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Multiscale mechanical analysis for biomimetic implant design based on Triply Periodic Minimal Surfaces (TPMS) lattices: Application to partial replacement of femoral bone
No full textInternational audienceMedical implants are a common treatment for orthopedic injuries. Their apparent stiffness can be reduced by using architected internal lattices to match the gradient stiffness of the bone, thereby avoiding postoperative biomechanical problems such as stress shielding. The use of TPMS-based lattice structures with smooth junctions offers the potential to tailor the apparent modulus of an implant while minimizing stress concentration throughout the microstructure. In this study, four TPMS-based unit cells are investigated, namely: Schoen’s Gyroid-like (sheet and skeletal), Schwartz’s Primitive, and Schoen’s IWP topologies. The objective of the investigation is to numerically replace a small region of a femoral bone, hereafter referred to as the area of interest (AoI). Multiscale approach is proposed for the 3D model of the femur. The latter consists of the global model (femur bone) and the local model (TPMS unit cell). The unit cells are selected to satisfy the elastic and mechanical loading requirements and are compared according to the von Mises stress distribution after applying periodic boundary conditions. A statistical analysis is performed and a function factor is proposed to facilitate the comparison. The developed methodology allows the design of customized and patient-specific implants when a large medical database is used due to the varying size and shape of patients’ bones
GTnum IMS DEFI #DEFI - Education aux données - Infographie - Groupe thématique numérique de la Direction du numérique pour l'éducation (Ministère de l'Education Nationale, de l'Enseignement et de la Recherche) 2021-2024
No full textProductions des Groupes thématiques numériques (Direction du numérique pour l'éducation du Ministère de l'Education Nationale, de l'Enseignement et de la Recherche) 2021-2024Infographic on the place of data in school programs, produced as part of the GTnum DEFI (Data for Education, Training, Innovation). This project focuses on the development of data literacy in education and is part of the theme “Data literacy: evolution of skills, educational, pedagogical and ethical issues, perspectives for training” of the Digital Thematic Groups 2021-2024.Infographie sur la place des données dans les programmes scolaires, réalisée dans le cadre du GTnum DEFI (Données pour l'Education, la Formation, l'Innovation). Ce projet porte sur le développement de la littératie des données en éducation et s'inscrit dans la thématique "Littératie des données : évolution des compétences, enjeux éducatifs, pédagogiques et éthiques, perspectives pour la formation" des Groupes Thématiques numériques 2021-2024
A Common Ancestor of PDL, Conjunctive Queries, and Unary Negation First-order
No full textarXiv admin note: text overlap with arXiv:2304.10381We introduce and study UCPDL+, a family of expressive logics rooted in Propositional Dynamic Logic (PDL) with converse (CPDL) and universal modality (UCPDL). In terms of expressive power, UCPDL+ strictly contains PDL extended with intersection and converse (a.k.a. ICPDL), as well as Conjunctive Queries (CQ), Conjunctive Regular Path Queries (CRPQ), or some known extensions thereof (Regular Queries and CQPDL). Further, it is equivalent to the extension of the unary-negation fragment of first-order logic (UNFO) with unary transitive closure, which we denote by UNFO*, which in turn strictly contains a previously studied extension of UNFO with regular expressions known as UNFO^reg. We investigate the expressive power, indistinguishability via bisimulations, satisfiability, and model checking for UCPDL+ and CPDL+. We argue that natural subclasses of CPDL+ can be defined in terms of the tree-width of the underlying graphs of the formulas. We show that the class of CPDL+ formulas of tree-width 2 is equivalent to ICPDL, and that it also coincides with CPDL+ formulas of tree-width 1. However, beyond tree-width 2, incrementing the tree-width strictly increases the expressive power. We characterize the expressive power for every class of fixed tree-width formulas in terms of a bisimulation game with pebbles. Based on this characterization, we show that CPDL+ has a tree-like model property. We prove that the satisfiability problem for UCPDL+ is decidable in 2ExpTime, coinciding with the complexity of ICPDL. As a consequence, the satisfiability problem for UNFO* is shown to be 2ExpTime-complete as well. We also exhibit classes for which satisfiability is reduced to ExpTime. Finally, we establish that the model checking problem for fixed tree-width formulas is in PTime, contrary to the full class CPDL+
Engineering nanostructured electrodes for solid oxide cells (SOCs) via microstructural and electrochemical modelling
No full textInternational audienceThe design optimization of nanostructured-infiltrated electrodes for solid oxide cells was investigated by combining microstructural and electrochemical models. A large dataset of nanostructured electrodes (>70) was synthetically generated through an original approach, which combined validated random field and particle-based frameworks. The electrode microstructural correlations were studied by evaluating the impact of the nanoparticles size and loading on the resulting characteristics of the infiltrated phase (i.e. tortuosity factor, percolating fraction and density of active sites). Eventually, the microstructural properties of selected infiltrated microstructures, holding the highest density of triple phase boundary sites (16-112 μm−2), were used as inputs of a 1D electrochemical model tailored for Ni-YSZ electrodes. The simulated polarization resistances of optimized Ni-infiltrated YSZ backbones resulted to sweep in the 0.012–0.021 Ω⋅cm2 range at 750 °C, thus being considerably lower than the value measured for a classic Ni-YSZ composite cermet, 0.071 Ω⋅cm2. Infiltrated Ni-YSZ composites also resulted to potentially improve the reference electrochemical response, showing polarization resistances in the 0.23–0.32 Ω⋅cm2 range. Nonetheless, the integrated microstructural and electrochemical approach highlighted the crucial importance of the catalyst percolation. Significant performance limitations were evidenced when the percolation of Ni nanoparticles was lower than 50%, due to the insufficient effective transport properties
Worldwide Soundscapes: a synthesis of passive acoustic monitoring across realms
