Browsing NTNU Open by Author "Ringholm, Torbjørn"
Now showing items 1-7 of 7
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Adaptive energy preserving methods for partial differential equations
Eidnes, Sølve; Owren, Brynjulf; Ringholm, Torbjørn (Journal article; Peer reviewed, 2017)A framework for constructing integral preserving numerical schemes for time-dependent partial differential equations on non-uniform grids is presented. The approach can be used with both finite difference and partition of ... -
Boundary determination for hybrid imaging from a single measurement
Brander, Tommi; Ringholm, Torbjørn (Journal article; Peer reviewed, 2024)We recover the conductivity σ at the boundary of a domain from a combination of Dirichlet and Neumann boundary data and generalized power/current density data at the boundary, from a single quite arbitrary set of data, in ... -
Discrete gradient methods in image processing and partial differential equations on moving meshes
Ringholm, Torbjørn (Doctoral theses at NTNU;2018:235, Doctoral thesis, 2018) -
Dissipative numerical schemes on Riemannian manifolds with applications to gradient flows
Celledoni, Elena; Eidnes, Sølve; Owren, Brynjulf; Ringholm, Torbjørn (Journal article; Peer reviewed, 2018)This paper concerns an extension of discrete gradient methods to finite-dimensional Riemannian manifolds termed discrete Riemannian gradients, and their application to dissipative ordinary differential equations. This ... -
Energy preserving methods on Riemannian manifolds
Celledoni, Elena; Eidnes, Sølve; Owren, Brynjulf; Ringholm, Torbjørn (Journal article, 2018)The energy preserving discrete gradient methods are generalized to finite-dimensional Riemannian manifolds by definition of a discrete approximation to the Riemannian gradient, a retraction, and a coordinate center function. ... -
Target Depth Estimation Using Hull Mounted Active Sonar
Ringholm, Torbjørn (Master thesis, 2014)High false alarm rates are a problem in anti-submarine warfare in littoral waters using active broadband sonar. Automatic classification algorithms may help combat this problem by filtering out detections due to non-threatening ... -
Variational image regularization with Euler's elastica using a discrete gradient scheme
Ringholm, Torbjørn; Lazic, Jasmina; Schönlieb, Carola-Bibiane (Journal article; Peer reviewed, 2018)This paper concerns an optimization algorithm for unconstrained nonconvex problems where the objective function has sparse connections between the unknowns. The algorithm is based on applying a dissipation preserving ...