报告题目:SOME STABILITY AND STABILIZATION ISSUES OF TIME DELAY SYSTEMS OF FRACTIONAL AND INTEGER ORDER
报告时间：2022年06月30日15：30-17：00（北京时间）
报告地点：线上腾讯会议（ID: 338-472-833）
报 告 人： Mihailo Lazarevic教授, 贝尔格莱德大学, 塞尔维亚
主 持 人： 孙洪广教授
主办单位：力学与材料学院水力学与流体力学研究所
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报告简介：
Abstract.
The problem of investigation of time delay system has been exploited over many years. Delay is very often encountered in different technical systems, such as electric, pneumatic and hydraulic networks, chemical processes, long transmission lines, etc. The existence of pure time delay, regardless if it is present in the control or/and state, may cause undesirable system transient response, or generally, even an instability. In practice one is not only interested in system stability (e.g. in the sense of Lyapunov), but also in bounds of system trajectories (known as non-Lyaponov stability - finite time stability(FTS)). A system could be stable but still completely useless because it possesses undesirable transient performances. Thus, the analysis of these particular boundedness properties of solutions is an important step, which precedes the design of control signals, when finite time or practical stability control is a concern.
Here, we present further results on Lyapunov stability as well as FTS and stabilization for a given class of integer order and fractional order regular and neutral time-delay systems.
Firstly, we discuss FTS of (non)linear nonhomogeneous perturbed fractional systems with a constant time delay and stabilization of nonlinear nonhomogeneous perturbed fractional systems with time varying delay. Also, some attention is devoted to problem of FTS of a nonlinear nonhomogeneous perturbed fractional system including time-varying delays in state and control which can be given by a nonlinear nonhomogeneous fractional state equation. The stability criteria for the fractional systems with multiple time delays are obtained by using the generalized and classical Gronwall’s approach.
Also, FTS analysis for a class of nonhomogeneous perturbed neutral fractional system with multiple time-varying delays as well as a class of neutral fractional-order time-varying delay systems with nonlinear parameter uncertainties and perturbations were considered. By use of the generalized Gronwall inequality, sufficient conditions for robust FTS for these classes of neutral fractional time-varying delay systems have been proposed. The FTS for nonlinear neutral multi-term fractional order systems with time-varying input and state delays is also investigated. By use of the generalized Gronwall inequality and extended form of the generalized Gronwall inequality, new sufficient conditions for finite-time stability of such systems are obtained. Finally, the simulation results which are related to some class of mechanical systems, are presented to illustrate the effectiveness and applicability of the proposed theoretical results.
Keywords:time-delay system, finite time stability, fractional order, neutral system, stabilization
报告人简介：
Since 2009 Mihailo Lazarević is Full Professor at the University of Belgrade, Faculty of Mech. Eng. – Dep. of Mechanics as well chief of the Laboratory of Applied Mech. He received four degrees from Belgrade University: B. Sc. in Mech. Eng. (aerospace),(1989), B.Sc. in Electrical Eng.,(1991), M.Sc. in Control and System Science Eng.,(1993) and Ph.D. in Mech. Eng. (robotics), (1999).His research activities include robotics, control systems, bioengineering applications, electroviscoelasticity. His current interests are related to application of fractional calculus to modelling and control of complex systems. So far, he published one int. monograph,10 national monographs, 4 chapters in int. monographs, 30 ISI journal papers, 15 papers in international and 12 papers in national journals, 130 conference papers, 2 books, and 2 handbooks. He has over 1203 citations (Scopus) and his H index is 16 and according to Google Scholar he has 2025 citations and H index is 21. He is member of the IUTAM, and serves as reviewer for over 30 int. journals. From 2015-2019 he was President of the Serbian Society of Mechanics. He has been (co-)supervisor or a member of commission for over 35 diploma works, 3MSc Theses and 12 Ph. D. dissertations.