Scientific Publications of the University of Toulouse II Le Mirail
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Shannon-and von neumann-entropy regularizations of linear and semidefinite programs: Entropy regularization of LP and SDP
No full textInternational audienceWe consider the LP in standard form min {c T x : Ax = b; x ≥ 0} and inspired by ε-regularization in Optimal Transport, we introduce its ε-regularization "min {c T x + ε f (x) : Ax = b; x ≥ 0}" via the (convex) Boltzmann-Shannon entropy f (x) := i x i ln x i . We also provide a similar regularization for the semidefinite program "min {Tr(C • X) : A(X) = b; X 0}" but with now the so-called Von Neumann entropy, as in Quantum Optimal Transport. Importantly, both are not barriers of the LP and SDP cones respectively. We show that this problem admits an equivalent unconstrained convex problem max λ∈R m Gε(λ) for an explicit concave differentiable function Gε in dual variables λ ∈ R m . As ε goes to zero, its optimal value converges to the optimal value of the initial LP. While it resembles the log-barrier formulation of interior point algorithm for the initial LP, it has a distinguishing advantage. Namely for fixed λ, Gε(λ) is obtained as a minimization over the whole space x ∈ R d (and not over x ≥ 0) to still obtain a nonnegative solution x(λ) ≥ 0, whence an explicit form of Gε very useful for its unconstrained maximization over R m
Performance bounds for priority-based stochastic coflow scheduling
No full textWe consider the coflow scheduling problem in the non-clairvoyant setting, assuming that flow sizes are realized on-line according to given probability distributions. The goal is to minimize the weighted average completion time of coflows in expectation. We first obtain inequalities for this problem that are valid for all non-anticipative order-based rate-allocation policies and define a polyhedral relaxation of the performance space of such scheduling policies. This relaxation is used to analyze the performance of a simple priority policy in which the priority order is computed by Sincronia from expected flow sizes instead of their unknown actual values. We establish a bound on the approximation ratio of this priority policy with respect to the optimal priority policy for arbitrary probability distributions of flow sizes (with finite first and second moments). Tighter upper bounds are obtained for some specific distributions. Extensive numerical results suggest that performance of the proposed policy is much better than the upper bound.</div
Euclid Quick Data Release (Q1). The role of cosmic connectivity in shaping galaxy clusters
No full textInternational audienceThe matter distribution around galaxy clusters is distributed over several filaments, reflecting their positions as nodes in the large-scale cosmic web. The number of filaments connected to a cluster, namely its connectivity, is expected to affect the physical properties of clusters. Using the first Euclid galaxy catalogue from the Euclid Quick Release 1 (Q1), we investigate the connectivity of galaxy clusters and how it correlates with their physical and galaxy member properties. Around 220 clusters located within the three fields of Q1 (covering ), are analysed in the redshift range 0.2 < z < 0.7. Due to the photometric redshift uncertainty, we reconstruct the cosmic web skeleton, and measure cluster connectivity, in 2-D projected slices with a thickness of 170 comoving and centred on each cluster redshift, by using two different filament finder algorithms on the most massive galaxies (M_*\ > 10^{10.3} \ M_\odot). In agreement with previous measurements, we recover the mass-connectivity relation independently of the filament detection algorithm, showing that the most massive clusters are, on average, connected to a larger number of cosmic filaments, consistent with hierarchical structure formation models. Furthermore, we explore possible correlations between connectivities and two cluster properties: the fraction of early-type galaxies and the Sérsic index of galaxy members. Our result suggests that the clusters populated by early-type galaxies exhibit higher connectivity compared to clusters dominated by late-type galaxies. These preliminary investigations highlight our ability to quantify the impact of the cosmic web connectivity on cluster properties with Euclid
Le Ring à Lyon (1904): chronologie et dossier de presse des huit représentations, dezede.org, https://dezede.org/dossiers/id/798/
No full texthttps://dezede.org/dossiers/id/798
Frequency-aware Surrogate Modeling With SMT Kernels For Advanced Data Forecasting
No full textInternational audienceThis paper introduces a comprehensive open-source framework for developing correlation kernels, with a particular focus on user-defined and composition of kernels for surrogate modeling. By advancing kernel-based modeling techniques, we incorporate frequency-aware elements that effectively capture complex mechanical behaviors and timefrequency dynamics intrinsic to aircraft systems. Traditional kernel functions, often limited to exponential-based methods, are extended to include a wider range of kernels such as exponential squared sine and rational quadratic kernels, along with their respective firstand second-order derivatives. The proposed methodologies are first validated on a sinus cardinal test case and then applied to forecasting Mauna-Loa Carbon Dioxide (CO 2 ) concentrations and airline passenger traffic. All these advancements are integrated into the open-source Surrogate Modeling Toolbox (SMT 2.0), providing a versatile platform for both standard and customizable kernel configurations. Furthermore, the framework enables the combination of various kernels to leverage their unique strengths into composite models tailored to specific problems. The resulting framework offers a flexible toolset for engineers and researchers, paving the way for numerous future applications in metamodeling for complex, frequency-sensitive domains
Présentation et conclusions séminaire Humanités Numériques. Organisé par Emilie CADEZ et Cécile MARY TROJANI. De la pluma al xml-tei: edición, gestión y explotación de textos antiguos. Séance animée par Víctor Caballero Gómez (Universidad de Salamanca).
