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Concept

Phénomène de Gibbs

Publications associées (17)

An optimal preconditioned FFT-accelerated finite element solver for homogenization

Till Junge, Ali Falsafi

We generalize and provide a linear algebra-based perspective on a finite element (FE) ho-mogenization scheme, pioneered by Schneider et al. (2017)[1] and Leuschner and Fritzen (2018)[2]. The efficiency of the scheme is based on a preconditioned, well-scale ...

ELSEVIER SCIENCE INC2023

Elimination of ringing artifacts by finite-element projection in FFT-based homogenization

Till Junge, Ali Falsafi

Micromechanical homogenization is often carried out with Fourier-accelerated methods that are prone to ringing artifacts. We here generalize the compatibility projection introduced by Vond.rejc et al. (2014) [24] beyond the Fourier basis. In particular, we ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2022

Laser photo-detachment combined with Langmuir probe in magnetized electronegative plasma: how the probe size affects the plasma dynamic?

Ivo Furno, Riccardo Agnello

Laser photo-detachment combined with a Langmuir probe (LP) is used to diagnose negative ion properties in electronegative plasmas. The technique relies on the combined use of a laser pulse and an LP. The laser pulse converts negative ions into electron-ato ...

2021

Controlling oscillations in high-order Discontinuous Galerkin schemes using artificial viscosity tuned by neural networks

Jan Sickmann Hesthaven, Deep Ray, Niccolo' Discacciati

High-order numerical solvers for conservation laws suffer from Gibbs phenomenon close to discontinuities, leading to spurious oscillations and a detrimental effect on the solution accuracy. A possible strategy to reduce it comprises adding a suitable amoun ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2020

Dynamic Modeling and Control of a Coupled Reforming/Combustor System for the Production of H2 via Hydrocarbon-Based Fuels

Theodoros Damartzis

The present work aims to provide insights into the dynamic operation of a coupled reformer/combustion unit that can utilize a variety of saturated hydrocarbons (HCs) with 1–4 C atoms towards H2 production (along with CO2). Within this concept, a preselecte ...

2020

Controlling oscillations in spectral schemes using Artificial Neural Networks

Lukas Schwander

Global Fourier spectral methods are excellent tools to solve conserva- tion laws. They enable fast convergence rates and highly accurate solutions. However, being high-order methods, they suffer from the Gibbs phenomenon, which leads to spurious numerical ...

2020

No time for drifting: Comparing performance and applicability of signal detrending algorithms for real-time fMRI

Dimitri Nestor Alice Van De Ville, Frank Scharnowski, Yury Koush, Rotem Roza Kopel

As a consequence of recent technological advances in the field of functional magnetic resonance imaging (fMRI), results can now be made available in real-time. This allows for novel applications such as online quality assurance of the acquisition, intra-op ...

2019

Combined Experimental-Numerical Analysis of Transient Phenomena in a Photoelectrochemical Water Splitting Cell

Sophia Haussener, Mikaël Dumortier

A combined experimental-numerical approach was used to study transient phenomena occurring in a photoelectrochemical cell using a membrane-separated porous TiO2-based photoanode and a dark Pt-based cathode. The effects of three parameters (pH in the anodic ...

American Chemical Society2016

A Spectral Method for Generating Surrogate Graph Signals

Dimitri Nestor Alice Van De Ville, Elvira Pirondini, Martina Coscia

The increasing availability of network data is leading to a growing interest in processing of signals on graphs. One notable tool for extending conventional signal-processing operations to networks is the graph Fourier transform that can be obtained as the ...

IEEE Institute of Electrical and Electronics Engineers2016

Upgrade of a 30 kV/10 mA anode power supply for triode type gyrotron

Stefano Alberti, Jean-Philippe Hogge, Damien Fasel, Ugo Siravo, Jérémie Dubray, Philippe Marmillod, Albert Perez, Blaise Marlétaz

The RF power of a gyrotron with a triode type magnetron-injection-gun (MIG) can be directly controlled via the voltage applied between its anode and its cathode. Hence, the performance of this type of gyrotron relies directly on the possibilities offered b ...

Elsevier Science Sa2015

Duration of Purkinje cell complex spikes increases with their firing frequency

Michele Giugliano

Climbing fiber (CF) triggered complex spikes (CS) are massive depolarization bursts in the cerebellar Purkinje cell (PC), showing several high frequency spikelet components (+/- 600 Hz). Since its early observations, the CS is known to vary in shape. In th ...

Frontiers Research Foundation2015

Numerical approximation of the fractional Laplacian via hp-finite elements, with an application to image denoising

Jan Sickmann Hesthaven, Paolo Gatto

The fractional Laplacian operator (−∆)s on a bounded domain Ω can be realized as a Dirichlet-to-Neumann map for a degenerate elliptic equation posed in the semi-infinite cylinder Ω × (0,∞). In fact, the Neumann trace on Ω involves a Muckenhoupt weight that ...

Springer Verlag2015

An 8-PPM, 45 pJ/bit UWB Transmitter with Reduced Number of PA Elements

Yusuf Leblebici, Alexandre Schmid, Vahid Majidzadeh Bafar

An impulse radio ultra wideband (IR-UWB) transmitter (Tx) using finite impulse response synthesis of the raised-cosine pulse is presented. Symmetric pulse combining technique is proposed to reduce the number of power amplifier elements by half. A novel all ...

2012

Towards oscillation-free implementation of the immersed boundary method with spectral-like methods

Marc Parlange, Jiannong Fang, Chad Higgins, Marc Diebold

It is known that, when the immersed boundary method (IBM) is implemented within spectral-like methods, the Gibbs oscillation seriously deteriorates the calculation of derivatives near the body surface. In this paper, a radial basis function (RBF) based smo ...

Elsevier2011

Piecewise polynomial phase approximation approach for the analysis of reconstructed interference felds in digital holographic interferometry

Pramod Rastogi, Sai Siva Gorthi

This paper proposes a new approach for the analysis of reconstructed interference fields in digital holographic interferometry. In the proposed approach the interference phase to be estimated is conceived as a piecewise polynomial signal; consequently, eac ...

Institute of Physics2009

Exact Local Reconstruction Algorithms for Signals with Finite Rate of Innovation

Martin Vetterli, Thierry Blu, Pier Luigi Dragotti

Consider the problem of sampling signals which are not bandlimited, but still have a finite number of degrees of freedom per unit of time, such as, for example, piecewise polynomial or piecewise sinusoidal signals, and call the number of degrees of freedom ...

2006

Solving the Couette inverse problem using a wavelet-vaguelette decomposition

Christophe Ancey

This paper develops a new approach to computing the shear rate from the torque and rotationalvelocity measurements in a Couette rheometer. It is based on wavelet-vaguelette decomposition (WVD) proposed by Donoho (Donoho, D., Appl. Comput. Harmon. Anal. 2, ...

2005