The researches on species diversity and its relationship with spatial scale have remained a key topic in plant ecology.The results of researches on species diversity are always influenced by sampling strategy.In this ...The researches on species diversity and its relationship with spatial scale have remained a key topic in plant ecology.The results of researches on species diversity are always influenced by sampling strategy.In this paper,the modifiable areal unit problem(MAUP)of species diversity in natural secondary Alniphyllum fortunei forest in Meihuashan Natural Reserve was studied.The results showed that there were scale effect and zoning effect for species diversity in Alniphyllum fortunei community.With the increase of the sample area,the scale effect and zoning effect might decrease.Jackknifing method was able to estimate a normal distribution range of species diversity as well as the zoning effect range.展开更多
重构修正(correction procedure via reconstruction, CPR)是一种计算高效、模板紧致、适用于非结构网格的高阶方法,但是无法处理流场含有较强间断的问题。针对这个问题,前期基于二阶非等距非线性加权插值的激波捕捉格式以及非结构四边...重构修正(correction procedure via reconstruction, CPR)是一种计算高效、模板紧致、适用于非结构网格的高阶方法,但是无法处理流场含有较强间断的问题。针对这个问题,前期基于二阶非等距非线性加权插值的激波捕捉格式以及非结构四边形网格,发展了高阶CPR方法的一种子单元限制技术。该技术首先通过侦测因子确定出问题单元,然后将问题单元基于CPR求解点划分成非等距子单元,并在子单元中采用二阶激波捕捉格式进行计算。这种子单元限制技术保证了主单元和子单元的求解点重合,可以十分方便地处理主单元和子单元之间的数据交换。问题单元的侦测是该子单元限制技术的关键步骤,侦测出的问题单元的数量以及分布情况都将会影响数值结果。基于此,本文同时考虑了单元侦测和分维侦测两种问题单元侦测方式。通过激波管问题、Shu-Osher问题、双马赫反射问题、激波-旋涡干扰等典型算例对比分析了TVB、MDHE和JST侦测因子对数值格式分辨率的影响。研究结果表明:分维侦测能够减少问题单元的区域,进而提高分辨率。展开更多
文摘The researches on species diversity and its relationship with spatial scale have remained a key topic in plant ecology.The results of researches on species diversity are always influenced by sampling strategy.In this paper,the modifiable areal unit problem(MAUP)of species diversity in natural secondary Alniphyllum fortunei forest in Meihuashan Natural Reserve was studied.The results showed that there were scale effect and zoning effect for species diversity in Alniphyllum fortunei community.With the increase of the sample area,the scale effect and zoning effect might decrease.Jackknifing method was able to estimate a normal distribution range of species diversity as well as the zoning effect range.
文摘重构修正(correction procedure via reconstruction, CPR)是一种计算高效、模板紧致、适用于非结构网格的高阶方法,但是无法处理流场含有较强间断的问题。针对这个问题,前期基于二阶非等距非线性加权插值的激波捕捉格式以及非结构四边形网格,发展了高阶CPR方法的一种子单元限制技术。该技术首先通过侦测因子确定出问题单元,然后将问题单元基于CPR求解点划分成非等距子单元,并在子单元中采用二阶激波捕捉格式进行计算。这种子单元限制技术保证了主单元和子单元的求解点重合,可以十分方便地处理主单元和子单元之间的数据交换。问题单元的侦测是该子单元限制技术的关键步骤,侦测出的问题单元的数量以及分布情况都将会影响数值结果。基于此,本文同时考虑了单元侦测和分维侦测两种问题单元侦测方式。通过激波管问题、Shu-Osher问题、双马赫反射问题、激波-旋涡干扰等典型算例对比分析了TVB、MDHE和JST侦测因子对数值格式分辨率的影响。研究结果表明:分维侦测能够减少问题单元的区域,进而提高分辨率。