  Analysis and resilient design of Cyber-physical Systems have greatly
benefited from energy based concepts of passivity and dissipativity. Recently,
there has been much research devoted to the use of passivity indices in
different components of Cyber-physical systems. Passivity indices are measures
of passivity, indicating how passive a system is or how far is it from being
passive and generalize passivity based methods to systems that might not be
passive. In this paper, we will review recent advances in the use of passivity
indices in Cyber-physical systems. We will overview how the indices have been
defined and applied to different components of Cyber-physical systems and how
they are used in the resilient design of compositional Cyber-physical systems.
