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基于不同FFT算法的方形环带菲涅耳衍射场分布 被引量:1
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作者 韩振海 《物理实验》 2015年第11期32-36,共5页
利用标量衍射理论和快速傅里叶变换方法,对平面光波通过方形环带产生的衍射场进行了计算机模拟实验.模拟实验采用了3种不同的FFT方法,比较分析了其对应的衍射结果有所不同,并和实际的衍射实验结果进行了对比,进一步验证了相关文献中与... 利用标量衍射理论和快速傅里叶变换方法,对平面光波通过方形环带产生的衍射场进行了计算机模拟实验.模拟实验采用了3种不同的FFT方法,比较分析了其对应的衍射结果有所不同,并和实际的衍射实验结果进行了对比,进一步验证了相关文献中与选择算法有关的衍射特征距离判据. 展开更多
关键词 方形环带 菲涅尔衍射 傅里叶变换 计算机模拟
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Morphological Characteristics and Environmental Implications of Phytoliths in Topsoils from Different Vegetation Zones on Northern Slope of Changbai Mountains,China
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作者 QIAO Zhihe JIE Dongmei +2 位作者 LIU Hongmei GE Yong ZHANG Hongyan 《Chinese Geographical Science》 SCIE CSCD 2010年第6期506-512,共7页
The Changbai Mountains,located in the temperate monsoon climate zone of East Asia,is an ideal loca-tion for the research on timberline response to global changes.In this study,the topsoils were collected from differen... The Changbai Mountains,located in the temperate monsoon climate zone of East Asia,is an ideal loca-tion for the research on timberline response to global changes.In this study,the topsoils were collected from different vertical vegetation zones on the northern slope of the Changbai Mountains,Northeast China in August 2009,and phytoliths in the soil samples were extracted by using wet oxidation method and identified with Motic 2.0 microscope in laboratory.The results show that phytoliths are abundant in the topsoils of the study area.The herbal phytoliths are primarily composed of elongated,tooth-shaped,point-shaped and hat-shaped phytoliths,as well as a small amount of fan-shaped and square-shaped ones.The elongated,tooth-shaped,point-shaped and hat-shaped phytoliths are representative of cold climate,while fan-shaped and square-shaped ones are representative of warm and humid climate.In the conifer broadleaved mixed forest zone,coniferous forest zone and broadleaf forest zone,there are close correlations between vegetation and woody phytoliths in the topsoils,indicating that the woody plants of a region can be reconstructed from the woody phytolith assemblages in the topsoils.Meanwhile,the topsoil phytolith assemblages can also be used to reconstruct the understory herbs effectively.The phytolith assemblages in the topsoils of the forest community and herbal community differ significantly,which can help indicate the historical location of the timberline. 展开更多
关键词 topsoil phytolith TIMBERLINE environmental implication vertical vegetation zones Changbai Mountains
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