Fig. 1:
(Colour online) Domains describing the 1 : 1 frequency-locked (resonant) and unlocked oscillations above the Hopf bifurcation (μ > 0), in a parameter space of detuning (ν) and forcing magnitudes for (a) parametric forcing, γp > 0, γa = 0 and (b) additive forcing, γp = 0, γa > 0. The bottom panel describes the resonant region (shaded area), while the top panels describe the amplitudes of resonant solutions and unlocked oscillations (light dashed lines) at two distinct γ values (γp = 0.1, 0.25, γa = 0.005, 0.08) as a function of ν; solid lines mark stable solutions, and the dashed line in the bottom panel of (a) marks the locus of points at which the nontrivial solutions bifurcate. Equation (3) was solved with parameters: μ = 0.1 and (a) ωc = 0.5, (b) ωc = 1.