Diffusion approximation in overloaded switching queueing models

The asymptotic behavior of a queueing process in overloaded state-dependent queueing models (systems and networks) of a switching structure is investigated. A new approach to study fluid and diffusion approximation type theorems (without reflection) in transient and quasi-stationary regimes is suggested. The approach is based on functional limit theorems of averaging principle and diffusion approximation types for so-called Switching processes. Some classes of state-dependent Markov and non-Markov overloaded queueing systems and networks with different types of calls, batch arrival and service, unreliable servers, networks (MSM, Q/MSM, Q/1/∞ )r switched by a semi-Markov environment and state-dependent polling systems are considered

Characteristic of exit moments and models of enlargement of states for finite markov chains in terms of global memory functionals

A notion of local- and global-memory functions for discrete-type distributions is introduced by analogy with the notion of the memory for continuous-type distributions introduced in Muth's papers. In the class of PH-distributions (i.e., of distributions of the time of Markov chain exit from a subset of states) the necessary and sufficient conditions are obtained for the case where the exit time has an exponential (continuous-time) or a geometric (discrete time) distribution. A new notion of a global memory functional for decomposition of the state space of a finite Markov chain is introduced. Its properties as a measure of quality of decomposition and enlargement of a state space are studied. The asymptotic optimality is proved. © 2000 Kluwer Academic/Plenum Publishers

An approximate analytical method of analysis of a threshold maintenance policy for a multiphase multicomponent model

A multicomponent system is investigated that consists of n identical unreliable components whose nonfailure operating time consists of a number of sequential phases with exponential times. A maintenance policy is studied that proposes the instant replacement of all the components as soon as the number of components that are in some doubtful state (before a failure) amounts to a predefined threshold value. A cost function averaged over a large period is studied. For a fixed n, an analytical approach is considered. If n increases, a new approximate analytical approach is proposed, which is based on results of the type of the averaging principle for recurrent semi-Markovian processes. The conditions of existence and properties of the optimal strategy are studied. An example is considered and possibilities of generalizations are discussed. © 2003 Plenum Publishing Corporation

Z-theorems: Limits of stochastic equations

Let fn(0, a>) be a sequence of stochastic processes which converge weakly to a limit process fo(0, to). We show under some assumptions the weak inclusion of the solution sets On() = 0} in the limiting solution set OQ(CU) = {0: fo(0, u>) = 0}. If the limiting solutions are almost surely singletons, then weak convergence holds. Results of this type are called Z-theorems (zero-theorems). Moreover, we give various more specific convergence results, which have applications for stochastic equations, statistical estimation and stochastic optimization. © 2000 ISI/BS-

The asymptotic properties of estimates of the parameters of nonlinear time series

Asymptotic properties of nonlinear time series parameter estimators constructed on trajectories of stochastic systems under stationary and transient conditions are studied with the use of the least-squares method. The investigation method is based on the study of asymptotic properties of extremal sets of random functions. © 2000 Kluwer Academic/Plenum Publishers

Two-temperature relaxation and melting after absorption of femtosecond laser pulse

The theory and experiments concerned with the electron-ion thermal relaxation and melting of overheated crystal lattice constitute the subject of this paper. The physical model includes two-temperature equation of state, many-body interatomic potential, the electron-ion energy exchange, electron thermal conductivity, and optical properties of solid, liquid, and two phase solid-liquid mixture. Two-temperature hydrodynamics and molecular dynamics codes are used. An experimental setup with pump-probe technique is used to follow evolution of an irradiated target with a short time step 100 fs between the probe femtosecond laser pulses. Accuracy of measurements of reflection coefficient and phase of reflected probe light are ~1% and \sim 1\un{nm}, respectively. It is found that, {\it firstly}, the electron-electron collisions make a minor contribution to a light absorbtion in solid Al at moderate intensities; {\it secondly}, the phase shift of a reflected probe results from heating of ion subsystem and kinetics of melting of Al crystal during 0 where $t$ is time delay between the pump and probe pulses measured from the maximum of the pump; {\it thirdly} the optical response of Au to a pump shows a marked contrast to that of Al on account of excitation of \textit{d}-electronsComment: 6th International Conference on Photo-Excited Processes and Applications 9-12 Sep 2008, Sapporo, Japan, http://www.icpepa6.com, the contributed paper will be published in Applied Surface Science(2009

Features of Summer and Winter Precipitation in the Northern Part of the Black Sea Region: Two Model Case Studies

