21 citations · 42 across the 24 of their papers we have counts for
27 papers
Beyond Consistent Scenarios: Deriving Indirect Influence, Transition Resistance, and Adjustment Dynamics
Andrew G. Ross, Julia Gershenzon, Andreas Kleefeld
Assessments of structural change and economic transition dynamics, such as those arising in the energy transition, depend on internally consistent qualitative scenarios specifying…
Factorization method for a simply supported obstacle from point source measurements via far--field transformation
Isaac Harris, Andreas Kleefeld
We consider an inverse shape problem for recovering an unknown simply supported obstacle in two dimensions from near--field point--source measurements for the biharmonic Helmholtz…
Bifurcations in Interior Transmission Eigenvalues: Theory and Computation
Davide Pradovera, Alessandro Borghi, Lukas Pieronek +1
The interior transmission eigenvalue problem (ITP) plays a central role in inverse scattering theory and in the spectral analysis of inhomogeneous media. Despite its smooth depende…
Analysis of the transmission eigenvalue problem for biharmonic scattering considering penetrable scatterers
Rafael Ceja Ayala, Isaac Harris, Andreas Kleefeld
In this paper, we provide an analytical study of the transmission eigenvalue problem in the context of biharmonic scattering with a penetrable obstacle. We will assume that the und…
Existence of transmission eigenvalues for biharmonic scattering by a clamped planar region
Isaac Harris, Andreas Kleefeld, Heejin Lee
In this paper, we study the so-called clamped transmission eigenvalue problem. This is a new transmission eigenvalue problem that is derived from the scattering of an impenetrable…
Direct and inverse scattering for an isotropic medium with a second-order boundary condition
Govanni Granados, Isaac Harris, Andreas Kleefeld
We consider the direct and inverse scattering problem for a penetrable, isotropic obstacle with a second-order Robin boundary condition, which asymptotically models the delaminatio…
On the transmission eigenvalues for scattering by a clamped planar region
Isaac Harris, Heejin Lee, Andreas Kleefeld
In this paper, we consider a new transmission eigenvalue problem derived from the scattering by a clamped cavity in a thin elastic material. Scattering in a thin elastic material c…
Two direct sampling methods for an anisotropic scatterer with a conductive boundary
Isaac Harris, Victor Hughes, Andreas Kleefeld
In this paper, we consider the inverse scattering problem associated with an anisotropic medium with a conductive boundary condition. We will assume that the corresponding far--fie…
Matrix-Valued LogSumExp Approximation for Colour Morphology
Marvin Kahra, Michael Breuß, Andreas Kleefeld +1
Mathematical morphology is a part of image processing that uses a window that moves across the image to change certain pixels according to certain operations. The concepts of supre…
Sampling methods for recovering buried corroded boundaries from partial electrostatic Cauchy data
Isaac Harris, Andreas Kleefeld, Heejin Lee
We consider the inverse shape and parameter problem for detecting corrosion from partial boundary measurements. This problem models the non-destructive testing for a partially buri…
Inverse parameter and shape problem for an isotropic scatterer with two conductivity coefficients
Rafael Ceja Ayala, Isaac Harris, Andreas Kleefeld
In this paper, we consider the direct and inverse problem for isotropic scatterers with two conductive boundary conditions. First, we show the uniqueness for recovering the coeffic…
An Approach to Colour Morphological Supremum Formation using the LogSumExp Approximation
Marvin Kahra, Michael Breuß, Andreas Kleefeld +1
Mathematical morphology is a part of image processing that has proven to be fruitful for numerous applications. Two main operations in mathematical morphology are dilation and eros…
Comparing intrusive and non-intrusive polynomial chaos for a class of exponential time differencing schemes
Julian Clausnitzer, Andreas Kleefeld
We consider the numerical approximation of different ordinary differential equations (ODEs) and partial differential equations (PDEs) with periodic boundary conditions involving a…
A spectral Galerkin exponential Euler time-stepping scheme for parabolic SPDEs on two-dimensional domains with a C2-boundary
Julian Clausnitzer, Andreas Kleefeld
We consider the numerical approximation of second-order semi-linear parabolic stochastic partial differential equations interpreted in the mild sense which we solve on general two-…
Direct sampling method via Landweber iteration for an absorbing scatterer with a conductive boundary
Rafael Ceja Ayala, Isaac Harris, Andreas Kleefeld
In this paper, we consider the inverse shape problem of recovering isotropic scatterers with a conductive boundary condition. Here, we assume that the measured far-field data is kn…
Detecting and approximating decision boundaries in low dimensional spaces
Matthias Grajewski, Andreas Kleefeld
A method for detecting and approximating fault lines or surfaces, respectively, or decision curves in two and three dimensions with guaranteed accuracy is presented. Reformulated a…
Analysis of the transmission eigenvalue problem with two conductivity parameters
Rafael Ceja Ayala, Isaac Harris, Andreas Kleefeld +1
In this paper, we provide an analytical study of the transmission eigenvalue problem with two conductivity parameters. We will assume that the underlying physical model is given by…
On trajectories of complex-valued interior transmission eigenvalues
Lukas Pieronek, Andreas Kleefeld
This paper investigates properties of complex-valued eigenvalue trajectories for the interior transmission problem parametrized by the index of refraction for homogeneous media. Ou…
The hot spots conjecture can be false: Some numerical examples
Andreas Kleefeld
The hot spots conjecture is only known to be true for special geometries. It can be shown numerically that the hot spots conjecture can fail to be true for easy to construct bounde…
A second-order exponential time differencing scheme for non-linear reaction-diffusion systems with dimensional splitting
E. O. Asante-Asamani, A. Kleefeld, B. A. Wade
A second-order -stable exponential time-differencing (ETD) method is developed by combining an ETD scheme with approximating the matrix exponentials by rational functions having…
Elastic interior transmission eigenvalues and their computation via the method of fundamental solutions
Andreas Kleefeld, Lukas Pieronek
A stabilized version of the fundamental solution method to catch ill-conditioning effects is investigated with focus on the computation of complex-valued elastic interior transmiss…
Analysis of new direct sampling indicators for far-field measurements
Isaac Harris, Andreas Kleefeld
This article focuses on the analysis of three direct sampling indicators which can be used for recovering scatterers from the far-field pattern of time-harmonic acoustic measuremen…
Shape optimization for interior Neumann and transmission eigenvalues
Andreas Kleefeld
Shape optimization problems for interior eigenvalues is a very challenging task since already the computation of interior eigenvalues for a given shape is far from trivial. For exa…
Theoretical Foundation of the Weighted Laplace Inpainting Problem
Laurent Hoeltgen, Andreas Kleefeld, Isaac Harris +1
Laplace interpolation is a popular approach in image inpainting using partial differential equations. The classic approach considers the Laplace equation with mixed boundary condit…