Search for dissertations about: "boundary elements"

Showing result 1 - 5 of 144 swedish dissertations containing the words boundary elements.

  1. 1. Rough surfaces in contact : artificial intelligence and boundary lubrication

    Author : Marco Rapetto; Luleå tekniska universitet; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Machine Elements; Maskinelement;

    Abstract : Interacting surfaces are found in mechanical systems and components. Since engineered surfaces are not perfectly smooth, only a fraction of the nominal surface area is actually in contact. This fraction is denoted as the real area of contact, Ar, and is formed by the sum of the contact spots between the two touching surfaces. READ MORE

  2. 2. Wave Splitting and Effective Boundary Conditions for Structural Elements

    Author : Martin Johansson; Chalmers University of Technology; []
    Keywords : approximate boundary condition; Mindlin plate; Timoshenko beam; thin plates; cylindrical coordinates; series approximation; wave splitting; dispersion; fluid-loaded plate; Biot;

    Abstract : The subject of this thesis is twofold. The first part concerns the wave splitting of structural elements. The second part concerns approximate boundary conditions for fluid-loaded thin plates. Wave splitting is a mathematical tool for the formulation of scattering problems in the time domain that aims at solving inverse problems, e. READ MORE

  3. 3. Boundary lubrication in screw-nut transmissions

    Author : Lars O. Ekerfors; Luleå tekniska universitet; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinelement; Machine Elements;

    Abstract : This report deals with the function of screw-nut transmissions (powerscrews). Two aspects of this function have been investigated. Owing to different running parameters, primarily sliding speed and average pressure between the sliding surfaces of the thread, the coefficient of friction and the efficiency will vary within wide limits. READ MORE

  4. 4. Boundary layer streaks as a novel laminar flow control method

    Author : Sohrab Sattarzadeh Shirvan; Jens H. M. Fransson; Edward B. White; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer stability; laminar to turbulent transition; laminar flow control; drag reduction; Tollmien-Schlichting waves; oblique waves; streaky boundary layers; miniature vortex generators; discrete suction;

    Abstract : A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. READ MORE

  5. 5. Geochemical and sedimentary signatures of Phanerozoic events

    Author : Jane Wigforss-Lange; Berggrundsgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; geokemi; Sedimentology; Petrology; mineralogy; geochemistry; Petrologi; mineralogi; Carbon and oxygen isotopes; Jurassic-Cretaceous boundary; K-T boundary; Late Silurian; Events; Trace elements; Sedimentologi;

    Abstract : Geological and biological catastrophic events have occurred repeatedly in the Earth's history, leaving traces in the global stratigraphical record in the form of sedimentary features, geochemical anomalies and biotic turnovers. This thesis focuses on the sedimentological and geochemical signatures of several key events in the Phanerozoic stratigraphical record, and aims to interpret the different signals and the causal mechanisms behind each of these events. READ MORE