The Fourier Integral Method: An efficient spectral method for simulation of random fields

The Fourier Integral Method (FIM) of spectral simulation, adapted to generate realizations of a random function in one, two, or three dimensions, is shown to be an efficient technique of non-conditional geostatistical simulation. The main contribution is the use of the fast Fourier transform for both numerical calculus of the density spectral function and as generator of random finite multidimensional sequences with imposed covariance. Results obtained with the FIM are compared with those obtained by other classic methods: Shinozuka and Jan Method in 1D and Turning Bands Method in 2D and 3D, the points for and against different methodologies are discussed. Moreover, with the FIM the simulation of nested structures, one of which can be a nugget effect and the simulation of both zonal and geometric anisotropy is straightforward. All steps taken to implement the FIM methodology are discussed.     

三分量地震资料中各向异性检测

各向异性研究是当令地震学研究领域中重要课题之一；三分量地震资料中各向异性的检测是各向异性理论研究成果解决地球科学实际问题的重要桥梁。本文简要描述了各向异性介质中横波分裂现象，分别介绍了现有的四种主要检测技术，即偏振图法、协方差拒阵法、质，点振动分辨率法及传输矩阵法，并对这四种技术作了一定的评述。     

用解析有限元法嵌入地下水管理模型求最优解

为了弥补当前地下水资源优化管理模型中通用的两种构模方法的缺点,即嵌入法的代数方程组过于庞大、上机困难,和响应矩阵法不保证全局最优,提出了用解析有限元法建立整体非稳定(即带有时间变量)抽水响应矩阵作为约束条件嵌入线性规划模型.这一方法由于具备了空间上表达任一节点在任一时刻的地下水运动规律的能力,克服了上述构模的两大缺点,其推广应用将有利于提高地下水资源的优化开发和管理.     

Rangeland production: use of models incorporating aggregated knowledge and fuzzy construction

This work reports on a method using fuzzy membership functions to construct an aggregated interaction matrix in which the summation of variables is scaled according to the way rainfall and soil variables affect water availability to plants and hence influence rangeland productivity. Aggregation of the variables gives a comprehensive value which can be used to predict production. The model increases the predicability of production to 81% compared to models using rainfall alone and a multiplicative parametric one which give predictibilities of 61 and 76% respectively. The results showed that (1) the importance of rainfall in determining production was most important at lower rainfalls i.e. <350 mm; (2) soil texture and particularly slope were important through out the rainfall range (149–700 mm) investigated; and (3) soil depth was only important at the higher >350 mm rainfalls. The aggregated interaction matrix gives a measure of land productive capability.     

统一方差分量估计公式

本文提出了一种适用于协方差阵奇异或非奇异、设计阵列满秩或降秩时的方差分量估计方法;其公式推导简单,形式统一,不需解线性方程组,同时可保证迭代计算方差分量的非负要求。作为特例还和Helmert法及MINQUE法作了比较。最后讨论了用真误差进行方差分量估计的计算公式,并给出了一个测距误差分析的实例。     

GPS工程控制网最优化设计的研究

本文讨论了GPS工程控制网的最优化设计问题;通过对GPS工程控制网的精度和可靠性分析,建立了应用点位精度矩阵相关性优化GPS网的数学模型;针对解算中存在的问题,提出了最短路径法寻找整数变量线性规划问题的最优解。     

ESR assessment of kerogen maturation and its relation with petroleum genesis

Petroleum hydrocarbons are formed by breakdown of kerogen preserved in source rocks throughout the process of catagenesis. This process is accompanied by free radical generation in kerogen. The availability of measuring free radicals in kerogen using ESR to deduce a maturation estimation of potential source rocks has been hindered due to the presence of the solvent-extractable organic molecules (SEOM) trapped within the kerogen matrix. Spin concentration (Ns) of the kerogen treated with pyridine (K_Py) represents the paramagnetic centers of the kerogen matrix itself and provides a potential parameter to evaluate kerogen maturation.