• The Role of Wettability Alteration in Subsurface CO2 Storage: Modeling and Numerical Analysis 

  Kassa, Abay Molla (Doctoral thesis, 2021-12-06)

  This dissertation is aimed to provide mathematical frameworks to assess the large-scale deployment of CO2 in a subsurface formation, where the formation wettability is assumed to be altering through exposure time to the ...

• Coherence for Monoidal and Symmetric Monoidal Groupoids in Homotopy Type Theory 

  Piceghello, Stefano (Doctoral thesis, 2021-12-03)

  Homotopy Type Theory (HoTT) is a variant of Martin-Löf Type Theory (MLTT) developed in such a way that types can be interpreted as infinity-groupoids, where the iterated construction of identity types represents the different ...

• A study of the influence of vorticity, capillarity and slope angle on the properties of shoaling and breaking waves 

  Bjørnestad, Maria (Doctoral thesis, 2021-10-28)

  Fluid motion and wave patterns have fascinated humans for centuries if not millennia. Water waves have been studied out of curiosity such as observing the ripples created by a stone dropped in a pond as well as practical ...

• Effective permeability of deformation bands in fault damage zones – Can deformation bands reduce the risk of fault leakage? 

  Berge, Runar Lie; Gasda, Sarah Eileen; Keilegavlen, Eirik; Sandve, Tor Harald (SINTEF Proceedings;7, Chapter, 2021)

  Faults are major geological structures that can dominate the flow paths in subsurface reservoirs by, e.g., connecting otherwise unconnected layers. In CO2 storage sites where the faults act as the main structural trap, the ...

• Robust Optimization for Sequential Field Development Planning 

  Wang, Lingya (Doctoral thesis, 2021-09-24)

  To achieve high profitability from an oil field, optimizing the field development strategy (e.g., well type, well placement, drilling schedule) before committing to a decision is critically important. The profitability at ...

• Improving Sequential Decisions – Efficiently Accounting for Future Learning 

  Wang, Lingya; Oliver, Dean (Journal article; Peer reviewed, 2021)

  In sequential field development planning, past decisions not only directly affect the maximum achievable expected NPV but also influence the future information that can be used to reduce geological uncertainty. To act ...

• Brauer Groups of Bielliptic Surfaces and Twisted Derived Equivalences 

  Vodrup, Magnus Røen (Doctoral thesis, 2021-08-30)

  This thesis focuses on two interrelated projects. The first project concerns the study of bielliptic surfaces, their Brauer groups and the pullback maps from their Brauer groups to those of their canonical covers. We prove ...

• Moduli of non-standard Nikulin surfaces in low genus 

  Knutsen, Andreas Leopold; Lelli-Chiesa, Margherita; Verra, Alessandro (Journal article; Peer reviewed, 2020)

  Primitively polarized genus g Nikulin surfaces (S, M, H) are of two types, that we call standard and non-standard depending on whether the lattice embedding Z[H] ⊕⊥ N ⊂ Pic S is primitive. Here H is the genus g polarization ...

• Conditioning reservoir models on vast data sets 

  Soares, Ricardo Vasconcellos (Doctoral thesis, 2021-09-09)

  History matching is a valuable process to obtain better models and a more reliable forecast in oil reservoir applications. In such processes, one conditions the simulation models on the observed data from the field. One ...

• Impact of parents' education on variation in hospital admissions for children: a population-based cohort study 

  Olsen, Frank; Balteskard, Lise; Uleberg, Bård Erling; Jacobsen, Bjarne K.; Heuch, Ivar; Moen, Atle (Journal article; Peer reviewed, 2021)

  Objectives To assess the impact of parental educational level on hospital admissions for children, and to evaluate whether differences in parents' educational level can explain geographic variation in admission rates. ...

• Fast robust optimization using bias correction applied to the mean model 

  Wang, Lingya; Oliver, Dean (Peer reviewed; Journal article, 2021)

  Ensemble methods are remarkably powerful for quantifying geological uncertainty. However, the use of the ensemble of reservoir models for robust optimization (RO) can be computationally demanding. The straightforward ...

• Admissibility conditions for Riemann data in shallow water theory 

  Paulsen, Martin Oen; Kalisch, Henrik (Journal article; Peer reviewed, 2020)

  Consideration is given to the shallow-water equations, a hyperbolic system modeling the propagation of long waves at the surface of an incompressible inviscible fluid of constant depth. It is well known that the solution ...

• Pairwise local Fisher and naive Bayes: Improving two standard discriminants 

  Otneim, Håkon; Jullum, Martin; Tjøstheim, Dag Bjarne (Journal article; Peer reviewed, 2020)

  The Fisher discriminant is probably the best known likelihood discriminant for continuous data. Another benchmark discriminant is the naive Bayes, which is based on marginals only. In this paper we extend both discriminants ...

• Well-Posedness for a Whitham–Boussinesq System with Surface Tension 

  Dinvay, Evgueni (Journal article; Peer reviewed, 2020)

  We regard the Cauchy problem for a particular Whitham–Boussinesq system modelling surface waves of an inviscid incompressible fluid layer. The system can be seen as a weak nonlocal dispersive perturbation of the shallow ...

• Nonlinear Spectral Analysis: A Local Gaussian Approach 

  Jordanger, Lars Arne; Tjøstheim, Dag Bjarne (Journal article; Peer reviewed, 2020)

  The spectral distribution f(ω) of a stationary time series {Yt}t∈Z can be used to investigate whether or not periodic structures are present in {Yt}t∈Z, but f(ω) has some limitations due to its dependence on the autocovariances ...

• Extreme wave runup on a steep coastal profile 

  Bjørnestad, Maria; Kalisch, Henrik (Journal article; Peer reviewed, 2020)

  It is shown that very steep coastal profiles can give rise to unexpectedly large wave events at the coast. We combine insight from exact solutions of a simplified mathematical model with photographs from observations at ...

• Robust nonlinear regression estimation in null recurrent time series 

  Bravo, Francesco; Li, Degui; Tjøstheim, Dag Bjarne (Journal article; Peer reviewed, 2020)

  In this article, we study parametric robust estimation in nonlinear regression models with regressors generated by a class of non-stationary and null recurrent Markov processes. The nonlinear regression functions can be ...

• Stable mixed finite elements for linear elasticity with thin inclusions 

  Boon, Wietse; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2021)

  We consider mechanics of composite materials in which thin inclusions are modeled by lower-dimensional manifolds. By successively applying the dimensional reduction to junctions and intersections within the material, a ...

• Guaranteed and computable error bounds for approximations constructed by an iterative decoupling of the Biot problem 

  Kumar, Kundan; Kyas, Svetlana; Nordbotten, Jan Martin; Repin, Sergey (Journal article; Peer reviewed, 2021)

  The paper is concerned with guaranteed a posteriori error estimates for a class of evolutionary problems related to poroelastic media governed by the quasi-static linear Biot equations. The system is decoupled by employing ...

• On the unique continuation of solutions to non-local non-linear dispersive equations 

  Kenig, C.E.; Pilod, Didier Jacques Francois; Ponce, G.; Vega, L. (Journal article; Peer reviewed, 2020)

  We prove unique continuation properties of solutions to a large class of nonlinear, non-local dispersive equations. The goal is to show that if u1,u2 are two suitable solutions of the equation defined in Rn×[0,T] such that ...

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