HAL-EMSE
Not a member yet
9132 research outputs found
Sort by
Investigation of [BMIM]FeCl<sub>4</sub> ionic liquid as an additive for carbon capture using gas hydrates with seawater
No full textInternational audienceCarbon capture through gas hydrate formation represents a highly promising avenue for mitigating greenhouse gas emissions. The unique structure of gas hydrates allows for the efficient trapping of gases like CO2, potentially offering a robust solution for carbon sequestration. However, the practical implementation of this technology faces several challenges, primarily related to the kinetics of hydrate formation and the stability of hydrates under varying conditions. The use of promoters has shown potential in overcoming some of these kinetic barriers. A few years ago, iron-based ionic liquids were studied as kinetic promoters for gas hydrates. Since hydrate formation kinetics pose a well-known challenge for developing hydrate-based technologies, this study aims to evaluate the effectiveness of [BMIM]FeCl4 ionic liquid for carbon capture from seawater. The research is divided into three stages: analyzing the influence of NaCl concentration on the liquid–liquid equilibrium of brine and ionic liquids; examining the thermodynamic equilibrium of CO2 hydrates in the presence of seawater and ionic liquids; and investigating the kinetics of hydrate formation. The first stage produced a two-phase ternary diagram relevant to expected industrial conditions, and the kinetic constants for gas-to-liquid and liquid-to-hydrate mass transfer were estimated. The results demonstrated a thermodynamic inhibition effect for CO2 hydrates. However, from a kinetic perspective, no significant improvement was observed. Consequently, [BMIM]FeCl4 did not prove to be an effective overall promoter
Efficient constrained Gaussian process approximation using elliptical slice sampling
No full textInternational audienceIn this paper, Bayesian shape-restricted function estimation using constrained Gaussian processes (GPs) is revisited. The GP approximation proposed by Maatouk and Bay (2017) is considered, which satisfies a wide range of shape constraints, such as monotonicity, convexity, and boundedness constraints across the entire domain. To generate samples from the resulting posterior distribution, we employ a recently efficient circulant embedding technique. This technique involves incorporating a smooth relaxation of the constraint set into the likelihood, a prior distribution, and an efficient Markov chain Monte Carlo (MCMC) sampler. Our contribution in this article is fourfold. First, we extend this approach to address sets of general linear inequalities, enabling the incorporation of multiple and complex shape constraints. This generalization allows the proposed methodology to be easily adapted to other Bayesian linear models.We derive an efficient formula for the log-likelihood function that significantly reduces computational complexity and improves runtime efficiency in high-dimensional settings. Second, we update the approximation parameter of the set of linear constraints at each MCMC iteration.This ensures the stability and the convergence of the proposed MCMC sampler. Third, we explore efficient samplers for generating posterior and prior distributions, including Hamiltonian Monte Carlo and the Fast Fourier Transform. Additionally, we adopt a large-scale, highly efficient approach for prior sampling, yielding significant computational advantages.Fourth, we investigate the capability of this approach to handle higher-dimensional input spaces and manage a large number of observations. The proposed approach demonstrates excellent flexibility and accuracy in both synthetic and real-world data studies
Orchestrating an interoperable sovereign federated Multi-vector Energy data space built on open standards and ready for GAia-X: D2.4 Data Space initiatives/projects in EU and BRIDGE alignment.
No full textThe document is OMEGA-X_D2.4, which updates OMEGA-X_D2.3 published in April 2024. Updates on Data Space initiatives and sister projects have been conducted. All the changes are using a blue colour. All new or updated sections are tagged. OMEGA-X_D2.4 “Data Space initiatives/projects in EU (European Union) and BRIDGE alignment, Final Release” is an update of OMEGA-X_D2.3 and includes a third assessment of data space initiatives at EU level, identification of use cases specified in sister projects, and monitoring of cross-domain actions. This deliverable implements the methodology outlined inOMEGA-X_D2.1 “Foundations for a holistic iterative methodology”. This strategic vision has been operationalised into a template targeted at assessing data space initiatives and sister projects. Four energy data space initiatives have been assessed for this second iteration, the four that have rallied a business alliance called DSBA (Data Space Business Alliance) and that currently are most influential in the domain of European data spaces: Gaia-X, IDSA (International Data Spaces Association), BDVA/DAIRO (Big Data Value Association/ Data, AI and Robotics) and FIWARE. Additionally, OMEGA-X aims at collaborating with four projects that are funded under the same call: Enershare, Data Cellar, Synergies and EDDIE. The current assessment is an update of the assessment conducted and described in OMEGAX_D2.3, as a result of the several energy data spaces project cluster meetings held duringM12-M24 and the outcomes of the Energy Data Spaces Interoperability Task Force led by IDSA in Bilbao. Harmonization of architectural frameworks and assets of the four data space initiatives assessed has been achieved during this second iteration. In particular, collaboratively with the sister projects, int:net a Minimum Viable Product (MVP) of an energy data space and four system use cases to demonstrate the technical interoperability amongst sister projects have been defined. This is explained in more detail in section 4.5. Semantic interoperability in the energy