Abstract
We consider the existence and nonexistence of the positive periodic solutions of the non-autonomous nonlinear Duffing equation with delay and variable coefficients $$ x''(t)-p(t)x'(t)+ q(t)x(t)=\lambda h(t)f(t,x(t-\tau(t)))+r(t), $$ It is shown that the equation has positive periodic solutions under certain conditions and no positive $T-$periodic solution under some other conditions by using a fixed theorem in cones.
Citation
Weigao Ge. Yuji Liu. "On the Positive Periodic Solutions of the Nonlinear Duffing Equations with Delay and Variable Coefficients." Bull. Belg. Math. Soc. Simon Stevin 11 (3) 441 - 455, September 2004. https://doi.org/10.36045/bbms/1093351383
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