Geostatistical Mapping with Continuous Moving Neighborhood   总被引：1，自引：0，他引：1  

Alexander Gribov  Konstantin Krivoruchko 《Mathematical Geology》2004,36(2):267-281

An issue that often arises in such GIS applications as digital elevation modeling (DEM) is how to create a continuous surface using a limited number of point observations. In hydrological applications, such as estimating drainage areas, direction of water flow is easier to detect from a smooth DEM than from a grid created using standard interpolation programs. Another reason for continuous mapping is esthetic; like a picture, a map should be visually appealing, and for some GIS users this is more important than map accuracy. There are many methods for local smoothing. Spline algorithms are usually used to create a continuous map, because they minimize curvature of the surface. Geostatistical models are commonly used approaches to spatial prediction and mapping in many scientific disciplines, but classical kriging models produce noncontinuous surfaces when local neighborhood is used. This motivated us to develop a continuous version of kriging. We propose a modification of kriging that produces continuous prediction and prediction standard error surfaces. The idea is to modify kriging systems so that data outside a specified distance from the prediction location have zero weights. We discuss simple kriging and conditional geostatistical simulation, models that essentially use information about mean value or trend surface. We also discuss how to modify ordinary and universal kriging models to produce continuous predictions, and limitations using the proposed models.  相似文献   

新城市主义对我国郊区城市化的借鉴   总被引：10，自引：0，他引：10  

王琳  曹嵘  白光润 《世界地理研究》2001,10(4):81-86

“新城市主义”是基于对郊区蔓延的反思，90年代在美国兴起的一个城市设计流派。本文介绍了新城市主义的主要设计思想，总结了其优点与不足，并提出了这一规划设计思想对于我国解决城市蔓延问题及城市郊区建设中的借鉴意义。  相似文献   

Neighborhood Activism among Homeowners as a Politics of Space     

Mark Purcell 《The Professional geographer》2001,53(2):178-194

Most approaches to neighborhood activism among homeowners explain it in terms of a single social variable, such as class or race or gender. This article argues that, by focusing on one social category, these approaches fail to examine the range of variables that influence homeowner activism. The paper argues that, instead of understanding homeowner activism as a politics of class or race or gender, it should be understood as a politics of space. Such an approach allows us to understand how social variables interrelate in homeowners’ political project and provides a more effective explanation for why this agenda is translated into action.  相似文献   

Hamilton无爪图的一个充分条件     

朱卓宇  孙学红 《南京气象学院学报》1997,20(2):178-180

设Ｇ是阶为ｎ，连通度ｋ的简单无爪图，证明了如果对每一个阶为ｋ＋１的独立集Ｓ中的每一对点，ｕｖ，都有│Ｎ（ｕ）∪Ｎ（ｖ）│≤ｎ－ｋ－Δ（Ｓ），则Ｇ是Ｈａｍｉｌｔｏｎ图。  相似文献   

Influence of 850 mb trajectories on acid precipitation in southwestern British Columbia     

M. S. Kotturi  T. S. Murty  M. B. Danard 《Natural Hazards》1991,4(1):45-55

Precipitation chemistry in southwestern British Columbia has been examined to determine if the shutdown of the ASARCO smelter in Tacoma, Washington in March of 1985 had a significant effect.The smelter emitted about 300 tonnes/day of sulphur dioxide and about one tonne/day of arsenic. The smelter had a supplementary control system (SCS) which was implemented during adverse meteorological conditions to meet ambient air standards. The SCS was in operation in October 1984.Five storms from October 1984, before the shutdown, that produced precipitation over the eight-station network in southwestern British Columbia, were considered. The 850 mb back trajectories and ionic loadings in the collected precipitation samples were compared. A similar comparison was made for three storms in October 1985, after the shutdown of the smelter. An examination of cases whose trajectories passed over the smelter before and after the shutdown indicated an over 50% decrease in volume weighted average sulphate concentration in precipitation over the Gulf Islands (islands in the southern Strait of Georgia). However, when the trajectory from the northwest passes over British Columbia coastal sources, higher excess SO₄ concentrations were observed in the precipitation over the Gulf Islands, indicating a linkage between these concentrations and the British Columbia coastal sources. There was no apparent change in values at stations farthest from the Strait of Georgia with one exception. It was also noted that there was reduction in arsenic in precipitation, which could be considered as a tracer, after the shutdown of the ASARCO smelter. This paper enlarges on the above observation with comparisons of the major meteorological and chemical characteristics related to eight storms.  相似文献   

基于S-域的空间关联规则挖掘研究     

杨晓梅  蓝荣钦  杨松 《测绘学院学报》2007,(1)

