Some Results on the Spatial Breakdown Point of Robust Point Estimates of the Variogram

The effect of outliers on estimates of the variogram depends on how they are distributed in space. The ‘spatial breakdown point’ is the largest proportion of observations which can be drawn from some arbitrary contaminating process without destroying a robust variogram estimator, when they are arranged in the most damaging spatial pattern. A numerical method is presented to find the spatial breakdown point for any sample array in two dimensions or more. It is shown by means of some examples that such a numerical approach is needed to determine the spatial breakdown point for two or more dimensions, even on a regular square sample grid, since previous conjectures about the spatial breakdown point in two dimensions do not hold. The ‘average spatial breakdown point’ has been used as a basis for practical guidelines on the intensity of contaminating processes that can be tolerated by robust variogram estimators. It is the largest proportion of contaminating observations in a data set such that the breakdown point of the variance estimator used to obtain point estimates of the variogram is not exceeded by the expected proportion of contaminated pairs of observations over any lag. In this paper the behaviour of the average spatial breakdown point is investigated for cases where the contaminating process is spatially dependent. It is shown that in two dimensions the average spatial breakdown point is 0.25. Finally, the ‘empirical spatial breakdown point’, a tool for the exploratory analysis of spatial data thought to contain outliers, is introduced and demonstrated using data on metal content in the soils of Sheffield, England. The empirical spatial breakdown point of a particular data set can be used to indicate whether the distribution of possible contaminants is likely to undermine a robust variogram estimator.     

Spatial data for landslide susceptibility, hazard, and vulnerability assessment: An overview

The aim of this paper is to discuss a number of issues related to the use of spatial information for landslide susceptibility, hazard, and vulnerability assessment. The paper centers around the types of spatial data needed for each of these components, and the methods for obtaining them. A number of concepts are illustrated using an extensive spatial data set for the city of Tegucigalpa in Honduras. The paper intends to supplement the information given in the “Guidelines for Landslide Susceptibility, Hazard and Risk Zoning for Land Use Planning” by the Joint ISSMGE, ISRM and IAEG Technical Committee on Landslides and Engineered Slopes (JTC-1). The last few decades have shown a very fast development in the application of digital tools such as Geographic Information Systems, Digital Image Processing, Digital Photogrammetry and Global Positioning Systems. Landslide inventory databases are becoming available to more countries and several are now also available through the internet. A comprehensive landslide inventory is a must in order to be able to quantify both landslide hazard and risk. With respect to the environmental factors used in landslide hazard assessment, there is a tendency to utilize those data layers that are easily obtainable from Digital Elevation Models and satellite imagery, whereas less emphasis is on those data layers that require detailed field investigations. A review is given of the trends in collecting spatial information on environmental factors with a focus on Digital Elevation Models, geology and soils, geomorphology, land use and elements at risk.     

单斜星叶石矿物的穆斯堡尔光谱学研究

本文对产于俄罗斯希宾地区的单斜星叶石进行了不同的温度条件下的穆斯堡尔光谱效应研究.通过在温度分别在298 K,180 K和80 K条件下的分析,发现单斜星叶石由2个Fe2 和1个Fe3 四极双峰组成,并进行了单斜星叶石中的畸变参数包括八面体键角(σ2)和键长变量(△)的计算.但是,在两个畸变参数之间存在着明显的差异,将无法对它们的穆斯堡尔参数和四极双峰进行指派.本文对温度在同质异能位移和四极分裂中的作用进行了探讨,根据通过穆斯堡尔效应和f(Fe3 (O))/f(Fe2 (O))的平均值获得的三价铁对全铁的比值,改写了单斜星叶石的化学式.     

面向矿产资源信息的空间关联性分析

关联性分析是综合多源、多类数据,发现和挖掘数据中潜在的相关关系,提取和挖掘数据之间的关联性。该方法对于充分利用地质大数据、发现地质要素之间的共生组合规律具有重要的意义。本文首先基于数据的空间位置,将不同类型的地质空间数据建立联系,形成空间属性数据库;其次应用统计方法,对不同来源数据中的属性特征进行分析,发现热液型金矿的形成与火山作用存在明显相关性;最后基于Apriori算法提取热液型金矿的伴生矿与侵入岩的频繁项集,发现伴生矿与侵入岩酸碱性二者密切相关。因此,在今后的工作中,有望应用空间关联性的方法对地球物理、地球化学、遥感等多源地质数据开展深入的研究分析。     

