A multivariate Bernstein copula model for permeability stochastic simulation

This paper introduces a general nonparametric method for joint stochastic simulation of petrophysical properties using the Bernstein copula. This method consists basically in generating stochastic simulations of a given petrophysical property (primary variable) modeling the underlying empirical dependence with other petrophysical properties (secondary variables) while reproducing the spatial dependence of the first one.This multivariate approach provides a very flexible tool to model the complex dependence relationships of petrophysical properties. It has several advantages over other traditional methods, since it is not restricted to the case of linear dependence among variables, it does not require the assumption of normality and/or existence of moments.In this paper this method is applied to simulate rock permeability using Vugular Porosity and Shear Wave Velocity (S-Waves) as covariates in a carbonate double-porosity formation at well log scale. Simulated permeability values show a high degree of accuracy compared to the actual values.     

2010年南方持续暴雨期大气环流异常及其低频特征研究

利用NCEP／NCAR逐日再分析资料以及国家气候中心台站降水资料等,应用多变量经验正交函数展开（MV—EOF）等方法,对2010年南方持续暴雨期大气环流异常及其低频特征进行了分析。结果表明：2010年东亚夏季风异常偏弱、西太平洋副热带高压位置异常偏南、三次季风涌的出现和高空急流与散度场活动异常及其相互配合,是南方降水异常的主要影响系统;对风场和降水场MV-EOF空间型分布的分析显示,低频降水中心与200hPa的气流辐散中心和850hPa辐合中心相关联;降水的第一模态反映了东亚夏季风的气候态演变,第二、三模态反映了夏季风在季节性推进过程中不同尺度的低频振荡,7月前半月和6月中下旬,第二、三模态分别处于低频振荡的正位相,使长江中下游梅雨和华南前汛期延迟结束,并且增强了江南的梅雨降水,夏季风的气候态演变和低频振荡相叠加导致2010年我国南方暴雨频发。     

Environmental controls on the development of Mississippian microbial carbonate mounds and platform limestones in southern Montagne Noire (France)

Late Mississippian carbonates in southern Montagne Noire are dominantly domical to laterally‐accreted microbial mounds in some formations, as well as stratiform microbial limestones occurring in hundreds of olistoliths within a flysch basin, constituting pieces of a giant puzzle that are used to help reconstruct a platform in a region that is no longer preserved. Petrographic data of limestone samples from 14 continuous long sections of olistoliths have been analyzed statistically, using multivariate clustering (Q‐mode) of the components/matrix/cement and canonical correspondence analysis that allow the reconstruction of the environmental parameters of carbonate microbial communities in space and time. Clustering analysis separated microbial and non‐microbial facies. The calculation of indices along the various axes from canonical correspondence analysis allows recognition of the controlling factors of the mounds and microbial growth as being turbidity, light penetration, bathymetry and storms. Turbidity and light penetration are the primary factors controlling the morphology of the microbial limestones. Representation of the light penetration and bathymetry indices on the stratigraphical sections defines two vertical environmental gradients. Light penetration can be subdivided into euphotic, euphotic–dysphotic and dysphotic‐aphotic conditions. The representation of the bathymetry allows the subdivision of samples into a deeper outer ramp, external mid‐ramp and internal mid‐ramp. The curve distance from the section base = f (index) suggests a cyclicity for the platform that cannot be compared with the onlap curve defined from other cratonic areas (Moscow Basin), and thus the cyclic succession of the Montagne Noire is interpreted to have been mostly tectonically‐controlled. Integration of the data allowed the reconstruction of the original Mississippian carbonate platform, where, up to the Mikhailovian, it appears to correspond to a platform morphology, with narrow shallow water facies and wide turbiditic systems, whereas the width of shallow‐water settings expanded during the Venevian to the Protvian, forming a ramp or distally‐steepened ramp with widespread microbial limestones.     

Object-Oriented Island Land Cover Change Detection by Iteratively Reweighted Multivariate Statistical Analysis

ABSTRACT

In studies of changes in island geographic information, a key topic is island land cover change detection using multitemporal remote sensing images; such information can provide good reference for island exploitation, marine resource conservation, marine economic development, and national defense building. This study proposes a fast and easy-to-implement algorithm of object-oriented change detection based on iteratively reweighted multivariate statistical analysis with high-resolution remote sensing images and vector data, improving effects of normal multivariate alternative detection by combining object-oriented technology with probability density function of chi-square distribution. This method builds vectors in feature space with spectral, texture, and spatial structure information of objects segmented based on boundaries and categories of features in vector data. By feature optimization and iterative extension to multivariate statistical analysis for change detection, change regions can be extracted. Experiments on Zhaoshu Island area show that the proposed method is highly effective and accurate in detection of change regions.     

Reliability assessment of ultimate limit state of twin caverns

Construction of a cavern in close proximity to an existing cavern modifies the state of stresses and movements in a zone around the existing cavern, as some degree of interaction between these two caverns generally takes place. This study investigates the interaction of two parallel caverns and the influence of such interaction on stress-induced global stability in terms of a global factor of safety. A series of finite difference analyses were performed to derive the global factor of safety of a system of two parallel and adjacent caverns. A mathematical response surface model was then built using the multivariate adaptive regression splines (MARS) approach and a series of charts based on this surrogate model were developed to relate the global factor of safety to the critical parameters. The built MARS model is of high accuracy and is simple to interpret and can be used to perform probabilistic assessment of ultimate limit state of twin caverns.     

