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Johan Thim

Associate Professor

Analysis and partial differential equations

My main area of research is analysis and partial differential equations, in particular on domains with minimal smoothness assumptions.

The aim is to develop asymptotic methods for dealing with nonsmooth domains when solving partial differential equations. The study of regularity properties of solutions is a central problem in PDE theory, and developing tools is very important since not much is known for nonsmooth domains. I also have a large interest in mathemical history of the more modern type (my master's thesis dealt with the history of continuous nowhere differentiable functions). Some of the topics I'm currently working on includes the following.

  • Local estimates for Riesz potentials on nonsmooth surfaces.
  • Local estimates for solutions to elliptic equations near bad points at the boundary; asymptotic methods.
  • Hadamard type asymptotics for eigenvalues of elliptic operators under domain perturbations.
  • Continuous nowhere differentiable functions (historical).

Publications

2026

Jean Pierre Ngendahayo, Minani Froduald, Johan Thim, Fredrik Berntsson (2026) Solving an inverse heat conduction problem with phase transitions using Tikhonov regularization RESEARCH IN MATHEMATICS, Vol. 13, Article 2670816 (Article in journal) https://dx.doi.org/10.1080/27684830.2026.2670816

2025

J. P. Ngendahayo, F. Minani, Johan Thim, Fredrik Berntsson (2025) Convergence Analysis of Iterative Tikhonov Regularization Applied to an Inverse Heat Conduction Problem International Journal of Applied and Computational Mathematics, Vol. 11, Article 149 (Article in journal) https://dx.doi.org/10.1007/s40819-025-01972-0

2020

Vladimir Kozlov, Johan Thim (2020) Hadamard asymptotics for eigenvalues of the Dirichlet Laplacian Journal des Mathématiques Pures et Appliquées, Vol. 140, p. 67-88 (Article in journal) https://dx.doi.org/10.1016/j.matpur.2020.06.002

2017

Fredrik Berntsson, Anna Orlof, Johan Thim (2017) Error Estimation for Eigenvalues of Unbounded Linear Operators and an Application to Energy Levels in Graphene Quantum Dots Numerical Functional Analysis and Optimization, Vol. 38, p. 293-305 (Article in journal) https://dx.doi.org/10.1080/01630563.2017.1279176

2016

Vladimir Kozlov, Johan Thim (2016) Hadamard type asymptotics for eigenvalues of the Neumann problem for elliptic operators Journal of Spectral Theory, Vol. 6, p. 99-135 (Article in journal) https://dx.doi.org/10.4171/JST/120

Education

Organisation