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This article devotes to developing robust but simple correction techniques and efficient algorithms for a class of second-order time stepping methods, namely the shifted fractional trapezoidal rule (SFTR), for subdiffusion problems to…

Numerical Analysis · Mathematics 2020-10-26 Baoli Yin , Yang Liu , Hong Li , Zhimin Zhang

We consider the initial boundary value problem for the time-fractional diffusion equation with a homogeneous Dirichlet boundary condition and an inhomogeneous initial data $a(x)\in L^{2}(D)$ in a bounded domain $D\subset \mathbb{R}^d$ with…

Numerical Analysis · Mathematics 2020-02-19 Jiuhua Hu , Guanglian Li

This paper deals with the distributed order time-fractional diffusion equations with non-homogeneous Dirichlet (Nuemann) boundary condition. We first prove the wellposedness of the weak solution to the initial boundary value problem for the…

Analysis of PDEs · Mathematics 2018-08-13 Zhiyuan Li , Kenichi Fujishiro , Gongsheng Li

We consider an optimal control problem that entails the minimization of a nondifferentiable cost functional, fractional diffusion as state equation and constraints on the control variable. We provide existence, uniqueness and regularity…

Numerical Analysis · Mathematics 2017-04-05 Enrique Otárola , Abner J. Salgado

We discrete the ergodic semilinear stochastic partial differential equations in space dimension $d \leq 3$ with additive noise, spatially by a spectral Galerkin method and temporally by an exponential Euler scheme. It is shown that both the…

Numerical Analysis · Mathematics 2020-06-16 Ziheng Chen , Siqing Gan , Xiaojie Wang

We consider a discontinuous Galerkin method for the numerical solution of boundary value problems in two-dimensional domains with curved boundaries. A key challenge in this setting is the potential loss of convergence order due to…

Numerical Analysis · Mathematics 2026-01-16 Adérito Araújo , Milene Santos

We study solution techniques for an evolution equation involving second order derivative in time and the spectral fractional powers, of order $s \in (0,1)$, of symmetric, coercive, linear, elliptic, second-order operators in bounded domains…

Numerical Analysis · Mathematics 2018-06-18 Lehel Banjai , Enrique Otarola

The aim of this paper is to numerically solve a diffusion differential problem having time derivative of fractional order. To this end we propose a collocation-Galerkin method that uses the fractional splines as approximating functions. The…

Numerical Analysis · Mathematics 2022-04-27 Laura Pezza , Francesca Pitolli

In this article, the piecewise-linear finite element method (FEM) is applied to approximate the solution of time-fractional diffusion equations on bounded convex domains. Standard energy arguments do not provide satisfactory results for…

Numerical Analysis · Mathematics 2018-11-06 Samir Karaa , Kassem Mustapha , Amiya K. Pani

The discontinuous Galerkin dG method provides a robust and flexible technique for the time integration of fractional diffusion problems. However, a practical implementation uses coefficients defined by integrals that are not easily…

Numerical Analysis · Mathematics 2022-08-09 William McLean

Diffusion models, which convert noise into new data instances by learning to reverse a diffusion process, have become a cornerstone in contemporary generative modeling. In this work, we develop non-asymptotic convergence theory for a…

Machine Learning · Computer Science 2024-08-06 Gen Li , Yuting Wei , Yuejie Chi , Yuxin Chen

Anomalous diffusion is a phenomenon that cannot be modeled accurately by second-order diffusion equations, but is better described by fractional diffusion models. The nonlocal nature of the fractional diffusion operators makes substantially…

Numerical Analysis · Mathematics 2018-03-08 K. Mustapha , K. Furati , O. M. Knio , O. Le Maitre

In this paper, we consider a fast and second-order implicit difference method for approximation of a class of time-space fractional variable coefficients advection-diffusion equation. To begin with, we construct an implicit difference…

Numerical Analysis · Mathematics 2019-07-12 Yong-Liang Zhao , Ting-Zhu Huang , Xian-Ming Gu , Wei-Hua Luo

This paper provides the semi-discrete scheme by the central local discontinuous Galerkin method for space fractional diffusion equation on two sets of overlapping cells, and then we give the stability analysis and error estimates for the…

Numerical Analysis · Mathematics 2019-08-05 Jing Sun , Daxin Nie , Weihua Deng

We consider the Shallow Water equations in the supercritical and subcritical cases in one space variable,posed in a finite spatial interval with characteristic boundary conditions at the endpoints, which, as is well known, are…

Numerical Analysis · Mathematics 2016-03-01 D. C. Antonopoulos , V. A. Dougalis

We present a full space-time numerical solution of the advection-diffusion equation using a continuous Galerkin finite element method on conforming meshes. The Galerkin/least-square method is employed to ensure stability of the discrete…

Numerical Analysis · Mathematics 2024-11-25 Biswajit Khara , Kumar Saurabh , Robert Dyja , Anupam Sharma , Baskar Ganapathysubramanian

We consider a singularly perturbed time-dependent problem with a shift term in space. On appropriately defined layer adapted meshes of Dur\'{a}n- and S-type we derive a-priori error estimates for the stationary problem. Using a…

Numerical Analysis · Mathematics 2022-09-07 Mirjana Brdar , Sebastian Franz , Lars Ludwig , Hans-Görg Roos

This chapter reviews and compares discontinuous Galerkin time-stepping methods for the numerical approximation of second-order ordinary differential equations, particularly those stemming from space finite element discretization of wave…

Numerical Analysis · Mathematics 2025-05-12 Paola F. Antonietti , Alberto Artoni , Gabriele Ciaramella , Ilario Mazzieri

In this paper, we study numerical methods for the solution of partial differential equations on evolving surfaces. The evolving hypersurface in $\Bbb{R}^d$ defines a $d$-dimensional space-time manifold in the space-time continuum…

Numerical Analysis · Mathematics 2014-04-09 Maxim A. Olshanskii , Arnold Reusken , Xianmin Xu

In this paper, we present optimal error estimates of the local discontinuous Galerkin method with generalized numerical fluxes for one-dimensional nonlinear convection-diffusion systems. The upwind-biased flux with adjustable numerical…

Numerical Analysis · Mathematics 2022-09-09 Hongjuan Zhang , Boying Wu , Xiong Meng