published in International Research Journal on Innovations in Engineering, Science and Technology Journal
full text https://www.researchgate.net/publication/325989325_Retrofitting_Fractional-Order_Dynamics_to_an_Existing_Feedback_Control_System_From_Classical_Proportional-Integral_PI_Control_to_Fractional-Order_Proportional-Derivative_FOPD_Control
keywords control theory; control system analysis; fractional calculus; operational amplifiers; robust control