Recent Developments in Radical Photoinitiator Chemistry

Radiation curing is an established technology used in many industrial manufacturing processes. New applications and technical specifications stimulate the continuous development of tailor-made photoinitiators which can efficiently meet specific requirements. A new class of radical photoinitiators, bisacylphosphine oxides (BAPO), give four initiating radicals per photoinitiator molecule and undergo photo-bleaching of the low-energy absorption band. These features make the compounds highly efficient for radiation curing of highly opaque white pigmented systems, thick coatings, or fiber-reinforced formulations

PACE Solver Description: DreyFVS

We describe DreyFVS, a heuristic for Directed Feedback Vertex Set submitted to the 2022 edition of Parameterized Algorithms and Computational Experiments Challenge. The Directed Feedback Vertex Set problem asks to remove a minimal number of vertices from a digraph such that the resulting digraph is acyclic. Our algorithm first performs a guess on a reduced instance by leveraging the Sinkhorn-Knopp algorithm, to then improve this solution by pipelining two local search methods

Champs de repères 2D non orthogonaux

National audience

Frame Fields for CAD models

International audienceGiven a triangulated surface, a unit length tangent vector field can be used to orient entities located on the surface, such as glyphs or strokes. When these entities are invariant under a π/2 rotation (squares, or curvature hatching), the orientation can be represented by a frame field i.e. four orthogonal tangent unit vectors at each point of the surface. The generation of such fields is a key component of recent quad meshing algorithms based on global parameterization, as it defines the orientation of the final facets. State-of-the-art methods are able to generate smooth frame fields subject to some hard constraints (direction and topology) or smooth constraints (matching the curvature direction). When we have a surface triangular mesh, and a vector defined on each facet, we can't directly know if all the vectors are colinear. We first have to define the (so called) parallel transport of every edge to compare the vectors on a common plan. When dealing with CAD models, the field must be aligned with feature edges. A problem occurs when there is a low angle corner formed by two colliding feature edges. Our solution not only defines the parallel transport to obtain smoothed frame fields on a surface triangular mesh, it also redefines the parallel transport wherever there is a low angle corner, to smooth a frame field as if these corners' angles were π/2

Designing 2D and 3D Non-Orthogonal Frame Fields

International audienceWe present a method for direction field design on surface and volumetric meshes supporting non-orthogonality. Our approach is a generalization of the representation of 3D cross fields in spherical harmonic basis. As such it induces a geometrically meaningful measure of smoothness, allows orthogonality control by a simple parameter and enables orientation constraints of a single direction. To the best of our knowledge this is the first work to propose non-orthogonal 3D frame field design. We demonstrate the applicability of our method to generate anisotropic quadrangular and hexahedral meshes which are particularly useful for remeshing CAD models

α-Synuclein in central nervous system and from erythrocytes, mammalian cells, and Escherichia coli exists predominantly as disordered monomer

Since the discovery and isolation of α-synuclein (α-syn) from human brains, it has been widely accepted that it exists as an intrinsically disordered monomeric protein. Two recent studies suggested that α-syn produced in Escherichia coli or isolated from mammalian cells and red blood cells exists predominantly as a tetramer that is rich in α-helical structure (Bartels, T., Choi, J. G., and Selkoe, D. J. (2011) Nature 477, 107-110; Wang, W., Perovic, I., Chittuluru, J., Kaganovich, A., Nguyen, L. T. T., Liao, J., Auclair, J. R., Johnson, D., Landeru, A., Simorellis, A. K., Ju, S., Cookson, M. R., Asturias, F. J., Agar, J. N., Webb, B. N., Kang, C., Ringe, D., Petsko, G. A., Pochapsky, T. C., and Hoang, Q. Q. (2011) Proc. Natl. Acad. Sci. 108, 17797-17802). However, it remains unknown whether or not this putative tetramer is the main physiological form of α-syn in the brain. In this study, we investigated the oligomeric state of α-syn in mouse, rat, and human brains. To assess the conformational and oligomeric state of native α-syn in complex mixtures, we generated α-syn standards of known quaternary structure and conformational properties and compared the behavior of endogenously expressed α-syn to these standards using native and denaturing gel electrophoresis techniques, size-exclusion chromatography, and an oligomer-specific ELISA. Our findings demonstrate that both human and rodent α-syn expressed in the central nervous system exist predominantly as an unfolded monomer. Similar results were observed when human α-syn was expressed in mouse and rat brains as well as mammalian cell lines (HEK293, HeLa, and SH-SY5Y). Furthermore, we show that α-syn expressed in E. coli and purified under denaturing or nondenaturing conditions, whether as a free protein or as a fusion construct with GST, is monomeric and adopts a disordered conformation after GST removal. These results do not rule out the possibility that α-syn becomes structured upon interaction with other proteins and/or biological membranes

