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Hybrider les chaufferies gaz par des pompes à chaleur : un compromis à trouver en termes de dimensionnement
No full textInternational audienceDécarboner le chauffage. En tertiaire, cet usage concerne 46% des consommations toutes énergies tous usages (200 TWh/an). Celui-ci est à plus de 70% issu des fossiles (60% en résidentiel collectif). Réduire nos émissions carbone passera inévitablement par l'isolation du bâti. Mais les coûts élevés de ce geste et la nécessité d'une décarbonation rapide incitent à explorer des alternatives, comme l'hybridation des chaufferies par des pompes à chaleur. Le groupe Décarbonation des Bâtiments d'EDF R&D développe un outil, pour l'hybridation des chaufferies existantes par pompes à chaleur, qui rend compte, au pas horaire, des performances constructeurs des PAC air/eau (puissance et COP). Des paramètres essentiels, parfois mal appréhendés, y sont décrits : dégivrages, performances à charge partielle
Evaluation of hydrological models on small mountainous catchments: impact of the meteorological forcings
No full textInternational audienceAbstract. Hydrological modelling of small mountainous catchments is particularly challenging because of the high spatio-temporal resolution required for the meteorological forcings. In-situ measurements of precipitation are typically scarce in these remote areas, particularly at high elevations. Precipitation reanalyses propose different alternative forcings for the simulation of streamflow using hydrological models. In this paper, we evaluate the performances of two hydrological models representing some of the key processes for small mountainous catchments, using different meteorological products with a fine spatial and temporal resolution. The evaluation is performed on 55 small catchments of the Northern French Alps. While the simulated streamflows are adequately reproduced for most of the configurations, these evaluations emphasize the added value of radar measurements, in particular for the reproduction of flood events. However, these better performances are only obtained because the hydrological models correct the underestimations of accumulated amounts (e.g. annual) from the radar data in high-elevation areas
One step bio-guided isolation of secondary metabolites from the endophytic fungus Penicillium crustosum using high-resolution semipreparative HPLC
No full textInternational audienceAn endophytic fungal strain Penicillium crustosum was isolated from the seagrass Posidonia oceanica and investigated to identify its antimicrobial constituents and characterize its metabolome composition. The ethyl acetate extract of this fungus exhibited antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) as well as an anti-quorum sensing effect against Pseudomonas aeruginosa. The crude extract was profiled by UHPLC-HRMS/MS and the dereplication was assisted by feature-based molecular networking. As a result, more than twenty compounds were annotated in this fungus. To rapidly identify the active compounds, the enriched extract was fractionated by semi-preparative HPLC-UV applying a chromatographic gradient transfer and dry load sample introduction to maximise resolution. The collected fractions were profiled by 1 H-NMR and UHPLC-HRMS. This method led to the unambiguous identification of eight known secondary metabolites as well as the determination of their bioactivity using a single purification step
Mesures robotisées : caractérisation acoustique automatisée des structures
No full textThis thesis aims at developing a tool for automated acoustic characterization using robotized measurements. Leveraging advancements in robotics, mechanics, and applied mathematics, the work focuses on employing a robotic arm equipped with sensors to estimate the sound field emitted by unknown structures. Since the accuracy of the measurements depends on the precise positioning of the sensor, discrepancies between the nominal and actual models of the robotic arm must be corrected. To address this, a comprehensive geometric calibration procedure is proposed and experimentally validated through two case studies involving three robotic arms and two types of sensors. Notably, significant improvements in accuracy are achieved by incorporating task-specific and sensor-infused features. The theoretical and numerical foundations of Sound Field Estimation (SFE), which aims at reconstructing the acoustic field radiated by an unknown source based on a limited set of measurements, are then explored. Among the reviewed methods, the Boundary Elements Method (BEM) stands out for its efficiency and flexibility despite its computational cost. Numerical simulations allow for the validation of the method's performances and the analysis of