1,253 research outputs found
"Barber pole turbulence" in large aspect ratio Taylor-Couette flow
Investigations of counter-rotating Taylor-Couette flow (TCF) in the narrow
gap limit are conducted in a very large aspect ratio apparatus. The phase
diagram is presented and compared to that obtained by Andereck et al. The
spiral turbulence regime is studied by varying both internal and external
Reynolds numbers. Spiral turbulence is shown to emerge from the fully turbulent
regime via a continuous transition appearing first as a modulated turbulent
state, which eventually relaxes locally to the laminar flow. The connection
with the intermittent regimes of the plane Couette flow (pCf) is discussed
Ondes hydrothermales non-linéaires dans un disque et un anneau
URL: http://www-spht.cea.fr/articles/S98/109Nous nous intéressons à la convection thermocapillaire, produite par l'imposition d'un gradient {\it horizontal} de température sur une mince couche de fluide avec surface libre. En géométrie bidimensionnelle nous observons deux modes différents en compétition, tandis qu'en géométrie bidimensionnelle avec conditions limites périodiques, nous étudions la transition à la turbulence d'une onde propagative homogÚne
Brissarthe â Le Bourg
En 1985, le suivi des travaux dâadduction dâeau rĂ©alisĂ©s dans le bourg de Brissarthe avait permis de dĂ©limiter la nĂ©cropole mĂ©rovingienne. Une nouvelle tranche de travaux allait permettre de complĂ©ter les donnĂ©es concernant celle-ci, grossiĂšrement centrĂ©e sur lâĂ©glise (mentionnĂ©e en dur dĂšs 866), de 150 m (nord-sud) sur 100 m (est-ouest) ; un autre groupe de sĂ©pultures Ă 120 m de lâĂ©glise semble appartenir Ă un ensemble diffĂ©rent. Un des sept coffres examinĂ©s a livrĂ© une chaĂźnette, deux bague..
Effective radius of ground- and excited-state positronium in collisions with hard walls
We determine effective collisional radii of positronium (Ps) by considering
Ps states in hard-wall spherical cavities. -spline basis sets of electron
and positron states inside the cavity are used to construct the states of Ps.
Accurate Ps energy eigenvalues are obtained by extrapolation with respect to
the numbers of partial waves and radial states included in the bases.
Comparison of the extrapolated energies with those of a pointlike particle
provides values of the effective radius of Ps() in collisions
with a hard wall. We show that for , , and states of Ps, the
effective radius decreases with the increasing Ps center-of-mass momentum, and
find a.u., a.u., and a.u. in
the zero-momentum limit.Comment: 13 pages, 11 figures, submitted to Physical Review
On the decay of turbulence in plane Couette flow
The decay of turbulent and laminar oblique bands in the lower transitional
range of plane Couette flow is studied by means of direct numerical simulations
of the Navier--Stokes equations. We consider systems that are extended enough
for several bands to exist, thanks to mild wall-normal under-resolution
considered as a consistent and well-validated modelling strategy. We point out
a two-stage process involving the rupture of a band followed by a slow
regression of the fragments left. Previous approaches to turbulence decay in
wall-bounded flows making use of the chaotic transient paradigm are
reinterpreted within a spatiotemporal perspective in terms of large deviations
of an underlying stochastic process.Comment: ETC13 Conference Proceedings, 6 pages, 5 figure
Finding instabilities in the community structure of complex networks
The problem of finding clusters in complex networks has been extensively
studied by mathematicians, computer scientists and, more recently, by
physicists. Many of the existing algorithms partition a network into clear
clusters, without overlap. We here introduce a method to identify the nodes
lying ``between clusters'' and that allows for a general measure of the
stability of the clusters. This is done by adding noise over the weights of the
edges of the network. Our method can in principle be applied with any
clustering algorithm, provided that it works on weighted networks. We present
several applications on real-world networks using the Markov Clustering
Algorithm (MCL).Comment: 4 pages, 5 figure
Extension of charge-state-distribution calculations for ion-solid collisions towards low velocities and many-electron ions
