English
norskArtikler, rapporter og annet (fysikk og teknologi): Nye registreringer
Viser treff 1001-1020 av 1062
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First simultaneous measurements of waves generated at the bow shock in the solar wind, the magnetosphere and on the ground
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009) -
Particle precipitations during NEIAL events : simultaneous ground based observations at Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007)In this paper we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar (ESR). For the first time, long sequences of NEIALs are recorded, with more than 50 events within an hour, ranging from 6.4 to 140 s in duration. The events took place from ~08:45 to 10:00 UT, 22 January 2004. We combine ESR data with observations of optical aurora by a meridian scanning ... -
Ion-dispersion and rapid electron fluctuations in the cusp : a case study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008) -
Non-Gaussian Clustering of SAR images for Glacier Change Detection
(Conference object; Konferansebidrag, 2010) -
Time Series Investigation of Land Subsidence Using a Weighted Least Squares Adjustment Based on Image Mode Interferometric Data
(Conference object; Konferansebidrag, 2010)This study presents the weighted least squares method based on Interferometric Synthetic Aperture Radar (InSAR) images to retrieve spatial-temporal evolution of land subsidence in Mashhad Valley, northeast Iran. Using the analysis of a few interferograms covering the 2003-2005 period, Motagh et al (GJI 2006) presented a preliminary analysis of the subsidence in this area. Here we extend this study ... -
Optical trapping and propulsion of red blood cells on waveguide surfaces
(Journal article; Tidsskriftartikkel; Peer reviewed, 2010) -
"Intelligente" læringssystemer: Fra leken Furby til spamfiltre til miljø
(Conference object; Konferansebidrag, 2010-09-02) -
On the relationship between auroral absorption, electrojet currents and plasma convection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009-02-02)In this study, the relationship between auroral absorption, electrojet currents, and ionospheric plasma convection velocity is investigated using a series of new methods where temporal correlations are calculated and analysed for different events and MLT sectors. We employ cosmic noise absorption (CNA) observations obtained by the Imaging Riometer for Ionospheric Studies (IRIS) system in ... -
Climatic trends in E-region critical frequency and virtual height above Tromsø (70 degrees N, 10 degrees E)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007-11-29)We have examined the long time series of observations of E-region virtual height (1948–2006) and critical frequency (1935-2006) hitherto made by the Tromsø ionosonde at 70 degrees N, 19 degrees E. Combining a simplistic trend analysis with a rigorous treatment of errors we identify a negative trend in critical frequency. While a similar analysis of the virtual height h'E also suggests a negative ... -
Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009-01-08)Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency fH was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency ... -
Generation of the lower-thermospheric vertical wind estimated with the EISCAT KST radar at high latitudes during periods of moderate geomagnetic disturbance
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008-06-11)Lower-thermospheric winds at high latitudes during moderately-disturbed geomagnetic conditions were studied using data obtained with the European Incoherent Scatter (EISCAT) Kiruna-Sodankylä-Tromsø (KST) ultrahigh frequency (UHF) radar system on 9–10 September 2004. The antenna-beam configuration was newly designed to minimize the estimated measurement error of the vertical neutralwind speed in the ... -
Dataverktøy til regning, skriving og tegning i naturfag
(Book; Bok, 2007) -
Fysikk i den polare atmosfæren og nordlyset
(Research report; Forskningsrapport, 2008)Den polare atmosfæren har fått mer oppmerksomhet i den senere tid enn den vanligvis har vært forunt. Dette henger sammen med tanken om at den er så ren og upåvirket av eventuelle forurensninger som vi pumper ut i atmosfæren i de mer urbane strøk. Dersom atmosfæren tar skade av denne aktiviteten, forventer en å se skadevirkningene først og klarest i den polare atmosfæren. Svekkelsen av ozonlaget ... -
Three photometric methods tested on ground-based data of Q 2237+0305
(Journal article; Tidsskriftartikkel; Peer reviewed, 1998-09-09)The Einstein Cross, Q 2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse the data: an automatic image decomposition technique, a CLEAN algorithm and the new MCS deconvolution code. The photometric and astrometric results obtained with the three methods are presented. ... -
Burst statistics of fluctuations in a simple magnetized torus configuration
(Working paper; Arbeidsnotat, 2009-04-19)In a toroidal plasma confined by a purely toroidal magnetic field the plasma transport is governed by electrostatic turbulence driven by the flute interchange instability on the low-field side of the torus cross section. In this paper we revisit experimental data obtained from the Blaamann torus at the University of Tromso. On time-scales shorter than the poloidal rotation time, the time series of ... -
Self-similar transport processes in a two-dimensional realization of multiscale magnetic field turbulence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2004-12-14)We present the results of a numerical investigation of charged-particle transport across a synthesized magnetic configuration composed of a constant homogeneous background field and a multiscale perturbation component simulating an effect of turbulence on the microscopic particle dynamics. Our main goal is to analyze the dispersion of ideal test particles faced to diverse conditions in the turbulent ... -
Electron fishbones: theory and experimental evidence
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007-07-19)We discuss the processes underlying the excitation of fishbone-like internal kink instabilities driven by supra-thermal electrons generated experimentally by different means: Electron Cyclotron Resonance Heating (ECRH) and by Lower Hybrid (LH) power injection. The peculiarity and interest of exciting these electron fishbones by ECRH only or by LH only is also analyzed. Not only the mode stability ... -
The WSO, a world-class observatory for the ultraviolet
(Conference object; Konferansebidrag, 2002-09-17)The World Space Observatory is an unconventional space project proceeding via distributed studies. The present design, verified for feasibilty, consists of a 1.7-meter telescope operating at the second Largangian point of the Earth-Sun system. The focal plane instruments consist of three UV spectrometers covering the spectral band from Lyman alpha to the atmospheric cutoff with R~55,000 and offering ... -
HS 0705+6700: a new eclipsing sdB binary
(Journal article; Tidsskriftartikkel, 2001-10-09)We report the discovery of an eclipsing binary – HS 0705+6700 – being an sdB star with a faint companion. From its light curve the orbital period of 8263.87 s, the mass ratio of the system q = 0.28, the inclination of 84.◦4 and other system parameters are derived. The companion does not contribute to the optical light of the system except through a strong reflection effect. The semiamplitude of ... -
The optical afterglow and host galaxy of GRB 000926
(Journal article; Tidsskriftartikkel, 2001-04-11)We present the discovery of the Optical Transient (OT) of the long–duration gamma-ray burst GRB 000926. The optical transient was detected independently with the Nordic Optical Telescope and at Calar Alto 22.2 hours after the burst. At this time the magnitude of the transient was R = 19.36. The transient faded with a decay slope of about 1.7 during the first two days after which the slope increased ...
