Leírás
Occurrence of bi- and trirhythmicity (coexistence of two or three stable limit cycles, respectively, with distinctly different periods) has been studied experimentally by applying delayed feedback control to the copper-phosphoric acid electrochemical system oscillating close to a Hopf bifurcation point. With small delay times (tau) the period exhibits a sinusoidal type dependence on tau. However, with relatively large delays for each feedback gain K there exists a critical delay τcrit above which birhythmicity emerges. At very large delays, the dynamics becomes even more complex, and trirhythmicity could be observed. Results of numerical simulations based on a general kinetic model for metal electrodissolution were consistent with the experimental observations. The results are also interpreted by using a simple phase model.