Génération de maillages hexaédriques pour des simulations de grandes déformations

This thesis focuses on the development of hexahedral meshing methods suitable for large deformation simulations in non-linear mechanics. Domain parameterization methods based on frame fields are used to generate high-quality hexahedral meshes aligned with the domain boundaries. However, during large deformations, the mesh quality may degrade and potentially block the simulation. This thesis explores the idea of determining an optimal connectivity for the mesh elements while taking into account the anticipated deformations.In 2D, a complete pipeline is developed to tackle this challenge by combining previous work and scientific contributions. In 3D, contributions are made to approach this objective, particularly by controlling the boundary valences of hexahedral meshes produced from frame fields. The different parts of the thesis address the steps of large deformation numerical simulations, the advantages of global parameterization methods, the results of simulations on industrial 2D meshes, and contributions to improving the flexibility and robustness of the hexahedral meshing process.The ultimate goal is to reduce the time spent by engineers in generating an adequate mesh for a simulation by considering a priori information on the deformation to which the mesh and the object will be subjected.Cette thèse se concentre sur le développement de méthodes de maillage hexaédrique adaptées aux simulations de grandes déformations en mécanique non-linéaire. Les méthodes de paramétrisation du domaine basées sur les champs de repère sont utilisées pour générer des maillages hexaédriques de haute qualité alignés sur les bords du domaine. Cependant, lors de grandes déformations, la qualité du maillage peut se dégrader et potentiellement bloquer la simulation. Cette thèse explore l'idée de déterminer une connectivité optimale pour les éléments du maillage en tenant compte des déformations prévues. En 2D, un pipeline complet est développé pour réaliser ce défi en combinant des travaux antérieurs et des contributions scientifiques. En 3D, des contributions sont apportées pour se rapprocher de cet objectif, notamment en contrôlant les valences de bord des maillages hexaédriques produits à partir de champs de repère. Les différentes parties de la thèse abordent les étapes de la simulation numérique de grandes déformations, les avantages des méthodes de paramétrisation globale, les résultats de simulations sur des maillages industriels 2D, ainsi que des contributions pour améliorer la flexibilité et la robustesse du processus de maillage hexaédrique. L'objectif final est de réduire le temps passé par les ingénieurs à générer un maillage adéquat pour une simulation en prenant en compte des informations a priori sur la déformation à laquelle le maillage et l'objet seront soumis

Génération de maillages hexaédriques pour des simulations de grandes déformations

This thesis focuses on the development of hexahedral meshing methods suitable for large deformation simulations in non-linear mechanics. Domain parameterization methods based on frame fields are used to generate high-quality hexahedral meshes aligned with the domain boundaries. However, during large deformations, the mesh quality may degrade and potentially block the simulation. This thesis explores the idea of determining an optimal connectivity for the mesh elements while taking into account the anticipated deformations.In 2D, a complete pipeline is developed to tackle this challenge by combining previous work and scientific contributions. In 3D, contributions are made to approach this objective, particularly by controlling the boundary valences of hexahedral meshes produced from frame fields. The different parts of the thesis address the steps of large deformation numerical simulations, the advantages of global parameterization methods, the results of simulations on industrial 2D meshes, and contributions to improving the flexibility and robustness of the hexahedral meshing process.The ultimate goal is to reduce the time spent by engineers in generating an adequate mesh for a simulation by considering a priori information on the deformation to which the mesh and the object will be subjected.Cette thèse se concentre sur le développement de méthodes de maillage hexaédrique adaptées aux simulations de grandes déformations en mécanique non-linéaire. Les méthodes de paramétrisation du domaine basées sur les champs de repère sont utilisées pour générer des maillages hexaédriques de haute qualité alignés sur les bords du domaine. Cependant, lors de grandes déformations, la qualité du maillage peut se dégrader et potentiellement bloquer la simulation. Cette thèse explore l'idée de déterminer une connectivité optimale pour les éléments du maillage en tenant compte des déformations prévues. En 2D, un pipeline complet est développé pour réaliser ce défi en combinant des travaux antérieurs et des contributions scientifiques. En 3D, des contributions sont apportées pour se rapprocher de cet objectif, notamment en contrôlant les valences de bord des maillages hexaédriques produits à partir de champs de repère. Les différentes parties de la thèse abordent les étapes de la simulation numérique de grandes déformations, les avantages des méthodes de paramétrisation globale, les résultats de simulations sur des maillages industriels 2D, ainsi que des contributions pour améliorer la flexibilité et la robustesse du processus de maillage hexaédrique. L'objectif final est de réduire le temps passé par les ingénieurs à générer un maillage adéquat pour une simulation en prenant en compte des informations a priori sur la déformation à laquelle le maillage et l'objet seront soumis

