材料表面非线性振荡时间序列的相空间重构     

陈泉水  黄斌 《华东地质学院学报》2005,28(1):34-38

在许多固态材料的表面存在着一种天然的非线性振荡花样，这些花样经计算机图像处理在时间和空间上呈现明显的分形特征。利用普通光学显微镜对Cu—Zn—Al合金表面的金相组织进行观察和分析，用高速摄像机拍摄了典型的振荡现象。借助计算机图像处理技术系统地研究该非线性振荡现象的形貌、结构特征及形成动力学规律，通过计算机编程技术构建系统的非线性动力模型，并重构系统的相空间。用R／S方法对系统时间序列的演化特征进行分析论证，结果表明，这种相空间重构方法具有较好的非线性预报效果。  相似文献   

A Polygenetic Landform At Stígá, Öræfajökull, Southern Iceland     

Tim Harris  Fiona S. Tweed  Óskar Knudsen 《Geografiska Annaler: Series A, Physical Geography》2004,86(2):143-154

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Photogrammetric Reconstruction of the Great Buddha of Bamiyan, Afghanistan     

Armin Grün  Fabio Remondino  Li Zhang 《The Photogrammetric Record》2004,19(107):177-199

In the valley of Bamiyan, Afghanistan, approximately 1700 years ago, two large standing Buddha statues were carved out of the sedimentary rock of the region. They were 53 and 38 m high and the larger one figured as the tallest representation of a standing Buddha in the world. In March 2001 the Taleban government militia demolished the colossal statues. After the destruction a group from ETH Zürich completed the computer reconstruction of the Great Buddha, which can serve as the basis for a physical reconstruction. This paper reports the results of the image-based 3D reconstruction of the statue, performed on three different data-sets in parallel and using different photogrammetric techniques and algorithms.  相似文献   

基于航空立体影像对的复杂房屋三维拓扑重建   总被引：1，自引：1，他引：1  

邵振峰  李德仁  程起敏 《武汉大学学报(信息科学版)》2004,29(11):999-1003

对利用航空影像对重建复杂房屋三维模型进行了研究，提出了拓扑链、外拓扑和内拓扑的概念，分析了复杂房屋的内拓扑和外拓扑的三维重建，构造了复杂房屋的三维拓扑数据模型。基于此模型设计了双向搜索算法，用于自动构建复杂房屋的三维拓扑面，从而实现了复杂房屋的自动三维拓扑重建。实验证明，本文提出的双向搜索算法是很稳健、高效的。  相似文献   

Development of a Robust Photogrammetric Metrology System for Monitoring the Healing of Bedsores     

Abbass  Malian  Ali  Azizi  Frank A.  van den Heuvel  Mahmoud  Zolfaghari 《The Photogrammetric Record》2005,20(111):241-273

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广义点摄影测量及其应用   总被引：28，自引：3，他引：28  

张祖勋  张剑清 《武汉大学学报(信息科学版)》2005,30(1):1-5

将传统的点摄影测量与当代发展的线摄影测量以及无穷远点理论综合升华为广义点摄影测量理论。论述了广义点摄影测量理论。介绍了其应用。包括由灭点计算影像参数及单像建模。由矢量与影像的匹配确定影像的参数，钣金件的检测与由轮廓线匹配确定飞机的姿态等。  相似文献   

华北地区500年滑动平均降水场序列重建     

荣艳淑  屠其璞 《气象科技》2004,32(3):163-167

基于533年旱涝指数场序列，采用了滑动累积频率法用于降水序列重建工作，并选用了3种不同均值用于序列重建试验，得到了1499～2002年共504年连续的滑动平均降水场序列。分析表明，重建的504年降水场序列与49年实测降水场序列相关性较好，其平均相对均方误差在1．89％以下；重建的序列与原旱涝指数序列的非线性关系，表明重建序列是合理的，为华北地区长期旱涝变化规律的研究提供了基础资料。  相似文献   

一类广义Radon变换的反演:迭代重建再投影的外插算法   总被引：1，自引：0，他引：1  

张兆田  邱佩璋 《CT理论与应用研究》1993,(3)

本文对不完全数据下的一类广义Radon变换的反演问题,建议用迭代重建再投影的外插算法重建图像。数值模拟结果表明,迭代重建再投影的外插算法对重建图像是有效的。  相似文献   

Comparison of taxon calibrations,modern analogue techniques,and forest-stand simulation models for the quantitative reconstruction of past vegetation     

Hazel R. Delcourt  Paul A. Delcourt 《地球表面变化过程与地形》1985,10(3):293-304

We compared results of three quantitative methods for reconstructing past vegetation, including (1) calibrations of per cent dominance vs. per cent pollen for individual tree taxa; (2) coefficients of dissimilarity between fossil and modern pollen assemblages; and (3) simulation modelling of long-term forest succession. For calibration, we used 1684 modern pollen samples and 1742 forest-inventory summaries from eastern North America. We applied the calibrations at 1 000-year intervals to the 19000-year pollen record from Anderson Pond, Tennessee. Dominance values reconstructed using taxon calibrations typically paralleled the changes in percentages of arboreal pollen. Dissimilarity values between fossil and modern pollen assemblages were lowest from 19 000 yr BP to 15 000 yr BP and from 9 000 yr BP to the present, indicating good modern analogues for both full-glacial and Holocene time periods. During times of good analogue, forest composition estimated from forest inventories at the locations of best pollen analogues was similar to that reconstructed using taxon calibrations. Relatively poor modern analogues exist for late glacial and early Holocene pollen spectra from Anderson Pond. During times of poor analogues, forest composition reconstructed from taxon calibrations differed from that derived from analogue methods. FORET-model simulations of forest-stand biomass differed markedly from palaeovegetation estimates made from the other two methods. This is primarily because the FORET model is scaled to forest succession on 1/12-ha forest plots rather than forest dynamics integrated over a broad landscape mosaic. Because they are based upon fundamental relationships of pollen production and dispersal, taxon calibrations provide the best available means for reconstructing forest history both during times of good and of poor analogues.  相似文献   

一种改进的三维点集表面重建的区域生长算法   总被引：3，自引：0，他引：3  

朱庆  李逢春  张叶廷 《武汉大学学报(信息科学版)》2006,31(8):667-670

介绍了一种改进的三雏点集表面重建的区域生长算法。提出了一种基于三角形任意一边邻域拓扑关系的邻接三角形定位方法，充分利用了法向信息，采用由粗到精的提取策略，减少了候选表面三角形的数量，显著加快了表面重构的整体效率。提出了相应的局部拓扑一致性检测方法，确保了算法的稳健性，解决了传统算法的重叠面片和表面空洞等问题，并且重构的三角网格表面与被采样的物体表面拓扑差别最小。实验结果表明，本文算法可以重构具有任意拓扑的复杂表面。  相似文献