Denis de Carvalho Braga

Bifurcation analysis of the Watt governor system

This paper pursues the study carried out by the authors in Stability and Hopf bifurcation in the Watt governor system [14], focusing on the codimension one Hopf bifurcations in the centrifugal Watt governor differential system, as presented in Pontryagins book Ordinary Differential Equations, [13]. Here are studied the codimension two and three Hopf bifurcations and the pertinent Lyapunov stability coefficients and bifurcation diagrams, illustrating the number, types and positions of bifurcating small amplitude periodic orbits, are determined. As a consequence it is found a region in the space of parameters where an attracting periodic orbit coexists with an attracting equilibrium.

DEGENERATE HOPF BIFURCATIONS IN CHUA'S SYSTEM

In this paper we study the local codimension one, two and three Hopf bifurcations which occur in the classical Chuas differential equations with cubic nonlinearity. A detailed analytical description of the regions in the parameter space for which multiple small periodic solutions bifurcate from the equilibria of the system is obtained. As a consequence, a complete answer for the challenge proposed in [Moiola & Chua, 1999] is provided.

More Than Three Limit Cycles in Discontinuous Piecewise Linear Differential Systems with Two Zones in the Plane

In this paper, we study the existence of limit cycles for piecewise linear differential systems with two zones in the plane. More precisely, we prove the existence of piecewise linear differential systems with two zones in the plane with four, five, six and seven limit cycles. From our results we conjecture the existence of piecewise linear differential systems with two zones in the plane having exactly n limit cycles for all n ∈ ℕ.

Hopf Bifurcations in a Watt Governor with a Spring

Abstract This paper pursues the study carried out in [10], focusing on the codimension one Hopf bifurcations in the hexagonal Watt governor system. Here are studied Hopf bifurcations of codimensions two, three and four and the pertinent Lyapunov stability coefficients and bifurcation diagrams. This allows to determine the number, types and positions of bifurcating small amplitude periodic orbits. As a consequence it is found an open region in the parameter space where two attracting periodic orbits coexist with an attracting equilibrium point.

Bifurcation Analysis of a Van der Pol-Duffing Circuit with Parallel Resistor

We study the local codimension one, two, and three bifurcations which occur in a recently proposed Van der Pol-Duffing circuit (ADVP) with parallel resistor, which is an extension of the classical Chuas circuit with cubic nonlinearity. The ADVP system presents a very rich dynamical behavior, ranging from stable equilibrium points to periodic and even chaotic oscillations. Aiming to contribute to the understand of the complex dynamics of this new system we present an analytical study of its local bifurcations and give the corresponding bifurcation diagrams. A complete description of the regions in the parameter space for which multiple small periodic solutions arise through the Hopf bifurcations at the equilibria is given. Then, by studying the continuation of such periodic orbits, we numerically find a sequence of period doubling and symmetric homoclinic bifurcations which leads to the creation of strange attractors, for a given set of the parameter values.

A STUDY OF THE COEXISTENCE OF THREE TYPES OF ATTRACTORS IN AN AUTONOMOUS SYSTEM

In this paper, we study the coexistence of three types of attractors in an autonomous system in ℝ3: an equilibrium point, a limit cycle and a chaotic attractor. We give an analytical proof of the mechanism for the birth of two different types of these attractors.

CONTROLLABLE HOPF BIFURCATIONS OF CODIMENSIONS ONE AND TWO IN LINEAR CONTROL SYSTEMS

Given a linear time-invariant control system, the purpose of this work is to define a four-parameter family of static state feedback such that the corresponding closed-loop control system exhibits controllable Hopf bifurcation of codimensions one and two.

Bifurcation analysis of a model for biological control

In this paper we study the Lyapunov stability and Hopf bifurcation in a biological system which models the biological control of parasites of orange plantations.

Nonlinear analysis in a modified van der Pol oscillator

In this paper we study the nonlinear dynamics of a modified van der Pol oscillator. More precisely, we study the local codimension one, two and three bifurcations which occur in the four parameter family of differential equations that models an extension of the classical van der Pol circuit with cubic nonlinearity. Aiming to contribute to the understand of the complex dynamics of this system we present analytical and numerical studies of its local bifurcations and give the corresponding bifurcation diagrams. A complete description of the regions in the parameter space for which multiple small periodic solutions arise through the Hopf bifurcations at the equilibria is given.

Nonhyperbolic Periodic Orbits of Vector Fields in the Plane Revisited

The main goal of this paper is to present a theory of approximation of periodic orbits of vector fields in the plane. From the theory developed here, it is possible to obtain an approximation to the curve of nonhyperbolic periodic orbits in the bifurcation diagram of a family of differential equations that has a transversal Hopf point of codimension two. Applications of the developed theory are made in Lienard-type equations and in Bazykin’s predator-prey system.