多源遥感影像误匹配点剔除的粗糙模糊C-均值方法     

李参海  王光辉 《测绘与空间地理信息》2008,31(5)

简要概述了遥感影像匹配中,误匹配点剔除的常用方法.对SIFT特征描述子生成及其匹配、粗糙模糊C-均值方法聚类分析的原理方法进行了详细论述.针对SIFT方法匹配出的大量点对,将不同时相,不同传感器、不同分辨率影像广义划分为同分辨率和不同分辨率.基于同分辨率影像匹配点对问连线具有相同的距离及斜率、不同分辨率影像匹配点对间连线的延长线交于一点的几何约束条件,利用粗糙模糊C-均值模型聚类分析方法对点对快速剔除误匹配点后,对剔除的结果利用最小二乘方法进行精匹配,结果达到亚像素.最后,通过对不同时相、不同分辨率、不同传感器的多源遥感影像实验分析验证了该方法的适用性、可靠性及精确性.  相似文献   

Preserved paleo-oceanic plateaus in accretionary complexes: Implications for the contributions of the Pacific superplume to global environmental change   总被引：1，自引：1，他引：0  

Atsushi Utsunomiya  Norihito Suzuki  Tsutomu Ota 《Gondwana Research》2008,14(1-2):115

We have reinvestigated the mid-Cretaceous plume pulse in relation to paleo-oceanic plateaus from accretionary prisms in the circum-Pacific region, and we have correlated the Pacific superplume activity with catastrophic environmental changes since the Neoproterozoic. The Paleo-oceanic plateaus are dated at 75–150 Ma; they were generated in the Pacific superplume region and are preserved in accretionary prisms. The volcanic edifice composed of both modern and paleo-oceanic plateaus is up to 10.7 × 10⁶ km² in area and 19.1 × 10⁷ km³ in volume. The degassing rate of CO₂ (0.82 − 1.1 × 10¹⁸ mol/m.y.) suggests a significant impact on Cretaceous global warming. The synchronous occurrence of paleo-oceanic plateaus in accretionary complexes indicates that Pacific superplume pulse activities roughly coincided at the Permo-Triassic boundary and the Vendian–Cambrian boundary interval. The CO₂ expelled by the Pacific superplume probably contributed to environmental catastrophes. The initiation of the Pacific superplume contributed to the snowball Earth event near the Vendian–Cambrian boundary; this was one of the most dramatic events in Earth's history. The scale of the Pacific superplume activity roughly corresponds to the scale of drastic environmental change.  相似文献   

《中国21世纪议程》与西北持续发展     

徐金发 《干旱区地理》1996,19(1):58-60

本文概要介绍了我国２１世纪发展白皮－《中国２１世纪议程》;全面列举了国际社会对西北地区第一批优先项目支持的承诺,勾勒了西北地区“可持续发展之路”的轮廓。  相似文献   

坡地农林复合系统的结构类型与效益分析─以长江三峡库区坡地农业为例   总被引：4，自引：0，他引：4  

申元村  彭业轩 《地理研究》1995,14(3):43-51

本义认为现代术语的农林复合系统来源于生产实践,体现了农业与林业的有机结合、品种生态和经济的有机结合、产品多样化以及管理科学化4个方面相统一的特点。文章在分析三峡库区农林复合系统的类型结构基础上,提出了农林复合系统可以进行层次结构划分的观点。最后,以典型案例研究方法入手,对1种农林结构类型进行效益分析,结果表明,采用植物篱农林复合坡地系统,是现阶段生产力水平下实现坡地生态经济协调发展的有效途径,值得广泛推广。  相似文献   

用气象站地温资料计算多年平均土壤热流的初步结果   总被引：11，自引：3，他引：8  

董文杰  汤懋苍 《高原气象》1992,11(2):115-125

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珠江三角洲城市旅游竞争力空间结构体系初探   总被引：37，自引：4，他引：37  

黄耀丽  李凡  郑坚强  李飞 《地理研究》2006,25(4):730-740

区域城市间旅游竞争力空间结构体系是一个由不同等级、不同空间区位、不同旅游发展阶段的城市通过旅游资源、旅游交通等生产力要素以及客流有机耦合而形成的。本文在深入分析旅游竞争力含义及其空间结构的基础上,采用城市旅游竞争力的多维评价和综合分析的方法,将珠江三角洲城市旅游目的地划分为不同的3个等级,并总结出珠江三角洲城市旅游竞争力具有以广深为轴线的“哑铃”型双极放射状空间形态模式,提出了凭借城市自身比较优势,承担不同层次旅游竞争与合作角色的空间组织模式,旨在通过研究梳理各城市旅游影响要素的优劣差异,认识区域内旅游竞争力的空间结构特征,为进一步探讨形成互利共赢的城市旅游竞争与合作机制奠定基础,促进珠江三角洲城市旅游经济的和谐发展。  相似文献   

Erratum “Boundary” in ancient Persian tradition of statehood: an introduction to the origins of the concept of boundary in pre-modern history     

