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Search Results: 1 - 10 of 539417 matches for " V. A. Belov "
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The trajectory-coherent approximation and the system of moments for the Hartree type equation
V. V. Belov,A. Yu. Trifonov,A. V. Shapovalov
International Journal of Mathematics and Mathematical Sciences , 2002, DOI: 10.1155/s0161171202112142
Abstract: The general construction of semiclassically concentrated solutions to the Hartree type equation, based on the complex WKB-Maslov method, is presented. The formal solutions of the Cauchy problem for this equation, asymptotic in small parameter ℏ (ℏ→0), are constructed with a power accuracy of O(ℏ N/2), where N is any natural number. In constructing the semiclassically concentrated solutions, a set of Hamilton-Ehrenfest equations (equations for centered moments) is essentially used. The nonlinear superposition principle has been formulated for the class of semiclassically concentrated solutions of Hartree type equations. The results obtained are exemplified by a one-dimensional Hartree type equation with a Gaussian potential.
Semiclassical trajectory-coherent approximation in quantum mechanics: II. High order corrections to the Dirac operators in external electromagnetic field
V. G. Bagrov,V. V. Belov,A. Yu. Trifonov
Physics , 1998,
Abstract: High approximations of semiclassical trajectory-coherent states (TCS) and of semiclassical Green function (in the class of semiclassically concentrated states) for the Dirac operator with anomalous Pauli interaction are obtained. For Schrodinger and Dirac operators trajectory-coherent representations are constructed up to any precision with respect to h, h-->0.
A Simple Way to Estimate the Soft X-ray Class of Far-Side Solar Flares Observed with STEREO/EUVI
I. M. Chertok,A. V. Belov,V. V. Grechnev
Physics , 2015, DOI: 10.1007/s11207-015-0738-4
Abstract: Around the peaks of substantial flares, bright artifact nearly horizontal saturation streaks (B-streaks) corresponding to the brightest parts of the flare sources appear in the STEREO/EUVI 195 A images. We show that the length of such B-streaks can be used for the solution of an actual problem of evaluating the soft X-ray flux and class of far-side flares registered with double STEREO spacecraft but invisible from Earth. For this purpose from data on about 350 flares observed from January 2007 to July 2014 (mainly exceeding the GOES M1.0 level) both with GOES and STEREO, an empirical relation is established correlating the GOES 1-8 A peak flux and the B-streak length. This allowed us for the same years to estimate the soft X-ray classes for approximately 65 strong far-side flares observed by STEREO. The results of this simple and prompt method are consistent with the estimations of Nitta et al. (Solar Phys., 288, 241, 2013) based on the calculations of the EUVI full-disk digital number output. In addition, we studied some features of the B-streaks in impulsive and long-duration flares and demonstrated that B-streaks in several consecutive EUVI images can be used to reconstruct a probable time history of strong far-side flares.
The Ehrenfest system and the rest point spectrum for a Hartree-type Equation
V. V. Belov,M. F. Kondratieva,A. Yu. Trifonov
Mathematics , 2005,
Abstract: Following Ehrenfest's approach, the problem of quantum-classical correspondence can be treated in the class of trajectory-coherent functions that approximate as $\h\to 0$ a quantum-mechanical state. This idea leads to a family of systems of ordinary differential equations, called Ehrenfest M-systems (M=0,1,2,...), formally equivalent to the semiclassical approximation for the linear Schroedinger equation. In this paper a similar approach is undertaken for a nonlinear Hartree-type equation with a smooth integral kernel. It is demonstrated how quantum characteristics can be retrieved directly from the corresponding Ehrenfest systems, without solving the quantum equation: the semiclassical asymptotics for the spectrum are obtained from the rest point solution. One of the key steps is derivation of a modified nonlinear superposition principle valid in the class of trajectory-coherent quantum states.
Geometrical Description of the Local Integrals of Motion of Maxwell-Bloch Equation
A. V. Antonov,A. A. Belov,B. L. Feigin
Physics , 1995, DOI: 10.1142/S0217732395001332
Abstract: We represent a classical Maxwell-Bloch equation and related to it positive part of the AKNS hierarchy in geometrical terms. The Maxwell-Bloch evolution is given by an infinitesimal action of a nilpotent subalgebra $n_+$ of affine Lie algebra $\hat {sl}_2$ on a Maxwell-Bloch phase space treated as a homogeneous space of $n_+$. A space of local integrals of motion is described using cohomology methods. We show that hamiltonian flows associated to the Maxwell-Bloch local integrals of motion (i.e. positive AKNS flows) are identified with an infinitesimal action of an abelian subalgebra of the nilpotent subalgebra $n_+$ on a Maxwell- Bloch phase space. Possibilities of quantization and latticization of Maxwell-Bloch equation are discussed.
