Department of Mathematics
Recent Submissions
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Decay estimates of Green's matrices for discrete-time linear periodic systems
(Journal article; Peer reviewed, 2023)We study periodic Lyapunov matrix equations for a general discrete-time linear periodic system Bpxp−Apxp−1=fp, where the matrix coefficients Bp and Ap can be singular. The block coefficients of the inverse operator of the ... -
The FluidFlower Validation Benchmark Study for the Storage of CO2
(Journal article; Peer reviewed, 2023)Successful deployment of geological carbon storage (GCS) requires an extensive use of reservoir simulators for screening, ranking and optimization of storage sites. However, the time scales of GCS are such that no sufficient ... -
The heritability curve and its applications to human non-Mendelian traits
(Doctoral thesis, 2023-12-08)Arvbarhet er et viktig mål for å beskrive en ikke-mendelsk egenskap; den måler i hvilken andel verdien av egenskapen påvirkes av genetisk materiale. I klassiske biometriske modeller er arvbarheten konstant over hele ... -
DarSIA: An Open-Source Python Toolbox for Two-Scale Image Processing of Dynamics in Porous Media
(Journal article; Peer reviewed, 2023)Understanding porous media flow is inherently a multi-scale challenge, where at the core lies the aggregation of pore-level processes to a continuum, or Darcy-scale, description. This challenge is directly mirrored in image ... -
Numerical Treatment of State-Dependent Permeability in Multiphysics Problems
(Journal article; Peer reviewed, 2023)Constitutive laws relating fluid potentials and fluxes in a nonlinear manner are common in several porous media applications, including biological and reactive flows, poromechanics, and fracture deformation. Compared to ... -
Machine learning in marine ecology: an overview of techniques and applications
(Journal article; Peer reviewed, 2023)Machine learning covers a large set of algorithms that can be trained to identify patterns in data. Thanks to the increase in the amount of data and computing power available, it has become pervasive across scientific ... -
Covering tour problem with varying coverage: Application to marine environmental monitoring
(Journal article; Peer reviewed, 2023)In this paper, we present a novel variant of the Covering Tour Problem (CTP), called the Covering Tour Problem with Varying Coverage (CTP-VC). We consider a simple graph 𝐺 = (𝑉 ,𝐸), with a measure of importance assigned ... -
The aromatic bicomplex for the description of divergence-free aromatic forms and volume-preserving integrators
(Journal article; Peer reviewed, 2023)Aromatic B-series were introduced as an extension of standard Butcher-series for the study of volume-preserving integrators. It was proven with their help that the only volume-preserving B-series method is the exact flow ... -
Menopausal hormone therapy, oral contraceptives and risk of chronic low back pain: the HUNT Study
(Journal article; Peer reviewed, 2023)Background There are indications that use of menopausal hormone therapy (MHT) and oral contraceptives (OC) increases the risk of low back pain (LBP), with higher oestrogen levels involved in the underlying mechanisms. The ... -
Lipid Levels During Adult Lifetime in Men and Women With and Without a Subsequent Incident Myocardial Infarction: A Longitudinal Analysis of Data From the Tromsø Study 1974 to 2016
(Journal article; Peer reviewed, 2023)Background The atherosclerotic effect of an adverse lipid profile is assumed to accumulate throughout life, leading to increased risk of myocardial infarction (MI). Still, little is known about age at onset and duration ... -
Simulation of fracture slip and propagation in hydraulic stimulation of geothermal reservoirs
(Doctoral thesis, 2023-09-01)Rollen til hydraulisk stimulering i å øke produksjonen fra geotermiske reservoarer, og muliggjøre kommersiell utnyttelse av et større spekter av geotermiske ressurser, har fått økt oppmerksomhet de siste tiårene. Under ... -
Mitochondrial network structure controls cell-to-cell mtDNA variability generated by cell divisions
(Journal article; Peer reviewed, 2023)Mitochondria are highly dynamic organelles, containing vital populations of mitochondrial DNA (mtDNA) distributed throughout the cell. Mitochondria form diverse physical structures in different cells, from cell-wide ... -
Convergence of Chandrashekar’s Second-Derivative Finite-Volume Approximation
(Journal article; Peer reviewed, 2023)We consider a slightly modified local finite-volume approximation of the Laplacian operator originally proposed by Chandrashekar (Int J Adv Eng Sci Appl Math 8(3):174–193, 2016, https://doi.org/10.1007/s12572-015-0160-z). ... -
On the formation of coastal rogue waves in water of variable depth
(Journal article; Peer reviewed, 2023)Wave transformation is an intrinsic dynamic process in coastal areas. An essential part of this process is the variation of water depth, which plays a dominant role in the propagation features of water waves, including a ... -
A posteriori error estimation and adaptivity for multiple-network poroelasticity
(Journal article; Peer reviewed, 2023)The multiple-network poroelasticity (MPET) equations describe deformation and pressures in an elastic medium permeated by interacting fluid networks. In this paper, we (i) place these equations in the theoretical context ... -
Decay of solitary waves of fractional Korteweg-de Vries type equations
(Journal article; Peer reviewed, 2023)We study the solitary waves of fractional Korteweg-de Vries type equations, that are related to the 1- dimensional semi-linear fractional equations: |D|αu + u − f (u) = 0, with α ∈ (0, 2), a prescribed coefficient p∗(α), ... -
Zero-shot classification of salmon lice images by siamese neural networks
(Master thesis, 2023-06-22)Deep learning models, such as neural networks and its variations, have proven exceptionally useful in the current state of society. However, facilitating competitive performances requires large amounts of data for the ... -
Brain Tumor Segmentation Based on Minimum Spanning Tree
(Journal article; Peer reviewed, 2022-03-11)In this paper, we propose a minimum spanning tree-based method for segmenting brain tumors. The proposed method performs interactive segmentation based on the minimum spanning tree without tuning parameters. The steps ... -
Essays on Portfolio Risk Management and Weather Derivatives
(Doctoral thesis, 2023-08-25)Denne avhandlingen handler om utvikling og praktisk implementering av risikostyringsmetoder for investeringsporteføljer, energiporteføljer, og håndtering av vær- og forurensningsrisiko. Avhandlingen inkluderer tre ... -
Medical Image Segmentation: Thresholding and Minimum Spanning Trees
(Doctoral thesis, 2023-08-18)I bildesegmentering deles et bilde i separate objekter eller regioner. Det er et essensielt skritt i bildebehandling for å definere interesseområder for videre behandling eller analyse. Oppdelingsprosessen reduserer ...
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