概括了空间关联规则挖掘的发展现状,引入空间共生域的概念,给出了相关论证,设计了详细的算法步骤。利用该方法可以分割地理连续体、实现数据的离散化处理,由此构造的空间数据库可以应用传统的Apriori算法。同时,针对共生域的异质性问题,给出了障碍距离的模糊隶属度公式。最后,结合应用实际进行挖掘,结果表明该方法适合于发现具有因果关系的空间实体之间的关联性知识。  相似文献   

Residential Burglaries and Neighborhood Socioeconomic Context in London,Ontario: Global and Local Regression Analysis*     

Jacek Malczewski  Anneliese Poetz 《The Professional geographer》2005,57(4):516-529

The main aim of this article is to analyze the relationships between the spatial patterns of residential burglaries and the socioeconomic characteristics of neighborhoods in London, Ontario. Relative risk ratios are applied as a measure of the intensity of residential burglary. The variation in the risks of burglary is modeled as a function of contextual neighborhood variables. Following a conventional (global) regression analysis, spatial variations in the relationships are examined using geographically weighted regression (GWR). The GWR results show that there are significant local variations in the relationships between the risk of residential burglary victimization and the average value of dwellings and percentage of the population in multifamily housing. The results are discussed in the context of four hypotheses, which may explain geographical variations in residential burglary. The practical implication of the GWR analysis is that different crime prevention policies should be implemented in different neighborhoods of the city.  相似文献   

A model of a heterogeneous neighborhood   总被引：1，自引：0，他引：1  

Izhak?SchnellEmail author  Moshe?Harpaz 《GeoJournal》2005,64(2):105-115

Tel Aviv is a highly ethnic city in which ethnicity is deeply embedded in people’s perceptions of their social milieus. Shapira, as one of the most heterogeneous neighborhoods in Tel Aviv, supplies a unique demonstration of the inadequacy of the Chicago model, which assumes the emergence of homogeneous neighborhoods. The study shows that ethnicity is exercised as a major force in determining social life in Shapira. Interactive segregation indices reveal that residents of Shapira tend to prefer intra-ethnic social networks although two-thirds of them maintain inter-ethnic networks as well. Despite this, residential and activity spaces are highly heterogeneous. Residential spaces are heterogeneous on all scales from residents’ immediate surroundings to the block and the neighborhood as a whole. In most buildings one may find neighbors from two or three different ethnic groups with only non-Jewish residents excluded from publicly owned buildings. Most residents perform large part of their everyday life outside the neighborhoods in ethnically heterogeneous surroundings, but nonetheless in choosing their more meaningful partners for social networks they choose them from their ethnic groups. The fact that residents tend to perform a large part of their activities out of their neighborhood, and to live in heterogeneous surroundings in social categories that are perceived by them salient to their daily life, does not undermine the relevance of the neighborhood as a socially constituted entity in the urban field. People organize and act in order to improve life conditions in the neighborhood, they feel sense of attachment to the neighborhood and they develop some local social networks in the neighborhood.  相似文献   

海底沙波特征线的最优方向剖面自动识别方法   总被引：2，自引：2，他引：0  

周洁琼  吴自银  赵荻能  尚继宏  李守军  梁裕杨  周勐佳 《海洋学报》2015,37(7):97-107

海底沙波是发育在近海陆架上的一种常见海底地貌类型,海底沙波特征与运动规律的研究具有重要的科学意义与工程应用价值,沙波脊线与谷线是表征海底沙波的最基本特征,也是精确描述沙波运动的基本参量。本文提出了一种基于复合数字水深模型的沙波特征线自动识别方法——最优方向剖面法,基于水深曲面归算得到最优剖面方向,再依据最优剖面方向求导并判定极值,自动提取沙波形态特征点,最终形成沙波脊线和谷线。以台湾浅滩复合型沙波为例进行对比实验研究,结果表明,该方法能基于不同分辨率的数字水深模型自动准确地提取海底沙波脊线与谷线,勿需设置阈值,地形自动化识别程度得到进一步提升,具有重要的实际应用价值。  相似文献   

结合邻域SAC-NED测度的高光谱图像分类方法     

张斌  朱述龙  孟伟灿  曹彬才  宋新阳 《测绘科学技术学报》2015,(6):600-604

提出了一种光谱相似性测度用于高光谱图像分类方法。通过将光谱向量进行归一化处理,将计算得到的欧氏距离与光谱角余弦的值域归化到相同区间,得到光谱角余弦与欧氏距离联合测度值(SAC-NED)。在对图像像元进行分类时,以距离加权的方式将邻域像元参与中心像元SAC-NED值的计算,将像元分到SAC-NED值最大的类别。通过与其他5种常用相似性测度方法的实验结果对比表明:该算法能够提升高光谱图像分类的准确性和稳定性。  相似文献