A new scheme for numerical modelling of flow and transport processes in 3D fractured porous media

The objective of this work is to develop a new numerical approach for the three-dimensional modelling of flow and transient solute transport in fractured porous media which would provide an accurate and efficient treatment of 3D complex geometries and inhomogeneities. For this reason, and in order to eliminate as much as possible the number of degrees of freedom, the fracture network, fractures and their intersections, are solved with a coupled 2D–1D model while the porous matrix is solved independently with a 3D model. The interaction between both models is accounted for by a coupling iterative technique. In this way it is possible to improve efficiency and reduce CPU usage by avoiding 3D mesh refinements of the fractures. The approach is based on the discrete-fracture model in which the exact geometry and location of each fracture in the network must be provided as an input. The formulation is based on a multidimensional coupling of the boundary element method-multidomain (BEM-MD) scheme for the flow and boundary element dual reciprocity method-multidomain (BE-DRM-MD) scheme for the transport. Accurate results and high efficiency have been obtained and are reported in this paper.     

Probabilistic impedance of foundation: Impact of the seismic design on uncertain soils

In the linear seismic design of buildings, the (deterministic) substructure method is a customary and efficient approach. However, the existence of spatial variability in the parameters of the mechanical model of the soil, as well as parametric errors, calls for the use of probabilistic approaches in order to provide a reliable design of the structure. The construction of probabilistic models of the soil impedance matrix provides a natural path to such approaches within the context of the substructure method. Two main techniques are described in this paper: a parametric one, typically using the stochastic finite element method, and a nonparametric one, which was introduced more recently. The latter is explored more specifically, and the possibilities it offers in terms of seismic design are presented. In particular, it is shown that it allows for the estimation of quantiles of the quantities of interest, rather than confidence intervals, which lead to highly conservative design. Copyright © 2008 John Wiley & Sons, Ltd.     

正交矩阵的若干性质

通过对正交矩阵的深入研究，得到正交矩阵的一系列常用性质。     

区域经济联系定量分析初探：以上海与苏锡常地区经济联系为例

针对目前区域联合日益广泛和经济联系量化研究不足的现状，在联系强度等方面提出一些新概念；阐述了经济联系量化指标的选取，建立了经济联系定量分析模型。     

地基沉降预测模型的正则化算法

通过分析地基沉降预测模型,指出最小二乘的病态性会导致模型参数求解失败。应用正则化理论,基于矩阵求逆理论,提出了一种沉降预测模型参数的正则化无偏估计算法,说明了新算法的无偏性和方差最小性。在一定条件下,证明了新算法中正则参数的存在性,并给出了正则参数的计算公式。结合文献和工程实例进行的分析表明,新算法降低了矩阵条件数,减轻矩阵病态程度,能有效求得地基沉降预测模型参数。     

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。     

声波方程频率域有限元参数反演

推导出频率域有限元声波正演方程,为了消除边界反射,将Clayton-Engquist旁轴波动方程吸收边界条件引入频率域,并对有限元刚度矩阵和质量矩阵进行压缩存储,利用广义共轭梯度法求解有限元方程获得正演解.在此基础上,推导出在某一频率下波场数据残差δU与单元物性参数修改量δλ之间关系的Jacobi矩阵,反演方法允许利用地面二维炮集全波场资料与给出初始模型参数的正演值的差值δU,迭代求得δλ.由于计算机内存的限制,方法计算不允许有过多数目的未知数个数,因此还提出了对同一介质物性单元的Jacobi矩阵元素进行压缩组装的措施,从而使反演的未知量个数减少,结合采用共轭梯度迭代法,使得只需利用有效波频段的少数一些频率即可进行迭代反演.正演和反演理论模型的数值模拟结果表明方法是有效的.     

火焰原子吸收光谱法测定固态磷矿散源中的钾钠

本文研究了用微波炉在自制聚四氟乙烯闭容器内,用ＮＨＯ３－ＨＦ增压分解样品,即解决了样品分解的难题,又减少了污染。并于标准系列中外加基体元素消除了基本的干扰,以ＦＡＡＳ测定Ｋ２Ｏ和Ｎａ２Ｏ。     

山东昌乐凹陷油页岩地球化学特征及成因探讨

山东昌乐凹陷油页岩出产于古近系五图群李家崖组,与济阳拗陷和潍北凹陷孔二段相当。利用有机地球化学方法对昌乐凹陷油页岩品质进行分析,结果显示该区油页岩有机质丰度较高、干酪根类型主要为Ⅰ型和Ⅱ₁型,处于未熟低熟阶段,具有较好的勘探开发前景。通过区域构造演化和气候变化分析,昌乐凹陷油页岩形成于郯庐断裂带左旋右旋转换期,构造活动强度较弱加之温暖湿润的气候环境促成了油页岩的发育。油页岩与煤共生于水进体系域和高水位体系域之中,油页岩成矿模式为断陷湖沼型。