Characterization of Distributional Forms for Compositional Data and Associated Distributional Tests

A variety of approaches to the testing of distributional forms for compositional data has appeared in the literature, all based on logratio or Box–Cox transformation techniques and to a degree dependent on the divisor chosen in the formation of ratios for these transformations. This paper, recognizing the special algebraic–geometric structure of the standard simplex sample space for compositional problems, the use of the fundamental simplicial singular value decomposition, and an associated power-perturbation characterization of compositional variability, attempts to provide a definitive approach to such distributional testing problems. Our main consideration is the characterization and testing of additive logistic–normal form, but we also indicate possible applications to logistic skew normal forms once a full range of multivariate tests emerges. The testing strategy is illustrated with both simulated data and applications to some real geological compositional data sets.     

A contribution to the theory of variation diagrams

Harker diagrams and other ternary weight per-cent diagrams distort genetic trends by changing their slopes. They can not be readily used to discriminate between rival hypotheses. Two theorems have been proven which show the desirability of using certain types of ratios, instead of per-cent values, for comparisons. It is suggested that, when it is desired to discriminate between rival hypotheses, or to determine the exact variation between components, weight per-cent comparisons be discontinued (wherever possible) in favour of molar ratio comparisons in which one of the components (the divisor) is a constant. Variation diagrams of this type offer reliable discrimination between rival hypotheses, and yield the true relationship between variables in every case. An example involving crystal fractionation of olivine and pyroxene from a basic sill is developed in detail, and other potential uses are mentioned. This technique is completely general and is not restricted to chemical components, or to any scale of system, or to any field of study, providing certain essential conditions are fulfilled.     

山西洪洞王绪黄土地层划分

通过对临汾盆地王绪及其邻近地区黄土地层中所含抱子花粉、右脊椎动物化石、颗粒成分、磁化率、古土壤、结构构造以及接触关系等综合研究,将王绪剖面上的黄土划分为下更新统、中更新统及上更新统三层,并同洛川、午城两地区的午城黄土、离石黄土及马兰黄土地层对比。     

克立格估计的分析解释与协方差函数的代数确定

首先引入利用旋转面作为基函数的函数逼近概念, 在此基础上经过复杂的矩阵推导证明泛克立格法可表示为传统的带权最小二乘多项式拟合与以旋转面作为基函数的函数逼近, 并在一定条件下(随机场高度连续无块金效应) 论证了协方差(即旋转面) 的参数可通过数学分析的方法确定, 给出了以高斯函数为例确定协方差函数的两个准则.      

The Seyfert 1 galaxy Ark 120 in 1996–2005. Temporal characteristics of the optical variability

We study the optical variability of the Seyfert galaxy Ark 120 using the autocorrelation and structure functions, as well as a periodogram analysis, based on our 1996–2005 U BV RI observations. The autocorrelation function indicates an increase in the correlation to 70% for time shifts of about 430 days. The structure function displays a decrease for these same time shifts, which is interpreted as evidence for periodic events on these timescales. The structure function indicates an increase in the variability amplitude with increasing duration of the variable process. On large time scales, the structure function can be presented as a power-law function with index 0.8–0.9, possibly indicating the presence of unstable processes in the accretion disk. Our search for periodicity in the light curves has revealed a possible period P = 430 days, which has been observed during 13 cycles, as follows from an analysis using continuum from spectral data obtained from 1988 to 2005.     

The Role of non-timber forest products as safety-nets: A review of evidence with a focus on South Africa

Poor, rural communities are vulnerable to adversity. To secure their livelihoods, people adopt multiple livelihood strategies, including using non-timber forest products (NTFPs). NTFPs have been identified as important to rural livelihoods, as an alternative land-use option as well as in fulfilling an important safety-net function although empirical evidence on the latter’s strength is limited. Whilst NTFPs may contribute towards alleviating poverty, this safety-net function needs more critical and quantitative investigation. This includes the establishment of an applicable definition so this function can be communicated to policy makers and taken into account in national poverty alleviation strategies and, in attempts to promote resource-conserving behaviour by highlighting the value of natural resources (including NTFPs) compared to alternative land-use options. Poverty in rural households is complex and households are vulnerable to a range of shocks. During adversity households can turn to a range of possible safety-nets. What determines the use of NTFPs as a safety-net, how this safety-net function manifests and the strength of this function is poorly understood and there is need for further investigation.     

Distribution of hydrocarbon accumulations in a basin: a mathematical model for the West Siberian petroleum province

The distribution of hydrocarbon accumulations in a basin is modeled as a nonstationary Poisson field of points with the average density of accumulations as a function of distance from the basin margin. The model, in which this distance is a unique parameter to define the intensity function, is suitable, in a first approximation, for Monte-Carlo simulation of the real pattern of accumulations. The Poisson random field of points is described with a power function, where the power is a fractal dimension used as an integral numerical parameter of the distribution.     

