ED Mathématiques et Informatique
Stabilization of systems describing the motion of rigid bodies interacting with a fluid
by Zhuo XU (IMB - Institut de Mathématiques de Bordeaux)
The defense will take place at 10h00 - Salle de conférence Institut de Mathématiques de Bordeaux, A33, 351 Cr de la Libération, 33400 Talence, France
in front of the jury composed of
- Marius TUCSNAK - Professeur des universités - Université de Bordeaux - Directeur de these
- Christophe PRIEUR - Directeur de recherche - CNRS / GIPSA-lab / Université Grenoble Alpes - Rapporteur
- Amina MECHERBET - Maîtresse de conférences - Université Paris Cité / IMJ-PRG - Examinateur
- Ping LIN - Professeure des universités - School of Mathematics and Statistics, Northeast Normal University - Examinateur
- Sylvain ERVEDOZA - Directeur de recherche - Institut de Mathématiques de Bordeaux (CNRS / Université de Bordeaux) - Examinateur
- Takéo TAKAHASHI - Directeur de recherche - Inria Nancy – Grand Est / Institut Élie Cartan de Lorraine - Examinateur
This thesis is devoted to the analysis and control of systems describing the motion of a rigid body in a viscous fluid. The main mathematical difficulty lies in the presence of moving interfaces: the fluid domain depends on the unknown motion of the rigid body and must therefore be determined as part of the solution. The models under consideration fall into two classes: floating-body systems, in which the solid interacts with the free surface of the fluid, and immersed-body systems, in which the solid is completely surrounded by the fluid. Part I is devoted to a linearized fluid--solid interaction system describing the coupling between a viscous shallow-water flow in an unbounded domain and the vertical motion of a floating body. We prove that this coupled system is well-posed in an appropriate Hilbert space. We then consider the associated infinite-horizon linear--quadratic control problem. Even though the unbounded spatial domain rules out exponential stability of the uncontrolled semigroup, we establish the well-posedness of the control system and derive a Riccati-based feedback characterization of the optimal control by relying on LQR theory for strongly stable systems. In Part~II, we consider a two-dimensional fluid--rigid body interaction system, in which a rigid disk moves inside a circular cavity filled with a viscous incompressible fluid. The coupled dynamics are governed by the incompressible Navier--Stokes equations and Newton's second law. We prove that collision between the inner disk and the outer boundary cannot occur in finite time, without imposing any apriori verticality assumption on the trajectory of the inner disk. As a consequence, we obtain the global existence and uniqueness of strong solutions. Part~III is devoted to a one-dimensional fluid--particle model, which serves as a reduced free-boundary system retaining the essential features of viscous fluid--solid interaction models. We design a proportional feedback law acting on the particle and prove the global well-posedness of the corresponding closed-loop system. Moreover, we show that the closed-loop system achieves global exponential stabilization of the particle to any prescribed equilibrium position in the interior of the fluid domain. A key ingredient is the existence of a uniform positive lower bound on the distance between the particle and the boundary, which excludes collision and ensures global-in-time control of the moving interface. We further establish a robustness result, in the sense of a type of input-to-state stability (ISS), thereby quantifying the effect of external disturbances on the system.
ED Sciences Chimiques
Polypeptide-based long-acting injectable formulation for the sustained release of therapeutic peptides
by Valentin MAROT (Laboratoire de Chimie des Polymères Organiques)
The defense will take place at 14h00 - PA-01 ENSMAC 16, Av. Pey Berland, 33600 Pessac, France
in front of the jury composed of
- Sébastien LECOMMANDOUX - Professeur des universités - Université de Bordeaux - Directeur de these
- Colin BONDUELLE - Directeur de recherche - LCPO, CNRS/Université de Bordeaux/Bordeaux INP - CoDirecteur de these
- Jean-Paul CHAPEL - Directeur de recherche - CRPP - Examinateur
- Gaëlle LE FER - Chargée de recherche - Unité Matériaux et Transformations CNRS UMR 8207 - Université de Lille - Examinateur
- Juergen SIEPMANN - Professeur des universités - Université de Lille - Examinateur
- Tjasa VRLINIC - Experte - MedinCell - Examinateur
- Benjamin NOTTELET - Professeur des universités - Département des Polymères pour la santé et les Biomatériaux – PHBM Institut de Biomolécules Max Mousseron (IBMM) CNRS UMR 5247 - Rapporteur
- Tina VERMONDEN - Professeure des universités - Utrecht University-Pharmaceutics - Rapporteur
Polypeptide-based polymers are particularly attractive owing to their biocompatibility, biodegradability and ability to exhibit unique secondary structures. Ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs) is commonly used to synthesize such bioinspired polymers on a large scale. These poly(amino acids) (PAAs) provide a versatile platform for designing innovative biomaterials, supported by the broad range of natural and non-natural amino acid-derived NCAs. This PhD work aims at developing polypeptide-based in situ forming depot (ISFD) to be used as long-acting injectable (LAI) formulation for the sustained release of a model therapeutic peptide. Polypeptide-based block copolymers were rationally designed and synthesized, and their formulations systematically investigated to rationalize the relationship between polymer structure and in vitro release behavior. The most promising ISFD formulations were evaluated in an in vivo pharmacokinetic study in rats. Finally, injectable polypeptide-based hydrogels were also proposed as a solvent-free LAI formulation alternative.
