Publications associées à Rotationnel

On the commutativity of flows of rough vector fields

In the class of Sobolev vector fields in R-n of bounded divergence, for which the theory of DiPerna and Lions provides a well defined notion of flow, we characterize the vector fields whose flow commutes in terms of the Lie bracket and of a regularity cond ...

ELSEVIER2022

Locally supported tangential vector, n-vector, and tensor fields

Christopher Brandt

We introduce a construction of subspaces of the spaces of tangential vector, n-vector, and tensor fields on surfaces. The resulting subspaces can be used as the basis of fast approximation algorithms for design and processing problems that involve tangenti ...

2020

Homogenization of Multiscale Eddy Current Problem by Localized Orthogonal Decomposition Method

Xiaotao Ren

A homogenization approach for the solution of multiscale eddy current problem is proposed. The method is based on the subspace decomposition and it involves a coarse space and a nested fine space. The homogenized problem is posed in the coarse space with t ...

Institute of Electrical and Electronics Engineers2019

Sur quelques équations aux dérivées partielles en lien avec le lemme de Poincaré

David Valentin Strütt

In this thesis, we study two distinct problems. The first problem consists of studying the linear system of partial differential equations which consists of taking a k-form, and applying the exterior derivative 'd' to it and add the wedge product with a 1- ...

EPFL2018

Limiting absorption principle and well-posedness for the Helmholtz equation with sign changing coefficients

Hoài-Minh Nguyên

In this paper, we investigate the limiting absorption principle associated to and the well-posedness of the Helmholtz equations with sign changing coefficients which are used to model negative index materials. Using the reflecting technique introduced in [ ...

Elsevier2016

Numerical approach to the parallel gradient operator in tokamak scrape-off layer turbulence simulations and application to the GBS code

Paolo Ricci, Joaquim Loizu Cisquella, Sébastien Jolliet, Federico David Halpern, Fabio Riva, Annamaria Mosetto

This paper presents two discretisation schemes for the parallel gradient operator used in scrape-off layer plasma turbulence simulations. First, a simple model describing the propagation of electrostatic shear-Alfven waves, and retaining the key elements o ...

Elsevier2015

Variational Decomposition of Vector Fields in the Presence of Noise

Michaël Unser, Emrah Bostan, Pouya Dehghani Tafti

We present a variational framework, and an algorithm based on the alternating method of multipliers (ADMM), for the problem of decomposing a vector field into its curl- and divergence-free components (Helmholtz decomposition) in the presence of noise. We p ...

IEEE2013

Approximate Sparsity Pattern Recovery: Information-Theoretic Lower Bounds

Michael Christoph Gastpar

Recovery of the sparsity pattern (or support) of an unknown sparse vector from a small number of noisy linear mea- surements is an important problem in compressed sensing. In this paper, the high-dimensional setting is considered. It is shown that if the m ...

Institute of Electrical and Electronics Engineers2013

Exploitation of a general-coordinate guiding centre code for the redistribution of fast ions in deformed hybrid tokamak equilibria

Jonathan Graves, Wilfred Anthony Cooper, David Pfefferlé

Self-consistent fast ion distributions are usually obtained using a code that solves the guiding-centre equations, with an appropriate fast ion source (e.g. NBI pinis) and sink (e.g. collision operators). Straight field-line coordinate systems, such as Boo ...

Iop Publishing Ltd2012

Near-Field Dynamics of Optical Yagi-Uda Nanoantennas

Klaus Kern, Moritz Esslinger

We present near-field measurements of optical Yagi-Uda nanoantennas that are used in receiving mode. The eigenmode imaging of amplitude and phase by apertureless scanning near-field optical microscopy allows us to investigate the dynamics of the local out- ...

American Chemical Society (ACS)2011