An application of cluster analysis in mineral exploration

This paper presents a technique for evaluating the similarity of ore deposits utilizing several geological variables. Information on tungsten mines in North America, taken from published literature, was used for a cluster analysis to group samples according to their similarity based on a simple matching coefficient. It was possible to interpret and evaluate different ore environments that clustered according to age, mineralogy, and other variables. Cluster analysis may be important in mineral exploration where considerable amounts of data are available for analysis. Subtle relationships that might be overlooked because the data are too voluminous can be isolated using this technique. It also can be used to establish exploration priority in unknown areas on the basis of similarity to known metallogenetic provinces.     

Maximum likelihood estimation of the mean parallax and kinematic parameters of the Pleiades

A simultaneous, maximum-likelihood determination of the distance and kinematic parameters of the Pleiades is made. The results are: distance of the cluster d = 135.56 ± 0.72 pc, dispersion σ_d = 7.66 ± 0.80 pc; space velocity V = 25.94 ± 0.13 km/s, dispersion σ_v = 0.58 ± 0.09 km/s coordinates of the convergent point A = 101.95° ± 0.47°, D = −41.36° ± 0.29°.     

The sampling distribution of theW statistic of disjunction for the arbitrary division of a random rectangular distribution

The sampling distribution of the Wstatistic of disjunction has been estimated by Monte Carlo simulation for the case where the underlying distribution is a random rectangular (Poisson) variable that is divided into two groups at an arbitrary position. A transformation to sinh ^–1 log _e Wgave a variable that was acceptably normal, and from this a simple approximation for the distribution is given, together with a diagram of confidence limits of Wfor this case.     

Preliminary assessment of a nonlinear mapping algorithm in a geological context

A new algorithm has been developed by J. W. Sammon for the nonlinear-point mapping of high-dimensional data in two dimensions such that the inherent structure of the data is approximately preserved. This paper describes results using several sets of geologic data including stratigraphic thickness, petrographic modal analysis, and morphological or geochemical measurements. Comparisons are made with hierarchical cluster analysis using dendrogram representation. Initial results are encouraging and suggest that the technique could have widespread geological applications.     

数字海图点群状特征的识别、量测与综合

空间分布特征的保持是点群自动综合的核心和难点所在,为此,本文定义了4个参量：分布范围、分布密度、分布中心和分布轴线,来描述点群目标的结构化信息。利用Delaunay三角网和Voronoi图两种模型,着重探讨了点群分布特征的识别和量测问题,并在识别与量测的基础上,通过Voronoi图的动态构建,给出了点群自动综合模型,通过实际岛群数据的检测,证明了模型的正确性与可行性。     

BUSINESS CLUSTERS IN THE SOUTH: A CRITICAL APPRAISAL FROM INDONESIAN EVIDENCE

Advocacy of the advantages accruing to business clusters in developing economies has followed that in developed economies. With doubts emerging about the evidence for these in developed economies, it is therefore appropriate to review the experience in the developing world. A model of cluster emergence and growth has guided accounts of developing country clusters. Drawing on experience from Indonesia, doubts are raised about that model's prediction of the emergence of successful joint action in maintaining cluster advantages. Any advantages from clustering are insufficient to face development challenges arising from the globalisation of economic activity. The significance of business clusters in low income economies needs to be reviewed in the light of actual experience and the reappraisal emerging in developed or high income countries.     

Interactive analysis of the spatial distribution of disease using a geographic information systems

Geographic information systems (GIS) provide a variety of tools for the manipulation and display of public health data. Few, however, enable users to interactively evaluate hypotheses on spatial trends in disease risk that may be suggested by maps of measures of disease impact. We addressed this limitation by developing a seamless interface between a commercial GIS and a suite of spatial analysis algorithms. Users of the system can utilize the GIS's capability to interactively select and manipulate geographically referenced data and, through a series of pull-down menus, apply a variety of exploratory analysis methods to this information. In the presented application, we illustrate this capability by including algorithms for the reduction of random noise in observed incidence rates, for the detection of unusual aggregations of disease events, and for the statistical evaluation of inferences drawn from spatial trends. We demonstrate this application by examining lung cancer mortality in the state of Ohio. Received: 22 September 1999 / Accepted: 8 March 2000     

Variation of shearwave splitting in earthquake clusters with very similar waveforms

IntroductionAfter the confirming of anisotropy theory and the shear wave splitting, Crampin suggested that the accumulation and release of stress before and after a large earthquake could be observed by investigating the behavior of shear-wave (Crampin, et al, 1984; Crampin, 1987). Since that time, seismologists tried to find evidence to prove the hypothesis. Peacock, et al (1988) and Crampin, et al (1990) declared that they find a variation of time delay before and after the North Palm Spr…     

波形极相似的地震丛集中剪切波分裂的变化

在1991年大同MS5.8地震余震的记录中,一些小地震丛集中可见波形极为相似的地震对,利用各对地震记录的互相关函数可以确认其相似性．为了辨认剪切波波形中发生的微小变化,采用重采样技术提高采样率．可以直接从地震图中观察到丛集中成对地震的剪切波分裂的变化．      

广西北海市地下水系统水化学特征的分析

对广西北海市近20年的地下水水质监测资料和2002-2003年野外实地取样的测试资料进行分析,并采用Piper图和Q型群分析进行水化学分类,结果表明该地区北部地下水以Ca·Na-HCO₃型为主,水化学特征显示地下水化学成分受降雨入渗和溶滤的影响,而南部地下水以Na-Cl或Na·Ca-Cl型为主。北海市天然条件下地下水的矿化度低,pH值低,呈偏酸性。低矿化度的雨水、可溶盐含量极低的含水介质、迅速的水循环以及长期的淋滤作用,导致了北海地区地下水低矿化度的特点。