A physical‐model study of the statistics of seismic waveform fluctuations in random heterogeneous media     

C. Sivaji  O. Nishizawa  G. Kitagawa  Y. Fukushima 《Geophysical Journal International》2002,148(3):575-595

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A new formalism for the effect of lateral heterogeneity on normal modes and surface waves—I: isotropic perturbations, perturbations of interfaces and gravitational perturbations     

Roel Snieder  Barbara Romanowicz 《Geophysical Journal International》1988,92(2):207-222

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基于GIS的兰州市普通住宅价格空间格局分析   总被引：8，自引：1，他引：8  

李传华  潘竟虎  赵军 《云南地理环境研究》2007,19(2):88-91

基于兰州市2005～2006普通住宅数据，利用空间分析中点模式分析，空间自相关分析，房价与区位因子的线性回归分析，空间插值方法等，对兰州市普通住宅价格的空间分布格局进行分析，并运用线性回归分析对其影响因素进行了探讨。研究表明，兰州市房地产发展在空间上具有明显的集聚特点，房价的空间自相关很明显，房价与商服中心的距离呈显著的线性相关性。空间分析方法提供了准确认识、评价和综合理解空间位置和空间相互作用的手段，为定量研究提供了支持。  相似文献   

Scattering physics     

J. O. Stenflo 《Solar physics》1996,164(1-2):1-20

The theory of polarized scattering in a stellar atmosphere is formulated, first within the framework of classical physics, then in terms of quantum mechanics. The expression for the redistribution matrix that describes partial redistribution in polarization and frequency is derived for the general case when the magnetic field is of arbitrary strength. The special cases of weak fields (the Hanle limit) and zero fields (non-magnetic scattering) are discussed. Observational examples of spectral signatures in linear polarization are presented, which show effects of hyperfine structure, interference between fine structure components, and molecular scattering.  相似文献   

STUDY OF PHYSICAL MECHANISM FOR ACTIVE AND BREAK PHASES OF SOUTH ASIAN MONSOON     

吴洪  王永中  夏友龙 《热带气象学报(英文版)》1998,4(2):122-130

Using a low-order spectral model derived from the equatorial equilibrium model, possible physical mechanisms are interpreted by the theory of multiple equilibria states for the active and break phases of the South Asian Monsoon, with consideration of the effects of heating by cumulus heating and cooling by radiation. The result shows that the South Asian Monsoon is active when the cumulus convection intensifies (or the radiation cooling weakens). the monsoon breaks when the convection weakens (or the cooling intensifies). It is consistent with the hypothesis of cloud-radiation by Krishnamurti et al.  相似文献   

Spatial Structure and Long-Term Variations of The Ground-Level Temperature Variance     

P.V. Kishcha  I.V. Dmitrieva 《Studia Geophysica et Geodaetica》1998,42(4):511-520

The global distribution of the ground-level temperature variance and its long-term variations have been investigated on the basis of the monthly mean temperature anomalies, obtained from ground-based and sea-borne meteorological observations from 1896 to 1990. Particular characteristics of the large-scale structure of the temperature variance have been found. There are three pronounced maxima in the global distribution of the temperature variance: in Central Siberia (60°75°N and 70° 120°E), North America (60°75°N and –170°–120°E) and the Antarctica (50°65°S and –60°10°E, where and are the geographic latitude and longitude, respectively) and there are two minima: over the Atlantic and Pacific Ocean areas. The minimum over the Pacific is not as pronounced, as over the Atlantic. The spatial pattern of the ground-level temperature variance is, on the whole, stable, the positions of the zones of extrema remaining practically unchanged over a long time interval. These results indirectly corroborate the mechanism of solar impact on the properties of the low atmosphere by the modulation of the flux of galactic cosmic rays. The mechanism accounts for the spatial distribution of the temperature variance as a result of combined effect of solar activity and ocean. Long-term variations of the Siberian maximum of the ground-level temperature variance agree with the changing duration of the sunspot cycle, in contrast to the North American maximum.  相似文献   

Distinguishing and correlating multiple phases of metamorphism across a multiply deformed region using the axes of spiral, staircase and sigmoidal inclusion trails in garnet   总被引：2，自引：0，他引：2  

