“…In the latter, the author applied Perron‐Frobenius techniques introduced in [
20] and the theory of positive semigroups to establish stability criteria. Recently, using the feedback theory of
‐well‐posed and regular linear systems, the authors in [
9, 19] established the well‐posedness and stability results of structured population systems with unbounded birth process. Unlike the asymptotic behavior, which is well understood, there are no works addressing the controllability properties of age/size‐structured population models with a delayed birth process, to the best of our knowledge.…”