## Search

Now showing items 1-100 of 2505

(Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)

(Doctoral thesis / Doktoravhandling, 2021)

Submarine mass movements are important sources for tsunamis with potential destructive consequences at coastlines. A famous example from historical records is, for instance, the 1929 Grand Banks tsunami in Canada. This ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Background
Gestational age is a useful proxy for assessing developmental maturity, but correct estimation of gestational age is difficult using clinical measures. DNA methylation at birth has proven to be ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Many of the widely used models for description of nonlinear surface gravity waves, in deep or shallow water, such as High Order Spectral Method (HOSM) and Boussinesq-type equations, rely on the elimination of the vertical ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

This study presents wave measurements in the Marginal Ice Zone (MIZ) obtained from ship mounted sensors. The system combines altimeter readings from the ship bow with ship motion correction data to provide estimated single ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Cardiac muscle cells can exhibit complex patterns including irregular behaviour such as chaos or (chaotic) early afterdepolarisations (EADs), which can lead to sudden cardiac death. Suitable mathematical models and their ...

(Chapter / Bokkapittel / AcceptedVersion; Peer reviewed, 2021)

This paper presents the results of statistical analyses on the difference between measured and calculated fatigue rates for an ocean-going container vessel. Data from a hull monitoring system installed on-board this ship ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

Deep Reinforcement Learning (DRL) has recently spread into a range of domains within physics and engineering, with multiple remarkable achievements. Still, much remains to be explored before the capabilities of these methods ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Background
Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and “bulk” flow; and three (respective) potential motive forces have been ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

A sharp version of a recent inequality of Kovalev and Yang on the ratio of the (H1)∗ and H4 norms for certain polynomials is obtained. The inequality is applied to establish a sharp and tractable sufficient condition for ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

With the introduction of the exchange-traded German wind power futures, opportunities for German wind power producers to hedge their volumetric risk are present. We propose two continuous-time multivariate models for wind ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Coupled partial differential equations (PDEs) defined on domains with different dimensionality are usually called mixed-dimensional PDEs. We address mixed-dimensional PDEs on three-dimensional (3D) and one-dimensional (1D) ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Graph products of groups were introduced by Green in her thesis [32]. They have an operator algebraic counterpart introduced and explored in [14]. In this paper we prove Khintchine type inequalities for general C⁎-algebraic ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

The present study was originally motivated by some intriguing exact solutions for waves propagating in nonuniform media. In particular, for special depth profiles reflected waves did not appear and ray theory became exact. ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Two-phase oil and gas flow were simulated in an entirely eccentric annulus and compared with experimental data at horizontal, 4, 10, and 90° inclination. The gas-phase was sulphur hexafluoride and the liquid phase a mixture ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Plants and insects use slender conical structures to transport and collect small droplets, which are propelled along the conical structures due to capillary action. These droplets can deposit a fluid film during their ...

(Doctoral thesis / Doktoravhandling, 2021)

Many important results in mathematics deal with the question of figuring out what objects are ‘the same’. One way of rigorously dealing with this is through the notion of isomorphic objects. However, it is sometimes better ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

We study the dynamic wetting of a self-propelled viscous droplet using the time-dependent lubrication equation on a conical-shaped substrate for different cone radii, cone angles and slip lengths. The droplet velocity is ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

System logs or log files containing textual messages with associated time stamps are generated by many technologies and systems. The clustering technique proposed in this paper provides a tool to discover and identify ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

We study the stability of a unique weak solution to certain parabolic systems with nonstandard growth condition, which are additionally dependent on a cross-diffusion term. More precisely, we show that two unique weak ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Operating in energy and commodity markets require a management of risk using derivative products such as forward and futures, as well as options on these. Many of the popular stochastic models for spot dynamics and weather ...

(Doctoral thesis / Doktoravhandling, 2021)

The development of research and exploration in Arctic waters is very common nowadays. One of the environmental difficulties to carry out research in these regions is the icing of surfaces. After short periods of time, ice ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Structural reliability analysis is concerned with estimation of the probability of a critical event taking place, described by P(g(X)≤0) for some n-dimensional random variable X and some real-valued function g. In many ...

(Doctoral thesis / Doktoravhandling, 2021)

Both in science and industry, the sizes of data sets are growing. It is not uncommon to encounter sets containing millions or even billions of measurements. Without appropriate tools for turning such enormous amounts of ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

Rational quartic spectrahedra in 3-space are semialgebraic convex subsets in R3 of semidefinite, real symmetric (4×4)-matrices, whose boundary admits a rational parameterization. The Zariski closure in CP3 of the boundary ...

