Mihaela Sbarciog

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Material or fluid transportation is a commonly encountered phenomenon in industrial applications, generating variable time delay that makes the design of feedback control loops more difficult. This paper investigates the applicability of MPC (Model Predictive Control) strategies to this type of processes. The experimental setup consists of a heated tank, of(More)
The paper deals with the design of a predictive controller for a wastewa-ter treatment process. In the considered process, the wastewater is treated in order to obtain an effluent having the substrate concentration within the standard limits established by law (below 20 mg/l). This goal is achieved by controlling the concentration of dissolved oxygen to a(More)
In this study, a multivariable control structure is developed to simultaneously control the concentrations of cells and of one of the nutrients in an animal cell cultivation system operated in perfusion. A cascade control structure is considered consisting of (i) an inner loop with a partially linearizing feedback controller, tuned so as to ensure(More)
This paper presents an effective and robust structure for the estimation and control of perfusion cell cultures, in which the cells and glucose concentrations are simultaneously controlled by manipulating the dilution and bleed rates. Firstly, a partially linearizing feedback controller is designed to ensure an approximately linear decoupled dynamics(More)
This paper presents the bifurcation analysis of an anaerobic digestion model, which includes hydrogen production along with methane production. Analytical expressions of the equilibria are given and the conditions for their occurrence are provided. The analytical developments are validated by means of bifurcation diagrams built with specialized continuation(More)
This paper presents a multivariable robust control structure for perfusion animal cell cultures. The control structure assumes a cascade form, where a linearizing feedback controller is used in the inner loop and linear controllers are used in the outer loops, to simultaneously control the cells concentration and the glucose concentration in the bioreactor.(More)
The start-up of anaerobic digestion processes is a complex problem, which determines the entire evolution of the system. In spite of its importance, this issue has not received so far a significant attention. This paper presents two simple startup strategies for an anaerobic digestion process, which have been developed based on the system dynamics. Both(More)
Microorganisms growth processes are encountered in many biotechnological applications. For an increased economic benefit, optimizing their productivity is of great interest. Often the growth is inhibited by the presence in excess of other components. Inhibition determines the occurrence of multiple equilibrium points, which makes the optimal steady state(More)