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Experimental study of thermocline behavior under high propagation velocities in a water based thermal energy storage
No full textInternational audienceThis experimental study investigates the development of the thermocline under varied operating conditions and particularly at high propagation velocities ranging from 0.5 mm.s -1 up to 8 mm.s -1 and temperature differences (ΔT) of 10 • C, 30 • C and 65 • C. For this purpose, a new experimental setup, designed to investigate thermocline formation, propagation, and withdrawal is implemented. The setup meets essential requirements for acquiring controlled validation data for CFD models and enables the collection of novel high-velocity flow data. The storage system features extensive instrumentation, including temperature measurements at curved tank bottoms and radial positions. Dynamic experiments validated literature findings, demonstrating stronger stratification with slower axial propagation velocities and larger temperature differences. High propagation velocities remain feasible with adequate ΔT, i.e. with a Richardson number based on the penetration height of the inlet fluid, Ri 0,hi ≥ 0.25 ensuring a thin thermocline for this test section. Variation of the extraction distribution system revealed the influence of fluid withdrawal on thermocline thickness, underscoring the need to consider outlet dynamics in distributor design. These findings establish the relevance of Ri 0,hi for predictive performance correlations and provide a foundation for optimizing thermal energy storage systems through refined distributor designs. Finally, an original definition of thermocline thickness was introduced, based on the slope of the thermocline, offering an alternative to the classical boundary-temperature approach and limiting the dependence on temperature limits
Beyond the <i>déjà-vu</i>: Intermedial tranpositions of the <i>film noir</i> motif of the automobile in contemporary Anglo-American and French novel
No full textInternational audienceThis article focuses on the stakes of the intermedial transpositions of the filmic motif of the automobile from the noir genre in a corpus of four Anglo-American novels which bear the imprint of cinema: Jean Echenoz's Cherokee (1983), Tanguy Viel's L'Absolue Perfection du Crime (2001), Martin Amis's London Fields (1989), Robert Coover's Noir (2010). Automobile and automobility will be considered as “semantic/syntactic” criteria defining the noir genre (Rick Altman). The transposition of this filmic motif and of genre scenes such as the car chase contribute to the “return to narrative” (Dominique Viart) after the relative decline of narrative fiction in the previous decades, under the influence of the Nouveau Roman in France and of formalist experimentations in the United States and the United Kingdom. It contributes to the renewal of the contemporary novel from in a critical light, denouncing traditional novelistic conventions and genre stereotypes
Fluorine as a key element in solid-state chemistry of mixed anions 3d transition metal-based materials for electronic properties and energy
No full text"ADC - Accord Couperin / American Chemical Society (2024-2026)"International audienceMixed anion compounds containing fluorine and based on 3d transition elements represent a class of materials with significant interest in solid-state chemistry. Indeed, their highly varied chemical composition, structural diversity, and the resulting electronic properties provide a rich playground for imagining new applications in the field of energy. The anions and the chemical bonds they form with the 3d transition elements are at the heart of this review. Key parameters such as electronegativity, hardness, and polarizability are introduced and discussed to better understand the charge capacity of the anion and the bonds formed in the solid. Oxyfluorides represent the most studied family due to the size similarity of the two anions, and part of the review is dedicated to the specific synthesis of these materials by systematically adjusting the fluorine content within various structures and analyzing the electronic and electrochemical properties of these compositions. The final sections focus on materials with structures often exhibiting a two-dimensional character, where ionic blocks coexist with covalent layers, such as fluorochalcogenides, fluoropnictides, and fluorotetrelides. The compositions and structures are systematically correlated with the electronic properties
La naissance du vocabulaire botanique en ancien français
