Results for "Virginie Ehrlacher"

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Approximation of Optimal Transport problems with marginal moments constraintsMay 14 2019Optimal Transport (OT) problems arise in a wide range of applications, from physics to economics. Getting numerical approximate solution of these problems is a challenging issue of practical importance. In this work, we investigate the relaxation of the ... More
Statistical methods for critical scenarios in aeronauticsSep 04 2014Feb 09 2015We present numerical results obtained on the CEMRACS project Predictive SMS proposed by Safety Line. The goal of this work was to elaborate a purely statistical method in order to reconstruct the deceleration profile of a plane during landing under normal ... More
An embedded corrector problem to approximate the homogenized coefficients of an elliptic equationDec 19 2014We consider a diffusion equation with highly oscillatory coefficients that admits a homogenized limit. As an alternative to standard corrector problems, we introduce here an embedded corrector problem, written as a diffusion equation in the whole space ... More
A dynamical adaptive tensor method for the Vlasov-Poisson systemJun 21 2016A numerical method is proposed to solve the full-Eulerian time-dependent Vlasov-Poisson system in high dimension. The algorithm relies on the construction of a tensor decomposition of the solution whose rank is adapted at each time step. This decomposition ... More
Cross-diffusion systems with non-zero-flux boundary conditions on a moving domainNov 23 2016We propose and analyze a one-dimensional multi-species cross-diffusion system with non-zero-flux boundary conditions on a moving domain, motivated by the mod- eling of a Physical Vapor Deposition process. Using the boundedness by entropy method, we prove ... More
Greedy algorithms for high-dimensional eigenvalue problemsApr 09 2013In this article, we present two new greedy algorithms for the computation of the lowest eigenvalue (and an associated eigenvector) of a high-dimensional eigenvalue problem, and prove some convergence results for these algorithms and their orthogonalized ... More
Greedy algorithms for high-dimensional non-symmetric linear problemsOct 24 2012In this article, we present a family of numerical approaches to solve high-dimensional linear non-symmetric problems. The principle of these methods is to approximate a function which depends on a large number of variates by a sum of tensor product functions, ... More
Periodic Schrödinger operators with local defects and spectral pollutionNov 16 2011This article deals with the numerical calculation of eigenvalues of perturbed periodic Schr\"odinger operators located in spectral gaps. Such operators are encountered in the modeling of the electronic structure of crystals with local defects, and of ... More
Non-consistent approximations of self-adjoint eigenproblems: Application to the supercell methodMay 02 2012In this article, we introduce a general theoretical framework to analyze non-consistent approximations of the discrete eigenmodes of a self-adjoint operator. We focus in particular on the discrete eigenvalues laying in spectral gaps. We first provide ... More
Strong solutions and weak-strong stability in a system of cross-diffusion equationsDec 27 2018Proving the uniqueness of solutions to multi-species cross-diffusion systems is a difficult task in the general case, and there exist very few results in this direction. In this work, we study a particular system with zero-flux boundary conditions for ... More
An embedded corrector problem for homogenization. Part I: TheoryJul 13 2018This article is the first part of a two-fold study, the objective of which is the theoretical analysis and numerical investigation of new approximate corrector problems in the context of stochastic homogenization. We present here three new alternatives ... More
A progressive reduced basis/empirical interpolation method for nonlinear parabolic problemsOct 02 2017Apr 20 2018We investigate new developments of the combined Reduced-Basis and Empirical Interpolation Methods (RB-EIM) for parametrized nonlinear parabolic problems. In many situations, the cost of the EIM in the offline stage turns out to be prohibitive since a ... More
An embedded corrector problem for homogenization. Part II: Algorithms and discretizationOct 23 2018This contribution is the numerically oriented companion article of the work [E. Canc\`es, V. Ehrlacher, F. Legoll, B. Stamm and S. Xiang, arxiv preprint 1807.05131]. We focus here on the numerical resolution of the embedded corrector problem introduced ... More
