HAL Université de Toulouse, et Toulouse INP
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Liquid drop impact on granular beds: the influence of drop inertia and grain size
No full textInternational audienceDroplet impact on granular beds shows two crater regimes set by splash appearance. The influence of grain diameter is unified by a new dimensionless number, capturing inertial dissipation through grain contacts
Low-dimensional modelling of viscous fluids in porous media over curvilinear surfaces
No full textInternational audienceWe present a theoretical framework for porous media gravity currents propagating over rigid curvilinear surfaces. By reducing the flow dynamics to low-dimensional models applicable on surfaces where curvature effects are negligible, we demonstrate that, for finite-volume releases, the flow behaviour in both two-dimensional and axisymmetric configurations is primarily governed by the ratio of the released viscous fluid volume to the characteristic volume of the curvilinear surface. Our theoretical predictions are validated using computational fluid dynamics simulations based on a sharp-interface model for macroscopic flow in porous media. In the context of carbon dioxide geological sequestration, our findings suggest that wavy cap rock geometries can enhance trapping capacity compared with traditional flat-surface assumptions, highlighting the importance of incorporating realistic topographic features into subsurface flow models
Numeric study on solar-driven pyrolysis of plastic waste
No full textInternational audiencePyrolysis is a technology that converts plastics into fuel or chemicals at high temperatures, offering significant advantages over other plastic waste disposal methods. Currently, the energy required for plastic pyrolysis usually comes directly or indirectly from fossil fuels, thus causing carbon emissions. This study investigates a plastic pyrolysis method using solar energy as the heat source, aiming to reduce carbon emissions and achieve carbon neutrality. A numerical model was developed to investigate temperature distribution, reaction rates, yields, and energy utilization in plastic pyrolysis. Simulation results indicated that under certain conditions, the plastic conversion exceeded 73%, with an energy efficiency above 17.3%. Heat flux, structural parameters of porous medium and inlet parameters of plastic are the key factors affecting the plastic pyrolysis. Heat flux had a significant impact on the system performance, plastic conversion remained below 30% when heat flux was below 0.3 MW/m2. Structural parameters of porous medium affected the reaction through both temperature and heat transfer process, which made their impact more complex. Reducing the plastic inlet speed and increasing the temperature can improve the plastic conversion and increase the proportion of oil and gas components in the product
The MMX InfraRed Spectrometer (MIRS) for the spectral characterization of the Martian system
No full textInternational audienceMIRS (MMX InfraRed Spectrometer) is a push-broom imaging spectrometer onboard of the JAXA sample return MMX mission. It has been built by the French laboratory LESIA, today LIRA (Laboratory for Instrumentation and Research in Astrophysics) of Paris Observatory-PSL in collaboration with five other French laboratories, collaboration and financial support of CNES and close collaboration with JAXA and MELCO. MIRS, designed to accomplish the MMX scientific objectives, has been built to be adapted on MMX Exploration Module. MIRS will remotely observe the Martian system for three years. MIRS will observe Phobos, Deimos and Mars in the spectral range 0.9-3.6 µm to characterize surface composition of the satellites and investigate Martian atmospheric variations
Numerical simulation and optimization of ballistic protection structures
No full textInternational audienceTraditional passive systems for ballistics mainly involve the use of heavy materials. For example, we have: High-hardness steels, reinforced aluminium alloys, and ceramics. A traditional approach cannot consider all the issues related to ballistic protection. Hence, we developed a few ballistics functions that can describe the performance of passive systems. Some of these have already been considered in the previous study, such as: projectile destabilisation, erosion, and kinetic energy absorption.Studies in this field have shown that different materials can stop projectiles differently; therefore, we can highlight the ballistic limit velocity as a parameter when evaluating the effectiveness of a protection system. The traditional approach is experience-based. We resort to the opposite process:Based on numerical simulations and optimisation, we propose a virtual material that can meet these functions and then compare the results with experimental data. We defined a simplified model by means of ABAQUS Commercial Code representing the impact of a NATO 7,62 AP Projectile on a monolayer aluminium tile; we identified and approximated the parameters imposing Johnson-Cook Plasticity and Damage simplified laws. Then impose a constraint on the Plastic Work. We performed the simulation for an initial velocity, extracted the residual velocity of the projectile and performed the average. By means of an optimisation plugin called Simulia ISIGHT. We defined a calibration to find the terms for the reference simulation by respecting the constraint on the plastic work.Les systèmes passifs balistiques traditionnels font principalement appel à des matériaux lourds, tels que les aciers à haute dureté, les alliages d'aluminium renforcés et les céramiques. Cette approche traditionnelle ne permet pas de prendre en compte l'ensemble des aspects liés à la protection balistique. C'est pourquoi nous avons développé plusieurs fonctions balistiques capables de décrire les performances des systèmes passifs. Certaines d'entre elles ont déjà été étudiées, notamment la déstabilisation du projectile, l'érosion et l'absorption de l'énergie cinétique.Des études dans ce domaine ont montré que différents