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In this paper we the formulation of inverse problems as constrained minimization problems and their iterative solution by gradient or Newton type. We carry out a convergence analysis in the sense of regularization methods and discuss…

Numerical Analysis · Mathematics 2021-01-15 Barbara Kaltenbacher , Kha Van Huynh

A Coefficient Inverse Problem for the radiative transport equation is considered. The globally convergent numerical method, the so-called convexification, is developed. For the first time, the viscosity solution is considered for a boundary…

Numerical Analysis · Mathematics 2023-03-17 Michael V. Klibanov , Jingzhi Li , Zhipeng Yang

The gyro-resonant cosmic-ray (CR) streaming instability is believed to play a crucial role in CR transport, leading to growth of Alfv\'en waves at small scales that scatter CRs, and impacts the interaction of CRs with the ISM on large…

High Energy Astrophysical Phenomena · Physics 2019-05-15 Xue-Ning Bai , Eve C. Ostriker , Illya Plotnikov , James M. Stone

The problem of cosmic-ray scattering in the turbulent electromagnetic fields of the interstellar medium and the solar wind is of great importance due to the variety of applications of the resulting diffusion coefficients. Examples are…

High Energy Astrophysical Phenomena · Physics 2015-05-20 R. C. Tautz

The problem of radio wave reflection from an optically thick plane monotonous layer of magnetized plasma is considered at present work. The plasma electron density irregularities are described by spatial spectrum of an arbitrary form. The…

Plasma Physics · Physics 2009-09-25 N. A. Zabotin , A. G. Bronin

In this paper, we study a fractional-order variant of the asymptotical regularization method, called {\it Fractional Asymptotical Regularization (FAR)}, for solving linear ill-posed operator equations in a Hilbert space setting. We assign…

Numerical Analysis · Mathematics 2019-07-16 Ye Zhang , Bernd Hofmann

We consider a perturbative approach to the Vlasov-Poisson system for cosmic structure formation that does not rely on any truncation of the momentum-cumulant hierarchy. The generally non-trivial linear solution is computed by solving a…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-14 Hannes Heisler , Marvin Sipp , Matthias Bartelmann

In this article, we establish a class of new accelerated modulus-based iteration methods for solving the linear complementarity problem. When the system matrix is an $H_+$-matrix, we present appropriate criteria for the convergence…

Optimization and Control · Mathematics 2023-05-05 Bharat Kumar , Deepmala , A. K. Das

The second-order cone linear complementarity problem (SOCLCP) is a generalization of the classical linear complementarity problem. It has been known that SOCLCP, with the globally uniquely solvable property, is essentially equivalent to a…

Numerical Analysis · Mathematics 2020-11-18 Yiding Lin , Xiang Wang , Leihong Zhang

We consider the propagation of galactic cosmic rays under assumption that the interstellar medium is a fractal one. An anomalous diffusion equation in terms of fractional derivatives is used to describe of cosmic ray propagation. The…

Astrophysics · Physics 2007-05-23 A. A. Lagutin , V. V. Uchaikin

We study nonlinear stability of spatially homogeneous oscillations in reaction-diffusion systems. Assuming absence of unstable linear modes and linear diffusive behavior for the neutral phase, we prove that spatially localized perturbations…

Analysis of PDEs · Mathematics 2008-07-01 Thierry Gallay , Arnd Scheel

Recently, Zhang & Liu (2024) proposed a turbulent convection model for multiscale anisotropies of cosmic rays (CRs), with an assumption of isotropic diffusion such that the anisotropies are statistically isotropic. However, this assumption…

High Energy Astrophysical Phenomena · Physics 2025-06-26 Yiran Zhang , Siming Liu

We present a comprehensive analytical study of radiative transfer using the method of moments and include the effects of non-isotropic scattering in the coherent limit. Within this unified formalism, we derive the governing equations and…

Earth and Planetary Astrophysics · Physics 2015-06-19 Kevin Heng , João M. Mendonça , Jae-Min Lee

A novel method to solve inverse problems for the wave equation is introduced. The method is a combination of the boundary control method and an iterative time reversal scheme, leading to adaptive imaging of coefficient functions of the wave…

Analysis of PDEs · Mathematics 2007-05-23 Kenrick Bingham , Yaroslav Kurylev , Matti Lassas , Samuli Siltanen

An approximate method is proposed for the recovery of a compactly supported spherically-symmetric potential from the set of fixed-energy phase-shifts known for all angular momenta. The method reduces the inverse scattering problem to a…

Mathematical Physics · Physics 2016-09-07 A. G. Ramm , W. Scheid

Cosmic rays (CRs) heavily impact the chemistry and physics of cold and dense star-forming regions. However, characterising their ionisation rate is still challenging from an observational point of view. In the past, a few analytical…

Astrophysics of Galaxies · Physics 2024-02-19 E. Redaelli , S. Bovino , A. Lupi , T. Grassi , D. Gaete-Espinoza , G. Sabatini , P. Caselli

In this paper, a class of smoothing modulus-based iterative method was presented for solving implicit complementarity problems. The main idea was to transform the implicit complementarity problem into an equivalent implicit fixed-point…

Numerical Analysis · Mathematics 2023-06-09 Cong Guo , Chenliang Li , Tao Luo

We present results for r-modes of relativistic nonbarotropic stars. We show that the main differential equation, which is formally singular at lowest order in the slow-rotation expansion, can be regularized if one considers the initial…

General Relativity and Quantum Cosmology · Physics 2009-11-07 K. H. Lockitch , N. Andersson , A. L. Watts

We introduce a (linear) positive and asymptotic preserving method or solving the one-group radiation transport equation. The approximation in space is discretization agnostic: the space approximation can be done with continuous or…

Numerical Analysis · Mathematics 2019-05-10 Jean-Luc Guermond , Bojan Popov , Jean Ragusa

This study explores the use of fractional calculus as a possible tool to model wave propagation in complex, heterogeneous media. We illustrate the methodology by focusing on elastic wave propagation in a one-dimensional periodic rod. The…

Classical Physics · Physics 2018-12-05 John Hollkamp , Mihir Sen , Fabio Semperlotti
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