Institutt for matematiske fag: Recent submissions
Now showing items 1-20 of 1323
-
Spatial Gaussian Mixture Models Applied to Bayesian Seismic Inversion
(Doctoral theses at NTNU;2020:181, Doctoral thesis, 2020)Summary Stochastic reservoir characterization of a subsurface is the process of creating a quantitative model of the subsurface based on various geophysical measurements to predict the occurrence of hydrocarbons such as ... -
Evaluating thermal losses and storage capacity in high-temperature aquifer thermal energy storage (HT-ATES) systems with well operating limits: insights from a study-case in the Greater Geneva Basin, Switzerland
(Peer reviewed; Journal article, 2020)High-temperature aquifer thermal energy storage (HT-ATES) may play a key role in the development of sustainable energies and thereby in the overall reduction of CO2 emission. To this end, a thorough understanding of the ... -
Invariant-preserving integrators for differential equations
(Doctoral theses at NTNU;2020:166, Doctoral thesis, 2020) -
A revised implicit equal-weights particle filter
(Peer reviewed; Journal article, 2019)Particle filters are fully nonlinear data assimilation methods and as such are highly relevant. While the standard particle filter degenerates for high‐dimensional systems, recent developments have opened the way for new ... -
Discrete fourier analysis on lattice grids
(Journal article; Peer reviewed, 2019)Using group theory we describe the relation between lattice sampling grids and the corresponding non-aliasing Fourier basis sets, valid for all 1-periodic lattices. This technique enable us to extend the results established ... -
On the structure and cohomology ring of connected Hopf algebras
(Peer reviewed; Journal article, 2019)Let p be a prime, and k be a field of characteristic p. We investigate the algebra structure and the structure of the cohomology ring for the connected Hopf algebras of dimension p3, which appear in the classification ... -
A novel approach to rigid spheroid models in viscous flows using operator splitting methods
(Peer reviewed; Journal article, 2019)Calculating cost-effective solutions to particle dynamics in viscous flows is an important problem in many areas of industry and nature. We implement a second-order symmetric splitting method on the governing equations for ... -
Accounting for interspecific competition and age structure in demographic analyses of density dependence improves predictions of fluctuations in population size
(Peer reviewed; Journal article, 2019)Understanding species coexistence has long been a major goal of ecology. Coexistence theory for two competing species posits that intraspecific density dependence should be stronger than interspecific density dependence. ... -
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 ... -
Statistical modeling for safer drilling operations
(Doctoral theses at NTNU;2020:172, Doctoral thesis, 2020) -
A continuous interpolation between conservative and dissipative solutions
(Peer reviewed; Journal article, 2015)We introduce a novel solution concept, denoted -dissipative solutions, that provides a continuous interpolation between conservative and dissipative solutions of the Cauchy problem for the two-component Camassa–Holm system ... -
Efficient Forecasting of Drift Trajectories using Simplified Ocean Models and Nonlinear Data Assimilation on GPUs
(Doctoral theses at NTNU;2020:154, Doctoral thesis, 2020)This thesis presents research on efficient, massively parallel methods and algorithms related to short-term forecasting of drift trajectories in the ocean. The topic has clear societal applications and is an important ... -
Value of Information Analysis for Complex Simulator Models: Application to Wind Farm Maintenance
(Peer reviewed; Journal article, 2020)Many domains require the use of sophisticated simulators to adequately model the effect of chosen alternatives on the decision maker’s value. Decision support in such complex systems brings unique challenges around efficiency, ... -
Three classes of quadratic vector fields for which the Kahan discretization is the root of a generalised Manin transformation
(Peer reviewed; Journal article, 2019)Three classes of quadratic vector fields for which the Kahan discretization is the root of a generalised Manin transformation -
Geometric and integrability properties of Kahan?s method: The preservation of certain quadratic integrals
(Peer reviewed; Journal article, 2019)Given a quadratic vector field on possessing a quadratic first integral depending on two of the independent variables, we give a constructive proof that Kahan's discretization method exactly preserves a nearby modified ... -
Competition models for plant stems
(Peer reviewed; Journal article, 2020)The models introduced in this paper describe a uniform distribution of plant stems competing for sunlight. The shape of each stem, and the density of leaves, are designed in order to maximize the captured sunlight, subject ... -
Topological freeness for C*-correspondences
(Journal article; Peer reviewed, 2019)We study conditions that ensure uniqueness theorems of Cuntz–Krieger type for relative Cuntz–Pimsner algebras associated to a ⁎-correspondence X over a ⁎-algebra A. We give general sufficient conditions phrased in terms ... -
Sampling of entire functions of several complex variables on a lattice and multivariate Gabor frames
(Peer reviewed; Journal article, 2019)We give a general construction of entire functions in d complex variables that vanish on a lattice of the form = A(Z + iZ)d for an invertible complex-valued matrix. As an application, we exhibit a class of lattices of ... -
Dynamic Coarsening and Local Reordered Nonlinear Solvers for Simulating Transport in Porous Media
(Journal article, Peer reviewed, 2020)We present a robust and flexible sequential solution approach in which the flow equation is solved on the original grid, whereas the transport equations are solved with a new dynamic coarsening method that adapts the grid ... -
Testing the effect of quantitative genetic inheritance in structured models on projections of population dynamics
(Peer reviewed; Journal article, 2019)Global climate change is altering the timing of life history events for species living in seasonal environments. These shifts in phenology can lead to the disruption of interspecific relationships with implications for ...