Develop higher-order averaging for multiplicative linear-feedback forcing
Develop an averaging method that incorporates higher-order terms for the extended Stuart–Landau oscillator with multiplicative periodic forcing of the form A x cos(Ω t), so that the averaged dynamics capture the amplitude variation observed during 1:1 synchronization and resolve the inconsistency with lowest-order averaging, which eliminates the perturbation.
References
Several open questions remain to be examined. Second, when considering a periodic force combined with linear feedback [Eq. esl_mp], the perturbation averages out by the lowest-order averaging method. This is inconsistent with numerical results, in which the amplitude of the oscillator varies during 1:1 synchronization [Fig. \ref{reso_esl_multi_freq} (a)]. This disagreement between analysis and numerical simulation would be solved by an averaging method considering the effects of higher-order terms.