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We present a model reduction approach for the real-time solution of time-dependent nonlinear partial differential equations (PDEs) with parametric dependencies. The approach integrates several ingredients to develop efficient and accurate…

Numerical Analysis · Mathematics 2024-10-04 Ngoc Cuong Nguyen

We study the light propagation in one-dimensional photonic crystal via nonlinear Four Wave Mixing (FWM) process. The linear and nonlinear refractive indexes are approximated with the first Fourier harmonic term. A system of the nonlinear…

Optics · Physics 2007-05-23 Maryam Boozarjmehr , Ali Rostami

This paper proposes a frequency/time hybrid integral-equation method for the time dependent wave equation in two and three-dimensional spatial domains. Relying on Fourier Transformation in time, the method utilizes a fixed…

Numerical Analysis · Mathematics 2020-04-30 Thomas G. Anderson , Oscar P. Bruno , Mark Lyon

This paper studies the effects on Zernike coefficients of aperture scaling, translation and rotation, when a given aberrated wavefront is described on the Zernike polynomial basis. It proposes a new analytical method for computing the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 Eric Tatulli

The Fourier transform of the indicator function of arbitrary polygons and polyhedra is computed for complex wavevectors. Using the divergence theorem and Stokes' theorem, closed expressions are obtained. Apparent singularities, all…

Mathematical Physics · Physics 2021-06-01 Joachim Wuttke

We present direct logarithmically optimal in theory and fast in practice algorithms to implement the tensor product high order finite element method on multi-dimensional rectangular parallelepipeds for solving PDEs of the Poisson kind. They…

Numerical Analysis · Mathematics 2026-01-05 Alexander Zlotnik , Ilya Zlotnik

We exhibit a method for simultaneously treating recoil and threshold corrections in single-photon inclusive cross sections, working within the formalism of collinear factorization. This approach conserves both the energy and transverse…

High Energy Physics - Phenomenology · Physics 2008-11-26 Eric Laenen , George Sterman , Werner Vogelsang

A statistical model for the polarization of pulsar radio emission is enhanced to account for the heavy modulation of the emission, the possible covariance of the Stokes parameters, and the observed asymmetries in the distributions of total…

High Energy Astrophysical Phenomena · Physics 2022-10-12 M. M. McKinnon

The long-standing paradox of the linear polarization signal of the Na i D1 line was recently resolved by accounting for the atom's hyperfine structure and the detailed spectral structure of the incident radiation field. That modeling relied…

Solar and Stellar Astrophysics · Physics 2023-09-25 Gioele Janett , Ernest Alsina Ballester , Luca Belluzzi , Tanausú del Pino Alemán , Javier Trujillo Bueno

Context. The correct modeling of the scattering polarization signals observed in several strong resonance lines requires taking partial frequency redistribution (PRD) phenomena into account. Aims. This work aims at assessing the impact and…

Polarization asymmetries in photoproduction of high transverse momentum mesons are a flavor sensitive way to measure the polarized quark distributions. We calculate the expected asymmetries in several models, and find that the asymmetries…

High Energy Physics - Phenomenology · Physics 2014-11-17 Andrei Afanasev , Carl E. Carlson , Christian Wahlquist

A reduced-order model algorithm, based on approximations of Lax pairs, is proposed to solve nonlinear evolution partial differential equations. Contrary to other reduced-order methods, like Proper Orthogonal Decomposition, the space where…

Numerical Analysis · Mathematics 2012-11-20 Jean-Frédéric Gerbeau , Damiano Lombardi

The high-frequency Helmholtz equation on the entire space is truncated into a bounded domain using the perfectly matched layer (PML) technique and subsequently, discretized by the higher-order finite element method (FEM) and the continuous…

Numerical Analysis · Mathematics 2023-12-06 Yonglin Li , Haijun Wu

A parallel dispersive finite-difference time-domain (FDTD) method for the modeling of three-dimensional (3-D) electromagnetic cloaking structures is presented in this paper. The permittivity and permeability of the cloak are mapped to the…

Computational Physics · Physics 2015-05-13 Yan Zhao , Yang Hao

In this paper, we propose Fourier pseudospectral methods to solve the variable-order space fractional wave equation and develop an accelerated matrix-free approach for its effective implementation. In constant-order cases, our methods can…

Numerical Analysis · Mathematics 2024-02-06 Yanzhi Zhang , Xiaofei Zhao , Shiping Zhou

Modeling spectral line profiles taking frequency redistribution effects into account is a notoriously challenging problem from the computational point of view, especially when polarization phenomena (atomic polarization and polarized…

Solar and Stellar Astrophysics · Physics 2021-01-04 A. Paganini , B. Hashemi , E. Alsina Ballester , L. Belluzzi

We discuss studies of polarization in astrophysical masers with particular emphasis on the case where the Zeeman splitting is small compared to the Doppler profile, resulting in a blend of the transitions between magnetic substates. A…

Instrumentation and Methods for Astrophysics · Physics 2023-02-08 Taylor L. Tobin , Malcolm D. Gray , Athol J. Kemball

In this note we consider the Fourier expansion of the Ferrers function P of the first kind. We determine its mode of convergence.

Classical Analysis and ODEs · Mathematics 2021-09-02 Hans Volkmer

We propose a new model reduction framework for problems that exhibit transport phenomena. As in the moving finite element method (MFEM), our method employs time-dependent transformation operators and, especially, generalizes MFEM to…

Numerical Analysis · Mathematics 2020-10-30 Felix Black , Philipp Schulze , Benjamin Unger

Solving high-dimensional Fokker-Planck (FP) equations is a challenge in computational physics and stochastic dynamics, due to the curse of dimensionality (CoD) and unbounded domains. Existing deep learning approaches, such as…

Computational Physics · Physics 2026-03-25 Xiaolong Wu , Qifeng Liao