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Calibration of non-local damage models from full-field measurements: Application to discrete element fields
No full textInternational audienceContinuous damage models are increasingly used in numerical simulations to design structures, but their local formulations are sensitive to mesh size and present localization of strains in an infinitely thin region. To overcome these problems non-local damage models and related regularization methods, have been developed introducing a characteristic/internal length, thus avoiding pathological mesh dependence. Those methods make the damage evolution depends on the mechanical quantities at the current material point (local) and its neighborhood (non-local).Existing approaches to calibrate the internal length use global quantities in the calibration process, although local data is now becoming accessible (e.g., using digital image correlation). In this study, we investigate the use of full-field displacement measurements and propose a new methodology for calibrating a non-local damage model based on local field measurements and we apply it to calibrate the Eikonal Non-local Gradient (ENL-G) approach from the measured strain and damage field. After detailing the calibration procedure, we then apply it on a simple ideal case. We illustrate, and analyze the robustness of the calibration procedure with respect to the choice of evolution law and measurement noise of the proposed calibration method. To confront the procedure to a more realistic case, we employed a 2D beam-particle model. This discrete model is first identified with respect to the size and shape effect based on one of the comprehensive experimental data sets available in the literature, including four shapes with three sizes each. Then, it is used to generate a “reference” evolution of the damage and strain fields in beams of different sizes subjected to uniaxial tension.The parameters of the discrete model used have been calibrated to represent the scale and size effects, giving a very good representation of the experiments. We also illustrate the evolution of non-local interactions in the Eikonal approach using Green functions. Finally, the application of the calibration procedure shows that it is possible to determine the internal length of the non-local problem studied as well as the damage evolution law and its parameters. The outcomes of this study contribute to shed light on a new methodology to identify non-local damage models based on full-field measurements, and call for experimental size effect campaign with displacement field
Simulation-free Reduced-order Modeling using Invariant Manifolds
No full textInternational audienceThis chapter introduces the concept of invariant manifold as a key tool for model order reduction of dynamical systems
Real-World Asphalt Pavement Emissions: Combining Simulation Chamber Measurements and City Scale Modeling to Elucidate the Impacts on Air Quality
No full textInternational audienceIn this paper, the role of asphalt pavement emissions in urban air quality was assessed combining laboratory experiments and city-scale air-quality modeling. In particular, the emission factors (EFs) of volatile and intermediate volatility organic compounds (VOCs and IVOCs) of asphalt pavements were determined in an atmospheric simulation chamber. Relative humidity (RH) and simulated solar light UV-A radiation were found to play a key role in the emission of VOCs and IVOCs. RH significantly increased the EFs, and predominantly those of oxygenated VOCs, due to changes in the microphysical properties of the materials. Under UV-A radiation, EFs were enhanced, due to the photochemical process induced on the asphalt–air interface. IVOCs were found to account for up to 30% of the Total EFs measured. Considering Paris as a case study, asphalt emissions in air-quality simulations lead to an increase in organic aerosol concentrations of at least 3%, during average summer daytime conditions. We estimate this impact significantly higher, in case all the IVOCs emissions are included in the model. This highlights the significant influence of solar radiation on emissions from old asphalt when exposed to UV radiation and the impact on air quality during the summer
L’hypothèse du continuum bipolarité-schizophrénie au risque psycholinguistique des ruptures discursives
No full textInternational audienceTopicThe relationship between bipolarity and schizophrenia has been the subject of research in neurosciences, neuropsychology and cognitive psychopathology over the past few decades. This research has led to the formulation of a hypothesis suggesting that the two pathologies might be situated on a continuum. This hypothesis has been incorporated into the most recent mental disorders classifications with the introduction of the “schizoaffective disorder”, which encompasses both psychotic and thymic symptoms. In this study, we examine the hypothesis of such a continuum in the context of the pragmatic discontinuities that occur in dialogue with a psychologist and either a schizophrenic or a bipolar patient. Furthermore, the aim is to delineate the cognitive and psycholinguistic impairments observed in the schizophrenic group in comparison to the bipolar group.MethodologyThis study compares two matched corpora of clinical interviews with patients diagnosed with bipolar disorder and