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91.
Vladimir V. Kukarskih Nadezhda M. Devi Pavel A. Moiseev Andrey A. Grigoriev Maksim O. Bubnov 《山地科学学报》2018,15(4):722-729
This paper presents a dendroclimatic analysis of Siberian larch trees sampled along a latitudinal 260-km transect located in the Polar Urals,Russia. Three standardised chronologies were built over a length of 230–293 years using 79 individual tree-ring chronologies collected in the southern,middle and northern parts of the Polar Urals.Bootstrapped correlation functions showed that the annual growth of the larches was mainly influenced by the air temperatures in June and July. The relative role of the temperatures increased from south to north. Daily air temperature data analysis revealed that the duration of the growing season in the northern part of the Polar Urals is 24 days less than that in the southern part. At the present time, air temperatures exceeded threshold of 8~℃, 5 days earlier than it did in the beginning of the 20 th century In response to the increase in the duration of the growing season and the changing winter conditions in the Polar Urals over the last 130 years, radial growth–temperature relationships in larches have weakened;this effect was strongly pronounced in the southern part of the Polar Urals. 相似文献
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Vladimir N. Dvornychenko R. Bruce Gerding 《Celestial Mechanics and Dynamical Astronomy》1977,16(3):263-274
The gyroscopic motion of a spin-stabilized satellite due to gravity gradient torques in a circular orbit has been analyzed to varying degrees in numerous publications. This paper shows that the restriction to a circular orbit is, in fact, not essential and with a slight increase in complexity, noncircular orbits may be treated. More importantly, a uniform regression of the orbital node can also be accounted for. The general results are expressed in closed form using Jacobian elliptic functions. Finally, and this is perhaps most important, certain algebraic integrals of the precession are given which can be used to place limits on the excursions of the spin axis without actually solving for the motion. This allows one to design orientations such that the maximum angle between the orbit normal and spin axis never exceeds a specific amount even though the orbit normal is in precession. 相似文献
95.
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
96.
Agnieszka Gil Gennady A. Kovaltsov Vladimir V. Mikhailov Alexander Mishev Stepan Poluianov Ilya G. Usoskin 《Solar physics》2018,293(11):154
A usual event, called anisotropic cosmic-ray enhancement (ACRE), was observed as a small increase (\({\leq}\,5\%\)) in the count rates of polar neutron monitors during 12?–?19 UT on 07 June 2015. The enhancement was highly anisotropic, as detected only by neutron monitors with asymptotic directions in the southwest quadrant in geocentric solar ecliptic (GSE) coordinates. The estimated rigidity of the corresponding particles is \({\leq}\,1\) GV. No associated detectable increase was found in the space-borne data from the Geostationary Operational Environmental Satellite (GOES), the Energetic and Relativistic Nuclei and Electron (ERNE) on board the Solar and Heliospheric Observatory (SOHO), or the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instruments, whose sensitivity was not sufficient to detect the event. No solar energetic particles were present during that time interval. The heliospheric conditions were slightly disturbed, so that the interplanetary magnetic field strength gradually increased during the event, followed by an increase of the solar wind speed after the event. It is proposed that the event was related to a crossing of the boundary layer between two regions with different heliospheric parameters, with a strong gradient of low-rigidity (\({<}\,1\) GV) particles. It was apparently similar to another cosmic-ray enhancement (e.g., on 22 June 2015) that is thought to have been caused by the local anisotropy of Forbush decreases, with the difference that in our case, the interplanetary disturbance was not observed at Earth, but passed by southward for this event. 相似文献
97.
Rock displacement and thermal expansion study at historic heritage sites in Slovakia 总被引:1,自引:0,他引:1
Jan Vlcko Vladimir Greif Vladimir Grof Michal Jezny Lubomir Petro Martin Brcek 《Environmental Geology》2009,58(8):1727-1740
The paper discusses the results of the research devoted to the preservation of cultural heritage carried out within last two
decades in Slovakia. The aim of the study depended on monitoring of selected castle rocks showing instability problems due
to extremely slow displacements of creep character. Apart from traditional methods of investigation at one test site (Spis
Castle), authors implemented in their work the study of thermal expansion of the rocks as a result of seasonal periodic temperature
changes having potential influence on displacements and numerical modeling in order to understand better the landslide failure
mechanism. The results obtained from all study sites confirmed that even slow movements have to be implemented into preservation
and stabilization works in order to safeguard the sites of great historic value. 相似文献
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Mineralogy and Petrology - Contemporary mineralogy and geochemistry are concerned with understanding and deciphering processes that occur near the surface of the Earth. These processes are... 相似文献