Unbounded solutions in asymmetric oscillations

In this paper, the existence of unbounded solutions for the following nonlinear asymmetric oscillator: x^''[email protected]^[email protected]^-=f(t) is discussed, where @a, 3 are positive constants satisfying [email protected][email protected][email protected],, for some @w @? R^+/Q, @?(t) is [email protected] and bounded, @g^+/- = max{+/[email protected], 0}.