Numerical quadrature in the Brillouin zone for periodic Schrodinger operatorsMay 18 2018As a consequence of Bloch's theorem, the numerical computation of the fermionic ground state density matrices and energies of periodic Schrodinger operators involves integrals over the Brillouin zone. These integrals are difficult to compute numerically ... More
Low-rank approximation of linear parabolic equations by space-time tensor Galerkin methodsDec 19 2017Oct 10 2018We devise a space-time tensor method for the low-rank approximation of linear parabolic evolution equations. The proposed method is a stable Galerkin method, uniformly in the discretization parameters, based on a Minimal Residual formulation of the evolution ... More
Modeles Multiparticulaires Des Materiaux Multicouches M4_5n et M4_(2n+1)M Pour L'Analyse Des Effets De Bord Multiparticle Models of Multilayered Materials M4_5n and M4_(2n+1)M for Edge Effect AnalysisSep 29 2008The Multiparticle Models of Multilayered Materials (models M4) are developed to analyze easily the 3D stress fields which produce delamination or transverse crackings in laminates. The M4 models are built from 3D approximate stress fields in z per layer ... More
Non-proper Actions of the Fundamental Group of a Punctured TorusNov 04 2003Given an affine isometry of $\R^3$ with hyperbolic linear part, its Margulis invariant measures signed Lorentzian displacement along an invariant spacelike line. In order for a group generated by hyperbolic isometries to act properly on $\R^3$, the sign ... More
A Possible Dynamical History for the Fomalhaut SystemOct 13 2015Fomalhaut b was long thought to shape the eccentric debris belt in the Fomalhaut system, but its orbit was found to be too eccentric for it to be the dominant belt-shaping perturber. This indicates that Fomalhaut b is Earth-sized at most and that the ... More
Analysis of Boundary Conditions for Crystal Defect Atomistic SimulationsJun 22 2013May 23 2016Numerical simulations of crystal defects are necessarily restricted to finite computational domains, supplying artificial boundary conditions that emulate the effect of embedding the defect in an effectively infinite crystalline environment. This work ... More
Deconvolution of HST images of the Cloverleaf gravitational lens : detection of the lensing galaxy and a partial Einstein ringDec 04 2006Archival HST/NICMOS-2 images of the Cloverleaf gravitational lens (H1413+117), a quadruply imaged quasar, have been analysed with a new method derived from the MCS deconvolution algorithm (Magain et al., 1998). This method is based on an iterative process ... More
Non uniform stability for the Timoshenko beam with tip loadJul 02 2015In this paper we consider a hybrid elastic model consisting of a Timoshenko beam and a tip load at the free end of the beam. Under the equal speed wave propagation condition, we show polynomial decay for the model which includes the rotary inertia of ... More
Gravitational lensing evidence against extended dark matter halosMar 27 2013It is generally thought that galaxies are embedded in dark matter halos extending well beyond their luminous matter. The existence of these galactic halos is mainly derived from the larger than expected velocities of stars and gas in the outskirts of ... More
Structuring polymer gels via catalytic reactionsAug 16 2016Nov 09 2017We use computer simulations to investigate how a catalytic reaction in a polymer sol can induce the formation of a polymer gel. To this aim we consider a solution of homopolymers in which freely-diffusing catalysts convert the originally repulsive A monomers ... More
Structuring polymer gels via catalytic reactionsAug 16 2016We use computer simulations to investigate how a catalytic reaction can induce the formation of a polymer gel. To this aim we consider a polymer solution in which freely-diffusing catalysts convert the originally repulsive monomers into attractive ones. ... More
Mean position of a particle submitted to a potential barrierSep 23 2008A one-dimensional Klein-Gordon problem, which is a physical model for a quantum particle submitted to a potential barrier, is studied numerically : using a variational formulation and a Newmark numerical method, we compute the mean position and standard ... More
Spectral minimal partitions for a family of toriMar 16 2015Apr 22 2016We study partitions of the rectangular two-dimensional flat torus of length 1 and width b into k domains, with b a parameter in (0, 1] and k an integer. We look for partitions which minimize the energy, definedas the largest first eigenvalue of the Dirichlet ... More