(Doctoral thesis / Doktoravhandling, 2021)

In this thesis, two-phase flow in an annular pipe geometry is studied using an open-source software known as OpenFOAM. The data collected through the simulations in this thesis are compared to experimental data collected ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

This work introduces the deconvolution as a technique to reconstruct missing information in data. While the method was originally developed for ocean waves, it will be useful in a wider range of applications where gaps in ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

A novel Dynamic Kernel PCA (DKPCA) method is developed for process monitoring in nonlinear dynamical systems. Classical DKPCA approaches still exhibit vague linearity assumptions to determine the number of principal ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

Experimental and numerical evidence have shown that nonuniform bathymetry may alter significantly the statistical properties of surface elevation in irregular wave fields. The probability of “rogue” waves is increased near ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

We introduce a mean counting function for Dirichlet series, which plays the same role in the function theory of Hardy spaces of Dirichlet series as the Nevanlinna counting function does in the classical theory. The existence ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)

This paper considers data-based real-time adaptive Fault Detection (FD) in Grid-connected PV (GPV) systems under Power Point Tracking (PPT) modes during large variations. Faults under PPT modes remain undetected for longer ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

We introduce a rough perturbation of the Navier–Stokes system and justify its physical relevance from balance of momentum and conservation of circulation in the inviscid limit. We present a framework for a well-posedness ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Background
Several central nervous system diseases are associated with disturbed cerebrospinal fluid (CSF) flow patterns and have typically been characterized in vivo by phase-contrast magnetic resonance ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)

Abstract We study C*-algebras generated by left regular representations of right LCM one-relator monoids and Artin–Tits monoids of finite type. We obtain structural results concerning nuclearity, ideal structure and pure ...

(Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)

We analyse forward prices observed at the Fishpool market, and propose a two-factor continuous-time stochastic process for modelling the time dynamics. The data analysis reveals that the two factors can be assumed to be a ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Background
Infusion testing is a common procedure to determine whether shunting will be beneficial in patients with normal pressure hydrocephalus. The method has a well-developed theoretical foundation and ...

Stochastic Modeling with Fractional and non-Fractional Noises: Applications to Finance and Insurance

(Doctoral thesis / Doktoravhandling, 2020)

In my doctoral work, I have developed stochastic models that use different type of noises, to price financial derivatives and insurance products.
Stock prices have a random component in their behavior that characterizes ...

(Doctoral thesis / Doktoravhandling, 2020)

This thesis is a collection of four papers about symmetric and Hermitian determinantal representations of quartic hypersurfaces.
- Paper I classifies rational quartic symmetroids in 3-space.
- Paper II classifies rational ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Statistical models are often fitted to obtain a concise description of the association of an outcome variable with some covariates. Even if background knowledge is available to guide preselection of covariates, stepwise ...

(Doctoral thesis / Doktoravhandling, 2020)

(Doctoral thesis / Doktoravhandling, 2020)

This thesis presents new statistical methodology, models, and estimators that are geared towards answering scientific questions in epidemiology and medicine, and in economics and finance. The questions are: (i) What is the ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

A user defined cohesive material model is implemented in the LS-DYNA finite element code. The model is based on interface properties characterised from DCB specimens loaded with unequal bending moments. Different mode ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Background
Graph-based reference genomes have become popular as they allow read mapping and follow-up analyses in settings where the exact haplotypes underlying a high-throughput sequencing experiment are ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The recently proposed glymphatic system suggests that bulk flow is important for clearing waste from the brain, and as such may underlie the development of e.g. Alzheimer’s disease. The glymphatic hypothesis is still ...

(Doctoral thesis / Doktoravhandling, 2020)

(Doctoral thesis / Doktoravhandling, 2020)

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

In this paper we aim at modeling stochastic transition rates of state processes in life insurance by using generalized Cox processes. A feature of a our non-Gaussian model is that it can be used to capture ‘regime switching’ ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Using recent results of Bayer–Macrì, we compute in many cases the pseudoeffective and nef cones of the projectivised cotangent bundle of a smooth projective K3 surface. We then use these results to construct explicit ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Background
The standard lasso penalty and its extensions are commonly used to develop a regularized regression model while selecting candidate predictor variables on a time-to-event outcome in high-dimensional ...

