École normale supérieure de Cachan

About: École normale supérieure de Cachan is a education organization based out in Cachan, Île-de-France, France. It is known for research contribution in the topics: Decidability & Finite element method. The organization has 2717 authors who have published 5585 publications receiving 175925 citations.

Asymptotic preserving schemes for the Klein---Gordon equation in the non-relativistic limit regime

Abstract: We consider the Klein---Gordon equation in the non-relativistic limit regime, i.e. the speed of light $$c$$ c tending to infinity. We construct an asymptotic expansion for the solution with respect to the small parameter depending on the inverse of the square of the speed of light. As the first terms of this asymptotic can easily be simulated our approach allows us to construct numerical algorithms that are robust with respect to the large parameter $$c$$ c producing high oscillations in the exact solution.

Wine Reputation and Quality Controls: The Origin of the AOCs in 19th Century France

Abstract: Even though they were officially settled during the second half of the 1930s, the AOCs (Appelations d'origine controlee) constitute the outcome of a long process that took place over the 19 th century and that reached its apogee between 1905 (the date of adoption of the law on fraud and falsification) and 1914. This article studies the pre-history of the AOCs in order to elucidate in which circumstances collective marks are required, that is, when neither the market alone nor the individual marks provide efficient information on the quality of goods. Historical experience confirms the theoretical conclusion that economic agents try to bind a mark to a territory in order to enjoy a rent. However, before 1905, a halt to this ambition came much less from the ex-ante law than from its judicial interpretations. But unlike theoretical predictions, rules and procedures are much less surrogates than complements while the recourse to a framework law (loi cadre) rather than to a law or to a decree is not necessarily synonymous with decentralization.

Towards unconditional soundness: computationally complete symbolic attacker

Abstract: We consider the question of the adequacy of symbolic models versus computational models for the verification of security protocols We neither try to include properties in the symbolic model that reflect the properties of the computational primitives nor add computational requirements that enforce the soundness of the symbolic model We propose in this paper a different approach: everything is possible in the symbolic model, unless it contradicts a computational assumption In this way, we obtain unconditional soundness almost by construction And we do not need to assume the absence of dynamic corruption or the absence of key-cycles, which are examples of hypotheses that are always used in related works We set the basic framework, for arbitrary cryptographic primitives and arbitrary protocols, however for trace security properties only

Hybrid Excitation Synchronous Machines: Energy Efficient Solution for Vehicle Propulsion

Abstract: In this paper the suitability of a class of electric machines for vehicle traction application is discussed. These machines, known as hybrid excitation synchronous machines, combine a permanent magnet excitation with wound field excitation. The goal behind the principle of hybrid excitation is to combine advantages of PM excited machines and wound field synchronous machines. It is shown that these machines have good flux weakening capability compared to PM machines, and that they constitute an energy efficient solution for vehicles propulsion.