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Holocene paleoenvironmental reconstructions in western Brittany Bay of Brest: Part I – Understanding the spatial distribution of palynological records
No full textInternational audienceThe Bay of Brest (BB) is a shallow estuarine environment in NW France. This semi-enclosed basin of 180 km² is subject to multiple hydrodynamic factors including the dual influence of oceanic currents and fluvial discharges (Aulne and Elorn main rivers) and resulting in complex hydro-climatic and hydro-sedimentary processes. This study investigates with palynological data (continental: pollen grains and marine: dinoflagellate cysts) two kinds of different materials: (i) modern surface sediments collected over the whole BB as well as (ii) three new BB sediment cores (core ‘F’ from the mouth of the Aulne river and cores PALM-KS05 and PALM-KS06 from the Brest harbour). While modern data are analysed from a statistical point of view to highlight the influence of hydrodynamic forcing on the modern distribution of palynomorphs, the cores allow for spatial comparisons of palynological data on three windows over the Early (~9.5 and ~8.5 ka BP), Middle (~4.4–4.3 ka BP interval) and Late (~1–0.9 ka BP interval) Holocene. For each time intervals, two cores located along a transect from west (more pronounced oceanic influence) to east (more intense fluvial influence from the Aulne river) are compared, located on either side of a limit that we referred to as the river-induced palynological signal (RIPS) limit. These different comparisons reveal a high degree of spatial homogeneity in BB pollen records over time, with exceptions for environments east of the RIPS limit, for which rainfall-induced fluvial discharges have a stronger impact especially considering riparian taxa (i.e. Alnus). This is intended to improve understanding of the palynological signals recorded at different BB coring sites, a first step of crucial relevance before the establishment of a palynological stack covering the Holocene from several cores collected in different shallow bays of the BB (see Valero et al., submitted – PART II)
La correspondance de Pierre Paris (1859-1931) : état des lieux d’une enquête
No full textInternational audienceLa thèse que nous avons soutenue en novembre 2021, et dont la publication est en cours, a consisté en une biographie intellectuelle de l’archéologue et historien de l’art Pierre Paris. Nos recherches nous ont notamment permis de rassembler un certain nombre de documents épistolaires, un choix de 1082 lettres écrites entre 1876 et 1931. Pour l’essentiel, il s’agit des lambeaux de la correspondance active de Pierre Paris dont nous proposons une édition critique dans le volume 3 de notre thèse. C’est aux caractéristiques de ce corpus, lequel ne sera pas publié dans le livre que nous préparons, que nous consacrerons cet article. Nous nous efforcerons de souligner sa richesse et ses limites, tout en montrant qu’il serait souhaitable, à moyen terme, de le rendre accessible grâce à une publication en ligne
Analysis of microcracking processes in microconcrete under confined compression utilising synchrotron-based ultra-high speed X-ray phase contrast imaging
No full textInternational audienceIn the present study, microconcrete (MC) samples were exposed to dynamic quasioedometric compression (QOC) tests and visualised in-situ by the means of MHz synchrotron X-ray phase-contrast imaging in the ESRF synchrotron in order to analyse the damage mechanisms governing the mechanical behaviour of concrete under high-strain-rate confined compression. To do so, small cylindrical samples were placed in polymeric confinement cell and dynamically compressed along their axial direction using SHPB (Split-Hopkinson Pressure Bar) set-up available in ID19 beamline in the European Synchrotron Radiation Facility (ESRF).The damage process was visualized with MHz X-ray phase-contrast imaging along with an ultra-high-speed camera operating at a recording frequency approximately 1 Mfps (million frames per second i.e., 880 ns interframe time). The axial stress and strain temporal profiles were obtained from standard Kolsky's (SHPB) data processing. In addition, data of radial stress and strain within the sample were deduced from non-linear analysis of the mechanical behaviour of the polycarbonate confining cell instrumented with a strain gauge. Finally, the onset and growth of microcracking observed from the equatorial zone of large spherical pores is correlated with deviatoric and pressure measurements showing how the pore collapse process develops during the applied mechanical loading.</p
La contribution des bâtonniers à la construction du droit de l’enfermement. Retour sur l’article 719 du CPP