基于典型饱水砂岩样品的多维空间多元统计密度反演方法

实测数据资料、岩石物理学和多维空间多元统计思想的结合,有助于定量解析数据,减少岩石骨架、流体信息预测的风险性。运用典型饱水砂岩样品(韩德华G组砂岩样品)的密度、黏土含量和孔隙度实测数据,反演石英、黏土和流体的密度,所得反演结果符合实际情况,得到的拟合密度与实测密度相关系数可达0.985 5。所提出的密度反演方法的核心是多维空间多元统计思想与质量守恒定律相结合;与传统二维空间二元回归的密度反演方法对比结果表明,该方法不仅可以避免回归运算中奇异点的影响,而且得到的拟合密度与实测密度呈更为显著的相关关系。反演结果的均值与实际值相对误差在2%左右,准确度高,证明了方法的合理有效性。     

Multivariate Correlation in the Framework of Support and Spatial Scales of Variability

This paper extends the concept of dispersion variance to the multivariate case where the change of support affects dispersion covariances and the matrix of correlation between attributes. This leads to a concept of correlation between attributes as a function of sample supports and size of the physical domain. Decomposition of dispersion covariances into the spatial scales of variability provides a tool for computing the contribution to variability from different spatial components. Coregionalized dispersion covariances and elementary dispersion variances are defined for each multivariate spatial scale of variability. This allows the computation of dispersion covariances and correlation between attributes without integrating the cross-variograms. A correlation matrix, for a second-order stationary field with point support and infinite domain, converges toward constant correlation coefficients. The regionalized correlation coefficients for each spatial scale of variability, and the cases where the intrinsic correlation hypothesis holds are found independent of support and size of domain. This approach opens possibilities for multivariate geostatistics with data taken at different support. Two numerical examples from soil textural data demonstrate the change of correlation matrix with the size of the domain. In general, correlation between attributes is extended from the classic Pearson correlation coefficient based on independent samples to a most general approach for dependent samples taken with different support in a limited domain.     

Patterns and Levels of Organochlorines (DDTs, PCBs, non-ortho PCBs and PCDD/Fs) in Male Harbour Porpoises (Phocoena phocoena) from the Baltic Sea, the Kattegat-Skagerrak Seas and the West Coast of Norway

Patterns and levels of chlorinated aromatic contaminants (DDTs, PCBs, non-ortho PCBs and PCDD/Fs) in blubber tissue were compared among six sample groups of male harbour porpoises (Phocoena phocoena) from the Baltic Sea, the Kattegat-Skagerrak Seas and the west coast of Norway. A principal component and classification analysis showed that mature harbour porpoises from the Baltic had significantly different contaminant patterns than animals from the Kattegat-Skagerrak and Norway. ANOVAs showed that mature porpoises from the Baltic had higher levels of ΣPCB and several individual PCBs and PCDD/Fs than the Kattegat-Skagerrak and the Norwegian samples and higher ΣDDT than the Norwegian. A comparison between immature porpoises showed that Baltic animals had higher levels of ΣPCDD/F than the corresponding sample from the Kattegat-Skagerrak. The levels of ΣDDT, ΣPCB and Σnon-ortho PCB were significantly higher in animals collected during 1978–81 compared to animals collected in 1988–90 indicating a temporal decline of these organochlorines in the Kattegat-Skagerrak Seas. The contaminant levels recorded in the Baltic Sea are a serious cause for concern and could have management implications for the already threatened harbour porpoises in this area.     

Early Benthic Organism Colonization on a Caribbean Coral Reef (Barbados, West Indies): a Plate Experimental Approach

Abstract. Macrofaunal colonization was studied using coral plates fixed at 10 m depth on a fringing reef in Barbados, West Indies. Two sites were compared: Spring Garden, a site that is affected by eutrophication, and Six Men's Bay which is relatively free of this effect. Two sets of plates were immersed in winter and spring 1990 at each site and monitored for 28 and 19 weeks, respectively. Green and brown algae colonized first, followed 2 weeks later by ostracods, cumaceans, amphipods and polychaetes: terebellids, nereidids and syllids. Most colonizers either nestled or encrusted. A total of 11 017 invertebrates belonging to 145 species were collected. Polychaetes were the most abundant and diverse zoological group. Considering polychaetes, crustaceans and molluscs, the study sites shared around 75% of the species. Overall, densities were higher on lower (shaded) surfaces while diversities were higher on upper (illuminated) sides. Similarity coefficients and correspondence analysis showed different macrobenthic assemblages and colonization patterns in light and shaded and in polluted and unpolluted sites. Coral plates were associated according to their 'immersion time' and were closely linked to their stage of development. Spring Garden (polluted) presented a higher number of soft-bottom and deposit-feeder species ( e.g. , Capitella capitata ).     

云南城市职能分类探讨

采用城市劳动力资料, 运用在城市经济基础研究之上的多变量聚类与统计分析相结合的方法, 根据最新统计资料, 首次对云南省全部城市进行了统一的综合职能分类, 共分出５个大类４ 个亚类, 分类结果对认识云南城市的职能结构和了解每一个城市的职能特点具有重要意义, 在方法上与实践中有广泛的认识价值和应用价值。