Sökning: "transient wave propagation"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden transient wave propagation.

1. 1. Wave Propagation in Structural Elements - Direct and Inverse Problems in the Time Domain

   Författare :Peter Folkow; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integro-differential equations; non-uniform beams; wave splitting; wave propagator; finite difference; Timoshenko beam; imbedding; Mindlin plate; inverse problem; viscoelastic damping; nonlinear rod; transient wave propagation; Green function;

   Sammanfattning : The subject of this thesis is direct and inverse wave propagation problems in structural elements. The considered structures are beams, plates and rods. The models for the beams and the plates are based on linear theory, while the rods are assumed to be nonlinear. The greater part of the work concerns the Timoshenko beam. LÄS MER

3. 2. Transient electromagnetic pulse propagation in temporally dispersive materials

   Författare :Igor Egorov; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Green functions; direct scattering; time domain; wave propagation; bi-gyrotropic; chiral; bi-isotropic; Forerunner; precursor; Green dyadics; Electronics and Electrical technology; Elektronik och elektroteknik;

   Sammanfattning : This thesis treats the problem of transient electromagnetic pulse propagation in temporally dispersive media. The analysis is performed using time-domain techniques. In particular, the dispersive wave splitting which decouples the Maxwell equations both in vacuum and inside the medium is utilized. LÄS MER

4. 3. Scattering on the Timoshenko Beam. Direct and Inverse Problems in the Time Domain

   Författare :Dag V. J. Billger; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integro-differential equations; wave splitting; transient wave propagation; viscoelastic damping; wave propagators; inverse problems; scattering operators; Timoshenko beam; non-uniform beams; imbedding;

   Sammanfattning : This thesis concerns the use of time domain methods for treating direct and inverse scattering problems for flexural waves on beams. The Timoshenko equation is used throughout to describe the behaviour of such waves. LÄS MER

5. 4. Identification of Viscoelastic Materials by Use of Wave Propagation Methods

   Författare :Saed Mousavi; Bengt Lundberg; Urmas Valdek; Janne Färm; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; Identification; Viscoelastic; Complex modulus; Complex Poisson s ratio; wave; Impact; Teknisk fysik; Engineering physics; Teknisk fysik;

   Sammanfattning : Complex moduli and Poisson’s ratio have been estimated using extensional and torsional wave experiments. The data were used for assessment of linearity and isotropy of two polymers, polymethyl methacrylate (PMMA) and polypropylene (PP). The responses of both materials were found to be close to linear and isotropic. LÄS MER

7. 5. 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