In this paper a model reference-based adaptive parameter estimator for a wide class of hyperbolic distributed parameter systems is
considered. The proposed state and parameter estimator can handle hyperbolic systems in which the damping sesquilinear form may
not be symmetric (or even present) and a modification to the standard adaptive law is introduced to account for this lack of symmetry
(or absence) in the damping form. In addition, the proposed scheme is modified for systems in which the input operator, bounded or
unbounded, is also unknown. Parameters that are slowly time varying are also considered in this scheme via an extension of finite
dimensional results. Using a Lyapunov type argument, state convergence is established and with the additional assumption of
persistence of excitation, parameter convergence is shown. An approximation theory necessary for numerical implementation is
established and numerical results are presented to demonstrate the applicability of the above parameter estimators.