A. V. Antonov,A. A. Belov,K. Chaltikian
Physics , 1995, DOI: 10.1016/S0393-0440(96)00040-X
Abstract: We consider lattice analogues of some conformal theories, including WZW and Toda models. We describe discrete versions of Drinfeld-Sokolov reduction and Sugawara construction for the WZW model. We formulate perturbation theory in chiral sector. We describe the spaces of Integrals of Motion in the perturbed theories. We interpret the perturbed WZW model in terms of NLS hierarchy and obtain of this model into the lattice KP-hierarchy.
The burst of solar and geomagnetic activity in August–September 2005
A. Papaioannou, H. Mavromichalaki, E. Eroshenko, A. Belov,V. Oleneva
Annales Geophysicae (ANGEO) , 2009,
Abstract: During the August–September 2005 burst of solar activity, close to the current solar cycle minimum, a significant number of powerful X-ray flares were recorded, among which was the outstanding X17.0 flare of 7 September 2005. Within a relatively short period (from 22 August to 17 September) two severe magnetic storms were also recorded as well as several Forbush effects. These events are studied in this work, using hourly mean variations of cosmic ray density and anisotropy, derived from data of the neutron monitor network. During these Forbush effects the behavior of high energy cosmic ray characteristics (density and anisotropy) is analyzed together with interplanetary disturbances and their solar sources, and is compared to the variations observed in geomagnetic activity. A big and long lasting (~6 h) cosmic ray pre-decrease (~2%) is defined before the shock arrival on 15 September 2005. The calculated cosmic ray gradients for September 2005 are also discussed.
Solar cosmic rays during the extremely high ground level enhancement on 23 February 1956
A. Belov, E. Eroshenko, H. Mavromichalaki, C. Plainaki,V. Yanke
Annales Geophysicae (ANGEO) , 2005,
Abstract: The 23 February 1956 ground level enhancement of the solar cosmic ray intensity (GLE05) is the most famous among the proton events observed since 1942. But we do not have a great deal of information on this event due to the absence of solar wind and interplanetary magnetic field measurements at that time. Furthermore, there were no X-Ray or gamma observations and the information on the associated flare is limited. Cosmic ray data was obtained exclusively by ground level detectors of small size and in some cases of a non-standard design. In the present work all available data from neutron monitors operating in 1956 were analyzed, in order to develop a model of the solar cosmic ray behavior during the event. The time-dependent characteristics of the cosmic ray energy spectrum, cosmic ray anisotropy, and differential and integral fluxes have been evaluated utilizing different isotropic and anisotropic models. It is shown that the most outstanding features of this proton enhancement were a narrow and extremely intense beam of ultra-relativistic particles arriving at Earth just after the onset and the unusually high maximum solar particle energy. However, the contribution of this beam to the overall solar particle density and fluency was not significant because of its very short duration and small width. Our estimate of the integral flux for particles with energies over 100 MeV places this event above all subsequent. Perhaps the number of accelerated low energy particles was closer to a record value, but these particles passed mainly to the west of Earth. Many features of this GLE are apparently explained by the peculiarity of the particle interplanetary propagation from a remote (near the limb) source. The quality of the available neutron monitor data does not allow us to be certain of some details; these may be cleared up by the incorporation into the analysis of data from muonic telescopes and ionization chambers operating at that time. Keywords. Interplanatary physics (Cosmic rays; Energetic particles) – Solar physics, astrophysics and astronomy (Flares and mass injections) Full Article (PDF, 1072 KB) Citation: Belov, A., Eroshenko, E., Mavromichalaki, H., Plainaki, C., and Yanke, V.: Solar cosmic rays during the extremely high ground level enhancement on 23 February 1956, Ann. Geophys., 23, 2281-2291, doi:10.5194/angeo-23-2281-2005, 2005. Bibtex EndNote Reference Manager XML
Temperature effect of muon component and practical questions of how to take into account in real time
M. Berkova, A. Belov, E. Eroshenko,V. Yanke
Astrophysics and Space Sciences Transactions (ASTRA) , 2012, DOI: 10.5194/astra-8-41-2012
Abstract: A method has been developed to correct in real-time the cosmic ray (CR) muon component, observed by the muon telescopes of different geometry, for temperature effect.
Statistical analysis of solar proton events
V. Kurt, A. Belov, H. Mavromichalaki,M. Gerontidou
Annales Geophysicae (ANGEO) , 2004,
Abstract: A new catalogue of 253 solar proton events (SPEs) with energy >10MeV and peak intensity >10 protons/cm2.s.sr (pfu) at the Earth's orbit for three complete 11-year solar cycles (1970-2002) is given. A statistical analysis of this data set of SPEs and their associated flares that occurred during this time period is presented. It is outlined that 231 of these proton events are flare related and only 22 of them are not associated with Ha flares. It is also noteworthy that 42 of these events are registered as Ground Level Enhancements (GLEs) in neutron monitors. The longitudinal distribution of the associated flares shows that a great number of these events are connected with west flares. This analysis enables one to understand the long-term dependence of the SPEs and the related flare characteristics on the solar cycle which are useful for space weather prediction.
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