Stochastic resonance in a bistable system with global delay and two noises

The global time delay is introduced into a bistable system driven by two noises and a periodic signal. The signal power amplification factor eta is employed to characterise stochastic resonance (SR) of the system. Numerical simulation results indicate the following. (1) For a periodic signal with low frequency (Omega), the typical behaviour of the SR is lowered monotonically by increasing the delay time tau; for moderate Omega, tau enhances the SR behaviour and then weakens it, with a critical value at which the SR is optimum. (2) Multiplicative noise intensity D and additive noise intensity alpha have different influences on the SR performance, viz D enhances the SR monotonically while alpha enforces the SR initially and then restrains it; (3) correlation intensity lambda between the two noises always weakens the SR behaviour of the system.