We investigate numerically the effects of time delay on the phenomenon of
noise-enhanced stability (NES) in a periodically modulated bistable system. Three types
of time-delayed feedback, including linear delayed feedback, nonlinear delayed
feedback and global delayed feedback, are considered. We find a non-monotonic
behaviour of the mean first-passage time (MFPT) as a function of the delay time
τ, with a maximum in the case of linear delayed feedback and with a minimum
in the case of nonlinear delayed feedback. There are two peculiar values of
τ around
which the NES phenomenon is enhanced or weakened. For the case of global delayed feedback, the increase
of τ
always weakens the NES phenomenon. Moreover, we also show that the amplitude
A and the
frequency Ω
of the periodic forcing play an opposite role in the NES phenomenon, i.e. the increase of
A
weakens the NES effect while the increase of
Ω
enhances it. These observations demonstrate that the time-delayed feedback can be used as
a feasible control scheme for the NES phenomenon.