合作收益来看,与沙特阿拉伯未来开展大规模石油合作收益最高,其次为俄罗斯。从风险的评价来看,与伊拉克合作风险最高,其次为阿塞拜疆和伊朗。通过收益—风险矩阵,将所有国家划分为高风险—高收益、低风险—高收益、高风险—低收益、低风险—低收益四类,其中沙特阿拉伯、俄罗斯、科威特、哈萨克斯坦为高收益低风险国家,可作为优选合作对象; 相似文献
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We investigated the allelopathic properties of Alexandrium tamarense (Laboar) Balech on the growth of Prorocentrum donghaiense Lu, Chattonella marina (Subrahmanyan) Hara et Chihara and Heterosigma akashiwo (Hada) Hada in a laboratory experiment. We examined the growth of A. tamarense, C. marina, P. donghaiense and H. Akashiwo in co-cultures and the effect of filtrates from A. tamarense cultures in various growth phases, on the three harmful algal bloom (HAB)-forming algae. In co-cultures with A. tamarense, both C. marina and H. akashiwo were dramatically suppressed at high cell densities; in contrast, the growth of P. donghaiense varied in different inoculative ratios of A. tamarense and P. donghaiense. When the ratio was 1:1 (P. donghaiense: A. tamarense), growth of P. donghaiense was inhibited considerably, while the growth of P. donghaiense was almost the same as that of the control when the ratio was 9:1. The growth difference of P. donghaiense, C. marina and H. akashiwo when co-cultured with A. tamarense indicated that the allelopathic effect may be one of the important factors in algal competition and phytoplankton succession
involving A. tamarense. In addition, the filtrate from A. tamarense culture had negative impacts on these three HAB algae, and such inhibition varied with different growth phases of A. tamarense in parallel with reported values of PSP toxin content in Alexandrium cells. This implied that PSP toxin was possibly involved in allelopathy of A. tamarense. However, the rapid decomposition and inactivation of PSP toxin above pH 7 weakened this possibility. Further studies on
the allelochemicals responsible for the allelopathy of A. tamarense need to be carried out in future. 相似文献
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