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Search Results: 1 - 10 of 3977 matches for " Sergey Kondratyev "
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Nutrient Loading on the Eastern Gulf of Finland (Baltic Sea) from the Russian Catchment Area
Sergey Kondratyev, Nathaniel Trumbull
Journal of Hydrology and Hydromechanics , 2012, DOI: 10.2478/v10098-012-0012-5
Abstract: The identification and examination of sources of external loading are important pressure indicators for studying the nutrient balance and eutrophication of water bodies. Focusing on the eastern Gulf of Finland, this paper investigates and decomposes the sources of phosphorus, a limiting factor of eutrophication of the Gulf and its accompanying Neva Bay, and of nitrogen as pressure indicators. The eastern Gulf of Finland's catchment basin represents Europe's largest freshwater basin. Both point and non-point sources of pollution, as well as their current and possible withdrawals from the watershed's nutrient loading, are considered. The investigation identifies poultry plants and animal husbandry enterprises in the coastal watershed as critical contributing sources to eutrophication in the eastern Gulf of Finland. Analyses based on such pressure indicators can help to contribute directly to future policy-making as concerns environmental protection measures and water resources planning in the eastern Gulf of Finland and other regions.
Creation and transmutation of magnetized nuclei at explosively dense matter
Kondratyev V. N.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123817008
Abstract: Synthesis of iron group chemical elements is considered for the ultra-magnetized astrophysical plasma in supernovae. Maximum of nucleosynthesis products is shown to shift towards smaller mass numbers approaching titanium due to magnetic modification of nuclear structure. The results are corroborated with an excess of 44Ti revealed from the INTEGRAL mission data.
Entropy and Irreversibility in Classical and Quantum Mechanics  [PDF]
V.A. Antonov, B.P. Kondratyev
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.26061
Abstract: Review of the irreversibility problem in modern physics with new researches is given. Some characteristics of the Markov chains are specified and the important property of monotonicity of a probability is formulated. Using one thin inequality, the behavior of relative entropy in the classical case is considered. Further we pass to studying of the irreversibility phenomena in quantum problems. By new method is received the Lindblad’s equation and its physical essence is explained. Deep analogy between the classical Markov processes and development described by the Lindblad’s equation is conducted. Using method of comparison of the Lind-blad’s equation with the linear Langevin equation we receive a system of differential equations, which are more general, than the Caldeira-Leggett equation. Here we consider quantum systems without inverse influ-ence on a surrounding background with high temperature. Quantum diffusion of a single particle is consid-ered and possible ways of the permission of the Schrödinger’s cat paradox and the role of an external world for the phenomena with quantum irreversibility are discussed. In spite of previous opinion we conclude that in the equilibrium environment is not necessary to postulate the processes with collapses of wave functions. Besides, we draw attention to the fact that the Heisenberg’s uncertainty relation does not always mean the restriction is usually the product of the average values of commuting variables. At last, some prospects in the problem of quantum irreversibility are discussed.
Kinetic Equationins in the Theory of Normal Fermi Liquid
I. Siddique,A. S. Kondratyev
Physics , 2007,
Abstract: On the bases of the improved approximation for the spectral function of one-particle states the Landau-Silin kinetic equations for the normal Fermi liquids of neutral and electrically charged particles are shown to be valid at finite temperature above the temperature of superfluid transition.
Spectral Function and Kinetic Equation for Normal Fermi Liquid
M. Arshad,A. S. Kondratyev,Imran Siddique
Physics , 2007, DOI: 10.1103/PhysRevB.76.054306
Abstract: On the basis of the Kadanoff-Baym (KB) varient of the time dependent Green's function method a new ansatz for the approximation of a spectral function is offered. The ansatz possesses all the advantages of quasiparticle (QP) and extended quasiparticle (EQP) approximations and satisfies the KB equation for a spectral function in the case of slightly nonequilibrium system when disturbances in space and time are taken into consideration in the gradient approximation. This feature opens new opportunities for the microscopic derivation of the Landau kinetic equation for the quasiparticle distribution function of the normal fermi liquid and provides the widening of these equation's temperature rang of validity.
