Scientific Publications of the University of Toulouse II Le Mirail
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Observed-based exponential stability of the fractional heat equation
No full textInternational audienceIn this work, the exponential stability of the nonlocal fractional heat equation is studied. The fractional Laplacian is defined via a singular integral. Using the spectral properties of the fractional Laplacian and a state-decomposition. The feedback control is build taking account the first N modes and an observer defined via a bounded operator. Different kind of configurations are studied to mention, interior controller and interior observation, interior controller and exterior observation. Using the recent result about simplicity of the eigenvalues \cite{fall2023generic}, some of our stabilization results are valid for s ∈ (0, 1), in particular for s ∈ (0, 1/2) in which case the fractional heat equation is not null controllable
On the penalization by the perimeter in shape optimization applied to Dirichlet inverse obstacle problem
No full textInternational audienceThis paper is devoted to the understanding of regularization process in the shape optimization approach to the so-called Dirichlet inverse obstacle problem for elliptic operators.More precisely, we study two different regularization of the very classical shape optimization approach consisting in minimizing a mismatched functional. The first one is an implicit regularization when working in the class of inclusion having a uniform ε-cone property, a natural class in shape optimization. As this regularity is not trivial to guarantee numerically, we discuss the regularization by perimeter penalization. We show that this second regularization provides a stability gain in the minimization process
A novel perspective on denoising using quantum localization with application to medical imaging
No full textInternational audienceBackground noise in many fields such as medical imaging poses significant challenges for accurate diagnosis, prompting the development of denoising algorithms. Traditional methodologies, however, often struggle to address the complexities of noisy environments in high dimensional imaging systems. This paper introduces a novel quantum-inspired approach for image denoising, drawing upon principles of quantum and condensed matter physics. Our approach views medical images as amorphous structures akin to those found in condensed matter physics and we propose an algorithm that incorporates the concept of mode resolved localization directly into the denoising process. Notably, our approach eliminates the need for hyperparameter tuning. The proposed method is a standalone algorithm with minimal manual intervention, demonstrating its potential to use quantum-based techniques in classical signal denoising. Through numerical validation, we showcase the effectiveness of our approach in addressing noise-related challenges in imaging and especially medical imaging, underscoring its relevance for possible quantum computing applications
La condition au bord de Neumann pour le schéma de Lax-Wendroff bi-dimensionnel. II
No full textInternational audienceWe study the stability of a two-dimensional Lax-Wendroff scheme in a quarter-plane. Following our previous work, we aim here at adapting the energy method in order to study second order extrapolation boundary conditions. We first show on the one-dimensional problem why modifying the energy is a necessity in order to obtain stability estimates. We then study the two-dimensional case and propose a modified energy as well as second order extrapolation boundary and corner conditions in order to maintain second order accuracy and stability of the whole scheme, including near the corner
Agile Interception of a Flying Target using Competitive Reinforcement Learning
No full textInternational audienceThis article presents a solution to intercept an agile drone by another agile drone carrying a catching net. We formulate the interception as a Competitive Reinforcement Learning problem, where the interceptor and the target drone are controlled by separate policies trained with Proximal Policy Optimization (PPO). We introduce a high-fidelity simulation environment that integrates a realistic quadrotor dynamics model and a low-level control architecture implemented in JAX, which allows for fast parallelized execution on GPUs. We train the agents using low-level control, collective thrust and body rates, to achieve agile flights both for the interceptor and the target. We compare the performance of the trained policies in terms of catch rate, time to catch, and crash rate, against common heuristic baselines and show that our solution outperforms these baselines for interception of agile targets. Finally, we demonstrate the performance of the trained policies in a scaled real-world scenario using agile drones inside an indoor flight arena
Les trains de nuit : un service de transport incomparable ?
