Electromagnetic induction of a three-dimensional conductivity inhomogeneity in the two-layered earth     

Milan Hvoždara  Reviewer V. Petr 《Studia Geophysica et Geodaetica》1981,25(2):167-180

Summary The calculation of the elements of Green's tensor function is presented for solving the problem of the electromagnetic induction by means of a vector integral equation. A two-layered Earth is considered as the medium, the surface layer including a three-dimensional conductivity inhomogeneity. Use is made of the boundary condition requiring the vertical component of the electric current to be zero at the Earth's surface which partly simplifies the theoretical computation. Long-period asymptotics of the individual complicated functions, occurring in Green's tensor function as well as in the tensor function required to calculate the components of the anomalous magnetic field at the surface of the halfspace, were effected. With the aid of these asymptotics one can obtain estimates of the functions occurring in the theoretical analysis of the problem.  相似文献   

To the problem of noise reduction in sea-level records used in vertical crustal movement detection     

Petr Vaníček 《Physics of the Earth and Planetary Interiors》1978,17(3):265-280

The aim of this investigation is to develop a simple technique that would allow us to use the sea-level records for detecting contemporary vertical crustal movements of duration from several months to several years. The choice of auxiliary data needed for any such analysis is restricted to the regularly available meteorological data to make this approach possible in routine search for precursory movements in earthquake-prone areas. A linear mathematical model is designed to evaluate the effect of atmospheric temperature and pressure variations, river discharge, long periodic tides and Chandlerian motion. Spectra of the residual sea-level variations are also shown. It is concluded that local episodic crustal movements of a magnitude larger than some 10 cm may be detectable by this approach. If finer resolution is needed then it it necessary to also account for steric level, wind, and sea-current variations, for which data are largely non-existent.  相似文献   

Electromagnetic induction study on dss profile No. V (carpathians)     

Jerzy Jankowski  Antoni Szymański  Jana Pěčová  Oldřich Praus  Václav Petr  Reviewer A. Janáčková 《Studia Geophysica et Geodaetica》1975,19(1):95-102

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Tensor structure and the least squares     

Petr Vaníček 《Journal of Geodesy》1979,53(3):221-225

It is shown that for linear parametric adjustment models all the least-squares equations can be obtained from a commutative diagram, where the observation and parameter spaces are regarded as covariant. Their contravariant counterparts are defined through the metric property of the covariance matrix of the observations.  相似文献   

Electromagnetic induction in a spherical earth with a circular bulge in the upper mantle     

Milan Hvoždara  Reviewer V. Petr 《Studia Geophysica et Geodaetica》1977,21(3-4):374-382

Summary Results of computing the anomalies of the variable magnetic field, generated by a harmonically variable field of the H_1,0-type in the model of a spherical Earth with an expressive bulge in the well-conducting part of the mantle, are presented. It was found that not only the radial, but also the tangential component of the magnetic field is disturbed above the bulge. The largest amplitudes of these changes can be observed over the area of the largest slope of the conductivity boundary if the exciting magnetic field is perpendicular to the surface of the interface.  相似文献   

Excess europium content in precambrian sedimentary rocks and continental evolution     

Petr Jakeš  S.R Taylor 《Geochimica et cosmochimica acta》1974,38(5):739-745

We propose that the europium excess in Precambrian sedimentary rocks, relative to those of younger age is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a grandioritic upper crust by partial melting in the lower crust, which selectively retains europium.  相似文献   

Seven Asteroids Studied from Modra Observatory in the Course of Binary Asteroid Photometric Campaign     

Adrián Galád  Petr Pravec  Štefan Gajdoš  Leonard Kornoš  Jozef Világi 《Earth, Moon, and Planets》2007,101(1-2):17-25

We report lightcurves for five asteroids from the inner main belt—(1703) Barry, (2590) Mourão, (4022) Nonna, (5171) Augustesen, (23031) 1999 XX₇—and for two near-Earth asteroids—(100004) 1983 VA, (144922) 2005 CK₃₈—obtained at Modra Observatory as a part of binary asteroid photometric campaign. Estimated synodic rotational periods and amplitudes of their composite lightcurves were as follows: 107.1 ± 0.5 h, 0.5 mag for (1703) Barry; 15.59 ± 0.01 h, 0.49 mag for (2590) Mourão; 2.5877 ± 0.0005 h, 0.08 mag for (4022) Nonna; 474 ± 10 h, 0.8 mag for (5171) Augustesen; 3.075 ± 0.001 h, 0.43 mag for (23031) 1999 XX₇; 3.1643 ± 0.0009 h, 0.11 mag for (100004) 1983 VA; 4.7894 ± 0.0005 h, 0.27 mag for (144922) 2005 CK₃₈. The slow rotator (5171) Augustesen and possibly also (1703) Barry appear to be tumblers, though their precession periods can not be estimated from the available data.  相似文献   