(Doctoral thesis / Doktoravhandling, 2020)

Dementia is a growing concern for the health-care in the world and most treatment strategies are not successful. Dementia is associated with accumulation of metabolic waste in the form of protein fragments. Recent breakthroughs ...

(Doctoral thesis / Doktoravhandling, 2020)

It is well known that randomness can be used as an effective tool to turn a priori ill-posed problems into well-posed ones. This is useful both for answering questions at the theoretical as well as the practical levels. ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

We have developed an efficient methodology for Bayesian prediction of lithology and pore fluid, and layer-bounding horizons, in which we include and use spatial geologic prior knowledge such as vertical ordering of ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

In this paper, we provide new results and algorithms (including backtracking versions of Nesterov accelerated gradient and Momentum) which are more applicable to large scale optimisation as in Deep Neural Networks. We also ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We prove a strengthened form of convexity for operator monotone decreasing positive functions defined on the positive real numbers. This extends Ando and Hiai's work to allow arbitrary positive maps instead of states (or ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

This paper focuses on the active flow control of a computational fluid dynamics simulation over a range of Reynolds numbers using deep reinforcement learning (DRL). More precisely, the proximal policy optimization (PPO) ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The process of a circular free falling jet entering an idle pool was studied with the objective of determining a relation between the naturally occurring disturbances on the jet surface and air entrainment. To this end the ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Epigenetic observations are represented by the total number of reads from a given pool of cells and the number of methylated reads, making it reasonable to model this data by a binomial distribution. There are numerous ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

We study first-order concatenation theory with bounded quantifiers. We give axiomatizations with interesting properties, and we prove some normal-form results. Finally, we prove a number of decidability and undecidability results.

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The existence of large and extreme claims of a non-life insurance portfolio influences the ability of (re)insurers to estimate the reserve. The excess over-threshold method provides a way to capture and model the typical ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Present first-order based design code formulations for slender columns in frames with sway, employ sway magnification factors (for global second-order effects) also as moment magnifiers for the individual columns of the ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Let X be a Riemannian manifold and xn a sequence of points in X. Assume that we know a priori some properties of the set A of cluster points of xn. The question is under what conditions that xn will converge. An answer to ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We define Chern–Schwartz–MacPherson (CSM) cycles of an arbitrary matroid. These are balanced weighted fans supported on the skeleta of the corresponding Bergman fan. In the case that the matroid arises from a complex ...

(Doctoral thesis / Doktoravhandling, 2020)

This thesis describes a finite element method for simulation of free-surface flows, such as ocean waves, using the discontinuous Galerkin method. Free-surface flows where there is a large difference in density between two ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We classify rational, irreducible quartic symmetroids in projective 3-space. They are either singular along a line or a smooth conic section, or they have a triple point or a tacnode.

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We prove that there exists a pencil of Enriques surfaces defined over Q with non-algebraic integral Hodge classes of non-torsion type. This gives the first example of a threefold with the trivial Chow group of zero-cycles ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

This paper is concerned with properties of permutation matrices and alternating sign matrices (ASMs). An ASM is a square (0,±1)-matrix such that, ignoring 0’s, the 1’s and −1’s in each row and column alternate, beginning ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We continue our study of the Fourier–Stieltjes algebra associated to a twisted (unital, discrete) C*-dynamical system and discuss how the various notions of equivalence of such systems are reflected at the algebra level. ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We study the derived category of a complete intersection X of bilinear divisors in the orbifold Sym2P(V) . Our results are in the spirit of Kuznetsov’s theory of homological projective duality, and we describe a homological ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

The recent article ‘Satellite conjunction analysis and the false confidence theorem’ (Balch et al. 2019, Satellite conjunction analysis and the false confidence theorem. Proc. R. Soc. A475, 20180565) points to certain ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We show that every automorphism of the Hilbert scheme of n points on a weak Fano or general type surface is natural, i.e., induced by an automorphism of the surface, unless the surface is a product of curves and n=2. In ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Abstract
Purpose
To investigate the comparative effectiveness of dopamine agonists and monoamine oxidase type-B (MAO-B) inhibitors available for treatment of Parkinson’s disease.
...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Waves can drastically transform a sea ice cover by inducing break-up over vast distances in the course of a few hours. However, relatively few detailed studies have described this phenomenon in a quantitative manner, and ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The time it takes a student to graduate with a university degree is mitigated by a variety of factors such as their background, the academic performance at university, and their integration into the social communities of ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

In this paper, we consider option pricing in a framework of the fractional Heston-type model with [Formula: see text]. As it is impossible to obtain an explicit formula for the expectation [Formula: see text] in this case, ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Have great wars become less violent over time, and is there something we might identify as the long peace? We investigate statistical versions of such questions, by examining the number of battle-deaths in the Correlates ...

