Institutt for fysikk og teknologi: Nye registreringer

Viser treff 1421-1428 av 1428

    • Observations of thermospheric neutral winds within the polar cusp and the auroral oval using a Doppler imaging system (DIS). 

      Henriksen, K.; Rees, D.; Smith, R.W.; Signernes, F.; Brandstrom, U.; Harris, M.; Maskall, G. (Journal article; Tidsskriftartikkel, 1998)
      Two Doppler imaging systems (DIS) or wide-field imaging Fabry-Perot interferometers (FPI), have recently been commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard, and the second at the IRF, Kiruna, Sweden. These instruments can provide wide-field (600 * 800 km) images of neutral wind flows in the upper thermosphere, by measuring the Doppler shift of the atomic oxygen forbidden ...

    • Superposed epoch analysis applied to large-amplitude travelling convection vortices. 

      Hansen, T.L.; Lühr, H.; Rother, M.; Iyemori, T.; Lepping, R.P. (Journal article; Tidsskriftartikkel, 1998)
      For the six months from 1 October 1993 to 1 April 1994 the recordings of the IMAGE magnetometer network have been surveyed in a search for large- amplitude travelling convection vortices (TCVs). The restriction to large amplitudes (>100 nT) was chosen to ensure a proper detection of evens also during times of high activity. Readings of all stations of the northern half of the IMAGE network ...

    • The harmonizable representation of complex-valued nonstationary random processes 

      Hindberg, Heidi (Master thesis; Mastergradsoppgave, 2005-06-14)
      In this thesis we study the second-order statistical moment functions that characterizes complex-valued harmonizable processes. A real-valued harmonizable process has four Hermitian second-order functions. These functions are equivalent representations of the second-order statistical quantities of the process. For a complex-valued harmonizable process, however, we need the complementary functions ...

    • Observations of auroral plasma lines 

      Grydeland, Tom (Master thesis; Mastergradsoppgave, 1998-03-01)
      The thesis describes observations of strongly enhanced incoherent scatter plasma lines in the auroral ionosphere which were made with the EISCAT UHF radar in 1985. The linear theory of plasma instabilities is reviewed, and several possible explanations are discussed. The observations were found to be of insufficient resolution to unambiguously resolve which one would be the correct explanation. ...

    • Low-frequency noise power spectrum density characterizing of SiGe HBTs 

      Qi, Peng (Master thesis; Mastergradsoppgave, 2006-06-06)
      The main purposes of this thesis are the Low-Frequency Noise measurement of Silicon-Germanium Heterojunction Bipolar Transistors and its Power Spectrum Density Characterizing. The new generation 375 GHZ SiGe HBTs were measured in this work. We show that most of PSDs of the new generation SiGe HBTs have very ”bumpy” spectra which is contributed by GR noise sources. We investigated their basic ...

    • Statistical modelling of polarimetric SAR data 

      Doulgeris, Anthony Paul (Master thesis; Mastergradsoppgave, 2006-06-02)
      A statistical modelling technique is developed to analyse polarimetric synthetic aperture radar (PolSAR) images. Polarimetric SAR data consists of four complex scattering coefficients at each image location, requiring multivariate modelling techniques, and this work focuses on a simple class of multivariate distributions, the scale mixture of Gaussians. Three parametric model families of that ...

    • A detection theoretical approach to digital communications using autoregressive process shift keying 

      Anfinsen, Stian Normann (Master thesis; Mastergradsoppgave, 2001-03-10)
      I klassisk digital kommunikasjon overføres en bitstrøm gjennom en kanal ved å modulere parametrene til en deterministisk bærebølge. Noen kjente eksempler er amplitudemodulasjon (AM), frekvensmodulasjon (FM) og fasemodulasjon (PM). Mottakeren estimerer parametrene til det informasjonsbærende signalet og bruker en deteksjonsregel til å klassifisere den mottatte bølgeformen som en av flere mulige ...

    • Mikrobølgeradiometri anvendt til deteksjon av temperaturgradienter i brystvevsfantom 

      Klemetsen, Øystein (Master thesis; Mastergradsoppgave, 2006-06-01)
      En passiv, ikke-invasiv og ufarlig metode for detektering av brystkreft er motivasjonen for denne oppgaven. Basisen for mikrobølgeteori og radiometrisk teori er presentert. Videre presenteres grunnlaget for å kunne foreta passive målinger på brystvevsmodeller, målemetoder og forbedringsmuligheter innen mikrobølge radiometri. Vi studerer ulike forbedringsmuligheter ved å se på systemet ved Institutt ...