Scanline Method to Determine the Fractal Nature of 2-D Fracture Networks     

Tayfun Babadagli 《Mathematical Geology》2002,34(6):647-670

A previous method proposed to measure the fractal dimension of pore spaces is adapted and modified for 2-D fracture networks. The method relies on scanning a 2-D fracture network through successive straight lines from top to bottom and measuring the distance between two fractures. The fractal dimension is then obtained using the log–log plot of the feature size and the number of features for this particular size at different magnifications. It is shown in this study that the method proposed to measure the fractal dimension of porous structures can be applicable to 2-D fracture networks with some modifications after testing it on synthetic and natural fracture patterns. The method is simplified to be useful for practical applications in the fractal analysis of fracture networks. The results reveal that, on the basis of the direction of scanning lines, different fractal behavior and dimensions can be obtained indicating that 2-D fracture networks possess multifractal character. This approach takes into account the effect of fracture orientation on the fractal behavior and anisotropic nature of fracture networks as well as the fracture density, length, and spatial distribution.  相似文献   

城市人口GIS中数据的不确定性研究   总被引：8，自引：0，他引：8  

柳宗伟  王新洲  陈顺清 《武汉大学学报(信息科学版)》2002,27(6):627-631

针对系统数据源、数据模型的不确定性以及分析过程中引入的不确定性等问题进行了系统的研究，并归纳了各种不确定性的影响模型，进而提出了一套人口GIS数据优化建模以及分析过程中人口密度中心建模的思想和实用方法，用于克服人口GIS中数据的不确定性的影响。  相似文献   

三江地区重力场特征和岩石圈构造   总被引：2，自引：0，他引：2  

蒋福珍 《武汉大学学报(信息科学版)》2002,27(2):122-126

利用重力、地震层析成像等多种资料 ,并利用场分离、正反演以及阻尼最小二乘法、约束最小二乘法等数学方法 ,对重力异常进行分离 ,用地震层析成像的结果作为约束进行反演 ,得到地壳上地幔不同深度的密度分布和莫霍面深度等结果。  相似文献   

高密度电阻率法二维反演在工程勘探中的应用   总被引：7，自引：0，他引：7  

何门贵  温永辉 《物探与化探》2002,26(2):156-159

应用高密度电阻率法二维反演方法能够提高资料解释的准确性。通过几个最小二乘法反演在工程勘探中的应用实例,说明高密度电阻率法二维反演处理的优越性。  相似文献   

上海城区建筑密度与地面沉降关系分析   总被引：26，自引：0，他引：26  

严学新  龚士良  曾正强  俞俊英  沈国平  汪铁骏 《水文地质工程地质》2002,29(6):21-25

工程建设逐渐成为上海近年来新的地面沉降制约因素，本文选择4个典型的高层建筑及多层建筑密集区段，分析了建筑密度与地面沉降的关系，探讨了其时空变化特征，建筑规模及其增长速度直接导致工程性地面沉降同步增长，集中建设较分散建设，新区建设较旧城改造、高层建筑较多层建筑地面沉降效应明显。建筑密度越大，建筑容积率越高，地面沉降越显著。城市规划宜选择低密度、低容积率的建设模式，降低建筑高度，扩大建筑间距。提出了沉降控制条件下适宜的建筑容积率应在0.9～1.2之间，从而为城市规划提供了决策性技术指标。  相似文献   

高浓度有机废水化学和物理法处理技术综述   总被引：3，自引：0，他引：3  

徐文炘  李蘅  张生炎  扈胜禄  黄伟 《矿产与地质》2002,16(6):369-371

介绍国内外高浓度有机废水应用化学和物理方法处理技术进展 ,通过比较各种化学和物理方法的优缺点 ,得出探讨性结论 ,即采用一种方法难以完全处理高浓度有机废水 ,需经二段或三段处理方法处理后 ,才能达到排污标准。  相似文献   

Possible mechanisms of magma redistribution under Mt Etna during the 1994–1999 period detected through microgravity measurements     

D. Carbone  G. Budetta  F. Greco 《Geophysical Journal International》2003,153(1):187-200

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The Influence Of Vertical Wind Direction Shear On Dispersion In The Convective Boundary Layer, And Its Incorporation In Coastal Fumigation Models     

