Stochastic resonance under two-parameter modulation in a chemical model system

Stochastic resonance (SR) is demonstrated under two-parameter modulation in a model of the photosensitive Belousov-Zhabotinsky reaction in a flow syst em. Light flux and a flow rate are two control parameters in the model, and modulate a focal steady state close to a Hopf bifurcation simultaneously. Addition of noise to the light flux gives rise to SR whose behavior depends on the periods of and phase difference in the two modulations. Compared wi th one-parameter modulation by the light flux, the additional flow rate mod ulation results in both increase and decrease in the resonance, strong reso nance with a period different from that of a signal, or suppressed resonanc e. These computational results are interpreted by a threshold scenario of S R applied to the two-parameter system. The effect of the flow rate modulati on on SR in the photosensitive system is also studied from the viewpoint of the peristaltic effect of a pump.