基于Kohonen网络的点群综合研究     

蔡永香  郭庆胜 《武汉大学学报(信息科学版)》2007,32(7):626-629

基于Kohonen网络模型，对标准的SOM（self-organizing feature map）算法进行了改进，在保持点群原有空间分布特征的情况下研究点群的选取和典型化。实践表明，该方法适合任意空间分布类型的点群综合。  相似文献   

GIS空间目标的广义Hausdorff距离模型   总被引：4，自引：0，他引：4  

邓敏  钮沭联  李志林 《武汉大学学报(信息科学版)》2007,32(7):641-645

分析了GIS中常用的空间距离度量及其存在的问题，这些距离度量没有顾及空间目标的整体形状、位置分布等特征。基于此，引入了Hausdorff距离的概念，给出了Hausdorff距离的计算方法，分析指出了Hausdorff距离容易受空间目标局部几何形状的影响。进而从统计学的角度分析了现有的距离度量并不能有效地表达空间目标间距离的整体分布，并提出了一种广义Hausdorff距离模型，这种距离模型能够度量空间目标间距离分布的中心趋势和离散度。实际算例证明了此模型在GIS环境下的实现方法。  相似文献   

空间数据模糊聚类的有效性评价     

胡春春  孟令奎  谢文君  周新忠 《武汉大学学报(信息科学版)》2007,32(8):740-743

基于模糊划分中存在的分类不确定性因素和空间数据的空间位置特征,提出了一种新的空间数据模糊聚类有效性函数。实验结果表明,这种新的有效性函数能够对模糊聚类结果的有效性进行正确的评价,特别是对于空间数据模糊聚类有效性评价,其分类效果较理想,同其他有效性指标相比,能得到较优的分类数。  相似文献   

融合形状和光谱的高空间分辨率遥感影像分类   总被引：13，自引：0，他引：13  

黄昕  张良培  李平湘 《遥感学报》2007,11(2):193-200

提出了一种像元形状指数及基于形状和光谱特征融合的高（空间）分辨率遥感影像分类方法。形状和光谱是遥感影像纹理的具体表现形式,尤其在高分辨率影像中地物细节得到充分表达,相邻像元的关系及其共同表征的形状特性成为分类的重要因素。本文用像元及其邻域的关系来描述其空间结构,同时为了更全面地利用影像特征,提出了基于支持向量机的形状和光谱融合分类方法。实验证明,该方法计算简便且能有效表达高分辨率影像的地物特征,提高分类精度。  相似文献   

道路网示意性地图的渐进式综合研究     

董卫华  郭庆胜  刘纪平  吕秀琴 《武汉大学学报(信息科学版)》2007,32(9):829-832,837

研究并总结了示意性道路网地图的制图规则,量化了约束条件,提出了一种道路网渐进式图形简化方法和移位方法,并研究了拓扑关系检查方法。在具体实验中,通过对道路网上点的分类,依据约束条件,快速生成有效的道路网示意性地图,同时保证了原始道路图与示意性道路图之间的拓扑关系一致性。  相似文献   

空间信息服务时态数据的管理与应用     

王亮  赵荣  李玉祥  范荣双 《测绘科学》2007,32(Z1):22-24

本文面向当前空间信息应用的实际需求,以传统GIS为基础,研究建立实用的、易于实现的集矢量与栅格数据为一体的时空数据模型,增加GIS对时态属性的管理和操作。本文研究解决了时态拓扑构建的关键技术,采用面向对象方法开发了一套时态空间数据库管理系统,实现了时空数据的采集、存储、查询和显示,并以中国多个历史时期的行政界线为基础数据,进行了时空数据模型的应用研究,为TGIS发展探索了一条实用的技术路线。  相似文献   

