Hal-Diderot
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Expériences et pratiques pédagogiques d’enseignants concernant l’utilisation d’un outil d’apprentissage numérique multilingue proposant du contenu STIM
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Monotonic crack propagation in a notched polymer matrix composite reinforced with continuous fiber and printed by material extrusion
No full textInternational audienceThe study presents the crack mouth opening and propagation of cracks in a composite material printed by material extrusion subjected to monotonic loading. The composite material is made out of a nylon matrix (with embedded short carbon fiber-called Onyx ®) and reinforced with continuous Kevlar fibers. Threepoint bending tests were performed on notched specimens built according to ASTM-E399. Tests were digitally recorded to extract crack opening displacement (COD) and crack length data through image treatment techniques (using ImageJ), and results were analyzed using linear elastic fracture mechanics parameters through the use of COD. Therefore, the crack mouth opening was established, and fracture toughness was found to be 46MPam. Additionally, microscopy analysis identified fracture zones, crack initiation, transition, and final rupture. The observed failure mechanisms were matrix cracking, fiber pull-out, fiber breakage, and defects such as non-proper fiber-matrix bonding
Numerical simulations of confined Brownian-yet-non-Gaussian motion
No full textInternational audienceBrownian motion is a central scientific paradigm. Recently, due to increasing efforts and interests towards miniaturization and small-scale physics or biology, the effects of confinement on such a motion have become a key topic of investigation. Essentially, when confined near a wall, a particle moves much slower than in the bulk due to friction at the boundaries. The mobility is therefore locally hindered and space-dependent, which in turn leads to the apparition of so-called multiplicative noises, and associated non-Gaussianities which remain difficult to resolve at all times. Here, we exploit simple, optimized and efficient numerical simulations to address Brownian motion in confinement in a broadrange and quantitative way. To do so, we integrate the overdamped Langevin equation governing the thermal dynamics of a negatively-buoyant single spherical colloid within a viscous fluid confined by two rigid walls, including surface charges. From the produced large set of long random trajectories, we perform a complete statistical analysis and extract all the key quantities, such as the probability distributions in displacements and their main moments. In particular, we propose a novel method to compute high-order cumulants by reducing convergence problems, and employ it to efficiently characterize the inherent non-Gaussianity of the confined process
The Fission Yeast Mating-Type Switching Motto: “One-for-Two” and “Two-for-One”
No full textSchizosaccharomyces pombe is an ascomycete fungus that divides by medial fission; it is thus commonly referred to as fission yeast, as opposed to the distantly related budding yeast Saccharomyces cerevisiae. The reproductive lifestyle of S. pombe relies on an efficient genetic sex determination system generating a 1:1 sex ratio and using alternating haploid/diploid phases in response to environmental conditions. In this review, we address how one haploid cell manages to generate two sister cells with opposite mating types, a prerequisite to conjugation and meiosis. This mating-type switching process depends on two highly efficient consecutive asymmetric cell divisions that rely on DNA replication, repair, and recombination as well as the structure and components of heterochromatin. We pay special attention to the intimate interplay between the genetic and epigenetic partners involved in this process to underscore the importance of basic research and its profound implication for a better understanding of chromatin biology
L'incertitude et les contrats du droit d'auteur
No full textInternational audienceI – L’incertitude, saisie par le droit des contrats du droit d’auteur. A - « à la voix active », elle intervient dans la définition du contrat.B - « à la voix passive », elle est atténuée par le contrat.II – L’incertitude, suscitée par le droit des contrats du droit d’auteur.A … par la qualité de rédaction des textes.B … par l’articulation des textes
Créativité pédagogique dans les classes ordinaires- France-Luxembourg-Québec
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Les microcosmes narratifs dans la littérature jeunesse et Young Adult en tant qu’expansion de l’horizon narratif. Une approche narratologique de la saga Harry Potter de J. K Rowling et d’autres best-sellers Young Adult du xxie siècle
