“…In particular, various aspects of dynamics of forced oscillators have been studied in [39], [22], [6], [41], [42], [32], [55], [60], [56], [7], including applications to accurate modelling and optimization of parameters of power electronics systems in the presence of the ferroresonance phenomenon [57] and input-to-state stability of control systems. Cycles stemming from the Hopf bifurcation in a model of Van der Pol type oscillator, a network of such oscillators and other systems with hysteresis were studied in [1], [3], [33], [20], [21]. In the electrical circuitry context, this model describes a circuit consisting of an LCR contour and a negative feedback loop (which can be implemented, for instance, by using tunnel diodes) and involving a ferromagnetic core in the inductor.…”