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  • An Energy Balance Model on an Infinite Line 

    Elvevold, Ask (Master thesis; Mastergradsoppgave, 2022-06-01)
    The thesis is an expansion of the work Gerald R. North did in 1975 on an energy balance climate model. By considering a similar model on an infinite line, and allowing the heat diffusion coefficient to vary on the line, more complicated behaviour arose from the model. Much of Norths work was recreated on the infinite lines, but a lot of new discoveries were made. Among what was found were spontaneous ...
  • Effects of feedbacks for an energy balance model on a circle 

    Brynjulfsen, Synne (Mastergradsoppgave; Master thesis, 2022-05-31)
    A simple, North like, energy balance model on a circle is studied using boundary formulations derived with Green's functions for the stationary case, and a pseudo-spectral and finite difference solution for the time dependent case. The bifurcation software Auto-07p is also applied. The boundary formulation solution can be solved analytically in most cases, and is solved for bifurcation diagrams. ...
  • Killing Tensors in Koutras-McIntosh Spacetimes 

    Steneker, Wijnand (Mastergradsoppgave; Master thesis, 2022-05-15)
    This thesis is concerned with the (non)existence of Killing Tensors in Koutras-McIntosh spacetimes. Killing tensors are of particular interest in general relativity, because these correspond to conserved quantities for the geodesic motion. For instance, Carter found such a conserved quantity in the Kerr metric which he used to explicitly integrate the geodesic equations. The equation defining ...
  • Wachpress Conjecture Restricted To Arrangements Of Three Conics 

    Schena, Alessandro (Mastergradsoppgave; Master thesis, 2022-05-15)
    This thesis discusses Wachpress conjecture restricted to arrangements of three conics. Wachpress conjectured the existence of a set of barycentric coordinates, namely Wachpress coordinates, on all polycons. Barycentric coordinates are very useful in many different fields as they can be used to define a finite element approximation scheme with linear precision. This thesis focuses on the conjecture ...
  • On the effects of symmetry in the energy balance on a sphere 

    Samuelsberg, Aksel (Mastergradsoppgave; Master thesis, 2022-05-15)
    Simple climate models have gathered much attention as they have suggested the possibility of abrupt climate change associated with tipping points. Several simple climate models are found to have multiple equilibria, but in most cases similar equilibria do not appear or become too difficult to find in complex, fully coupled earth system models. In this thesis, we investigate a simple climate model, ...
  • Individual-Based Modeling of COVID-19 Vaccine Strategies 

    Skagseth, Håvard Mikal (Master thesis; Mastergradsoppgave, 2021-06-01)
    COVID-19 is a respiratory disease with influenza-like symptoms originating from Wuhan, China, towards the end of 2019. There has been developed multiple vaccines to contain the virus and to protect the most vulnerable people in society. In this thesis we look at two different vaccination strategies to prevent most deaths and years of life lost. We conclude that the safest and most consistent strategy ...
  • Real Plane Algebraic Curves 

    González García, Pedro (Master thesis; Mastergradsoppgave, 2021-06-18)
    This master thesis studies several properties of real plane algebraic curves, focusing on the case of even degree. The question of the relative positions of the connected components of real plane algebraic curves originates in Hilbert's sixteenth problem which, despite its prominence, is still open in the case of higher degree curves. The goal of this thesis is an exposition of fundamental ...
  • Symmetric Ideals 

    Lien, Arne (Mastergradsoppgave; Master thesis, 2021-05-14)
    Polynomials appear in many different fields such as statistics, physics and optimization. However, when the degrees or the number of variables are high, it generally becomes quite difficult to solve polynomials or to optimize polynomial functions. An approach that can often be helpful to reduce the complexity of such problems is to study symmetries in the problems. A relatively new field, that has ...
  • Ice-albedo tipping points in a diffusive energy-balance model with land and ocean 

    Hilbertsen, Kristian Bergum (Mastergradsoppgave; Master thesis, 2021-01-20)
    The ice-albedo feedback is associated with the nonlinearity in the climate system, due to the sudden change in albedo between ice-free and ice-covered surfaces. This nonlinearity can potentially cause abrupt and dramatic shifts in the climate, referred to as tipping points. It is also believed that this mechanism has contributed significantly to the precipitous losses of Arctic sea ice, which have ...
  • A boundary integral approach to the modeling of surface waves in a wave tank 

    Thygesen, Sander Bøe (Master thesis; Mastergradsoppgave, 2020-06-14)
    Boundary integral equations (BIEs) are used to model surface waves in a wave tank. Assuming an ideal fluid, the velocity of the fluid can be considered as a potential flow and be modeled by the Laplace equation on the domain. The domain in this case will be a section of a wave channel with an incoming wave from the right, a rigid bottom, a reflective wall on the right and a time varying surface that ...
  • A bidirectional pulse propagation model for extreme nonlinear optics: derivation and implementation. 