灾害防御工程的经济效益评价原理及方法——以水坝震害防御工程为例

根据价值工程理论和成本-效益理论,在作者提出的防灾工程功能函数、成本函数、价值函数、效益函数等灾害经济学基本函数及数学模型的基础上,结合地质灾害防御工程实例,探讨了防灾工程经济效益的评价原理及方法。     

功能可配制的GIS服务引擎

为解决基于软件即服务架构地理信息系统(geographic information system,GIS)的四级模型中有关功能可配置、可扩展和多用户效率的技术难题,提出了功能可配制的GIS服务引擎模型框架,并介绍了功能可配制的GIS服务引擎的核心技术——工作流技术、功能仓库技术、搭建与配置技术、权限管理技术等,同时给出了一个基于功能可配制的GIS服务引擎技术构建遥感影像系统的应用实例,为软件即服务这一新的软件应用模式提供了技术支撑.      

Non-linear analysis for calculating the support of a rock block with dilatant joint faces

In jointed rock masses the instability of individuals, discrete blocks is a concern. In underground excavations it is necessary to know how much support is required for “key blocks” in the roof. As these blocks fall, dilatancy of the block's bounding joints tends to keep the block in contact with the surrounding rock mass. Shear stresses devloped along the joints as a result of this contact and help to support the block. By knowing the initial stress field and the shear properties of the joint, as a function of stress and displacement, a non-linear analysis can determine the normal and shear stresses on the bounding joints as a function of the displacement path. The amont of support required to keep the block in the roof can then be determined as a function of displacement.     

WA联合ELM与OS-ELM的滑坡位移预测模型

滑坡累积位移监测曲线往往呈现出复杂的非线性增长特性,对此建立了不少相关的预测模型,而以往的预测模型存在着许多不足。本文基于小波函数（Wavelet Analysis,WA）,ELM与OS-ELM,提出一种名为WA联合ELM、OS-ELM的预测方法。首先,该方法基于小波函数,将滑坡累积位移分解成受内部地质条件影响的趋势项和受外部影响因子影响的周期项;然后,基于ELM与OS-ELM分别对趋势项和周期项进行预测;最后将趋势项和周期项的预测值叠加得到累积位移的预测值。结果表明,小波函数得到的趋势项展现出良好的趋势性,而周期项也展现出良好的周期性;以Sigmoid方程为核函数,隐含层神经元个数为33的ELM模型能准确高效对趋势项进行预测,而以RBF方程为核函数,隐含层神经元个数为100的OS-ELM模型能准确高效对周期项进行预测;累积位移预测数据的RMSE分别为0.1423和0.1315,预测结果相对较好,能够在滑坡位移预测领域发挥一定的作用。     

Practical considerations in the application of simulated annealing to stochastic simulation

Realizations generated by conditional simulation techniques must honor as much data as possible to be reliable numerical models of the attribute under study. The application of optimization methods such as simulated annealing to stochastic simulation has the potential to honor more data than conventional geostatistical simulation techniques. The essential feature of this approach is the formulation of stochastic imaging as an optimization problem with some specified objective function. The data to be honored by the stochastic images are coded as components in a global objective function. This paper describes the basic algorithm and then addresses a number of practical questions: (1) what are the criteria for adding a component to the global objective function? (2) what perturbation mechanism should be employed in the annealing simulation? (3) when should the temperature be lowered in the annealing procedure? (4) how are edge/border nodes handled? (5) how are local conditioning data handled? and (6) how are multiple components weighted in the global objective function?     

论直流电位场拟解析近似中的电位与电荷反射函数的物理意义

为了避开由大型代数方程组数值求解所带来的问题,将电场反射张量的基本概念和拟解析近似的基本思想引入到了直流电位场的数值模拟中,定义了体电位反射函数、面电荷反射函数和面电位反射函数等3个辅助函数,并给出了其在一般条件下的拟解析近似解和在简单条件下（均匀或点电流源背景场、均匀导电柱体或球体）的分析解。简单的对比分析证明：面电荷反射函数是异常体表面上自由面电荷密度的函数;在简单条件下,这种函数关系转化成为比例关系;类似的结论对于简单条件下的面电位反射函数也成立;然而,在一般条件下难以建立面电位反射函数和自由面电荷密度之间的明确关系。     

