Graduate School in Nonlinear Science

Sponsored by The Danish Research Agency

MIDIT                              OFD                          CATS
Modelling, Nonlinear Dynamics      Optics and Fluid Dynamics    Chaos and Turbulence Studies
and Irreversible Thermodynamics    Risø National Laboratory     Niels Bohr Institute and 
Technical University of Denmark    Building 128                 Department of Chemistry
Building 321                       P.O. Box 49                  University of Copenhagen 
DK-2800 Lyngby                     DK-4000 Roskilde             DK-2100 Copenhagen Ø
Denmark                            Denmark                      Denmark


Francis C. Moon
Cornell University,

MIDIT-seminar 501

Friday, November 16, 2001, 14.00 h
at IMM, Bldg. 305, Room 053, DTU

Abstract: This lecture will describe methods for identifying nonlinear bifurcation models for problems with autonomous generation of limit cycle dynamics from experimental data. Two techniques will be described; one based on the classical harmonic balance method and least squares ideas, and the other based on center manifold theory and normal forms ideas from nonlinear dynamical systems. These methods have been applied to a nonlinear electrical circuit as well as self-excited motions in fluid-structure dynamics. The unique difficulty that is addressed in these methods is how to capture the subcritical bifurcation structure of the limit cycle behavior. This difficulty is solved by using constraints from center manifold analysis on the least squares problem.