The number of limit cycles of Josephson equation

Xiangqin Yu, Hebai Chen, Changjian Liu

In this paper, the existence and number of non-contractible limit cycles of the Josephson equation $\beta \frac{d^2\Phi }{d{t}^2}+(1+\gamma \cos \Phi )\frac{d\Phi }{dt}+\sin \Phi =\alpha$ are studied, where $ϕ\…