schizophrenia, conducted under identical conditions. To ensure the highest level of anonymity, the two corpora were disidentified. The interviews were conducted in a non-directive manner, with the objective of creating a conducive environment for the patients to express themselves freely, to enhance their confidence and to maintain the interaction as long as possible. During the course of the conversation, the patients were never contradicted.In order to create two balanced corpora, portions of the larger schizophrenia corpus were removed. Subsequently, an exhaustive search was conducted through inter-judge agreement to identify “discontinuities”, defined as specific breaks in a dialogue, which indicate incoherence in the dynamical structure of discourse. The concept of “discontinuity” has been previously formalized and is based on a precise definition of the patients’ involvement in the dialogue and their ability to maintain coherence in their discourse. These pragmatic discontinuities were then formally analyzed using “hierarchical modelling”, which reveals the dynamic structuring of the speech acts in a dialogic interaction and objectively highlights the discontinuities.ResultsA total of 25 discontinuities were identified in both corpora. The aforementioned discontinuities were observed in three bipolar conversational sequences and 11 schizophrenic ones. The sequences were then classified into categories in accordance with the principal features of their discontinuities. Firstly, three of the schizophrenic sequences were found to exhibit an “inaccessible non-literal meaning”. The sequences in question exhibit an oddity to such an extent that the meaning of the sequence is “broken” by the discontinuity. Secondly, four schizophrenic sequences were identifier and designated as “loss of the non-literal meaning”. In such instances, the schizophrenic patients exhibit a regression process whereby they return to a more basic and literal lexical content, from a rich and figurative meaning of the same lexical entry. Thirdly, two schizophrenic sequences are distinguished by the phenomenon of “semantic and/or lexical switches”. This entails a transition from a lexical entry to another, which frequently occurs multiple times. The aforementioned switches result in a loss of coherence until a discontinuity occurs. The category “semantic and/or phonological associations” comprises two schizophrenic sequences in which either a meaningless portmanteau word or an oxymoronic phrase is observed. A single bipolar sequence is associated with one of the aforementioned categories, which is also characteristic of schizophrenia. The category “semantic and/or lexical switches”. The two last bipolar sequences demonstrate, firstly, a “violation of the pragmatic use of a discursive marker” and secondly a “perturbation of the reference access”. The first sequence presents an argumentative marker “parce que” (i.e. because) which is not followed by any causes of the above. The second sequence displays a sudden shift: a highly cohesive sequence referencing a person is abruptly disrupted by a discontinuity when the bipolar patient refers to another individual.A total of 21 discontinuities were identified in the schizophrenic corpus, while the bipolar corpus exhibited four discontinuities. As a result, common pathological discourse features are proposed for consideration in relation to the two tested groups, although two distinct levels of this pragmatic disorder are clearly observable. To this end, a series of Fischer exact statistical tests were conducted on the number of relevant discourse events with respect to the number of words for each group. The statistical results demonstrate that the extension and variability of pragmatic discourse disorders are significantly more frequent and extensive in interactions with schizophrenic patients than with bipolar patients. However, we also observed that impaired psycholinguistic processes associated with the management of lexical entities and the conveyance of meaning are common to both schizophrenic and bipolar groups.ConclusionThe specific hierarchical and dynamic discourse analysis methodology can be used to assist in the diagnosis of bipolar disorder and to facilitate the recognition of symptoms and prodromal signs of schizophrenia. Furthermore, it can also be employed to elucidate the psycholinguistic processes underlying the verbal expression of bipolar and schizophrenia disorders. In addition, it offers a novel perspective on the hypothesis of a continuum between schizophrenia and bipolar disorders by delineating the psycholinguistic processes that underpin discourse competence. This psycholinguistic cognitive disorder manifests the patients’ inability to regulate both the propositional content of their utterances and the semantic implications attached to them. Thus, we observe in both the two groups that the interaction is maintained “at all costs”: all patients continue the interaction, even if the cost is the discontinuity leading to incoherence. We hypothesize that maintaining the interaction leads to an increase in cognitive effort throughout the thematic unit, which can be extensive. When the cognitive effort becomes too great, the discontinuity occurs to reduce this effort and thus allow the interaction to continue until the end of the current thematic unit. This conclusion is strictly the same from the schizophrenic