Logiciel SUAVITY : tentative d'objectivation de la beauté d'un bruit

Ce rapport synthétise les travaux ayant conduit à des indicateurs permettant de décrire la "beauté" d'enregistrement de bruits industriels périodiques (machines tournantes) et au logiciel prototype "suavity" correspondant. Les suavités rythmique, tonale et harmonique sont introduites. Elles caractérisent le bruit en terme de régularité rythmique (suavité rythmique), de plaisir auditif des "accords" constituant le signal (suavité tonale) et de la transition entre ces accords (suavité harmonique)

The use of ANSYS to calculate the behaviour of sandwich structures

In this article, we use different models to compute displacements and stresses of a simply supported sandwich beam subjected to a uniform pressure. 8-node quadrilateral elements (Plane 82), multi-layered 8-node quadrilateral shell elements (Shell 91) and multi-layered 20-node cubic elements (Solid 46) are used. The influence of mesh refinement and of the ratio of Young's moduli of the layers are studied. Finally, a local Reissner method is presented and assessed, which permits an improvement in the accuracy of interface stresses for a high ratio of Young's moduli of the layers with Plane 82 elements

Epstein-Barr virus nuclear antigen 1 interacts with regulator of chromosome condensation 1 dynamically throughout the cell cycle

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is a sequence-specific DNA binding protein which plays an essential role in viral episome replication and segregation, by recruiting the cellular complex of DNA replication onto the origin (oriP) and by tethering the viral DNA onto the mitotic chromosomes. Whereas the mechanisms of viral DNA replication are well documented, those involved in tethering EBNA1 to the cellular chromatin are far from being understood. Here, we have identified Regulator of Chromosome Condensation 1 (RCC1) as a novel cellular partner for EBNA1. RCC1 is the major nuclear guanine nucleotide exchange factor (RanGEF) for the small GTPase Ran enzyme. RCC1, associated with chromatin, is involved in the formation of RanGTP gradients critical for nucleo-cytoplasmic transport, mitotic spindle formation, and nuclear envelope reassembly following mitosis. Using several approaches, we have demonstrated a direct interaction between these two proteins and found that the EBNA1 domains responsible for EBNA1 tethering to the mitotic chromosomes are also involved in the interaction with RCC1. The use of an EBNA1 peptide array confirmed the interaction of RCC1 with these regions and also the importance of the N-terminal region of RCC1 in this interaction. Finally, using confocal microscopy and FRET analysis to follow the dynamics of interaction between the two proteins throughout the cell cycle, we have demonstrated that EBNA1 and RCC1 closely associate on the chromosomes during metaphase, suggesting an essential role for the interaction during this phase, perhaps in tethering EBNA1 to mitotic chromosomes

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Introduction of damping in design

International audienceWe start by summarizing noise and vibration problematics.Then available modeling tools are presented: materials and sub-structures, absorption, isolation, damping and encapsulation.Concerning vibrations, emphasis is put on structural damping: decoupling pads, viscous damping, Tuned mass dampers and Non-linear energy sinks. These solutions are compared in terms of pro and cons

Structural damping using nonlinear dampers (NES)

International audienceWe start by summarizing noise and vibration problematics.Then available modeling tools are presented: materials and sub-structures, absorption, isolation, damping and encapsulation.Concerning vibrations, emphasis is put on structural damping: decoupling pads, viscous damping, Tuned mass dampers and Non-linear energy sinks. These solutions are compared in terms of pro and cons

Méthodes d'analyse par éléments finis des contraintes aux interfaces dans les structures sandwich

The goal of this work is to develop finite elements tools allowing to compute sandwich structures without adding any other hypothese than the very general asumption of linear elasticity. Two approaches have been followed in this work. First, we expose how to develop hybrid finite elements, in which stresses at interfaces between the different layers are obtained through Lagrange multipliers. Both 2D and 3D elements, based on the principle of virtual work and on the Pian and Tong functional, are developped and assessed. Then, after having determined the capabilities of the finite element code Ansys 5.3, we propose a post-processing method, based on the Reissner's functional, in order to recover interface stresses from nodal displacements given by displacements elements. Finaly, the two approaches are confronted in order to compare the quality of numerical results but also the confort of use, programming and implementation in existing finite elements codes.Le but de ce travail est de développer des outils par éléments finis permettant de calculer des structures sandwich sans ajouter aucune autre hypothèse que celle, très générale, de l'élasticité linéaire. Deux voies ont été suivies dans ce travail. Tout d'abord, nous exposons comment développer des éléments finis hybrides, dans lesquels les contraintes aux interfaces entre les différentes couches sont obtenues par l'intermédiaire de multiplicateurs de Lagrange. Des éléments 2D et 3D, basés sur le principe du travail virtuel et sur la fonctionnelle de Pian et Tong sont développés et validés. Ensuite, après avoir examiné les possibilités offertes par le code de calcul Ansys 5.3, nous proposons une méthode de post-traitement, basée sur la fonctionnelle de Reissner, permettant de recouvrer les contraintes d'interfaces à partir des déplacements nodaux obtenus à partir des éléments en déplacements. Finalement ces deux approches sont confrontées entre elles, tant sur le plan de la qualité des résultats numériques que sur la facilité d'utilisation, de programmation et d'implémentation dans des codes de calculs existants

Vibration control: designing with/for damping

International audienceTo reduce the vibrations seen by a product, three main families of solutions (physics) exist: to realize a decoupling (decoupling pads), to thermally dissipate energy (viscous damping) or to mechanically capture energy (Tuned mass dampers; Non-linear energy sinks).We will briefly present these different possibilities, their drawbacks and advantages, their scope of use, and the main points entering their dimensioning.Emphasis will be put on viscous damping and NES since experimental results will be presented and compared to simulation