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Situations de vulnérabilités en contexte plurilingue dans les espaces francophones
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Présence de la musique dans l’iconographie du Salon de la Paix à Versailles : les peintures et les trophées des bas-reliefs de métal doré
No full textInternational audiencePending the results of a systematic inventory of musical subjects in the decorations of the Palace of Versailles, an inventory currently in progress, we will focus here on a particular space in the palace, the Salon de la Paix, and on a predominant but never truly studied aspect of its decoration: the series of gilded metal bas-reliefs with instrumental trophies as their subject. We will trace the historical sources that mention them by placing them in the context in which they were born: the “Grande Galerie” or Hall of Mirrors, and the two adjacent salons, the Salon de la Guerre and the Salon de la Paix, whose pictorial program has been intensively studied for three decades. We will provide this state of the art to better note the little attention that has been paid to our subject until now. Then we will analyze the composition of these trophies, the instrumentarium represented, its musical relevance at the apotheosis of the reign of Louis XIV and its symbolism at the time when the court of Louis XIV left Paris to settle in Versailles.Dans l’attente des résultats d’un recensement systématique des sujets musicaux dans les décors du château de Versailles, recensement en cours de constitution, nous nous intéresserons ici à un espace particulier du château, le Salon de la Paix, et à un aspect prédominant mais jamais véritablement étudié de son décor : la série de bas-reliefs en métal doré ayant pour sujet des trophées instrumentaux. Nous retracerons les sources historiques qui les mentionnent en les replaçant dans le contexte qui les a vu naître : la « Grande galerie » ou Galerie des Glaces, et les deux salons qui lui sont contigus, le Salon de la Guerre et le Salon de la Paix, dont le programme pictural a été intensivement étudié depuis trois décennies. Nous donnerons cet état de l’art pour mieux constater le peu d’attention qui a été porté à notre sujet jusqu’à présent. Puis nous analyserons la composition de ces trophées, l’instrumentarium représenté, son actualité musicale à l’apothéose du règne de Louis XIV et son symbolisme au moment où la cour de Louis XIV quitte Paris pour s’installer à Versailles
Chemical bioexergy analysis in thermochemically converted biomass fuels: An introductory review
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Geometry-agnostic model reduction with GNN-generated reduced POD bases and boosted PGD enrichment for (non)linear structural elastodynamics
No full textInternational audienceThis contribution proposes a new and significantly enhanced extension of a recently-introduced hybrid Graph Neural Network (GNN)-based reduced-order modeling approach for the numerical solution of time-dependent partial differential equations on non-parametric finite element meshes. Building upon previous proof-of-concept work, this more generalized framework presents a number of key novelties: tight integration of graph-based learning with physical information via direct imposition of finite element operators as node and edge level features; introduction of a Grassmannian subspace distance measure as a dedicated training objective; incorporation of a Gated Recurrent Unit (GRU) for a more efficient and lightweight architecture; hybridization with other Galerkin-based reduced-order methods such as the Proper Orthogonal Decomposition (POD); and a first treatment of nonlinear problems. A novel, on-the-fly enrichment mechanism, modified from a classical Proper General Decomposition (PGD) and dubbed "Boosted PGD", is additionally introduced to improve prediction accuracy at low computational cost via additional greedy corrective modes. The efficacy of the overall methodology is assessed on two challenging datasets featuring significant geometric and topological variations that include highly heterogeneous spatial discretizations. A variety of performance studies demonstrate very competitive accuracy and computational cost in simulating highly-dynamic behavior when compared to conventional fullorder finite element models, including a remarkable capacity to generalize to configurations well outside of the topological scope of the original training and validation sets. Results imply that solvers constructed from such an approach may enable more scalable and robust mechanical simulations for complex, real-world engineering applications related to iterative design
15N NMR study of protonation position determination in 2-(6-methoxynaphthalen-2-yl)vinyl diazine chromophores
No full textInternational audienceThe 1H-15N HMBC spectra were successfully used for protonation position determination in 4-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyrimidine (1), 2-[(E)-2-(6-methoxynaphthalen-2-yl)-vinyl]quinoxaline (2), 2-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyrazine (3), and 3-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyridazine (4). Mono protonation was proved. In three cases (compounds 1, 2 and 4) only one nitrogen was protonated while in pyrazine compound 3 the equilibrium between regioisomers was observed
