Revised exponential distance relation for the Uranian system after the Voyager 2 fly-by     

Vladimir Pletser 《Earth, Moon, and Planets》1988,41(3):295-300

The rings and satellites discovered by Voyager 2 in the Uranian system confirm the existence of small satellites and rings foreseen before their discoveries and close to the locations suggested by an exponential distance relation found by the method of comparison of magnitude order of successive distances ratios of the large Uranian satellites. A new exponential distance relation is deduced, fitting the distances of the large satellites and groups of rings and new small satellites with a spacing ratio of 1.456. Some characteristics of an hypothetical parent body for the new inner satellites are also deduced.  相似文献   

Far Ultraviolet Spectrum of Mars     

Vladimir A. KrasnopolskyPaul D. Feldman 《Icarus》2002,160(1):86-94

A spectrum of Mars of unprecedented quality was obtained in the range of 904-1183 Å with a spectral resolution of 0.2 Å using the Far Ultraviolet Spectroscopic Explorer. Besides marking the first detection of molecular hydrogen on Mars (Krasnopolsky and Feldman, Science 2001 294, 1914-1917), the spectrum also revealed many emission lines of H, O, N, C, Ar, He, N⁺, C⁺, and Ar⁺ and the bands of N₂ and CO. The spectrum makes it possible to study the emission multiplet structures and the component ratios and to separate many of the blended lines. From the argon lines, we retrieved Ar mixing ratios of 1.5 and 1.3% at 150 and 130 km, respectively, in excellent agreement with the Viking mass spectrometric measurements of 1.6% in the lower atmosphere. The He 584-Å emission observed in second order also agrees with the Extreme Ultraviolet Explorer detection of He on Mars. The observed spectrum may be used as a database to study specific problems such as the dayglow excitation, radiative transfer, and composition in Mars' upper atmosphere.  相似文献   

A new scheme for numerical modelling of flow and transport processes in 3D fractured porous media     

Andrés Peratta  Viktor Popov 《Advances in water resources》2006

The objective of this work is to develop a new numerical approach for the three-dimensional modelling of flow and transient solute transport in fractured porous media which would provide an accurate and efficient treatment of 3D complex geometries and inhomogeneities. For this reason, and in order to eliminate as much as possible the number of degrees of freedom, the fracture network, fractures and their intersections, are solved with a coupled 2D–1D model while the porous matrix is solved independently with a 3D model. The interaction between both models is accounted for by a coupling iterative technique. In this way it is possible to improve efficiency and reduce CPU usage by avoiding 3D mesh refinements of the fractures. The approach is based on the discrete-fracture model in which the exact geometry and location of each fracture in the network must be provided as an input. The formulation is based on a multidimensional coupling of the boundary element method-multidomain (BEM-MD) scheme for the flow and boundary element dual reciprocity method-multidomain (BE-DRM-MD) scheme for the transport. Accurate results and high efficiency have been obtained and are reported in this paper.  相似文献   

Determination of Porosity and Permeability out of Dispersion Analyses of Borehole Wall Displacements     

Michael Albrecht  Vladimir Mansurov 《Pure and Applied Geophysics》2006,163(10):2125-2140

Waves carried in the borehole can be measured by the use of controlled sources inside the borehole and receivers located in the same borehole as well. This article gives the theoretical background and develops a new method to determine rock-physical parameters out of such controlled measurements of waves carried inside the borehole. Theoretical dispersion curves of the group velocities are matched to dispersion analyses of registrations obtained in the borehole. This inversion process intends to determine the in situ porosity and permeability of the rock.  相似文献   

Application of laser strainmenters to the study of earthquake physics     

Grigory I. Dolgikh  Mstislav N. Dubrov  Stanislav G. Dolgikh  Sergei N. Kovalev  Vladimir V. Ovcharenko  Egor A. Savvin  Vladimir A. Chupin  Vyacheslav A. Shvets  Sergei V. Yakovenko 《Acta Geophysica》2006,54(2):187-197

The paper considers possibilities of applying laser strainmeters for the study of earthquake physics. One of laser strainmeters is described. A high efficiency of using the laser strainmeters for the study of earthquakes and their precursors is shown. In records of the spaced laser strainmeters, anomalous deformations propagating from the east to the west with the speed comparable with that of migration of earthquakes were found.  相似文献   