Knowledge of the detailed evolution of the whole charge-state distribution of projectile ions colliding with targets is required in several fields of research such as material science and atomic and nuclear physics but also in accelerator physics, and in particular in regard to the several foreseen large-scale facilities. However, there is a lack of data for collisions in the nonperturbative energy domain and that involve many-electron projectiles. Starting from the etacha model we developed [Rozet, Nucl. Instrum. Methods Phys. Res., Sect. B 107, 67 (1996)10.1016/0168-583X(95)00800-4], we present an extension of its validity domain towards lower velocities and larger distortions. Moreover, the system of rate equations is able to take into account ions with up to 60 orbital states of electrons. The computed data from the different new versions of the etacha code are compared to some test collision systems. The improvements made are clearly illustrated by 28.9MeVu-1Pb56+ ions, and laser-generated carbon ion beams of 0.045 to 0.5MeVu-1, passing through carbon or aluminum targets, respectively. Hence, those new developments can efficiently sustain the experimental programs that are currently in progress on the "next-generation" accelerators or laser facilities.Fil: Lamour, E.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Fainstein, Pablo Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Centro AtĂłmico Bariloche; ArgentinaFil: Galassi, Mariel Elisa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; ArgentinaFil: Prigent, C.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Ramirez, C. A.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; ArgentinaFil: Rivarola, Roberto Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de FĂsica de Rosario. Universidad Nacional de Rosario. Instituto de FĂsica de Rosario; ArgentinaFil: Rozet, J. P.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Trassinelli, M.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; FranciaFil: Vernhet, D.. Centre National de la Recherche Scientifique; Francia. Universite de Paris; Franci
Characterisation of the Prion Protein Oligomerisation by Md Simulations and Small Angle X-Ray Scattering
Transient growth in Taylor-Couette flow
Transient growth due to non-normality is investigated for the Taylor-Couette
problem with counter-rotating cylinders as a function of aspect ratio eta and
Reynolds number Re. For all Re < 500, transient growth is enhanced by
curvature, i.e. is greater for eta < 1 than for eta = 1, the plane Couette
limit. For fixed Re < 130 it is found that the greatest transient growth is
achieved for eta between the Taylor-Couette linear stability boundary, if it
exists, and one, while for Re > 130 the greatest transient growth is achieved
for eta on the linear stability boundary. Transient growth is shown to be
approximately 20% higher near the linear stability boundary at Re = 310, eta =
0.986 than at Re = 310, eta = 1, near the threshold observed for transition in
plane Couette flow. The energy in the optimal inputs is primarily meridional;
that in the optimal outputs is primarily azimuthal. Pseudospectra are
calculated for two contrasting cases. For large curvature, eta = 0.5, the
pseudospectra adhere more closely to the spectrum than in a narrow gap case,
eta = 0.99
Huysmans pornographe
La question de lâĂ©criture pornographique est dâautant plus intĂ©ressante chez Huysmans que, au-delĂ du tĂ©moignage quâelle offre quant Ă la place de lâĂ©rotisme dans la littĂ©rature de la fin du dix-neuviĂšme siĂšcle, elle est Ă©galement un critĂ©rium inattendu de lâunitĂ© de lâĆuvre. En effet, si la pornographie est au cĆur des pratiques sexuelles et littĂ©raires huysmansiennes, câest moins sa visibilitĂ© explicite qui est Ă souligner que sa surprenante discrĂ©tion dans les romans naturalistes qui ont pourtant fait la rĂ©putation sulfureuse de lâauteur.
Tout au contraire, ce sont les poĂšmes du Drageoir aux Ă©pices qui donnent les portraits de femmes annonciateurs de ce que lâon retrouvera sous la plume de lâauteur dâĂ rebours, ambivalents et marquĂ©s par le caractĂšre antithĂ©tique de lâamour sadique, par la mĂȘme cruditĂ© pornographique que celle des fleurs de Des Esseintes ou le rĂȘve de la Syphilis. Le monde onirique ouvre alors lâespace dâune spiritualisation de lâordure qui est celui du sadisme de FĂ©licien Rops ou de Gilles de Rais, qui transfigure lâĂ©criture du sexe en Ă©criture de la monstruositĂ© et les noces de la chair en noces spirituelles.
Mais le trait le plus marquant est certainement celui de la rĂ©flexion sur lâessence mĂȘme de lâĂ©criture que la question permet Ă lâauteur converti. AprĂšs sâĂȘtre plu Ă provoquer le bourgeois, Huysmans sâemploie en effet Ă scandaliser les bigots par le mĂȘme langage, faisant basculer le point dâĂ©quilibre de sa pornographie de pornĂȘ Ă graphĂȘ.
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