Sökning: "geometry effects"

Visar resultat 1 - 5 av 410 avhandlingar innehållade orden geometry effects.

  1. 1. Automorphic forms and string theory: Small automorphic representations and non-perturbative effects

    Författare :Henrik Gustafsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; instantons; automorphic forms; automorphic representations; Eisenstein series; U-duality; non-perturbative effects; string theory;

    Sammanfattning : This compilation thesis stems from a project with the purpose of determining non-perturbative contributions to scattering amplitudes in string theory carrying important information about instantons, black hole quantum states and M-theory. The scattering amplitudes are functions on the moduli space invariant under the discrete U-duality group and this invariance is one of the defining properties of an automorphic form. LÄS MER

  3. 2. Geometry, Topology and Emergence in Moiré Systems

    Författare :Ahmed Abouelkomsan; Emil Johansson Bergholtz; Felix von Oppen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Moiré materials; Topological phases; Fractional Chern insulators; Quantum geometry; Quantum Hall effects; Theoretical Physics; teoretisk fysik;

    Sammanfattning : The experimental discovery of correlated insulators and superconductivity in highly tunable Van der Waals heterostructures, such as twisted bilayer graphene, has highlighted the role of moiré patterns, resulting from tiny relative twists or lattice constant mismatches, in realizing strongly correlated physics. A key ingredient is the existence of very narrow flat bands where interaction effects are dominant. LÄS MER

  4. 3. Fatigue strength of welds in 800 MPa yield strength steels : Effects of weld toe geometry and residual stress

    Författare :Ebrahim Harati; Lars-Erik Svensson; Leif Karlsson; Högskolan Väst; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fatigue strength; Residual stress; Welds; Weld toe geometry; High strength steel; Weld Impression Analysis; Laser Scanning Profiling; Structured Light Projection; Manufacturing and materials engineering; Produktions- och materialteknik;

    Sammanfattning : Nowadays there is a strong demand for lighter vehicles in order to increase the pay load. Through this the specific fuel consumption is decreased, the amount of greenhouse gases is lowered and the transport economy improved. One possibility to optimize the weight is to make the components from high strength steels and join them by welding. LÄS MER

  5. 4. Drift waves in non-circular tokamak geometry

    Författare :Johan Anderson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; tokamak geometry; instabilities; drift waves; fusion plasmas;

    Sammanfattning : One of the main concerns in fusion research is to understand the anomalously high transport in magnetically confined plasmas. In recent years, substantial progress in the understanding of transport in terms of drift waves in tokamaks has been achieved. LÄS MER

  7. 5. Quantum effects in nanoscale Josephson junction circuits

    Författare :Silvia Corlevi; David B. Haviland; Jukka Pekola; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Josephson junctions; Josephson junction arrays; electromagnetic environment; Cooper pair transistor; parity effects; Physics; Fysik;

    Sammanfattning : This thesis presents the results of an experimental study on single-charge effects in nanoscale Josephson junctions and Cooper pair transistors (CPTs). In nanoscale Josephson junctions the charging energy EC becomes significant at sub-Kelvin temperatures and single-charge effects, such as the Coulomb blockade of Cooper pair tunneling, influence the transport properties. LÄS MER