Search for dissertations about: "helmholtz"
Showing result 1 - 5 of 77 swedish dissertations containing the word helmholtz.
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1. Domain Decomposition and Preconditioned Iterative Methods for the Helmholtz Equation
Abstract : New preconditioned iterative solution methods for the Helmholtz equation are constructed. To evaluate the performance of the methods, two-dimensional problems with a waveguide geometry are used as model problems. Second- and fourth-order accurate finite difference discretizations are used. READ MORE
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2. Numerical methods for waveguide modelling
Abstract : Waveguides are used to transmit electromagnetic signals. Their geometry is typically long and slender. This particular shape can be used in the design of efficient computational methods. Only special modes are transmitted and eigenvalue and eigenvector analysis becomes important. READ MORE
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3. A Fast Method for Solving the Helmholtz Equation Based on Wave Splitting
Abstract : In this thesis, we propose and analyze a fast method for computing the solution of the Helmholtz equation in a bounded domain with a variable wave speed function. The method is based on wave splitting. The Helmholtz equation is first split into one--way wave equations which are then solved iteratively for a given tolerance. READ MORE
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4. The bowed string
Abstract : Of the many waveforms the bowed string can assume, theso-called "Helmholtz motion" (Helmholtz 1862) gives the fullestsound in terms of power and overtone richness. The developmentof this steady-state oscillation pattern can take manydifferent paths, most of which would include noise caused bystick-slip irregularities of the bow-string contact. READ MORE
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5. New Perspectives on Solar Wind-Magnetosphere Coupling
Abstract : The streaming plasma in the solar wind is a never ending source of energy, plasma, and momentum for planetary magnetospheres, and it continuously drives large-scale plasma convection systems in our magnetosphere and over our polar ionosphere. This coupling between the solar wind and the magnetosphere is primarily explained by two different processes: magnetic reconnection at high latitudes, which interconnects the interplanetary magnetic field (IMF) with the planetary dipole field, and low-latitude dynamos such as viscous interaction, where the streaming plasma in the solar wind may trigger waves and instabilities at the flanks of the magnetosphere, and thereby allow solar wind plasma to enter into the system. READ MORE