Publications associées à Spherical basis

A Characterisation Of The Continuum Gaussian Free Field In Arbitrary Dimensions

We prove that under certain mild moment and continuity assumptions, the d-dimensional continuum Gaussian free field is the only stochastic process satisfying the usual domain Markov property and a scaling assumption. Our proof is based on a decomposition o ...

ECOLE POLYTECHNIQUE2022

A smooth basis for atomistic machine learning

Michele Ceriotti, Kevin Kazuki Huguenin-Dumittan, Filippo Bigi

Machine learning frameworks based on correlations of interatomic positions begin with a discretized description of the density of other atoms in the neighborhood of each atom in the system. Symmetry considerations support the use of spherical harmonics to ...

AIP Publishing2022

On the Maximum Power Density of Implanted Antennas within Simplified Body Phantoms

Anja Skrivervik, Mingxiang Gao, Zvonimir Sipus

With the application requirements of wireless technology in implantable bioelectronics, knowledge of the fundamental limits for implanted antennas becomes critical. In this work, we investigated the variation of maximum power density within simplified body ...

IEEE2022

Slice Estimation in Diffusion MRI of Neonatal and Fetal Brains in Image and Spherical Harmonics Domains Using Autoencoders

Meritxell Bach Cuadra, Erick Jorge Canales Rodriguez, Gabriel Girard, Thomas Yu, Hamza Kebiri

Diffusion MRI (dMRI) of the developing brain can provide valuable insights into the white matter development. However, slice thickness in fetal dMRI is typically high (i.e., 3-5 mm) to freeze the in-plane motion, which reduces the sensitivity of the dMRI s ...

SPRINGER INTERNATIONAL PUBLISHING AG2022

Physics-enhanced machine learning with symmetry-adapted and long-range representations

Andrea Grisafi

Theoretical and computational approaches to the study of materials and molecules have, over the last few decades, progressed at an exponential rate. Yet, the possibility of producing numerical predictions that are on par with experimental measurements is t ...

EPFL2021

Infinitesimal asphericity changes the universality of the jamming transition

Matthieu Wyart, Carolina Brito Carvalho dos Santos

The jamming transition of non-spherical particles is fundamentally different from the spherical case. Non-spherical particles are hypostatic at their jamming points, while isostaticity is ensured in the case of the jamming of spherical particles. This stru ...

IOP PUBLISHING LTD2020

A Weak Form Implementation of Nonlinear Axisymmetric Shell Equations With Examples

Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla

We present a weak form implementation of the nonlinear axisymmetric shell equations. This implementation is suitable to study the nonlinear deformations of axisymmetric shells, with the capability of considering a general mid-surface shape, non-homogeneous ...

2019

Rapid measurement and correction of spatiotemporal B-0 field changes using FID navigators and a multi-channel reference image

Tobias Kober

Purpose To measure spatiotemporal B-0 field changes in real time using FID navigators (FIDnavs) and to demonstrate the efficacy of retrospectively correcting high-resolution T2*-weighted images using a novel FIDnav framework. Methods A forward model of the ...

Wiley2020

A reduced order accelerator for time-dependent segregated neutronic solvers

Andreas Pautz, Carlo Fiorina, Alessandro Scolaro, Stefan Radman

The deterministic solution of the neutron transport problem entails the coupled solution of several partial differential equations, one for each energy group, direction and/or spherical harmonic. Several techniques have been devised for accelerating the so ...

PERGAMON-ELSEVIER SCIENCE LTD2018

Improved calibration of vertical scanning optical profilometers for spherical profiles measurements

Toralf Scharf, Wilfried Noell, Jeremy Béguelin

A new method for calibrating optical scanning profilometers is presented. Especially adapted to spherical and aspherical profile measurements, it shows an increase of accuracy bigger than one order of magnitude for radius of curvature measurements. Calibra ...

2018

Sampling and Exact Reconstruction of Pulses with Variable Width

Martin Vetterli, Adam James Scholefield, Loïc Arnaud Baboulaz, Gilles Baechler

Recent sampling results enable the reconstruction of signals composed of streams of fixed-shaped pulses. These results have found applications in topics as varied as channel estimation, biomedical imaging and radio astronomy. However, in many real signals, ...

Institute of Electrical and Electronics Engineers2017

An advanced methodology for the mix design optimization of hot mix asphalt

André-Gilles Dumont, Sara Bressi, Manfred Partl

The bitumen quantity to add to asphalt mixtures depends on the surfaces of aggregates and filler to be coated. The formulas currently available in the literature have limitations such as considering all the fillers with the same specific surface or the agg ...

Elsevier Sci Ltd2016

Single-Shot Imaging with Higher-Dimensional Encoding Using Magnetic Field Monitoring and Concomitant Field Correction

Daniel Gallichan

PurposePatLoc (Parallel Imaging Technique using Localized Gradients) accelerates imaging and introduces a resolution variation across the field-of-view. Higher-dimensional encoding employs more spatial encoding magnetic fields (SEMs) than the corresponding ...

Wiley-Blackwell2015

Inverse Rendering of Lambertian Surfaces Using Subspace Methods

Quy Ha Nguyen, Minh Do

We propose a vector space approach for inverse rendering of a Lambertian convex object with distant light sources. In this problem, the texture of the object and arbitrary lightings are both to be recovered from multiple images of the object and its 3D mod ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Force and Torque Analytical Models of a Reaction Sphere Actuator Based on Spherical Harmonic Rotation and Decomposition

Yves Perriard, Leopoldo Rossini

This paper presents an analytical model for the force and torque developed by a reaction sphere actuator for satellite attitude control. The reaction sphere is an innovative momentum exchange device consisting of a magnetic bearings spherical rotor that ca ...

Ieee-Inst Electrical Electronics Engineers Inc2013

Light confinement effect of non-spherical nanoscale solid immersion lenses

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim, Gaël David Osowiecki, David Nguyen

We report on the light confinement effect observed in non-ideally shaped (i.e., non-spherical) nanoscale solid immersion lenses (SILs). To investigate this effect, nanostructures of various shapes are fabricated by electron-beam lithography. When completel ...

Spie-Int Soc Optical Engineering2013

3DEX: a code for fast spherical Fourier-Bessel decomposition of 3D surveys

Anaïs Marie Rassat, Jean-Luc Starck

Context. High-precision cosmology requires the analysis of large-scale surveys in 3D spherical coordinates, i.e. spherical Fourier-Bessel decomposition. Current methods are insufficient for future data-sets from wide-field cosmology surveys. ...

2012

Spherical 3D isotropic wavelets

Anaïs Marie Rassat, Jean-Luc Starck

Context. Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D spherical Fourier-Bessel (SFB) analysis in spherical coordinates is natural. Wavelets are particularly well-suited to the analysis and d ...

2012

Intrinsic advantages of the w component and spherical imaging for wide-field radio interferometry

Yves Wiaux, Jason Douglas McEwen

Incorporating wide-field considerations in interferometric imaging is of increasing importance for next-generation radio telescopes. Compressed sensing techniques for interferometric imaging have been extended to wide fields recently, recovering images in ...

2011

Harmonic analysis of spherical sampling in diffusion MRI

Jean-Philippe Thiran, Dimitri Nestor Alice Van De Ville, Yves Wiaux, Alessandro Daducci, Jason Douglas McEwen

In the last decade diffusion MRI has become a powerful tool to non-invasively study white-matter integrity in the brain. Recently many research groups have focused their attention on multi-shell spherical acquisitions with the aim of effectively mapping th ...

2011