# Nonlinear dynamics

lphys2114  2019-2020  Louvain-la-Neuve

Nonlinear dynamics
Note from June 29, 2020
Although we do not yet know how long the social distancing related to the Covid-19 pandemic will last, and regardless of the changes that had to be made in the evaluation of the June 2020 session in relation to what is provided for in this learning unit description, new learnig unit evaluation methods may still be adopted by the teachers; details of these methods have been - or will be - communicated to the students by the teachers, as soon as possible.
5 credits
22.5 h + 22.5 h
Q1
Teacher(s)
Language
English
Prerequisites
LMAT1122 and LMAT1261 for the studentsenrolled in the Bachelor in physicswho wish to follow this teaching unitwithin theadditional module in physics.
Main themes
This teaching unit is an introduction to the concepts and methods of the theory of dynamical systems as well as its application to physics, chemistry, biology and engineering.
Aims
 At the end of this learning unit, the student is able to : 1 a.     Contribution of the teaching unit to the learning outcomes of the programme (PHYS2MA)   1.1, 1.3, 1.4, 2.1, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6   b.     Specific learning outcomes of the teaching unit   At the end of this teaching unit, the student will be able to :   1.    use mathematical tools to characterise the properties of discrete and continuous non-linear systems; 2.    characterise the chaotic dynamics of a system.

The contribution of this Teaching Unit to the development and command of the skills and learning outcomes of the programme(s) can be accessed at the end of this sheet, in the section entitled “Programmes/courses offering this Teaching Unit”.
Content
The teaching unitprovides the student with an introduction to the mathematical theory of dynamical systems and its applications to problems of physics, chemistry, biology and engineering.

The following topics are covered by the teaching unit:
1.  Basic concepts: definition of a dynamical system, examples of continuous and discrete dynamic systems, hyperbolic points of equilibrium and stability, bifurcations.
2.  Discrete chaotic systems: chaos and sensitivity to initial conditions, itineraries, topological conjugation, Lyapunov exponents, the logistic map.
3.  Linearisation, stable and unstable manifoldsthe dynamics of linear systems, classification of two-dimensional fixed points, linearisation around hyperbolic fixed points, stable and unstable manifolds, perturbative analysis;
4.  The horseshoe mapintersections of stable and unstable manifolds, homoclinic points, horseshoe and chaos, Cantor sets;
5.  The Poincaré-Bendixon theorem: trapping regions, limit cycles and limit sets, the Poincaré map, the Poincaré-Bendixon theorem, applications (existence of periodic orbits, Liénard systems).
6.  Ergodic theory: the concept of ergodicity, relations with statistical mechanics, Poincaré's reccurrence theorem, ergodic theorems, examples and applications.
Teaching methods
The learning activities consist of lectures, exercise sessions and a personal project.
The lectures introduce fundamental concepts of the theory of nonlinear systems and their motivation through concrete examples from various scientific disciplines.
The main objective of the exercise sessions is the application of the theory to concrete examples.
Evaluation methods
The evaluation is based on a written exam. It deals with the application of the theory of non-linear systems to concrete examples. It tests the student's knowledge and hisunderstanding of the notions seen in the theoretical course, the mastery of calculation techniques and the coherent presentation of this analysis.
Online resources
The MoodleUCL website of this teaching unit contains a detailed plan of the covered topics, a complete bibliography, exercise sheets and a collection of exam subjects from past years.
Bibliography
• K.T. Alligood, T.D. Sauer, J.A. Yorke, Chaos. An introduction to dynamical systems. Springer-Verlag (2008).
• M.W. Hirsch, S. Smale, R.L. Devaney, Differential equations, dynamical systems, and an introduction to chaos. Academic Press (2013).
• S.H. Strogatz, Nonlinear dynamics and chaos. Westview Press (2015).
• M. Tabor, Chaos and integrability in non-linear dynamics : an introduction. J. Wiley & Sons (1989).
Faculty or entity

#### Programmes / formations proposant cette unité d'enseignement (UE)

Title of the programme
Sigle
Credits
Prerequisites
Aims
Master [120] in Mathematics

Master [60] in Physics

Master [120] in Statistic: General

Master [120] in Physics