HAL Université de Toulouse, et Toulouse INP
Not a member yet
159308 research outputs found
Sort by
Learning 3-Manifold Triangulations
No full textInternational audienceReal 3-manifold triangulations can be uniquely represented by isomorphism signatures. Databases of these isomorphism signatures are generated for a variety of 3-manifolds and knot complements, using SnapPy and Regina, then these language-like inputs are used to train various machine learning architectures to differentiate the manifolds, as well as their Dehn surgeries, via their triangulations. Gradient saliency analysis then extracts key parts of this language-like encoding scheme from the trained models. The isomorphism signature databases are taken from the 3-manifolds' Pachner graphs, which are also generated in bulk for some selected manifolds of focus and for the subset of the SnapPy orientable cusped census with initial tetrahedra. These Pachner graphs are further analysed through the lens of network science to identify new structure in the triangulation representation; in particular for the hyperbolic case, a relation between the length of the shortest geodesic (systole) and the size of the Pachner graph's ball is observed
A bilevel optimal control method and application to the hybrid electric vehicle
No full textInternational audienceIn this article we present a new numerical method based on a bilevel decomposition of optimal control problems. A strong connection between the proposed method and the classical indirect multiple shooting method is shown in the regular case, thanks to a link between the Bellman’s value function and the costate from the Pontryagin maximum principle. The value functions are needed in our bilevel decomposition but they are generally difficult to compute. We approximate them by neural networks that have a high potential of generalization and that provide an efficient computation of the gradient of the cost function. We apply the proposed method to an industrial problem, consisting of the determination of torque split and gear shift of a hybrid electric vehicle, the objective being the minimization of the fuel consumption on a given representative cycle. Numerical methods and results are discussed, as well as the possible improvements of the proposed approach
Waveform Modelling for the Laser Interferometer Space Antenna
No full textInternational audienceLISA, the Laser Interferometer Space Antenna, will usher in a new era in gravitational-wave astronomy. As the first anticipated space-based gravitational-wave detector, it will expand our view to the millihertz gravitational-wave sky, where a spectacular variety of interesting new sources abound: from millions of ultra-compact binaries in our Galaxy, to mergers of massive black holes at cosmological distances; from the beginnings of inspirals that will venture into the ground-based detectors' view to the death spiral of compact objects into massive black holes, and many sources in between. Central to realising LISA's discovery potential are waveform models, the theoretical and phenomenological predictions of the pattern of gravitational waves that these sources emit. This white paper is presented on behalf of the Waveform Working Group for the LISA Consortium. It provides a review of the current state of waveform models for LISA sources, and describes the significant challenges that must yet be overcome
Développement et optimisation de filaments lin/PLA pour l'impression 3D de biocomposites à fibres continues
No full textInternational audienceL'impression 3D est une technologie intéressante et prometteuse pour fabriquer des composites renforcés par des fibres naturelles. Cependant, l’impression de composites à fibres longues est souvent limitée aux composites à fibres synthétiques (Carbone, Kevlar). Malgré les études récentes, la qualité des pièces réalisées par impression 3D de composites renforcés par des fibres longues végétales est souvent modeste. En effet, les diamètres des fils torsadés utilisables limitent les performances et l’imprégnation des pièces élaborées. Dans le cadre du projet ANR FLOEME, des fils spécifiques de lin/PLA commélés et guipés ont été élaborés. Ce travail se propose d’étudier le potentiel de ce fils en tant que filaments pour l’impression de composite à fibres longue et continue. Un traitement de consolidation a été mis au point pour faciliter l'impression des composites. Les observations microscopiques ont montré que le processus de consolidation assure l'imprégnation des fibres de lin par le polymère, ce qui le rend efficace pour l'impression de composites avec de longues fibres. De même, les tests de traction ont révélé que le module de Young augmente après la consolidation des filaments
Resource acquisition and allocation trade-offs and the link to genetic correlation between traits in agriculture
No full textDisentangling conduction pathways at the ionic–electronic interface in EMI-TFSI-covered graphene transistors
