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Search Results: 1 - 10 of 9422 matches for " Vladimir Popov "
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From super-charged nuclei to massive nuclear density cores
Vladimir Popov
Physics , 2010, DOI: 10.1063/1.3382318
Abstract: Due to $e^+e^-$-pair production in the field of supercritical $(Z \gg Z_{cr}\approx 170 $) nucleus an electron shell, created out of the vacuum, is formed. The distribution of the vacuum charge in this shell has been determined for super-charged nuclei $Ze^3 \ga 1$ within the framework of the Thomas-Fermi equation generalized to the relativistic case. For $Ze^3 \gg 1$ the electron shell penetrates inside the nucleus and almost completely screens its charge. Inside such nucleus the potential takes a constant value equal to $V_0=-(3\pi^2 n_p)^{1/3} \sim -2m_{\pi}c^2$, and super-charged nucleus represents an electrically neutral plasma consisting of $e,p$ and $n$. Near the edge of the nucleus a transition layer exists with a width $\lambda \approx \alpha^{-1/2} \hbar/m_{\pi} c\sim 15$ fm, which is independent of $Z (\hbar/m_{\pi} c \ll \lambda \ll \hbar/m_e c)$. The electric field and surface charge are concentrated in this layer. These results, obtained earlier for hypothetical superheavy nuclei with $Z \sim A/2\la 10^4 \div 10^6$, are extrapolated to massive nuclear density cores having a mass number $A \approx (m_{Planck}/m_n)\sim 10^{57}$. The problem of the gravitational and electrodynamical stability of such objects is considered. It is shown that for $A \ga 0.04 (Z/A)^{1/2}(m_{Planck}/m_n)^3$ the Coulomb repulsion of protons, screened by relativistic electrons, can be balanced by gravitational forces. The overcritical electric fields $E\sim m^2_{\pi} c^3/e\hbar$ are present in the narrow transition layer near the core surface.
Relativistic Kinetics of Phonon Gas in Superfluids
Vladimir Popov
Physics , 2006, DOI: 10.1007/s10714-006-0272-7
Abstract: The relativistic kinetic theory of the phonon gas in superfluids is developed. The technique of the derivation of macroscopic balance equations from microscopic equations of motion for individual particles is applied to an ensemble of quasi-particles. The necessary expressions are constructed in terms of a Hamilton function of a (quasi-)particle. A phonon contribution into superfluid dynamic parameters is obtained from energy-momentum balance equations for the phonon gas together with the conservation law for superfluids as a whole. Relations between dynamic flows being in agreement with results of relativistic hydrodynamic consideration are found. Based on the kinetic approach a problem of relativistic variation of the speed of sound under phonon influence at low temperature is solved.
A Model for a Spherically Symmetric Space Generated by a Spherical Gravitational Source and a Gravitational Medium with Constant Mass Density  [PDF]
Nikolaj N. Popov, Vladimir I. Tsurkov
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32A004

A metric on a spherically symmetric space generated by a spherical source of gravity and filled with a gravitational medium is constructed, and criteria for the continuity of this metric on the entire space (which is equivalent to the absence of black holes) are found. Properties of radial geodesics under various constraints on the size of the gravitational source, its mass, and the mass density of the gravitational medium are studied.

The Hamiltonian Alternating Path Problem
Anna Gorbenko,Vladimir Popov
IAENG International Journal of Applied Mathematics , 2012,
Sorting by Prefix Reversals
Vladimir Yu. Popov
IAENG International Journal of Applied Mathematics , 2010,
The c-Fragment Longest Arc-Preserving Common Subsequence Problem
Anna Gorbenko,Vladimir Popov
IAENG International Journal of Computer Science , 2012,
The Approximate Period Problem
Vladimir Yu. Popov
IAENG International Journal of Computer Science , 2009,
Strategies for Development of a Distributed Framework for Computational Sciences
Vladimir Berezovsky,Alexander Popov
Physics , 2011,
Abstract: This paper discusses some generic approach for developing grid-based framework for enabling establishment of workflows comprising existing software in computational sciences areas. We highlight the main requirements addressed the developing of such framework. Some strategies for enabling interoperability between convenient computation software in the grid environment has been shown. The UML based instruments of graphical description of workflows for the developing system has been suggested.
Nonsingular Chaplygin gas cosmologies in universes connected by wormhole
Anna Mokeeva,Vladimir Popov
Physics , 2012, DOI: 10.1134/S0202289313010076
Abstract: We present some exact solutions of the Einstein equations with an anisotropic fluid exploiting the Chaplygin equation of state. The solutions describe spacetimes with two identical T regions and an intermediate static spherically symmetric R region containing a wormhole. The metric in the T region represents an anisotropic Kantowski-Sachs cosmological model. Its evolution starts from an event horizon and develops according to different scenarios including eternal expansion, contraction and also a finite universe lifetime.
Isotropization in Chaplygin matter universes connected by a wormhole
Anna Mokeeva,Vladimir Popov
Physics , 2013, DOI: 10.1142/S0218271813500673
Abstract: Chaplygin anisotropic matter governing the cosmological evolution in two identical universes with an intermediate static spherically symmetric region is considered. The static region contains a wormhole allowing one to pass etween two horizons. The metric in the non-static region represents a kind of an anisotropic Kantowski-Sachs cosmological model starting from a horizon instead the initial singularity. A classification of the cosmologies with a monotonic late stage is presented. It is shown that only one scenario can involve a de Sitter regime. The scales in the de Sitter phase allows one to describe the earliest accelerated expansion on the classical level.
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