T. H. BELL  K. A. HICKEY  & G. J. G. UPTON 《Journal of Metamorphic Geology》1998,16(6):767-794

Schists from the Appalachian Orogen in south-east Vermont have undergone multiple phases of garnet growth. These phases can be distinguished by the trend and relative timing of f oliation i nflexion or i ntersection a xes (FIAs) of foliations preserved as inclusion trails in garnet porphyroblasts. The relative timing of different generations of FIAs is determined from samples containing porphyroblasts with two or three differently trending FIAs developed outwards from core to rim (multi-FIA porphyroblasts). Schists from south-east Vermont show a consistent pattern of relative clockwise rotation of FIA trends from oldest to youngest. Four populations or sets of FIAs can be distinguished on the basis of their relative timings and trends. From oldest to youngest, the four sets have modal peaks trending SW–NE, W–E, NNW–SSE and SSW–NNE. These peaks show that each of the four FIA sets has a statistically consistent trend at all scales across a 35×125 km area containing numerous mesoscopic and macroscopic folds. The FIAs of Set 4 are defined by inclusion trails that are continuous with matrix foliations, have trends subparallel to most folds and are inferred to have developed contemporaneously with these structures. Conversely, Sets 1 to 3 are oblique to and pre-date most matrix foliations and folds. All four FIA sets occur in Siluro-Devonian rocks and must have formed in the Acadian Orogeny. The lack of statistically significant differences in the distribution of FIA trends across the study area and their consistent relative timings in multi-FIA porphyroblasts, despite a complex regional deformation history involving numerous phases of folding at all scales, suggest the porphyroblasts have not rotated relative to one another. The change in FIA trend with time resulted from rotation of the kinematic reference frame of bulk flow, possibly as a consequence of the reorganization of lithospheric plates responsible for Acadian orogenesis. Recognition of distinct generations of FIAs provides a means of distinguishing different phases of porphyroblast growth. Four periods of garnet porphyroblast growth occurred in the schists of south-east Vermont. This growth was heterogeneously distributed on the cm²–m² scale. No single porphyroblast records all stages of growth, and adjacent samples from the same or dissimilar rock types commonly contain porphyroblasts that preserve different sequences of growth. Factors that may have been responsible for switching porphyroblast growth on and off at this scale include: (i) subtle differences in bulk chemical composition; (ii) oscillating levels of heat, owing to the buffering effect of endothermic garnet-forming reactions; (iii) channelized infiltration of fluids with localized fluid buffering of bulk composition; and (iv) cyclic controls on the rates of diffusion and material transport of reactants, either by channelized fluid flow or by a changing pattern of microfracturing during foliation development. Consistency in FIA trend and relative timing provide a new method for potentially distinguishing and correlating successive metamorphic events, or even phases of metamorphism within a progressive tectonothermal event, along and across orogens. Using a consistent pattern of core to rim changes in FIA trend, multiple phases of growth of a single porphyroblastic mineral can be quantitatively distinguished, allowing correlation of different phases of growth around and across macroscopic folds. The relative timing of growth of different porphyroblastic minerals can also be quantitatively determined using FIA data and correlated around and across macroscopic folds. Conceptually, the paragenetic history preserved in each generation of porphyroblast growth, in the form of chemical zoning and the minerals in inclusion trails, could be combined to produce a more detailed P–T–t–deformation path than previously determined.  相似文献   

Bidirectional Reflectance of Gaussian Random Surfaces and Its Scaling Properties     

Daniela Despan  Ali Bedidi  Bernard Cervelle  Jean-Paul Rudant 《Mathematical Geology》1998,30(7):873-888

Using rigorous probabilistic techniques we define and compute the shadowing factor, the conditional mean slope and the conditional standard deviation of the slope for a random rough surface described as an isotropic Gaussian stochastic process with Gaussian autocorrelation function. We use these quantities in order to obtain the bidirectional reflectance distribution function for incoherent light scattering by rough surfaces. The calculated quantities depend on reduced, affine invariant parameters, such that changing roughness is equivalent to rescaling the slopes of incident and emergent direction. We discuss some possible applications of these scaling properties to remote sensing.  相似文献   

Application of Correspondence Analysis in the Assessment of Groundwater Chemistry   总被引：1，自引：0，他引：1  

Fernando António Leal Pacheco 《Mathematical Geology》1998,30(2):129-161

Correspondence Analysis (CA) was used to determine the sources and processes that may explain the variation observed in datasets of groundwater analyses. The following method was adopted: (1) based on the observation of sympathies and antipathies between loadings signs, correspondence factors were represented by parameters with some pertinent geochemical meaning: (2) the relation between factors and parameters then was checked by Multiple Linear Regression (MLR) where factors acted as independent variables and parameters as dependent variables. Sample scores of the selected parameters gave the ability to separate polluted from nonpolluted waters, identify areas where pollution is dominated by agriculture and areas where contamination is controlled by domestic effluents, and describe weathering and agricultural activities in the sampled area. The practical example presented here anticipates the impact of agriculture and urban pollution on the chemistry of 160 water samples collected in a granitoid area at central Portugal (Fundão).  相似文献   

The fast multipole method for integral equations of seismic scattering problems     

Hiroyuki Fujiwara 《Geophysical Journal International》1998,133(3):773-782

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