不连续岩体变形破坏过程中AE的空间演化与意义

通过一些典型节理化岩体模型变形破坏过程中的AE事件的定位分析和破裂面形态的研究,探讨了不连续岩体变形破坏过程的空间演化特征。结果表明:单节理岩体变形破坏的空间动态特征受节理角控制,随着节理角从小变大,岩体的变形破坏方式从AE在局部集中的突发式失稳向AE弥漫于整个节理层面的类似渐进式的破坏形式发展；失稳破裂面从简单的整体状岩-膏界面变成形态复杂的层内复合破裂面；复杂节理岩体的变形破坏受一条（组）主导构造控制,强AE事件集中发生在不连续构造交汇部位,在包含多条主构造的岩体模型中最终失稳破裂面只与最后阶段AE的位置一致。     

福建港口体系结构研究

阐述了福建港湾自然条件和港口开发现状,采用赫希曼-赫芬达尔指数分析近20年来港口体系空间结构的动态演变规律,结果表明,福建港口体系空间结构演变总趋势呈分散化。这说明了港口间的竞争大于合作,职能结构趋同,因而形成合理分工与协作的福建港口群是当务之急。鉴于此,运用模糊聚类、货种区位商等分析技术,对其体系内的港口等级层次、职能结构的基本特征进行探讨,并在此基础上提出了各港口职能分工的发展方向。     

The pressure dependence of the zirconium-in-rutile thermometer

The solubility of ZrO₂ in rutile is strongly temperature-dependent and has been identified as a potentially powerful thermometer when the rutile coexists with an appropriate buffer assemblage, e.g. zircon + quartz. In combination with experimental data at 10 kbar, previous consideration of data on natural rutile has not identified a pressure dependence for the thermometer. However, the expected volume change as a result of substitution of the larger Zr⁴⁺ cation for Ti⁴⁺ suggests that the Zr content of rutile should decrease with increasing pressure. To investigate the pressure dependence of the thermometer, piston cylinder (at 10, 20 & 30 kbar) and 1 atm furnace experiments were performed in the system ZrO₂-TiO₂-SiO₂. The solubility of ZrO₂ in rutile, in the presence of zircon and quartz was reversed at each pressure value. From these experiments, the thermodynamics of the end-member reaction ZrSiO₄ = SiO₂ + ZrO₂ (in rutile) have been determined. There is a secondary pressure effect accompanying the primary temperature dependence of the Zr content of rutile. New thermometer equations are, in the α -quartz field: in the β -quartz field and in the coesite field in which φ is ppm Zr, P is in kbar and R is the gas constant, 0.0083144 kJ K⁻¹. Thermometric results using these equations are shown for a range of geological settings.     

额济纳绿洲近20年来土地覆被变化

土地利用/土地覆被变化研究是近年来全球环境变化研究的焦点之一。根据黑河下游额济纳绿洲土地生态分类,利用1982年与2000年2期TM遥感数据对比和野外实地调查,采用景观生态空间分布格局分析方法,分为河岸乔木林、河岸灌草林、荒漠稀疏灌丛、荒漠稀疏草地、河道与水域、盐碱化土地、城镇、戈壁、流动沙丘和剥蚀地山丘陵, 从各类土地分布面积变化和类型转移趋向与幅度两个方面,分析了额济纳绿洲20年来土地覆被变化。结果表明：①土地覆被类型结构发生了较大变化,河岸乔木林面积萎缩了0.97％、斑块数减小了376,而河岸灌草林增加了0.92％,数量减小1 316;而％LAND指数荒漠稀疏灌丛由4.49％增加到5.65％,由于中游来水量的锐减,河道和水域的斑块数由40个减少到6个,％LAND指数减小了0.15％。与此同时流动沙丘％LAND指数增加了0.42％。②近20年来以胡杨为主的河岸乔木林和荒漠稀疏草地减小了45.02％和14.55％,相应地以柽柳为主的河岸稀疏灌草地和荒漠稀疏灌丛增加了35.03％和25.88％;河岸乔灌林向河岸灌草林景观转移概率为45.95％,向荒漠稀疏灌丛和稀疏草地转移了0.78%和3.01％,向戈壁转移了10.87%;河岸灌草林景观类型向河岸乔灌林转移8.06％,向稀疏灌丛和稀疏草地转移10.95%和19.64%,向戈壁转移11.88％;③额济纳绿洲具有从河岸乔木→河岸灌草地→荒漠稀疏灌丛快速演化的趋势。