Analysis and Estimation of Natural Processes with Nonhomogeneous Spatial Variation Using Secondary Information   总被引：1，自引：0，他引：1  

Giorgio Cassiani  George Christakos 《Mathematical Geology》1998,30(1):57-76

Natural processes encountered in mining, hydrogeologic, environmental, etc. applications usually are poorly known because of scarcity of data over the area of interest. Therefore, stochastic estimation techniques are the tool of choice for a careful accounting of the heterogeneity and uncertainty involved. Within such a framework, a better utilization of all available data concerning the process of interest and all other natural processes related to it, is of primary importance. Because many natural processes show complicated spatial trends, the hypothesis of spatial homogeneity cannot be invoked always, and the more general theory of intrinsic spatial random fields should be employed. Efficient use of secondary information in terms of the intrinsic model requires that suitable permissibility criteria for the generalized covariances and cross-covariances are satisfied. A set of permissibility criteria are presented for the situation of two intrinsic random fields. These criteria are more general and comprehensive than the ones currently available in the geostatistical literature. A constrained least-square technique is implemented for the inference of the generalized covariance and cross-covariance parameters, and a synthetic example is used to illustrate the methodology. The numerical results show that the use of secondary information can lead to significant reductions in the estimation errors.  相似文献   

Incorporating Auxiliary Geophysical Data into Ground-Water Flow Parameter Estimation   总被引：1，自引：0，他引：1  

Giorgio Cassiani  Miguel A. Medina  Jr. 《Ground water》1997,35(1):79-91

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Sodar retrieval of vertical acceleration, and implications for the determination of temperature and fluxes in the convective boundary layer     

Giorgio Fiocco  Maria Grazia Ciminelli  Giangiuseppe Mastrantonio 《Atmospheric Research》1986,20(2-4)

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Comment on “analysis of nonintrinsic spatial variability by residual kriging with application to regional groundwater levels” by Shlomo P. Neuman and Elizabeth A. Jacobson     

Giuseppe Gambolati  Giorgio Galeati 《Mathematical Geosciences》1987,19(3):249-257

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Die Eigenschwingungen der durch den Kanal im Damm von Melide gekoppelten Becken des Luganersees     

Jürg Trösch  Giorgio Salvadè  Kurt Stocker 《Aquatic Sciences - Research Across Boundaries》1987,49(1):16-28

The northern and the southern basin of Lake Lugano, Switzerland, are separated by an artificial dam. The flow of the water is not only influenced by the outflow of the northern basin but also by gravitational oscillations (seiches) of both basins. A longperiodic peak around 100 minutes can be explained by a mathematical model. The interaction of the internal waves is a coupled oscillation with a period of 74 hours.   相似文献   

Crystal chemical variations in Ba-rich biotites from gabbroic rocks of lower crust (Ivrea Zone,NW Italy)     

Simona Bigi  Maria Franca Brigatti  Maurizio Mazzuchelli  Giorgio Rivalenti 《Contributions to Mineralogy and Petrology》1993,113(1):87-99

Biotites from mafic rocks occurring at different stratigraphic levels of the Ivrea-Verbano Mafic Complex are studied. The rocks are gabbros and diorites. All the biotites are intermediate between phlogopite and annite [0.282 (up to 7.14 and 9.32 wt%, respectively) with respect to those of the diorites (up to 1.26 and 6.26 wt%, respectively). Systematic compositional variations support the substitution model 2 ^IV Si+( ^IV R²⁺)2 ^IV Al+ ^VI Ti (R²⁺=Fe+Mg+Mn) in gabbros and ^IV Si+ ^VI Al ^IV Al+ ^VI Ti in diorites. A predominance of disordered stacking sequences, coexisting with 1M, 2M ₁ and 3T polytypes was observed in all biotites. It was possible to carry out structural refinements only on three biotites-2M ₁ from diorites (R-values between 2.68 and 3.77) and one biotite-1M from gabbros (R-value=3.09). It was shown that: (1) the reduced thickness of the tetrahedral sheet in Ba-rich biotites supports the coupled substitution ^IV Si+ ^XII K ^IV Al+ ^XII Ba; (2) the interlayer site geometry is affected by the whole layer chemistry and does not reflect only local chemical variations; (3) in two samples of the 2M ₁ polytype, the M(1) octahedral site is larger and more distorted than the M(2) sites because of the preferential ordering of Fe²⁺ in the M(1) site, whereas one sample shows complete cation disorder in the octahedral sites. Biotite-1M shows that Fe²⁺ can also be located in the M(2) site. Some of the differences between the biotites of gabbros and diorites (e.g. Ba concentration and exchange vectors) may be linked to the host rock composition and to its crystallization process. Biotite occurs in trace amounts in gabbros and its crystallization is related to the interstitial melt which contributed to the adcumulus growth of the main rock forming phases and became highly enriched in K, Ba and Ti. Diorites are the result of equilibrium crystallization of a residual melt rich in incompatible elements, where biotite is a major constituent.  相似文献   

Intercomparison of Boron Isotope and Concentration Measurements. Part I: Selection, Preparation and Homogeneity Tests of the Intercomparison Materials   总被引：4，自引：0，他引：4  

