HAL-INSA Toulouse
Not a member yet
34325 research outputs found
Sort by
Gradient-enhanced global sensitivity analysis with Poincaré chaos expansions
No full textChaos expansions are widely used in global sensitivity analysis (GSA), as they leverage orthogonal bases of L2 spaces to efficiently compute Sobol' indices, particularly in data-scarce settings. When derivatives are available, we argue that a desirable property is for the derivatives of the basis functions to also form an orthogonal basis. We demonstrate that the only basis satisfying this property is the one associated with weighted Poincaré inequalities and Sturm-Liouville eigenvalue problems, which we refer to as the Poincaré basis. We then introduce a comprehensive framework for gradient-enhanced GSA that integrates recent advances in sparse, gradient-enhanced regression for surrogate modeling with the construction of weighting schemes for derivative-based sensitivity analysis. The proposed methodology is applicable to a broad class of probability measures and supports various choices of weights. We illustrate the effectiveness of the approach on a challenging flood modeling case study, where Sobol' indices are accurately estimated using limited data
Adherence assessment under fatigue loading using the three-point bending test
No full textInternational audienc
A Multi-agent System Approach for Dynamic and Adaptive Daily Profile Detection in Building Data
No full textInternational audienc
Sum rules via large deviations: polynomial potentials and multi-cut regime on the unit circle
No full textSum rules are elegant formulas that relate entropy functionals to coefficients associated with orthogonal polynomials [Sim11]. In a series of paper (see for example]), interesting connections have been established between the large theory of spectral measures built on random matrices and sum rules. In this work, we extend this approach by studying sum rules within random matrix models with polynomial potentials on the unit circle, with a particular focus on cases where the equilibrium measure lacks full support.</div
Proportional modulation of proliferation and motility under 2D compressive stress depends on mesenchymal phenotype
No full textInternational audienceMechanical stresses, including compression, arise during cancer progression. In solid cancer, especially breast and pancreatic cancers, the rapid tumor growth and the environment remodeling explain their high intensity of compressive forces. However, the sensitivity of compressed cells to targeted therapies remains poorly known. In breast and pancreatic cancer cells, pharmacological PI3K inactivation decreased cell number and induced apoptosis. These effects were accentuated when we applied 2D compression forces in mechanically responsive cells. Compression selectively induced the overexpression of PI3K isoforms and PI3K/AKT pathway activation. Furthermore, transcriptional effects of PI3K inhibition and compression converged to control the expression of an autophagy regulator, GABARAP, whose level was inversely associated with PI3K inhibitor sensitivity under compression. Compression alone blocked autophagy flux in all tested cells, whereas inactivation of basal PI3K activity restored autophagy flux only in mechanically non-responsive compressed cells. This study provides direct evidence for the role of the PI3K/AKT pathway in compression-induced mechanotransduction. PI3K inhibition promotes apoptosis or autophagy, explaining PI3K importance to control cancer cell survival under compression
Section 06 Sciences de l’information : fondements de l’informatique, calculs, algorithmes, représentations, exploitations: Rapport de conjoncture 2024
No full textLa section 6 du Comité national de la recherche scientifique est, avec la section 7, une des deux sections traitant de la science informatique, et plus précisément de l’algorithmique et de la combinatoire, du calcul, du logiciel, de la sécurité, des réseaux et systèmes distribuées, des données et connaissances, de l’intelligence artificielle et de l’aide à la décision, ainsi que de la bio-informatique et de l’informatique quantique. Ce rapport présente le périmètre thématique de la section, discute de la place des femmes ainsi que des évolutions récentes des pratiques de recherche, présente la conjoncture des différents thèmes de recherche et enfin décrit les carrières au CNRS des chercheurs et chercheuses de la section
Optimal Motion Prediction for Human-to-Robot Handovers
No full textSeamless human-robot handovers require precision, timing, and safety. In the absence of visual feedback for humans, robots rely on accurately estimating and predicting their motion. In this work, a real-time human motion prediction and estimation framework for human-to-robot handovers relying on a planar biomechanical model and cost functions extracted from the motor control literature is proposed. Thanks to inverse reinforcement learning, it is possible to iteratively determine the optimal weighting of these cost functions by solving a direct optimal control problem for reaching tasks. An affordable, markerless human pose estimation pipeline was used to estimate in real-time and predict the human arm motion. These predictions were then integrated into a model predictive controller for a seven-degree-of-freedom robot manipulator, successfully intercepting participants' hands in 88.6 ± 8.0% of trials, 0.63s before they reached their intended final hand pose. Experimental validation with blindfolded participants resulted in a predicted joint angle error of 8.7±4.6deg during handover trials. The proposed framework offers a promising solution for safe and effective human-to-robot handovers, particularly for applications involving visually impaired users
Comparison of modular multilevel and flying capacitor converters made of wide bandgap switches for new MVDC grids
No full textInternational audienceA detailed and comparative analysis of modular multilevel and flying capacitor converters (MMC and, FCC resp.) is proposed in the context of new functionalities developments for new medium-voltage DC (MVDC) grids, taking advantage of the performance and improvement perspectives offered by wide-bandgap (WBG) components. The novelties of this work lies in the generic formalism developed, which enables both structures to be compared on an equal basis, as well as facilitating access to a number of characteristics. This comparison is generalized to the number of phases, number and type of cells, and modulation index. This approach provides a clear overall understanding of the benefits and drawbacks of the two structures in terms of structure sophistication, power conversion capabilities, control complexity and operating mode freedom. The study highlights the flexibility and the greater power range of the MMC, despite being more complex to control and bulkier than the FCC
High temperature evolution of interfacial metal film bonding two 4H-SiC substrates
No full textInternational audienceThe high temperature behavior of thin metal films (tungsten and titanium) confined between two off-axis single crystal SiC substrates is investigated. Through the application of transmission and scanning transmission electron microscopy, scanning electron microscopy, and X-ray scattering techniques, we examine the phase and morphology changes induced by high temperature annealing in thin layers consisting of these materials, as well as at their interfaces with SiC. Upon high-temperature annealing, a uniform and continuous W film formed by low-temperature deposition undergoes a transition to an array of discontinuous domains surrounded by a direct SiC/SiC interface. In contrast, a Ti film remains continuous with a strong thickness alteration. In parallel to stepbunching process of the internal SiC surfaces, both materials transform into new crystalline phases which contain Si and/or C atoms and achieve an epitaxial relationship with the SiC structures. The experimental findings are discussed in terms of dewetting phenomena and analyzed in light of potential chemical and structural reactions that may occur during interface reconstructions.</div
Lipschitz Stability of an Inverse Problem of Transmission Waves with Variable Jumps
No full textInternational audienceThis article studies an inverse problem for a transmission wave equation, a system where the main coefficient has a variable jump across an internal interface given by the boundary between two subdomains. The main result obtains Lipschitz stability in recovering a zeroth-order coefficient in the equation. The proof is based on the Bukhgeim-Klibanov method and uses a new one-parameter global Carleman inequality, specifically constructed for the case of a variable main coefficient which is discontinuous across a strictly convex interface. In particular, our hypothesis allows the main coefficient to vary smoothly within each subdomain up to the interface, thereby extending the preceding literature on the subject