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Motivated by experimental studies on the anomalous diffusion of biological populations, we introduce a nonlocal differential operator which can be interpreted as the spectral square root of the Laplacian in bounded domains with Neumann…

Analysis of PDEs · Mathematics 2012-08-03 Eugenio Montefusco , Benedetta Pellacci , Gianmaria Verzini

We consider inverse problems for the first and half order time fractional equation. We establish the stability estimates of Lipschitz type in inverse source and inverse coefficient problems by means of the Carleman estimates.

Analysis of PDEs · Mathematics 2018-12-27 Atsushi Kawamoto , Manabu Machida

This paper investigates an inverse boundary value problem for a semilinear strongly damped wave equation with Dirichlet boundary conditions in Sobolev spaces of functions bounded in time on $\R$, including periodic and almost periodic…

Analysis of PDEs · Mathematics 2026-04-15 Irina Kmit , Nataliya Protsakh , Viktor Tkachenko

We consider the first and half order time fractional equation with the zero initial condition. We investigate an inverse source problem of determining the time-independent source factor by the data at an arbitrarily fixed time and we…

Analysis of PDEs · Mathematics 2016-11-17 Atsushi Kawamoto

We consider an initial-boundary value problem for the time-fractional diffusion equation. We prove the equivalence of two notions of weak solutions, viscosity solutions and distributional solutions.

Analysis of PDEs · Mathematics 2021-08-26 Yoshikazu Giga , Hiroyoshi Mitake , Shoichi Sato

There has been considerable recent study in "sub-diffusion" models that replace the standard parabolic equation model by a one with a fractional derivative in the time variable. There are many ways to look at this newer approach and one…

Analysis of PDEs · Mathematics 2019-04-08 William Rundell , Zhidong Zhang

In this work, an inverse problem in the fractional diffusion equation with random source is considered. Statistical moments are used of the realizations of single point observation $u(x_0,t,\omega).$ We build the representation of the…

Analysis of PDEs · Mathematics 2019-11-04 Chan Liu , Jin Wen , Zhidong Zhang

Solutions of the Dirichlet and Robin boundary value problems for the multi-term variable-distributed order diffusion equation are studied. A priori estimates for the corresponding differential and difference problems are obtained by using…

Numerical Analysis · Mathematics 2014-01-31 A. A. Alikhanov

A class of inverse problems for restoring the right-hand side of a parabolic equation for a large class of positive operators with discrete spectrum is considered. The results on existence and uniqueness of solutions of these problems as…

Analysis of PDEs · Mathematics 2019-11-12 Michael Ruzhansky , Niyaz Tokmagambetov , Berikbol T. Torebek

This work considers the time-domain fluorescence diffuse optical tomography (FDOT). We recover the distribution of fluorophores in biological tissue by the boundary measurements. With the Laplace transform and the knowledge of complex…

Analysis of PDEs · Mathematics 2022-09-14 Chunlong Sun , Zhidong Zhang

We prove the uniqueness in determining a spatially varying zeroth-order coefficient of a one-dimensional time-fractional diffusion equation by initial value and Cauchy data at one end point of the spatial interval.

Analysis of PDEs · Mathematics 2024-09-04 Oleg Imanuvilov , Kazufumi Ito , Masahiro Yamamoto

This paper investigates the initial-boundary value problem for weakly coupled systems of time-fractional subdiffusion equations with spatially and temporally varying coupling coefficients. By combining the energy method with the coercivity…

Analysis of PDEs · Mathematics 2025-10-16 Zhiyuan Li , Yikan Liu , Kazuma Wada

In this article, we consider the space-time fractional (nonlocal) equation characterizing the so-called "double-scale" anomalous diffusion $$\partial_t^\beta u(t, x) = -(-\Delta)^{\alpha/2}u(t,x) - (-\Delta)^{\gamma/2}u(t,x) \ \ t> 0, \…

Analysis of PDEs · Mathematics 2019-12-18 Ngartelbaye Guerngar , Erkan Nane , Ramazan Tinatztepe , Suleyman Ulusoy , Hans Werner Van Wyk

We study waves in a rod of finite length with a viscoelastic constitutive equation of fractional distributed-order type for the special choice of weight functions. Prescribing boundary conditions on displacement, we obtain case…

Mathematical Physics · Physics 2011-01-10 Teodor M. Atanackovic , Stevan Pilipovic , Dusan Zorica

The work is devoted to the study of the inverse problem of determining the right-hand side of a nonlinear subdiffusion equation with a Caputo derivative with respect to time. Nonlinearity of the equation means that the right-hand side of…

Analysis of PDEs · Mathematics 2025-06-16 R. R. Ashurov , O. T. Mukhiddinova

We study the time-harmonic scattering by a heterogeneous object covered with a thin layer of randomly distributed sound-soft nanoparticles. The size of the particles, their distance between each other and the layer's thickness are all of…

Analysis of PDEs · Mathematics 2026-01-13 Amandine Boucart , Sonia Fliss , Laure Giovangigli

We investigate evolution equations for anomalous diffusion employing fractional derivatives in space and time. Linkage between the space-time variables leads to a new type of fractional derivative operator. Fractional diffusion equations…

Mathematical Physics · Physics 2007-05-23 Andrzej J. Turski , Barbara Atamaniuk , Ewa Turska

In this article, we consider the diffusion equation with multi-term time-fractional derivatives. We first derive that the solution is positive when the source term is nonpositive by a subordination principle for the solution. As an…

Analysis of PDEs · Mathematics 2021-06-25 Xiaona Yang , Zhiyuan Li

We determine the space-dependent source term for a two-parameter fractional diffusion problem subject to nonlocal non-self-adjoint boundary conditions and two local time-distinct datum. A bi-orthogonal pair of bases is used to construct a…

Classical Analysis and ODEs · Mathematics 2016-04-26 Khaled M. Furati , Olaniyi S. Iyiola , Kassem Mustapha

In this paper, we investigate the inverse problem of determining an unknown time-dependent source term in a semilinear pseudo-parabolic equation with variable coefficients and a Dirichlet boundary condition. The unknown source term is…

Analysis of PDEs · Mathematics 2026-02-19 Karel Van Bockstal , Khonatbek Khompysh , Arshyn Altybay