中国沙漠植物区系相似性的数值分析

应用Jaccard相似系数对中国沙漠植物区系进行了聚类分析。结果表明,可以将20个沙漠植物区系划归入蒙古沙漠植物区、西北沙漠植物区和华北沙漠植物区。根据科、属和种相似性系数的系统聚类结果,柴达木盆地、河西走廊、祁连山山前及腾格里沙漠边缘和吐-哈盆地相对较为孤立。区系相似性数值分析结果基本符合各地区植物区系存在的特点,与传统的典型植被划分结论相一致。     

Spatial Pattern and Order in Sunbelt Retailing: Shopping in Phoenix in the Twenty-First Century

Understanding the complexity of store location in sprawling polycentric cities requires exploitation of new spatial analysis methods that can decipher patterns in georeferenced point data. This article shows how the intrametropolitan location of retailing is best understood as a series of interconnected spatial distributions with varying order-based characteristics. A scattered pattern, which initially appears random or chaotic, is a web of differentiated spatial regimes containing wide-ranging order. A variety of clustering and colocation methods are used to uncover spatial patterns of retailing in Phoenix, Arizona. The analysis simultaneously identifies establishment associations and disassociations within and across sectors. Results show that clothing and motor vehicles are the most likely to cluster next to establishments in the same sector. These sectors also have strong intersectoral relationships across retailing. We find limited evidence that the size of establishments significantly increases with distance from sectoral mean centers. Geospatial technologies are increasingly used by individual retailers to locate and manage their facilities. It is important that scholarly analysis of retailing spatial patterns keeps pace, especially as cities grow and land use and land value patterns become more complex.     

河北南部及邻近地区中小地震震源机制特征分析

利用P波初动和振幅相结合的广义极性振幅技术法(GPAT),反演2007-2016年河北南部及邻近地区发生的368个ML≥2.0中小地震震源机制解,利用统计方法和系统聚类方法,分析震源机制解参数特征。结果表明,河北南部及邻区中小地震以走滑地震为主;正断层和逆断层相对较少,断层面以倾斜或直立为主,断层运动表现为左旋走滑和右旋走滑,应力作用以水平和近水平推扭方式为主。     

基于模糊聚类的声呐图像多区域分割

图像分割是图像识别中的主要问题,同时它又是一个经典难题;声呐图像恶劣的品质使图像的分割变得更为困难。文章将模糊聚类应用于声呐图像的多区域分割,实验证明这种方法简便而有效。     

基于星载SAR影像的苏北地区海岸线提取研究

介绍了K-means聚类分割法和形态学处理,并对比了几种边缘算子;针对Prewitt算子和Roberts算子在像素点邻近区域内受噪声影响较大、边缘检测效果不佳的问题,选用Canny算子提取海岸线.首先对SAR影像进行K-means算法、形态学处理,再采用Canny算子提取海岸线.与其他边缘提取算法相比,该方法提取的海岸...     

矢量居民地多边形多级图划分聚类方法

针对复杂居民地多边形的信息挖掘问题,提出了一种多级图划分聚类分析方法,构造居民地多边形的图模型,并通过对图模型进行粗化匹配与重构、初始化分和细化得到聚类结果.首先构建研究区域内居民地建筑物的Delaunay三角网,生成包含研究对象之间的邻接信息图;然后结合空间认知准则和人类认知的特点,采用形状狭长度、面积比、凹凸性、距...     

Seismic reliability assessment of lifeline networks using clustering‐based multi‐scale approach

Seismic reliability assessment of lifeline networks gives rise to various technical challenges, which are mostly caused by a large number of network components, complex network topology, and statistical dependence between component failures. For effective risk assessment and probabilistic inference based on post‐hazard observations, various non‐simulation‐based algorithms have been developed, including the selective recursive decomposition algorithm (S‐RDA). To facilitate the application of such an algorithm to large networks, a new multi‐scale approach is developed in this paper. Using spectral clustering algorithms, a network is first divided into an adequate number of clusters such that the number of inter‐cluster links is minimized while the number of the nodes in each cluster remains reasonably large. The connectivity around the identified clusters is represented by super‐links. The reduced size of the simplified network enables the S‐RDA algorithm to perform the network risk assessment efficiently. When the simplified network is still large even after a clustering, additional levels of clustering can be introduced to have a hierarchical modeling structure. The efficiency and effectiveness of the proposed multi‐scale approach are demonstrated successfully by numerical examples of a hypothetical network, a gas transmission pipeline network, and a water transmission network. Copyright © 2014 John Wiley & Sons, Ltd.     

利用小震震源机制解研究宁夏南部及邻区构造应力场

利用垂直向Pg和Sg波振幅比方法计算了2003年1月至2009年10月间宁夏南部及邻区的40个中小地震的震源机制解,然后对计算所得的40个地震的震源机制解进行系统聚类及应力场分析,利用格点尝试法研究灵武—吴忠地区(I区)和宁夏南部地区(II区)的平均震源机制解。结果表明:该区域主要受北东东向压应力作用而形成右旋走滑型断层,同时又带有张性分量;I区域构造应力场主压应力方向以水平作用为主,地震产生的震源区构造变形是北东向发生压缩,北西向发生相对扩张;II区域构造应力场主压应力方向以水平作用为主,地震产生的震源区构造变形是北东东向发生压缩,北北西向发生相对扩张。     

基于人工蜂群算法的岩体结构面多参数优势分组研究

岩体结构面优势分组是研究岩体力学性质与水力特性的基础,通常的分析方法是只根据产状进行划分。鉴于结构面其他特征对岩体力学性质的重要影响,考虑结构面倾向、倾角、迹长、张开度、表面形态5个特征参数,提出了基于人工蜂群算法的岩体结构面多参数优势分组方法。以样本总体离差平方和为目标函数,建立岩体结构面多参数优势分组的数学模型,应用人工蜂群优化算法求解,以目标函数值最小时的解作为聚类中心,并自动确定分组边界。对人工生成的结构面数据的计算结果验证了该方法的正确性,该方法的求解精度是令人满意的。最后,将该方法应用于怒江松塔水电站坝址区岩体结构面多参数优势组的划分,得到了较为合理的分组结果,进一步验证了此方法具有较高的运行效率与工程实用性。     

一种基于人工免疫网络聚类的入侵检测方法

提出了一种基于自适应半径免疫算法(ARIA)的入侵检测方法.ARIA训练得到的抗体网络充分保留了原始数据的密度分布信息,具有准确的空间形态;再用最小生成树算法和zahn划分标准对抗体网络细胞聚类,聚类得到的簇被标记为正常或异常并用于网络异常检测中.对KDD CUP 99数据集的实验结果表明:相对于基于aiNet的入侵检测方法,新的算法检测率高、误报率低,能够有效识别KDD中的已知攻击和未知攻击.