“…Duffing oscillator [Rajamani & Rajasekar, 2017;Luo & Huang, 2012;Luo & Min, 2011], energy harvesting from sea waves [De Paula et al, 2012;Lenci, 2014] or rigid bodies interacting with a resisting medium [Shamolin, 2009] show a very similar behavior to the pendulum. Also, in other physical realms, it appears that different oscillators can be easily modeled as pendulum-like systems [Blackburn et al, 1987] or show dynamic behavior resembling pendulums [Ruelas & Rand, 2015].…”