综合线面特征分布的点目标多尺度聚类方法     

余莉  甘淑  袁希平  杨明龙 《测绘学报》2015,44(10):1152-1159

考虑空间数据分布的复杂性与不连续性,提出了一种点目标聚类方法。算法利用全要素Voronoi图准确识别与表达点目标与线面实体的空间相关性;根据点目标位置分布特征计算面积阈值来控制聚类的粒度,同时以空间尺度变化下面积阈值的恒定作为判断尺度收敛的条件,实现点目标的多尺度划分,时间复杂度为O(nlogn)。经试验验证,聚类尺度随点目标分布特征自适应收敛,算法无须自定义参数,能够有效地发现受线面目标约束的任意形态点目标集群,对异常值处理稳健。  相似文献   

改进的加权Voronoi图ArcGIS矢量生成算法     

田松  崔希民  孙云华  宫宇 《测绘科学》2015,(8):82-86

加权Voronoi图是根据生成元权重划分空间的方法,广泛应用于地学领域。针对传统加权Voronoi图ArcGIS矢量生成算法不能处理重叠点、复杂多边形及更新操作等问题,该文提出了一种改进算法,结合C#和ArcEngine,利用增量法思想,通过重叠点处理、区域分割合并、加权区域重分类、加权区域重划分等方法实现,可嵌入ArcGIS应用软件使用或独立运行,具有良好的可用性,精度高,便于数据库存储管理,扩展了加权Voronoi图在地学领域的应用。  相似文献   

一种基于Voronoi图的人防警报器空间选址算法     

王峰  王惠  赵耀强  夏飞 《测绘软科学研究》2012,(2):81-84

首先通过声学传播原理研究了警报器覆盖范嗣模型。结合Voronoi图影像范围、最大空心圆策略和平面完全刮分等特性,提出了基于Voronoi图的警报器空间选址算法。文章详细阐述了算法基本思想和流程,最后进行了算法组件设计和系统开发实践。实践表明采用该算法能满足城市警报器合理选址和适当重叠覆盖的要求,并具有其优越性。  相似文献   

利用Voronoi图的城乡居民点布局优化研究   总被引：4，自引：0，他引：4  

覃瑜  师学义 《测绘科学》2012,(1):136-138,150

本文综合考虑居民点现状布局及相邻居民点间相互影响,以山西省晋城市为例,应用Voronoi图理论,依据熵值、聚类指数、标准差3个测度组合,将晋城市居民点划分为4种整理类型并绘制城乡用地布局等级图,结合2020年晋城市居民点用地规模预测值,进行晋城市居民点布局优化。结果显示,考虑居民点布局现状,利用Voronoi图理论及其聚合形态测度检验,为城乡居民点布局优化方案的提出提供了空间理论依据,是布局优化的直观方法。  相似文献   

A NUMERICAL EXPERIMENT STUDY ON THE FORMING MECHANISMS OF LOW-LATITUDE CIRCULATION CELLS AND PRECIPITATION DURING AN EAST ASIAN COLD SURGE          下载免费PDF全文

Zhu Qiangen  Yu Bin 《Acta Meteorologica Sinica》1994,8(4):419-430

The forming mechanisms of low-latitude circulation cells and precipitation during an East Asian cold surge have been studied by using a five-layer primitive equation model.Numerical experiments show that in mid-high latitudes,the propagation of the East Asian winter monsoon is nearly a dry process;in low-latitudes,the effects of cumulus convection intensify the northeast monsoon and northeast trade wind;however,they also prevent the intertropical convergence zone(ITCZ) from further southward invasion,and strengthen the meridional and zonal cells over East Asia. Numerical results also indicate that the winter monsoon precipitation in Indonesia and Northern Australia can exist independently.Both the South China Sea(SCS) cold surge and the West Pacific northeast cross-equatorial trade wind are of importance for the formation of the Northern Australia summer monsoon and its precipitation.Numerical results show that the development of cumulus convection,triggered by the SCS cold surge,is a crucial factor in forming the heavy monsoon precipitation and low-level stationary disturbances in Indonesia and Borneo.The tropical topography and northeast trade wind disturbances only affect the intensity of precipitation there.  相似文献   

