Zobrazeno 1 - 10
of 150
pro vyhledávání: '"Valkonen, Tuomo"'
Autor:
Suonperä, Ensio, Valkonen, Tuomo
Bilevel optimisation is used in inverse problems for hyperparameter learning and experimental design. For instance, it can be used to find optimal regularisation parameters and forward operators, based on a set of training pairs. However, computation
Externí odkaz:
http://arxiv.org/abs/2408.08123
Online optimisation facilitates the solution of dynamic inverse problems, such as image stabilisation, fluid flow monitoring, and dynamic medical imaging. In this paper, we improve upon previous work on predictive online primal-dual methods on two fr
Externí odkaz:
http://arxiv.org/abs/2405.02497
Autor:
Valkonen, Tuomo
Publikováno v:
Journal of Nonsmooth Analysis and Optimization, Volume 4, Original research articles (September 21, 2023) jnsao:10433
Point source localisation is generally modelled as a Lasso-type problem on measures. However, optimisation methods in non-Hilbert spaces, such as the space of Radon measures, are much less developed than in Hilbert spaces. Most numerical algorithms f
Externí odkaz:
http://arxiv.org/abs/2212.02991
Autor:
Jensen, Bjørn, Valkonen, Tuomo
Publikováno v:
Computational Optimization and Applications (2024)
We introduce an efficient first-order primal-dual method for the solution of nonsmooth PDE-constrained optimization problems. We achieve this efficiency through not solving the PDE or its linearisation on each iteration of the optimization method. In
Externí odkaz:
http://arxiv.org/abs/2211.04807
Autor:
Suonperä, Ensio, Valkonen, Tuomo
Publikováno v:
Computational Optimization and Applications (2023)
We propose a new approach to solving bilevel optimization problems, intermediate between solving full-system optimality conditions with a Newton-type approach, and treating the inner problem as an implicit function. The overall idea is to solve the f
Externí odkaz:
http://arxiv.org/abs/2205.04862
Publikováno v:
Inverse Problems 38 065004 (2022)
In electrical impedance tomography, we aim to solve the conductivity within a target body through electrical measurements made on the surface of the target. This inverse conductivity problem is severely ill-posed, especially in real applications with
Externí odkaz:
http://arxiv.org/abs/2110.15697
Publikováno v:
Computer-aided Civil and Infrastructure Engineering 2021
Electrical resistance tomography (ERT) -based distributed surface sensing systems, or sensing skins, offer alternative sensing techniques for structural health monitoring, providing capabilities for distributed sensing of, for example, damage, strain
Externí odkaz:
http://arxiv.org/abs/2012.04588
Autor:
Valkonen, Tuomo
Publikováno v:
Inverse Problems 37 (2021), 045010
Regularisation theory in Banach spaces, and non--norm-squared regularisation even in finite dimensions, generally relies upon Bregman divergences to replace norm convergence. This is comparable to the extension of first-order optimisation methods to
Externí odkaz:
http://arxiv.org/abs/2011.07575
Autor:
Bredies, Kristian, Valkonen, Tuomo
Publikováno v:
Proceedings of the 9th International Conference on Sampling Theory and Applications (SampTA) 2011, Singapore (2011)
Total Generalized Variation (TGV) has recently been introduced as penalty functional for modelling images with edges as well as smooth variations. It can be interpreted as a "sparse" penalization of optimal balancing from the first up to the $k$-th d
Externí odkaz:
http://arxiv.org/abs/2005.09725
Publikováno v:
SIAM Journal on Imaging Sciences 13(3), 2020
As second-order methods, Gauss--Newton-type methods can be more effective than first-order methods for the solution of nonsmooth optimization problems with expensive-to-evaluate smooth components. Such methods, however, often do not converge. Motivat
Externí odkaz:
http://arxiv.org/abs/2002.08044