江汉平原粮食产量空间格局分析   总被引：1，自引：0，他引：1  

余晓敏  李强  张娜 《测绘地理信息》2020,(2):41-44,126

基于湖北省第一次地理国情普查数据、基础地理信息数据和统计年鉴等资料,采用洛伦兹曲线、Moran指数等对江汉平原典型4个粮食主产区监利县、洪湖市、仙桃市、潜江市的粮食产量空间格局进行了分析和研究。研究表明:①洪湖市耕地资源与粮食产量间的对应关系较为平等,粮食单产稳定,粮食生产空间聚集显著;②监利县、潜江市与仙桃市的耕地、粮食产量表现出极弱空间相关性或无相关性,粮食生产能力相对较差,耕地资源及产量未表现出空间聚集优势。该结论可为农业部门制定农业生产计划和发展规划提供良好的数据支撑,为地理国情普查成果的应用提供借鉴。  相似文献   

Reliability analysis for bearing capacity of surface strip footing using fuzzy finite element method     

Rajarshi Pramanik  Dilip Kumar Baidya  Nirjhar Dhang 《Geomechanics and Geoengineering》2020,15(1):29-41

ABSTRACT

This paper presents the reliability analysis on the basis of the foundation failure against bearing capacity using the concept of fuzzy set theory. A surface strip footing is considered for the analysis and the bearing capacity is estimated using the conventional Finite Element Method (FEM). The spatial variability of the variables is taken into consideration to capture the physical randomness of the soil parameters for an isotropic field. A variation of the probability of failure (P_f) against a varying limiting applied pressure (q) is presented for different Coefficient of Variation (COV) of the variables and different scale of fluctuation (θ). The results reveal that the friction angle of soil (?) is the most influencing parameter among the other variables. Further, the influence of the scale of fluctuation (θ) on the probability of failure (P_f) is also examined. It is observed that for a particular COV of ?, higher value of θ predicts higher P_f whereas, P_f increases as COV of ? increases for a particular θ value. Later, a comparison study is accomplished to verify the viability of the present method and it can be noticed that the present method compares well with the other reliability method (First Order Reliability Method) to a reasonably good extent.  相似文献   

Optical and near-infrared imaging of faint Gigahertz Peaked Spectrum sources     

I. A. G. Snellen    R. T. Schilizzi    M. N. Bremer    A. G. de Bruyn    G. K. Miley    H. J. A. Ro¨ttgering    R. G. McMahon  & I. Pérez Fournon 《Monthly notices of the Royal Astronomical Society》1998,301(4):985-1000

A sample of 47 faint Gigahertz Peaked Spectrum (GPS) radio sources selected from the Westerbork Northern Sky Survey (WENSS) has been imaged in the optical and near-infrared, resulting in an identification fraction of 87 per cent. The R  −  I R  −  K colours of the faint optical counterparts are as expected for passively evolving elliptical galaxies, assuming that they follow the R -band Hubble diagram as determined for radio-bright GPS galaxies. We find evidence that the radio spectral properties of the GPS quasars are different from those of GPS galaxies. The observed distribution of radio spectral peak frequencies for GPS sources optically identified with bright stellar objects (presumably quasars) is shifted compared with GPS sources identified with faint or extended optical objects (presumably galaxies), in the sense that a GPS quasar is likely to have a higher peak frequency than a GPS galaxy. This means that the true peak frequency distribution is different for the GPS galaxies and quasars, because the sample selection effects are independent of optical identification. The correlation between peak frequency and redshift that has been suggested for bright sources has not been found in this sample; no correlation exists between R magnitude (and therefore redshift) and peak frequency for the GPS galaxies. We therefore believe that the claimed correlation is actually caused by the dependence of the peak frequency on optical host, because the GPS galaxies are generally at lower redshifts than the quasars. The difference in the peak frequency distributions of the GPS galaxies and quasars is further evidence against the hypothesis that they form a single class of object.  相似文献   

Competition among destinations in spatial interaction models: a new point of view   总被引：1，自引：0，他引：1  

ＪｉｍＰｏｏｌｅｒ 《中国地理科学(英文版)》1998,8(3):212-224

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