Sökning: "Tobias Hultqvist"

Hittade 3 avhandlingar innehållade orden Tobias Hultqvist.

  1. 1. Elastohydrodynamically lubricated finite line contacts operating under transient conditions

    Författare :Tobias Hultqvist; Roland Larsson; Lars-Erik Stacke; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinelement; Machine Elements;

    Sammanfattning : The effect of greenhouse gas emissions contributing to the global warming is today becoming an increasingly important problem worldwide and has led to increased efforts being made on improving tribological performance of interacting surfaces in mechanical systems. Due to increasingly stringent CO2regulations, a reduced fuel consumption has become a key area of interest for the automotive industry where low cost, low emission solutions are continuously developed and where low friction alternatives to machine elements currently in use are evaluated. LÄS MER

  3. 2. Transient elastohydrodynamic lubrication : Effects of geometry, surface roughness, temperature, and plastic deformation

    Författare :Tobias Hultqvist; Roland Larsson; Pär Marklund; Wassim Habchi; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinelement; Machine Elements;

    Sammanfattning : The urgent need to reduce greenhouse gas emissions in combination with an increased use of sustainable energy resources have led to immense efforts on improving energy efficiency of mechanical systems. Consequently, modern machine elements are typically lubricated with low viscosity oils and designed to endure an increasingly high power density. LÄS MER

  4. 3. Cadmium Free Buffer Layers and the Influence of their Material Properties on the Performance of Cu(In,Ga)Se2 Solar Cells

    Författare :Adam Hultqvist; Charlotte Platzer-Björkman; Tobias Törndahl; Marika Edoff; Takashi Minemoto; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cu In; Ga Se2; Solar cells; Thin film; Buffer layer; Window layer; ZnO; Zn O; S ; Zn; Mg O; Zn-Sn-O; Semiconductor physics; Halvledarfysik; Engineering Science with specialization in Solid State Physics; Teknisk fysik med inriktning mot fasta tillståndets fysik;

    Sammanfattning : CdS is conventionally used as a buffer layer in Cu(In,Ga)Se2, CIGS, solar cells. The aim of this thesis is to substitute CdS with cadmium-free, more transparent and environmentally benign alternative buffer layers and to analyze how the material properties of alternative layers affect the solar cell performance. LÄS MER