No full textInternational audienceEn France comme en Europe, les trains de nuit ont entamé un long déclin avant de connaître une relance au milieu des années 2010. À l’image de la suppression controversée des trains Paris-Berlin et Paris-Vienne, annoncée pour décembre 2025, ce retour en grâce apparaît toutefois fragile. Quels jeux d’acteurs se cachent derrière ces multiples secousses ? Comment leurs décisions ont-elles conduit à la desserte territoriale actuelle ? Ces trains peuvent-ils constituer une véritable alternative modale dans une perspective de transition écologique, ou sont-ils condamnés à demeurer une offre ferroviaire de niche ?Entre hype médiatique et déliquescence du matériel, entre montée en gamme et enjeux d’aménagement, nous verrons quel peut être l’avenir de ces trains si particuliers
Paleolimnological Records in the Northern Pampa Plain
No full textInternational audienceIn the Northern Pampa plain (NPP, 30° and 34°S), terrain depressions generated by neotectonics were occupied by shallow lakes preserving long-lasting paleolimnological records. The most significant are the sediments of Laguna Mar Chiquita (LMCh, 30°S/62°W), spanning from the Late Pleistocene to the present. At the southern edge of the NPP, the record from Laguna Melincué (LMe, 33°S/ 61°W) comprises paleoenvironmental evidence for the Late Holocene. The evolution of both lake systems has been reconstructed using a multi-proxy approach onwell-dated sediment cores, including analyses of stable isotopes, pigments, diatoms, geochemistry, paleoenvironmental magnetism and microfacies. This chapter synthesises the available reconstructions of both sites, along with an analysis of the main methodologies developed during the last twenty years of research. Particularly, the abrupt shifts of lake levels and associated deposits are explored, emphasising the transformation of ephemeral saline/hypersaline lakes and playa lakes to subsaline/saline perennial systems. A special focus is set on disentangling the overlapping signal of anthropogenic activity to the natural hydroclimate oscillations imprinted in the sedimentary record of LMCh over the last fifty years. This review highlights thevalue of Northern Pampa lacustrine records for inspecting past regional hydroclimate and its implications for South American Monsoon variability
Representing Food Waste in Ontologies: A Role-Based Account
No full textInternational audienceFood waste attracts growing research interest because it has a significant impact on our society and the environment. There is nonetheless no general consensus about the meanings of the terms "food loss" and "food waste". To address this issue, this paper aims to provide an ontological analysis of food waste with a focus on FoodOn: an ontology of food and food production that is developed in compliance with the upper ontology Basic Formal Ontology (BFO). We propose the notion of "food material waste" and characterize it in terms of bearing a realized "food waste role". The basic idea is that food waste has a relevant sociotechnical dimension and its relational nature can be analyzed in terms of roles in BFO because they are inherently relational. We also discuss this role-based account of food waste in connection with role-based approaches to food (material) and food products as well as with a list of eight criteria for defining food waste proposed recently by A. Borghini and N. Piras.</div
« C'est la justice que je demande. » Stratégies, représentations et agentivité des hommes et des femmes autochtones dans la justice coloniale (vice-royauté du Pérou, XVIe-XVIIe siècles)
No full textBased on a vast selection of textual material including judicial and notarial documents, this work aims to offer a new, more nuanced understanding of the diversity of the indigenous Andean world in the aftermath of Spanish colonisation and its consequences. The process of socio-racial categorisation at the heart of the colonial system established legal, fiscal and social differentiation that severely limited the ability of indigenous populations to act and represent themselves, i.e. to speak for themselves, in the judicial sphere. However, thanks to a certain degree of leeway and the social diversity of the indigenous world, the latter demonstrated great inventiveness and agency in seizing colonial legal and judicial tools. It is from this perspective that this thesis seeks to give voice and space to the multiple strategies used by indigenous populations, based on their social status, gender, place of residence and other factors, to represent themselves and speak on their own behalf. The issue of gender deserves particular attention, as indigenous women find themselves at the intersection of several lines of pressure. Reflection on gender also allows us to bring together the fields of intimacy, family, sexuality and religion, and to cross-reference them with the judicial axis and the question of representation.Basado en un amplio corpus textual compuesto por documentos judiciales y notariales, el presente trabajo pretende ofrecer una nueva y más matizada comprensión de la diversidad del mundo indígena andino después de la colonización española y sus consecuencias. El proceso de categorización socioracial en que se funde el sistema colonial impone una diferenciación jurídica, fiscal y social que limita la capacidad de los indígenas a actuar y representarse (o autorepresentarse), es a decir llevar su propia palabra en el campo judicial. No obstante, la existencia de un margen de negociación y la diversidad social del mundo indígena andino demuestran la gran inventividad de las poblaciones indígenas para apropiarse de las herramientas jurídicas y judiciales coloniales. Desde esta perspectiva, la tesis presentada busca devolver la voz y el lugar a las múltiples estrategias utilizadas por las poblaciones indígenas, según su estatus social, su género, su lugar de residencia, entre otros factores, para autorrepresentarse y hablar en su propio nombre. El eje de género merece una atención particular, ya que las mujeres indígenas se sitúan en la intersección de múltiples líneas de presión. La reflexión sobre el género permite asimismo convocar los ámbitos de lo íntimo, lo familiar, lo sexual y lo religioso, y cruzarlos con el eje judicial y la cuestión de la representación.À partir d’un vaste corpus textuel composé de documents judiciaires et notariés, le présent travail entend offrir une nouvelle compréhension plus nuancée de la diversité du monde autochtone andin au lendemain de la colonisation espagnole et des conséquences de celle-ci. Le processus de catégorisation socio-raciale au cœur du système colonial met en place une différenciation juridique, fiscale et sociale qui limite fortement la capacité des populations autochtones à agir et à s’autoreprésenter, c’est-à-dire à porter leur propre parole, dans le champ judiciaire. Toutefois, tant par l’existence d’une certaine marge de manœuvre que par la diversité sociale du monde autochtone, ce dernier fait preuve d’une grande inventivité et d’agentivité pour se saisir des outils juridiques et judiciaires coloniaux. C’est dans cette perspective que la thèse présentée cherche à redonner voix et place aux multiples stratégies utilisées par les populations autochtones en fonction de leur statut social, de leur genre, de leur lieu de vie, entre autres facteurs, pour s’autoreprésenter et parler en leur nom. L’axe du genre mérite une attention particulière, en ce que les femmes autochtones se situent à l’intersection de plusieurs lignes de pression. La réflexion sur le genre permet également de convoquer les champs de l’intime, du familial, du sexuel et du religieux, et de les croiser avec l’axe judiciaire et la question de la représentation