U-Pb zircon age of diorites of the Chusovsk Gabbrodiorite Series of the Verkhisetsk Massif (Middle Urals)     

E. A. Zinkova  G. B. Fershtater  N. V. Rodionov 《Doklady Earth Sciences》2009,425(1):239-242

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Tracking volcanic sulfur dioxide clouds for aviation hazard mitigation     

Simon A. Carn  Arlin J. Krueger  Nickolay A. Krotkov  Kai Yang  Keith Evans 《Natural Hazards》2009,51(2):325-343

Satellite measurements of volcanic sulfur dioxide (SO₂) emissions can provide critical information for aviation hazard mitigation, particularly when ash detection techniques fail. Recent developments in space-based SO₂ monitoring are discussed, focusing on daily, global ultraviolet (UV) measurements by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. OMI’s high sensitivity to SO₂ permits long-range tracking of volcanic clouds in the upper troposphere and lower stratosphere (UTLS) and accurate mapping of their perimeters to facilitate avoidance. Examples from 2006 to 2007 include eruptions of Soufriere Hills (Montserrat), Rabaul (Papua New Guinea), Nyamuragira (DR Congo), and Jebel at Tair (Yemen). A tendency for some volcanic clouds to occupy the jet stream suggests an increased threat to aircraft that exploit this phenomenon. Synergy between NASA A-Train sensors such as OMI and the Atmospheric Infrared Sounder (AIRS) on the Aqua satellite can provide critical information on volcanic cloud altitude. OMI and AIRS SO₂ data products are being produced in near real-time for distribution to Volcanic Ash Advisory Centers (VAACs) via a NOAA website. Operational issues arising from these improved SO₂ measurements include the reliability of SO₂ as proxy for co-erupted ash, the duration of VAAC advisories for long-lived volcanic clouds, and the potential effects of elevated concentrations of SO₂ and sulfate aerosol in ash-poor clouds on aircraft and avionics (including cumulative effects after multiple inadvertent transits through dilute clouds). Further research is required in these areas. Aviation community assistance is sought through continued reporting of sulfurous odors or other indications of diffuse volcanic cloud encounters, in order to validate the satellite retrievals.  相似文献   

New zircon ages on the Cambrian–Ordovician volcanism of the Southern Gemericum basement (Western Carpathians,Slovakia): SHRIMP dating,geochemistry and provenance     

Vozárová  Anna  Rodionov  Nickolay  Šarinová  Katarína  Presnyakov  Sergey 《International Journal of Earth Sciences》2017,106(6):2147-2170

International Journal of Earth Sciences - The Southern Gemericum basement in the Inner Western Carpathians, composed of low-grade volcano-sedimentary rock complexes, constitutes a record of the...  相似文献   

Early cretaceous cortlandite-pyroxenite-gabbro association of the Upper Amur region: Geochronological and geochemical data     

V. E. Strikha  V. A. Stepanov  N. I. Rodionov 《Doklady Earth Sciences》2006,407(3):469-473

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Duration of formation of magmatic system of polyphase Paleozoic alkaline complexes of the central Kola: U-Pb, Rb-Sr, Ar-Ar data     

A. A. Arzamastsev  L. V. Arzamastseva  A. V. Travin  B. V. Belyatsky  A. M. Shamatrina  A. V. Antonov  A. N. Larionov  N. V. Rodionov  S. A. Sergeev 《Doklady Earth Sciences》2007,413(3):432-436

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Duration of formation of magmatic system of polyphase Paleozoic alkaline complexes of the central Kola: U-Pb,Rb-Sr,Ar-Ar data     

A. A. Arzamastsev  L. V. Arzamastseva  A. V. Travin  B. V. Belyatsky  A. M. Shamatrina  A. V. Antonov  A. N. Larionov  N. V. Rodionov  S. A. Sergeev 《Doklady Earth Sciences》2007,413(2):432-436

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25 years of the Journal Tikhookeanskaya Geologiya     

A. I. Khanchuk  S. M. Rodionov  G. L. Kirillova 《Russian Journal of Pacific Geology》2007,1(1):1-2

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Optimal choice of the softening length and time step in <Emphasis Type="Italic">N</Emphasis>-body simulations     

S. A. Rodionov  N. Ya. Sotnikova 《Astronomy Reports》2005,49(6):470-476

A criterion for the choice of optimal softening length ε for the potential and the choice of time step dt for N-body simulations of a collisionless stellar system is analyzed. Plummer and Hernquist spheres are used as models to analyze how changes in various parameters of an initially equilibrium stable model depend on ε and dt. These dependences are used to derive a criterion for choosing ε and dt. The resulting criterion is compared to Merritt’s criterion for choosing the softening length, which is based on minimizing the mean irregular force acting on a particle with unit mass. Our criterion for choosing ε and dt indicate that ε must be a factor of 1.5–2 smaller than the mean distance between particles in the densest regions to be resolved. The time step must always be adjusted to the chosen ε (the particle must, on average, travel a distance smaller than 0.5 ε during one time step). An algorithm for solving N-body problems with adaptive variations of the softening length is discussed in connection with the task of choosing ε, but is found not to be promising.  相似文献   

Bending instability of stellar disks: The stabilizing effect of a compact bulge     

N. Ya. Sotnikova  S. A. Rodionov 《Astronomy Letters》2005,31(1):15-29

The saturation conditions for bending modes in inhomogeneous thin stellar disks that follow from an analysis of the dispersion relation are compared with those derived from N-body simulations. In the central regions of inhomogeneous disks, the reserve of disk strength against the growth of bending instability is smaller than that for a homogeneous layer. The spheroidal component (a dark halo, a bulge) is shown to have a stabilizing effect. The latter turns out to depend not only on the total mass of the spherical component, but also on the degree of mass concentration toward the center. We conclude that the presence of a compact (not necessarily massive) bulge in spiral galaxies may prove to be enough to suppress the bending perturbations that increase the disk thickness. This conclusion is corroborated by our N-body simulations in which we simulated the evolution of near-equilibrium, but unstable finite-thickness disks in the presence of spheroidal components. The final disk thickness at the same total mass of the spherical component (dark halo + bulge) was found to be much smaller than that in the simulations where a concentrated bulge is present.  相似文献   

Evidence for pole switching in the magnetic cataclysmic variable BY Camelopardalis     

Paul A. Mason  Gavin Ramsay  Ivan Andronov  Sergey Kolesnikov  Nickolay Shakhovskoy  & Elana Pavlenko 《Monthly notices of the Royal Astronomical Society》1998,295(3):511-518

An analysis of X-ray and optical light curves of the magnetic cataclysmic variable (MCV) BY Cam is presented. This system is one of three MCVs in which the spin period of the white dwarf and the binary orbital period differ by ∼1 per cent. As such these 'BY Cam' stars are important objects with which to probe the field structure of the magnetic white dwarf and ultimately the nature of synchronization of AM Her binaries. We confirm asynchronous rotation of the magnetic white dwarf with respect to the binary. We find evidence that the accretion stream accretes directly on to the white dwarf as in AM Her systems, but further, the stream impacts on to different magnetic poles over the course of the beat period. We present evidence that the optical and hard X-ray light curves modulate in phase, but together they are out of phase with the soft X-ray light curve. We confirm the spin down of the white dwarf which is expected to lead to the synchronization of the spin and orbital periods of BY Cam.  相似文献