粒度分布数据的计算机光滑插值绘线方法

以一种单调光滑的分段插值函数为基础，在计算机上实现了光滑的粒度分布累积频率曲线和频率分布曲线的绘制。这一方法为编制软件在计算机上实现粒度分析数据高效高质量的系统处理提供了基础，为粒度分布特征的普遍表述向更精确、更全面的方向深化提供了途径。     

温度影响溴和铷分配的热力学分析及在钾盐矿床中的应用

在海相蒸发岩矿床的地质-地球化学研究中,常应用盐类矿物中的微量元素来研究钾盐矿床的成因和成矿指示标志,Br、Rb就是其中很重要的2种微量元素。缺硫酸镁型钾盐矿床在成盐过程中会蒸发沉积形成氯化物型的盐类物质, Br、Rb按一定的规律分配到这些盐类物质中而不形成独立矿物。在盐类物质蒸发结晶过程中,Br、Rb在固_液相之间的分配主要受温度控制。文章通过Br和Rb的地球化学特征及微量元素分配的热力学分析,建立了Br、Rb在盐类矿物相中的分配系数与温度间的热力学函数模型:,并探讨了利用这些公式来计算出钾盐矿床结晶作用形成盐类物质时的古温度,这对研究钾盐矿床形成时的古环境、物质基础条件、物理化学条件等具有重要意义。     

地下水可持续开采量与地下水功能评价的关系

针对中国北方地下水评价中偏重资源而对地下水的生态功能和地质环境功能重视不足的问题,立足于流域尺度的地下水循环系统和地下水的自然属性,突出协调综合发挥地下水的资源功能、生态功能和地质环境功能的目标,从地下水可持续开采量与地下水功能的理念基础、评价原则和评价机理3个方面探讨二者的内在关联性,认为它们同源于人与自然和谐的理念,都以流域尺度的地下水循环系统为研究主体,以保护生态与地质环境为目标,彼此相互促进和相互支撑.地下水功能评价是合理确定地下水可持续开采量的充分条件,地下水可持续开采量的合理确定是实现地下水功能评价目标的必要条件;如果二者缺一,则地下水的生态功能或地质环境功能难以得到有针对性的保护.     

Magnetic and coagulation forces on a suspension of magnetic particles

It is shown that the magnetic force on a highly-magnetic particle in a slurry is a strong function of the particle shape and the concentration density of the magnetic particles in the suspension. An expression is derived for the coagulation forces between magnetized particles as a function of magnetic moment, size, and concentration.     

Shape optimisation of the support section of a tunnel at great depths

The shape optimisation of a cavity is typically performed without considering the previous support, which may significantly reduce the practical significance of such analyses. Even when an excavation section is optimised, failure of the surrounding rock in a tunnel cannot be prevented in the presence of excessive in situ stress. Thus, a support should be established to protect the stability of a tunnel from the failure of the surrounding rock. This study examines the optimal shape of the support that satisfies the optimisation criterion, which minimises the largest tangential stress along the inner edge of the support, for a specific net tunnel size and support strength. The optimisation process is to solve a series of forward problems using the conformal mapping method for a plane elasticity complex function. The tangential stress along the inner edge of the support is selected as the objective function, and the coefficients of the mapping function are considered as the design variables. The minimum value of the objective function is calculated based on the mixed penalty function method and the optimal support shape that satisfies the given constraints can be obtained. The stress state of an optimally shaped tunnel support is significantly improved compared to non-optimal configurations, and the stress concentration along the inner edge of the support is minimised.     

Multiscale finite-volume method for density-driven flow in porous media

The multiscale finite-volume (MSFV) method has been developed to solve multiphase flow problems on large and highly heterogeneous domains efficiently. It employs an auxiliary coarse grid, together with its dual, to define and solve a coarse-scale pressure problem. A set of basis functions, which are local solutions on dual cells, is used to interpolate the coarse-grid pressure and obtain an approximate fine-scale pressure distribution. However, if flow takes place in presence of gravity (or capillarity), the basis functions are not good interpolators. To treat this case correctly, a correction function is added to the basis function interpolated pressure. This function, which is similar to a supplementary basis function independent of the coarse-scale pressure, allows for a very accurate fine-scale approximation. In the coarse-scale pressure equation, it appears as an additional source term and can be regarded as a local correction to the coarse-scale operator: It modifies the fluxes across the coarse-cell interfaces defined by the basis functions. Given the closure assumption that localizes the pressure problem in a dual cell, the derivation of the local problem that defines the correction function is exact, and no additional hypothesis is needed. Therefore, as in the original MSFV method, the only closure approximation is the localization assumption. The numerical experiments performed for density-driven flow problems (counter-current flow and lock exchange) demonstrate excellent agreement between the MSFV solutions and the corresponding fine-scale reference solutions.