Affine Schottky Groups and Crooked TilingsMay 08 2010In his 1990 doctoral thesis, Todd Drumm showed that proper affine deformations of free Fuchsian groups could be constructed as Schottky groups using a new family of hypersurfaces called "crooked planes." The existence of proper affine deformations of ... More
Nodal and spectral minimal partitions -- The state of the art in 2015 --Jun 24 2015In this article, we propose a state of the art concerning the nodal and spectral minimal partitions. First we focus on the nodal partitions and give some examples of Courant sharp cases. Then we are interested in minimal spectral partitions. Using the ... More
Optimal partitions for the sum and the maximum of eigenvaluesFeb 06 2017In this paper we compare the candidates to be spectral minimal partitions for two criteria: the maximum and the average of the first eigenvalue on each subdomains of the partition. We analyze in detail the square, the disk and the equilateral triangle. ... More
McShane-type Identities for Affine DeformationsJul 07 2015Oct 07 2016We derive an identity for Margulis invariants of affine deformations of a complete orientable one-ended hyperbolic sur- face following the identities of McShane, Mirzakhani and Tan- Wong-Zhang. As a corollary, a deformation of the surface which infinitesimally ... More
Magnetic Neumann Laplacian on a sharp coneSep 10 2013This paper is devoted to the spectral analysis of the Laplacian with constant magnetic field on a cone of aperture $\alpha$ and Neumann boundary condition. We analyze the influence of the orientation of the magnetic field. In particular, for any orientation ... More
Ground state energy of the magnetic Laplacian on corner domainsMar 27 2014Jan 06 2016The asymptotic behavior of the first eigenvalues of magnetic Laplacian operators with large magnetic fields and Neumann realization in smooth three-dimensional domains is characterized by model problems inside the domain or on its boundary. In two-dimensional ... More
Let Me Not Lie: Learning MultiNomial LogitDec 23 2018Discrete choice models generally assume that model specification is known a priori. In practice, determining the utility specification for a particular application remains a difficult task and model misspecification may lead to biased parameter estimates. ... More
Semiclassical tunneling and magnetic flux effects on the circleMay 18 2015Aug 26 2015This paper is devoted to semiclassical tunneling estimates induced on the circle by a double well electric potential in the case when a magnetic field is added. When the two electric wells are connected by two geodesics for the Agmon distance, we highlight ... More
Magnetic WKB ConstructionsMay 28 2014Jan 21 2016This paper is devoted to the semiclassical magnetic Laplacian. Until now WKB expansions for the eigenfunctions were only established in presence of a non-zero electric potential. Here we tackle the pure magnetic case. Thanks to Feynman-Hellmann type formulas ... More
Kidnapping Model: An Extension of Selten's GameSep 22 2017Selten's game is a kidnapping model where the probability of capturing the kidnapper is independent of whether the hostage has been released or executed. Most often, in view of the elevated sensitivities involved, authorities put greater effort and resources ... More
Magnetic chirality as probed by neutron scatteringJan 08 2013We review the concept of chirality, at first briefly in a general context then in the specific framework of the spin networks. We next discuss to what extent neutron scattering appears as an unconvertible tool to probe magnetic chirality in the static ... More
Interactions between moderately close inclusions for the 2D Dirichlet-LaplacianFeb 25 2015Jun 29 2015This paper concerns the asymptotic expansion of the solution of the Dirichlet-Laplace problem in a domain with small inclusions. This problem is well understood for the Neumann condition in dimension greater than two or Dirichlet condition in dimension ... More
Eigen-Epistasis for detecting Gene-Gene interactionsFeb 17 2016Nov 18 2016A large amount of research has been devoted to the detection and investigation of epistatic interactions in genome-wide association studies (GWASs). Most of the literature focuses on low-order interactions between single-nucleotide polymorphisms (SNPs) ... More
Holomorphic extension of the de Gennes functionDec 13 2016This note is devoted to prove that the de Gennes function has a holomorphic extension on a strip containing the real axis.
