Exponential Dichotomy for Hyperbolic Systems with Periodic Boundary   Conditions
  We investigate evolution families generated by general linear first-order hyperbolic systems in one space dimension with periodic boundary conditions. We state explicit conditions on the coefficient functions that are sufficient for the existence of exponential dichotomies on $\R$ in the space of continuous periodic functions. 
R. Klyuchnyk, I. Kmit, L. Recke
math.AP