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Concept

Perturbation atmosphérique

Publications associées (10)

Emergence of representative signals for sudden stratospheric warmings beyond current predictable lead times

Guillaume Romain Obozinski, Raphaël Gérard Théodore Michel Marie de Deloÿe et Fourcade de Fondeville

Major sudden stratospheric warmings (SSWs) are extreme wintertime circulation events of the Arctic stratosphere that are accompanied by a breakdown of the polar vortex and are considered an important source of predictability of tropospheric weather on subs ...

Copernicus Gesellschaft Mbh2021

Stability of standing waves for a nonlinear Klein-Gordon equation with delta potentials

François Samer Genoud

In this paper, we study local well-posedness and orbital stability of standing waves for a singularly perturbed one-dimensional nonlinear Klein-Gordon equation. We first establish local well-posedness of the Cauchy problem by a fixed point argument. Unlike ...

2019

Transposition of Francis turbine cavitation compliance at partial load to different operating conditions

François Avellan, Arthur Tristan Favrel, Christian Landry, Joao Gomes Pereira Junior

Francis turbines operating in part load conditions experience a swirling flow at the runner outlet leading to the development of a precessing cavitation vortex rope in the draft tube. This cavitation vortex rope changes drastically the velocity of pressure ...

2017

On the stability of travelling waves with vorticity obtained by minimization

Boris Buffoni

We modify the approach of Burton and Toland Comm. Pure Appl. Math. LXIV. 975-1007 (2011) to show the existence of periodic surface water waves with vorticity in order that it becomes suited to a stability analysis. This is achieved by enlarging the functio ...

Springer Basel2013

Study on room modal equalization at low frequencies with electroacoustic absorbers

Hervé Lissek, Romain Boulandet, Etienne Thierry Jean-Luc Rivet, Iris Rigas

Nowadays, requirements for acoustic treatments in rooms are ever more demanding in terms of performance and compactness. A recurring issue in closed spaces is the occurrence of standing waves and acoustic interferences at low frequencies. These unwanted ph ...

2012

Existence and orbital stability of standing waves for some nonlinear Schrodinger equations, perturbation of a model case

François Samer Genoud

The following nonlinear Schrodinger equation is studied ...

2009

Existence And Stability Of High Frequency Standing Waves For A Nonlinear Schrodinger Equation

François Samer Genoud

This article is concerned with the existence and orbital stability of standing waves for a nonlinear Schrodinger equation (NLS) with a nonautonomous nonlinearity. It continues and concludes the series of papers [6, 7, 8]. In [6], the authors make use of a ...

2009

Lectures on the Orbital Stability of Standing Waves and Application to the Nonlinear Schrodinger Equation

Charles Stuart

In the first part of these notes, we deal with first order Hamiltonian systems in the form Ju'(t) = del H(u(t)) where the phase space X may be in infinite dimensional so as to accommodate some partial differential equations. The Hamiltonian H is an element ...

Birkhäuser-Verlag, Springer2008

Théorie de bifurcation et de stabilité pour une équation de Schrödinger avec une non-linéarité compacte

François Samer Genoud

The nonlinear Schrödinger equation i∂tw + Δw +V(x)|w|p-1w = 0 w = w(t,x) : Ι × RN → C, N ≥ 2, (1) is studied, with p > 1, V : RN \ {0} → R and Ι ⊂ R an interval. The coefficient V is subject to various hypotheses. In particular, it is always assumed ...

EPFL2008

Rotor-Stator Interaction Induced Pressure Fluctuations: CFD and Hydroacoustic Simulations in the Stationary Components of a Multistage Centrifugal Pump

François Avellan, Mohamed Farhat, Philippe Dupont

In a centrifugal pump the interaction between the rotating impeller pressure field and the stationary diffuser pressure field yields pressure fluctuations as the result of a modulation process. These fluctuations may induce hydroacoustic pressure fluctuati ...

2007