Science department

UNARY FUNCTION OF HARD SPHERE DISTRIBUTION NEAR IDEAL WALL

Hard sphere system upon ideal wall was analyzed using equilibrium statistic physics methods. The integration equation for oneparticle distribution function of coordinate region is received. Resolve of
obtaining equation we analyzed. Numerical results illustrating particles local relative density depending of distance to the wall are showed.

 

CLUSTER SYNCHRONIZATION DESTRUCTION AND CHAOS IN AN INHOMOCENEOUS ACTIVE MEDIUM

We show that in an inhomogeneous self-sustained oscillatory medium the destruction of perfect clusters of partial synchronization, that is induced both by varying the control parameter and by noise, leads to the onset of chaotic behavior. We study the mechanisms of chaos formation in both cases. It is demonstrated that as parameters change, the transition to chaos in the deterministic medium can result from a hard (subcritical) period-doubling bifurcation and can be accompanied by intermittency.

RADIOTECHNICAL METHODS FOR THE ANALYSIS OF THE MULTIFREQUENCY WORKIING REGIMES OF THE BEAM DEVICES WITH LONGITUDINAL INTERACTION

The survey of the radiotechnical methods for the nonlinear amplifiers analysis is conducted. The presentation of the nonlinear amplifier as typical radiotechnical link, consisting of input and output filters and inertionless nonlinear amplifier, is proposed. The methods of the identification of the radiotechnical link elements are described. The problem of registration of amplitude-to-phase conversion is discussed. The possibility of the successful description of the multifrequency working regimes of the microwave amplifiers using the proposed model is demonstrated. 

 

РАДИОТЕХНИЧЕСКИЕ МЕТОДЫ АНАЛИЗА МНОГОЧАСТОТНЫХ РЕЖИМОВ РАБОТЫ ЛУЧЕВЫХ ПРИБОРОВ С ПРОДОЛЬНЫМ ВЗАИМОДЕЙСТВИЕМ

Проведен обзор радиотехнических методов анализа нелинейных усилителей. Предложено представление нелинейного усилителя в виде типового радиотехнического звена, состоящего из входного и выходного фильтров и безынерционного нелинейного элемента. Описаны методы идентификации элементов радиотехнического звена. Обсуждается проблема учета амплитудно-фазовой конверсии. Продемонстрирована возможность успешного описания с помощью предложенной модели многочастотных режимов работы СВЧ усилителей.

VIBRONIC SPECTRA AND STRUCTURE OF EXITED STATES OF POLYATOMIC MOLECULES

The methods of determination of molecular model parameters in exited electronic states are considered. Structural-dynamic models polyatomic molecules are developed using a semi-empirical method of hybridized atomic orbitals. It is shown that the electronic-vibrational spectra make it possible to identify the tautomeric forms in different phases states, taking into account the intermolecular interaction.

 

30LIT0NS AND CLUSTERS IN ONE-DIMENSIONAL ENSEMBLES OF INTERACTING BROWNIAN PARTICLES

The survey of the studies results of 1D ensembles dynamics of interacting Browniam particles is presented. Properties of both particles and the Fermi-Pasta-Ulam, Toda, Lennard-Jones, Morse interaction potentials are described. The Langevin equations are exhibited and structures and thermodynamic characteristics which may be extracted from data of a numerical integration of the equations are described. Excitations of phonons, cnoidal waves and solitons in dense ensembles and clusters in ensembles of low density are considered.

CONTEMPORARY PROBLEMS IN MODELING FROM TIME SERIES

Mathematical modeling from discrete sequences of experimental data (time series) is an actively developing field in mathematical statistics and nonlinear dynamics. It started from approximation of a set of data points on a plane with a smooth curve, while currently such empiric models take the form of sophisticated differential and difference equations and are capable of describing even nonlinear oscillatory and wave phenomena. Practical applications of the empiric models are various ranging from future forecasts to technical and medical diagnostics.

MODELLING THE DYNAMICS OF PHOTONIC CRYSTAL BROAD-AREA SURFACE EMITTING LASER

The lasers beam dynamics in photonic crystal laser is investigated numerically. The decomposition of transverse field distribution in terms of orthogonal modes of photonic crystal structure is used. The relation between the transverse structure of output beam and struc ture of pump region is demonstrated. The modification of the trans verse distribution of the pump allows to control of excitation of se lected transverse mode families. 

HETEROPHASE SEMICONDUCTORS UNDERACTION OF IRRADIATIONS

The history and current state of our heteropfiase photoconducting CdS-PbS films investigations are observed. Films were prepared by the vacuum evaporation method from the materials with limited mu tual solubility. Reasons of increased degradation stability with respect to radiation (in particular y- and electronic irradiations) are found out. Degradation stability is explained by diversion of recombination flow from wide-gap phase to narrow-gap. Radiation stimulated defects also move to narrow-gap phase.

CLASSICAL ANALYSIS OF RECOMBINATION OF ANTIHYDROGEN IN A STRONG MAGNETIC FIELD

Basing on numerical simulation of classical trajectories, the influence of a strong magnetic field on the rate of the spontaneous radiative recombination of antihydrogen atoms in cold antiproton-positron plasma is theoretically studied under the conditions of the ATHENA and ATRAP experiments carried out in CERN. The effect of the mag netic field is estimated by Monte-Carlo calculation of the change in the cross section of the positron hitting the near-nucleus region with the radius typical for the atomic ground state.

Pages