Blar i Department of Mathematics på tittel

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    • Phase field modeling of precipitation and dissolution processes in porous media: Upscaling and numerical experiments 

      Bringedal, Carina; Wolff, Lars V.O.N.; Pop, Iuliu Sorin (Journal article; Peer reviewed, 2020)
      We consider a model for precipitation and dissolution in a porous medium, where ions transported by a fluid through the pores can precipitate at the pore walls and form mineral. Also, the mineral can dissolve and become ...

    • Physical activity level at work and risk of chronic low back pain: A follow-up in the Nord-Trøndelag Health Study 

      Heuch, Ingrid; Heuch, Ivar; Hagen, Knut; Zwart, John-Anker (Peer reviewed; Journal article, 2017-04-10)
      Background: Physical activity in leisure time seems to reduce the risk of low back pain, but it is not known whether occupational activity, as recorded in a representative working population, produces a higher or lower ...

    • Polarizations of powers of graded maximal ideals 

      Almousa, Ayah; Fløystad, Gunnar; Lohne, Henning (Journal article; Peer reviewed, 2022)
      We give a complete combinatorial characterization of all possible polarizations of powers of the graded maximal ideal (x1, x2, . . . , xm) n of a polynomial ring in m variables. We also give a combinatorial description of ...

    • Polish Translation and Validation of the Tinnitus Handicap Inventory and the Tinnitus Functional Index 

      Wrzosek, Małgorzata; Eugeniusz, Szymiec; Wiesława, Klemens; Kotyło, Piotr; Schlee, Winfried; Modrzynska, Małgorzata; Agnieszka, Lang-Małecka; Anna, Preis; Bulla, Jan (Peer reviewed; Journal article, 2016-11-29)
      Objective: The need for validated measures enabling clinicians to classify tinnitus patients according to the severity of tinnitus and screen the progress of therapies in our country led us to translate into Polish and to ...

    • Polynomials homologically supported on determinantal loci 

      Pragacz, P.; Ratajski, J. (Department of Pure Mathematics report no. 61, Research report, 1991-10)

    • A pore network model for calculation of interfacial velocities 

      Nordhaug, Hans Fredrik; Celia, Michael A.; Dahle, Helge K. (Peer reviewed; Journal article, 2003)
      Two-phase flow in porous media is characterized by fluid-fluid interfaces that separate the fluid phases at the pore scale. These interfaces support pressure differences between phases, and their dynamics allow for saturation ...

    • A pore-scale model for permeable biofilm: Numerical simulations and laboratory experiments 

      Landa-Marban, David; Liu, Na; Pop, Iuliu Sorin; Kumar, Kundan; Pettersson, Per; Bødtker, Gunhild; Skauge, Tormod; Radu, Florin Adrian (Peer reviewed; Journal article, 2019)
      In this paper, we derive a pore-scale model for permeable biofilm formation in a two-dimensional pore. The pore is divided into two phases: water and biofilm. The biofilm is assumed to consist of four components: water, ...

    • PorePy: an open-source software for simulation of multiphysics processes in fractured porous media 

      Keilegavlen, Eirik; Berge, Runar Lie; Fumagalli, Alessio; Starnoni, Michele; Stefansson, Ivar; Varela, Jhabriel; Berre, Inga (Journal article; Peer reviewed, 2021)
      Development of models and dedicated numerical methods for dynamics in fractured rocks is an active research field, with research moving towards increasingly advanced process couplings and complex fracture networks. The ...

    • PoroTwin: A Digital Twin for a FluidFlower Rig 

      Keilegavlen, Eirik; Fonn, Eivind; Johannessen, Kjetil Andre; Eikehaug, Kristoffer; Both, Jakub Wiktor; Fernø, Martin; Kvamsdal, Trond; Rasheed, Adil; Nordbotten, Jan Martin (Journal article; Peer reviewed, 2023)
      We present a framework for integrated experiments and simulations of tracer transport in heterogeneous porous media using digital twin technology. The physical asset in our setup is a meter-scale FluidFlower rig. The digital ...