Ashok K. Luhar 《Boundary-Layer Meteorology》2002,102(1):1-38

The mean concentration distributionwithin a plume released from a point source in the atmosphericboundary layer can be greatly influenced by the systematic turningof wind with height (i.e. vertical wind direction shear). Such aninfluence includes a deflection of the plume centroid, with anassociated shearing of the vertical plume cross-section, and anenhancement of dispersion, in the horizontal plane. Wind directionshear is normally not accounted for in coastal fumigation models,although dispersion observations with shear acting as acontrolling parameter are not uncommon. A three-dimensionalLagrangian stochastic model is used to investigate the influenceof uniform wind direction shear on the diffusion of a point-sourceplume within the horizontally homogeneous convective boundarylayer, with the source located at the top of the boundary layer.Parameterisations are developed for the plume deflection andenhanced dispersion due to shear within the framework of aprobability density function (PDF) approach, and compared with theLagrangian model results. These parameterisations are thenincorporated into two applied coastal fumigation models: a PDFmodel, and a commonly used model that assumes uniform andinstantaneous mixing in the vertical direction. The PDF modelrepresents the vertical mixing process more realistically. A moreefficient version of the PDF model, which assumes a well-mixedconcentration distribution in the vertical at large times, isapplied to simulate sulfur dioxide data from the Kwinana CoastalFumigation Study. A comparison between the model results and thedata show that the model performs much better when the wind-sheareffects are included.  相似文献   

A stochastic approach to site-response component in seismic ground motion coherency model     

S. Liao  J. Li 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):813-820

In order to account for the site-response part of the seismic ground motion coherency for sites of interest, an analytical stochastic methodology is proposed in this paper. By combining the pseudo-excitation method with wave motion finite element simulation techniques, a numerical approach for the computation of the coherency function between observation points is developed firstly. Then the orthogonal expansion method is introduced into this approach to study the effect of the uncertainty in soil properties on the coherency function. Finally some numerical examples are given to show the applicability of the methodology. The computational results demonstrate that the lagged coherency values tend to decrease in the vicinity of the resonant frequencies of the site.  相似文献   

A comparison of procrystal and ab initio model representations of the electron-density distributions of minerals     

R. T. Downs  G. V. Gibbs  M. B. Boisen Jr  K. M. Rosso 《Physics and Chemistry of Minerals》2002,29(5):369-385

 The procrystal calculation of the electron density is a very rapid procedure that offers a quick way to analyze various bonding properties of a crystal. This study explores the extent to which the positions, number, and properties of bond-critical points determined from the procrystal representations of the electron density for minerals are similar to those of first-principles ab initio model distributions. The purpose of the study is to determine the limits imposed upon interpretation of the procrystal electron density. Procrystal calculations of the electron density for more than 300 MO bonds in crystals were compared with those previously calculated using CRYSTAL98 and TOPOND software. For every bond-critical point found in the ab initio calculations, an equivalent one was also found in the procrystal model, with similar magnitudes of electron density, and at similar positions along the bonds. The curvatures of the electron densities obtained from the ab initio and the procrystal distributions are highly correlated. It is concluded that the procrystal distributions are capable of providing good estimates of the bonded radii of the atoms and the properties of the electron-density distributions at the bond-critical points. Because the procrystal model is so fast to compute, it is especially useful in addressing the question as to whether a pair of atoms is bonded or not. If the Bader criteria for bonding are accepted, then the successful generation of the bond-critical points by the procrystal model demonstrates that bonding is an atomic feature. The main difference between the critical-point properties of the procrystal and the ab initio model is that the curvature in the electron density perpendicular to the bond path of the ab initio model is sharper than for the procrystal model. This is interpreted as indicating that the electrons that migrate into a bond originate from its sides, and not from the regions closer to the nuclei. This observation also suggests that ab initio optimization routines could see an improvement in speed if the parameters relating to the angular components of atomic wave functions were to vary before the radial components. Received: 6 August 2001 / Accepted: 21 November 2001  相似文献