Forming Process Simulation for Fabrication Optimization in Areva Creusot Forge and Industeel

International audienceThe grain size of the austenitic stainless steel is an important issue for parts such as primary pipes in nuclear power plants and more globally for metal forming. Having tools which can predict at least the final grain size distribution for these materials is strongly required. It is in this frame that ACF worked for several years with other industrial and academic partners such as INDUSTEEL CRMC, Aubert & Duval, Ascometal, CEA Valduc and CEMEF Mines ParisTech on the simulation of the recrystallization (ReX) of 304L austenitic stainless steel. Recent developments allowed simulation in a full-field context of the static recrystallization (SRX) of 304L stainless steel including a crystal plasticity formulation in a finite element (FE) context in order to model precisely the grain deformation anisotropy. This crystal plasticity model includes a decomposition of the dislocation density in SSDs (Statistically Stored Dislocations) and GNDs (Geometrically Necessary Dislocations). Including the GNDs gave better results on the localization of the strain but also allowed to define more relevant nucleation criteria. During and after ReX, the grain growth phenomenon due to capillarity effects is also modelled. To take into account capillarity effects enables to reproduce precisely the final microstructure morphology (shape of the grains, equilibrium angles at multiple junctions...). This full-field approach gives very good results for the modelling of 304L stainless steel SRX. In parallel, at plants, forging and rolling processes need to be simulated in order to optimize fabrication sequences in terms of material distortion capability versus rheological properties of these materials and in terms of grain size with potential impact on ultrasonic inspection performance. In order to verify the process capability, a reduced ¼ scale component of 304L stainless steel primary pipes has been fabricated in a similar forging sequence. Study of the recrystallization aspect at different locations of the component was part of the objectives of the project. The paper gives a view of all combined approaches: theoretical approach by recrystallization modeling as well as simulation of forging and rolling sequences with Forge® software (coupled to a mean-field metallurgical model called Thermide) and fabrication of a reduced scale part with nozzles as a test before the fabrication of the final component

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon

La contraception hormonale féminine (les différentes méthodes, évolution de la législation en France et du rôle du pharmacien d'officine à la vue de la loi HPST)

LYON1-BU Santé (693882101) / SudocSudocFranceF

Indoor Air Quality Campaign in an Occupied Low-Energy House with a High Level of Spatial and Temporal Discretization

International audienceBackground and gaps. The topic of indoor air quality (IAQ) in low-energy buildings has received increasing interest over the past few years. Often based on two measurement points and on passive measurements over one week, IAQ studies are struggling to allow the calculation of pollutants exposure. Objectives. We would like to improve the evaluation of the health impacts, through measurements able to estimate the exposure of the occupants. Methodology. This article presents detailed IAQ measurements taken in an energy-efficient occupied house in France. Two campaigns were conducted in winter and spring. Total volatile organic compounds (TVOC), formaldehyde, the particle numbers and PM2.5, carbon dioxide (CO2), relative humidity (RH), temperature (T), ventilation airflows, and weather conditions were dynamically measured in several points. Laboratory and low-cost devices were used, and an inter-comparison was carried out for them. A survey was conducted to record all the daily activities of the inhabitants. IAQ performance indicators based on the different pollutants were calculated. Results. PM2.5 cumulative exposure did not exceed the threshold available in the literature. Formaldehyde concentrations were high, in the kitchen, where the average concentrations exceeded the threshold. However, the formaldehyde cumulative exposure of the occupants did not exceed the threshold. TVOC concentrations were found to reach the threshold. With these measurements performed with high spatial and temporal discretization, we showed that such detailed data allow for a better-quality health impacts assessment and for a better understanding of the transport of pollutants between rooms

Optimisation d'un mode opératoire de soudage - Identification des paramètres d'une source de chaleur équivalente

