Mahmoud M.S.Xie L.Faculty of EngineeringMSA UniversityAmer StreetMesaha SquareDokkiEgypt; Sch. of Elec. and Electron. Eng.Nanyang Technological UniversityNanyang AvenueSingapore 639798Singapore2020-01-252020-01-2520011024123Xhttps://doi.org/10.1155/S1024123X01001739https://www.hindawi.com/journals/mpe/2001/419527/ScopusIn this paper, we investigate the robust passivity analysis and synthesis problems for a class of uncertain time-delay systems. This class of systems arises in the modelling effort of studying water quality constituents in fresh stream. For the analysis problem, we derive a sufficient condition for which the uncertain time-delay system is robustly stable and strictly passive for all admissible uncertainties. The condition is given in terms of a linear matrix inequality. Both the delay-independent and delay-dependent cases are considered. For the synthesis problem, we propose an observer-based design method which guarantees that the closed-loop uncertain time-delay system is stable and strictly passive for all admissible uncertainties. Several examples are worked out to illustrate the developed theory.EnglishDesignObserverPassivityTime-delay systemsUncertaintiesWater qualityArticlehttps://doi.org/10.1155/S1024123X01001739