Gaussian and Sparse Processes Are Limits of Generalized Poisson ProcessesFeb 16 2017The theory of sparse stochastic processes offers a broad class of statistical models to study signals. In this framework, signals are represented as realizations of random processes that are solution of linear stochastic differential equations driven ... More
Closed Timelike Curves in Flat Lorentz SpacetimesJan 21 2002Jul 10 2002We consider the region of closed timelike curves (CTC's) in three-dimensional flat Lorentz spacetimes. The interest in this global geometrical feature goes beyond the purely mathematical. Such spacetimes may be considered lower-dimensional toy models ... More
Permeability through a perforated domain for the incompressible 2D Euler equationsJun 17 2013We investigate the influence of a perforated domain on the 2D Euler equations. Small inclusions of size $\varepsilon$ are uniformly distributed on the unit segment or a rectangle, and the fluid fills the exterior. These inclusions are at least separated ... More
The diffusion dynamics of choice: From durable goods markets to fashion first namesApr 01 2014Goods, styles, ideologies are adopted by society through various mechanisms. In particular, adoption driven by innovation is extensively studied by marketing economics. Mathematical models are currently used to forecast the sales of innovative goods. ... More
An adaptive embedded architecture for real-time Particle Image Velocimetry algorithmsJul 23 2008Particle Image Velocimetry (PIV) is a method of im-aging and analysing fields of flows. The PIV tech-niques compute and display all the motion vectors of the field in a resulting image. Speeds more than thou-sand vectors per second can be required, each ... More
Ground Energy of the Magnetic Laplacian in Polyhedral BodiesSep 20 2013Dec 04 2013The asymptotic behavior of the first eigenvalues of magnetic Laplacian operators with large magnetic fields and Neumann realization in polyhedral domains is characterized by a hierarchy of model problems. We investigate properties of the model problems ... More
Structure and dynamics of a polymer-nanoparticle composite: Effect of nanoparticle size and volume fractionApr 19 2018Sep 16 2018We use molecular dynamics simulations to study a semidilute, unentangled polymer solution containing well dispersed, weakly attractive nanoparticles (NP) of size ($\sigma_N$) smaller than the polymer radius of gyration $R_g$. We find that if $\sigma_N$ ... More
Characterizing the mesh size of polymer solutions via the pore size distributionAug 05 2019In order to characterize the geometrical mesh size $\xi$, we simulate a solution of coarse-grained polymers with densities ranging from the dilute to the concentrated regime and for different chain lengths. Conventional ways to estimate $\xi$ rely either ... More
Eigen-Epistasis for detecting Gene-Gene interactionsFeb 17 2016Jun 20 2016A large amount of research has been devoted to the detection and investigation of epistatic interactions in genome-wide association studies (GWASs). Most of the literature focuses on low-order interactions between single-nucleotide polymorphisms (SNPs) ... More
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VIII. Deconvolution of high resolution near-IR images and simple mass models for 7 gravitationally lensed quasarsJul 19 2010Jul 22 2010We apply the iterative MCS deconvolution method (ISMCS) to near-IR HST archives data of seven gravitationally lensed quasars currently monitored by the COSMOGRAIL collaboration: HE 0047-1756, RX J1131-1231, SDSS J1138+0314, SDSS J1155+6346, SDSS J1226-0006, ... More
Bisectors determining unique pairs of points in the bidiskAug 26 2016Bisectors are equidistant hypersurfaces between two points and are basic objects in a metric geometry. They play an important part in understanding the action of subgroups of isometries on a metric space. In many metric geometries (spherical, Euclidean, ... More
Towards Grid Monitoring and deployment in Jade, using ProActiveOct 29 2007This document describes our current effort to gridify Jade, a java-based environment for the autonomic management of clustered J2EE application servers, developed in the INRIA SARDES research team. Towards this objective, we use the java ProActive grid ... More
Fundamental domains in the Einstein UniverseJul 24 2013Jun 25 2014We will discuss fundamental domains for actions of discrete groups on the 3-dimensional Einstein Universe. These will be bounded by crooked surfaces, which are conformal compactifications of surfaces that arise in the construction of Margulis spacetimes. ... More
