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21.
R.P. Gupta D.P. Kanungo M.K. Arora S. Sarkar 《International Journal of Applied Earth Observation and Geoinformation》2008
Evaluation of maps generated from different conceptual models or data processing approaches at spatial level has importance in many geoenvironmental applications. This paper addresses the spatial comparison of different landslide susceptibility zonation (LSZ) raster maps of the same area derived from various procedures. 相似文献
22.
分析了GPS卫星预报星历,在比较分析EKF和UKF优缺点的基础上,将UKF引入GPS卫星轨道预报研究中.数值模拟和结果分析表明,UKF方法预报更稳定,能有效地提高轨道预报精度和稳定性. 相似文献
23.
Martin Rosner Michael Wiedenbeck Thomas Ludwig 《Geostandards and Geoanalytical Research》2008,32(1):27-38
An analytical artefact is reported here related to differences in instrumental mass fractionation between NIST SRM glasses and natural geological glasses during SIMS boron isotope determinations. The data presented demonstrated an average 3.4‰ difference between the NIST glasses and natural basaltic to rhyolitic glasses mainly in terms of their sputtering-induced fractionation of boron isotopes. As no matrix effect was found among basaltic to rhyolitic glasses, instrumental mass fractionation of most natural glass samples can be corrected by using appropriate glass reference materials. In order to confirm the existence of the compositionally induced variations in boron SIMS instrumental mass bias, the observed offset in SIMS instrumental mass bias has been independently reproduced in two laboratories and the phenomenon has been found to be stable over a period of more than one year. This study highlights the need for a close match between the chemical composition of the reference material and the samples being investigated. 相似文献
24.
The plane-wave reflection and transmission coefficients at a plane interface between two anisotropic media constitute the elements of the elastic scattering matrix. For a 1-D anisotropic medium the eigenvector decomposition of the system matrix of the transformed elasto-dynamic equations is used to derive a general expression for the scattering matrix. Depending on the normalization of the eigenvectors, the expressions give scattering coefficients for amplitudes or for vertical energy flux.Computing the vertical slownesses and the corresponding polarizations, the eigenvector matrix and its inverse can be found. We give a simple formula for the inverse, regardless of the normalization of the eigenvectors. When the eigenvectors are normalized with respect to amplitudes of displacement (or velocity), the calculation of the scattering matrix for amplitudes is simplified.When the relative changes in all parameters are small, a weak-contrast approximation of the scattering matrix, based on the exactly determined polarization vectors in an average medium, is obtained. The same approximation is also derived directly from the transformed elasto-dynamic equations for a smooth vertically inhomogeneous medium, proving the consistency of the approximation.For monoclinic media, with the mirror symmetry plane parallel to the interface, the approximative scattering matrix is given in terms of analytic expressions for the non-normalized eigenvectors and vertical slownesses. For transversely isotropic media with a vertical axis of symmetry (VTI) and isotropic media, explicit solutions for the weak-contrast approximations of the scattering matrices have been obtained. The scattering matrix for amplitudes for isotropic media is well known. The scattering matrix for vertical energy flux may have applications in AVO analysis and inversion due to the reciprocity of the reflection coefficients for converted waves.Numerical examples for monoclinic and VTI media provide good agreement between the approximative and the exact reflection matrices. It is, however, expected that the approximations cannot be used when the symmetry properties of the two media are very different. This is because the approximation relies on a small relative contrast between the eigenvectors in the two media.Presented at the Workshop Meeting on Seismic Waves in Laterally Inhomogeneous Media, Castle of Trest, Czech Republic, May 22–27, 1995. 相似文献
25.
Chang-Jo F. Chung 《Mathematical Geology》1993,25(7):851-865
Multivariate statistical analyses have been extensively applied to geochemical measurements to analyze and aid interpretation of the data. Estimation of the covariance matrix of multivariate observations is the first task in multivariate analysis. However, geochemical data for the rare elements, especially Ag, Au, and platinum-group elements, usually contain observations the below detection limits. In particular, Instrumental Neutron Activation Analysis (INAA) for the rare elements produces multilevel and possibly extremely high detection limits depending on the sample weight. Traditionally, in applying multivariate analysis to such incomplete data, the observations below detection limits are first substituted, for example, each observation below the detection limit is replaced by a certain percentage of that limit, and then the standard statistical computer packages or techniques are used to obtain the analysis of the data. If a number of samples with observations below detection limits is small, or the detection limits are relatively near zero, the results may be reasonable and most geological interpretations or conclusions are probably valid. In this paper, a new method is proposed to estimate the covariance matrix from a dataset containing observations below multilevel detection limits by using the marginal maximum likelihood estimation (MMLE) method. For each pair of variables, sayY andZ whose observations containing below detection limits, the proposed method consists of three steps: (i) for each variable separately obtaining the marginal MLE for the means and the variances,
,
,
, and
forY andZ: (ii) defining new variables by
and
and lettingA=C+D andB=C–D, and obtaining MLE for variances,
and
forA andB; (iii) estimating the correlation coefficient YZ by
and the covariance
YZ
by
. The procedure is illustrated by using a precious metal geochemical data set from the Fox River Sill, Manitoba, Canada. 相似文献
26.
功能—技术矩阵,经众多工作者的努力研究,已渐趋成熟与实用。但如何利用功能—技术矩阵构造在广义现代设计领域中适用的科学模式,解决多学科设计方案的组成与评价问题,还存在薄弱环节。本文利用“使用价值分析优化”的概念,从设计方案技术先进性和经济合理性的协调统一的角度出发,较好地实现了功能—技术矩阵可行优化组合链的组成与评价,弥补了以往的缺陷。 相似文献
27.
模糊理论在公路边坡稳定性分析中的应用 总被引:7,自引:0,他引:7
边坡工程是一个复杂的系统工程。边坡的稳定与否直接关系到其防护工作的程度。因此,如何有效、合理地判断边坡的稳定性对整个工程的经济与社会效益极为重要。影响边坡稳定的因素众多,判断其稳定与否应考虑各因素的综合效果。论文运用模糊理论中的多因素综合评判模型对某高速公路边坡的稳定性进行研究。通过全面考虑影响因素,建立相应的评判因素集及单因素评判矩阵,运用专家评判法和判断矩阵法确定出各因素的权重。最后通过多层次模糊评判得到该边坡的稳定性评判结果。研究证明,该法在边坡稳定性分析评判中是切实可行的。 相似文献
28.
粗差发现和定位能力与相关系数的关系 总被引:2,自引:0,他引:2
根据粗差判断方程中的判断矩阵和两个统计检验量之间相关系数的函数式,论证了两种不同的研究方法所确定的粗差不能定位的数学模型实际上是相等的。通过算例,不仅说明两种研究方法对观测量不能定位粗差的判断是一致的,而且使用判断矩阵研究观测量的粗差发现和定位能力会更加方便简单。 相似文献
29.
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