domain has not been addressed yet by these fourdata space initiatives because they were especially focussed on semantic interoperability of more generic domains like identity and trust, data management, security and reliability. Recent task forces have been launched by several data space initiatives to tackle semantic interoperability in energy domain and the situation should evolve rapidly. During the seconditeration phase, OMEGA-X has defined an Agile Interaction Model based Methodology for Energy data spaces (AIME), relying on four principles: agility, re usability of standards, use case-centric business-driven approach, and modularity. The methodology leverages some core standards like IEC CIM (Common Information Model) Model and associated profiles, and OMEGA-X is aligned with EU regulation on-going development (implementing act on metering and consumption data [1], demand response) developed by Joint working group ENTSO-Eand EU DSO (Distribution System Operator) entity. As a first step toward semantic interoperability between sister projects, workshops will be organized with int:net and sister projects to explain this methodology. Furthermore, as an outcome of AIME, OMEGA-X has developed general ontological modules for energy data exchange that can serve as a starting point for semantic data alignment between sister projects
Detecting Mean Shifts in a Class of Time Series CHARN Models with Application to Financial Data
No full textInternational audienceIn this paper, we propose a fully automated method for detecting changes in the mean of piecewise Conditional Heteroskedastic Autoregressive Nonlinear (CHARN) models. Detecting weak changes, those of small magnitude, is crucial in financial and economic applications, where they may signal important structural breaks. Our approach combines an adaptive model selection algorithm with a robust break detection procedure based on local power estimation. By dynamically selecting the most appropriate model for each stationary segment, the method reduces false alarms and improves sensitivity to subtle transitions. Applied to financial datasets such as the S&P 500 and FTSE 100 indices, the algorithm operates automatically and not only reproduces known breakpoints documented in the literature, but also uncovers previously undetected structural changes. These additional findings correspond to meaningful real-world events, highlighting the effectiveness and reliability of the proposed framework for analyzing financial time series and its potential value for financial stability, trading strategies, and risk management
"Repenser la Conception et la Consommation - le Défi d’une Soutenabilité Forte" - Séminaire D-TechnoSS
No full textCette planche synthétise sous forme d’illustrations graphiques les réflexions menées lors de la table ronde “Repenser la Conception et la Consommation - le Défi d’une Soutenabilité Forte” dans le cadre du séminaire D-TechnoSS - 8 juillet 2025.Depuis les années 1970, le rapport Meadows a mis en évidence la crise socio-écologique actuelle. La dernière décennie a vu une prise de conscience collective et la nécessité de lutter contre le changement climatique, ce qui entraîne une mobilisation pour développer des connaissances, des réglementations et des technologies visant à intensifier la décarbonation de la société. En réalité, le changement climatique n’est qu’une des six limites planétaires déjà dépassées aujourd’hui (Richardson et al., 2023 ; Rockström et al., 2009 ; Steffen et al., 2015). La plupart des actions mises en place pour répondre aux défis socio-écologiques restent axées sur des approches techno-centrées et/ou ne remettent pas en question le modèle économique actuel. Ces actions, fondées sur l’économie circulaire, les technologies vertes, l’éco-conception, les modèles économiques traditionnels et les stratégies de décarbonation, demeurent insuffisantes pour relever les défis socio-écologiques mis en évidence par l’économie du donut (Brozovic, 2020 ; de Oliveira Neto et al., 2018 ; Raworth, 2017 ; Vilochani et al., 2024). Il est devenu important de développer de nouvelles démarches de co-construction des solutions soutenables entre les concepteurs et les consommateurs et des modes de consommation plus durables pourraient sans doute favoriser une transition vers une soutenabilité forte. Ce séminaire a pour objectif d’approfondir le concept de soutenabilité forte ainsi que sa relation avec les comportements du consommateur et les produits et services intégrant les enjeux socio-écologiques en conception. Il s'inscrit dans le cadre du projet D-TechnoSS financé par l’ANR et mené par l’Université de Technologie de Troyes, l’École des Mines de Saint-Étienne et l’Université Paris Nanterre. Il vise à développer une meilleure compréhension des mécanismes de changements des comportements afin d'adopter des démarches de co-construction de soutenabilité forte
Prendre la mesure du coût résidentiel et de ses enjeux au sein des territoires
No full textInternational audienceThe concept of residential cost has gradually emerged in the context of growing interestin taking into account the interactions between residential location, housing and mobility,and thus gaining a better grasp of the social and environmental issues involved interritorial dynamics. However, the existing statistical data, built up in thematic silos,do not allow this concept to be used to see whether it provides a relevant response tothese questions. This article assesses the experiment of a ‘residential cost’ module inthe latest local travel survey carried out in the greater Grenoble region over the period2019 and 2020 (a French EMC² certified by the public institution CEREMA). Onthe one hand, it shows the capacity of such a module, integrated into a local travelsurvey, to provide a robust estimate of the residential cost of the households surveyed.Secondly, it provides initial results on the residential cost of households as a function oftheir residential location and income, showing