Sökning: "Hellsten"

Visar resultat 16 - 20 av 26 avhandlingar innehållade ordet Hellsten.

  1. 16. Numerical solution of quasilinear kinetic diffusion equations in toroidal plasmas

    Författare :Lars Josef Höök; Torbjörn Hellsten; Thomas Johnson; Jukka Heikkinen; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : One of the main challenges for the realization of a working fusion power plant is an increased detailed understanding of kinetic phenomena in toroidal plasmas. The tokamak is a toroidal, magnetically confined plasma device and is currently the main line towards a power plant. LÄS MER

  3. 17. Variance reduction methods for numerical solution of plasma kinetic diffusion

    Författare :Lars Josef Höök; Torbjörn Hellsten; Thomas Johnson; Lars-Göran Ericsson; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; variance reduction; Monte Carlo; quasi-Monte Carlo; kinetic diffusion; stochastic differential equation;

    Sammanfattning : Performing detailed simulations of plasma kinetic diffusion is a challenging task and currently requires the largest computational facilities in the world. The reason for this is that, the physics in a confined heated plasma occur on a broad range of temporal and spatial scales. LÄS MER

  4. 18. Fast wave heating and current drive in tokamaks

    Författare :Martin Laxåback; Torbjörn Hellsten; Raymond Koch; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Tokamak; JET; ITER; thermonuclear fusion; fast wave; heating; current drive; ion cyclotron resonance; polychromatic; finite orbit widths; RF-induced transport; neutral beam injection; fusion born alpha particles; magnetosonic eigenmodes; parasitic absorption; modelling; weighted Monte Carlo scheme; Fysik; Physics; Fysik;

    Sammanfattning : This thesis concerns heating and current drive in tokamak plasmas using the fast magnetosonic wave in the ion cyclotron range of frequencies. Fast wave heating is a versatile heating method for thermonuclear fusion plasmas and can provide both ion and electron heating and non-inductive current drive. LÄS MER

  5. 19. Explicit algebraic turbulence modelling in buoyancy-affected shear flows

    Författare :Werner Lazeroms; Arne Johansson; Antti Hellsten; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Turbulent flows affected by buoyancy forces occur in a large amount of applica-tions, from heat transfer in industrial settings to the effects of stratification inEarth’s atmosphere. The two-way coupling between the Reynolds stresses andthe turbulent heat flux present in these flows poses a challenge in the searchfor an appropriate turbulence model. LÄS MER

  7. 20. En reformerad lärare : Konstruktionen av en professionell och betygssättande lärare i skolpolitik och skolpraktik

    Författare :Larissa Mickwitz; Christian Lundahl; Meeri Hellstén; Tore West; Daniel Sundberg; Stockholms universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; teachers; professionalism; grading; school reform; curriculum theory; institutionalism; discourse theory; policy analysis; lärare; professionalism; betyg; läroplansteori; institutionalism; diskursteori; skolreformer; policyanalys; pedagogik; Education;

    Sammanfattning : This doctoral thesis investigates the interrelatedness between school policy and practice. In the thesis, the construction of “the teacher” is analysed in school policy documents and teacher interviews. LÄS MER