On the bulk velocity of Brownian ratchets
Stanislav Kondratyev,José Miguel Urbano,Dmitry Vorotnikov
Mathematics , 2014,
Abstract: In this paper we study the unidirectional transport effect for Brownian ratchets modeled by Fokker-Planck-type equations. In particular, we consider the adiabatic and semiadiabatic limits for tilting ratchets, generic ratchets with small diffusion, and the multi-state chemical ratchets. Having established a linear relation between the bulk transport velocity and the bi-periodic solution, and using relative entropy estimates and new functional inequalities, we obtain explicit asymptotic formulas for the transport velocity and qualitative results concerning the direction of transport. In particular, we prove the conjecture by Blanchet, Dolbeault and Kowalczyk that the bulk velocity of the stochastic Stokes' drift is non-zero for every non-constant potential.
A new optimal transport distance on the space of finite Radon measures
Stanislav Kondratyev,Léonard Monsaingeon,Dmitry Vorotnikov
Mathematics , 2015,
Abstract: We introduce a new optimal transport distance between nonnegative finite Radon measures with possibly different masses. The construction is based on non-conservative continuity equations and a corresponding modified Benamou-Brenier formula. We establish various topological and geometrical properties of the resulting metric space, derive some formal Riemannian structure, and develop differential calculus following F. Otto's approach. Finally, we apply these ideas to identify an ideal free distribution model of population dynamics as a gradient flow and obtain new long-time convergence results.
An Efficient Numerical Method for Calculation of Elastic and Thermo-Elastic Fields in a Homogeneous Medium with Several Heterogeneous Inclusions  [PDF]
Sergey Kanaun
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.12005
Abstract: The work is devoted to calculation of static elastic and thermo-elastic fields in a homogeneous medium with a finite number of isolated heterogeneous inclusions. Firstly, the problem is reduced to the solution of inte-gral equations for strain and stress fields in the medium with inclusions. Then, Gaussian approximating func-tions are used for discretization of these equations. For such functions, the elements of the matrix of the dis-cretized problem are calculated in explicit analytical forms. The method is mesh free, and only the coordi-nates of the approximating nodes are the geometrical information required in the method. If such nodes compose a regular grid, the matrix of the discretized problem obtains the Toeplitz properties. By the calcula-tion of matrix-vector products with such matrices, the Fast Fourier Transform technique may be used. The latter accelerates essentially the process of the iterative solution of the disretized problem. The results of calculations of elastic fields in 3D-medium with an isolated spherical heterogeneous inclusion are compared with exact solutions. Examples of the calculation of elastic and thermo-elastic fields in the medium with several inclusions are presented.
The use of DCEEG to estimate functional and metabolic state of nervous tissue of the brain at hyper- and hypoventilation  [PDF]
Sergey Murik
World Journal of Neuroscience (WJNS) , 2012, DOI: 10.4236/wjns.2012.23027
Abstract: A pilot study has been made of the simultaneous DC potential and total slow electrical activity changes during modeling various metabolic and functional states of the human brain. The multi-electrode DCEEG recordings have been performed during the hyperventilation (frequent deep one-minute long breathing motions) and the hypoventilation (voluntary breath holding). It has been shown that the ischemic state occurring in hyperventilation is accompanied by the negative shift of DC potential and increase in the EEG rhythms amplitude. A distention of brain vessels during hypoventilation (voluntary breath-hold) and an improvement of blood supply and thus improvement of vital and functional state of neurons gave rise to an increase in the EEG rhythm amplitude too, though against a background of a positive DC-potential shift. Obtained results are considered with context the generation of the qualitatively different functional states of brain cells during hyper- and hypoventilation which is reflected in their resting potential and activity. The conducted study show the prospects for DCEEG and the method we used for DCEEG data processing to understand the character of functional and metabolic changes in the nervous tissue.
User-Driven Applications—New Paradigm for Interface Design  [PDF]
Sergey Andreyev
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.68047
Abstract:

40 years ago the outcome of computer programs was in the form of long listings covered by numbers; even the format of those numbers was determined by developers. Throughout the latest 30 years program views and results are shown in a wide variety of shapes and variants, but all these possibilities are predefined and fixed in code by developers; nothing outside of their approved solutions is allowed. My vision from now on into the future: developers are responsible only for correct work of a program (calculations, link with the database, etc.) and suggest a good default interface but not determine all possible scenarios; only users decide WHAT, WHEN, and HOW to show. This will be a revolution in our interaction with computers, but there are obvious questions. How this step can be made? Do all users need such change? Is it going to be a burden for users or a welcome revolution?

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