Oceanic upwelling produced by northerly winds on the north Canterbury coast,New Zealand     

R. A. Heath 《新西兰海洋与淡水研究杂志》2013,47(3):343-351

The rates of upwelling calculated from the change in temperature distribution derived from two sets of hydrological stations (0.0107 cm.r^‐1) and the rate of upwelling calculated from the wind derived transport offshore for the period between the collection of the hydrological data (0.0086 cm.s^‐1) are found to be consistent.  相似文献   

基于EM聚类的X射线背散射图像违禁品分割方法     

王怀颖  陈力 《CT理论与应用研究》2013,(3):463-468

X射线康普顿背散射(CBS)技术是一项较新的射线安检技术,可以提高复杂背景下安检设备对爆炸物等有机违禁品的探测力度,这其中一个重要环节就是图像中有机违禁品的分割问题,本文分析了CBS技术成像图像的特点,有针对性地提出了一种基于EM聚类的图像中有机违禁品的图像分割方法,实验结果表明该方法具有很好的适用性。  相似文献   

基于机器学习的水位流量关系模型参数估计          下载免费PDF全文

江竹  宋文武 《水文》2013,33(1):74-78

为了克服经典水位流量关系模型在刻画河流动态变化特性时所存在的局限性,提出采用局部加权回归算法估计模型参数;为了提高参数估计精度以及流量的计算效率,提出一种聚类树加权回归方法.首先对训练样本进行聚类,然后使用k-最近邻方法将新的水位样本划分进最恰当的聚类中,最后估计河流日流量.该方法在估计过程中,避免了不相关信息的干扰,从而提高了日流量数据估计的效率和精度.利用某水文站的实测数据对方法进行测试,仿真结果表明,方法估计精度高,为水位流量关系模型参数估计提供了新的有效方法.  相似文献   

沂沭断裂带垂直形变的灰色关联分析应用研究     

朱成林  贾媛  李建奎  李杰 《地震研究》2013,36(2)

以一沂沭断裂带剖面水准测线为例,应用灰色关联分析方法研究了沂沭断裂带垂直剖面形变的空间分布特征.通过测点序列距离改化前后的关联度矩阵和关联序的差异研究垂直剖面的整体倾斜性变化特征,并研究了水准测线剖面形变时间上的时段性分布特征.实例表明灰色关联分析可以作为一种有实用价值的分析方法应用于断裂带垂直形变分析中.  相似文献   

由地震分布丛集性给出断层参数的一种新方法   总被引：5，自引：2，他引：3       下载免费PDF全文

王福昌  万永革  钱小仕  张丽娟  张梅东 《地球物理学报》2013,56(2):522-530

由于大范围内地质构造的复杂性和介质的非均匀性,发震断层面的几何形态一般十分复杂.如果大地震的破裂过程涉及多个断层的活动,则发震断层并非是单一断层平面,而是多个断层面的组合.利用地震空间位置分布丛集性,即震源点成丛位于断层面附近的假设,结合稳健扩充算法和主成分分析给出一种可以重构活断层网络三维空间结构的新方法.该方法每次从震源点集中处开始,利用假设检验扩充子断层面,并得到多个子断层面.接着按震源点属于最近断层面的准则把各子断层面内的震源点进行竞争,并根据一定假设合并和删除一些子断层面,最后用主成分分析确定每个子断层面参数.于是可根据地震事件目录给出一组矩形区域来描述断层面网络结构,其中每个矩形断层面由其位置、走向和倾角确定.通过计算机模拟发现,新方法可成功地重建模拟地震目录的断层面,最后用于南加州1992年6月28日发生的Landers地震部分余震目录中,得到各个子断层面参数与已知地质破裂或隐伏断层相当一致.  相似文献   

A canonical correlation approach to the determination of homogeneous regions for regional flood estimation of ungauged basins     

G. S. CAVADIAS  T. B. M. J. OUARDA  B. BOBÉE  C. GIRARD 《水文科学杂志》2013,58(4):499-512

Abstract

A canonical correlation method for determining the homogeneous regions used for estimating flood characteristics of ungauged basins is described. The method emphasizes graphical and quantitative analysis of relationships between the basin and flood variables before the data of the gauged basins are used for estimating the flood variables of the ungauged basin. The method can be used for both homogeneous regions, determined a priori by clustering algorithms in the space of the flood-related canonical variables, as well as for “regions of influence” or “neighbourhoods” centred on the point representing the estimated location of the ungauged basin in that space.  相似文献   