No full textInternational audienceThis article examines the emergence of botanical vocabulary in French during the 13th c. It is based on the Livre des simples médecines (ed. P. Dorveaux) and a translation of the Libellus de simplicibus medicinis (ed. T. Hunt). The first attestations and changes in plant names are analysed and it is demonstrated that the texts distinguish between varieties, establish categories (arbre, buisson, herbe: “tree, bush, herb”) and provide descriptive elements that allow the beginnings of a definition.Dans cet article est étudiée la naissance du vocabulaire botanique en français au XIIIe siècle, à partir du "Livre des simples médecines" (éd. P. Dorveaux) et d’une traduction du "Libellus de simplicibus medicinis" (éd. T. Hunt). On analyse les premières attestations et évolutions des noms des plantes et on s’attache à montrer que les textes distinguent des variétés, mettent en place des catégories (arbre, buisson, herbe) et fournissent des éléments descriptifs qui permettent une amorce de définition
s12y : Développement d'applications durables
No full textInternational audienceLes applications logicielles ont envahi notre vie. Elles sont utilisées pour des actes banals (manger au restaurant universitaire avec IZLY), des démarches administratives (déclarer et payer ses impôts), du réseautage (LinkedIn, Instagram), et bien plus encore. On les trouve sous toutes les formes : web, mobile, desktop, etc. Cette prolifération logicielle implique un déluge d'énergie disponible et une quantité massive de matériel pour la faire fonctionner. Cela pose des questions de soutenabilité : peut-on continuer ainsi longtemps dans un monde fini ? Sans adopter l'approche radicale de « décroissance logicielle » (produire moins d'applications, réapprendre à s'en passer, fabriquer des applications basse technologie), une autre piste est d'intégrer la durabilité (ou « Sustainability », abrégé en « s12y ») dans le logiciel que l'on souhaite construire, comme on le fait déjà pour d'autres attributs de qualité. Cet article court vulgarise les travaux réalisés pour concrétiser le s12y lors du développement d'applications mobiles Android et iOS, et dont l'esprit peut tout à fait être généralisé à d'autres typologies d'applications logicielles
Understanding and Influencing End-User Behavior in Software Energy Consumption
No full textInternational audienceWith growing concerns about computing’s environmental impact, sustainable IT practices must engage all stakeholders—including end-users. This study investigates how user behavior influences software energy consumption through a mixed-methods approach: a campus survey (N=280) revealed that while 91.5% understand device energy use, only 55.3% recognize software’s role, and just 46.8% modify habits despite 79.3% acknowledging individual responsibility. Follow-up interviews highlighted demographic divides, witholder (25-64) and advanced-degree users showing greater awareness. A week-long field experiment at an IT company demonstrates that real-time feedback—especially disaggregated data showing top energy-consuming apps—shifted perceptions, reducing hardware’s perceived influence by 29%. Though users adopted energy-saving actions (e.g., closing idle apps, switching to lightweight software), workplace priorities often limited sustained changes. Our findings prove user-centric interventions can raise awareness, but highlight the need for context-sensitive designs that balance energy efficiency with workflow demands. This work establishes actionable pathways to reduce ICT’s carbon footprint through behavior-aware software ecosystems
Les contrats de long terme d'électricité au prisme de la justice énergétique : Annexe méthodologique
No full textPower purchase agreements (also known as PPAs) are set to partially replace state support mechanisms such as feed-in tariffs for French renewable electricity production. These contracts are also intended to accelerate the development of renewable energies. In recent years, legal provisions have been adopted to facilitate and encourage the use of these contracts in France, given that “France is lagging behind” European pioneers such as Spain and Scandinavia.In the development of PPAs and the construction and reinforcement of their legal framework, little attention has been paid to energy justice. In the current context of fluctuating and deregulated energy prices, this requirement seems more than ever inseparable from the decarbonization of the energy sector envisaged by the public authorities. Who benefits most from these contracts today? And why? What measures are planned to extend their benefits? Are these contracts a vehicle for territorializing RE production/consumption?To answer these questions, this article analyzes the development of these contracts and the construction of the legal framework on which they are based, in the light of the three pillars of energy justice. To do so, it draws on a documentary analysis including a press review, parliamentary debates and reports, a quantitative analysis of signed and publicized PPAs, and a series of interviews with renewable energy producers and purchasers who have signed PPAs, including private companies and local authorities.Il est prévu que les contrats de long terme de vente directe (aussi appelés power purchase agreement ou PPA) remplacent en partie les aides étatiques telles que les obligations d’achat pour la production d'électricité renouvelable (EnR) française. Ces contrats sont également annoncés comme un moyen d’accélérer le développement