Science for Education

From theory of oscillations to nonlinear dynamics

The paper deals with the retrospective consideration of course lectures on theory of oscillations in Nizhny Novgorod university and its evolution during more then 70 years.

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«Pre-defense» of thesis: formal requirements and traditions

Opinions of secretaries of dissertation councils on Physics and Mathematics about holding scientific seminar presenting dissertation to defense are given.

Outline of thesis general characteristics: rules, recommendations, samples

The presentment structure of general characteristics of dissertation and its abstract are discussed.

On the mechanism of «compressed»state formation at relativistic electron beam in twosection drift tube

This paper is devoted to the threedimensional numerical simulation of the «compressed» state of the relativistic electron beam in twosection vircator system with drift tubes with different diameters. We have discovered the mechanism of formation of the «compressed» state of the relativistic beam through the formation of two virtual cathode near the anode grid and between connected sections, which will eventually merged into one distributed in the drift space virtual cathode (compressed state of the beam).

Research of ultrawide range sband chaos generator based on TWT

The paper presents the results of the experimental research ultrawide range sband chaos generator based on TWT. The effect of absolute suppression mode chaotic signal by external harmonic signal has been investigated.

Numerical calculation of the electrodynamic characteristics of the diode oscillator with photonic crystal resonator

Design of a diode oscillator with a fieldemission cathode placed in a photonic crystal (PC) resonator is described. Results of numerical calculation of basic electrodynamic parameters of the PC resonator are presented. The 3D electrodynamic simulation by using the modern software package HFSS shows that varying the design of the energy output allows control of the loaded Qfactor in a wide range. Selection of the optimal value of the loaded Qfactor provides rather high output power and efficiency for reasonable values of the fieldemission cathode current density.

Features of formation of band gaps in coupled structures based on magnonic crystals

There are introduced ferromagnetic periodic structures consist of two coupled magnonic crystals and related magnonic and crystal film, separated by a dielectric layer. The dispersion equation made for magnetostatic waves, that propagate in such structures and identified main features of formation band gaps and a comparison with a periodic structure of one magnonic crystal was made.

Dynamics of two fieldcoupled spintransfer oscillators

The model of two fieldcoupled spintransfer oscillators has been derived and studied. It has been shown that this model demonstrates phase synchronization in a wide bandwidth, quasiperiodic oscillations and chaos.

Technique and results of numerical test for hyperbolic nature of attractors for reduced models of distributed systems

A test of hyperbolic nature of chaotic attractors, based on an analysis of statistics distribution of angles between stable and unstable subspaces, is applied to reduced finitedimensional models of distributed systems which are the modifications of the Swift–Hohenberg equation and Brusselator model, as well as to the problem of parametric excitation of standing waves by the modulated pump.

The study of multistability and external synchronization in nonautonomous system of two coupled van der pol oscillators with repulsive coupling

In this paper we study the bifurcational mechanisms of synchronization and multistability formation in a system of two interacting van der Pol oscillators, one of which is under external harmonic forcing. We draw a twoparametric bifurcation diagram for phasereduced system and study its evolution in transition from symmetrical to asymmetrical repulsive interaction. Relying on the results of bifurcation analysis of nonreduced system we conclude that the synchronization scenarios found in the phasereduced system correspond to the ones in the nonreduced system.

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