Search for dissertations about: "surface acoustic waves"

Showing result 16 - 20 of 41 swedish dissertations containing the words surface acoustic waves.

  2. 16. Scattering of Elastic Waves by Inhomogeneities in Cylindrical Structures

    Author : Sune Olsson; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Abstract : In the present thesis we extend the null field approach (in the literature also often referred to as "the T matrix method" or "the extended boundary condition method") to some new multiple scattering problems involving infinite cylindrical surfaces and a bounded obstacle. The first case considered is the scattering of acoustic waves by a bounded obstacle outside an infinite cylinder of constant cross section. READ MORE

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

    Author : Andreas Ericsson; Teoretisk elektroteknik; []
    Keywords : 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;

    Abstract : 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. READ MORE

  5. 18. Interaction between electronic and vibrational edge states in graphene

    Author : Anton Vikström; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; collective excitations; quantum acous- tics; quantum Hall effect; edge waves; graphene; solitons;

    Abstract : A sheet of graphene in a magnetic field perpendicular to the sheet has electronic edge states with nonzero velocities. These edge states are localized to the edge of the sheet on the order of the magnetic length. READ MORE

  6. 19. Analysis, Control, and Design Optimization of Engineering Mechanics Systems

    Author : Esubalewe Lakie Yedeg; Martin Berggren; Eddie Wadbro; Anton Evgrafov; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Topology optimization; Helmholtz equation; acoustic impedance; anisotropic filter; thin structures; finite element method; Nitsche-type method; interface problem; Optimal control; adjoint method; business data processing; administrativ databehandling;

    Abstract : This thesis considers applications of gradient-based optimization algorithms to the design and control of some mechanics systems. The material distribution approach to topology optimization is applied to design two different acoustic devices, a reactive muffler and an acoustic horn, and optimization is used to control a ball pitching robot. READ MORE

  7. 20. On stability and receptivity of boundary-layer flows

    Author : Nima Shahriari; Ardeshir Hanifi; Dan S. Henningson; Peter J. Schmid; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer receptivity; acoustic receptivity; swept-wing flow; crossflow vortices; roughness element; global stability analysis; direct numerical simulation; plasma actuator; Engineering Mechanics; Teknisk mekanik;

    Abstract : This work is concerned with stability and receptivity analysis as well as studies on control of the laminar-turbulent transition in boundary-layer flows through direct numerical simulations. Various flow configurations are considered to address flow around straight and swept wings. READ MORE