Search results for "fluid"
showing 10 items of 5513 documents
Noise removal using a nonlinear two-dimensional diffusion network
1998
Un reseau electrique non lineaire bidimensionnel, constitue de N×N cellules identiques, et modelisant l’equation de Nagumo discrete est presente. A l’aide d’une nouvelle description de la fonction non lineaire, on peut predire analytiquement l’evolution temporelle de la partie coherente du signal, ainsi que celle des perturbations de petites amplitudes qui lui sont superposees. Enfin, des applications a l’amelioration du rapport signal sur bruit, ou au traitement d’images sont suggerees.
Global dynamical behaviors in a physical shallow water system
2016
International audience; The theory of bifurcations of dynamical systems is used to investigate the behavior of travelling wave solutions in an entire family of shallow water wave equations. This family is obtained by a perturbative asymptotic expansion for unidirectional shallow water waves. According to the parameters of the system, this family can lead to different sets of known equations such as Camassa-Holm, Korteweg-de Vries, Degasperis and Procesi and several other dispersive equations of the third order. Looking for possible travelling wave solutions, we show that different phase orbits in some regions of parametric planes are similar to those obtained with the model of the pressure …
The tennis racket effect in a three-dimensional rigid body
2017
We propose a complete theoretical description of the tennis racket effect, which occurs in the free rotation of a three-dimensional rigid body. This effect is characterized by a flip ($\pi$- rotation) of the head of the racket when a full ($2\pi$) rotation around the unstable inertia axis is considered. We describe the asymptotics of the phenomenon and conclude about the robustness of this effect with respect to the values of the moments of inertia and the initial conditions of the dynamics. This shows the generality of this geometric property which can be found in a variety of rigid bodies. A simple analytical formula is derived to estimate the twisting effect in the general case. Differen…
Shaken Snow Globes: Kinematic Tracers of the Multiphase Condensation Cascade in Massive Galaxies, Groups, and Clusters
2018
We propose a novel method to constrain turbulence and bulk motions in massive galaxies, groups and clusters, exploring both simulations and observations. As emerged in the recent picture of the top-down multiphase condensation, the hot gaseous halos are tightly linked to all other phases in terms of cospatiality and thermodynamics. While hot halos (10^7 K) are perturbed by subsonic turbulence, warm (10^4 K) ionized and neutral filaments condense out of the turbulent eddies. The peaks condense into cold molecular clouds (< 100 K) raining in the core via chaotic cold accretion (CCA). We show all phases are tightly linked via the ensemble (wide-aperture) velocity dispersion along the line o…
A flux based conservation approach for acoustic problems
2008
International audience
Galerkin and control-volume FEMs evaluation for acoustic problems
2004
International audience
Analyse de la dispersion de la solution MVCEF pour l'équation de Helmholtz
2006
Implementation of single-qubit quantum gates by adiabatic passage and static laser phases
2006
International audience; We propose and analyse experimentally feasible implementations of single-qubit quantum gates based on stimulated Raman adiabatic passage (STIRAP) between magnetic sublevels in atoms coupled by elliptically polarized pulsed laser fields, in part based on a proposal by Kis and Renzoni [Z. Kis, F. Renzoni, Phys. Rev. A 65 (2002) 032318]. These techniques require only the control of the relative phase of the driving fields but do not involve any dynamical or geometric phases, which makes it independent of the other interaction details: detuning, pulse shapes, pulse areas and pulse durations. The suggested techniques are immune to spontaneous emission since the qubit mani…
Controle de l'orientation et de l'alignement moléculaire par un train d'impulsions soudaines
2005
Les recents progres technologiques dans le domaine des Lasers permettent d'envisager le controle de nombreux processus quantiques jouant un role dans une variete de problemes s'etendant de la reactivite chimique a l'information quantique. Dans ce contexte, nous nous sommes interesses au controle de l'orientation ou de l'alignement moleculaire en utilisant un train d'impulsions soudaines. Nous avons defini des etats cibles qui maximisent a la fois l'orientation ou l'alignement et sa duree dans le temps et montre comment atteindre ces etats a l'aide de strategie systematique ou optimisee.
Localization of the tannin-binding site on the salivary PRP IB5
2014
Localization of the tannin-binding site on the salivary PRP IB5. 10. European Symposium on Saliva