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Unique Factorization of Ideals
(Master thesis, 2013)We study Dedekind domains, where ideals factorize uniquely into a product ofprime ideals. This subject is of interest as general elements in these rings donot necessarily factorize uniquely. -
Uniqueness and properties of distributional solutions of nonlocal equations of porous medium type
(Journal article; Peer reviewed, 2017)We study the uniqueness, existence, and properties of bounded distributional solutions of the initial value problem for the anomalous diffusion equation ∂tu−Lμ[φ(u)]=0. Here Lμ can be any nonlocal symmetric degenerate ... -
Uniqueness of conservative solutions for the Hunter–Saxton equation
(Peer reviewed; Journal article, 2022)We show that the Hunter–Saxton equation ut+uux=14(∫x−∞dμ(t,z)−∫∞xdμ(t,z)) and μt+(uμ)x=0 has a unique, global, weak, and conservative solution (u,μ) of the Cauchy problem on the line. -
Universal Zero Dynamics: The SISO Case
(Chapter, 2021)Given a single-input, single-output (SISO) system with a Chen-Fliess series representation whose generating series has a well defined relative degree, it is shown that there is a notion of universal zero dynamics that ... -
Universality and distribution of zeros and poles of some zeta functions
(Peer reviewed; Journal article, 2020)This paper studies zeta functions of the form P∞ n=1 χ(n)n −s , with χ a completely multiplicative function taking only unimodular values. We denote by σ(χ) the infimum of those α such that the Dirichlet series P∞ n=1 χ(n)n ... -
University students’ learning approaches: An adaptation of the revised two-factor study process questionnaire to Norwegian
(Journal article; Peer reviewed, 2019)This paper reports a Norwegian validation study of a widely used instrument to measure students’ approaches to learning, namely, Bigg’s revised two-factor study process questionnaire (R-SPQ-2F). Its cultural sensitivity ... -
Unstable splittings in Hodge filtered Brown-Peterson cohomology
(Journal article, 2018)We construct Hodge filtered function spaces associated to infinite loop spaces. For Brown–Peterson cohomology, we show that the corresponding Hodge filtered spaces satisfy an analog of Wilson’s unstable splitting. As a ... -
Unstructured PEBI-grids Adapting to Geological Features in Subsurface Reservoirs
(Master thesis, 2016)Extensive research has been done on the generation of unstructured grids in reservoir simulation, with the aim of better representing the geology. We introduce UPR (Unstructured PEBI-grids for Reservoirs), a free, open ... -
Unstructured Voronoi grids conforming to lower-dimensional objects
(Journal article; Peer reviewed, 2018)We present a novel mixed-dimensional method for generating unstructured polyhedral grids that conform to prescribed geometric objects in arbitrary dimensions. Two types of conformity are introduced: (i) control-point ... -
Upscaling models of CO2 migration through low-permeable layers in porous media
(Master thesis, 2020)In this thesis we investigate methods preserving the effects of thin layers of rock with low permeability on flow behaviour while upscaling geological models of porous media. More specifically, we study this upscaling in ... -
Upscaling of Water-Flooding Scenarios and Modeling of Polymer Flow
(Doctoral thesis at NTNU;2016:12, Doctoral thesis, 2016)This thesis considers simulations of the fluid flow in petroleum reservoirs, and includes work on upscaling methods and on modeling of polymer flood- ing, which is a particular method of enhanced oil recovery. The details ... -
Use of dynamically adapted basis functions to accelerate multiscale simulation of complex geomodels
(Chapter, 2018)A number of different multiscale methods have been developed as a robust alternative to upscaling and as a means for accelerated reservoir simulation of high-resolution geomodels. In their basic setup, multiscale methods ... -
Using an autonomous underwater vehicle with onboard stochastic advection-diffusion models to map excursion sets of environmental variables
(Peer reviewed; Journal article, 2021)New robotic sensor platforms have computing resources that enable a rich set of tasks for adaptive monitoring of the environment. But to substantially augment the toolbox of environmental sensing, such platforms must be ... -
Using discrete Darboux polynomials to detect and determine preserved measures and integrals of rational maps
(Peer reviewed; Journal article, 2019)In this letter we propose a systematic approach for detecting and calculating integrals and preserved measures of rational maps. The approach is based on the use of cofactors and discrete Darboux polynomials and relies on ... -
Using Ensemble Methods to Improve the Performance of Prediction - Statistical Analysis of a Myocardial Infarction Data Set from the HUNT Study
(Master thesis, 2017)The main focus of this thesis is to evaluate the use of ensemble methods to improve the performance of prediction, when applied on a myocardial infarction (MI) data set from the HUNT study. The data set comes from a ... -
Using GLM to Analyze Acceptability Judgement Test Data
(Master thesis, 2021)I denne oppgaven har vi evaluert lingvistiske forskningsspørsmål ved å bruke GLM modeller og andel korrekt svar av setninger fra Akseptabilitetstestdata gjennomført av elever fra videregående skoler med en, to, fire eller ... -
Using Hidden Markov Models for Musical Chord Prediction
(Master thesis, 2017)Music is made up of a melody and chords that accompany the melody. Finding suitable chords, can be hard and time consuming. This thesis investigates the use of Hidden Markov models (HMMs) to assist in this process. The ... -
Using machine learning to assess the extent of busy ambulances and its impact on ambulance response times: A retrospective observational study
(Peer reviewed; Journal article, 2024)Background Ambulance response times are considered important. Busy ambulances are common, but little is known about their effect on response times. Objective To assess the extent of busy ambulances in Central Norway ... -
Using persistent homology to reveal hidden covariates in systems governed by the kinetic Ising model
(Journal article; Peer reviewed, 2018)We propose a method, based on persistent homology, to uncover topological properties of a priori unknown covariates in a system governed by the kinetic Ising model with time-varying external fields. As its starting point ... -
Using the Composite Likelihood Method on 4D AVA Seismic Data
(Master thesis, 2011)This thesis is concerned with 4D AVA seismic inversion problems. By comparing two seismic surveys done over the same area, but at different times, one hopes to discover untapped pockets of oil or gas. Using the full ...