Using thin AZO layers coupled with SiNx:H as a way to decrease Indium consumption in SHJ cells and modules
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Discrete numerical analysis of cohesive granular flow in a thin rotating drum: Flow regimes and cohesion estimation
No full textInternational audienceIn this study, we investigate the rheological behavior of cohesive granular flows within a rotating drum geometry using discrete element method (DEM) simulations. By systematically varying particle size, cohesion, and stiffness, we identify the emergence of distinct flow regimes-consistent with prior experimental observations. While the transitions between these regimes are primarily governed by cohesion, particle stiffness is also shown to significantly influence flow dynamics.To interpret the numerical results, we employ a dimensional analysis rooted in the physics of adhesive particle collisions. This analysis provides a conceptual framework for the remainder of the paper, which explores how "upscaled" discrete simulations can replicate experimental findings and help infer interparticle contact properties such as the adhesive surface energy. Notably, we use it to examine rotating drum experiments involving a unique class of granular materials, ice powders, which holds particular relevance in planetary science applications, and which flowability was shown to be strongly temperature-dependent
Pressure effects on soot formation in turbulent CH4 flames in an O2/CO2 atmosphere
No full textInternational audienceThis study investigates the effect of pressure on soot formation in turbulent oxy-fuel methane jet flames using Planar Laser-Induced Incandescence (PLII) calibrated using Light Extinction Measurements (LEM). The bulk jet velocity was held constant while the pressure was increased from 1 bar (Re = 3500) to 3 bar (Re = 10,600) and 5 bar (Re = 17,700) inside our new high-pressure vessel. DSLR imaging revealed increased flame luminosity and reduced flame length with rising pressure, consistent with previous literature. Planar soot volume fraction (SVF) measurements showed a significant increase in soot levels with pressure, with the maximum mean SVF increasing by factors of 7 and 14 at 3 bar and 5 bar, respectively. The intermittency analysis indicated a more continuous soot field at elevated pressures, while the Probability Density Function (PDF) analysis demonstrated a shift toward higher soot concentrations with reduced variability. Radially and volumetrically integrated SVF further confirmed a pressure dependence, with total soot loading (volume-integrated SVF) showing a P 2.1 pressure dependence. However, when normalized by the fuel mass flow rate, this dependence weakens to show almost linear behavior, suggesting that both pressure and additional carbon input contribute to the observed trends. These findings provide new insights into the pressure-driven mechanisms governing soot formation in high-pressure turbulent oxy-fuel flames and provide dataset for validating numerical models
Parameter influence analysis in a 3D TBM model via sensitivity analysis and GP metamodels
No full textInternational audienceUrban tunnel excavation with tunnel boring machines induces ground movements that can affect nearby structures. Three-dimensional finite element models (FEM) are widely used to predict these settlements, but their high computational cost limits direct exploration of parameter influence. This work presents a 3D FEM simulator of mechanized tunneling and a methodology to quantify the impact of both numerical and physical inputs on settlement predictions. First, an accuracy-cost model reduction study evaluates the effect of domain dimensions and mesh densities on a small number of scalar quantities of interest extracted from simulated settlement fields. Empirical error models are fitted and used to select a reduced configuration that balances accuracy and runtime. Second, Gaussian process models are trained on simulation data from the reduced configuration and validated using exact leave-one-out cross-validation. These metamodels enable the computation of Sobol’ sensitivity indices with quantified uncertainty, identifying the most influential geological, operational, and loading parameters. The proposed framework reduces the cost of sensitivity analysis for computationally intensive 3D tunneling simulations, supporting input screening and dimensionality reduction for design and calibration
More powerful energetic reasoning for the cumulative scheduling problem
No full textInternational audienceEnergetic reasoning is an efficient filtering technique for the Cumulative SchedulingProblem. In this paper we propose a new definition of the energy balance of intervals,together with a new checker that is more accurate for each interval. Our approachinvolves solving a tripartition problem. For checking the intervals, we also propose acubic algorithm leveraging our approach. We report computational results that confirmthat it is more efficient than the classical approaches