des EnR. C’est au titre d’un « retard français » en la matière par rapport à des pays européens pionniers tels que l’Espagne que des dispositions juridiques ont été adoptées ces dernières années pour faciliter le recours à ces contrats en France. Dans le développement des PPA peu d’attention a été portée par les acteurs à la justiceénergétique. Dans le contexte de fluctuation et de dérégulation des prix de l’énergie que nous connaissons actuellement, cette exigence parait plus que jamais indissociable de la décarbonation du secteur énergétique envisagée par les pouvoirs publics. A qui bénéficienten majorité ces contrats aujourd’hui ? Pour quelles raisons ? Qu’est-il prévu de mettre en place pour en généraliser les bénéfices ? Ces contrats sont-ils un vecteur d’une territorialisation de la production et de la consommation d’EnR ? Pour répondre à ces questions, cet article analyse le développement de ces contrats et de leur cadre juridique à l’aune de trois piliers de la justice énergétique. Pour ce faire, il s’appuie sur une analyse documentaire dont une revue de presse, des débats parlementaires et des rapports, une analyse quantitative des PPA ainsi qu’une série d’entretiens avec des producteurs d’énergie renouvelable et des consommateurs signataires de PPA
Does Carpooling Reduce Carbon Emissions? The Effect of Environmental Policies in France
No full textInternational audienceRoad transportation is among the most carbon-intensive sectors in the economy, underscoring the urgent need for strategies to meet climate objectives. Carpooling has emerged as a promising solution for carbon mitigation. However, by making car travel more attractive, carpooling may lead to ambiguous environmental outcomes. This study evaluates carpooling’s potential to mitigate carbon emissions and explores various strategies to enhance its environmental benefits. A key focus of this research is the vehicle occupancy rate, which we define as a robust metric for assessing carpooling’s carbon mitigation potential. This metric is reliable as it accounts for travelers’ preferences for alternative transport modes. We also analyze how policies that impact monetary trip costs influence carpooling adoption. Using a unique database from France’s leading carpooling platform, we show that increasing monetary trip costs through carbon pricing boosts both carpooling demand and supply, while improving occupancy rates. Furthermore, we find that novice users are particularly sensitive to fluctuations in monetary trip costs. In addition to this policy, we explore the effect of encouraging drivers to transition into passengers. Our results suggest that this strategy holds significant potential for further reducing carbon emissions. The insights from this study are crucial for policymakers seeking to design more effective strategies for reducing vehicle emissions and achieving climate targets
Complexification inutile et dangereuse de l'application de l'article 1843-4 du code civil
No full textInternational audience(Com. 27 nov. 2024, no 23-17.536, F-B, D. 2024. 2060 ; Rev. sociétés 2025. 130, note G. Pillet
Do digestates produced by co-digestion of biowaste and biodegradable plastic affect soil and aquatic organisms?
No full textInternational audienceThe fast development of the biogas sector requires a better understanding of potential ecotoxicological effects of digestates on both terrestrial (through digestate spreading) and aquatic organisms (through digestate soil leachate). This study is the first one to assess through a multi-species approach that include aquatic organisms short-term ecotoxicological effect in microcosm experiments of digestates (and their respective leachates) derived from biowastes co-digested or not with biodegradable plastics (PLA or PHB). Ecotoxicological tests were performed on six terrestrial/aquatic bioindicators: (1) wheat, (2) tomato, (3) soil bacteria, (4) earthworm, (5) duckweed and (6) water flea. Digestate fertilization treatments were compared to a soil not fertilized and to a mineral fertilization ensuring the same level of N (170 kg N/ha) and P (17 kg P/ha) for all fertilized treatments. No ecotoxicities of all digestates and their soil leachates were observed on wheat, soil bacteria, earthworm, duckweed and water flea following laboratory standardized procedures. Attention should be given to possible ecotoxicity of biowaste digestates (with or without biodegradable plastics) on tomato growth where a lower dry aerial biomass (23 % less in average) was observed compared to the soil chemically fertilized. For all bioindicators, no differences were observed when comparing fertilization with biowaste digestate to its equivalent co-digested with biodegradable plastics. Therefore, no apparent ecotoxicity related to the potential presence of residual biodegradable plastics in digestates was highlighted. Long-term ecotoxicological effects and repeated exposure to biodegradable plastics from digestates as well as comparison with conventional plastics are beyond the scope of this article and will require further researc