    Korzeniowska, Magdalena (Master thesis; Mastergradsoppgave, 2020-05-13)
    With growing capabilities of high-intensity laser beams to generate ultra-short pulses of light, the simulation of pulse propagation in nonlinear media is expected to catch up with the front-line experimental setups. Among the challenges of nonlinear material response modeling is the ability to capture the back-scatter effect - a phenomenon inherently elusive for the well-established methods of ...
  • Joint Invariants of Symplectic and Contact Lie Algebra Actions 

    Andreassen, Fredrik (Master thesis; Mastergradsoppgave, 2020-06-23)
    By restricting generating functions of infinitesimal symmetries of symplectic and contact vector spaces to quadratic forms, we obtain a finite-dimensional Lie subalgebra, consisting of vector fields isomorphic to the linear symplectic or conformal symplectic algebra. This allows us to look for joint invariants of the diagonal action of g on product manifolds. We find an explicit recipe for creating ...
  • Differential Invariants of Symplectic and Contact Lie Algebra Actions 

    Jensen, Jørn Olav (Master thesis; Mastergradsoppgave, 2020-06-23)
    In this thesis we consider the equivalence problem for symplectic and conformal symplectic group actions on submanifolds and functions. We solve the equivalence problem for general submanifolds by means of computing differential invariants and describing all the invariants of the associated group action by appealing to the Lie-Tresse theorem.
  • The Four Faces of Hyperelliptic curves 

    Boyne, Marcus L. (Master thesis; Mastergradsoppgave, 2020-05-13)
    In this thesis we will look at elliptic and hyperelliptic curves. There are three abelian groups that are isomorphic to hyperelliptic curves. The Jacobian of hyperelliptic curves, the ideal class group and the form class group, will all be defined and given abelian group structure. We will give an algorithm for point addition and point doubling done exclusively in the jacobian of the curve. ...
  • Group Cohomology and Extensions 

    Breivik, Markus Nordvoll (Master thesis; Mastergradsoppgave, 2019-08-31)
    The goal of this thesis is to classify all extensions where the kernel has order p^s and the cokernel has order p^t, p is a prime, and 1 ≤ s,t ≤ 2. We determine (up to weak congruence) the different combinations of kernel, cokernel and operators, and for each case, calculate the second cohomology group. By comparing resolutions, we get an explicit correspondence between the second cohomology group ...
  • Mathematics of Viral Infections: A Review of Modeling Approaches and A Case-Study for Dengue Dynamics 

    Yong, Chung Han (Master thesis; Mastergradsoppgave, 2018-09-20)
    In this thesis we use mathematical models to study the mechanisms by which diseases spread. Transmission dynamics is modelled by the class of SIR models, where the abbreviation stands for susceptible (S), infected (I) and recovered (R). These models are also called compartmental models, and they serve as the basic mathematical framework for understanding the complex dynamics of infectious diseases. ...
  • Modelling high intensity laser pulse propagation in air using the modified Korteweg-de Vries equation 

    Rørnes, Bjarne (Master thesis; Mastergradsoppgave, 2018-06-01)
    Ultrafast laser pulse experiments and applications are entering a phase that challenges the validity of mathematical models utilised to model longer pulses in nonlinear optics. This thesis aims to propose a possible mathematical model for high intensity laser pulse propagation in air through a multiple scales expansion of Maxwell’s equations and discuss a method on how to solve the corresponding ...
  • Modern climate-economic models and climate policies 

    Grabovskaia, Sofiia (Master thesis; Mastergradsoppgave, 2018-05-15)
    The problem of climate change is one of the most discussed problems nowadays. The global warming has an unquestionable influence on the economic growth of the different countries, and, consequently, on the whole world economics. The climate economics thus is an actual topic to study. Moreover, it is important to predict how the climate will change over the next century and which resulting outcomes ...
  • Almost affine codes and matroids 

    Diachkov, Konstantin (Master thesis; Mastergradsoppgave, 2017-05-15)
    In this thesis we study various types of block codes, like linear, mutlti-linear, almost affine codes. We also look at how these codes can be described by associated matroids. In addition we look at flags (chains) of codes and see how their behavior can be described using demi-matroids. We also introduce weight polynomials for almost affine codes.
  • On the Ewald-Oseen scattering formulation for linear and nonlinear transient wave scattering 

    Kuzmina, Anastasiia (Master thesis; Mastergradsoppgave, 2017-05-16)
    In this thesis work we develop and apply EOS formulation to three scattering problems: two of them are 1D problems and one is 2D. The first chapter comprises EOS formulations and numerical implementation for 1D scattering problems. Also in this chapter we use different numerical methods to solve test problem and choose the most stable and accurate method for solving of the given 1D problems. ...

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