Professor Datko will investigate the effects of time delays on stabilizing boundary controls of some infinite-dimensional systems. Three areas will be considered. (i) The effects of small time delays on stabilizing controls for systems described by hyperbolic partial differential equations. (ii) The robustness of the stability of viscoelastic systems in the presence of time delays vis a vis elastic systems. The former appear, in some cases, to be less sensitive than the latter when time delays are introduced into their damping. Hence viscoelastic systems may serve as more suitable models for flexible structures than elastic systems. (iii) A reexamination of controllability and stabilizability for elastic systems with a view to considering "approximate" definitions of these concepts which are robust with respect to perturbations involving time delays.
