Two examples of ill-posedness with respect to time delays revisited

We revisit two examples of elastic control systems which are stabilized by boundary feedback and then destabilized when time delays occur in the feedback. In the first example, a wave equation with a feedback gain greater than or equal to one, arbitrary divergence rates are obtained for small time delays. In the second example, a Euler-Bernoulli beam, any time delay results in an arbitrary divergence rate.