matériaux peuvent arrêter les projectiles différemment ; par conséquent, la vitesse limite balistique peut être considérée comme un paramètre important pour évaluer l'efficacité d'un système de protection. L'approche traditionnelle est empirique. Nous avons opté pour une démarche inverse :À partir de simulations numériques et d'optimisations, nous proposons un matériau virtuel capable de remplir ces fonctions, puis nous comparons les résultats avec des données expérimentales. Nous avons défini un modèle simplifié à l'aide du logiciel commercial ABAQUS, représentant l'impact d'un projectile perforant OTAN de 7,62 mm sur une plaque d'aluminium monocouche ; nous avons identifié et approché les paramètres en imposant les lois simplifiées de plasticité et d'endommagement de Johnson-Cook. Nous avons ensuite imposé une contrainte sur le travail plastique. La simulation a été réalisée pour une vitesse initiale, la vitesse résiduelle du projectile a été extraite et la moyenne a été calculée à l'aide du plugin d'optimisation Simulia ISIGHT. Un étalonnage a été défini afin de déterminer les termes de la simulation de référence, en respectant la contrainte sur le travail plastique.I sistemi passivi tradizionali per la balistica prevedono principalmente l'uso di materiali pesanti. Ad esempio, disponiamo di: acciai ad alta durezza, leghe di alluminio rinforzate e ceramiche. Un approccio tradizionale non può considerare tutte le problematiche relative alla protezione balistica. Pertanto, abbiamo sviluppato alcune funzioni balistiche in grado di descrivere le prestazioni dei sistemi passivi. Alcune di queste sono già state considerate nello studio precedente, come: destabilizzazione del proiettile, erosione e assorbimento di energia cinetica.Studi in questo campo hanno dimostrato che materiali diversi possono arrestare i proiettili in modo diverso; pertanto, possiamo evidenziare la velocità limite balistica come parametro nella valutazione dell'efficacia di un sistema di protezione. L'approccio tradizionale si basa sull'esperienza. Noi ricorriamo al processo opposto:Sulla base di simulazioni numeriche e ottimizzazioni, proponiamo un materiale virtuale in grado di soddisfare queste funzioni e confrontiamo i risultati con i dati sperimentali. Abbiamo definito un modello semplificato tramite il codice commerciale ABAQUS che rappresenta l'impatto di un proiettile NATO 7,62 AP su una piastra monostrato di alluminio; Abbiamo identificato e approssimato i parametri che impongono le leggi semplificate di Plasticità e Danno di Johnson-Cook. Quindi abbiamo imposto un vincolo sul Lavoro Plastico. Abbiamo eseguito la simulazione per una velocità iniziale, estratto la velocità residua del proiettile ed eseguito la media. Utilizzando un plugin di ottimizzazione chiamato Simulia ISIGHT, abbiamo definito una calibrazione per trovare i termini per la simulazione di riferimento rispettando il vincolo sul lavoro plastico
Deleterious consequences of metal-peptide interactions in Alzheimer's Disease and counteracting approaches
No full textInternational audienc
Agriculture, aquaculture and fishing: impact of food standards on biodiversity. Summary of the scientific report of the study
No full textThe 2021 French Climate and Resilience Act introduced an Eco-labelling display on food products to inform consumers of the environmental cost of their purchases. The construction of this eco-labelling scheme has given rise to significant methodological work with stakeholders. An interim assessment highlighted the difficulty of capturing all the dimensions of biodiversity. With this in mind, the Ministries of Ecological Transition and Agriculture and Food, along with ADEME, called on INRAE and Ifremer in 2022 to better document this biodiversity component, focusing on production practices. In order to inform public policy more widely, the public authorities have chosen to rely on voluntary standards that require the certification of practices. The development of these voluntary standards are also at the heart of many debates on the relationship between sustainable production and consumption. The study, entitled «BiodivLabel», was carried out by a multidisciplinary committee of scientific experts from public research and higher education organizations
Transmission of DNA methylation: genetic or epigenetic ? A transgenerational case study in quails
No full textInternational audiencePart of the environmental story of individuals lies within their DNA methylation (DNAm). Variations in the environment can trigger changes at the DNAm level and translate to phenotypic variability, even in the progeny of the individuals directly impacted. However, the amount of environmental information transmitted between generations via epigenetic phenomena is hardly quantifiable. The present study analyses DNAm from Reduced Representation Bisulfite Sequencing (RRBS) data for 1267 quails (Coturnix japonica) within 3 successive generations following an environmental modification. Among 112,561 dinucleotides CG (CpG) used, we estimated an average heritability of DNAm of 0.24. After a sub-selection of 40 CpG sites showing high heritability and a significant difference in methylation between two epilines, we conducted methylation Quantitative Trait Loci (metQTL) analysis at those sites in order to shed light on the origin of the high heritability of those sites: genetic or epigenetic
Risk-controlling Prediction with Distributionally Robust Optimization
No full textInternational audienceConformal prediction is a popular paradigm to quantify the uncertainty of a model's output on a new batch of data. Quite differently, distributionally robust optimization aims at training a model that is robust to uncertainties in the distribution of the training data. In this paper, we examine the links between the two approaches. In particular, we show that we can learn conformal prediction intervals by distributionally robust optimization on a well chosen objective. This further entails to train a model and build conformal prediction intervals all at once, using the same data
