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1.
U. Santosuosso A. Papini 《International Journal of Environmental Science and Technology》2016,13(8):2037-2044
Geographic profiling is a method that proved to be useful also in order to investigate the point of origin of a biological invasion. K-means clustering and Voronoi diagrams can partition a data set of geographic positions of populations invading a defined area and are, therefore, useful in cases in which an invasion had more introduction events as points of origin. One critical point of the method is to identify the right number of clusters in which to divide the starting data set formed by groups of points on a map. The Silhouette method proved to be capable of identifying the best number of subsets (clusters) of the general set of observations by providing different values for different subdivisions of the set of observations in clusters. For each cluster, the corresponding Voronoi tessellation was built on the starting map. To test the method, we did a simulation of clusters of data (points) on a map and we verified whether the proposed methods worked efficiently with the simulated data set with hundred repeats and using a varying number of clusters on the same map. The used techniques revealed to be efficient in finding the highest probability area of the map that would include the starting points for each cluster. A case study consisted in a known data set, that is, the spreading pattern of Caulerpa racemosa var. cylindracea (sea grapes), that was compatible (highest probability) with an original point of introduction in southern Italy and long distance (thousands of kilometers) secondary spreads via anthropic dispersal. The proposed techniques may also be applied to other kinds of data sets of biological data distributed on a map or in general on a geometrical surface. 相似文献
2.
为了完善系统聚类分析算法理论,使之具有区分数据集非线性集群特征的能力,将核函数理论和系统聚类分析算法有机结合,推导出基于核函数理论的系统聚类分析方法。其基本思路是:把样本从低维观测空间非线性变换至高维像空间,使样本变得线性可分;然后,应用核函数理论“隐式”地实现高维像空间的系统聚类分析。用Pb、Bi、Mo质量浓度作为化探异常的分类依据,对8处化探异常进行分类实验研究,在Pb、Bi、Mo两两组合的二维平面图中,8处化探异常明显地分为（1, 3, 8）,（2, 4）和（5, 6, 7）3个点群,用核系统聚类方法能够很好地区分出这3个点群;而传统系统聚类方法却把8处化探异常错分成（1, 3, 8, 6）和（2, 4, 5, 7）两个类。由此可见,核系统聚类方法的类群区分能力高于传统系统聚类方法。 相似文献
3.
A Methodology for the Definition of Geotechnical Mine Sectors Based on Multivariate Cluster Analysis
Nazareth Ana Flávia Delbem Vidigal Lana Milene Sabino 《Geotechnical and Geological Engineering》2021,39(6):4405-4426
This paper offers a new method for the definition of geotechnical sectors in open pit mines based on multivariate cluster analysis. A geological-geotechnical data set of a manganese open pit mine was used to demonstrate the methodology. The data set consists of a survey of geological and geotechnical parameters of the rock mass, measured directly in several points of the mine, structured initially in twenty-eight variables. After the preprocessing of the data set, the clustering technique was applied using the k-Prototype algorithm. The squared Euclidean distance was used to quantify the proximity between numerical variables, and the Jaccard's coefficient of similarity was used to quantify the proximity between the nominal variables. The different cluster results obtained were validated by the multivariate analysis of variance. The identification of cluster structures was achieved by plotting them on the mine map for spatial visualization and definition of geotechnical sectors. These sectors are spatially contiguous and relatively homogeneous regarding their geological–geotechnical properties, indicated by a high density of points of the same group. It was possible to observe a great adherence of the proposed sectors to the mine geology, demonstrating the practical representativeness of the clustering results and the proposed sectors.
相似文献4.
Interpretation of regional scale, multivariate geochemical data is aided by a statistical technique called “clustering.” We investigate a particular clustering procedure by applying it to geochemical data collected in the State of Colorado, United States of America. The clustering procedure partitions the field samples for the entire survey area into two clusters. The field samples in each cluster are partitioned again to create two subclusters, and so on. This manual procedure generates a hierarchy of clusters, and the different levels of the hierarchy show geochemical and geological processes occurring at different spatial scales. Although there are many different clustering methods, we use Bayesian finite mixture modeling with two probability distributions, which yields two clusters. The model parameters are estimated with Hamiltonian Monte Carlo sampling of the posterior probability density function, which usually has multiple modes. Each mode has its own set of model parameters; each set is checked to ensure that it is consistent both with the data and with independent geologic knowledge. The set of model parameters that is most consistent with the independent geologic knowledge is selected for detailed interpretation and partitioning of the field samples. 相似文献
5.
