Sökning: "High frequency approximations"

Visar resultat 1 - 5 av 28 avhandlingar innehållade orden High frequency approximations.

  1. 1. Computational electromagnetics software development and high frequency modeling of surface currents on perfect conductors

    Detta är en avhandling från Stockholm : KTH

    Författare :Sandy Sefi; KTH.; [2005]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; High frequency approximations; Maxwell’s equations; Method of Moments; Physical Optics; Geometrical Theory of Diffraction; Extraction Extrapolation; MATHEMATICS Applied mathematics Numerical analysis; MATEMATIK Tillämpad matematik Numerisk analys;

    Sammanfattning : In high frequency computational electromagnetics, rigorous numerical methods be come unrealistic tools due to computational demand increasing with the frequency. Instead approximations to the solutions of the Maxwell equations can be employed to evaluate th electromagnetic fields. LÄS MER

  2. 2. High-order finite difference approximations for hyperbolic problems multiple penalties and non-reflecting boundary conditions

    Detta är en avhandling från Linköping : Linköping University Electronic Press

    Författare :Hannes Frenander; Linköpings universitet.; Linköpings universitet.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : In this thesis, we use finite difference operators with the Summation-By-Partsproperty (SBP) and a weak boundary treatment, known as SimultaneousApproximation Terms (SAT), to construct high-order accurate numerical schemes.The SBP property and the SAT’s makes the schemes provably stable. LÄS MER

  3. 3. Approximations of Integral Equations for WaveScattering

    Detta är en avhandling från Stockholm : Numerisk analys och datalogi (NADA), (tills m KTH)

    Författare :Andreas Atle; Stockholms universitet.; [2006]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Integral equations; Marching on in time; On surface radiation condition; Physical Optics; MATHEMATICS Applied mathematics Numerical analysis; MATEMATIK Tillämpad matematik Numerisk analys;

    Sammanfattning : Wave scattering is the phenomenon in which a wave field interacts with physical objects. An incoming wave is scattered at the surface of the object and a scattered wave is produced. Common practical cases are acoustic, electromagnetic and elastic wave scattering. LÄS MER

  4. 4. Perfectly Matched Layers and High Order Difference Methods for Wave Equations

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Kenneth Duru; Uppsala universitet.; Uppsala universitet.; [2012]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis; Elastic waves; Surface waves; Perfectly matched layers; High order difference methods; Stability; Summation-by-parts operators; Boundary treatments;

    Sammanfattning : The perfectly matched layer (PML) is a novel technique to simulate the absorption of waves in unbounded domains. The underlying equations are often a system of second order hyperbolic partial differential equations. In the numerical treatment, second order systems are often rewritten and solved as first order systems. LÄS MER

  5. 5. Liquidity and Portfolio Optimisation

    Detta är en avhandling från Birmingham : Aston University

    Författare :Björn Hagströmer; [2009]
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; stock market; liquidity; systematic liquidity; portfolio optimisation; high-frequency data; SOCIAL SCIENCES Business and economics Economics; SAMHÄLLSVETENSKAP Ekonomi Nationalekonomi;

    Sammanfattning : This thesis presents research within empirical financial economics with focus on liquidity and portfolio optimisation in the stock markets. The discussion on liquidity is focussed on measurement issues, including TAQ data processing and measurement of systematic liquidity factors. LÄS MER