Figure 3
From: Investigation of non-uniform airflow signal oscillation during high frequency chest compression
A nonlinear second-order system in the form of an electrical circuit. i is electrical current, and v C is voltage difference between each end of C. The value of the resistor (R) in this figure is dependant on i as well as v C whereas the capacitor (C) and the inductor (L) are dependent only on v C . Vin(t) is a voltage source for this simple circuit system. Nonlinear circuit elements in this circuit imply the nonlinearity of fig. 1 (c).