  This paper explores two instances where dissipation plays a crucial role in
curbing the unbounded energy growth of particles in time-dependent billiards.
The first example involves an elliptical-like billiard with inelastic
collisions between the particle and the boundary. This scenario introduces a
fractional loss of energy upon collision, resulting in the suppression of
unbounded energy growth. The second example examines an oval-like billiard,
where a particle undergoes continuous energy reduction due to a viscous drag
force. Both findings emerged in 2009 from collaborative research with Lyonia
Bunimovich during a visit to the Georgia Institute of Technology.