在现存地下水监测网站中,观测站点分布的任意性、随意性和层次不清以及观测数据的冗余性等问题普遍存在,应用空间聚类原理,对所选研究区域廊坊地下水的监测点位及监测指标分别进行了空间聚类分析,对原始数据和经聚类处理后的数据分别进行了空间变异性评价,结果显示空间聚类分析是有效合理的。试图将空间变异性和空间聚类方法结合起来,为环境监测点的重新布置提供了理论依据,使提高监测效率与监测点的代表性、优化监测网格成为了可能;了解监测指标及监测点位在空间上的相关程度,为环境监测指标的确定提供理论依据,进而为环境管理、污染物控制以及环境资源的综合利用提供基础依据。 相似文献
6.
This paper presents an efficient Bayesian back-analysis procedure for braced excavations using wall deflection data at multiple points. Response surfaces obtained from finite element analyses are adopted to efficiently evaluate the wall responses. Deflection data for 49 wall sections from 11 case histories are collected to characterize the model error of the finite element method for evaluating the deflections at various points. A braced excavation project in Hang Zhou, China is chosen to illustrate the effectiveness of the proposed procedure. The results indicate that the soil parameters could be updated more significantly for the updating that uses the deflection data at multiple points than that only uses the maximum deflection data. The predicted deflections from the updated parameters agree fairly well with the field observations. The main significance of the proposed procedure is that it improves the updating efficiency of the soil parameters without adding monitoring effort compared with the traditional method that uses the maximum deflection data. 相似文献
7.
《Journal of Structural Geology》1988,10(3):297-299
Based on the theory of dynamical cluster analysis, a procedure for separating heterogeneous sets of fault-slip data into homogeneous sub-sets is proposed, which enables the stress state associated with each sub-set to be determined separately within a data set. This procedure is suitable for any method of determining the principal stress axes using fault-slip data and runs on a micro-computer with graphical output. 相似文献
8.
Richard A. Park 《Mathematical Geosciences》1974,6(4):333-352
A multivariate analytical strategy is proposed for aiding the investigator in extracting maximum information from environmental data. Data are carefully coded and scaled and are tested for redundancy using R-mode cluster analysis. The samples are partitioned into environmental classes using Q-mode cluster analysis. Q-mode ordination facilitates interpretations, which usually can be verified by comparison with field relationships. Discriminant analysis serves as an identification procedure for extending the classification to unknown samples. The strategy is demonstrated by application to Cape Hatteras microorganism distributions and Devonian sedimentary facies. 相似文献
9.
Recent studies in the United States and other Pacific Rim countries have identified a new form of ethnic minority group clustering
within the residential mosaic—ethnoburbs. These are suburban in location, occupied by relatively high-income, predominantly
Asian, immigrants, and low density in their nature: many migrants move directly to those suburbs rather than the inter-generational
outward migration from central city clusters typical of other migrant streams. Although ethnoburb residents tend to cluster
in particular segments of the built-up area they do not to form large percentages of the population there. As yet, no methodology
has been developed to identify these clusters, as a prelude to identifying their characteristics. This paper offers such a
procedure, based on local statistical analysis. It is applied to six Asian groups in Auckland, New Zealand. 相似文献
10.
Three discriminant function models are raised and cross-compared in order to distinguish geochemical patterns characteristic
for the Drava River floodplain sediments. Based on data representing total element concentrations in samples collected from
alluvium (A), terrace (T), and unconsolidated bedrock (B) at the border of a floodplain, four element clusters emerged accounting
for discrimination between the referred groups of sediments. The most prominent is contaminant/carbonate cluster characteristic
for alluvium. The other two are: silicate cluster typical for unconsolidated geological substrate (Neogene sedimentary rocks);
and naturally dispersed heavy metal cluster separating terrace from the former two groups. Models introducing depth intervals
and single profiles as grouping criteria reveal identical sediment-heavy metal matrices. The second important issue of this
paper is possibility of reclassification of samples originally assigned to one of the a priori defined groups of sediments,
based on established geochemical pattern. The mapped geological units can be reconsidered by the post hoc assignments to a
different group if geological border between alluvium and terrace or between terrace and bedrock can not be established geologically
with absolute certainty. 相似文献
11.