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Affronter la vérité : Une vision claire grâce à une recherche éthique sur les expressions faciales
No full textInternational audienceDie Analyse von Gesichtsausdrücken bietet ein erhebliches Potenzial für das digitale Marketing, da sie ein präziseres Verständnis der emotionalen Reaktionen von Verbrauchern ermöglicht.Ihre Nutzung wirft jedoch wichtige ethische und rechtliche Fragen auf, insbesondere in Bezug auf den Schutz personenbezogener Daten und die Wahrung der Privatsphäre. Diese Studie untersucht die Möglichkeiten und Grenzen eines ethischen Einsatzes von Gesichtsausdrücken im Kontext des digitalen Marketings.Analysing facial expressions offers significant potential for digital marketing, enabling a more refined understanding of consumers' emotional reactions. However, its use raises important ethical and legal questions. Particularly concerning the protection of personal data and respect for privacy. This study explores the possibilities and limitations of the ethical use of facial expression in the context of digital marketing.L’analyse des expressions faciales offre un potentiel significatif pour le marketing numérique, permettant une compréhension plus fine des réactions émotionnelles des consommateurs.Cependant, son utilisation soulève d’importantes questions éthiques et juridiques, notamment en ce qui concerne la protection des données personnelles et le respect de la vie privée. Cette étude explore les possibilités et les limites d’un usage éthique des expressions faciales dans le contexte du marketing numérique
Des nombres de Cantor et de Dedekind aux nombres de Conway - Partie 1: Coupures, nombres réels et nombres surréels
No full textOn poursuit, dans cet exposé, la construction des nombres réels par la méthode des coupures de Dedekind. On présente ensuite la construction des nombres surréels par Conway
Locality for singular stochastic PDEs
No full textThis work deals with singular stochastic PDEs driven by non-translation invariant differential operators. We describe the renormalized equation for a very large class of spacetime dependent renormalization schemes. Our approach bypasses in particular the use of decorated trees with extended decorations
2 RU Reconfiguration des rapports aux usagers des archives. Synthèse du rapport de recherche
No full text3D Concrete Printing by Extrusion and Filament Deposition
No full textInternational audienceExtrusion/deposition 3D printing is currently the most widely studied and most widespread process in concrete additive manufacturing (Wangler et al. 2016; Mechtcherine et al. 2020). This robotized manufacturing process can be broken down into a number of stages, from the manufacture of the material to the curing of the printed object to ensure good mechanical performance. This complex process includes conveying the material to the print head, often by pumping, shaping it by extruding a filament material, then depositing it in successive layers to form a stable structure (Perrot et al. 2016, p. 201; Roussel 2018; Wolfs et al. 2018)
Numerical modeling of inter-ply slippage in Non-Crimp Fabrics at the continuum level within the Arbitrary Lagrangian Eulerian framework
No full textInternational audienceNon-Crimp Fabrics (NCF) are advanced fibrous reinforcements characterized by reduced fiber waviness, offering superior mechanical performance compared to woven or braided fabrics. However, their stitching-dependent cohesion makes them prone to inter-ply slippage, posing significant challenges in material forming simulations. While extensive research has been conducted on shear behavior and stitching effects, inter-ply slippage remains underexplored due to the computational demands of existing numerical strategies. Most models use Lagrangian approaches at various scales, micro, meso, and macro, relying on structural or solid elements to represent fibers, rovings, and plies. These methods, though insightful, suffer from high computational costs and difficulties in quantifying relative displacements between constituents. This study proposes a novel Arbitrary Lagrangian Eulerian (ALE) modeling framework for NCFs at the ply scale to overcome these limitations. The ALE approach simplifies ply–ply contact management and introduces a continuous scalar field to measure inter-ply slippage. A linear triangular ALE element is formulated and constitutes the base of the ALE model of NCF. A void-ALE extension of the ALE triangle is presented to handle material boundaries embedded in the same spatial configuration. Simulations of bias-extension test and forming on a hemisphere are addressed to demonstrate the ability of the model to capture inter-ply slippage