Addition to Structure and dynamics of a polymer-nanoparticle composite: Effect of nanoparticle size and volume fractionJul 29 2019In our previous publication (Ref. 1) we have shown that the data for the normalized diffusion coefficient of the polymers, $D_p/D_{p0}$, falls on a master curve when plotted as a function of $h/\lambda_d$, where $h$ is the mean interparticle distance ... More
Micelle formation, gelation and phase separation of amphiphilic multiblock copolymersFeb 16 2011The phase behaviour of amphiphilic multiblock copolymers with a large number of blocks in semidilute solutions is studied by lattice Monte Carlo simulations. The influence on the resulting structures of the concentration, the solvent quality and the ratio ... More
Hydration of Clays at the Molecular Scale: The Promising Perspective of Classical Density Functional TheoryFeb 11 2014Apr 25 2014We report here how the hydration of complex surfaces can be efficiently studied thanks to recent advances in classical molecular density functional theory. This is illustrated on the example of the pyrophylite clay. After presenting the most recent advances, ... More
Targeting realistic geometry in Tokamak code GyselaNov 20 2017In magnetically confined plasmas used in Tokamak, turbulence is responsible for specific transport that limits the performance of this kind of reactors. Gyrokinetic simulations are able to capture ion and electron turbulence that give rise to heat losses, ... More
Finite-sided deformation spaces of complete affine 3-manifoldsJul 14 2011Nov 17 2012A Margulis spacetime is a complete affine 3-manifold M with nonsolvable fundamental group. Associated to every Margulis spacetime is a noncompact complete hyperbolic surface S. We show that every Margulis spacetime is orientable, even though S may be ... More
Magnetic Laplacian in sharp three dimensional conesMay 12 2015Mar 23 2016The core result of this paper is an upper bound for the ground state energyof the magnetic Laplacian with constant magnetic field on cones that are contained in ahalf-space. This bound involves a weighted norm of the magnetic field related to momentson ... More
A conservative coupling algorithm between a compressible flow and a rigid body using an Embedded Boundary methodDec 25 2010Jun 17 2015This paper deals with a new solid-fluid coupling algorithm between a rigid body and an unsteady compressible fluid flow, using an Embedded Boundary method. The coupling with a rigid body is a first step towards the coupling with a Discrete Element method. ... More
Adaptive FPGA NoC-based Architecture for Multispectral Image CorrelationJan 26 2009An adaptive FPGA architecture based on the NoC (Network-on-Chip) approach is used for the multispectral image correlation. This architecture must contain several distance algorithms depending on the characteristics of spectral images and the precision ... More
Affine deformations of a three-holed sphereJul 03 2009Associated to every complete affine 3-manifold M with nonsolvable fundamental group is a noncompact hyperbolic surface S. We classify such complete affine structures when Sigma is homeomorphic to a three-holed sphere. In particular, for every such complete ... More
Improved nonlinear plasmonic slot waveguide: a full studyMar 16 2016We present a full study of an improved nonlinear plasmonic slot waveguides (NPSWs) in which buffer linear dielectric layers are added between the Kerr type nonlinear dielectric core and the two semi-infinite metal regions. For TM polarized waves, the ... More
Numerical periodic normalization for codim 2 bifurcations of limit cycles with center manifold of dimension higher than 3Oct 23 2012Explicit computational formulas for coefficients of the periodic normal forms of the three most complex codim 2 bifurcations of limit cycles with dimension of the center manifold equal to 4 or to 5 in generic autonomous ODEs are derived. The resulting ... More
Design of mid-IR and THz quantum cascade laser cavities with complete TM photonic bandgapJan 11 2007We present the design of mid-infrared and THz quantum cascade laser cavities formed from planar photonic crystals with a complete in-plane photonic bandgap. The design is based on a honeycomb lattice, and achieves a full in-plane photonic gap for transverse-magnetic ... More
Equidistant hypersurfaces of the bidiskJun 06 2012The following are notes on the geometry of the bidisk. In particular, we examine the properties of equidistant surfaces in the bidisk.
