Means and Covariance Functions for Geostatistical Compositional Data: an Axiomatic Approach

This work focuses on the characterization of the central tendency of a sample of compositional data. It provides new results about theoretical properties of means and covariance functions for compositional data, with an axiomatic perspective. Original results that shed new light on geostatistical modeling of compositional data are presented. As a first result, it is shown that the weighted arithmetic mean is the only central tendency characteristic satisfying a small set of axioms, namely continuity, reflexivity, and marginal stability. Moreover, this set of axioms also implies that the weights must be identical for all parts of the composition. This result has deep consequences for spatial multivariate covariance modeling of compositional data. In a geostatistical setting, it is shown as a second result that the proportional model of covariance functions (i.e., the product of a covariance matrix and a single correlation function) is the only model that provides identical kriging weights for all components of the compositional data. As a consequence of these two results, the proportional model of covariance function is the only covariance model compatible with reflexivity and marginal stability.     

Three-Dimensional Interpolation and Lithofacies Analysis of Granular Composition Data for Earthquake-Engineering Characterization of Shallow Soil

In Japan, many major cities are located on tectonic basins which are surrounded by faults and underlain by soft alluvial materials. Because these areas are subject to earthquake damages, it is important to determine their seismic engineering characteristics. Geotechnical databases which contain many borehole logs are useful information sources for this type of analysis. Each datum stored in the database has a value or an attribute, and its location is irregular in both horizontal and vertical directions. A new interpolation method based on the optimization principle is proposed here to deal with such three-dimensionally distributed data. Susceptibility of unconsolidated ground to liquefaction is known to be related to the content of loose and saturated sand. The mixture ratio of several soil types in a deposit, i.e., granular composition, is strongly influenced by the sedimentary environment. There are two numerical methods: the optimization principle method (OPM) used to determine three-dimensional distribution of granular composition and the model used to evaluate liquefaction. The application of the proposed methods to two locations in Japan indicated that the zones with high susceptibility to liquefaction were indeed those that had suffered from liquefaction during past earthquakes.     

土钉墙与轻型井点联合基坑支护降水技术应用

结合一个具体工程应用实例，介绍了土钉墙与轻型井点联合基坑支护降水技术的设计方法，并初步总结了该技术的主要特点和应用注意事项。     

Reforming Watershed Restoration: Science in Need of Application and Applications in Need of Science

Coastal and inland waters are continuing to decline in many parts of the world despite major efforts made to restore them. This is due in part to the inadequate role that ecological science has played in shaping restoration efforts. A significant amount of fundamental ecological knowledge dealing with issues such as system dynamics, state changes, context-dependency of ecological response, and diversity is both under-used by managers and practitioners and under-developed by ecologists for use in real-world applications. Some of the science that is being ‘used’ has not been adequately tested. Thus, restoration ecology as a science and ecological restoration as a practice are in need of reform. I identify five ways in which our ecological knowledge should be influencing restoration to a far greater extent than at present including a need to: shift the focus to restoration of process and identification of the limiting factors instead of structures and single species, add ecological insurance to all projects, identify a probabilistic range of possible outcomes instead of a reference condition, expand the spatial scale of efforts, and apply hierarchical approaches to prioritization. Prominent examples of restoration methods or approaches that are commonly used despite little evidence to support their efficacy are highlighted such as the use of only structural enhancements to restore biodiversity. There are also major gaps in scientific knowledge that are of immediate need to policy makers, managers, and restoration practitioners including: predictive frameworks to guide the restoration of ecological processes, identification of social-ecological feedbacks that constrain ecosystem recovery and data to support decisions of where and how to implement restoration projects to achieve the largest gains. I encourage ecologists to respond to the demand for their scientific input so that restoration can shift from an engineering-driven process to a more sustainable enterprise that fully integrates ecological processes and social science methods.     

人工神经网络在水文资料插补延长中的应用

水文资料的插补延长一直是水文计算中的一个难题.本文针对水文资料的插补和水文资料的延长问题进行系统的研究.插补水文资料时,采用人工神经网络双向时间序列插补模型,打破了传统的单向时间序列识别模式,应用缺测时段前后已知时段水文资料,插补出缺测水文资料;展延长系列水文资料则应用人工神经网络参证站模型,并应用流量较大年份的径流资料预测未知年份的径流资料,来进一步提高预测精度,并结合紫坪铺流量资料插补延长实例,检验模型的可行性.结果表明该模型对水文资料的插补或对未知年份的径流量都能够进行较好的预测.     

