Uncertainty,entropy, scaling and hydrological stochastics. 2. Time dependence of hydrological processes and time scaling / Incertitude,entropie, effet d'échelle et propriétés stochastiques hydrologiques. 2. Dépendance temporelle des processus hydrologiques et échelle temporelle

Abstract

The well-established physical and mathematical principle of maximum entropy (ME), is used to explain the distributional and autocorrelation properties of hydrological processes, including the scaling behaviour both in state and in time. In this context, maximum entropy is interpreted as maximum uncertainty. The conditions used for the maximization of entropy are as simple as possible, i.e. that hydrological processes are non-negative with specified coefficients of variation and lag-one autocorrelation. In the first part of the study, the marginal distributional properties of hydrological processes and the state scaling behaviour were investigated. This second part of the study is devoted to joint distributional properties of hydrological processes. Specifically, it investigates the time dependence structure that may result from the ME principle and shows that the time scaling behaviour (or the Hurst phenomenon) may be obtained by this principle under the additional general condition that all time scales are of equal importance for the application of the ME principle. The omnipresence of the time scaling behaviour in numerous long hydrological time series examined in the literature (one of which is used here as an example), validates the applicability of the ME principle, thus emphasizing the dominance of uncertainty in hydrological processes.     

饱和土变形过程模拟的统计损伤方法研究

针对传统损伤理论的不足与局限性,从研究岩土材料损伤的合理定义入手,并通过深入探讨饱和土损伤的微观力学机制,建立了适合于饱和土的新型损伤模型。在此基础上,引进统计损伤理论,建立了模拟特定围压下饱和土变形全过程的统计损伤本构模型及其参数确定方法。通过探讨饱和土损伤统计本构模型参数与围压的关系,建立了该模型的合理修正方法,从而建立了反映不同围压条件的统一饱和土损伤统计本构模型。理论与试验结果分析表明了该模型的合理性,该模型不仅能反映饱和土的变形全过程,而且能反映孔隙水压力对饱和土变形的影响。     

基于空间分析方法的中国区域差异研究

利用中国1952~2000年各省区的人口、土地利用和人均GDP等数据,采用空间分析方法对中国区域社会经济发展差异问题进行了实证研究。对中国大陆的几何中心、可利用土地、人口和GDP总量的空间中心计算表明,空间中心统计是一种简单有效刻画要素空间分布的方法。通过对中国各省区人均GDP的空间自相关系数Moran's I的计算,表明中国社会经济发展主要指标存在强烈的空间自相关,空间分析方法不失为一种深入理解区域经济格局及其变化的重要和有益的方法。对不同年度的Moran's I和Local Moran I的分析也揭示了中国区域经济格局的时空变化规律。     

地震活动性统计学研究方法的若干进展与讨论

对统计学方法在地震活动性研究中的部分重要成果、最新研究进展进行了简要地回顾。重点介绍了余震衰减关系和震级、频度关系的相关研究成果及地震活动过程随机模拟等的发展趋势。     

基岩裂隙流水位与流程关系的统计研究

基于室内模拟试验及有关资料,研究了不同条件下基岩裂隙水一维流水位与流程的统计关系,并将结果与前人研究进行了比较分析,得出以下结论:a.基岩裂隙水无压流水位三次方与流程呈线性关系,承压流水头与流程呈线性关系;b.承压流条件下统计结果与前人研究结果无实质性差别,而对无压流,统计结果与孙峰根等人的研究结果一致,与传统的结果,即水位平方和流程呈线性关系不一致;c.统计结果对基岩裂隙水运动理论的研究与应用具有重要的参考价值      

Ground and building extraction from LiDAR data based on differential morphological profiles and locally fitted surfaces

This paper proposes a new framework for ground extraction and building detection in LiDAR data. The proposed approach constructs the connectivity of a grid over the LiDAR point-cloud in order to perform multi-scale data decomposition. This is realised by forming a top-hat scale-space using differential morphological profiles (DMPs) on points’ residuals from the approximated surface. The geometric attributes of the contained features are estimated by mapping characteristic values from DMPs. Ground definition is achieved by using features’ geometry, whilst their surface and regional attributes are additionally considered for building detection. A new algorithm for local fitting surfaces (LoFS) is proposed for extracting planar points. Finally, transitions between planar ground and non-ground regions are observed in order to separate regions of similar geometrical and surface properties but different contexts (i.e. bridges and buildings). The methods were evaluated using ISPRS benchmark datasets and show superior results in comparison to the current state-of-the-art.     

Comparisons of u ‐, g ‐, r ‐, i ‐, and z ‐band luminosity distributions between galaxy members of compact groups and isolated galaxies

To investigate the environmental dependence of u ‐, g ‐, r ‐, i ‐, and z ‐band luminosities, we perform comparative studies of luminosity distributions between galaxy members of compact groups (CGs) and isolated galaxies. It is found that for the r, i, and z bands isolated galaxies have a higher proportion of faint galaxies and a lower proportion of luminous galaxies than galaxy members of CGs, but for the u band an opposite trend is observed. The correlation between the g ‐band luminosity and the environment has different trends in different luminosity regions (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

同等质量下盘状星系的颜色-尺度关系

挑选Sloan数字巡天第7次释放数据(SDSS DR7)的主星系样本中近邻的、面向的盘状星系作为星系样本,统计研究了在恒星总质量相等的情况下盘状星系的颜色和尺度之间的相关性,并对相关性的真实性进行了检验.发现对于同等质量的盘状星系,u-r颜色与尺度相关性很弱,而g-r、r-i、r-z颜色与尺度负相关,即星系的尺度越大,颜色越蓝.该结果意味着盘状星系的质量分布对其恒星形成历史影响很大,物质分布越延展的星系,其演化越慢.     

地面岩（矿）层厚度计算公式的数学推导

地面岩（矿）层厚度计算公式是地质工作者常用的、基本的地（矿）层厚度计算公式,本文用数学方法系统推导,并阐明岩（矿）层真厚度、地表实测岩（矿）层长度、岩（矿）层倾角、地面坡角、岩（矿）层走向法线与岩（矿）层实测线的交角及岩（矿）层走向与岩（矿）层实测线的交角之间的数学关系,证明地面岩（矿）层厚度计算公式的可靠性及其数学的严谨性.     

Serviceability limit state design for uplift of helical anchors in clay

Presently, no displacement-based design methodology exists for helical anchors subjected to tensile or uplift loading. This study investigates the statistical and probabilistic aspects of the load-displacement uncertainty associated with a database of thirty-seven uplift loading tests of helical anchors founded within cohesive soils. Initially, an ultimate resistance model is identified, and the semi-empirical uplift breakout factor statistically characterized. A relationship between ultimate resistance and slope tangent capacity is established, and used to form the basis for normalizing the load-displacement response. Hyperbolic and power law models are statistically evaluated for use in serving as a reference load-displacement model; the hyperbolic curve was selected based on goodness-of-fit statistics. Monte Carlo reliability simulations are used to establish an equivalent-deterministic load factor that associates the selected load factor with a probability of exceeding a pre-determined allowable uplift displacement, given uncertainty in the undrained shear strength, ultimate resistance model, transformation uncertainty, uncertainty in the allowable displacement, and variability in uplift loading. A practical example is provided to show the intended use of this probabilistic helical anchor displacement model.