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We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as…

Solar and Stellar Astrophysics · Physics 2009-11-05 Ashley D. Crouch , Graham Barnes , K. D. Leka

A modular method was suggested before to recover a band limited signal from the sample and hold and linearly interpolated (or, in general, an nth-order-hold) version of the regular samples. In this paper a novel approach for compensating…

Computer Vision and Pattern Recognition · Computer Science 2012-05-15 Mohammad Tofighi , Ali Ayremlou , Farokh Marvasti

This paper is concerned with uniqueness, phase retrieval and shape reconstruction methods for solving inverse electromagnetic source scattering problems with multi-frequency sparse phased or phaseless far field data. With the phased data,…

Analysis of PDEs · Mathematics 2019-06-07 Xia Ji , Xiaodong Liu

We propose a non grid-based interpolation scheme based on the information from the data collected from the vicinity of the query point. As a non-grid-based interpolation, the data points can be distributed randomly in a small region, and…

Numerical Analysis · Mathematics 2016-09-21 Kai Lin , Wei-Liang Qian

We suggest a two-dimensional wavelet devised to deduce the large-scale structure of a physical field (e.g., the Galactic magnetic field) from its integrals along straight paths from irregularly spaced data points to a fixed interior point…

Astrophysics · Physics 2009-11-07 R. Stepanov , P. Frick , A. Shukurov , D. Sokoloff

The Hermite-Birkhoff interpolation problem of a function given on arbitrarily distributed points on the sphere and other manifolds is considered. Each proposed interpolant is expressed as a linear combination of basis functions, the…

Numerical Analysis · Mathematics 2017-05-03 Giampietro Allasia , Roberto Cavoretto , Alessandra De Rossi

Based on realistic simulations, we propose an hybrid method to reconstruct the lensing potential power spectrum, directly on PLANCK-like CMB frequency maps. It implies using a large galactic mask and dealing with a strong inhomogeneous…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 S. Plaszczynski , A. Lavabre , L. Perotto , J. -L. Starck

Multi-fidelity simulation is a widely used strategy to reduce the computational cost of many-query numerical simulation tasks such as uncertainty quantification, design space exploration, and design optimization. The reduced basis approach…

Numerical Analysis · Mathematics 2025-09-17 Murray Cutforth , Tiffany Fan , Tony Zahtila , Alireza Doostan , Eric Darve

We investigate an interpolation/extrapolation method that, given scattered observations of the Fourier transform, approximates its inverse. The interpolation algorithm takes advantage of modelling the available data via a shape-driven…

Numerical Analysis · Mathematics 2021-09-22 Emma Perracchione , Anna Maria Massone , Michele Piana

We investigate the problem of probing the local spatial structure of the magnetic field of the interstellar medium using multi-frequency polarized maps of the synchrotron emission at radio wavelengths. We focus in this paper on the…

Astrophysics of Galaxies · Physics 2015-05-14 Jerome Thiebaut , Simon Prunet , Christophe Pichon , Eric Thiébaut

Lagrangian trajectory or particle dispersion models as well as semi-Lagrangian advection schemes require meteorological data such as wind, temperature and geopotential at the exact spatio-temporal locations of the particles that move…

Atmospheric and Oceanic Physics · Physics 2022-06-09 Rüdiger Brecht , Lucie Bakels , Alex Bihlo , Andreas Stohl

This paper investigates the inverse biharmonic scattering problems of identifying the shape and location of the obstacle with phased and phaseless measurement data. A direct imaging method based on reverse time migration is proposed for…

Analysis of PDEs · Mathematics 2026-05-12 Tielei Zhu , Zhihao Ge

Sparse grids based on Lagrange polynomials have become one of the staple methods for approximating functions that are high-dimensional and expensive to evaluate, in the context e.g. of PDE-based parametric design exploration. They are…

Computational Engineering, Finance, and Science · Computer Science 2026-03-10 Matteo Rosellini , Filippo Fruzza , Alessandro Mariotti , Maria Vittoria Salvetti , Lorenzo Tamellini

Estimating spatially distributed information through the interpolation of scattered observation datasets often overlooks the critical role of domain knowledge in understanding spatial dependencies. Additionally, the features of these data…

Machine Learning · Computer Science 2024-09-09 Cong Zhang , Shuyi Du , Hongqing Song , Yuhe Wang

The OLYMPUS experiment used a 0.3 T toroidal magnetic spectrometer to measure the momenta of outgoing charged particles. In order to accurately determine particle trajectories, knowledge of the magnetic field was needed throughout the…

CONTEXT: As the coronal magnetic field can usually not be measured directly, it has to be extrapolated from photospheric measurements into the corona. AIMS: We test the quality of a non-linear force-free coronal magnetic field extrapolation…

We design a conservative finite difference scheme for ideal magnetohydrodynamic simulations that attains high-order accuracy, shock-capturing, and divergence-free condition of the magnetic field. The scheme interpolates pointwise physical…

Instrumentation and Methods for Astrophysics · Physics 2019-06-05 Takashi Minoshima , Takahiro Miyoshi , Yosuke Matsumoto

The interpolation-regression approximation is a powerful tool in numerical analysis for reconstructing functions defined on square or triangular domains from their evaluations at a regular set of nodes. The importance of this technique lies…

Numerical Analysis · Mathematics 2025-08-12 Francesco Dell'Accio , Francisco Marcellán , Federico Nudo

In the frame of volume integral equation methods, we introduce an alternative representation of the electromagnetic field scattered by a homogeneous object of arbitrary shape at a given frequency, in terms of a set of modes independent of…

In this paper, we propose a new trigonometric interpolation algorithm and establish relevant convergent properties. The method adjusts an existing trigonometric interpolation algorithm such that it can better leverage Fast Fourier Transform…

Numerical Analysis · Mathematics 2025-05-06 Xiaorong Zou