Search for dissertations about: "Björn Engquist"

Showing result 1 - 5 of 10 swedish dissertations containing the words Björn Engquist.

2. 1. Modified Stencils for Boundaries and Subgrid Scales in the Finite-Difference Time-Domain Method

   Author : Jon Häggblad; Björn Engquist; Olof Runborg; Björn Sjögreen; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; FDTD; Yee; Staircasing;

   Abstract : This thesis centers on modified stencils for the Finite-Difference Time-Domain method (FDTD), or Yee scheme, when modelling curved boundaries, obstacles and holes smaller than the discretization length.  The goal is to increase the accuracy while keeping the structure of the standard method, enabling improvements to existing implementations with minimal effort. READ MORE

4. 2. Boundary and Interface Conditions for Electromagnetic Wave Propagation using FDTD

   Author : Jon Häggblad; Björn Engquist; Olof Runborg; Thomas Rylander; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Numerical analysis; Numerisk analys;

   Abstract : Simulating electromagnetic waves is of increasing importance, for example, due to the rapidly growing demand of wireless communication in the fields of antenna design, photonics and electromagnetic compatibility (EMC). Many numerical and asymptotic techniques have been developed and one of the most common is the Finite-Difference Time-Domain (FDTD) method, also known as the Yee scheme. READ MORE

5. 3. Approximations of Integral Equations for WaveScattering

   Author : Andreas Atle; Björn Engquist; Richard Tsai; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Integral equations; Marching on in time; On surface radiation condition; Physical Optics; Numerical analysis; Numerisk analys;

   Abstract : 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. READ MORE

6. 4. Hybrid Methods for Computational Electromagnetics in Frequency Domain

   Author : Stefan Hagdahl; Björn Engquist; Lars Pettersson; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; Geometrical Theory of Diffraction; Smooth Surface Diffraction; Boundary Element Method; Hybrid methods; Electromagnetic Scattering; Numerical analysis; Numerisk analys;

   Abstract : In this thesis we study hybrid numerical methods to be used in computational electromagnetics. The purpose is to address a wide frequency range relative to a given geometry. We also focus on efficient and robust numerical algorithms for computing the so called Smooth Surface Diffraction predicted by Geometrical Theory of Diffraction (GTD). READ MORE

7. 5. Multiscale Methods for Wave Propagation Problems

   Author : Henrik Holst; Björn Engquist; Olof Runborg; Assyr Abdulle; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : Simulations of wave propagation in heterogeneous media and at high frequencies are important in many applications such as seismic-, {electro-magnetic-,} acoustic-, fluid flow problems and others. These are classical multiscale problems and often too computationally expensive for direct numerical simulation. READ MORE