Sökning: "linear and nonlinear waves"

Visar resultat 6 - 10 av 50 avhandlingar innehållade orden linear and nonlinear waves.

1. 6. Transient waves in nonstationary media : with applications to lightning and nonlinear media

   Författare :Ingegerd Åberg; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; lightning; Klein-Gordon; nonlinear; characteristics; wave splitting; imbedding; sources; propagators; Green functions; direct and inverse scattering; Nonstationary; transient; high-frequency switching; Kerr.; Technological sciences; Teknik;

   Sammanfattning : Propagation of transient waves in nonstationary, inhomogeneous, dispersive, stratified media is considered. Waves originating from sources exterior to the scatterer as well as from internal sources are treated. Algorithms are developed and illustrated by computations of wave phenomena in stationary, nonstationary and weakly nonlinear media. LÄS MER

3. 7. Transport Barriers in Plasmas and Fluids

   Författare :Robert Moestam; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DNS; transport barriers; Zonal flows; L-H mode transition; turbulence simulations; drift waves; flux tube simulations; nonlinear instabilities; linear instabilities;

   Sammanfattning : In the present work different mechanisms for generation and suppression of turbulence are studied. The suppression of nonlinearly generated turbulence stabilized by temperature boundary conditions as well as turbulence generated by linear instabilities and suppressed by nonlinearly generated secondary flows are treated. LÄS MER

4. 8. Steady waves in local and nonlocal models for water waves

   Författare :Tien Truong; Matematik (naturvetenskapliga fakulteten); []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics;

   Sammanfattning : We study the steady Euler equations for inviscid, incompressible, and irrotational water waves of constant density. The thesis consists of three papers. The first paper approaches the Euler equations through a famous nonlocal model equation for gravity waves, namely the Whitham equation. LÄS MER

5. 9. Wave Loads and Peak Forces on Moored Wave Energy Devices in Tsunamis and Extreme Waves

   Författare :Linnea Sjökvist; Malin Göteman; Mats Leijon; Peter Stansby; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; OpenFOAM; CFD; Wave power; Tsunami waves; Extreme waves; Offshore; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Surface gravity waves carry enormous amounts of energy over our oceans, and if their energy could be harvested to generate electricity, it could make a significant contribution to the worlds power demand. But the survivability of wave energy devices in harsh operating conditions has proven challenging, and for wave energy to be a possibility, peak forces during storms and extreme waves must be studied and the devices behaviour understood. LÄS MER

7. 10. Alfvén Waves and Energy Transformation in Space Plasmas

   Författare :Yuri Khotyaintsev; Kalevi Mursula; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; Alfvén waves; particle acceleration; ionosphere; magnetopause; magnetic reconnection; Rymd- och plasmafysik; Space physics; Rymdfysik; Space Physics; rymdfysik;

   Sammanfattning : This thesis is focused on the role of Alfvén waves in the energy transformation and transport in the magnetosphere. Different aspects of Alfvén wave generation, propagation and dissipation are considered. The study involves analysis of experimental data from the Freja, Polar and Cluster spacecraft, as well as theoretical development. LÄS MER