Bifurcations in Dynamical Systems

We consider the chain of three dissipatively coupled self-oscillating systems with non-identical controlling parameters. We observe situations, when coupling damps different oscillators. The structure of the frequency mismatch – coupling value parameter plane is investigated with a view to the location of oscillator death area, complete synchronization area, two- and three-frequency quasiperiodic regimes. Features, connected with non-identity in controlling parameters, are considered.

Pulsed driven system of two coupled van der Pol oscillators in the regime of synchronization 1:1 and «oscillator death» is researched. The existence of islands of quasi-periodic regimes on the parameter plane period – amplitude of perturbation in the radiophysics experiment are shown. The different types of oscillations in this system are illustrated.

The transition to chaos through the destruction of three-dimensional torus is studied in a nonautonomous system with quasi-periodic impact as example. Analysis is carried out of the influence both of additive noise and frequency fluctuations impact on the stability of three-dimensional torus. It is shown that under the influence of additive noise and frequency fluctuations impact Lyapunov exponent remains negative. This allows to conclude that in this model three-dimensional torus is structurally stable in contrast to theautonomous system.

In this paper we study the optimum form of external influence with low power necessary for activation of one-dimensional dynamical system. The Lagrange multipliers method is used. Optimum influence with low power and optimum law of change of a dynamical system state are determined analytically for linear dynamical system and numerically for nonlinear dynamical system. The opportunity of influence power reduction vs its duration is investigated. The efficiency of optimum influence expressed in economy of energy quantity, spent on it, in comparison to rectangular influence is studied.

A new approach is considered to design of parametric generators of chaos with hyperbolic attractors on the basis of two alternately excited subsystems, each consisting of three oscillators, one of which plays the role of the pump source. In contrast to previously proposed schemes, the angular variable undergoing a multiple increase over each characteristic period is a quantity characterizing the amplitude ratio of two oscillators, rather then the phase of successive oscillation trains.

A scheme of circular nonautonomous system is introduced, which is supposed to generate hyperbolic chaos. Its operation is based on doubling of phase on complete cycle of the signal transmission. This is a criterion for the Smale–Williams attractor to exist. The performance is realized due to smooth periodic variation of natural frequency in one of the two oscillatory subsystems, which compose the ring, from reference value to the doubled one.

In this paper we investigate modified «Arnold cat» map with dissipative terms, in which a hyperbolic chaos exists for small perturbation magnitudes, and in a certain range a hyperbolic chaotic attractor with Cantor transversal structure takes place, collapsing with a further perturbation amplitude increase.

The original Rayleigh–Benard convection is a standard example of the system where bifurcations occur with changing of a control parameter. In this paper we consider the modified Rayleigh–Benard convection problem including radiative effects as well as gas sources on a surface. Such formulation leads to the identification of new type of bifurcations in the problem besides the well-known Benard cells. This problem is very important for mathematics of climate because it proves the occurrence of the climate system tipping point related to greenhouse gas emission into the atmosphere.

The dynamics of the four dissipatively coupled van der Pol oscillator is considered. Lyapunov chart is presented in the parameter plane and its arrangement is discusses. The effect of increase of the threshold for the «oscillator death» regime and the possibility of complete and partial broadband synchronization are revealed. We discuss the bifurcations of tori in the system at large frequency detuning of the oscillators, in particular, quasi-periodic saddle-node and Hopf bifurcations.

In the work the behavior of a van der Pol oscillator with a hard excitation is considered near the excitation threshold under parametrical (multiplicative) Gaussian white noise disturbances, and in a case of the two noise sources presence: parametrical one and additive noise. The evolution of probability distribution is studied when a control parameter and a noise intensity are changed. A comparison of the theoretical results, obtained in the quasi-harmonic approach with the results  of numerical solutions of the oscillator stochastic equations is fulfilled.