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

# bifurcations

## Equations with the Fermi–Pasta–Ulam and dislocations nonlinearity

Issue. The class of Fermi–Pasta–Ulam equations and equations describing dislocations are investigated. Being a bright representative of integrable equations, they are of interest both in theoretical constructions and in applied research. Investigation methods. In the present work, a model combining these two equations is considered, and local dynamic properties of solutions are investigated. An important feature of the model is the fact that the inﬁnite set of characteristic numbers of the equation linearized at zero consists of purely imaginary values.

## Bifurcations in active predator – passive prey model

Bifurcations were studied numerically in the system of partial differential equations, which is  a one variant of predator-prey models. The mathematical model takes into account spatial  distribution in habitat, active directed predator movements, birth and death process in prey  population. The analysis of possible population dynamics development was performed by two  qualitatively different discrete sampling techniques (Bubnov–Galerkin’s method and grid method).

## Self-organization and bifurcations of dynamical metal cutting system

The problems of nonlinear dynamics of cutting metal are considered in the article. We offer mathematical model of dynamical system that includes a dynamical relation of the cutting process by using turning example. Basic positions of the dynamical relation are the forces dependence of cutting area, the force’s delay of elastic deformation shift of a tool by relative to workpiece, limitations of the cutting forces on clearance face of the tool, dependence of the cutting forces of the cutting velocity.

## Influence of a flexural deformation of a tool on self-organization and bifurcations of dynamical metal cutting system

In the article we offer to consider case of a flexural deformation shifts of a tool when they are essential for nonlinear dynamics of cutting process. This situation is observed for drill deep  holes, because a boring bar has a small values of a flexural stiffness. In that case an angle of cutting  edge reduces and cutting forces increase if the deformation shifts also increased in velocity  direction. The last circumstance becomes occasion for positive feedback that essentially changes  dynamics of the cutting process.

## 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.

## About the history of nonlinear integral equations

The work is dedicated to the history of the theory of nonlinear integral equations, covering a period before the start of the 1930s. By analyzing the specifics of the initial period, authors emphasize that the integral equations (in particular, nonlinear equations) is independent object of research with their own problems, requiring its own system of concepts and own language. As a starting point here A.M.

## Dynamical modes and nonlinear phenomena in modified autooscillatory system with frequency-phase control

In the proposed paper, we investigate the dynamical behavior of the modified system with frequency-phase control, which uses two-channel discriminator in the circuit of phase control and multi-frequency discriminator with periodic nonlinearity in the circuit of frequency control. We consider the case of identical low-pass filters of the third order in the both control circuits. Mathematical model of analyzed frequency-phase system is presented by a nonlinear dynamical system in the four-dimensional cylindrical phase space.

## Nonlinear dynamical models of neurons: Review

Topic. A review of the basic dynamical models of neural activity is presented and individual features of their behavior are discussed, which can be used as a basis for the subsequent development and construction of various configurations of neural networks. The work contains both new original results and generalization of already known ones published earlier in different journals.

## Legacy of Alexander Mikhailovich Lyapunov and nonlinear dynamics

Aim. The aim of the work is to study the scientific heritage of A.M. Lyapunov from the standpoint of nonlinear physics. Fundamental importance Lyapunov’s contribution is determined not only by the methods he created, which became the basis of the mathematical apparatus in the study of nonlinear phenomena, but his ideas and concepts introduced by him contributed to the formation of concepts and principles of nonlinear dynamics. Method. The study is based on an analysis of Lyapunov’s original works with the involvement of existing literature on his scientific heritage.

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