Purpose. The purpose of the study is to reproduce the evolution of clouds and precipitation and to evaluate the summer and winter precipitation features in the Black Sea region and Crimea using the WRF-ARW model. Methods and Results. The results of numerical simulations of the summer and winter atmospheric precipitation in Crimea, and the corresponding comparative characteristics are presented. Based on the example of the convection case in July 2018, shown are the convective activity diurnal dynamics and its spatial features induced by the breeze circulation over Crimea. Moisture balance analysis was performed, and quantitative estimates of the summer precipitation formation mechanism are given. The case study of December 2018 precipitation caused by the cyclone and associated cold front passage highlights the feature of the winter precipitation formation mechanism that is driven by moisture advection. The formation of intense winter and summer precipitation in the Crimean Mountains was also considered. Conclusions. The characteristic feature of summer precipitation is its diurnal periodicity and internal moisture cycle. The impact of breezes leads to the localization of convective clouds and precipitation in the central regions of the peninsula. The winter precipitation-forming cloudiness in Crimea consists predominantly of stratiform clouds; the precipitation patterns are conditioned by the large-scale circulation: the external moisture cycle is of a decisive character in winter. The high-altitude mountain areas are the zones of maximum precipitation in both seasons; they play an important role in the total moisture balance in Crimea

Langmuir waves excitation by electron beam with the limited cross-section in the near-Eearth electron foreshock

Model of the stripped monoenergetic electron beam with the sharp boundaries based on the results of CLUSTER measurements is proposed for the near-Earth foreshock vicinity. Dispersion equation is obtained and analyzed using numerical methods. Dependency of the equation roots corresponding to kinetic mechanism of beam-plasma instability on the model parameters is studied.Запропоновано модель моноенергетичного стрічкоподібного пучка з різкими границями, яка базується на результатах вимірювань експерименту КЛАСТЕР в області форшоку ударної хвилі Землі. Було отримано дисперсійне співвідношення, яке проаналізовано числовими методами. Вивчені залежності положення коренів, що відповідають кінетичному механізму плазмово-пучкової нестійкості, від параметрів моделі.Предложена модель моноэнергетического ленточного пучка с резкими границами, которая базируется на результатах измерений эксперимента КЛАСТЕР в области форшока ударной волны Земли. Было получено дисперсионное уравнение и проанализировано числовыми методами. Изучены зависимости положения корней дисперсионного уравнения, соответствующих кинетическому механизму плазменно-пучковой неустойчивости, от параметров модели

The assessment system of the grade of dysplastic changes in hip joint of children of early age

&nbsp;Aim: to analyze the method of choice of treatment for children aged 1-3 yrs. with hip joint dysplasia with respect to the complex of pathological changes by the elaboration of CAD programs. Material and Methods. We defined the grade of dysplastic changes in joint components of 82 children with hip joint dysplasia (113 joints) aged 1-3 yrs by CAD program. Results. The grade of dysplastic changes in hip joint (mild — I, moderate — II, severe — III) was identified with the elaborated program and the treatment was administered. We identified 28 children (33 joints) to have mild (I) dysplasia grade, moderate (II) 31 children (42 joints) and severe (III) 23 (38 joints). Mild dysplasia grade (I) corresponded to the score from 5 to 13, and to the option of conservative treatment with dynamic follow-up and coxarthritis prevention, moderate (II) — to the score from 14 to 26 and the option of intertrochanteric detorsion varus corrective osteotomy, severe (III) — to the score from 27 to 39 and the option of pelvis osteotomy and intertrochanteric detorsion varus corrective osteotomy. Conclusion. The treatment of patients with hip dysplasia depends on the grade of dysplastic changes. The elaborated program allows effectively define dysplasia grade and choose treatment method for the patients.</p

Mass spectra of doubly heavy Omega_QQ' baryons

We evaluate the masses of baryons composed of two heavy quarks and a strange quark with account for spin-dependent splittings in the framework of potential model with the KKO potential motivated by QCD with a three-loop beta-function for the effective charge consistent with both the perturbative limit at short distances and linear confinement term at long distances between the quarks. The factorization of dynamics is supposed and explored in the nonrelativistic Schroedinger equation for the motion in the system of two heavy quarks constituting the doubly heavy diquark and the strange quark interaction with the diquark. The limits of approach, its justification and uncertainties are discussed. Excited quasistable states are classified by the quantum numbers of heavy diquark composed by the heavy quarks of the same flavor.Comment: 14 pages, revtex4-file, 3 eps-figures, 5 tables, typos correcte