“…The usefulness of techniques for deriving reduced order approximations of high order system has been already accepted due to the advantages of reduced computational effort and increased understanding of original system [5,6]. Consequently, a large number of time-domain (Hankel norm, balance truncation, and Krylov subspace projection) and frequency-domain (Moment matching, Padé approximation, Routh-Padé approximation, and pole clustering methods) system simplification techniques have been developed to suit the different requirements and a variety of numerical approximation are applied to obtain the reduced order model [7].…”