ISSN 0869-6632 (Print)
ISSN 2542-1905 (Online)

Applied Problems of Nonlinear Oscillation and Wave Theory

Experimental research of self-oscillation destruction under additive noise action

Evolution of probabilistic distribution in self-sustained oscillators with increase of noise intensity is studied by means of numerical simulation and natural experiments. Two different systems are considered: van der Pol and Anishchenko–Astakhov self-sustained oscillators. Destruction of probabilistic distribution form, which is typical for noisy selfoscillation, by additive noise is showed.

Coherence resonance in uhf devices with long interaction

This work presents results of experimental studies of coherence resonance phenomenon in UHF devices with long interaction (TWT and BWO). Basic properties of this phenomenon were investigated. Discovered suppression effect of resonant response on external noise by external harmonic signal. This suppression effect can be used to increase signal-tonoise ratio in system’s output. Specific features of coherence resonance phenomenon in long-interaction devices also noted.

Dynamics of two nonlinearly coupled nonidentical Lang–Kobayshi oscillators

One-parameter study of system of two nonlinearly coupled nonidentical Lang– Kobayshi oscillators is presented. The time delay influence on oscillation regimes in the system is studied. The posibility of periodic and quasiperiodic oscillations is shown. Variation of delay time leads to bifurcations and an alternation of periodic and quasiperiodic oscillations. Quasiperiodic oscillations are excited as a result of Neimark–Sacker bifurcation.

The study of the unidirectionally coupled generators of robust chaos and wide band communication scheme based on its synchronization

A numerical simulation of a wide band or secure communication scheme, based on nonlinear admixture of an information signal to the chaotic one, and on synchronization of the transmitter and receiver generators, manifesting hyperbolic chaos. Synchronization of the transmitter and receiver is provided by a strong unidirectional coupling between them. The study of the possibility of synchronization between subsystems and functionality of the communication scheme are presented.

Subharmonic resonance in a system of two dissipative coupled van der Pol oscillators with external force

The problem of the excitation of two coupled oscillators is discussed in the case of the simple subharmonic resonance between the external force and eigen-frequencies of the oscillators. The corresponded phase equation is obtained. We showed that the form of the synchronization tongue and transformation of the region of the two-, three-frequency tori by varying the parameter of the coupling between the oscillators is significantly different from the case of the main resonance.

Destruction of the coherent mode in system of two oscillators at the strong resonant mutual couplings

The hypothesis about destruction of a coherent mode in system of two mutual couplings microwave oscillators is examine, each of which in a stand-alone mode generates stable unifrequent oscillations. It is experimentally shown, that at strong resonant couplings synchronous oscillations are unstable, therefore the system go over in in a mode of dynamic chaos. 

The studies of the arising of oscillations in the quasi­harmonic model of the self­sustained oscillatory medium under multiplicative noise excitation

The multiplicative noise influence on the self-sustained oscillatory medium near the oscillation threshold is studied. The chain of the identical quasi-harmonic self-sustained oscillators with the periodic boundary conditions is taken as a simplest model of the oscillatory medium. The parameters of the oscillators are modulated with the white Gaussian noise. The stochastic bifurcations are analyzed for the cases of homogenous and spatially-nonhomogenous noise. 

Nonlinear effects in autooscillatory system with frequency-phase control

Dynamical modes and nonlinear phenomena in the models of oscillatory system with frequency-phase control in the case of periodic nonlinear characteristics of frequency discriminator are investigated. Stability of synchronous mode is analyzed. The existences of a great number various periodic and chaotic nonsynchronous modes are established. Peculiarities of the system dynamics caused by parameters of frequency control loop are considered.

Effect of low-frequency vibrations on nonlinear dissipative forces

The paper examines the impact of the slow movements to effective values of dissipative forces in the equations of fast motion of oscillatory system. It was previously shown that the dissipative characteristics obtained experimentally under harmonic oscillations can change significantly with polyharmonic excitation. In this paper the problem is considered in more detail in relation to the determination of the resonance amplitudes and threshold conditions for parametric and subharmonic resonances.

The investigation of subterahertz gyrotron for dnp spectroscopy in the IAP RAS

The paper presents the results of research is carried out in the Institute of Applied Physics and is aimed at creating a CW submillimeter gyrotrons with an output power of several tens of watts. Results of experiments on the 258 GHz gyrotron at the second harmonic of the gyrofrequency are presented. In the course of experiments maximum output power of 200 W and the relative stability of the output frequency at 5 · 10−6 for the hours-long continuous operation of the gyrotron were achieved.

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