Interactive Web-Based Map: Applications to Large Data Sets in the Geosciences

Current advances in computer hardware, information technology and data collection techniques have produced very large data sets in a wide variety of scientific and engineering disciplines. We must harness this opportunity to visualize and extract useful information from geophysical and geological data. We have taken the task of data mining by implementing a map-like approach over a web server for interrogating the data, using a client-server paradigm. The spatial-data is mapped onto a two-dimensional grid from which the user (client) can quiz the data with the map-interface as a user extension. The data is stored on the server, while the computational gateway separating the client and the server can be the front-end of an electronic publication, electronic classroom, a survey, or an e-business. We have used a combination of Java, Java3D, and Perl for processing the data and communicating between the client and the server. The user can interrogate the geospatial data over any particular region with arbitrary dimensions and then receive back relevant statistical analysis, such as the histogram plots and local statistics. We have applied this method for the following data sets: (1.) distribution of prime numbers (2.) two-dimensional mantle convection (3.) three-dimensional mantle convection (4.) high-resolution satellite reflectance data over multiple wavelengths (5.) molecular dynamics describing the flow of blood in narrow vessels. Using the map-interface, one can actually interrogate this data over the Internet.     

Combining Knowledge from Diverse Sources: An Alternative to Traditional Data Independence Hypotheses

Consider the assessment of any unknown event A through its conditional probability P(A | B,C) given two data events B, C of different sources. Each event could involve many locations jointly, but the two data events are assumed such that the probabilities P(A | B) and P(A | C) can be evaluated. The challenge is to recombine these two partially conditioned probabilities into a model for P(A | B,C) without having to assume independence of the two data events B and C. The probability P(A | B,C) is then used for estimation or simulation of the event A. In presence of actual data dependence, the combination algorithm provided by the traditional conditional independence hypothesis is shown to be nonrobust leading to various inconsistencies. An alternative based on a permanence of updating ratios is proposed, which guarantees all limit conditions even in presence of complex data interdependence. The resulting recombination formula is extended to any number n of data events and a paradigm is offered to introduce formal data interdependence.     

遥感技术在水文学中的应用与研究进展

从遥感技术在水文学中的直接和间接应用两个方面,详细阐述了遥感技术在洪水过程实时动态监测、水域面积、冰川/积雪水文、降水、区域蒸发、土壤水分、径流和水文模型、水质等领域的应用和研究进展,继而对遥感和地理信息系统在水文学中的联合应用问题进行了讨论。     

Facies Recognition Using Multifractal Hurst Analysis: Applications to Well-Log Data

Well-log (radioactivity, density and resistivity) analysis constitutes a standard approach for inferring lithology from wells. However, due to inherent complexity of the signals (such as highly heterogeneous deep-water sedimentary sequences) lithology recognition is not straightforward. We used a rescaled range analysis, calibrated with cores, to recognize lithological patterns from signal recorded along wireline logs. The detected intervals coincide with zones of visual electro-facies associations proposed by geologist well-log interpreters. In addition, we propose a rescaled range multifractal analysis to identify ranges of well-log signal complexities, which could be related to sedimentary process variations at specific stratigraphic order cycles.     

Weighting of Parts in Compositional Data Analysis: Advances and Applications

Mathematical Geosciences - It often occurs in practice that it is sensible to give different weights to the variables involved in a multivariate data analysis—and the same holds for...     

Correction to: Development and Evaluation of Geostatistical Methods for Non-Euclidean-Based Spatial Covariance Matrices

Mathematical Geosciences - The original version of this article unfortunately contained a mistake in equation 9.     

