Sökning: "wave propagation"

Visar resultat 11 - 15 av 347 avhandlingar innehållade orden wave propagation.

  1. 11. Wireless Sensor Network and Radio Wave Propagation in Harsh Environments

    Författare :Mathias Grudén; Anders Rydberg; Erik Björnemo; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wireless Sensor Network; WISENET; Wave Propagation; Radio Communication; Harsh Environmnents; Engineering Science with specialization in Microwave Technology; Teknisk fysik med inriktning mot mikrovågsteknik;

    Sammanfattning : This licentiate thesis cover two important subjects regarding the application of wireless sensor networks (WSNs). Both subjects are related to propagation mechanisms. The first subject is what the radio channel looks like and how it behaves. LÄS MER

  3. 12. Nonlinear interaction and propagation of gravitational and electromagnetic waves in plasmas

    Författare :Martin Servin; Gert Brodin; Lennart Stenflo; Demetrios Papadopoulos; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical physics; general relativity; plasma; gravitational waves; electromagnetic waves; nonlinear; wave interaction; wave propagation; Teoretisk fysik; Physics; Fysik; teoretisk fysik; Theoretical Physics;

    Sammanfattning : Gravitational waves and electromagnetic waves are important as carriers of energy and information. This thesis is devoted to the study of the propagation and interaction of these waves in plasmas, with emphasis on nonlinear effects and applications within astrophysics. LÄS MER

  4. 13. Summation-by-Parts Finite Difference Methods for Wave Propagation and Earthquake Modeling

    Författare :Vidar Stiernström; Ken Mattsson; Mark H. Carpenter; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Finite difference method; high-order accuracy; stability; summation-by-parts; wave propagation; earthquake modeling; inverse problems; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : Waves manifest in many areas of physics, ranging from large-scale seismic waves in geophysics down to particle descriptions in quantum physics. Wave propagation may often be described mathematically by partial differential equations (PDE). Unfortunately, analytical solutions to PDEs are in many cases notoriously difficult to obtain. LÄS MER

  5. 14. Finite Difference Methods for Time-Dependent Wave Propagation Problems

    Författare :Ylva Ljungberg Rydin; Ken Mattsson; Erik Sjöqvist; Magnus Svärd; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Finite differences; Wave propagation problems; Summation-by-parts; Simultaneous approximation term; High-order accuracy; Deforming domains; Point sources; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : Wave propagation models are essential in many fields of physics, such as acoustics, electromagnetics, and quantum mechanics. Mathematically, waves can be described by partial differential equations (PDEs).  In most cases, exact solutions to wave-dominated PDEs are nearly impossible to derive. LÄS MER

  7. 15. Material distribution-based topology optimization for wave propagation problems

    Författare :Ahmad Hasnain Bokhari; Eddie Wadbro; Martin Berggren; Roland Herzog; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; topology optimization; material distribution; wave propagation problems; Helmholtz equation; acoustics; electromagnetics; plasmonics;

    Sammanfattning : This thesis employs material distribution-based topology optimization for wave propagation problems. In the material distribution approach, we define a material indicator function that models the presence and absence of material in a design domain. LÄS MER