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71.
Positions of 17 filaments found inside the Perseid meteoroid stream by method of indices are compared with those of low-order mean-motion resonances with Jupiter and Saturn. By this comparing, the Jupiter and Saturn branches of the Perseid stream were identified. The existence of gaps in the distribution of the semi-major axes of the Perseids is confirmed using the more numerous material of a new version of the IAU Meteor Data Center Catalogue. Our integrations of the motion of particles in the Perseid stream lead to an extraordinary important fact. The found filaments are located in close proximity of strong resonances. They represent, with a high probability, increased numbers of particles gravitationally expelled from a resonant gap and (temporary) settled down in its close proximity. 相似文献
72.
Bilohuščin Vladimír Uher Pavel Koděra Peter Milovská Stanislava Mikuš Tomáš Bačík Peter 《Mineralogy and Petrology》2017,111(4):643-658
Mineralogy and Petrology - Borate minerals of the ludwigite group (LGM) and szaibélyite in association with hydroxylclinohumite, clinochlore, a serpentine mineral, magnesian magnetite, spinel,... 相似文献
73.
On 13 May 2000 parts of a penumbra were observed in an active region NOAA 8990 with the La Palma Stokes Polarimeter attached
to the Swedish Vacuum Solar Telescope. The stratification over the solar atmosphere of different physical parameters is retrieved
from these data by using the Stokes inversion based on response functions. The results confirm the previous findings of the
penumbral structure. In general, the magnetic field becomes weaker and more horizontal with increasing distance from the umbra
and the line-of-sight velocities are increasing towards the outer boundary of the penumbra. The results also suggest the existence
of the unresolved fine structure of the penumbra. The stratifications of the temperature and of the magnetic field strength
indicate the presence of rising flux tubes, which were predicted theoretically by Schlichenmaier, Jahn and Schmidt (1998,
Astron. Astrophys.
337, 897). 相似文献
74.
Images of post-flare coronal structures in X-rays 总被引:1,自引:0,他引:1
This is an extended abstract of several papers mentioned in the references describing extensive coronal structures related to radio continua and imaged in > 3.5 keV X-rays.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985. 相似文献
75.
76.
Zdeněk ?vestka 《Solar physics》2010,267(2):235-250
I recount my career in solar physics beginning at Ondřejov Observatory in 1948 and ending with my ∼30 year stay at the Laboratory
of Space Research in Utrecht. 相似文献
77.
78.
Velocity determination of 131 head echoes recorded during Perseid meteor shower observations by the Canadian 2 MW radar, has
been performed under the assumption of either their constant velocity or of its linear change with time. Even though the constant
velocities concentrated at 60 km s-1 generally accepted for the Perseids, a substantial number of echoes had velocities either
lower than 60 km s-1 or greater than this value. The inclusion of variable velocity into considerations led to surprising
result that a great portion of the head echoes accelerated (3 possibly decelerating echoes in comparison with 33 accelerating
cases on the level of relative standard deviations of output parameters not exceeding 10%). It seems that the allocation of
the ionization responsible for the head echo is not entirely identical with the instantaneous meteoroid position. As a consequence,
the velocity derived from the measured head echo coordinates can differ from the velocity of parent body. We are not able
to explain this finding at present.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
79.
Szilárd Szabó László Bertalan Ágnes Kerekes Tibor J. Novák 《International journal of geographical information science》2016,30(4):708-726
Decreasing population density is a current trend in the European Union, and causes a lower environmental impact on the landscape. However, besides the desirable effect on the regeneration processes of semi-natural forest ecosystems, the lack of traditional management techniques can also lead to detrimental ecological processes. In this study we investigated the land use pattern changes in a micro-region (in North-Eastern Hungary) between 1952 and 2005, based on vectorised land use data from archive aerial photos. We also evaluated the methodology of comparisons using GIS methods, fuzzy sets and landscape metrics. We found that both GIS methods and statistical analysis of landscape metrics resulted in more or less the same findings. Differences were not as relevant as was expected considering the general tendencies of the past 60 years in Hungary. The change in the annual rate of forest recovery was 0.12%; settlements extended their area by an annual rate of 3.04%, while grasslands and arable lands had a net loss in their area within the studied period (0.60% and 0.89%, respectively). The kappa index showed a smaller similarity (~60%) between these dates but the fuzzy kappa and the aggregation index, taking into account both spatial and thematic errors, gave a more reliable result (~70–80% similarity). Landscape metrics on patch and class level ensured the possibility of a detailed analysis. We arrived at a similar outcome but were able to verify all the calculations through statistical tests. With this approach we were able to reveal significant (p < 0.05) changes; however, effect sizes did not show large magnitudes. Comparing the methods of revealing landscape change, the approach of landscape metrics was the most effective approach, as it was independent of spatial errors and ensuring a multiple way of interpretation. 相似文献
80.
Zdeněk Kopal 《Astrophysics and Space Science》1968,1(3):284-300
The aim of the present paper will be to deduce the explicit form of differential equations which govern dynamical tides in close binary systems, with simplifications which are permissible for the mass-point model (Section 2), as well as for one exhibiting finite but high internal density concentration (Section 3). It is pointed out that, whereas the exact formulation of the problem leads to a simultaneous system of equations of sixth order (fourth in the inviscid case), this order reduces to four (or two for inviscid fluids) for the mass-point model; and to five (three for inviscid case) if the density concentration is high but finite.In the last section of this paper the coefficientsC
i,j which specify the amplitudes of the individual partial tides are explicitly formulated as functions of the time. 相似文献