its robustness in the presence of external disturbances, highlighting the importance of robot calibration to ensure reliable results. Finally, to support the experimental implementation of our tool, a framework based on the ROS middleware is introduced to manage interfaces between the robot, sensors, and their environment. Prior to acoustic measurements, a robotized geometric characterization process is presented to determine the shape and position of the studied object. The robotized setup developed to automate acoustic measurements is then presented, with particular focus on the effects of the robot on the measurements. Under conditions where these effects are minimized, two autonomous measurement campaigns led to a successful reconstruction of the sound field radiated by an unknown loudspeaker, demonstrating the potential of the proposed tool.Cette thèse a pour but le développement d'un outil de caractérisation acoustique automatisé à l'aide de mesures robotisées. En s'appuyant sur des avancées en robotique, mécanique et mathématiques appliquées, les travaux réalisés traitent de l'utilisation d'un bras robotisé équipé de capteurs pour estimer le champ sonore émis par des structures inconnues. La précision des mesures dépendant de l'exactitude du positionnement du capteur, les écarts entre les modèles nominaux et réels du bras robotisé doivent être compensés. Pour cela, une procédure complète d'étalonnage géométrique est proposée et validée à travers deux études de cas impliquant trois bras robotisés et deux types de capteurs. En particulier, des améliorations significatives de la précision sont obtenues en intégrant des aspects spécifiques à la tâche visée et aux capteurs utilisés. Les fondements théoriques et numériques de l'estimation de champ sonore, qui vise à reconstruire les champs acoustiques rayonnées par une source inconnue à partir d'un ensemble limité de mesures, sont ensuite explorés. Parmi les méthodes examinées, la méthode des éléments de frontières se distingue par son efficacité et sa flexibilité, malgré ses exigences computationnelles. Des simulations numériques permettent la validation des performances de la méthode et l'analyse de sa robustesse en présence de perturbations externes, soulignant l'importance de l'étalonnage du robot pour garantir des résultats fiables. Finalement, afin d'assurer la mise en œuvre expérimentale de notre outil, un "framework" reposant sur le middleware ROS est introduit pour gérer des interfaces entre le robot, les capteurs et leur environnement. En amont des mesures acoustiques, un procédé de caractérisation géométrique robotisé permettant de déterminer la forme et la position de l'objet étudié est présenté. Le système de mesures acoustiques robotisées est ensuite décrit, avec une attention particulière portée aux effets du robot sur les mesures réalisées. En se plaçant dans des conditions où ces impacts sont limités, deux campagnes d'acquisition autonomes nous permettent de reconstruire avec précision le champ sonore rayonné par une enceinte inconnue, démontrant ainsi le potentiel de l'outil développé
A simplified method for thermal buckling verification in steel–concrete composite elements
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Effect of maximum packing fraction of powders on the rheology of metakaolin-based geopolymer pastes
No full textInternational audienceIn this work, we study the effect of maximum packing fraction of powders on the rheology of geopolymer pastes. A large range of metakaolin powders is generated either by blending or grinding powders. Blends of metakaolin with quartz and limestone are also studied. We show that the compressive packing model is able to predict correctly over a wide range of values the maximum packing fraction of these powders. We show that an increase of the maximum packing of powders leads to a decrease of the viscosity of geopolymer suspension at a constant solid volume fraction. We finally show that the viscosity of studied geopolymer suspensions can be well predicted by the Krieger Dougherty relation. We suggest that the highest potential degree of freedom allowing for the control of the viscosity of geopolymer pastes without modifying the composition of the suspension lies in the maximum packing fraction of the solid powders
Uncertainties in numerical predictions and experimental characterization of wind farm noise