Sonia Tonarini  Maddalena Pennisi  Alessandra Adorni-Braccesi  rea Dini  Giorgio Ferrara  Roberto Gonfiantini  Michael Wiedenbeck  Manfred Gröning 《Geostandards and Geoanalytical Research》2003,27(1):21-39

In 1999 the Istituto di Geoscienze e Georisorse (IGG), with the support of the International Atomic Energy Agency (IAEA), undertook the collection, preparation and distribution of eight geological materials intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials came from Italian sources and consist of three natural waters (Mediterranean seawater and two groundwaters) and five rocks and minerals (tourmaline, basalt, obsidian, limestone and clay). The solid materials were crushed, milled and mixed, in preparation for distribution. Extensive assays performed at the IGG on these materials demonstrated that their boron isotopic and chemical compositions are homogeneous.
Additional homogeneity tests were carried out on solid material fragments at the GeoForschungsZentrum Potsdam, with the specific objective of investigating the suitability of some of them for the calibration in situ of micro-analytical techniques. Two materials, B4 (tourmaline) and B6 (obsidian), proved to be isotopically homogeneous and may become excellent references for in situ microanalyses of boron isotopes.
The materials described here were used as the basis of a major laboratory intercomparison study and are now available for further distribution from either the IAEA (solid materials) or the IGG (waters).  相似文献   

Extensional shear zones as imaged by reflection seismic lines: the Larderello geothermal field (central Italy)     

Andrea Brogi  Antonio Lazzarotto  Domenico Liotta  Giorgio Ranalli 《Tectonophysics》2003,363(1-2):127-139

The Larderello geothermal field is located in the Inner Northern Apennines, in an area which has been subject to extension since the Early Miocene. The latest extensional episode (Pliocene–Present) has resulted in the formation of NW-trending, NE-dipping listric normal faults, whose geometry is controlled down to 3 km by borehole data. In this paper, we integrate a new interpretation of seismic reflection lines with existing seismic, field, and borehole data to analyse the relations among listric normal faults, the top of the brittle–ductile transition, and the migration of geothermal fluids.In accordance with previous interpretations, we consider the strong reflector (K-horizon) marking the top of the reflective mid-lower crust, and located at a depth of 3–5 km in the geothermal area, to represent the top of the brittle–ductile transition. Its reflectivity most probably derives from the presence of overpressured fluids. We identify three main NW-trending, NE-dipping extensional brittle shear zones, showing listric geometry and soling out in the vicinity of the K-horizon. The latter appears to be dislocated in correspondence of the soling out of the shear zones. These shear zones, because of the associated intense fracturing, represent the most natural channels of upward migration of geothermal fluids from the magmatic sources located below the K-horizon.We suggest that these two conclusions—that listric normal faults root at or near the brittle–ductile transition, and that they act as preferential upward migration paths for magmatic fluids—may be of general validity for geothermal fields located in extensional settings.  相似文献   

Analogue modelling of the influence of shape and particle/matrix interface lubrication on the rotational behaviour of rigid particles in simple shear   总被引：1，自引：0，他引：1  

Stefano Ceriani  Neil S. Mancktelow  Giorgio Pennacchioni 《Journal of Structural Geology》2003,25(12):2005-2021

The rotational behaviour of a rigid particle embedded in a linear viscous matrix undergoing cylindrical simple shear (Couette) flow was studied in 2D rock-analogue experiments. The influence of particle shape (elliptical vs. monoclinic), aspect ratio and the nature of the matrix/particle interface (lubricated vs. unlubricated) was investigated. Both matrix (PDMS) and lubricant (liquid soap) were linear viscous, with a viscosity ratio of ca. 10⁴. Without lubricant, the rotational behaviour of all particles closely approximates the Jeffery theory. Lubricated monoclinic particles with the long diagonal initially parallel to the shear direction show back rotation and approach a stable position. Lubricated elliptical particles initially parallel to the shear direction also show back rotation but only transiently stabilize. Weak planar zones in the matrix adjacent to unlubricated elliptical particles do not induce backward rotation. In general for elliptical particles, rotation rate as a function of orientation depends on axial ratio and thickness of the lubricant mantle. For thick mantles (initially >10% of the volume of the particle), rotation rates are faster than Jeffery theory. For very thin mantles they are markedly slower compared with thick mantles, particularly when the long axis is nearly parallel to the shear direction. Rotation rates are never strictly zero, so true stabilization does not occur. However, for more elongate particles (axial RATIO=6) rotation rates are so slow that a very strong shape preferred orientation would develop in a lubricated elliptical particle population. In experiments, the volume of lubricant is constant and the thickness adjacent to the long side of the particle progressively decreases with increasing strain. In natural examples of porphyroclast systems, the weak mantle continually develops by recrystallization and/or cataclasis of the rigid clast core and a steady state between production and thinning could be attained, potentially leading to true stabilization for particles with a high axial ratio.  相似文献   

Nekhoroshev estimate for isochronous non resonant symplectic maps     

Armando Bazzani  Stefano Marmi  Giorgio Turchetti 《Celestial Mechanics and Dynamical Astronomy》1989,47(4):333-359

We prove that non resonant isochronous symplectic maps in a neighborhood of an elliptic fixed point are stable for exponentially long times with the inverse of the distance from the fixed point. In the proof we make use of the majorant series method together with an idea for optimizing remainder estimates first applied to Hamiltonian problems by Nekhoroshev.  相似文献