针对阶跃型滑坡阶跃点识别和预测难的问题,提出了一种基于聚类分析和集成学习的阶跃型滑坡阶跃点识别和判别模型。以三峡库区八字门滑坡ZG110钻孔2010年4月至2016年12月80个滑坡位移、库水位和降雨数据为例,通过聚类分析方法识别滑坡累积位移-时间曲线中的阶跃点和平稳点,并利用K均值聚类分析检验分类结果的准确性。基于灰色关联确定了滑坡位移的最佳诱发因素,结合随机森林模型建立阶跃型滑坡阶跃点判别模型并利用八字门滑坡ZG111钻孔验证该模型的准确性。模型阶跃点和平稳点的识别准确率均达90%以上,表明该方法在阶跃型滑坡识别中具有较好的适用性,可为阶跃型滑坡的预测提供参考。 相似文献
12.
A.J. Sinclair 《Journal of Geochemical Exploration》1974,3(2):129-149
A method of choosing threshold values between anomalous and background geochemical data, based on partitioning a cumulative probability plot of the data is described. The procedure is somewhat arbitrary but provides a fundamental grouping of data values. Several practical examples of real data sets that range in complexity from a single population to four populations are discussed in detail to illustrate the procedure.The method is not restricted to the choice of thresholds between anomalous and background populations but is much more general in nature. It can be applied to any polymodal distribution containing adequate values and populations with appropriate density distribution. As a rule such distributions for geochemical data closely approach a lognormal model. Two examples of the more general application of the method are described. 相似文献
13.
In this study, Bouguer gravity and aeromagnetic data have been used to better understand the geology and mineral resources near the late Carboniferous-late Permian porphyry Cu-Mo polymetallic mineralization in the Chinese Eastern Tianshan belt, which is extensively covered by Gobi-desert. The reduced-to-pole (RTP) transformation of regional-scale aeromagnetic data shows that the porphyry Cu-Mo deposit is within a cluster of magnetic anomaly highs that overprint on a northeast trending magnetic gradient belt generally along the crustal-scale Kanguertag-Huangshan fault. The 10 km upward continuation transformation of both Bouguer gravity and aeromagnetic data indicates that the known porphyry Cu-Mo polymetallic deposits are located on the flanks of prominent gravity and magnetic anomaly highs. These anomalies are spatially correlated with the late Carboniferous-late Permian igneous rocks and in the Tuwu-Yandong mineralization district are centered over the granodiorite rocks genetically related to porphyry copper systems. In order to minimize interpretational ambiguities, a useful approach that is correlation analysis (CA) based on correlation coefficient (CC) given by gravity and magnetic data was employed to separate positively and negatively correlated anomalies features. The CA procedure is applied to 10 km upward continuation transformation of both Bouguer gravity and RTP transformed aeromagnetic data for mapping correlative magnetization and density contrast anomalies from deep sources, which may be associated with the porphyry Cu-Mo polymetallic mineralization. Five prominent CC positive anomalies have been found in the southern margin of Dananhu-Tousuquan arc. Those anomalies zones could be interpreted to reflect a late Carboniferous-late Permian magmatic belt that is favorable for additional discoveries of late Carboniferous to late Permian porphyry copper systems in north region of Eastern Tianshan. 相似文献
14.
A. M. Shurygin 《Mathematical Geology》1993,25(7):759-772
The model of the Poisson point process is too vague for earthquake locations in space and time: earthquakes tend to cluster in middle distances and to repulse in large ones. The Poisson point model with variable density makes it possible to describe the tendency for clustering but does not reveal the periodicity of clusters. The author proposes the point-process model where locations of points are determined not by densities of point distribution, but by densities of interpoint differences distribution. In the model, a latent periodicity is revealed and used for prediction of a point process. In 1983, the point-process model prediction was made for the Kuril Islands for 1983–1987 and two signs of danger in time and location were determined. Then they were confirmed by strong earth-quakes. In 1989, a similar prediction was made for North Armenia. The Spitak earthquake in 1988 is clearly seen from the data of previous earthquakes. 相似文献
15.
Summary The analysis of data collected on rock discontinuities often requires that the data be separated into joint sets or groups.