ED Droit
A new approach to the principle of the primacy of European Union law in light of American supremacy
by Véronique SPINOSI-LASCAUT (CENTRE DE RECHERCHES ET DE DOCUMENTATION EUROPÉENNES ET INTERNATIONALES)
The defense will take place at 14h00 - Amphithéâtre Gérard Aubin Institut Droit et Économie de Périgueux Université de Bordeaux CS 21201 Rond point Suzanne Noël 24019 Périgueux Cedex
in front of the jury composed of
- Marie-France VERDIER - Maîtresse de conférences - Université de Bordeaux - Directeur de these
- Francette FINES - Professeure - Sciences Po Toulouse - Rapporteur
- Olivier DUBOS - Professeur des universités - Université de Bordeaux - Examinateur
- Hiam MOUANNÈS - Maîtresse de conférences - Université Toulouse Capitole - Rapporteur
Given that the Court of Justice of the European Union and the United States Supreme Court are tasked with ensuring the proper application of the laws that established them, this observation raises the question of whether these courts are able to maintain the preeminent position that is due to them: European Union law and American law. Primacy is to the European Union what supremacy is to the United States, and if a place had to be assigned to these principles, it would be the preeminent one, since without them, EU law and American law could not prevail within the Member States and federated states. However, their methods of achieving this differ because, in the areas under their jurisdiction, the Member States of the European Union remain true to their identity while respecting the spirit of the Community, whereas the American federated states are subject solely to the will of the federal government. Primacy applies when EU law conflicts with national law because, in areas devolved to the European Union by the treaties, the former must prevail over the latter. Conversely, supremacy imposes US law in areas where only the federal government is authorized to intervene under the US Constitution, meaning that no federated state can claim the right to legislate in its place. Even if these principles do not appear to have the same force due to their origins, they guarantee the capacity of the European Union and the United States to manage, respectively, matters common to the Member States and the federated states. Two courts enable the achievement of this objective: the Court of Justice of the European Union and the Supreme Court of the United States, although not in an absolute sense, since they must balance the legal certainty that must be ensured within the Member States and the federated states. Their role is to ensure the protection of primacy and supremacy, and in this sense, they both possess the ultimate right to have the final say. This prerogative allows both courts to apply their principles as they see fit, in light of the law they are responsible for upholding. Consequently, primacy and supremacy are relative, determined solely by the will of each court, which necessitates the absolute nature of the primacy and supremacy associated with them as decision-makers. However, the two courts do not achieve this result through identical procedures, and the significance of this difference demonstrates that it is not necessary to be a federal state to have the power that stems from it recognized. It is true that federalism allows the United States Supreme Court to impose its vision of supremacy with greater leverage. However, even without this advantage, the Court of Justice of the European Union manages to do the same with regard to primacy, employing both diplomacy and determination. Thus, the essential role of the preliminary ruling procedure and the articulation of primacy with the constitutional identity of the Member States must be emphasized. Faced with the attitude of these States, the Court of Justice reacts with the prohibition of ultra vires review and European sanctions. Nevertheless, the Court is both diplomatic and implacable, taking into account the situation of the Member State concerned while providing unwavering justification for its decision in order to avoid being overruled. On the other hand, this diplomacy is unnecessary for the Supreme Court because, by virtue of the constitutional recognition of supremacy, it does not have to legitimize it in the eyes of the federated States, which allows it to maintain American law in the place that the Constitution unquestionably grants it.