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As the most significant difference from parabolic equations, long-time or short-time behavior of solutions to time-fractional evolution equations is dominated by the fractional orders, whose unique determination has been frequently…

Analysis of PDEs · Mathematics 2023-01-03 Yikan Liu , Masahiro Yamamoto

Real-world data generation often involves complex inter-dependencies among instances, violating the IID-data hypothesis of standard learning paradigms and posing a challenge for uncovering the geometric structures for learning desired…

Machine Learning · Computer Science 2023-05-30 Qitian Wu , Chenxiao Yang , Wentao Zhao , Yixuan He , David Wipf , Junchi Yan

This paper deals with fractional differential equations, with dependence on a Caputo fractional derivative of real order. The goal is to show, based on concrete examples and experimental data from several experiments, that fractional…

General Mathematics · Mathematics 2016-11-03 Ricardo Almeida , Nuno R. O. Bastos , M. Teresa T. Monteiro

We construct new, efficient, and accurate high-order finite differencing operators which satisfy summation by parts. Since these operators are not uniquely defined, we consider several optimization criteria: minimizing the bandwidth, the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Peter Diener , Ernst Nils Dorband , Erik Schnetter , Manuel Tiglio

We investigate the properties of some recently developed variable-order differential operators involving order transition functions of exponential type. Since the characterisation of such operators is performed in the Laplace domain it is…

Numerical Analysis · Mathematics 2023-09-19 Roberto Garrappa , Andrea Giusti

Some fractional and anomalous diffusions are driven by equations involving fractional derivatives in both time and space. Such diffusions are processes with randomly varying times. In representing the solutions to those diffusions, the…

Probability · Mathematics 2012-06-05 Mirko D'Ovidio

Fractional operators play an important role in modeling nonlocal phenomena and problems involving coarse-grained and fractal spaces. The fractional calculus of variations with functionals depending on derivatives and/or integrals of…

Optimization and Control · Mathematics 2014-06-23 Matheus J. Lazo , Delfim F. M. Torres

An optical flow variational model is proposed for a sequence of images defined on a domain in $\mathbb{R}^2$. We introduce a regularization term given by the $L^1$ norm of a fractional differential operator. To solve the minimization…

Numerical Analysis · Mathematics 2015-12-07 Somayeh Gh. Bardeji , Isabel N. Figueiredo , Ercília Sousa

We present a finite element scheme for fractional diffusion problems with varying diffusivity and fractional order. We consider a symmetric integral form of these nonlocal equations defined on general geometries and in arbitrary bounded…

Numerical Analysis · Mathematics 2023-06-28 Wenyu Lei , George Turkiyyah , Omar Knio

We study a fractional differentiation operator for functions on the conjugate space to an infinite extension of a local field of zero characteristic which is a union of an increasing sequence of finite extensions. In particular, a…

Functional Analysis · Mathematics 2007-05-23 Anatoly N. Kochubei

The study of fractional order differential operators is receiving renewed attention in many scientific fields. In order to accommodate researchers doing work in these areas, there is a need for highly scalable numerical methods for solving…

Distributed, Parallel, and Cluster Computing · Computer Science 2019-11-28 Max Carlson , Robert M. Kirby , Hari Sundar

We propose a new class of semi-implicit methods for solving nonlinear fractional differential equations and study their stability. Several versions of our new schemes are proved to be unconditionally stable by choosing suitable parameters.…

Numerical Analysis · Mathematics 2018-08-14 Fanhai Zeng , Ian Turner , Kevin Burrage , George Em Karniadakis

We develop an operator-theoretical method for the analysis on well posedness of partial differential equations that can be modeled in the form \begin{equation*} \left\{ \begin{array}{rll} \Delta^{\alpha} u(n) &= Au(n+2) + f(n,u(n)), \quad n…

Analysis of PDEs · Mathematics 2016-06-17 Luciano Abadias , Carlos Lizama , Pedro J. Miana , M. Pilar Velasco

The survey is devoted to numerical solution of the fractional equation $A^\alpha u=f$, $0 < \alpha <1$, where $A$ is a symmetric positive definite operator corresponding to a second order elliptic boundary value problem in a bounded domain…

Numerical Analysis · Mathematics 2020-10-07 Stanislav Harizanov , Raytcho Lazarov , Svetozar Margenov

In this note, a numerical method based on finite differences to solve a class of nonlinear advection-diffusion fractional differential equation is proposed. The fractional operator considered here is the fractional Riemann-Liouville…

Analysis of PDEs · Mathematics 2020-10-09 Jocemar Q. Chagas , Giuliano G. La Guardia , Ervin K. Lenzi

A finite difference numerical method is investigated for fractional order diffusion problems in one space dimension. For this, a mathematical model is developed to incorporate homogeneous Dirichlet and Neumann type boundary conditions. The…

Numerical Analysis · Mathematics 2014-11-07 Béla J. Szekeres , Ferenc Izsák

After reviewing the problematic behavior of some previously suggested finite interval spatial operators of the symmetric Riesz type, we create a wish list leading toward a new spatial operator suitable to use in the space-time fractional…

Fluid Dynamics · Physics 2015-05-14 P. P. Valkó , X. H. Zhang

The modulating functions method has been used for the identification of linear and nonlinear systems. In this paper, we generalize this method to the on-line identification of fractional order systems based on the Riemann-Liouville…

Numerical Analysis · Mathematics 2013-03-18 Da-Yan Liu , Taous-Meriem Laleg-Kirati , Olivier Gibaru , Wilfrid Perruquetti

In this paper, a diffusion operator including conformable fractional derivatives of order {\alpha} ({\alpha} in (0,1)) is considered. The asymptotics of the eigenvalues, eigenfunctions and nodal points of the operator are obtained.…

Spectral Theory · Mathematics 2023-01-03 Yaşar Çakmak

In this paper, we are interested in the study of a problem with fractional derivatives having boundary conditions of integral types. The problem represents a Caputo type advection-diffusion equation where the fractional order derivative…

Numerical Analysis · Mathematics 2021-02-23 Saadoune Brahimi , Ahcene Merad , Adem Kilicman