A statistical tool that facilitates the automatic identification of groups of clusters of observations in a data set is cluster
analysis. The fuzzy K-means cluster technique has been successfully applied to the analysis of joint survey data. As is the case with all clustering
algorithms, the results of an analysis performed with the fuzzy K-means algorithm for discontinuity data are highly dependent on the distance metric employed in the analysis. This paper explores
the significant issues surrounding the choice and use of various distance measures for clustering joint survey data. It also
proposes an analogue of the Mahalanobis distance norm (used for data in Euclidean space) for clustering spherical data. Sample
applications showing the greater flexibility and power of the new distance measure over the originally proposed distance metric
for spherical data are given in the paper. 相似文献
16.
An extensive multivariate analysis procedure for prediction of blast fragmentation distribution is presented. Several blasts performed in various mines and rock formations in the world are brought together and evaluated. Blast design parameters, the modulus of elasticity, in situ block size are considered to perform multivariate analysis. The hierarchical cluster analysis is used to separate the blasts data into different groups of similarity. Group memberships were checked by the discriminant analysis. The multivariate regression analysis was applied to develop prediction equations for the estimation of the mean particle size of muckpiles. Two different prediction equations were developed based on the rock stiffness. Validation of the proposed equations on various mines is presented and the capability of the prediction equations was compared with one of the most applied fragmentation distribution models appearing in the blasting literature. Prediction capability of the proposed models was found to be strong. Diversity of the blasts data used is one of the most important aspects of the developed models. The models are not complex and suitable for practical use at mines. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
利用Excel实现R型聚类分析 总被引：2，自引：0，他引：2
R型聚类分析是对若干个元素进行数量化相似程度分类的一种数理统计方法，主要步骤包括：原始数据转换；求解相关系数；对结果聚类。利用Excel的数据分析工具实现R型聚类分析的方法和步骤，对野外一线地质人员的工作相当适用。 相似文献
18.
V. M. Danilov 《Astronomy Reports》2006,50(5):346-357
A model for a uniform, gravitating, ellipsoidal star cluster moving in a circular orbit around the Galactic center is considered. Three independent isolated integrals of stellar motion are written for this model. The characteristic features of the motion of a cluster star according to these three integrals are analyzed. Retrograde stellar motions dominate at the periphery of the model cluster, and the distribution of the stellar velocities is elongated along the direction of the cluster motion. A phase-space density function that depends on two of the integrals of motion is constructed. The distribution of the stellar velocities is constructed for the case of a three-integral phase-space density. Possible applications of the results are discussed. 相似文献
19.
Scott Painter 《Mathematical Geology》1998,30(2):163-179
Stochastic simulations of subsurface heterogeneity require accurate statistical models for spatial fluctuations. Incremental values in subsurface properties were shown previously to be approximated accurately by Levy distributions in the center and in the start of the tails of the distribution. New simulation methods utilizing these observations have been developed. Multivariate Levy distributions are used to model the multipoint joint probability density. Explicit bounds on the simulated variables prevent nonphysical extreme values and introduce a cutoff in the tails of the distribution of increments. Long-range spatial dependence is introduced through off-diagonal terms in the Levy association matrix, which is decomposed to yield a maximum likelihood type estimate at unobserved locations. This procedure reduces to a known interpolation formula developed for Gaussian fractal fields in the situation of two control points. The conditional density is not univariate Levy and is not available in closed form, but can be constructed numerically. Sequential simulation algorithms utilizing the numerically constructed conditional density successfully reproduce the desired statistical properties in simulations. 相似文献
20.
Danilo R. Velis 《Mathematical Geology》2007,39(4):409-417
Stationary segments in well log sequences can be automatically detected by searching for change points in the data. These
change points, which correspond to abrupt changes in the statistical nature of the underlying process, can be identified by
analysing the probability density functions of two adjacent sub-samples as they move along the data sequence. A statistical
test is used to set a significance level of the probability that the two distributions are the same, thus providing a means
to decide how many segments comprise the data by keeping those change points that yield low probabilities. Data from the Ocean
Drilling Program were analysed, where a high correlation between the available core-log lithology interpretation and the statistical
segmentation was observed. Results show that the proposed algorithm can be used as an auxiliary tool in the analysis and interpretation
of geophysical log data for the identification of lithology units and sequences. 相似文献