An epidemic SIS model whose coefficient is almost periodic functions is studied. A sufficient condition of existence and uniqueness of positive periodic solution is obtained.
对系数是概周期函数的传染病s IS模型进行了研究，得到了概周期解存在惟一的一个充分条件。
2
By the discretization of spatial variable in the equation, a third-order differential system of equations containing periodic time-varying coefficient is derived.
采用微分求积法对方程中的空间变量进行离散，得到仅含有时间变量的三阶周期系数微分方程组。
3
The reflection coefficient for a periodic structure computed by this method is in good agreement with the result calculated by the propagating matrix method.