Traveling wave oscillatory patterns in a signed Kuramoto-Sivashinsky equation with absorption

In this paper, a proof of a part of a conjecture raised in [Galaktionov and Svirshchevskii. Exact solutions and invariant subspaces of nonlinear partial differential equations in mechanics and physics. Chapman & Hall] concerning existence and global uniqueness of an asymptotically stable periodic orbit in a fourth-order piecewise linear ordinary differential equation is presented. The fourth-order equation comes from the study of traveling wave patterns in a signed Kuramoto-Sivashinsky equation with absorption. The proof is twofold. First, the problem of solving for the periodic orbit is transformed into a zero finding problem on R4, which is solved with a computer-assisted proof based on Newton's method and the contraction mapping theorem. Second, the rigorous bounds about the periodic orbit in phase space are combined with the theory of discontinuous dynamical systems to prove that the orbit is asymptotically stable.