Sökning: "Frequency-domain"

Visar resultat 6 - 10 av 233 avhandlingar innehållade ordet Frequency-domain.

  1. 6. Diagnosis of Moisture in Transformer Insulation - Application of frequency domain spectroscopy

    Författare :Chandima Ekanayake; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; moisture content; diagnostic methods; modelling; polarisation depolarisation currents PDC ; frequency domain spectroscopy FDS ; dielectric response measurements; Oil-impregnated pressboard paper insulation; Karl Fischer titration KFT ; conductivity; ageing;

    Sammanfattning : This thesis presents application of dielectric response measurements for identifying condition of high voltage insulation in power transformers. Results of such measurements, incorporated with different modelling techniques, allow to estimate moisture content in solid part of transformer insulation. LÄS MER

  3. 7. Hybrid Methods for Computational Electromagnetics in Frequency Domain

    Författare :Stefan Hagdahl; Björn Engquist; Lars Pettersson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; Geometrical Theory of Diffraction; Smooth Surface Diffraction; Boundary Element Method; Hybrid methods; Electromagnetic Scattering; Numerical analysis; Numerisk analys;

    Sammanfattning : In this thesis we study hybrid numerical methods to be used in computational electromagnetics. The purpose is to address a wide frequency range relative to a given geometry. We also focus on efficient and robust numerical algorithms for computing the so called Smooth Surface Diffraction predicted by Geometrical Theory of Diffraction (GTD). LÄS MER

  4. 8. Iterative solution of Maxwell's equations in frequency domain

    Författare :Martin Nilsson; Per Lötstedt; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

    Sammanfattning : We have developed an iterative solver for the Moment Method. It computes a matrix–vector product with the multilevel Fast Multipole Method, which makes the method scale with the number of unknowns. The iterative solver is of Block Quasi-Minimum Residual type and can handle several right-hand sides at once. LÄS MER

  5. 9. Methods for Frequency Domain Estimation of Continuous-Time Models

    Författare :Jonas Gillberg; Lennart Ljung; Fredrik Gustafsson; Linköpings universitet; []
    Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : Approaching parameter estimation from the discrete-time domain is the dominating paradigm in system identification. Identification of continuous-time models on the other hand is motivated by the fact that modelling of physical systems often take place in continuous-time. LÄS MER

  7. 10. Optical Memories and Processing in Time- and Frequency Domain

    Författare :Baozhu Luo; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optical storage; photon echo; spectral hole burning; nonlinear optics; fiber amplifier; logical operation; phase retrieval; polarization holographic recording and retrieval; optical processing; Atomic and molecular physics; Atom- och molekylärfysik; Fysicumarkivet A:1998:Luo;

    Sammanfattning : Spectral hole burning and photon echoes are the techniques for frequency-selective optical memories, which have the potential to increase areal data storage density by a factor 10**7. They also have the capability to perform in-memory data processing. LÄS MER