No full textInternational audienceTransport of electrons and ions at carbon surfaces immersed in electrolytes is instrumental for a wide variety of membrane processes as well as energy storage in batteries and supercapacitors. Ion transport in a nanoporous electrode strongly depends on its electronic conductance and on the interfacial capacitance with the electrolyte. In this study, we use in-plane impedance spectroscopy to disentangle in-plane ionic and electronic transport on a single crystal graphene transistor covered by an ionic liquid droplet (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMI-TFSI). droplet. Due to the atomic thickness of graphene combined to the strong affinity of EMI+ for carbon, this transistor maximizes ion–electron couplings. Using gate- and temperature-dependent in-plane spectroscopy, we extract both the electronic and ionic conductance of the transistor on a wide range of charge carrier density and over several decades of electrolyte conductivity. We show that despite an exceptionally high capacitive coupling at the carbon–EMI-TFSI interface, the ionic and electronic transport pathways are decoupled at the micrometric scale, in agreement with predicted lengthscales involved in the electronic-ionic interfacial transport
Tellurium-Terminated MXene Synthesis via One-Step Tellurium Etching
No full textInternational audienceAbstract With the rapid development of two-dimensional MXene materials, numerous preparation strategies have been proposed to enhance synthesis efficiency, mitigate environmental impact, and enable scalability for large-scale production. The compound etching approach, which relies on cationic oxidation of the A element of MAX phase precursors while anions typically adsorb onto MXene surfaces as functional groups, remains the main prevalent strategy. By contrast, synthesis methodologies utilizing elemental etching agents have been rarely reported. Here, we report a new elemental tellurium (Te)-based etching strategy for the preparation of MXene materials with tunable surface chemistry. By selectively removing the A-site element in MAX phases using Te, our approach avoids the use of toxic fluoride reagents and achieves tellurium-terminated surface groups that significantly enhance sodium storage performance. Experimental results show that Te-etched MXene delivers substantially higher capacities (exceeding 50% improvement over conventionally etched MXene) with superior rate capability, retaining high capacity at large current densities and demonstrating over 90% capacity retention after 1000 cycles. This innovative synthetic strategy provides new insight into controllable MXene preparation and performance optimization, while the as-obtained materials hold promises for high-performance sodium-ion batteries and other energy storage systems
Wide Electrical Tunability of the Valley Splitting in a Doubly Gated Silicon-on-Insulator Quantum Well
No full textInternational audienc
Flicker Visibility and Irritability Threshold Measurements
No full textInternational audienceThe IEC flicker observer model, or light flickermeter, is an algorithm whose purpose is to assess the severity of flicker produced by artificial lighting. Historically, it was developed by extraction from the voltage flickermeter, and it is thus based on experiments with incandescent lamps. This paper is one in a series of papers focused on verifying the light flickermeter performance for LED light sources. Flicker perceptibility (visibility) and irritability thresholds are measured in conditions taking into account peripheral vision. A new flicker irritability threshold measurement procedure is presented. The data are then compared to the thresholds indicated by the light flickermeter. The paper presents a detailed and complete verification of the flickermeter thresholds both in terms of the flicker severity measure (Pst) as well instantaneous flicker (Pinst) and brings a comprehensive understanding of what these two quantities actually represent
Linguistique coréenne et japonaise : dynamiques contrastives. Introduction
No full textInternational audienceThe Korean and Japanese languages, although typologically, geographically, and culturally close, are still too rarely contrasted or compared. This volume aims to help fill this gap. To that end, it brings together seventeen articles that reflect the current state of Francophone research on issues of contrastive or comparative linguistics based on one of these two languages; that address broader linguistic questions from Korean or Japanese perspectives; or that provide an in-depth analysis of specific linguistic features in one of the two languages. The volume includes works by linguists from diverse theoretical backgrounds, research domains, and generations. As the title of this collection indicates, the target languages are Korean and Japanese, but the contributions are not limited to these two: readers will also find articles that draw on Chinese, Spanish, English, and, of course, French, as well as another Japonic variety—the Hachijō language.Les langues coréenne et japonaise, bien que typologiquement, géographiquement, et culturellement proches sont encore trop rarement contrastées ou comparées. Ce volume souhaite contribuer à combler cette lacune. A cet effet, il rassemble 17 articles qui reflètent l’état de la recherche francophone actuelle sur des questions delinguistique contrastive ou comparative à partir de l’une de ces deux langues, qui abordent des questions linguistiques plus générales à partir des perspectives coréenne ou japonaise, ou bien, enfin, qui traitent en profondeur tel ou tel point de linguistique de l’une des deux langues. On y lira des travaux de linguistes de tous horizons théoriques, de tous domaines, et de toutes générations. Comme le titre du présent volume l’indique, les langues cibles sont le coréen et le japonais, mais les contributions ne se limitent pas à ces dernières, puisqu’on trouvera des articles qui convoquent le chinois, l’espagnol, l’anglais, en plus, bien évidemment, du français, ainsi qu’une autre variété japonique, la langue de Hachijō