Generation of hexahedral meshes for large deformation simulations

Cette thèse se concentre sur le développement de méthodes de maillage hexaédrique adaptées aux simulations de grandes déformations en mécanique non-linéaire. Les méthodes de paramétrisation du domaine basées sur les champs de repère sont utilisées pour générer des maillages hexaédriques de haute qualité alignés sur les bords du domaine. Cependant, lors de grandes déformations, la qualité du maillage peut se dégrader et potentiellement bloquer la simulation. Cette thèse explore l'idée de déterminer une connectivité optimale pour les éléments du maillage en tenant compte des déformations prévues. En 2D, un pipeline complet est développé pour réaliser ce défi en combinant des travaux antérieurs et des contributions scientifiques. En 3D, des contributions sont apportées pour se rapprocher de cet objectif, notamment en contrôlant les valences de bord des maillages hexaédriques produits à partir de champs de repère. Les différentes parties de la thèse abordent les étapes de la simulation numérique de grandes déformations, les avantages des méthodes de paramétrisation globale, les résultats de simulations sur des maillages industriels 2D, ainsi que des contributions pour améliorer la flexibilité et la robustesse du processus de maillage hexaédrique. L'objectif final est de réduire le temps passé par les ingénieurs à générer un maillage adéquat pour une simulation en prenant en compte des informations a priori sur la déformation à laquelle le maillage et l'objet seront soumis.This thesis focuses on the development of hexahedral meshing methods suitable for large deformation simulations in non-linear mechanics. Domain parameterization methods based on frame fields are used to generate high-quality hexahedral meshes aligned with the domain boundaries. However, during large deformations, the mesh quality may degrade and potentially block the simulation. This thesis explores the idea of determining an optimal connectivity for the mesh elements while taking into account the anticipated deformations.In 2D, a complete pipeline is developed to tackle this challenge by combining previous work and scientific contributions. In 3D, contributions are made to approach this objective, particularly by controlling the boundary valences of hexahedral meshes produced from frame fields. The different parts of the thesis address the steps of large deformation numerical simulations, the advantages of global parameterization methods, the results of simulations on industrial 2D meshes, and contributions to improving the flexibility and robustness of the hexahedral meshing process.The ultimate goal is to reduce the time spent by engineers in generating an adequate mesh for a simulation by considering a priori information on the deformation to which the mesh and the object will be subjected

Quad Mesh Quantization Without a T‐Mesh

International audienceAbstract Grid preserving maps of triangulated surfaces were introduced for quad meshing because the 2D unit grid in such maps corresponds to a sub‐division of the surface into quad‐shaped charts. These maps can be obtained by solving a mixed integer optimization problem: Real variables define the geometry of the charts and integer variables define the combinatorial structure of the decomposition. To make this optimization problem tractable, a common strategy is to ignore integer constraints at first, then to enforce them in a so‐called quantization step. Actual quantization algorithms exploit the geometric interpretation of integer variables to solve an equivalent problem: They consider that the final quad mesh is a sub‐division of a T‐mesh embedded in the surface, and optimize the number of sub‐divisions for each edge of this T‐mesh. We propose to operate on a decimated version of the original surface instead of the T‐mesh. It is easier to implement and to adapt to constraints such as free boundaries, complex feature curves network etc