  In this work, the multiplier method is extended to obtain a general lower
bound of the exponential decay rate in terms of the physical parameters for
port-Hamiltonian systems in one space dimension with boundary dissipation. The
physical parameters of the system may be spatially varying. It is shown that
under assumptions of boundary or internal dissipation, the system is
exponentially stable. This is established through a Lyapunov function defined
through a general multiplier function. Furthermore, an explicit bound on the
decay rate in terms of the physical parameters is obtained. The method is
applied to a number of examples.