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Weak Triangle Inequality for the Lempert function
No full text9 pagesThe (unbounded version of the) Lempert function on a domain does not usually satisfy the triangle inequality, but on bounded -smooth strictly pseudoconvex domains, it satisfies a weaker version, with . We show that pseudoconvexity is necessary for this property as soon as has a -smooth boundary. We also give some estimates in some domains which are model for local situations
Secondary ion mass spectrometry (SIMS) analysis of (113) PIN & NIP diamond structures
No full textInternational audienceWith tremendous physical properties, diamond is considered to be the ultimate semiconductor for high power electronics. Indeed, diamond is awaited to endure high electric fields with low leakage current. It is then a candidate of choice for high voltage and high temperature power electronics. Even if some incursions were made on the (110) orientation, the conventional crystalline orientations used for diamond are (111) and (100). Lying in between, (113) is a stable growth orientation during chemical vapor deposition and could allow obtaining enlarged crystals. For p-type doping with boron, the LSPM lab has proven the interest of the (113) orientation by growing p-type free-standing plates with equivalent quality to (100) orientation and, very recently, enlarged (113) p+-substrates [1]. For n-type doping with phosphorus, the GEMaC lab has shown that the (113) orientation give access to lower compensation ratio than (100) with higher electron mobility [2] at temperature above 450°C. All those results pave the way for the realization (113) diamond bipolar devices. In the framework of the ANR-LAPIN113 project [3], the LAAS lab, specialized in power devices simulation and fabrication, has defined the “ideal” PIN and NIP stacks that might ensure the target breakdown voltage. LSPM and GEMaC labs were then in charge of the synthesis to get requested PIN and NIP structures. Thanks to secondary ion mass spectrometry (SIMS), we analysed the depth-distributions of dopants over each structure. The depth profiles reveal the ability of the grower labs to achieve requested PIN and NIP structures on (113) orientation. The knowledge of the exact doping profiles will allow to simulate diode characteristics and help to understand the future experimental measurements of the diodes that will be performed on the PIN and NIP structures. References1.R. Mesples-Carrère, R. Issaoui, A. Valentin, L. Banaigs, O. Brinza, F. Bénédic, J. achard. Diamond Relat. Mater. 149 (2024), 111659. https://doi.org/10.1016/j.diamond.2024.111659 2.M.-A. Pinault-Thaury, I. Stenger, R. Gillet, S. Temgoua, E. Chikoidze, Y. Dumont, F. Jomard, T. Kociniewski, J. Barjon. Carbon 175 (2021) 254. https://doi.org/10.1016/j.carbon.2021.01.011 3.For information about the ANR-LAPIN113 project see https://anr.fr/Projet-ANR-20-CE05-003
Apprendre le russe à travers les arts
No full textInternational audienceLa ressource numérique « Apprendre le russe à travers les arts » offre une manière vivante et stimulante d’explorer la langue et la culture russes à travers des supports pédagogiques variés et téléchargeables
Terres cuites et sociétés antiques
No full textLes figurines de terre cuite ont été largement diffusées dans les sociétés anciennes en raison de leurs dimensions modestes et de leur faible coût de production. Fabriquées en nombre, elles offrent une matière de première importance, tant du point de vue quantitatif qu’iconographique, pour tenter de cerner les goûts et les croyances des populations sur le temps long. Si ces objets ont longtemps été étudiés d’un point de vue strictement stylistique et iconographique, les recherches actuelles tendent à mettre en lumière leurs fonctions et leurs contextes d’utilisation. Composé de sept articles, ce dossier montre comment la statuaire de terre cuite constitue un champ d’investigation considérable, qui ouvre de nombreuses perspectives pour comprendre les sociétés antiques