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Search Results: 1 - 10 of 88088 matches for " Aleksey I. Peschansky "
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Stationary Characteristics of the Single-Server Queue System with Losses and Immediate Service Quality Control  [PDF]
Aleksey I. Peschansky
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.24049
Abstract: Semi-Markovian model of operation of a single-server queue system with losses and immediate service quality control has been built. In case of unsatisfactory request service quality, its re-servicing is carried out. Re-servicing is executed till it is regarded satisfactory. Time between request income, and request service time are assumed to be random values with distribution functions of general kind. An explicit form of the system stationary characteristics has been defined.
Semi-Markovian Model of Monotonous System Maintenance with Regard to Operating Time to Failure of Each Element  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.28055
Abstract: An explicit form of reliability and economical stationary performance indexes for monotonous multicomponent system with regard to its elements’ maintenance has been found. The maintenance strategy investigated supposes preventive maintenance execution for elements that has attained certain operating time to failure. Herewith for the time period of elements’ maintenance or restoration operable elements are not deactivated. The problems of maintenance execution frequency optimization have been solved. For the model building the theory of semi-Markovian processes with a common phase field of states is used.
Semi-Markovian Model of Monotonous System Maintenance with Regard to its Elements’ Deactivation and Age  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.13029
Abstract: An explicit form of reliability and economical stationary performance indexes for monotonous multicomponent system with regard to its elements’ maintenance has been found. The maintenance strategy investigated supposes preventive maintenance execution for elements that has attained certain operating time to failure. Herewith for the time period of elements’ maintenance or restoration operable elements, functionally connected with the failed ones, are deactivated. The problems of maintenance execution frequency optimization have been solved. For the model building the theory of semi-Markovian processes with a common phase field of states is used.
Semi-Markovian Model of Control of Restorable System with Latent Failures  [PDF]
Yuriy E. Obzherin, Aleksey I. Peschansky, Yelena G. Boyko
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.23046
Abstract: Mathematical model of control of restorable system with latent failures has been built. Failures are assumed to be detected after control execution only. Stationary characteristics of system operation reliability and efficiency have been defined. The problem of control execution periodicity optimization has been solved. The model of control has been built by means of apparatus of semi-Markovian processes with a discrete-contin- uous field of states.
Semi-Markovian Model of Unreliable Control of Restorable System with Latent Failures  [PDF]
Yuriy E. Obzherin, Aleksei I. Peschansky, Yelena G. Boyko
Intelligent Information Management (IIM) , 2011, DOI: 10.4236/iim.2011.32006
Abstract: Semi-Markovian model of control of restorable system with latent failures has been built with regard to control errors. Stationary reliability and efficiency characteristics of its operation have been found. The problem of control execution periodicity optimization has been solved.
The Model for QCD Running Coupling Constant with Dynamically Generated Mass and Enhancement in the Infrared Region
Aleksey I. Alekseev
Physics , 1998,
Abstract: Nonperturbative studies of the strong running coupling constant in the infrared region are discussed. Starting from the analyses of the Dyson -- Schwinger equations in the gauge sector of QCD, the conclusion is made on an incomplete fixing of the perturbation theory summation ambiguity within "(forced) analytization procedure" (called also a dispersive approach). A minimal model for $\bar\alpha_s(q^2)$ is proposed so that the perturbative time-like discontinuity is preserved and nonperturbative terms not only remove the Landau singularity but also provide the ultraviolet convergence of the gluon condensate. Within this model, on the one hand, the gluon zero modes are enhanced (the dual superconductor property of the QCD vacuum) and, on the other hand, dynamical gluon mass generation is realized, with $m_g$ estimated as $0.6 GeV$. The uncertainty connected with the division into perturbative and nonperturbative contributions is discussed with the gluon condensate taken as an example.
Nonperturbative Contributions in an Analytic Running Coupling of QCD
Aleksey I. Alekseev
Physics , 2001, DOI: 10.1088/0954-3899/27/11/102
Abstract: In the framework of analytic approach to QCD the nonperturbative contributions in running coupling of strong interaction up to 4-loop order are obtained in an explicit form. For all $Q>\Lambda$ they are shown to be represented in the form of an expansion in inverse powers of Euclidean momentum squared. The expansion coefficients are calculated for different numbers of active quark flavors $n_f$ and for different number of loops taken into account. On basis of the stated expansion the effective method for precise calculation of the analytic running coupling can be developed.
On dependence of nonperturbative contributions in $\barα_s(q^2)$ on an initial approximation of perturbation theory in an analytic approach to QCD
Aleksey I. Alekseev
Physics , 2000,
Abstract: In the framework of analytic approach to QCD, which has been recently intensively developed, the dependence of nonperturbative contributions in a running coupling of strong interaction on initial perturbative approximation to 3-loop order is studied. The nonperturbative contributions are obtained in an explicit form. In the ultraviolet region they are shown to be represented in the form of the expansion in the inverse powers of Euclidean momentum squared. The expansion coefficients are calculated for different numbers of active quark flavors $n_f$ and for different numbers of loops taken into account. For all $n_f$ of interest it is shown that 2-loop order and 3-loop order corrections result in partial compensation of 1-loop order leading in the ultraviolet region nonperturbative contribution.
QCD Running Coupling: Freezing Versus Enhancement in the Infrared Region
Aleksey I. Alekseev
Physics , 1998,
Abstract: We discuss whether or not "freezing" of the QCD running coupling constant in the infrared region is consistent with the Schwinger -- Dyson (SD) equations. Since the consistency of the "freezing" was not found, the conclusion is made that the "analytization" method does not catch an essential part of nonperturbative contributions. Proceeding from the results on consistency of the infrared enhanced behaviour of the gluon propagator with SD equations, the running coupling constant is modified taking into account the minimality principle for the nonperturbative contributions in the ultraviolet region and convergence condition for the gluon condensate. It is shown that the requirements of asymptotic freedom, analyticity, confinement and the value of the gluon condensate are compatible in the framework of our approach. Possibilities to find an agreement of the enhanced behaviour of the running coupling constant with integral estimations in the infrared region are also discussed.
Nonperturbative Power Corrections in $\barα_s(q^2)$ of Two-Loop Analytization Procedure
Aleksey I. Alekseev
Physics , 1999,
Abstract: The analytization procedure which allows one to remove nonphysical singularities of the QCD running coupling constant $\bar\alpha_s(q^2)$ in the infrared region is applied to standard as well as to iterative solutions of the two-loop renormalization group equation. Non-leading at large momentum nonperturbative contributions in $\bar\alpha_s(q^2)$ are obtained in an explicit form. The coefficients of nonperturbative contributions expansions in inverse powers of the squared Euclidean momentum are calculated. For both cases considered there appear convergent at $q^2>\Lambda^2$ power series of negative terms with different dependence on term numbers.
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