A General Form of Fractional Derivatives for Modelling Purposes in Practice

In this paper, we propose new mathematical models for the complex dynamics of the world population growth as well as a human body’s blood ethanol concentration by using a general formulation in fractional calculus. In these new models, we employ a recently introduced $\psi-$Caputo fractional derivative whose kernel is defined based on another function. Meanwhile, a number of comparative experiences are carried out in order to verify the models according to some sets of real data. Simulation results indicate that better approximations are achieved when the systems are modeled by using the new general fractional formulation than the other cases of fractional- and integer-order descriptions.