Abstract :
In this paper, the unbounded solutions for the following nonlinear planar system:
x = a+y+ − a−y− + f (t),
y =−b+x+ + b−x− +g(t),
is discussed, where a±,b± are positive constants satisfying
1
√a+b+ +
1
√a+b− +
1
√a−b+ +
1
√a−b− =
4
ω
,
x± = max{±x, 0}, y± = max{±y, 0}, ω ∈ R+ \ Q, f (t),g(t) ∈ L∞[0, 2π] are 2π-periodic functions.
2004 Elsevier Inc. All rights reserved
