Sökning: "electromagnetic waves"

Visar resultat 1 - 5 av 122 avhandlingar innehållade orden electromagnetic waves.

1. 1. Transient Electromagnetic Waves in Nonlinear Media

   Författare :Daniel Sjöberg; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signal processing; nonlinear materials; Electromagnetic waves; instantaneous response; waveguides; shock waves; entropy condition; Elektronik och elektroteknik; Electronics and Electrical technology; Signalbehandling; Electromagnetism; optics; acoustics; Elektromagnetism; optik; akustik;

   Sammanfattning : This thesis is concerned with the propagation of transient electromagnetic waves in nonlinear media. It consists of a General Introduction and five scientific papers. The General Introduction gives a broad overview of nonlinear electromagnetic phenomena. LÄS MER

3. 2. Interaction between Electromagnetic Waves and Localized Plasma Oscillations

   Författare :Jan-Ove Hall; Thomas Leyser; Jan Trulsen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; space physics; plasma physics; radio waves; ionospheric modification; density depleations; field-aligned irregularities; lower hybrid solitary structures; lower hybrid cavities; Z mode waves; magnetosonic waves; scattering; mode conversion; Rymd- och plasmafysik; Space physics; Rymdfysik;

   Sammanfattning : This thesis treats interaction between electromagnetic waves and localized plasma oscillations. Two specific physical systems are considered, namely artificially excited magnetic field-aligned irregularities (striations) and naturally excited lower hybrid solitary structures (LHSS). LÄS MER

4. 3. 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

5. 4. Design and Characterization of Functional Structures for Electromagnetic Waves

   Författare :Andreas Ericsson; Teoretisk elektroteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electromagnetic scattering; functional structure; circular polarization selective structure; reflector antenna; electromagnetic absorber; radar cross section; compressive sensing; triaxial weave; homogenization; physical optics;

   Sammanfattning : This dissertation deals with design and characterization of functional structures for scattering of electromagnetic waves. An abundance of these structures can be found in nature, such as the structural coloration in the feathers of a peacock, the scales of butterflies and the shell of scarab beetles. LÄS MER

7. 5. Gravitational perturbations in plasmas and cosmology

   Författare :Mats Forsberg; Gert Brodin; Michael Bradley; Christopher Clarkson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; general relativity; cosmology; gravitational waves; plasma; electromagnetic waves; nonlinear waves; Plasma physics; Plasmafysik; Theory of relativity; gravitation; Relativitetsteori; gravitation; Cosmology; Kosmologi; teoretisk fysik; Theoretical Physics;

   Sammanfattning : Gravitational perturbations can be in the form of scalars, vectors or tensors. This thesis focuses on the evolution of scalar perturbations in cosmology, and interactions between tensor perturbations, in the form of gravitational waves, and plasma waves. LÄS MER