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

Comparison between the fundamental group scheme of a relative scheme and that of its generic fiber

We show that the natural morphism $\phi:\pi_1(X_{\eta},x_{\eta})\to \pi_1(X,x)_{\eta}$ between the fundamental group scheme of the generic fiber $X_{\eta}$ of a scheme $X$ over a connected Dedekind scheme and the generic fiber of the fundamental group scheme of $X$ is always faithfully flat. As an application we give a necessary and sufficient condition for a finite, dominated pointed $G$-torsor over $X_{\eta}$ to be extended over $X$. We finally provide examples where $\phi:\pi_1(X_{\eta},x_{\eta})\to \pi_1(X,x)_{\eta}$ is an isomorphism..Comment: 19 pages, final versio

A decomposition theorem for smoothable varieties with trivial canonical class

In this paper we show that any smoothable complex projective variety, smooth in codimension two, with klt singularities and numerically trivial canonical class admits a finite cover, \'etale in codimension one, that decomposes as a product of an abelian variety, and singular analogues of irreducible Calabi-Yau and irreducible symplectic varieties.Comment: 21 page

A Simpson Correspondence for Abelian Varieties in Positive Characteristic

Let X/C be a smooth projective variety over the complex numbers. In the early 90's, Simpson established an equivalence between the category of local systems and that of the semi-stable Higgs bundles whose Chern class is zero. The correspondence between Higgs bundles and local systems can be viewed as a Hodge theorem for nonabelian cohomology. The theory is hence called the non-abelian Hodge theory, and sometimes is called the Simpson correspondence. It has been a while to search for such a correspondence in positive characteristic. In this article, the following result is shown. Let X be an abelian variety over an algebraically closed field k of characteristic p > 0. Let X' be its Frobenius twist. Fix a natural number r, and consider the moduli stack (Higgs') of Higgs bundles on X' of rank r and the moduli stack (LocSys) of local systems on X of rank r. Then there are maps from (LocSys) and (Higgs') to a common base scheme B', which is an affine space over k. Moreover, there exists an étale surjective map U to B', such that after a base change to U, the two stacks (Higgs') and (LocSys) are isomorphic. This result partially generalizes a previous result of Groechenig, where X is a curve, to higher dimensional varieties

Not More of the Same: Michel Serres’s Challenge to the Ethics of Alterity

Much French philosophy of the late twentieth and early twenty-first centuries has been marked by the positive valorization of alterity, an ethical position that has recently received a vigorous assault from Alain Badiou’s privilege of sameness. This article argues that Badiou shares a great deal in common with the philosophies of alterity from which he seeks to distance himself, and that Michel Serres’s little-known account of alterity offers a much more radical alternative to the ethics of difference. Drawing on both translated and as yet untranslated works, I argue that the Serresian ontology of inclination, along with his conceptual personae of the hermaphrodite and the parasite, informs ethical and political positions that offer a distinctive ethics and politics that present fresh insights about the relation between the singular and the universal, the contingency of market exchange, and the nature of violence