The effects of an external signal on internal stochastic resonance in a liquid membrane oscillator

Internal stochastic resonance (ISR) in a liquid membrane oscillator is investigated by varying frequency (ωs) and amplitude (A) of an external signal (ES) in the presence of environment noise. It is found that the enhancement or suppression of ISR depends on frequency and amplitude of ES. In the range of low frequency (0.03-0.12 Hz), ISR appears and noise can transfer energy of ES to IS both for A=0.02 M and for A=0.15 M. In the range of high frequency (0.26-0.32 Hz), there exits an optimal frequency for ES, which is equal to frequency of IS and makes ISR strength reach maximum for A=0.02 M; but ISR disappears for A=0.15 M. At the optimal frequency ωs=0.28 Hz, a critical amplitude Ac for ES is found, less than which, ISR appears, and more than which, ISR disappears