Termination orders for 3-polygraphs

This note presents the first known class of termination orders for 3-polygraphs, together with an application.Comment: 4 pages, 12 figure

Génératrice à aimants permanents à flux axial à grand diamètre avec entrefer immergé

Cette étude propose une méthode de modélisation et de conception adaptée aux machines à flux axial et à Double Stator (poly-entrefer) destinée à être intégrée comme génératrice pour une hydrolienne RIM-DRIVEN de grande puissance. La particularité du concept RIM-DRIVEN ou à entrainement circonférentiel réside dans le fait que la machine électrique se situe sur la périphérie de l’hélice. De plus, dans cette étude, l’entrefer de la machine est considéré immergé dans l’eau de mer. Les particularités du système imposent de mettre au point des modèles de dimensionnement adaptés. Ainsi, un modèle électromagnétique analytique 2D inversé permettant le calcul des dimensions géométriques principales est présenté. De même, un modèle thermique spécifique aux machines à entrefer immergé est décrit. Ces modèles permettent d’estimer la masse et le coût des parties actives. Cette machine à flux axial est comparée en termes de coûts matières, masses et comportement thermique avec une machine à flux radial à aimants permanents dimensionnée pour un même cahier des charges. Il en ressort clairement que la machine à flux axial double stator est thermiquement moins contrainte que les machines à simple stator

Courants porteurs ?

Entre deux congrès et au terme d’une année qui a vu se multiplier les études, s’aiguiser la réflexion sur la fréquentation des bibliothèques, l’état de la lecture publique et celui des BU, il convient de prendre le recul nécessaire afin d’orienter l’action des temps à venir pour aborder au mieux le grand tournant de la bibliothèque hybride

Courants dynamiques pluripolaires

We show the existence of birational self-maps f of P^k which are algebraically stable with algebraic degree d, for which there is a unique positive closed (1,1) current T satisfying f^*T=d T and ||T||=1 and for which the current T gives total mass to a pluripolar set

Regularization of currents and entropy

Let T be a positive closed (p,p)-current of mass 1 on a compact Kahler manifold X. Then, there exist a constant c, independent of T, and smooth positive closed (p,p)-currents Tn and Sn of mass c such that Tn-Sn converge weakly to T. We also extend this result to positive pluriharmonic currents. Then we study the wedge product of positive closed (1,1)-currents having continuous potential with positive pluriharmonic currents. As an application, we give an estimate of the topological entropy of meromorphic maps on compact Kahler manifolds.Comment: 17 pages, to appear in Ann. Sci. Ecol. Norm. Su

Erosion and deposition in interplain channels of the Maury channel system

Large turbidity currents originating on the insular margin of southern lceland have flowed clown a 2 500 km-long pathway comprising rise valleys, unchanneled plains and segments of erosional and depositional deep-sea channels that are collectively called the Maury Channel system. Two steep interplain reaches of the channel have been eut up to 100 m through volcanogenic turbidites of probable La te Pleistocene age. Near-bottom observations with side-scan sonars and profllers across the upper channels (at 59°24\u27N, 18°50\u27W, 2 750 m depth) and at the lower interplain channel (around 56°23\u27N, 24°25\u27W, 3 340 m depth) defmed their structure and morphology. The upper channels, and a tributary to the lower channel, start as broad, shallow depressions that deepen and narrow downstream. The lower channel bas a pattern of anastomosing branches that probably evolved by head ward extension of low-angle tribu taries to the original sinuous channel, and its branches are at different stages of development. Several hundred bottom photographs show well-indurated rocks on channel walls and floors, with such flysch-like characteristics as cyclic graded bedding, clastic dikes, and syndepositional deformation. The lower-channel branches have been eut by turbidity currents with speeds of 5- 12 rn/sec., and combined discharges exceeding 1 x 106 m3 /sec. Bedrock erosion in and around the channels bas proceeded by intense corrasion and fluid stressing, and is marked by such small-scale effects as rock polishing, fluting, pot-holing and ledge recession. Rockfalls have caused retreat of steep channel walls, and conglomerate or pcbbly mudstone deposits suggest that debris flows have been locally active. Sorne coarse debris delivered by these processes and clay halls torn from semi-lithifled outcrops remain in the channels, but the channel f1ll is generally thin, with a patch y veneer of pelagie mud that bas accumulated since the last major turbidity current event. The surfaces of the unconsolidated s~diment have been smoothed and lineated, or moulded into seo ur moats and occasional fields of ripples, by thermohaline currents