粘性土壤溶质运移新模型的应用

将Moldrup等提出的模拟水流和溶质运移的运动平均斜率模型和运动浓度斜率模型联合,模拟了重粘土在入渗和蒸发条件下的水盐动态并与特征-有限差分数值模型的计算结果进行了比较。在模拟过程中新模型显示出更加高效的优点,这对粘性土壤地区盐渍化趋势的长期预报具有重要的实际意义。     

Impact of Data Density and Geostatistical Simulation Technique on the Estimation of Residence Times in a Synthetic Two-dimensional Aquifer

Connectivity patterns of heterogeneous porous media are important in the estimation of groundwater residence time distributions (RTDs). Understanding the connectivity patterns of a hydraulic conductivity ( \(K\) ) field often requires knowledge of the entire aquifer, which is not practical. As such, the method used to estimate unknown \(K\) values using known \(K\) values is important. This study investigates how varying levels of conditioning data and four simulation techniques, one multi-Gaussian and three multi-point, are able to recreate key \(K\) field features and connectivity patterns of a synthetic two-dimensional bimodal distributed ln( \(K\) ) field with highly connected high \(K\) features. These techniques are then assessed in the context of RTD estimation. It was found that the multi-Gaussian technique presented a bias towards earlier travel times with increased conditioning data. This was due to the inability of the method to recreate multiple scales of connecting features. Of the multi-point methods investigated, the facies method was unable to predict early arrival times. The use of a continuous variable training image produced good fits to the observed residence time distribution with a high number of conditioning points. The ability of the methods to predict the shape of residence time distributions appears to be related to their ability to reproduce the connection patterns of higher \(K\) features.     

中国西部环境与生态科学数据中心：面向西部环境与生态科学的数据集成与共享

国家自然科学基金委员会“中国西部环境与生态科学研究计划”自2001年启动以来,有力地推动了西部区域环境演化、陆地生态过程和人类活动对环境的影响等方面的研究,积累了丰富的基础数据。国家自然科学基金委员会“中国西部环境与生态科学数据中心”承担“西部计划”项目数据产出的收集、管理、集成,并面向西部环境与生态科学的各个领域提供科学数据服务。“西部数据中心”的总体框架是以“西部计划”和地球系统科学发展的科学需求为导向,建成以数据共享、知识积累、合作交流和数据科学为主要内容的集成平台,为“西部计划”多学科的交叉研究和成果的综合集成及地球科学发展的长远目标服务。以共建共享的指导思想集成针对西部环境与生态现状与变化的基础背景数据、环境与生态观测数据、模型数据集、数据工具及数据文档;并以完全与开放的数据共享原则为用户提供推送式数据服务。目前,“西部数据中心”已完成了数据共享平台、知识积累平台与合作交流平台的开发和集成,初步形成了科学数据平台,整理并发布了大量的西部环境生态科学所需的关键数据集。     

Uncertainties in Facies Proportion Estimation II: Application to Geostatistical Simulation of Facies and Assessment of Volumetric Uncertainties

Geostatistical simulations of lithotypes or facies are commonly used to create a geological model and to describe the heterogeneities of petroleum reservoirs. However, it is difficult to handle such models in the framework of multiple realizations to assess the uncertainty of hydrocarbon in place. Indeed, the hydrocarbon in place is correlated with the facies proportions, which are themselves uncertain. The uncertainty model of facies proportions is not easy to describe because of closure relationships. A previous attempt was made with a nonparametric approach using the resampling technique. It has been successful in a stationary case but it is difficult to extend it to nonstationary cases. In this paper, we have applied the vectorial beta parametric model or Dirichlet model. It has provided much more realistic uncertainties on volumetrics in very different geological and geostatistical contexts.     

水文资料在水土保持中的应用研究

本文简要分析了我国水文资料的基本特点及其在水土保持中的应用情况,并结合水文资料在水土保持中的研究实例,探讨了加强水文资料在水土保持中应用范围与价值,在新一轮的站网调整建设中应与水土保持监测站网建设结合起来,避免重复建设,加强水文站网功能,发挥现有水文站网作用。     

From heartland to hegemony: Changing the world in political Geography

The heartland theory in political geography is compared with recent uses of the hegemony concept to order international relations. Both sets of ideas are described in terms of the basic content of their models, the context in which they were created, and the political contest that they prioritize. It is found that both models represent academic attempts to advise the political elites of declining major powers on how to cope with a changing world. In the final section a synthesis of the models is presented.