Pirouz Mojtahed-Zadeh 《GeoJournal》2006,66(4):273-283

Erratum to: GeoJournal 62: 51–58 DOI 10.1007/s10708-005-8562-2 The erroneous version of this article was originally published in GeoJournal 62: 51–58. This amended version corrects the formatting errors which are evident in the original version.Abstract It is universally accepted that the need for defining precise lines of separation and points of contacts between states is the byproduct of the emergence of nation-states and ‘world economy’ in the nineteenth century Europe. Nevertheless, it is hard to overlook the fact that these modern notions are rooted in periods prior to the emergence in Europe of nation-states. There are indications that ancient civilizations were familiar with the notion of ‘state’ in connection with the concepts of territory and boundary. Ancient texts reveal that this basic principle existed in ancient Persian literature in respect of matters of state, territory, and boundary. Similarly, the likelihood exists that these Persian notions could have influenced Roman civilization. It is widely believed that a combination of ancient Greco-Roman and Persian civilizations is a major contributor to what culturally constitutes ‘West’. Later in the Sassanid period the inter-linked notions of state, territory, and boundary developed substantially, coming quite close to their contemporary forms. On the other hand, considering that ‘justice’ was the corner stone of ancient Persian Political philosophy, the idea that ancient␣Iranian spatial arrangement might have contributed to the evolution of the concept of democracy in the West may not be too difficult to contemplate.The online version of the original article can be found at  相似文献   

黄河源地区草地退化空间特征   总被引：54，自引：4，他引：54  

张镱锂  刘林山  摆万奇  沈振西  阎建忠  丁明军  李双成  郑度 《地理学报》2006,61(1):3-14

利用黄河源地区1985年和2000年1：100000土地利用／覆被数据，结合1：250000DEM、道路和居民点数据与野外调查资料，分析草地退化与坡向、海拔及距道路和居民点距离之间的关系．探讨黄河源区15年间土地覆被变化特征与规律。结果表明，退化草地占源区总面积的8．24％，冬春季牧场退化率显著高于夏季牧场：草地退化是黄河源区研究时段内土地利用／覆被变化最主要的特征。草地退化表现为：①阳坡退化率高于阴坡；②受人口密度影响，草地退化率与海拔高度成反比，相关系数为．0．925；③距离居民点越近。退化率越高。尤其当与居民点距离≤12km时，草地退化率与其相关系数高达-0．996；④在距道路4km以内．草地退化率与道路距离成反比．相关系数高达-0．978。1985年以来，源区的草地退化有自然因素的影响．但人类活动的影响仍起主导作用。科学地减少当地居民对草地的过分依赖是解决脆弱的江河源区环境退化的根本。  相似文献   

Gender and voluntary work in late adulthood in rural communities in the Netherlands     

Joos Droogleever Fortuijn  Marieke van der Meer 《GeoJournal》2006,65(4):381-392

This article discusses the involvement of older women and men in voluntary work in rural communities in the Netherlands. Gender, ageing and civil society form the core concepts in the article. Politicians and policy makers in the Netherlands are worried about the perceived decline of civil society and about the consequences of this decline for specific categories of older women in terms of well-being and social exclusion. The paper presents the results of two surveys of involvement of older women and men in civic organisations, voluntary work and local actions. The surveys indicate high levels of involvement of both women and men. No gender differences are found in activity level. However, the data demonstrate the gendered nature of civil society. Women are more engaged in informal voluntary work and informal local actions, while men are more active in formal organisations and functions. This gender segmentation is not absolute, however. Many older women and men transgress the traditional feminine–masculine boundaries. The surveys highlight the involvement of women and men in rural communities, but indicate lower activity levels in urban areas.  相似文献   

Dissolved trace elements in river water: spatial distribution and the influencing factor, a study for the Pearl River Delta Economic Zone, China   总被引：1，自引：0，他引：1  

T. P. Ouyang  Z. Y. Zhu  Y. Q. Kuang  N. S. Huang  J. J. Tan  G. Z. Guo  L. S. Gu  B. Sun 《Environmental Geology》2006,49(5):733-742

Twenty-nine water samples were collected from different river channels of the Pearl River Delta Economic Zone, China. An inductively coupled plasma-mass spectromonitor (ICP-MS) was used to measure concentrations of the trace elements in these samples. The results suggest that the average concentrations of rare earth elements in river water show an increasing trend from the West River, the North River, the rivers of the Pearl River Delta, and the Shenzhen River to the East River. Relatively high concentrations of heavy metals appear in the East River, the rivers of the Pearl River Delta and the Shenzhen River, while the West River and the North River have relatively low heavy metal concentrations. Trace element concentrations in samples collected near urban or industrial areas are much higher than those of samples collected from distant areas, away from urban and industrial areas. After natural conditions, human activities have significant influence on the trace element concentrations in river water. This trace element concentration’s spatial distribution in the river water from the Pearl River Delta Economic Zone is actually an integrated effect of natural conditions and human activity.  相似文献