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Fast, accurate, and stable computation of the Clebsch-Gordan (C-G) coefficients is always desirable, for example, in light scattering simulations, the translation of the multipole fields, quantum physics and chemistry. Current recursive…

Computational Physics · Physics 2020-08-26 Guanglang Xu

Some high-energy experiments have suffered from synchrotron-radiation background. As a measure, we have developed a new calculation method of synchrotron radiation based on a real beam orbit, aiming at quantitative estimations and the…

Accelerator Physics · Physics 2016-09-08 Tetsuo Abe , Hitoshi Yamamoto

Understanding the complex dynamics and structure of the upper solar atmosphere benefits strongly from the use of a combination of several diagnostics. Frequently, such diverse diagnostics can only be obtained from telescopes and/or…

Solar and Stellar Astrophysics · Physics 2019-11-13 J. de la Cruz Rodríguez

The classical Szeg\H{o}-Verblunsky theorem relates integrability of the logarithm of the absolutely continuous part of a probability measure on the circle to square summability of the sequence of recurrence coefficients for the orthogonal…

Functional Analysis · Mathematics 2022-02-22 Peter C. Gibson

We give a sharp polynomial bound on the number of Pollicott-Ruelle resonances. These resonances, which are complex numbers in the lower half-plane, appear in expansions of correlations for Anosov contact flows. The bounds follow the…

Spectral Theory · Mathematics 2019-02-20 Kiril Datchev , Semyon Dyatlov , Maciej Zworski

In this paper, we establish a new estimate (including lower and upper bounds) for an important quantity involved in the convergence analysis of smoothed aggregation algebraic multigrid methods. The new upper bound improves the existing…

Numerical Analysis · Mathematics 2019-03-19 Xuefeng Xu , Chen-Song Zhang

In this paper we consider the numerical solution of fractional differential equations. In particular, we study a step-by-step graded mesh procedure based on an expansion of the vector field using orthonormal Jacobi polynomials. Under mild…

Numerical Analysis · Mathematics 2024-04-09 L. Brugnano , K. Burrage , P. Burrage , F. Iavernaro

This paper is concerned with the efficient numerical computation of solutions to the 1D stationary Schr\"odinger equation in the semiclassical limit in the highly oscillatory regime. A previous approach to this problem based on explicitly…

Numerical Analysis · Mathematics 2019-11-05 A. Arnold , C. Klein. B. Ujvari

We develop a new numerical scheme for solving the radiative transfer equation in a spherically symmetric system. This scheme does not rely on any kind of diffusion approximation and it is accurate for optically thin, thick, and intermediate…

Instrumentation and Methods for Astrophysics · Physics 2018-05-31 Torsten Stamer , Shu-ichiro Inutsuka

Motivated by applications to acoustic imaging, the present work establishes a framework to analyze scattering for the one-dimensional wave, Helmholtz, Schr\"odinger and Riccati equations that allows for coefficients which are more singular…

Analysis of PDEs · Mathematics 2022-02-28 Peter C. Gibson

Spherical Whittle--Mat\'ern Gaussian random fields are considered as solutions to fractional elliptic stochastic partial differential equations on the sphere. Approximation is done with surface finite elements. While the non-fractional part…

Numerical Analysis · Mathematics 2023-12-06 Erik Jansson , Mihály Kovács , Annika Lang

In this paper we first establish global pointwise time-space estimates of the fundamental solution for Schr\"odinger equations, where the symbol of the spatial operator is a real non-degenerate elliptic polynomial. Then we use such…

Analysis of PDEs · Mathematics 2015-06-09 JinMyong Kim , Anton Arnold , Xiaohua Yao

In this paper a lower bound for solutions to the secular equation of the Schr\"odinger equation with basis functions discontinuous on boundaries of divided regions is given. If the functions do not have the discontinuity, the bound reduces…

Analysis of PDEs · Mathematics 2023-12-08 Sohei Ashida

A discrete spherical harmonics method is developed for the radiative transfer problem in inhomogeneous polarized planar atmosphere illuminated at the top by a collimated sunlight while the bottom reflects the radiation. The method expands…

Instrumentation and Methods for Astrophysics · Physics 2018-02-07 Romuald Tapimo , Hervé Thierry Tagne Kamdem , David Yemele

It is known that convergence of l.s.b. closed symmetric sesquilinear forms implies norm resolvent convergence of the associated self-adjoint operators and this in turn convergence of discrete spectra. In this paper in both cases sharp…

Mathematical Physics · Physics 2017-12-12 Johannes F. Brasche , Robert Fulsche

We employ a lattice Boltzmann method to compute the acoustic radiation force produced by standing waves on a compressible object. Instead of simulating the fluid mechanics equations directly, the proposed method uses a lattice Boltzmann…

Fluid Dynamics · Physics 2024-08-15 E. Castro-Avila , P. Malgaretti , J. Harting , J. D. Muñoz

A theory of Clebsch-Gordan coefficients for $SL(2, C)$ is given using only rational numbers. Features include orthogonality relations, recurrence relations, and Regge's symmetry group. Results follow from elementary representation theory…

Representation Theory · Mathematics 2021-10-28 Robert W. Donley , Won Geun Kim

The Kirchhoff approximation (K-A) to calculate the acoustic backscattering of a complex structure can be evaluated using a discretized version of its surface (i.e. a $\textit{mesh}$). From the computational viewpoint, the most accesible…

Computational Physics · Physics 2019-12-04 Edmundo Lavia , Juan D. Gonzalez , Silvia Blanc

In the framework of mapped pseudospectral methods, we introduce a new polynomial-type mapping function in order to describe accurately the dynamics of systems developing almost singular structures. Using error criteria related to the…

Computational Physics · Physics 2008-10-21 Adrian Alexandrescu , Alfonso Bueno-Orovio , Jose R. Salgueiro , Victor M. Perez-Garcia

We consider the use of rational basis functions to compute the scattering and inverse scattering transforms associated with the AKNS system. The proposed numerical forward scattering transform computes the solution of the AKNS system that…

Numerical Analysis · Mathematics 2021-07-02 Thomas Trogdon