the value of such a concept for understandingthe economic constraints faced by the most modest households. The results ofthis experiment suggest that an optional ‘residential cost’ module could be developedas a back-up to the French EMC²s, to provide a clearer picture of the impact of localpolicies on the interaction between mobility and housing.La notion de coût résidentiel a progressivement émergé dans le contexted’un intérêt croissant pour prendre en compte les interactions entrelocalisation résidentielle, logement et mobilité, et ainsi mieux saisirles enjeux sociaux et environnementaux des dynamiques territoriales.Cependant, les données statistiques existantes, construites en silos thématiques,ne permettent pas d’outiller cette notion pour voir si ellerépond de manière pertinente à ces interrogations. L’article tire un bilande l’expérimentation d’un module ‘coût résidentiel’ au sein de la dernièreEnquête Mobilité Certifiée Cerema (EMC²) réalisée sur la granderégion de Grenoble sur la période 2019 et 2020. D’une part, il montre lacapacité d’un tel module, intégré à une enquête déplacements locale, àfournir une estimation robuste du coût résidentiel des ménages enquêtés.D’autre part, il fournit de premiers résultats sur le coût résidentieldes ménages en fonction de leur localisation résidentielle et leur revenu,montrant l’intérêt d’une telle notion pour comprendre les contrainteséconomiques que connaissent les ménages les plus modestes. Les résultatsde cette expérimentation permettent ainsi d’envisager le développementd’un module optionnel ‘coût résidentiel’ adossé aux EMC²françaises et permettant de mieux éclairer les politiques territorialeslocales sur leurs conséquences en matière d’interactions entre mobilitéet logement
High temperature chromium coating cracking investigation during tensile tests monitored by acoustic emission
No full textInternational audienceThe present study focuses on in-situ measurements of crack initiation and propagation in first-generation PVD-HiPIMS chromium coatings on M5Framatome11M5Framatome is a trademark or a registered trademark of Framatome or its affiliates in the USA or other countries. cladding substrates using an acoustic emission (AE) device and a tensile test machine. A key novelty of this work is the implementation of a temperature-controlled cracking monitoring system adapted to the cladding geometry under tensile loading. Post-mortem examinations (after different interrupted tensile tests) provide an evaluation of the in-situ method for determining the crack initiation threshold and crack density evolution. The critical strain to crack initiation increases exponentially from 0.4 % at room temperature to 3 % at 350 °C. Above 410 °C, the coating no longer exhibits brittle cracking until reaching high macroscopic imposed strain (up to 30-50 %). Additionally, the crack density decreases more or less linearly with the increasing testing temperature. At higher temperatures, the coating becomes highly ductile, consistently with the increased plasticity of pure chromium. SEM observations of the coating cross-section confirm that cracks do not propagate beyond the coating and that no delamination occurs. Thus, after rapidly reaching crack density saturation, the residual uncracked chromium coating exhibits significant plasticity and widening of the existing Cr cracks while providing slight mechanical reinforcement to the Zr-based cladding up to at least 400 °C
Robust Possibilistic Programming Approach to Production Scheduling of Reconfigurable Manufacturing System Based on Learning Effect
No full textInternational audienceThe emergence of reconfigurable manufacturing offers innovative solutions for efficientlyadapting to changing market demands and system modifications. This paper introduces a robustpossibilistic programming framework to address a multi-objective production scheduling problemwithin sustainable reconfigurable manufacturing systems, incorporating uncertainty. The model capturesthe workforce learning effect on reconfiguration times, aiming to minimize makespan, productioncosts, and social sustainability while considering uncertain parameters. Possibilistic chance-constrainedprogramming and robust possibilistic programming approaches are applied to assess both model andsolution robustness. Additionally, the framework addresses workplace safety risks linked to workforceassignments and incorporates workforce entry preferences for flexible hours. By considering the learningeffect in reconfiguration times, the model reflects the dynamic nature of scheduling, aligning moreclosely with real-world scenarios. The augmented epsilon-constraint method is also used to efficientlyfind Pareto-optimal solutions for the multi-objective model
Entre justice et image : les fonctions de la peine dans la doctrine criminelle et politique (XVIe-XVIIIe siècles)
No full textInternational audienc
Penser l’innovation durable au service d’une économie circulaire dans le secteur de la santé
No full texthttps://www.eclaira.org/Dans un contexte marqué par des crises environnementales, sanitaires et socioéconomiques de plus en plus fréquentes, il devient nécessaire de repenser nos systèmes de production et de consommation pour tendre vers des modèles plus durables. Le secteur de la santé, souvent considéré à part du fait de sa mission sociale, n’échappe pourtant pas à cette exigence de transformation. Réduire l’empreinte environnementale des activités de soin tout en maintenant un haut niveau de qualité et d’accessibilité représente un défi majeur. À ce titre, l’économie circulaire offre des leviers intéressants, encore peu mobilisés dans ce domaine. Leur mise en œuvre suppose cependant de conjuguer innovations organisationnelles, technologiques et sociales, au sein des établissements de santé comme à l’échelle territoriale.Ce texte propose de montrer comment articuler innovation durable, économie circulaire et secteur de la santé. Il mettra également en lumière quelques pistes concrètes d’action