Inner mean-motion resonances with eccentric planets: A possible origin for exozodiacal dust cloudsNov 07 2016High levels of dust have been detected in the immediate vicinity of many stars, both young and old. A promising scenario to explain the presence of this short-lived dust is that these analogues to the Zodiacal cloud (or exozodis) are refilled in situ ... More
Lower bounds on information complexity via zero-communication protocols and applicationsApr 06 2012Jan 18 2013We show that almost all known lower bound methods for communication complexity are also lower bounds for the information complexity. In particular, we define a relaxed version of the partition bound of Jain and Klauck and prove that it lower bounds the ... More
Diverse M-Best Solutions by Dynamic ProgrammingMar 15 2018Many computer vision pipelines involve dynamic programming primitives such as finding a shortest path or the minimum energy solution in a tree-shaped probabilistic graphical model. In such cases, extracting not merely the best, but the set of M-best solutions ... More
Computation of the Hydrodynamic Radius of Charged Nanoparticles from Non-equilibrium Molecular DynamicsMay 09 2018We have used non-equilibrium molecular dynamics to simulate the flow of water molecules around a charged nanoparticle described at the atomic scale. These non-equilibrium simulations allowed us to compute the friction coefficient of the nanoparticle and ... More
Proper affine deformation spaces of two-generator Fuchsian groupsJan 19 2015A Margulis spacetime is a complete flat Lorentzian 3-manifold M with free fundamental group. Associated to M is a noncompact complete hyperbolic surface S homotopy-equivalent to M. The purpose of this paper is to classify Margulis spacetimes when S is ... More
The Influence of the Tunnel Effect on L-infinity-time decayApr 15 2011We consider the Klein-Gordon equation on a star-shaped network composed of n half-axes connected at their origins. We add a potential which is constant but different on each branch. Exploiting a spectral theoretic solution formula from a previous paper, ... More
A Chandra X-ray and Infrared Study of the Stellar Population in the High-Mass Star Forming Region IRAS 16562-3959Jun 16 2018We present the results from Chandra X-ray observations, and near- and mid-infrared analysis, using VISTA/VVV and Spitzer/GLIMPSE catalogs, of the high-mass star-forming region IRAS 16562-3959, which contains a candidate for a high mass protostar. We detected ... More
Multiple tunnel effect for dispersive waves on a star-shaped network: an explicit formula for the spectral representationDec 14 2010We consider the Klein-Gordon equation on a star-shaped network composed of n half-axes connected at their origins. We add a potential which is constant but different on each branch. The corresponding spatial operator is self-adjoint and we state explicit ... More
On the eigenvalues of Aharonov-Bohm operators with varying polesOct 04 2013We consider a magnetic operator of Aharonov-Bohm type with Dirichlet boundary conditions in a planar domain. We analyse the behavior of its eigenvalues as the singular pole moves in the domain. For any value of the circulation we prove that the k-th magnetic ... More
Bayesian Lower Bounds for Dense or Sparse (Outlier) Noise in the RMT FrameworkMay 14 2016Robust estimation is an important and timely research subject. In this paper, we investigate performance lower bounds on the mean-square-error (MSE) of any estimator for the Bayesian linear model, corrupted by a noise distributed according to an i.i.d. ... More
Bayesian Lower Bounds for Dense or Sparse (Outlier) Noise in the RMT FrameworkMay 14 2016Jul 11 2017Robust estimation is an important and timely research subject. In this paper, we investigate performance lower bounds on the mean-square-error (MSE) of any estimator for the Bayesian linear model, corrupted by a noise distributed according to an i.i.d. ... More
