排序方式: 共有40条查询结果,搜索用时 234 毫秒
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Dragan Slavkov Hajdukovic 《Astrophysics and Space Science》2014,349(1):1-4
In the absence of the physical understanding of the phenomenon, different empirical laws have been used as approximation for distribution of dark matter in galaxies and clusters of galaxies. We suggest a new profile which is not empirical in nature, but motivated with the physical idea that what we call dark matter is essentially the gravitational polarization of the quantum vacuum (containing virtual gravitational dipoles) by the immersed baryonic matter. It is very important to include this new profile in forthcoming studies of dark matter halos and to reveal how well it performs in comparison with empirical profiles. A good agreement of the profile with observational findings would be the first sign of unexpected gravitational properties of the quantum vacuum. 相似文献
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Igor Leščešen Urošev Marko Dolinaj Dragan Pantelić Milana Telbisz Tamás Varga György Savić Stevan Milošević Dragan 《Water Resources》2019,46(6):853-860
Water Resources - Floods are one of the most common natural hazards and as such, they are causing a great loss of human life as well as great economic damages. Flood frequency analysis (FFA) is... 相似文献
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Todorović Bratislav Ž. Stojiljković Dragan T. Pantić Tanja Petrović Matović Branko Djordjević Marija Prekajski Petrović Sanja M. Stojiljković Milena S. Stevanović Miloš M. 《Natural Resources Research》2019,28(4):1259-1267
Natural Resources Research - There are no available data about direct burkeite formation on the geothermal waters pipelines in Europe. Data about accompanying minerals of burkeite are also scarce.... 相似文献
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Bojan Vršnak Darije Maričić Andrew L. Stanger Astrid M. Veronig Manuela Temmer Dragan Roša 《Solar physics》2007,241(1):85-98
We study kinematics of 22 coronal mass ejections (CMEs) whose motion was traced from the gradual pre-acceleration phase up
to the post-acceleration stage. The peak accelerations in the studied sample range from 40, up to 7000 m s−2, and are inversely proportional to the acceleration phase duration and the height range involved. Accelerations and velocities
are, on average, larger in CMEs launched from a compact source region. The acceleration phase duration is proportional to
the source region dimensions; i.e., compact CMEs are accelerated more impulsively. Such behavior is interpreted as a consequence of stronger Lorentz force and
shorter Alfvén time scales involved in compact CMEs (with stronger magnetic field and larger Alfvén speed being involved at
lower heights). CMEs with larger accelerations and velocities are on average wider, whereas the widths are not related to
the source region dimensions. Such behavior is explained in terms of the field pile-up ahead of the erupting structure, which
is more effective in the case of a strongly accelerated structure. 相似文献
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Alkali basalts were discovered in the Timok Magmatic Complex only in a borehole near Zlot. They are composed of plagioclase and clinopyroxene phenocrysts lying in intersertal to pilotaxitic groundmass. The characteristic feature of these rocks is the high content of needle shaped magnetite.
Various disequilibrium features in alkali basalt of Zlot reflect complex convection effects and recharge, most probably in a shallow magma chamber. Major and trace elements data indicate that alkali basalts of Zlot originated from magmas deriving from metasomatized mantle wedge above a subducting and dehydrating plate. However the investigated rocks did not originate from primary magmas, but from a magma which has undergone considerable fractional crystallization. 相似文献
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Dragan Slavkov Hajdukovic 《Astrophysics and Space Science》2012,339(1):1-5
The cosmological constant problem is the principal obstacle in the attempt to interpret dark energy as the quantum vacuum
energy. We suggest that the obstacle can be removed, i.e. that the cosmological constant problem can be resolved by assuming
that the virtual particles and antiparticles in the quantum vacuum have the gravitational charge of the opposite sign. The
corresponding estimates of the cosmological constant, dark energy density and the equation of state for dark energy are in
the intriguing agreement with the observed values in the present day Universe. However, our approach and the Standard Cosmology
lead to very different predictions for the future of the Universe; the exponential growth of the scale factor, predicted by
the Standard Cosmology, is suppressed in our model. 相似文献
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Dragan Slavkov Hajdukovic 《Astrophysics and Space Science》2011,334(2):219-223
We wonder if a cyclic universe may be dominated alternatively by matter and antimatter. Such a scenario demands a mechanism
for transformation of matter to antimatter (or antimatter to matter) during the final stage of a big crunch. By giving an
example, we have shown that in principle such a mechanism is possible. Our mechanism is based on a hypothetical repulsion
between matter and antimatter, existing at least deep inside the horizon of a black hole. When universe is reduced to a supermassive
black hole of a small size, a very strong field of the conjectured force might create (through a Schwinger type mechanism)
particle-antiparticle pairs from the quantum vacuum. The amount of antimatter created from the vacuum is equal to the decrease
of mass of the black hole and violently repelled from it. When the size of the black hole is sufficiently small, the creation
of antimatter may become so fast, that matter of our Universe might be transformed to antimatter in a fraction of second.
Such a fast conversion of matter into antimatter may look as a Big Bang. Our mechanism prevents a singularity; a new cycle
might start with an initial size more than 30 orders of magnitude greater than the Planck length, suggesting that there is
no need for inflationary scenario in Cosmology. In addition, there is no need to invoke CP violation for explanation of matter-antimatter
asymmetry. Simply, our present day Universe is dominated by matter, because the previous universe was dominated by antimatter. 相似文献