A NOTE ON THE EXISTENCE OF LIMIT CYCLES FOR PLANAR SYSTEMS WITH BOUNDED NONLINEARITIES AND phi-LAPLACIAN

This paper deals with the nonlinear differential equation (phi((x)overdot))(center dot) + Sigma(i=1) f(2j-1) (x) (phi((x)overdot))(2j-1) + g(x) = 0, where the range of the function phi is bounded. A result concerning existence of limit cycles are presented. The proof of our result is based on phase plane analysis of the equivalent system with the Poincare-Bendixon theorem. Finally an example is given to illustrate our result.