No full textAbstract The urgency for remote, reliable, and scalable biodiversity monitoring amidst mounting human pressures on climate and ecosystems has sparked worldwide interest in Passive Acoustic Monitoring (PAM), but there has been no comprehensive overview of its coverage across realms. We present metadata from 358 datasets recorded since 1991 in and above land and water constituting the first global synthesis of sampling coverage across spatial, temporal, and ecological scales. We compiled summary statistics (sampling locations, deployment schedules, focal taxa, and recording parameters) and used eleven case studies to assess trends in biological, anthropogenic, and geophysical sounds. Terrestrial sampling is spatially denser (42 sites/M·km 2 ) than aquatic sampling (0.2 and 1.3 sites/M·km 2 in oceans and freshwater) with only one subterranean dataset. Although diel and lunar cycles are well-covered in all realms, only marine datasets (65%) comprehensively sample all seasons. Across realms, biological sounds show contrasting diel activity, while declining with distance from the equator and anthropogenic activity. PAM can thus inform phenology, macroecology, and conservation studies, but representation can be improved by widening terrestrial taxonomic breadth, expanding coverage in the high seas, and increasing spatio-temporal replication in freshwater habitats. Overall, PAM shows considerable promise to support global biodiversity monitoring efforts
Les cahiers de doléances de l’Orne et du Finistère (2018-2019). Matérialité des cahiers, conditions d’énonciation et de participation. Note de recherche ANR Gilets jaunes
No full textLa démarche de l'enquête restituée dans cette note de recherche s'inscrit dans la continuité des études sur les doléances à l'échelle départementale. En s'appuyant sur une analyse quantitative des doléances recueillies dans l'Orne et le Finistère, ainsi que sur une enquête qualitative de terrain réalisées dans le cadre d'un stage (ANR GILETSJAUNES), cette note apporte un éclairage sur les conditions de production de ces cahiers ainsi que sur les conditions d'énonciation propres aux contributeurs et contributrices, avec un accent mis sur le rapport des Gilets jaunes à ces cahiers.</div
Les thermes de la colline Sainte-Croix. Nouvelle étude, nouvelles interprétations
No full textInternational audienc
Error-based efficient parameter space partitioning for mesh adaptation and local reduced order models
No full textInternational audienceThe resolution and accuracy of numerical partial differential equation solvers are governed by the mesh density and the order of accuracy of the solver. Anisotropic mesh adaptation combined with a posteriori error estimation is known to be a powerful tool to enhance the efficiency of the solvers. However, in engineering applications involving multiple complex congurations, optimization or uncertainty quantication, generating a single adapted mesh to efficiently capture features of the solutions for all possible choices of the problem parameters (geometry, boundary conditions, etc.) is not feasible. This is particularly true when the solution is very sensitive to the problem parameters and changes in the topology of the solution features (e.g. one vs two shocks) occur for small changes in the computational setting. This paper presents a novel algorithm coupling partitioning the parameter space for efficient parameter clustering and local model order reduction and anisotropic mesh adaptation. The hierarchical partitioning is performed by sampling the parameter space using a full-order model on a relatively coarse mesh. The variance of the physical solutions is reconstructed in the parameter space using proper orthogonal decomposition and Taylor's series to guide each partition's size and shape. Subsequently, the solutions are sampled within the optimal partitions to compute the locally adapted mesh and optimal reduced-order model for each partition. The efficacy of the new algorithm is demonstrated by solving heat conduction with material discontinuity and compressible flow problems.</div
How can biodiversity strategy and action plans incorporate genetic diversity and align with global commitments?
No full textInternational audienceNational, subnational, and supranational entities are creating biodiversity strategy and action plans (BSAPs) to develop concrete commitments and actions to curb biodiversity loss, meet international obligations, and achieve a society in harmony with nature. In light of policymakers’ increasing recognition of genetic diversity in species and ecosystem adaptation and resilience, this article provides an overview of how BSAPs can incorporate species’ genetic diversity. We focus on three areas: setting targets; committing to actions, policies, and programs; and monitoring and reporting. Drawing from 21 recent BSAPs, we provide examples of policies, knowledge, projects, capacity building, and more. We aim to enable and inspire specific and ambitious BSAPs and have put forward 10 key suggestions mapped to the policy cycle. Together, scientists and policymakers can translate high level commitments, such as the Convention on Biological Diversity’s Kunming–Montreal Global Biodiversity Framework, into concrete nationally relevant targets, actions and policies, and monitoring and reporting mechanisms
A multiscale nanodosimetric study of GCR protons and alpha particles in the organs of astronauts on the lunar surface
No full textInternational audienceThe early DNA damage on the surface of the Moon due to GCR protons and alpha particles were assessed using a multiscale approach in Geant4. This consisted of three simulation stages. A periodic boundary conditions approach was used to obtain the radiation field on the surface and inside a proposed lunar habitat. The radiation field on the cellular scale was obtained in the organs of male and female astronauts using the ICRP145 tetrahedral mesh phantoms. This was subsequently simulated using a full human cell model in Geant4-DNA to obtain the early DNA damage. Geant4-DNA track structure ionisation models upper energy limits were extended to be able to model the interactions of the GCR at sub-cellular level, covering an energy range from a few eV up to 1 TeV. Hadronic interactions and the modelling of induced radiochemical species were also implemented. The early DNA damage was assessed using the Geant4-DNA molecularDNA example. A greater yield of DNA damage was observed on the lunar surface compared with the habitat, and indirect damage due to induced hydroxyl radicals constituted most of the damage. This study demonstrates a complete simulation pipeline for the assessment of early DNA damage in astronauts in the space radiation environment