Seasonal variation in abundance and species composition of a planktonic diatom assemblage including viable cells on the bottom in matsushima bay,northeastern japan     

ICHINOMIYA Mutsuo  TANIGUCHI Akira 《中国海洋大学学报(英文版)》2003,2(2):160-166

Seasonal variation in abundance and species composition of a planktonic diatom assemblage distributed in the water column and also settled on the bottom was investigated for the shallow coastal water in Matsushima Bay on the Pacific coast of northeastern Japan during the period from October 1999 to September 2000. A spring bloom of diatoms began in April when nutrient concentrations started to increase, indicating the importance of nutrients. Viable cells of Skeletonema costatum and Thalassiosira spp., which were the dominant species in the water column throughout the year, were also always abundant in the bottom sediment. Both populations in the water column and on the bottom fluctuated essentially in parallel. For the planktonic diatoms in shallow coastal waters to maintain their vegetative populations in the water column, it would be advantageous for them to have a seeding population of viable cells on the bottom that are easily resuspended into the upper photic layer.  相似文献   

Delaunay三角网与Voronoi图在划分城市影响空间中的应用研究   总被引：4，自引：0，他引：4  

闫卫阳  郭庆胜  李圣权 《测绘信息与工程》2004,29(3):1-3

探讨了基于Delaunay三角网和加权Voronoi图划分城市影响空间的方法,论证了其合理性和可行性,并对两种方法进行了对比分析,最后以河南省为例进行了实证分析.  相似文献   

基于动态Voronoi图的距离倒数加权法的改进研究   总被引：2，自引：0，他引：2  

颜辉武  祝国瑞  徐智勇 《武汉大学学报(信息科学版)》2004,29(11):1017-1020

针对距离倒数加权法的不足 ,采用动态Voronoi图选取待插值点的邻近点 ,对每个已知数据点增加反映该点梯度的增量 ,并建立已知数据点的ε邻域避免计算误差 ,以改进距离倒数加权法 ,为距离倒数加权法的广泛应用创造条件。通过交叉检验与实际应用 ,证实利用改进后的距离倒数加权法进行空间数据插值精度更高 ,效果更为理想  相似文献   

电子地图中居民地的多尺度显示     

宋国民贾奋励  王光霞 《测绘学院学报》2004,21(1):57-60

探讨了多尺度的含义，并将居民地多尺度表达的研究限定在详细程度的变化上；阐述了电子地图中居民地多尺度表达的基本原理，即在保持原图的分布特征和疏密对比的情况下按照居民地自身的分类分级和重要性程度进行一定数量的取舍；建立了居民地多尺度显示的模型，根据此模型提出了采用二级邻近点判别法结合Voronoi图进行居民地要素的显示等级设置的方法，并进行了相应的实验，结果表明该方法对居民地的分布特征、密度对比和延伸方向均能较好的保持。  相似文献   

Study of the Interaction between Biological Cells of Different Shapes and Sizes and Electromagnetic Fields Produced by Natural Phenomena     

Diaz-Sandoval  Rosa  Mendoza  Blanca 《Natural Hazards》2004,31(1):143-156

We carry out a study of the interaction between electromagnetic fields produced innature and cells with no structure but with different shapes and sizes, considered asapproximations of those observed in the human body. Magnetic fields produced byvarious atmospheric and geomagnetic phenomena are compared with the fieldsgenerated by the cells themselves. Working with frequencies up to 10⁵ Hz, we found that in most cases lightning is the natural phenomena capable of producingfield intensities comparable to those generated by the cells. As a first approximationwe assume that a cell might be affected only if a field of intensity comparable to thecell's field is present. Oscillating fields of less intensity and their harmonics can involveresonant interactions with the cells, however this situation is not considered here. Under the approximation of our study we found that the size and the shape are parameters of paramount importance: lightning represents a natural hazard only for the largest cells, while the quadrangular cells are not affected by any of the natural phenomena considered here.  相似文献