International audienceL'utilisation d'un chanfrein étroit pour le soudage de composants lourds tels que ceux utilisés dans l'industrie nucléaire et particulièrement par AREVA, requiert la maîtrise de plusieurs paramètres et plus spécifiquement du retrait. La prediction par la simulation numérique peut alors s'avérer utile pour la définition de modes opératoires de soudage. Le principal objectif de cette etude est d'identifier par méthode inverse les paramètres d'un modèle thermique 3D pour une configuration de soudage MAG multipasse en chanfrein étroit profond sur un acier bas carbone. La simulation de la géométrie des zones fondues ainsi que du champ de temperature dans le metal solide passe par l'optimisation d'un problème multiobjectif. L'optimisation du modèle numérique se base sur des résultats expérimentaux obtenus grace à une instrumentation fine réalisée sur une maquette de soudage. Le modèle de source de chaleur 3D retenu après optimisation est une combinaison de deux sources de chaleur volumiques. Ce modèle peut alors être utilisé comme chargement pour des analyses thermiques, thermo-métallurgiques ou thermo-mécaniques, notamment pour la prédiction des retraits

Identification of a heat source model for multipass narrow groove GMA welding process

International audienceAbstract The use of narrow gap for thick component welding as applied in nuclear industries and especially by AREVA NP, requires the mastering of several parameters and especially shrinkage. The prediction through to numerical simulation is very helpful for welding procedure definition. This paper describes an approach used to determine a 3D heat source dedicated to a new industrial welding process configuration (deep narrow groove multipass lowcarbon steel gas metal arc (GMA) welding, two passes per layer) to assess the groove shrinkage which occurs during welding by numerical simulation. Parameters of this 3D heat source are identified by solving an inverse heat conduction problem by a least square method. A multiobjective optimization is performed with a new proposed metric (Hausdorff distance) in the objective function (sum of square) in order to simulate relevant bead shape and temperatures in the solid zone. Finally, the identified 3D heat source model is a combination of two volumetric heat sources containing five parameters each. It can be used as thermal loading for subsequent thermal metallurgical mechanical calculations

Insulin and hepatic cholestasis during the early post-embryonic development of gilt-head sea bream,

This work is aimed at demonstrating the influence of insulin in the triggering of hepatic cholestasis in young gilt-head sea bream larvae reared under experimental conditions. The results are based on an immunological assay of insulin and an ultrastructural study of the yolk syncytial layer and the liver. Compared to fed larvae, fasting gilt-head sea bream larvae displayed a substantial increase in insulin level correlated with dysfunction of the yolk syncytial layer and hepatic histopathology. This correlation was verified in larvae reared in sea water containing insulin. Ultrastructural observations suggested that insulin affects lipoprotein secretion by the yolk syncytial layer. The failure of plasmatic lipoproteins would then cause dysfunction of the biliary lipid secretion mechanisms and, hence, trigger hepatic cholestasis. These results in gilt-head sea bream show for the first time the influence of insulin in the triggering of hepatic cholestasis during the early development of a vertebrate

Multizone Air Leakage Measurements and Interactions with Ventilation Flows in Low-Energy Homes

International audienceGiven that airtightness is recognized as an essential issue for low-energy dwellings, today it is often included in energy performance (EP) calculations, frequently through single-zone models with uniform air leakage. Because more consideration is often given to EP than to indoor air quality issues, air leakage through internal partitions is often disregarded. Therefore, additional studies are needed to check these assumptions. In the present study air leakage through the building envelope and through internal partitions is investigated. This paper presents the methodology used in an experimental study, conducted to measure multizone air leakages, using the guarded zone pressurization technique. We developed a detailed innovative database with 456 exterior and internal partition wall air leakage measurements, taken in 23 detached houses. For each wall, the database includes general information on the building, special requirements, the building's main characteristics, measurement protocol, type of wall, measurement input data and measurement results (CL, n, q50 and the reliability index developed). Then an analysis of this database is provided. The analysis reveals most important relationships. For instance, internal partition wall air leakage is not related to the envelope's airtightness level; instead, the type of building structure has greater influence. Through this study, we underline the impact on building airflows of more detailed modelling of internal and external air leakage in multizone approaches, with consequences on indoor air quality (IAQ) bedrooms where people spend most of their time. As a conclusion, we propose air leakage values and dispersion input data for multizone IAQ models

Pollutants emission scenarios for residential ventilation performance assessment. A review

International audienc

Development of an assessment methodology for IAQ ventilation performance in residential buildings: An investigation of relevant performance indicators

International audienc