L'espace communal, essai de modélisation

La modélisation spatiale appliquée à un espace communal (Châtillon, Hauts-de- Seine) permet d'identifier un secteur sensible qui nécessiterait un aménagement spécifique

Periodic System Approximation for Operational Modal Analysis of Operating Wind Turbine

International audienceThe inherent modelling of the operational wind turbines and rotating machines do not agree in general with the assumptions of the operational modal analysis (OMA) methods developed for civil engineering, where time invariant systems are considered. Current OMA methods for rotating machines introduce datapre-processing to adapt classical identification methods. However, they show strong limitations and rely on strong assumptions, such as the isotropy of the rotor, making them hardly applicable in practice. To overcome these limitations, this paper proposes to employ the Floquet theory of periodic system to approximate rotating systems as time invariant systems. Thus, classical identification methods can be used to retrieve the parametric signature of the periodic systems. This Floquet-based approximation gives a physical meaning to the identified eigenmodes. The proposed approach is validated on both a small numerical model and an aero-servo-elastic numerical model of a rotating 10MW wind turbine, with isotropic and anisotropic rotors, using the stochastic subspace identification to retrieve the modes and their uncertainty

Détection d'anisotropie d'un rotor d'éolienne par suivi du changement de phase des modes propres

National audienceFault detection by modal analysis is a highly developed field in civil engineering. Despite the rotation of the blades, it is possible to apply it and develop similar approaches for wind turbines using a Fourier modeling of the eigenmodes. A loss of isotropy for the rotor can be the consequence of a defect in the angle of attack (pitch) of the blades, of the accumulation of ice or else the presence of structural defects resulting in a loss of stiffness on one or more blades. The monitoring of this effect using the deformations of the estimated modes is validated with an example where a global drop in stiffness of 5% of a rotor blade is simulated.La détection de défaut par analyse modale est un domaine très développé dans le génie civil. Malgré la rotation des pales, il est possible de l'appliquer et de développer des approches similaires pour les éoliennes en utilisant une modélisation des modes propres en base de Fourier. Une perte d'isotropie du rotor peut être la conséquence d'un défaut d'angle d'attaque (pitch) des pales, de l'accumulation de glace ou bien de la présence de défauts structurels entraînant une perte de raideur sur une ou plusieurs pales. La surveillance de ce phénomène à partir des déformées des modes estimés est validée avec un exemple où une baisse globale de raideur de 5% d'une pale du rotor est simulée

Mode shape phase change detection in wind turbine under anisotropy variation

International audienceFault detection by modal analysis is a highly developed field in civil engineering. For wind turbines, a loss of isotropy for the rotor can be the consequence of a defect in the angle of attack (pitch) of the blades, or the accumulation of ice, or else the presence of structural defects resulting in a loss of stiffness on one or more blades. It is highly desirable to apply classical OMA techniques, and this despite the rotation of the blades. It is shown in this paper that it is possible to apply LTI approaches on wind turbines similarly to the methodology usually applied to standard civil engineering structures using an approximate Fourier modeling of the eigenmodes. The monitoring of anisotropy using the mode shapes of the estimated modes is validated with an example where a global loss of stiffness of 5% of a rotor blade is simulated

The Yin-Yang of the Green Fluorescent Protein:Impact on Saccharomyces cerevisiae stress resistance

International audienceAlthough fluorescent proteins are widely used as biomarkers (Yin), no study focuses on their influence on the microbial stress response. Here, the Green Fluorescent Protein (GFP) was fused to two proteins of interest in Saccharomyces cerevisiae. Pab1p and Sur7p, respectively involved in stress granules structure and in Can1 membrane domains. These were chosen since questions remain regarding the understanding of the behavior of S. cerevisiae facing different heat kinetics or oxidative stresses. The main results showed that Pab1p-GFP fluorescent mutant displayed a higher resistance than that of the wild type under a heat shock. Moreover, fluorescent mutants exposed to oxidative stresses displayed changes in the cultivability compared to the wild type strain. In silico approaches showed that the presence of the GFP did not influence the structure and so the functionality of the tagged proteins meaning that changes in yeast resistance were certainly related to GFP ROS-scavenging ability (Yang)

L'espace communal, essai de modélisation

Die shematische Darstellung einer Gemeinde ermöglicht, einen problematischen Sektor zu erkennen, der eines spezifischen Ausbaus bedürfte (Châtillon, Hauts-de-Seine).</jats:p

L'espace communal, essai de modélisation

Die shematische Darstellung einer Gemeinde ermöglicht, einen problematischen Sektor zu erkennen, der eines spezifischen Ausbaus bedürfte (Châtillon, Hauts-de-Seine).Spatial modelization applied to a commune (Châtillon, Hauts-de-Seine) makes it possible to identify a sensitive area in need of specific development.La modélisation spatiale appliquée à un espace communal (Châtillon, Hauts-de-Seine) permet d’identifier un secteur sensible qui nécessiterait un aménagement spécifique.Denimal Laurent. L'espace communal, essai de modélisation. In: Mappemonde, 1990/1. pp. 35-37

Mode shape phase change detection in wind turbine under anisotropy variation

International audienceFault detection by modal analysis is a highly developed field in civil engineering. For wind turbines, a loss of isotropy for the rotor can be the consequence of a defect in the angle of attack (pitch) of the blades, or the accumulation of ice, or else the presence of structural defects resulting in a loss of stiffness on one or more blades. It is highly desirable to apply classical OMA techniques, and this despite the rotation of the blades. It is shown in this paper that it is possible to apply LTI approaches on wind turbines similarly to the methodology usually applied to standard civil engineering structures using an approximate Fourier modeling of the eigenmodes. The monitoring of anisotropy using the mode shapes of the estimated modes is validated with an example where a global loss of stiffness of 5% of a rotor blade is simulated