Disconnected Cartographies and Immappancy     

《The Cartographic journal》2013,50(4):291-296

Abstract

Manual shading, traditionally produced manually by specifically trained cartographers, is still considered superior to automatic methods, particularly for mountainous landscapes. However, manual shading is time-consuming and its results depend on the cartographer and as such difficult to replicate consistently. For this reason there is a need to create an automatic method to standardize its results. A crucial aspect of manual shading is the continuous change of light direction (azimuth) and angle (zenith) in order to better highlight discrete landforms. Automatic hillshading algorithms, widely available in many geographic information systems (GIS) applications, do not provide this feature. This may cause the resulting shaded relief to appear flat in some areas, particularly in areas where the light source is parallel to the mountain ridge. In this work we present a GIS tool to enhance the visual quality of hillshading. We developed a technique based on clustering aspect to provide a seamless change of lighting throughout the scene. We also provide tools to change the light zenith according to either elevation or slope. This way the cartographer has more room for customizing the shaded relief representation. Moreover, the method is completely automatic and this guarantees consistent and reproducible results. This method has been embedded into an ArcGIS toolbox.  相似文献   

面向土地用途分区的空间聚类系统设计与实现     

牛继强  谢瑾如  徐丰  蚩志锋 《测绘科学》2013,38(4):178-180

传统的土地用途分区方法存在受人为因素影响、效率低下的问题,不利于土地用途分区管制的实施,基于GIS的智能化的土地用途分区系统则可以弥补这一缺陷。本文以GIS相关理论和土地用途分区的需求分析为基础,构建了系统的逻辑框架,研究了数据库、模型库、算法库和知识库的设计方案,提出了土地用途分区过程中的空间数据整合、目标函数和分区模型的选择等问题的解决方案,并实现了面向土地用途分区的空间聚类系统。以典型地区的土地用途分区为例,验证了该空间聚类系统是一种智能、高效、科学的土地用途分区平台。  相似文献   

Spatial correlation description of deformation object based on fuzzy clustering and geological analysis     

Yin Hui 《地球空间信息科学学报》2013,16(3):69-72

The methods of deformation analysis and modeling at single point are realized easily now, but available approaches do not make full use of the information from monitoring points and can not reveal integrated deformation regularity of a deformable body. This paper presents a fuzzy clusetering method to analyze the correlative relations of multiple points in space, and then the spatial model for a practical dangerous rockmass in the area of Three Gorges, Yangtze River is established, in which the correlation of six points in space is analyzed by geological investigation and fuzzy set theory.  相似文献   

Mapping the porosity of international border to pedestrian traffic: a comparative data classification approach to a study of the border region in Austria,Italy, and Slovenia     

Nao Hisakawa  Piotr Jankowski  Gernot Paulus 《制图学和地理信息科学》2013,40(1):18-27

National borders play an important role in everyday life. Interest in border studies has increased with recent changes in geographical locations of the border or the fluctuation of the permeability of the border between some countries, such as in the European Union. Whether the nations are trying to increase traffic flow of the border or to implement stricter border control, having appropriate information of the border is crucial for effective policymaking.

The objective of this research was to identify areas of high porosity, or high permeability, for pedestrians along the southern national border region in Carinthia, Austria using terrain, land use, and road data along with geocomputational methods. Two unsupervised classification methods, the fuzzy K-means clustering and the Self-Organizing Map, were applied to segment the border into homogeneous zones according to topographic and infrastructural attributes. The fuzzy K-means clustering method was chosen for its ability to allow for a continuous approach to classification. With this method, an object can belong, with different degrees of membership, to multiple classes, which is a more realistic reflection of the natural world than discrete clustering, where each object can only belong to one class. However, the fuzzy K-means clustering method does have disadvantages, i.e. the user must determine the number of classes and the input parameters are required to be in continuous format. The second classification method, the Self-Organizing Map, is a type of artificial neural network and was chosen for its ability to automatically determine the number of classes and handle categorical data. The Self-Organizing Map is unique because it can transform high dimensional data into low dimensional display while preserving the topology and spatial distribution of the input parameters. The results of the two classification methods suggest that the fuzzy K-means classification is more effective than the Self-Organizing Map for this situation. However, more research is needed to determine the fit of these algorithms for particular spatial data classification tasks.

The results obtained from this research provide an insight into the permeability of the border region of Carinthia, Slovenia, and Italy to pedestrian traffic and can be potentially useful for decision making processes for tourism development and road transportation management in that region. Furthermore, the approach presented in this article can be applied to other national borders to identify zones permeable to pedestrian traffic.  相似文献