Statistical characteristics of geophysical fields in Hilbert's space     

Miloslav Burda  Vincenc Vyskočil  Reviewer L. Kubáčková 《Studia Geophysica et Geodaetica》1973,17(4):300-305

Summary A review of the terms of functional analysis, which can be exploited for statistical treatment of geophysical fields, is given. The procedure for determining the statistical characteristics of the fields, defined by a single realization, which does not require the limiting assumption of homogeneity to be introduced, is outlined.  相似文献   

Satellite measurements of solar X-ray flux and their use for interpretation of sudden ionospheric disturbances     

J. Laštovička  J. Šmilauer 《Pure and Applied Geophysics》1972,98(1):178-183

Summary The apparatus for the reception and evaluation of the real-time telemetry (RTT) data on the X-ray flux, measured by the satellite Solrad-9, is briefly described. A comparison of the RTT data obtained with the data published by the authors of the experiment shows a good correlation of the data compared. The results of the comparison of our RTT data with SID data of the Panská Ves Observatory confirm many known facts concerning the response of the lower ionosphere to solar flares and, moreover, seem to support the idea of a less important role of X-rays in the lower ionosphere under slightly disturbed conditions.  相似文献   

Über Konvergenzerscheinungen bei Standortsformen der Blaualgen unter extremen Lebensbedingungen     

Dr. S. Von Golubić  Dr. E. Marčenko 《Aquatic Sciences - Research Across Boundaries》1965,27(2):207-217

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Geomagnetisches Restfeld und die Frage Seines Zusammenhanges mit dem Bau der Erdkruste     

Alena Janáčková 《Studia Geophysica et Geodaetica》1964,8(1):45-62

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Analytical expression for fresnel volumes and interface fresnel zones of seismic body waves. Part 1: Direct and unconverted reflected waves     

Michal Kvasnička  Vlastislav Červený 《Studia Geophysica et Geodaetica》1996,40(2):136-155

Summary Fresnel volumes, plane-sectional Fresnel zones and interface Fresnel zones of direct and unconverted reflected waves are studied. Exact analytical expressions for various parameters of Fresnel volumes and Fresnel zones are derived and discussed. Among others, these expressions are related to semi-axes of Fresnel zones, to overshooting and penetration distances, and to the off-ray shifts of Fresnel zones.  相似文献   

Accuracy assessments of recent earth gravity models using crossover altimetry     

Jaroslav Klokočník  Carl A. Wagner  Jan Kostelecký 《Studia Geophysica et Geodaetica》1996,40(1):77-110

Summary The calibrated variance-covariance matrices of the harmonic geopotential coefficients of the recent combined model JGM 2 has been tested and verified by independent crossover altimetry from TOPEX/Poseidon and ERS 1 using the Latitude Lumped Coefficients in the southern oceans area. Although orbits are not yet available for these missions with other recent models for which error matrices have been released, by comparison with JGM 2 results and field differences we also confirm that the error matrices for the satellite model GRIM 4S4p and the combined data model JGM 3 are also generally valid. Projections of these matrices for a variety of inclinations show that many unused orbits of even moderate altitude (≈ 800 km) will still yield trajectory crossover errors at a level of many tens of centimeters even with the latest orbitgeopotential models.  相似文献   

Impedance spectroscopy and defect chemistry of fayalite     

Th. Barkmann  L. Cemič 《Physics and Chemistry of Minerals》1996,23(3):186-192

Impedance spectra of polycrystalline synthetic fayalite were measured at 900°C and 1 atm pressure in a CO/CO₂ gas mixing furnace at oxygen fugacities f _{O 2}=10^-13 to 10^-17 atm. The frequency range applied to the samples was 20 Hz–1 MHz. The spectra show two semicircular arcs, which are attributed to polarization processes within the bulk material and at the sample-electrode interface. Two different types of behaviour of the bulk resistance as a function of oxygen fugacity were observed. The first is proportional to the -1/4.5 to -1/6 power of f_{I 2}, which is consistent with the existing defect model. The second shows a lesser dependence on f_{O 2}, often lowered by a factor of about two, relative to the expected value, resulting in a resistance proportional to the -1/10 to -1/12 power of f_{O 2}. It is assumed, that the lesser f _{O 2}-dependence is caused by aliovalent impurities, producing an f_{O 2}-independent amount of charge carriers. The electrode arcs show a resistance proportional to the-1/2 to -1/4 power of oxygen fugacity, implying that a reaction with the gas phase is involved in the polarization process at the sample-electrode interface.  相似文献   

Downward continuation of Helmert's gravity     

P. Vaníček  W. Sun  P. Ong  Z. Martinec  M. Najafi  P. Vajda  B. ter Horst 《Journal of Geodesy》1996,71(1):21-34

. The aim of this contribution is to show that mean Helmert's gravity anomalies obtained at the earth surface on a grid of a `reasonable' step can be transferred to corresponding mean Helmert's anomalies on the geoid. To demonstrate this, we take the by mean Helmert's anomalies from a very rugged region, the south-western corner of Canada which contains the two main chains of the Canadian Rocky Mountains, and formulate the problem of downward continuation of Helmert's anomalies for this region. This can be done exactly because Helmert's disturbing potential is harmonic everywhere outside the geoid, therefore even within the topography. Then we solve the problem numerically by transforming the Poisson integral to a system of 53,856 linear algebraic equations. Since the matrix of this system is well conditioned, there is no theoretical obstacle to the solution. The correctness of the solution is then checked by back substitution and by evaluating the contribution of the downward continuation term to Helmert's co-geoid. This contribution comes out positive for all the points. We thus claim that the determination of the downward continuation of mean Helmert's gravity anomalies on a grid of a `reasonable' step is a well posed problem with a unique solution and can be done routinely to any accuracy desired in the geoid computaion. Received 27 October 1995; Accepted 9 July 1996  相似文献   

Transformation of coordinates between two horizontal geodetic datums   总被引：2，自引：1，他引：2  

Petr Vaníček  Robin R. Steeves 《Journal of Geodesy》1996,70(11):740-745

The following topics are discussed in this paper: the geocentric coordinate system and its different realizations used in geodetic practice; the definition of a horizontal geodetic datum (reference ellipsoid) and its positioning and orientation with respect to the geocentric coordinate system; positions on a horizontal datum and errors inherent in the process of positioning; and distortions of geodetic networks referred to a horizontal datum. The problem of determining transformation parameters between a horizontal datum and the geocentric coordinate system from known positions is then analysed. It is often found necessary to transform positions from one horizontal datum to another. These transformations are normally accomplished through the geocentric coordinate system and they include the transformation parameters of the two datums as well as the representation of the respective network distortions. Problems encountered in putting these transformations together are pointed out.  相似文献   

Comparison of in-situ Field Measurements of Soil Magnetic Susceptibility with Laboratory Data   总被引：1，自引：0，他引：1  

Kapička  Aleš  Petrovský  Eduard  Jordanova  Neli 《Studia Geophysica et Geodaetica》1997,41(4):391-395

Results of magnetic susceptibility mapping around a coal-burning power plant were used to verify the field in situ measurements with data acquired in laboratory on soil samples collected at approximately the same measurement grid sites at different distance from the source. This comparison enables quantifying the field data obtained using the Bartington MS2 meter and to relate them, at least approximately, to mass specific values. Moreover, it is shown that certain diversity in the grid points of field measurements and soil sampling can slightly bias the field measurements. However, this shift is of minor significance and Bartington field readings can be considered as reliable.  相似文献