“…Therefore, model order reduction becomes important and popular. So far, many effective methods have emerged to reduce the large-scale linear time invariant (LTI) models, such as Krylov subspace method (Grimme, 1997; Yuan et al, 2018), balanced truncation method (Haider et al, 2017; Yang and Jiang, 2020; Zhou et al, 2001), orthogonal decomposition method (Yuan et al, 2018), optimal model order reduction method (Jiang and Xu, 2017; Sato and Sato, 2017; Vasu et al, 2018), and so on.…”