    • Portfolio allocation under asymmetric dependence in asset returns using local Gaussian correlations 

      Sleire, Anders Daasvand; Støve, Bård; Otneim, Håkon; Berentsen, Geir Drage; Tjøstheim, Dag Bjarne; Haugen, Sverre Hauso (Journal article; Peer reviewed, 2021)
      It is well known that there are asymmetric dependence structures between financial returns. This paper describes a portfolio selection method rooted in the classical mean–variance framework that incorporates such asymmetric ...

    • Portfolio Optimization in a Lévy Market with Intertemporal Substitution and Transaction Costs 

      Benth, Fred Espen; Karlsen, Kenneth Hvistendahl; Reikvam, Kristin (Department of Applied Mathematics report, Research report, 2000-05)

    • Portfolio Optimization with PCC-GARCH-CVaR model 

      Xi, Linda Mon (Master thesis, 2014-06-02)
      This thesis investigates the Conditional Value-at-Risk (CVaR) portfolio optimization approach combined with a univariate GARCH model and pair-copula constructions (PCC) to determine the optimal asset allocation for a ...

    • Post-lie algebras and isospectral flows 

      Ebrahimi-Fard, Kurusch; Lundervold, Alexander; Mencattini, Igor; Munthe-Kaas, Hans (Peer reviewed; Journal article, 2015-11-20)
      In this paper we explore the Lie enveloping algebra of a post-Lie algebra derived from a classical R-matrix. An explicit exponential solution of the corresponding Lie bracket flow is presented. It is based on the solution ...

    • A posteriori error estimates for hierarchical mixed-dimensional elliptic equations 

      Varela, Jhabriel; Ahmed, Elyes; Keilegavlen, Eirik; Nordbotten, Jan Martin; Radu, Adrian Florin (Journal article; Peer reviewed, 2022)
      Mixed-dimensional elliptic equations exhibiting a hierarchical structure are commonly used to model problems with high aspect ratio inclusions, such as flow in fractured porous media. We derive general abstract estimates ...

    • A posteriori error estimation and adaptivity for multiple-network poroelasticity 

      Ødegaard, Emilie Eliseussen; Rognes, Marie Elisabeth; Thompson, Travis B. (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 ...

    • A posteriori error estimation and modeling of unsaturated flow in fractured porous media 

      Varela Estigarribia, Jhabriel Daniel (Doctoral thesis, 2022-06-17)
      This doctoral thesis focuses on three topics: (1) modeling of unsaturated flow in fractured porous media, (2) a posteriori error estimation for mixed-dimensional elliptic equations, and (3) contributions to open-source ...

    • Postinjection Normal Closure of Fractures as a Mechanism for Induced Seismicity 

      Ucar, Eren; Berre, Inga; Keilegavlen, Eirik (Peer reviewed; Journal article, 2017-10-04)
      Understanding the controlling mechanisms underlying injection-induced seismicity is important for optimizing reservoir productivity and addressing seismicity-related concerns related to hydraulic stimulation in Enhanced ...

    • Potensialet for dyp geotermisk energi i Norge: Modellering av varmeutvinning fra konstruerte geotermiske system 

      Brun, Knut-Erland (Master thesis, 2010-10-05)
      Dette prosjektet tar for seg to ulike modeller for et konstruert geotermisk system; et lukket enkeltbrønn-system og et åpent, sprekkdominert system. Enkeltbrønn-systemet er modellert eksplisitt, og modellen er også tilpasset ...

    • Practical approaches to study microbially induced calcite precipitation at the field scale 

      Marban, David Landa; Tveit, Svenn; Kumar, Kundan; Gasda, Sarah (Journal article; Peer reviewed, 2021)
      Microbially induced calcite precipitation (MICP) is a new and sustainable technology which utilizes biochemical processes to create barriers by calcium carbonate cementation; therefore, this technology has a potential to ...

    • Pre- and post-lie algebras: The algebro-geometric view 

      Fløystad, Gunnar; Munthe-Kaas, Hans (Peer reviewed; Journal article, 2019)
      We relate composition and substitution in pre- and post-Lie algebras to algebraic geometry. The Connes-Kreimer Hopf algebras and MKW Hopf algebras are then coordinate rings of the infinite-dimensional affine varieties ...