Initially he worked at the University of Maryland, College Park, then in 1983 he joined Office of Naval Research (ONR) and started their nonlinear dynamics program in 1984. He subsequently went on to head their physics division, before being named ONR's chief scientist for nonlinear science. His contributions to nonlinear dynamics and statistical physics include the publication of over 200 papers, editorship of over 20 books, and the organization of over 30 conferences. In 2008, he took up the Kinnear Chair in Physics at the US Naval Academy, Annapolis, United States. In 2021 published "An Unbounded Experience in Random Walks with Applications" (World Scientific Pub)