Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillators driven by an amplitude modulated force

Vibrational and stochastic resonances (VR and SR) in two coupled overdamped anharmonic oscillators subjected to an amplitude modulated force (f + 2g cos Omega t) sin omega t, Omega >= omega are numerically studied. When both low-and high-frequency components are included the system show hysteresis and VR behaviour in the absence of a noise term. The resonance dynamics is characterized using response amplitude, phase portrait and mean residence time. We show the occurrence of SR by varying the noise intensity D in the presence of an amplitude modulated signal. High-frequency periodic force induced VR and noise-induced SR show certain similarities and differences.