Spectral scaling in Mars topography: effect of craters     

Vladimir Nikora  Derek Goring 《Acta Geophysica》2006,54(1):102-112

Extensive computer simulations aimed at testing a hypothesis that impact craters may explain the scaling behaviour of surface spectra are presented. The simulations show that indeed crater effects alone may explain the spectral scaling of Mars’ topography revealed from MOLA data. The range of the scaling exponents obtained for a wide range of simulation parameters does not exceed the limits observed for Mars. The simulations suggest that the shape of large craters is the key factor leading to the two scaling ranges in the surface spectra. Particular values of the scaling exponents may additionally depend on the depth-diameter relationship and the crater size distribution.  相似文献   

Bianchi-II Rotating World     

Vladimir A. Korotky  Yuri N. Obukhov 《Astrophysics and Space Science》1998,260(4):425-439

Dynamical and kinematic properties of Bianchi-II cosmological models with rotation and expansion are investigated. Exact solutions of Einstein field equations are obtained which describe the evolution of a rotating Universe. Exact solutions of null, timelike and spacelike geodesics are constructed. Two new cosmological tests for rotating universes are discussed: cosmological lens effect and cosmological mirror effect.  相似文献   

Dynamical Properties of a Sample of Ellipticals     

Vladimir Garrido Ortega  Gladys Lopes Vieira  J.A. de Freitas Pacheco 《Astrophysics and Space Science》1998,262(3):271-295

On the basis of Jeans equations we study some dynamical properties of a sample of E galaxies considered as oblate and prolate spheroids. Although the results emphasize the anisotropy as the dominant dynamical factor both for oblate and prolate configurations, the sample contains some oblate galaxies apparently isotropic consistent with full rotational support. Comparisons of the mass-to-luminosity ratios obtained from our models with ratios derived from recent evolutionary synthesis models do not seem to leave room for nonluminous matter within the ranges (of the order of one de Vaucouleurs' radius) of the kinematical observations. Such comparisons suggest that a flatter than the classical Salpeter IMF would lead to better agreement with the dynamical results obtained within the framework of our models.  相似文献   

Isoseismals of the strongest Friuli aftershocks of September 1976     

Vít Kárník  Dana Procházková  Zdeňka Schenková  Julius Drimmel  Dieter Mayer-Rosa  Dragutin Cvijanovic  Vladimir Kuk  Andelka Miloševič  Francesco Giorgetti  Reviewer J. Janský 《Studia Geophysica et Geodaetica》1978,22(4):411-414

Summary Isoseismal maps of the three strongest Friuli aftershocks of September 1976 were compiled using the contributions from European countries within the shaken area. The characteristic features of the macroseismic fields are discussed.  相似文献   

Barents Sea upstream events impact the properties of Atlantic water inflow into the Arctic Ocean: Evidence from 2005 to 2006 downstream observations     

Igor A. Dmitrenko  Dorothea Bauch  Sergey A. Kirillov  Nikolay Koldunov  Peter J. Minnett  Vladimir V. Ivanov  Jens A. Hölemann  Leonid A. Timokhov 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(4):513-527

Inflow of Atlantic water (AW) from Fram Strait and the Barents Sea into the Arctic Ocean conditions the intermediate (100–1000 m) waters of the Arctic Ocean Eurasian margins. While over the Siberian margin the Fram Strait AW branch (FSBW) has exhibited continuous dramatic warming beginning in 2004, the tendency of the Barents Sea AW branch (BSBW) has remained poorly known. Here we document the contrary cooling tendency of the BSBW through the analysis of observational data collected from the icebreaker Kapitan Dranitsyn over the continental slope of the Eurasian Basin in 2005 and 2006. The CTD data from the R.V. Polarstern cruise in 1995 were used as a reference point for evaluating external atmospheric and sea-ice forcing and oxygen isotope analysis. Our data show that in 2006 the BSBW core was saltier (by ～0.037), cooler (by ～0.41 °C), denser (by ～0.04 kg/m³), deeper (by 150–200 m), and relatively better ventilated (by 7–8 μmol/kg of dissolved oxygen, or by 1.1–1.7% of saturation) compared with 2005. We hypothesize that the shift of the meridional wind from off-shore to on-shore direction during the BSBW translation through the Barents and northern Kara seas results in longer surface residence time for the BSBW sampled in 2006 compared with samples from 2005. The cooler, more saline, and better-ventilated BSBW sampled in 2006 may result from longer upstream translation through the Barents and northern Kara seas where the BSBW was modified by sea-ice formation and interaction with atmosphere. The data for stable oxygen isotopes from 1995 and 2006 reveals amplified brine modification of the BSBW core sampled downstream in 2006, which supports the assumption of an increased upstream residence time as indicated by wind patterns and dissolved oxygen values.  相似文献