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Current strategies for designing tunable locally resonant metamaterials are based on tuning the stiffness of the resonator; however, this approach presents a major shortcoming as the effective mass density is constant at high frequency.…

Applied Physics · Physics 2018-07-04 Quan Zhang , Kai Zhang , Gengkai Hu

Anomalous relaxation and diffusion processes have been widely characterized by fractional derivative models, where the definition of the fractional-order derivative remains a historical debate due to the singular memory kernel that…

Statistical Mechanics · Physics 2016-06-17 HongGuang Sun , Xiaoxiao Hao , Yong Zhang , Dumitru Baleanu

Unidirectional pulse propagation equations [UPPE, Phys. Rev. E 70, 036604 (2004)] have provided a theoretical underpinning for computer-aided investigations into dynamics of high-power ultrashort laser pulses and have been successfully…

Optics · Physics 2012-10-02 J. Andreasen , M. Kolesik

Diffusion MRI is a neuroimaging technique measuring the anatomical structure of tissues. Using diffusion MRI to construct the connections of tissues, known as fiber tracking, is one of the most important uses of diffusion MRI. Many…

Methodology · Statistics 2019-06-18 Zhou Lan , Brian J Reich

We consider an undetermined coefficient inverse problem for a nonlinear partial differential equation describing high intensity ultrasound propagation as widely used in medical imaging and therapy. The usual nonlinear term in the standard…

Numerical Analysis · Mathematics 2022-04-13 Barbara Kaltenbacher , William Rundell

We investigate the behavior of the time derivatives of the solution to a linear time-fractional, advection-diffusion-reaction equation, allowing space- and time-dependent coefficients as well as initial data that may have low regularity.…

Analysis of PDEs · Mathematics 2020-03-24 William McLean , Kassem Mustapha , Raed Ali , Omar M. Knio

Based on the notion of a construction process consisting of the stepwise addition of particles to the pure fluid, a discrete model for the apparent viscosity as well as for the maximum packing fraction of polydisperse suspensions of…

Fluid Dynamics · Physics 2014-02-28 Aaron Dörr , Amsini Sadiki , Amirfarhang Mehdizadeh

This paper develops a fractional stochastic partial differential equation (SPDE) to model the evolution of a random tangent vector field on the unit sphere. The SPDE is governed by a fractional diffusion operator to model the L\'{e}vy-type…

Probability · Mathematics 2024-01-15 Vo V. Anh , Andriy Olenko , Yu Guang Wang

Acoustic wave propagation in a one-dimensional waveguide connected with Helmholtz resonators is studied numerically. Finite amplitude waves and viscous boundary layers are considered. The model consists of two coupled evolution equations: a…

Classical Physics · Physics 2015-06-16 Bruno Lombard , Jean-François Mercier

Mathematical models describing the spatial spreading and invasion of populations of biological cells are often developed in a continuum modelling framework using reaction-diffusion equations. While continuum models based on linear diffusion…

Cellular Automata and Lattice Gases · Physics 2024-01-23 Matthew J Simpson , Keeley M Murphy , Scott W McCue , Pascal R Buenzli

We discuss a generalisation of fractional linear viscoelasticity based on Scarpi's approach to variable-order fractional calculus. After reviewing the general mathematical framework, we introduce the variable-order fractional Maxwell model…

Mathematical Physics · Physics 2023-11-29 A. Giusti , I. Colombaro , R. Garra , R. Garrappa , A. Mentrelli

We analyze a system of nonlinear stochastic partial differential equations (SPDEs) of mixed elliptic-parabolic type that models the propagation of electric signals and their effect on the deformation of cardiac tissue. The system governs…

Analysis of PDEs · Mathematics 2024-05-29 Mostafa Bendahmane , Kenneth H. Karlsen , Fatima Mroue

The frequency-dependent conductivity is studied for both the one-dimensional Hubbard model and a model of spinless fermions, using a selection rule, the Bethe ansatz energy eigenstates, and conformal invariance. For densities where the…

Condensed Matter · Physics 2007-05-23 J. M. P. Carmelo , P. D. Sacramento , N. M. R. Peres , D. Baeriswyl

We study the wave propagation in nonlinear electrodynamical models. Particular attention is paid to the derivation and the analysis of the Fresnel equation for the wave covectors. For the class of general nonlinear Lagrangian models, we…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Yuri N. Obukhov , Guillermo F. Rubilar

Anomalous heat diffusion is investigated for biological tissues displaying a fractal structure and long-term thermal memory, which is modeled via a fractional derivative. For increasing values of the fractional derivation order, the tissue…

Biological Physics · Physics 2025-07-15 Sébastien Fumeron , Malte Henkel , Alexander López

The characteristic impedance and the propagation coefficient are among the most important parameters for evaluating the acoustic performance of porous materials. This work investigates the influence of cylindrical modes in an impermeable…

Classical Physics · Physics 2026-05-19 Ziqi Chen , Ning Xiang

Diffusion (score-based) generative models have been widely used for modeling various types of complex data, including images, audios, and point clouds. Recently, the deep connection between forward-backward stochastic differential equations…

Machine Learning · Computer Science 2022-06-22 Weitao Du , Tao Yang , He Zhang , Yuanqi Du

The aim of this paper is first to review the derivation of a model describing the propagation of an optical wave in a photorefractive medium and to present various mathematical results on this model: Cauchy problem, solitary waves.

Analysis of PDEs · Mathematics 2007-12-03 Brigitte Bidégaray-Fesquet , Jean-Claude Saut

We derive the nonlinear fractional surface wave equation that governs compression waves at an interface that is coupled to a viscous bulk medium. The fractional character of the differential equation comes from the fact that the effective…

Fluid Dynamics · Physics 2017-11-29 Julian Kappler , Shamit Shrivastava , Matthias F. Schneider , Roland R. Netz

The aim of this paper is to provide a fractional generalization of the Gompertz law via a Caputo-like definition of fractional derivative of a function with respect to another function. In particular, we observe that the model presented…

Biological Physics · Physics 2019-03-26 Luigi Frunzo , Roberto Garra , Andrea Giusti , Vincenzo Luongo