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We present a hybrid continuous and discontinuous Galerkin spectral element approximation that leverages the advantages of each approach. The continuous Galerkin approximation is used on interior element faces where the equation properties…

Numerical Analysis · Mathematics 2020-12-14 David A. Kopriva , Gregor J. Gassner

At Argonne National Laboratory, we are developing hard X-ray (2 to 20 keV) Transition Edge Sensor (TES) arrays for beamline science. The significantly improved energy resolution provided by superconducting detectors compared to…

Instrumentation and Detectors · Physics 2021-06-02 T. Guruswamy , L. Gades , A. Miceli , U. Patel , O. Quaranta

Spectroscopic photoemission microscopy is a well-established method to investigate the electronic structure of surfaces. In modern photoemission microscopes the electron optics allows imaging of the image plane, momentum plane, or…

Current matrix elements and observables for electro- and photo-excitation of baryons from the nucleon are studied in a light-front framework. Relativistic effects are estimated by comparison to a nonrelativistic model, where we use simple…

Nuclear Theory · Physics 2014-11-18 Simon Capstick , B. D. Keister

Prior to recombination photons, electrons, and atomic nuclei rapidly scattered and behaved, almost, like a single tightly-coupled photon-baryon plasma. We investigate here the accuracy of the tight-coupling approximation commonly used to…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Francis-Yan Cyr-Racine , Kris Sigurdson

We conduct a study of the aliased spectral densities of Mat\'ern covariance functions on a regular grid of points, providing clarity on the properties of a popular approximation based on stochastic partial differential equations; while…

Computation · Statistics 2021-03-03 Joseph Guinness

High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation and high flux…

Instrumentation and Methods for Astrophysics · Physics 2016-04-06 J. -R. Delorme , R. Galicher , P. Baudoz , G. Rousset , J. Mazoyer , O. Dupuis

We study how the energy and momentum resolution of angle-resolved photoemission spectroscopy (ARPES) affects the linewidth, Fermi crossing, velocity, and curvature of the measured band structure. Based on the fact that the resolution…

Strongly Correlated Electrons · Physics 2015-06-16 G. Levy , W. Nettke , B. M. Ludbrook , C. N. Veenstra , A. Damascelli

Spectral computed tomography has received considerable interest in recent years since spectral measurements contain much richer information about the object of interest. In spectral computed tomography, we are interested in the energy…

Numerical Analysis · Mathematics 2022-03-04 Katrine O Bangsgaard , Genoveva Burca , Evelina Ametova , Martin S Andersen , Jakob S Jørgensen

Matrix completion constantly receives tremendous attention from many research fields. It is commonly applied for recommender systems such as movie ratings, computer vision such as image reconstruction or completion, multi-task learning such…

Machine Learning · Computer Science 2019-10-08 Abdallah Chehade , Zunya Shi

This paper proposes a novel feature called spectrum congruency for describing edges in images. The spectrum congruency is a generalization of the phase congruency, which depicts how much each Fourier components of the image are congruent in…

Image and Video Processing · Electrical Eng. & Systems 2021-03-11 Fang Yang , Xin Su , Li Chai

The rectangular multiparameter eigenvalue problem (RMEP) involves rectangular coefficient matrices (usually with more rows than columns) and may potentially have no solution in its original form. A minimal perturbation framework is proposed…

Numerical Analysis · Mathematics 2025-08-11 Shanheng Han , Lei-Hong Zhang , Ren-Cang Li

This paper derives exponential tail bounds and polynomial moment inequalities for the spectral norm deviation of a random matrix from its mean value. The argument depends on a matrix extension of Stein's method of exchangeable pairs for…

Probability · Mathematics 2013-05-06 Daniel Paulin , Lester Mackey , Joel A. Tropp

We propose the timescale-resolved spectroscopy (TRS) as a new method to combine the timing and spectral study. TRS is based on the time domain power spectrum and reflects the variable amplitudes of spectral components on different…

Instrumentation and Methods for Astrophysics · Physics 2014-11-18 Y. X. Wu , T. P. Li , T. M. Belloni , T. S. Wang , H. Liu

ARPES is a widely used characterization technique in condensed matter physics, providing direct access to the single-electron spectral function of crystals, including their electronic band structure and Fermi surface. Measuring the band…

In recent years, strong-field physics in condensed-matter was pioneered as a novel approach for controlling material properties through laser-dressing, as well as for ultrafast spectroscopy via nonlinear light-matter interactions (e.g.…

The search for Earth-like exoplanets requires high-contrast and high-angular resolution instruments, which designs can be very complex: they need an adaptive optics system to compensate for the effect of the atmospheric turbulence on image…

Instrumentation and Methods for Astrophysics · Physics 2020-12-16 Lucie Leboulleux , Raphaël Galicher , Eric Gendron , Pierre Baudoz , Gérard Rousset

Using the finite simulation-cell homogeneous electron gas (HEG) as a model, we investigate the convergence of the correlation energy to the complete basis set (CBS) limit in methods utilising plane-wave wavefunction expansions. Simple…

Computational Physics · Physics 2012-09-11 James J. Shepherd , Andreas Grüneis , George H. Booth , Georg Kresse , Ali Alavi

In fiber-based spectroscopy within telescopes, a prevailing limitation has been the necessity to align the fiber diameter with the telescope's seeing conditions, often characterized by the Full Width at Half Maximum of the point spread…

Instrumentation and Methods for Astrophysics · Physics 2024-06-25 Nitish Singh , S. Sriram , Bharat Kumar Yerra , Prasanna G. Deshmukh

A new approach for the parallel forward modeling of transient electromagnetic (TEM) fields is presented. It is based on a family of uniform-in-time rational approximants to the matrix exponential that share a common denominator independent…

Numerical Analysis · Mathematics 2025-06-16 Ralph-Uwe Börner , Stefan Güttel