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Concevoir des LMS capacitants : une démarche pédagogique et ergonomique
No full textInternational audienc
Investigation of asymmetric heating in Poiseuille-Rayleigh-Bénard water flow: A numerical study
No full textInternational audienceIn this paper, a numerical investigation of the impact of asymmetric heating on laminar mixed convection in Poiseuille-Rayleigh-Bénard water flow within parallel horizontal channels is presented. The study has been carried out in a rectangular channel with a transverse aspect ratio of 10, and considered both low (Ra = 1.28 × 10^4) and high (Ra = 1.4 × 10^5) Rayleigh numbers, with Reynolds numbers of 50 and 100. A uniform heat flux was applied to the top and bottom walls of the heated region to assess its effect on the system's thermoconvective behavior and heat transfer efficiency. Two flux ratio scenarios were considered: qt/qb = 1 and qt/qb = 2.The results indicate that increasing the flux ratio intensifies the destabilizing temperature gradient and significantly enhances buoyancy-induced flow, thereby influencing the patterns of thermoconvective structures. Specifically, flux ratios lead to an increased number of plumes originating from the bottom of the channel, while reducing their height and confining them between the bottom wall and the upper thermal boundary layer. It is also observed that flux ratios do not affect the mechanisms involved in the formation of longitudinal rolls. Furthermore, at low Rayleigh numbers, asymmetric heating has a pronounced impact on the establishment length. In contrast, this effect diminishes and becomes negligible at higher Rayleigh numbers. Numerical computations further reveal that near the bottom wall, the Nusselt number exhibits singular behavior, approaching infinity. Regardless of Reynolds and Rayleigh numbers, flux ratios significantly enhance heat transfer within the system. Additionally, near the top wall, the buoyancy effects from the bottom wall have negligible impact on heat transfer, except in the case where qt/qb = 2, Re = 50 and Ra = 1.4 × 10^5, where instability in the upper thermal layer was observed
Open-Source Framework for Modeling the Evolution of Fiber Orientation
No full textInternational audienceModeling fiber orientation plays a crucial rule in predicting the behaviour of fiber reinforced thermoplastic materials. The equation that governs the evolution of the fiber orientation is hyperbolic in nature and requires handling fourth-order tensors, which are currently unavailable in OpenFOAM® .The current work explores the possibility of using OpenFOAM® and symbolic computation for modeling the evolution of fiber orientation. For this purpose, a functionObject was programmed to work as a plug-in solver for any OpenFOAM® incompressible flow solver, with the ability to compute the evolution of the second-order orientation tensor in a decoupled manner. Several fiber orientation models and closure relations available in the literature were implemented in the tool, which were verified by comparing their predictions with independent results obtained by numerically integrating the associated governing equations
Spark Plasma Sintered manganese substituted strontium M-type nanohexaferrite
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Annulation d'une condamnation de 4,7 milliards de dollars contre NFL
No full textBrève de jurisprudence américaine postée sur le site de l'IDE
Photogrammetric processing of MSL images: a case study at the Mont Mercou outcrop in Gale crater on Mars
No full textInternational audienceThe Curiosity Mars rover spent more than 70 sols to investigate the Mont Mercou outcrop in Gale crater in 2021 [1], capturing a unique set of image data with wide spatial coverage and high overlap. This allowed us to create a high resolution 3D Digital Outcrop Model (DOM) using 6825 images from the rover's Mastcam and Navcam instruments with a Structure from Motion (SfM) process. This process is often difficult and time intensive, so we developed a new Python-based pre-processing pipeline to make the creation of large DOMs more straightforward
Improvement of gas barrier properties of chitosan-based composite coatings under humid conditions through palmitic acid grafting
No full textInternational audienceThe chemical grafting of palmitic acid (PA) on chitosan (CS) was performed through the coupling reaction of the carboxyl group of PA with the amine groups of CS in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Fourier Transform InfraRed (FTIR), Differential Scanning Calorimetry (DSC) and 13 C NMR spectroscopies were used to analyze the synthesized chitosan-grafted-palmitic acid (CS-g-PA). Acidified aqueous solutions of CS, a mix of CS and PA (CS/PA) and CS-g-PA (1 wt%), in the presence of different contents of vermiculite (VMT), have been coated on 130 µm thick corona-treated PET films with thicknesses ranging from 1 to 3 µm. Gas permeability of the PET coated films were determined under dry conditions and under different relative humidity ratios. The grafted CS exhibited a higher hydrophobicity which resulted in a fewer loss of barrier properties in humid conditions.</div
Associations of Global Burden of Diseases study-derived dietary scores with mortality and chronic disease risk: a comprehensive analysis from the prospective NutriNet-Santé study
No full textInternational audienceThe Global Burden of Diseases (GBD) network has proposed theoretical minimum risk exposure level (TMREL) for leading risk factors associated with diet that minimize the risk of morbimortality from chronic diseases. TMREL can be applied to develop follow-up or evaluation indicators in individual studies. The validity of these scores can be tested by assessing associations with health outcomes in prospective cohorts. In this study conducted within the NutriNet-Santé cohort, four dietary scores (TMREL-Risk Score, TMREL-Probability of adequacy, TMREL-standardized distance, and TMREL dietary score) using different scoring methods were developed, with higher scores reflecting less healthy diets. Associations of these scores with the risk of type 2 diabetes, cancer, cardiovascular diseases (CVD) and mortality were estimated using multivariable Cox proportional hazards models, adjusted for a wide range of covariates. Counterfactual and marginal structural models were used to infer causality. Analyses were conducted in a sample of up to103,324 participants (78.3% women, mean age of 43.6 years old (y) (SD=14.6)), followed for a median of 8.47 (IQR=14.7) years (2009-2024). The association with dietary scores (for 1SD-increase) varied in magnitude for each health outcome. For mortality, HR varied from 1.12 (95%CI =1.07-1.18, ) to 1.18 (95%CI =1.12-1.24) for TMRELStdis and TMREL-DI, for overall cancer from 1.07 (95%CI =1.03-1.12) to 1.09 (1.04-1.13) for TMREL-RS and TMREL-PA, for CVD from 1.07 (95%CI =1.00-1.16) to 1.12 (95%CI =1.04-1.20) for TMREL-PA and TMREL-RS, and for type 2 diabetes from 1.33 (95%CI =1.23-1.43) to 1.47 (95%CI =1.36-1.59) for TMREL-DI and TMREL-PA. Marginal structural Cox models strengthened all associations compared to classical analyses. Standardized survival curves showed clear associations, especially for the risk of cancer and type 2 diabetes. Dietary scores based on GBD TMREL can serve as key indicators for characterizing diet quality in relation to long-term health, and using different scoring systems helped evaluate the robustness of these associations
Abandoning the Car to Embrace the Bicycle in Urban France: A Model of Modal Shift for Daily Commuting Routines
No full textInternational audienceThe current climate context is prompting a reconsideration of transportation modes, with the bicycle offering significant benefits, including reduced emissions, noise pollution, and urban congestion and improved public health. Despite policies encouraging cycling, many urban French citizens struggle to adopt it. Rather than focusing on barriers, this study examines individuals who have reduced or abandoned car use in favor of cycling in urban areas. The study describes the modal shift process of 20 individuals from four cities in France, with diverse socio-economic backgrounds and ages. Through semi-structured, biographical interviews, key stages in the transition are identified: predispositions, triggering factors, exploration and trial, and long-term appropriation. The article also explores situations where cyclists revert to car use for specific trips. Findings reveal favorable conditions for cycling but also highlight challenges, offering insights that could influence urban planning policies in France