NLP and CALL: integration is workingFeb 20 2013In the first part of this article, we explore the background of computer-assisted learning from its beginnings in the early XIXth century and the first teaching machines, founded on theories of learning, at the start of the XXth century. With the arrival ... More
Crooked HalfspacesNov 18 2012May 17 2013We develop the Lorentzian geometry of a crooked halfspace in 2+1-dimensional Minkowski space. We calculate the affine, conformal and isometric automorphism groups of a crooked halfspace, and discuss its stratification into orbit types, giving an explicit ... More
Nodal domains, spectral minimal partitions, and their relation to Aharonov-Bohm operatorsNov 02 2017This survey is a short version of a chapter written by the first two authors in the book [A. Henrot, editor. Shape optimization and spectral theory. Berlin: De Gruyter, 2017] (where more details and references are given) but we have decided here to put ... More
Einstein tori and crooked surfacesFeb 27 2017In hyperbolic space, the angle of intersection and distance classify pairs of totally geodesic hyperplanes. A similar algebraic invariant classifies pairs of hyperplanes in the Einstein universe. In dimension 3, symplectic splittings of a 4-dimensional ... More
Sparse dictionary learning for 2D Kendall shapesMar 27 2019We propose a novel sparse dictionary learning method for planar shapes in the sense of Kendall, i.e., configurations of landmarks in the plane considered up to similitudes. Our shape dictionary method provides a good trade-off between algorithmic simplicity ... More
Energy flow above the threshold of tunnel effectNov 04 2011We consider the Klein-Gordon equation on two half-axes connected at their origins. We add a potential that is constant but different on each branch. In a previous paper, we studied the L-infinity-time decay via H\"ormander's version of the stationary ... More
Magnetic frustration in an iron based Cairo pentagonal latticeJan 05 2010The Fe3+ lattice in the Bi2Fe4O9 compound is found to materialize the first analogue of a magnetic pentagonal lattice. Due to its odd number of bonds per elemental brick, this lattice, subject to first neighbor antiferromagnetic interactions, is prone ... More
Support and Approximation Properties of Hermite SplinesFeb 07 2019In this paper, we formally investigate two mathematical aspects of Hermite splines which translate to features that are relevant to their practical applications. We first demonstrate that Hermite splines are maximally localized in the sense that their ... More
X-ray and Radio Observations of the Massive Star Forming Region IRAS 20126+4104Feb 18 2015We present results of Chandra ACIS-I and Karl G. Jansky Very Large Array (VLA) 6 cm continuum observations of the IRAS 20126+4104 massive star forming region. We detect 150 X-ray sources within the 17 arcmin x 17 arcmin ACIS-I field, and a total of 13 ... More
Quantitative imaging of anisotropic material properties with vectorial ptychographyDec 01 2017Jan 11 2018Following the recent establishment of the formalism of vectorial ptychography [Ferrand et al., Opt. Lett. 40, 5144 (2015)], first measurements are reported in the optical range, demonstrating the capability of the proposed method to map the four parameters ... More
Support and Approximation Properties of Hermite SplinesFeb 07 2019Feb 08 2019In this paper, we formally investigate two mathematical aspects of Hermite splines which translate to features that are relevant to their practical applications. We first demonstrate that Hermite splines are maximally localized in the sense that their ... More
Reaching the ideal glass transition by aging polymer filmsNov 11 2016Searching for the ideal glass transition, we exploit the ability of glassy polymer films to explore low energy states in remarkably short time scales. We use 30 nm thick polystyrene (PS) films, which in the supercooled state basically display the bulk ... More
