Cambrian Hopf Algebras

Cambrian trees are oriented and labeled trees which fulfill local conditions around each node generalizing the conditions for classical binary search trees. Based on the bijective correspondence between signed permutations and leveled Cambrian trees, we define the Cambrian Hopf algebra generalizing J.-L. Loday and M. Ronco's algebra on binary trees. We describe combinatorially the products and coproducts of both the Cambrian algebra and its dual in terms of operations on Cambrian trees. We also define multiplicative bases of the Cambrian algebra and study structural and combinatorial properties of their indecomposable elements. Finally, we extend to the Cambrian setting different algebras connected to binary trees, in particular S. Law and N. Reading's Baxter Hopf algebra on quadrangulations and S. Giraudo's equivalent Hopf algebra on twin binary trees, and F. Chapoton's Hopf algebra on all faces of the associahedron.Comment: 60 pages, 43 figures. Version 2: New Part 3 on Schr\"oder Cambrian Algebra. The title change reflects this modificatio

A Monolithic Finite Element Approach to Compute Permeabilityatc Microscopic Scales in LCM Processes

International audienceIn this paper, a numerical approach for permeability determination at the mesoscopic and microscopic scales is proposed. In an eulerian framework, the computational domain (corresponding to the elementary cell) is composed of one single mesh, where the interface between the fibres (microscopic scale) or the yarns composing the fabric (mesoscopic scale) and fluid is captured through a level set approach. At the microscopic scale, Stokes equations are considered. At the mesoscopic scale, resolution of a coupled Stokes (in the fluid)Darcy (in the yarn) flow is necessary and is performed using also a mixed finite element technique, providing a single system of equations. Stabilization of the Brinkman flow is attained using the P1+/P1 element. Results on permeability computation at the microscopic scale, as well as sensitivity analysis, illustrate the methodology followed

Etudes numériques et expérimentales sur les suspensions de fibres et de sphères solides

International audienceUne méthode numérique a été développé afin de permettre le calcul du mouvement de particules solides dans un fluide en cisaillement. Les calculs sur un volume élémentaire permettent d'étudier l'évolution de l'orientation de particules allongées pour un fluide chargés en particules sphériques. Finalement, des observations expérimentales sont faites en utilisant des outils de rhéooptique

Numerical and Experimental Studies of Suspensions of Fiber and Spherical Solid Particles

Coupled Problems 2009 is one of the Thematic Conferences of the European Community in Computational Methods in Applied Sciences (ECCOMAS).International audienceThis paper is devoted the behavior of suspension of fiber-spheres particles. We pointed out by experimental and numerical observations that the Jeferry approximation is no more valid as the sphere particle concentration increases

IGUANe: a 3D generalizable CycleGAN for multicenter harmonization of brain MR images

In MRI studies, the aggregation of imaging data from multiple acquisition sites enhances sample size but may introduce site-related variabilities that hinder consistency in subsequent analyses. Deep learning methods for image translation have emerged as a solution for harmonizing MR images across sites. In this study, we introduce IGUANe (Image Generation with Unified Adversarial Networks), an original 3D model that leverages the strengths of domain translation and straightforward application of style transfer methods for multicenter brain MR image harmonization. IGUANe extends CycleGAN architecture by integrating an arbitrary number of domains for training through a many-to-one strategy. During inference, the model can be applied to any image, even from an unknown acquisition site, making it a universal generator for harmonization. Trained on a dataset comprising T1-weighted images from 11 different scanners, IGUANe was evaluated on data from unseen sites. The assessments included the transformation of MR images with traveling subjects, the preservation of pairwise distances between MR images within domains, the evolution of volumetric patterns related to age and Alzheimer$^\prime$s disease (AD), and the performance in age regression and patient classification tasks. Comparisons with other harmonization and normalization methods suggest that IGUANe better preserves individual information in MR images and is more suitable for maintaining and reinforcing variabilities related to age and AD. Future studies may further assess IGUANe in other multicenter contexts, either using the same model or retraining it for applications to different image modalities.Comment: 23 pages, 8 figures; typos correcte

Optical extinction in a single layer of nanorods

We demonstrate that almost 100 % of incident photons can interact with a monolayer of scatterers in a symmetrical environment. Nearly-perfect optical extinction through free-standing transparent nanorod arrays has been measured. The sharp spectral opacity window, in the form of a characteristic Fano resonance, arises from the coherent multiple scattering in the array. In addition, we show that nanorods made of absorbing material exhibit a 25-fold absorption enhancement per unit volume compared to unstructured thin film. These results open new perspectives for light management in high-Q, low volume dielectric nanostructures, with potential applications in optical systems, spectroscopy, and optomechanics

Comment rater la validation de votre algorithme d'ordonnancement

National audienceImaginons que vous veniez de développer un nouvel algorithme d’ordonnancement : félicitations ! Pourdisposer d’informations qualitatives sur votre algorithme et le comparer à d’autres vous avez décidécomme beaucoup avant vous de réaliser des simulations. Très classiquement vos simulations portentsur des jeux de données aléatoires (ici, des graphes orientés acycliques)

Semiconductor nanostructures for spectral filtering

International audienceWe present theoretical and experimental study of nanostructured guided-mode resonant filter, made of a highly doped InAsSb grating and a GaSb waveguide