Conclusions

Abstract

In this book, the airway tree geometry and morphology was addressed to find the origins of the fractional order appearance in impedance models of the respiratory system. These models pose the characteristic of having a constant phase over a frequency interval, suggesting a frequency independent mechanical efficiency of the lungs (i.e. constant-phase models). After a careful investigation on the existing models from literature for the input impedance, we conclude that the fractional order models may outperform integer-order models in certain frequency intervals. Hence, the natural question arises: why?