THE COEXISTENCE OF PERIODIC, ALMOST-PERIODIC AND CHAOTIC ATTRACTORS IN THE VAN DER POL-DUFFING OSCILLATOR

In this paper are presented the computer simulation and the approximate theoretical analysis of the behaviour of the van der Pol-Duffing forced oscillator at the passage through principal resonance, at increasing and decreasing driving frequency. Almost-periodic oscillations, frequency locking, transition to chaotic motion and the jump from the non-resonant to the resonant state are observed and interpreted in the light of approximate analytical theory and by the use of topological concepts.