patients to the bipolar patients.SujetLa recherche en neurosciences et en psychopathologie cognitive sur les rapports entre bipolarité et schizophrénie a évolué dans le temps pour aboutir à l’hypothèse d’un continuum entre les deux pathologies. Nous discutons cette hypothèse sur le plan des discontinuités discursives qui surviennent dans l’entretien clinique.MéthodologieNous comparons deux corpus d’entretiens cliniques appariés, réalisés avec des patients bipolaires et, dans les mêmes conditions, avec des patients schizophrènes. L’entretien est non directif ce qui encourage la libre parole du patient. Les deux corpus comportent le même nombre de mots. On y effectue une recherche exhaustive des « ruptures » à l’appui d’un modèle d’investigation de la désorganisation discursive sensible aux propriétés linguistiques et illocutoires des actes de langage. Ces « ruptures » sont alors analysées formellement au moyen de la modélisation hiérarchique qui met au jour les relations défectueuses qu’entretiennent les actes de langage dans la structuration dynamique des séquences conversationnelles.RésultatsLe test « Fischer exact » est fait sur le dénombrement des évènements discursifs pertinents au regard du nombre de mots pour chaque groupe. Les résultats statistiques montrent que l’extension et la variabilité des troubles du discours est largement plus fréquente et bien plus étendue dans l’interaction avec les schizophrènes qu’avec les bipolaires. Pourtant, des processus psycholinguistiques défaillants associés à la gestion de la signification des entités lexicales sont communs aux deux groupes.ConclusionNotre méthodologie d’analyse du discours, hiérarchique et dynamique, vaut pour un instrument d’aide au repérage de certains troubles bipolaires autant que pour la reconnaissance des symptômes schizophréniques. Elle permet aussi de préciser les processus psycholinguistiques associés à l’expression des troubles bipolaires et schizophréniques en interaction verbale. Elle permet enfin de contribuer à l’hypothèse du continuum entre schizophrénie et bipolarité à l’appui des processus cognitifs de haut niveau étayant la compétence discursive
Nouvelle approche pour étudier le phénomène d'hydruration secondaire sur les gaines M5Framatome dans des conditions d'APRP
No full textInternational audienceThe focus of this study is about a new experimental approach for a separate effects study of the secondary hydriding phenomenon under LOCA conditions. Many nuclear institutes perform semi–integrals tests to study the cladding behaviour during a LOCA transient. Those tests combined several phenomena and performing a detailed analysis of the secondary hydriding phenomenon using these tests can be challenging. A dedicated experimental protocol aiming at simulating secondary hydriding has been set up. Separate effects tests (SETs) were then carried out using this protocol to study the effects of both oxidation duration and temperature, on the hydrogen absorption during the oxidation stage of the LOCA transient on M5Framatome1 cladding. The effects of gap size were also investigated. Metallographic analysis has been used to characterise the M5Framatome clad metallurgical transformation after the high–temperature (HT) oxidation
Evaluation de petits modèles de langues (SLM) sur un corpus de Sciences Humaines et Sociales (SHS) en français
No full textNational audienceCet article évalue une série de plusieurs petits modèles de langues (SLM) sur une tâche de classification de tweets en français. Plusieurs stratégies d’optimisation sont testées : différents prompts (zero-shot, few-shot), fine-tuning avec une couche de classification, présence ou non d’une couche LoRa. Les résultats obtenus avec le modèle Qwen optimisé rivalisent avec un modèle beaucoup plus gros, ce qui valide notre intérêt pour les petits modèles
Orchestrating an interoperable sovereign federated Multi-vector Energy data space built on open standards and ready for GAia-X D6.2 OMEGA-X Use case family implementation report
No full textThis document is a report that outlines the implementation plan for carrying out pilot activitieswithin the OMEGA-X project. It is based on the work performed in tasks T6.2 "Renewable UseCase Family", T6.3 "Energy Communities and Sector Integration Use Case Family", T6.4"Collaboration among Electromobility Actors Use Case Family", and T6.5 "Flexibility Use CaseFamily". It covers various aspects, including the methodology used, the OMEGA-Xarchitecture, the implementation of data blocks, and the specific implementation for each pilotsite. This is a first step toward the final report on lessons learned and KPI evaluation that willcapitalize on all the effort made in OMEGA X to demonstrate the feasibility of data and servicesinteroperability among energy sector in Europe
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
Gaussian Processes: from knowledge-informed Machine Learning to optimization
No full textNational audienceMany situations lead to sparse data or uncertain data. Gaussian processes (GPs) offer a mathematically funded framework for learning, optimizing,and other decision-making activities. This poster, presented at the HCERES* audit of the LIMOS laboratory in 2025, summarizes several contributions of the St-Etienne applied mathematics team of the LIMOS made between 2023 and 2025. * HCERES : Haut Conseil de l'Evaluation de la Recherche et de l'Enseignement Supérieu