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主成分分析法和稳定度指数法评价森林群落稳定性比较 被引量:26
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作者 闫东锋 王向阳 杨喜田 《河南农业大学学报》 CAS CSCD 北大核心 2011年第2期166-171,182,共7页
基于森林群落稳定性评价理论,以宝天曼国家级自然保护区内的栎类天然次生林群落为研究对象,选择反映森林群落抵抗力、恢复力、持久性的评价指标(共15个),构建主成分分析和稳定度指数评价模型,计算相应的综合评价值和稳定度指数,以此分... 基于森林群落稳定性评价理论,以宝天曼国家级自然保护区内的栎类天然次生林群落为研究对象,选择反映森林群落抵抗力、恢复力、持久性的评价指标(共15个),构建主成分分析和稳定度指数评价模型,计算相应的综合评价值和稳定度指数,以此分别评价了群落稳定性,并对所得的结果进行了比较分析.结果表明,宝天曼地区栎类天然次生林群落总体处于稳定状态;对群落稳定性影响较大的指标为幼苗数量、林分密度和乔木物种多样性;两种模型评价结果都符合当地的森林群落发育情况,且在总体趋势上是一致的,但主成分分析法还可对评价指标的权重及其相互关系进行分析,评价过程可操作性强,具有较好的推广应用价值. 展开更多
关键词 主成分分析 稳定度指数法 群落稳定 评价指标体系 宝天曼
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Contributions to Hom-Schunck optical flow equations-part I: Stability and rate of convergence of classical algorithm 被引量:3
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作者 DONG Guo-hua AN Xiang-jing FANG Yu-qiang HU De-wen 《Journal of Central South University》 SCIE EI CAS 2013年第7期1909-1918,共10页
Globally exponential stability (which implies convergence and uniqueness) of their classical iterative algorithm is established using methods of heat equations and energy integral after embedding the discrete iterat... Globally exponential stability (which implies convergence and uniqueness) of their classical iterative algorithm is established using methods of heat equations and energy integral after embedding the discrete iteration into a continuous flow. The stability condition depends explicitly on smoothness of the image sequence, size of image domain, value of the regularization parameter, and finally discretization step. Specifically, as the discretization step approaches to zero, stability holds unconditionally. The analysis also clarifies relations among the iterative algorithm, the original variation formulation and the PDE system. The proper regularity of solution and natural images is briefly surveyed and discussed. Experimental results validate the theoretical claims both on convergence and exponential stability. 展开更多
关键词 optical flow Hom-Schunck equations globally exponential stability convergence convergence rate heat equations energy integral and estimate Gronwall inequality natural images REGULARITY
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