No full textInternational audiencePIBE (Prévoir l’Impact du Bruit des Éoliennes – Predicting the impact of wind-turbine noise) is a research project funded by ANR (French National Research Agency) which main objectives are to better understand the noise levels created by wind-turbines and assess noise-reduction solutions. One topic of this project focuses on the propagation of uncertainty. Code_TYMPAN™ is an open-source software for calculating industrial noise in the environment. Its open architecture, implemented by a Python API, allows advanced users to build and solve models programmatically. This open architecture made possible the implementation of a parametrical computational tool (OCP – Outil de Calcul Paramétrique). This tool generates input data, launches the calculations with Code_TYMPAN™, generates and post-processes output data. Thus, sensitivity analysis and propagation of uncertainty were performed on an industrial test case. This development demonstrates the feasability of introducing uncertainties in acoustic engineering studies
Diagnostic Performance of 18F-FDG PET/CT According to Delay After Treatment to Detect Subclinical Recurrence of Head and Neck Squamous Cell Carcinoma
No full textInternational audienceHead and neck squamous cell carcinoma (HNSCC) remains a malignancy with high rates of locoregional recurrence and poor prognosis for recurrent cases. Early detection of subclinical lesions is challenging but critical for effective patient management. Imaging surveillance after treatment, particularly 18F-FDG PET/CT, has shown promise in the diagnosis of HNSCC recurrence. The aim was to evaluate the diagnostic performance of 18F-FDG PET/CT according to delay after treatment in detecting subclinical recurrence (SCR) in HNSCC patients. Methods: In this retrospective study, all 18F-FDG PET/CT scans were performed at a single center. All adults with histologically proven HNSCC who were treated with curative intent between January 1, 2006, and December 31, 2021, were included. They had a normal clinical examination before each scan. Patients who underwent an intensive follow-up strategy after treatment had 18F-FDG PET/CT with an intravenous contrast agent at 3-6 mo and annually thereafter for 5 y. The primary endpoint was diagnostic performance (positive and negative predictive values, sensitivity, specificity, and accuracy). Results: In total, 2,566 18F-FDG PET/CT scans were performed among 852 patients, with an average of 3 scans per patient. The overall diagnostic performance measures were as follows: positive predictive value (88%), negative predictive value (98%), sensitivity (98%), specificity (89%), and accuracy (93%). There were no significant differences in diagnostic performance over time. The scans detected 126 cases of SCR (14.8%) and 118 cases of metachronous cancer (13.8%). The incidence of SCR decreased over time, with the highest detection rate in the first 2 y after treatment. Positive predictive value improved over time, reaching 90% for the digital Vision 600 system (third period) compared with 76% for the analog Gemini GXLi system (first period, P < 0.001). Multivariate analysis identified advanced stage, high body mass index, and initial PET/CT upstaging as predictive factors for detection of SCR. Conclusion: Our study demonstrates that 18F-FDG PET/CT has high diagnostic performance in detecting SCR during follow-up after treatment of HNSCC, especially in the first 2 y. Advanced tumor stage, initial PET/CT upstaging, and high body mass index were associated with a higher likelihood of SCR detection. The routine use of 18F-FDG PET/CT during follow-up seems justified for patients with HNSCC. © 2024 by the Society of Nuclear Medicine and Molecular Imaging
An algorithm for computing scattering poles based on dual characterization to interior eigenvalues
No full textInternational audienceWe present an algorithm for the computation of scattering poles for an impenetrable obstacle with Dirichlet or Robin boundary conditions in acoustic scattering. This paper builds upon the previous work of Cakoni et al . (2020) titled ‘A duality between scattering poles and transmission eigenvalues in scattering theory’ (Cakoni et al . 2020 Proc. A. 476 , 20200612 ( doi:10.1098/rspa.2020.0612 )), where the authors developed a conceptually unified approach for characterizing the scattering poles and interior eigenvalues corresponding to a scattering problem. This approach views scattering poles as dual to interior eigenvalues by interchanging the roles of incident and scattered fields. In this framework, both sets are linked to the kernel of the relative scattering operator that maps incident fields to scattered fields. This mapping corresponds to the exterior scattering problem for the interior eigenvalues and the interior scattering problem for scattering poles. Leveraging this dual characterization and inspired by the generalized linear sampling method for computing the interior eigenvalues, we present a novel numerical algorithm for computing scattering poles without relying on an iterative scheme. Preliminary numerical examples showcase the effectiveness of this computational approach