Lecture

Special Types of Systems: Limit Cycles

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In course

PHYS-460: Nonlinear dynamics, chaos and complex systems

The course provides students with the tools to approach the study of nonlinear systems and chaotic dynamics. Emphasis is given to concrete examples and numerical applications are carried out during the exercise sessions. ...

Description

This lecture covers special types of systems, focusing on gradient systems and limit cycles. It explains the properties of gradient systems and the conditions for equilibrium points. The instructor discusses the stability of equilibrium points and the concept of limit cycles in detail, emphasizing the behavior of trajectories. The lecture also delves into the Poincaré-Bendixson theorem and the implications of closed orbits in phase space. Furthermore, it explores the phenomenon of homoclinic orbits and the criteria for the existence of closed orbits. The session concludes with a study of chaotic behavior in systems, particularly the Transcritical bifurcation and Pitchfork bifurcation.

Instructor

Paolo Ricci

Paolo Ricci earned his masters degree in nuclear engineering at the Politecnico di Torino, Turin (Italy) in 2000. His doctoral studies were conducted at the Los Alamos National Laboratory, with focus on kinetic simulation of magnetic reconnection in the Earth's magnetotail. He spent two-and-a-half years as a postdoctoral researcher at Dartmouth College's Department of Physics and Astronomy, where he worked on gyrokinetic simulations of the Z pinch. He joined the EPFL's Swiss Plasma Center (SPC), as a EURATOM fellow in 2006, was named Tenure Track Assistant Professor in June 2010, and Associate Professor in August 2016. He is at the head of the SPC theory group. Paolo Ricci is the recipient of the 2016 Section de Physique Teaching Prize and of the 2021 Craie d'Or award from the EPFL physics bachelor students.

Official source

Ontological neighbourhood

Systems science and engineering

Systems theory: Chaos theory

Related concepts (32)

Bifurcation theory

Bifurcation theory is the mathematical study of changes in the qualitative or topological structure of a given family of curves, such as the integral curves of a family of vector fields, and the solutions of a family of differential equations. Most commonly applied to the mathematical study of dynamical systems, a bifurcation occurs when a small smooth change made to the parameter values (the bifurcation parameters) of a system causes a sudden 'qualitative' or topological change in its behavior.

Sequence space

In functional analysis and related areas of mathematics, a sequence space is a vector space whose elements are infinite sequences of real or complex numbers. Equivalently, it is a function space whose elements are functions from the natural numbers to the field K of real or complex numbers. The set of all such functions is naturally identified with the set of all possible infinite sequences with elements in K, and can be turned into a vector space under the operations of pointwise addition of functions and pointwise scalar multiplication.

Banach space

In mathematics, more specifically in functional analysis, a Banach space (pronounced ˈbanax) is a complete normed vector space. Thus, a Banach space is a vector space with a metric that allows the computation of vector length and distance between vectors and is complete in the sense that a Cauchy sequence of vectors always converges to a well-defined limit that is within the space. Banach spaces are named after the Polish mathematician Stefan Banach, who introduced this concept and studied it systematically in 1920–1922 along with Hans Hahn and Eduard Helly.

Fréchet space

In functional analysis and related areas of mathematics, Fréchet spaces, named after Maurice Fréchet, are special topological vector spaces. They are generalizations of Banach spaces (normed vector spaces that are complete with respect to the metric induced by the norm). All Banach and Hilbert spaces are Fréchet spaces. Spaces of infinitely differentiable functions are typical examples of Fréchet spaces, many of which are typically Banach spaces.

Pitchfork bifurcation

In bifurcation theory, a field within mathematics, a pitchfork bifurcation is a particular type of local bifurcation where the system transitions from one fixed point to three fixed points. Pitchfork bifurcations, like Hopf bifurcations, have two types – supercritical and subcritical. In continuous dynamical systems described by ODEs—i.e. flows—pitchfork bifurcations occur generically in systems with symmetry. The normal form of the supercritical pitchfork bifurcation is For , there is one stable equilibrium at .

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