近日，我院刘恒教授以第一作者在控制与优化理论领域国际顶级期刊《IEEE Transactions on Fuzzy Systems》上发表学术论文：Positivity and Stability Analysis for Fractional-Order Delayed Systems: A T-S Fuzzy Model Approach, 29(4): 929-939, 2021. 该期刊为中科院一区TOP期刊，2020年影响因子为9.517。
This paper investigates positivity, external positivity and asymptotic stability for a large class of incommensurate fractional-order nonlinear systems (FONSs) with bounded multiple time-varying delays by virtue of the T-S fuzzy method. The Laplace transformation technique is used to obtain the solutions of T-S fuzzy FONSs. A sufficient and necessary condition is derived for characterizing (internal) positivity and certain criteria are also provided to guarantee external positivity of FONSs with or without time-varying delays. It is indicated that the positivity of the considered systems is determined purely by system matrices rather than the magnitudes of time-varying delays. Moreover, a sufficient and necessary condition for asymptotic stability of positive FONSs is obtained, and a state-feedback controller is also designed to guarantee that state variables not only converge to the origin asymptotically but also remain non-negative, where the control gain matrix is obtained by solving a LP problem. Three numerical simulation examples are given to expound validity and feasibility of the theoretical results.