Sökning: "Diffraction theory"

Visar resultat 11 - 15 av 100 avhandlingar innehållade orden Diffraction theory.

  1. 11. Elastic Wave Scattering by Cracks - Interfacial Forces and High Frequency Diffraction

    Författare :Gert Persson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrasonic testing; Wiener-Hopf calculations; Geometrical Theory of Diffraction; edge diffracted body waves; PEDGE; two-dimensional diffraction; geometrical elastodynamic waves;

    Sammanfattning : This thesis treats elastic wave scattering by cracks with interfacial forces. The results are of practical interest in ultrasonic testing and includes development of numerical methods used to predict such testing. First the canonical problem of two-dimensional (2-D) diffraction from a semi-infinite crack is solved. LÄS MER

  3. 12. Thin Layers in Elastic Wave Propagation -Effective Modelling and Diffraction

    Författare :Peter Bövik; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Geometrical Theory of Diffraction; elastic wave scattering; shear waves; Wienr-Hopf method; L-TV waves; applications;

    Sammanfattning : In the present thesis, the interest is focussed on the problem of effective modelling of thin interface layers for applications in elastic wave scattering. The layers are considered to be thin compared with wavelengths involved and it is shown that when all effects to lowest order in the layer thickness are included, we get boundary conditions (BCs) which have a number of nice features, including the one of implying that no scattering occurs when the layer has material parameters identical to the ones in the matrix medium. LÄS MER

  4. 13. Structure, Dynamics and Thermodynamics of Liquid Water : Insights from Molecular Simulations

    Författare :Kjartan Thor Wikfeldt; Lars G. M. Pettersson; Francesco Sciortino; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Liquid water; supercooled water; diffraction; structure modeling; molecular dynamics; x-ray spectroscopy; EXAFS; SAXS; Physics; Fysik; Theoretical Physics; teoretisk fysik;

    Sammanfattning : Water is a complex liquid with many unusual properties. Our understanding of its physical, chemical and biological properties is greatly advanced after a century of dedicated research but there are still many unresolved questions. LÄS MER

  5. 14. Diode laser spectroscopy in extended wavelength ranges

    Författare :Ulf Gustafsson; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diode-laser spectroscopy; frequency-modulation spectroscopy; frequency conversion; fluorescence spectroscopy; scattering; diffraction; Fysicumarkivet A:2000:Gustafsson; Atomic and molecular physics; Atom- och molekylärfysik; absorption spectroscopy;

    Sammanfattning : Diode laser spectroscopy performed in the ultraviolet, visible and infrared spectral regions is presented. The accessible wavelength range for visible and near-infrared diode lasers is extended by the use of sum- and difference-frequency generation. LÄS MER

  7. 15. Tunable photonic crystals based on carbon nanofibers

    Författare :Robert Rehammar; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; FDTD; PECVD; Photonic crystal; carbon nanofiber; tunable; diffraction; ellipsometry;

    Sammanfattning : Photonic crystals are materials with periodically varying refractive indices. In conventional photonic crystal design it is hard to achieve tunable structures in the visible range, i.e. structures with changeable optical properties. LÄS MER