Non-Newtonian liquids behave very differently: if you stir them slowly, they appear to be a perfectly normal liquid. But if you put pressure on it, it suddenly becomes rock hard. Most liquids we know from daily life are Newtonian: their viscosity does not depend on the pressure applied to such a liquid. With non-Newtonian fluids, however, viscosity does depend on shear rate or deformation history. Non-Newtonian fluids are very common in practice, to list a few: blood, liquid steel, liquid detergent, shampoo, ketchup, lava, quicksand ...

"In my PhD, I offer a theoretical and practical (experimental) framework to test dynamics and motion variations in non-Newtonian fluids," Isabela explains.

"The novelty of the proposed approach is that new tools from mathematics are used to find solutions to current limitations in modeling non-Newtonian fluids," she explains.

"In collaboration with Arcelor Mittal Gent, I specifically focused on modeling the motion properties of liquid steel when external forces are applied to it," she continues.

"Furthermore, I also investigated the production process of medical pills. Indeed, some sub-processes in the production of pills induce changes in, for example, the powder or liquid mixtures that alter the flow conditions of the raw material and cause non-Newtonian characteristics to emerge during the production process," Isabela concludes.

Read a more detailed summary or the entire PhD

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PhD Title: Fractional Order Models Enabling Control Strategies Based on Material Properties

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Isabela Roxana Birs obtained her Bachelor of Science in the Systems Engineering domain, followed by a Master's degree in Advanced Process Control from Technical University of Cluj-Napoca. She has already obtained a PhD degree from the same university in 2021 for the thesis entitled "Fractional order control strategies for poorly damped processes". Her main research interest revolves around fractional calculus and its manifold of applications in modeling and control of various physical phenomena.

In January 2019 she started her PhD at Ghent University with an FWO fellowship.

During her research career she has published 43 papers that are indexed by Web of Science: 14 journal articles, 1 review and 27 proceedings papers. She also wrote 3 book chapters (1 Elsevier, 2 Springer). Her Web Of Science H-Index is 8, accumulating 253 citations since the beginning of her research career in 2017.

Isabela is a finalist (Second place) of the Young Author Award for the paper: “An Interdisciplinary, Low-Cost Methodological Framework for Analyzing Dynamical Material Properties for Control-Related Applications”, awarded in Philadelphia, USA, 2019. Furthermore, she is EU-COST Action no. 15225 mobility funding program winner, supporting a mobility of two weeks in the period September 2-16, 2019 to the research group of Prof. Riccardo Caponneto, University of Catania, Sicily, Italy. She also won 6 other awards from The Executive Agency for Higher Education, Research, Development and Innovation Funding Romania consisting of 2 research mobilities and 4 special prizes for papers published in Q1/Q2 journals.

She is a member of the organizing committee for three international conferences: - The 11th International Federation of Automatic Control (IFAC) Symposium on Biological and Medical Systems, 2021, Belgium - IEEE International Conference on Automation, Quality and Testing, Robotics, Cluj-Napoca, Romania 2022 - International Conference on Fractional Signals and Systems 2015, Cluj-Napoca, Romania.

She is scientific evaluator for more than 10 ISI Q1/Q2 journals such as Journal of Automatica Sinica, ISA Transactions, etc. She is also a guest editor for Fractals and Fractional (Q1 journal) where she is organizing the special issue "Fractional Order Controllers: Design and Applications".

Contact: Isabela Roxana Birs, Dana Copot, Clara-Mihaela Ionescu

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Editor: Jeroen Ongenae - Illustrator: Roger Van Hecke