No full textInternational audienceJ. K. Rowling’s Harry Potter heptalogy (1997–2007), which spans over more than four thousandpages, offers a wide array of narratological mechanisms and phenomena and, as such, constitutesa unique narrative object for the study of storytelling. Its interest also lies in its hybridity, as theseries hovers between children’s literature and Young Adult literature. In this article, I give voiceto the knowledge and know-how of published writers of fiction, sometimes departing fromliterary theory to enter the realm of creative writing theory in an interdisciplinary manner. Myaim is to look at the story from the perspective of the creative mind, operating under theprinciple that, beyond symbolism, stylistics and literary effects, the mechanics of storytelling inmiddle-grade and young adult fiction have a lot to offer us, as researchers, and our studentsendeavouring to further their understanding of language and literature.Through a hands‑on narratological analysis, I argue for the intrinsic storytelling value ofRowling’s series through the scope of narratology, focusing on coherence within imaginarynarrative worlds, and I investigate the idea of microcosms, which not only generate the conflictthat constitutes part of the reader’s conscious or unconscious horizon of expectations but alsoshapes the ever-expanding geographical horizon which takes both characters and readers intodifferent spheres of the narrative world the author has weaved
Thermophotovoltaic conversion of heat stored at ultra-high temperature
No full textInvited seminar at IUSTI (Institut Universitaire des Systèmes Thermiques Industriels), Marseille, France, April 13th 2023. Speaker: Rodolphe Vaillon.Based on the photovoltaic effect to produce electricity, thermophotovoltaics (TPV) is quite similar to solar photovoltaics (PV), but with some notable differences. While the latter technology is well established, the development of the former faces specific challenges, but has recently benefited from strong advances and new opportunities. This new momentum is linked to the development of solar-to-heat-to-power (usually called Solar TPV) converters and more recently of power-to-heat-to-power converters. In both cases, a key point is that energy can be efficiently stored under the form of heat, thus allowing to alleviate the intermittency of solar and wind power generation. The storage of latent or sensible heat at ultra-high temperature (1000 to 2400 °C), at high density and low cost [1], is the backbone of the advent of the so-called TPV "batteries" [2] (see e.g. the example of Fig. 1). To start with, the presentation will provide the basic principles of thermophotovoltaics [3, 4]. The differences of TPV conversion with respect to solar PV conversion (Fig. 2) will be described, by highlighting some advantages (tuning of the spectrum of the thermal radiation emitter, photon recycling toward the emitter, increased power density) and some drawbacks (primary energy conversion and heat losses). Then the most promising applications envisioned as part of the transition to carbon-free renewable electricity generation will be introduced. It will be explained how the concomitant development of low-cost thermal energy storage [1] and highly-efficient (> 40%) thermophotovoltaic cells [5] is currently accelerating research on power-to-heat-to-power and solar-to-heat-to-power TPV batteries. Then, an analysis of the state-of-the-art of TPV devices developed and characterized in a laboratory-setting will be proposed. It will be shown that there is a relation between optimum operating temperature of the thermal radiation emitter and bandgap of the photovoltaic cell. The presentation will conclude with a short introduction to advanced concepts, research pathways and associated challenges, and networking initiatives [6] to continue to advance the field.[1] A. Datas, Ultra high temperature thermal energy storage for dispatchable power generation, Encyclopedia of Energy Storage 2, 141-150, 2022.[2] A. Datas et al., Latent heat thermophotovoltaic batteries, Joule 6, 418-443, 2022.[3] T. Burger et al., Present efficiencies and future opportunities in thermophotovoltaics, Joule 4, 1660-1680, 2020.[4] A. Datas & R. Vaillon, Thermophotovoltaic energy conversion, Chapter 11 in: Ultra-High Temperature Thermal Energy Storage, Transfer and Conversion, Woodhead Publishing, 285-308, 2021.[5] A. LaPotin et al., Thermophotovoltaic efficiency of 40%, Nature 604.7905, 287-291, 2022.[6] Team-project TREE: https://tree.ies.umontpellier.fr; iTPV network: https://itpv.ies.umontpellier.fr. Last access on 03/22/2023
