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As an extension of isotropic Gaussian random fields and Q-Wiener processes on d-dimensional spheres, isotropic Q-fractional Brownian motion is introduced and sample H\"older regularity in space-time is shown depending on the regularity of…

Probability · Mathematics 2025-05-23 Annika Lang , Björn Müller

The propagation of cosmic rays (CRs) in turbulent interstellar magnetic fields is typically described as a spatial diffusion process. This formalism predicts only a small deviation from an isotropic CR distribution in the form of a dipole…

High Energy Astrophysical Phenomena · Physics 2014-01-22 Markus Ahlers

We develop a technique for the construction of random fields on algebraic structures. We deal with two general situations: random fields on homogeneous spaces of a compact group and in the spin-line bundles of the 2-sphere. In particular,…

Probability · Mathematics 2015-01-29 Paolo Baldi , Maurizia Rossi

Isotropic Gaussian random fields on the sphere are characterized by Karhunen-Lo\`{e}ve expansions with respect to the spherical harmonic functions and the angular power spectrum. The smoothness of the covariance is connected to the decay of…

Probability · Mathematics 2015-10-26 Annika Lang , Christoph Schwab

Stochastic homogenization is achieved for a class of elliptic and parabolic equations describing the lifetime, in large domains, of stationary diffusion processes in random environment which are small, statistically isotropic perturbations…

Analysis of PDEs · Mathematics 2016-03-01 Benjamin J. Fehrman

Random fields on the sphere play a fundamental role in the natural sciences. This paper presents a simulation algorithm parenthetical to the spectral turning bands method used in Euclidean spaces, for simulating scalar- or vector-valued…

Statistics Theory · Mathematics 2020-03-31 Alfredo Alegría , Xavier Emery , Christian Lantuéjoul

We construct an integrable lattice model of classical interacting spins in discrete space-time, representing a discrete-time analogue of the lattice Landau-Lifshitz ferromagnet with uniaxial anisotropy. As an application we use this…

Statistical Mechanics · Physics 2026-01-09 Žiga Krajnik , Enej Ilievski , Tomaž Prosen , Vincent Pasquier

We propose a non-perturbative numerical approach to calculate the spectrum of a many-body Hamiltonian with time and momentum resolution by exactly recreating a scattering event using the time-dependent Schr\"odinger equation. Akin an actual…

Strongly Correlated Electrons · Physics 2021-01-04 Krissia Zawadzki , Luhang Yang , Adrian E. Feiguin

Modeling a precipitation field is challenging due to its intermittent and highly scale-dependent nature. Motivated by the features of high-frequency precipitation data from a network of rain gauges, we propose a threshold space-time $t$…

Applications · Statistics 2016-02-10 Ying Sun , Michael L. Stein

We study the representations of tensor random fields on the sphere basing on the theory of representations of the rotation group. Introducing specific components of a tensor field and imposing the conditions of weak isotropy and mean square…

Probability · Mathematics 2012-02-15 Nikolai Leonenko , Ludmila Sakhno

A method is presented for solving elastodynamic problems in radially inhomogeneous elastic materials with spherical anisotropy, i.e.\ materials such that $c_{ijkl}= c_{ijkl}(r)$ in a spherical coordinate system ${r,\theta,\phi}$. The time…

Materials Science · Physics 2011-12-26 A. N. Norris , A. L. Shuvalov

We study the problem of lateral diffusion on a static, quasi-planar surface generated by a stationary, ergodic random field possessing rapid small-scale spatial fluctuations. The aim is to study the effective behaviour of a particle…

Probability · Mathematics 2014-02-03 A. B. Duncan

Understanding the time scales for diffusive processes and their degree of anisotropy is essential for modelling cosmic-ray transport in turbulent magnetic fields. We show that the diffusion time scales are isotropic over a large range of…

High Energy Astrophysical Phenomena · Physics 2022-06-01 P. Reichherzer , J. Becker Tjus , E. G. Zweibel , L. Merten , M. J. Pueschel

Identifying an appropriate covariance function is one of the primary interests in spatial and spatio-temporal statistics because it allows researchers to analyze the dependence structure of the random process. For this purpose, spatial…

Methodology · Statistics 2025-02-04 Jongwook Kim , Chunfeng Huang , Nicholas Bussberg

Travel-time imaging problems seek to reconstruct an image of reflectivity of a scene by measuring travel time (and amplitude, phase) of electromagnetic or acoustic signals, such as radar and sonar. Multistatic, in this context, means that…

Analysis of PDEs · Mathematics 2026-02-05 Naeem Desai , Oliver Graham , Sean Holman , William R. B. Lionheart

In this paper, we focus on isotropic and stationary sphere-cross-time random fields. We first introduce the class of spherical functional autoregressive-moving average processes (SPHARMA), which extend in a natural way the spherical…

Statistics Theory · Mathematics 2020-09-29 Alessia Caponera

We compute the leading-order inertial corrections to the instantaneous force acting on a rigid body moving with a time-dependent slip velocity in a linear flow field, assuming that the variation of the undisturbed flow at the body scale is…

Fluid Dynamics · Physics 2025-10-01 Fabien Candelier , Bernhard Mehlig , Jacques Magnaudet

In this paper we have obtained cosmological models for the static spherically symmetric spacetime with charged anisotropic fluid distribution in (n+2)-dimensions in context of Rosen's Bimetric General Relativity (BGR). An exact solution is…

General Physics · Physics 2017-05-12 A. H. Hasmani , D. N. Pandya

We study the rotational dynamics of {\it inertial} disks and rods in three-dimensional, homogeneous isotropic turbulence. In particular, we show how the alignment and the decorrelation time-scales of such spheroids depend, critically, on…

Fluid Dynamics · Physics 2018-08-07 Amal Roy , Anupam Gupta , Samriddhi Sankar Ray

This work introduces original explicit solutions for the elastic fields radiated by non-uniformly moving, straight, screw or edge dislocations in an isotropic medium, in the form of time-integral representations in which…

Classical Physics · Physics 2016-09-26 Markus Lazar , Yves-Patrick Pellegrini