(Doctoral thesis / Doktoravhandling, 2020)

(Doctoral thesis / Doktoravhandling, 2020)

Biological membranes have fundamental implications in a large number of processes in the cell. As such, membranes possess important properties: they can change their shape as an elastic surface, and they are fluid, which ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

A central point of disagreement, in certain long-standing discussions about a particular whaling dataset in the Scientific Committee of the International Whaling Commission, has directly involved model selection issues for ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

The seller's risk-indifference price evaluation is studied. We propose a dynamic risk-indifference pricing criterion derived from fully-dynamic risk measures on the $L_p$-spaces for $p\in [1,\infty]$. The concept of ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Co-current two-phase simulations of gas-liquid flow with mixture velocities from 1.2 to 4.2 m/s were run in a partially eccentric annulus and compared with entirely eccentric and concentric experimental data collected at ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

Given a set A in the unit interval and the associated Lebesgue measure λ, it is a natural question whether we may (in some sense) compute the measure λ(A) in terms of the set A. Under the moniker measure theoretic uniformity, ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

Somatic copy number alterations are a frequent sign of genome instability in cancer. A precise characterization of the genome architecture would reveal underlying instability mechanisms and provide an instrument for outcome ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

In this paper, we investigate the dynamics of a neuron–glia cell system and the underlying mechanism for the occurrence of seizures. For our mathematical and numerical investigation of the cell model we will use bifurcation ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We introduce two essentially undecidable first-order theories WT and T. The intended model for the theories is a term model. We prove that WT is mutually interpretable with Robinson’s R. Moreover, we prove that Robinson’s ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

The liberalization of energy markets worldwide during recent decades has introduced severe implications for the price formation in these markets. Especially within the European day-ahead electricity markets, increased ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

In this paper, we study a so-called Condition C1 on square matrices with complex coefficients and a weaker Condition C2. For Druzkowski maps Condition C2 is equivalent to the Jacobian conjecture. We show that these conditions ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The goal of this paper is to study a stochastic game connected to a system of forward-backward stochastic differential equations (FBSDEs) involving delay and noisy memory. We derive sufficient and necessary maximum principles ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

Abstract
The study of the topology of real algebraic varieties dates back to the work of Harnack, Klein, and Hilbert in the 19th century; in particular, the isotopy-type classification of real algebraic curves ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

The coupled Darcy–Stokes problem is widely used for modeling fluid transport in physical systems consisting of a porous part and a free part. In this work we consider preconditioners for monolithic solution algorithms of ...

(Doctoral thesis / Doktoravhandling, 2020)

In the last decades the analytical value of data has really become apparent and the amount of data collected has vastly increased. This enables us to approach problems in more data driven manners. In the thesis, I have ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

We report laboratory experiments of long-crested irregular water surface waves propagating over a shoal. For a sufficiently shallow shoal we find that the surface elevation can have a local maximum of skewness and kurtosis ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

When using the Focused Information Criterion (FIC) for assessing and ranking candidate models with respect to how well they do for a given estimation task, it is customary to produce a so-called FIC plot. This plot has the ...

(Doctoral thesis / Doktoravhandling, 2020)

Airflow above water waves represents a challenging problem, relevant both in air-sea interactions and for multiphase pipe flows. Understanding this interaction is important to accurately predict the exchange of heat, ...

(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)

We study the action of the group PGL(4) on the parameter space P 19 of complex cubic surfaces. Specifically, we look at how the techniques used by Aluffi and Faber in [1] can be extended to compute the degree of the orbit ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

Seismic exploration in complex geologic settings and shallow geologic targets has led to a demand for higher spatial and temporal resolution in the final migrated image. Conventional marine seismic and wide-azimuth data ...

(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)

Principal component analysis (PCA) is a common tool in the literature and widely used for process monitoring and fault detection. Traditional PCA is associated with the two well-known control charts, the Hotelling’s T2 and ...