Well-posedness of linear first order Port-Hamiltonian Systems on multidimensional spatial domains

We consider a port-Hamiltonian system on a spatial domain $\Omega \subseteq \mathbb{R}^n$ that is bounded with Lipschitz boundary. We show that there is a boundary triple associated to this system. Hence, we can characterize all boundary conditions that provide unique solutions that are non-increasing in the Hamiltonian. As a by-product we develop the theory of quasi Gelfand triples. Adding ``natural'' boundary controls and boundary observations yields scattering/impedance passive boundary control systems. This framework can be applied to the wave equation, Maxwell equations and Mindlin plate model, and probably many more.