The Klein-Gordon equation with multiple tunnel effect on a star-shaped network: Expansions in generalized eigenfunctionsJun 17 2009We consider the Klein-Gordon equation on a star-shaped network composed of n half-axes connected at their origins. We add a potential which is constant but different on each branch. The corresponding spatial operator is self-adjoint and we state explicit ... More
Cross-code gyrokinetic verification and benchmark on the linear collisionless dynamics of the geodesic acoustic modeMay 18 2017The linear properties of the geodesic acoustic modes (GAM) in tokamaks are investigated by means of the comparison of analytical theory and gyrokinetic numerical simulations. The dependence on the value of the safety factor, finite-orbit-width of the ... More
Robust Calibration of Radio Interferometers in Non-Gaussian EnvironmentDec 06 2016The development of new phased array systems in radio astronomy, as the low frequency array (LOFAR) and the square kilometre array (SKA), formed of a large number of small and flexible elementary antennas, has led to significant challenges. Among them, ... More
Effect of structural distortions on the magnetism of doped spin-Peierls CuGeO3Sep 04 2006Aug 14 2008The chemical selectivity and great sensitivity of the Extended X-ray Absorption Spectroscopy technique allowed the determination, in the paramagnetic phase, of the structural distortions induced by doping in the spin-Peierls CuGeO$_3$ compound. The distorted ... More
Structure and dynamics of l-Ge: Neutron scattering experiments and ab initio molecular dynamics simulationsMar 14 2007We report the first measurements of the dynamics of liquid germanium (l-Ge) by quasi-elastic neutron scattering on time-of-flight and triple-axis spectrometers. These results are compared with simulation data of the structure and dynamics of l-Ge which ... More
Spin liquid correlations in Nd-langasite anisotropic Kagomé antiferromagnetFeb 20 2006May 23 2006Dynamical magnetic correlations in the geometrically frustrated Nd$\_3$Ga$\_5$SiO$\_{14}$ compound were probed by inelastic neutron scattering on a single crystal. A scattering signal with a ring shape distribution in reciprocal space and unprecedented ... More
Magnetic frustration in the spinel compounds Ge Co_2 O_4 and Ge Ni_2 O_4Aug 02 2006In both spinel compounds GeCo$_2$O$_4$ and GeNi$_2$O$_4$ which order antiferromagnetically (at $T_N = 23.5 K$ and $T_{N_1} = 12.13 K$, $T_{N_2} = 11.46 K$) with different Curie Weiss temperatures ($T_{CW}$=80.5 K and -15 K), the usual magnetic frustration ... More
Joint ML calibration and DOA estimation with separated arraysFeb 22 2016Jan 22 2017This paper investigates parametric direction-of-arrival (DOA) estimation in a particular context: i) each sensor is characterized by an unknown complex gain and ii) the array consists of a collection of subarrays which are substantially separated from ... More
Relaxed concentrated MLE for robust calibration of radio interferometersMar 03 2016Jan 22 2017In this paper, we investigate the calibration of radio interferometers in which Jones matrices are considered to model the interaction between the incident electromagnetic field and the antennas of each station. Specifically, perturbation effects are ... More
Ab initio study of bilateral doping within the MoS2-NbS2 systemJun 09 2008We present a systematic study on the stability and the structural and electronic properties of mixed molybdenum-niobium disulphides. Using density functional theory we investigate bilateral doping with up to 25 % of MoS2 (NbS2) by Nb (Mo) atoms, focusing ... More
Bayesian Calibration using Different Prior Distributions: an Iterative Maximum A Posteriori Approach for Radio InterferometersJul 30 2018In this paper, we aim to design robust estimation techniques based on the compound-Gaussian (CG) process and adapted for calibration of radio interferometers. The motivation beyond this is due to the presence of outliers leading to an unrealistic traditional ... More