Robotic telescopes for high energy astrophysics in Ondřejov     

Martin Nekola  René Hudec  Martin Jelínek  Matůš Kocka  Petr Kubánek  Filip Münz  Cyril Polášek  Vojtěch Šimon  Jan Štrobl 《Experimental Astronomy》2010,28(1):79-85

We report on two small aperture robotic telescopes called BART and D50 operated in Ondřejov. Both telescopes are capable of automatic observation of gamma ray burst (GRB) optical afterglows. Coordinates of GRBs are taken from alerts distributed via Internet. Telescopes observe other interesting high energy sources when there is not any alert. The smaller telescope BART has aperture D = 254 mm. The bigger telescope D50 has a primary mirror of diameter D = 500 mm. Both telescopes are controlled by free software package RTS2 and are accessible through Internet. We describe the two telescopes and related software and show some results such as our first observed optical counterpart of GRB.  相似文献   

Expression of heat shock protein 70 in a permanent cell line (EPC) exposed to sediment extracts from the North Sea and the Baltic Sea     

Kinder A  Sierts-Herrmann A  Biselli S  Heinzel N  Hühnerfuss H  Kammann U  Reineke N  Theobald N  Steinhart H 《Marine environmental research》2007,63(5):506-515

Heat shock proteins 70 (hsp70) are known to be induced by a great variety of chemical stressors. The effects of different environmental contaminants, which were identified in sediments of the North Sea and the Baltic Sea as main contaminants or as contaminants of special toxicological interest, on the extent of expression of hsp70 in a permanent cell line Epithelioma papulosum cyprini (EPC) were investigated. Concentrations of the single contaminants leading to elevated hsp70 levels were compared to the respective concentrations of these contaminants encountered in the sediment extracts thus allowing an assessment of their contribution to the toxicity of these sediments. Analysis of hsp70 was performed using western blotting techniques with subsequent comparative quantification by densitometry. Eleven of thirteen contaminants have shown a dose-dependent increase in hsp70 levels. An expression of hsp70 was observed in most cases between 0.1 and 10 microg/mL test solution. Some of the investigated stressors led to extremely high hsp70 contents even at low concentrations. However, in most cases contaminant concentrations in sediments were too low to cause an effect. For this reason, effects of the tested sediments are attributed to other contaminants or rather to mixtures of stressors.  相似文献   

The reconstruction of a glacial lake outburst flood using HEC-RAS and its significance for future hazard assessments: an example from Lake 513 in the Cordillera Blanca,Peru   总被引：1，自引：0，他引：1  

Jan Klimeš  Miroslava Benešová  Vít Vilímek  Petr Bouška  Alejo Cochachin Rapre 《Natural Hazards》2014,71(3):1617-1638

In April 2010, an ice/rockfall into Lake 513 triggered a glacial lake outburst flood (GLOF) along the Chucchun River in the Cordillera Blanca of Peru. This paper reconstructs the hydrological characteristics of this as yet undocumented event using a 1D flood model prepared with HEC-RAS. The principle model inputs were obtained during detailed field surveys of surface characteristics and topography within the river and across the adjacent floodplain; a total of 120 cross-sections were surveyed. These inputs were refined further by eyewitness accounts and additional geomorphological observations. The flood modelling has enabled us to constrain the extent of the water surface and its elevation at each cross-section in addition to defining the peak discharge (580 m³ s^?1). These modelling results show good agreement with other information about the flood including: flood marks and minimum flood levels; the lake displacement wave height; the extent of the flooded area; and the travel time from Lake 513 to the confluence with the Santa River. This demonstrates that the model offers a reliable reconstruction of the basic hydrological characteristics of the GLOF. It provides important information about the flood intensity and significantly improves our ability to model future flood scenarios along both the studied river and within neighbouring catchments. The flood hazard, defined by the flood depth during peak discharge, shows that the majority of the damaged infrastructure (houses, bridges, and a drinking water treatment plant) was only subjected to low or medium flood intensities (defined by a maximum water depth of less than 2 m). These low flood intensities help to explain why the flooding caused comparatively minor damage despite the significant public attention it attracted.  相似文献