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norskInstitutt for fysikk og teknologi: Recent submissions
Now showing items 1301-1320 of 1428
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Ultrasound sensor for biomedical applications
(Master thesis; Mastergradsoppgave, 2011-12-15)Vesicoureteral reflux (VUR) is an abnormality that causes urine to flow back from the bladder to the kidneys, which may cause renal scarring and kidney damage. A non-ionizing and non-invasive VUR diagnostic technique, based on microwave hyperthermia, is under development. The possibility for improved hyperthermia efficiency and patient safety through implementation of ultrasound transducers is the ... -
Dust charging and density conditions deduced from observations of PMWE modulated by artificial electron heating
(Journal article; Tidsskriftartikkel; Peer reviewed, 2011)We present an analysis of relatively strong Polar Mesospheric Winter Echoes (PMWE) under artificial electron heating that changes the PMWE intensity. A major purpose is to find reliable estimates of the relaxation time of the heater modified PMWE to their undisturbed state during the heater switch-off phase; the implications regarding charge/discharge mechanisms; and to exploit the diagnostic potential ... -
Coordinated Cluster/Double Star and ground-based observations of dayside reconnection signatures on 11 February 2004
(Journal article; Tidsskriftartikkel; Peer reviewed, 2011)A number of flux transfer events (FTEs) were observed between 09:00 and 12:00UT on 11 February 2004, during southward and dawnward IMF, while the Cluster spacecraft array moved outbound through the northern, highaltitude cusp and dayside high-latitude boundary layer, and the Double Star TC-1 spacecraft was crossing the dayside low-latitude magnetopause into the magnetosheath south of the ecliptic ... -
Estimating production loss due to icing on wind turbines
(Master thesis; Mastergradsoppgave, 2011-06)Icing on wind turbines are known to lower their performance, but the exact relationship between wind, ice and power production is not known. In this thesis power loss due to icing on turbine blades at Aapua wind park is investigated for the winter season 2009-2010. The total loss is found to be 30%, whereof 25% is concluded being due to icing. Three different methods are presented to estimate ... -
Air temperature at 90 km altitude in the Artic obtained using meteor radar : validation, characterization and climate change.
(Master thesis; Mastergradsoppgave, 2011-09-30)Temperatures at 90 km altitude above Ramfjordmoen (69°N, 19°E) have been obtained with the Nippon/Norwegian Tromsø Meteor Radar. The temperatures have been derived from meteor radar decay rates using two techniques: the pressure based and the temperature gradient based methods. The results have been compared to the Microwave Limb Sounder (MLS) instrument on board the Aura spacecraft. It was found ... -
A K-Wishart Markov random field model for clustering of polarimetric SAR imagery
(Conference object; Konferansebidrag, 2011) -
On the measurement of subsonic flow in a capacitively coupled helicon plasma source
(Journal article; Tidsskriftartikkel; Peer reviewed, 2010)Plasma parameters and the subsonic flow from a capacitively coupled, cylindrical plasma source of the Njord helicon device are investigated by means of a Mach probe and a retarding field energy analyzer (RFEA). 13.56 MHz and 600 W RF power is inserted into the argon working gas under low-pressure conditions and moderate magnetic field. By means of a downstream field coil, the magnetic field is shaped ... -
A gas-hydrate related BSR on the W-Svalbard margin: distribution, geological control and formation mechanisms
(Master thesis; Mastergradsoppgave, 2011-06-15)A widespread bottom-simulating reflection (BSR) defining the base of the gas hydrate stability zone (BGHSZ) exists on seismic data from the western Svalbard margin, including the Vestnesa Ridge, which is a mounded and elongated sediment drift NW of Svalbard to the north of the Molloy Transform. The BSR stretches from the continental slope to within few km of the mid-oceanic ridge system thereby ... -
Fotoelektriske observasjonar av stjerneokkultasjonar ved måneranda
(Master thesis; Mastergradsoppgave, 1980-01)Analyser av okkultasjonskurvene frå fotoelektriske observasjonar viser at ein stor del av dei observerte stjernene er dobbelstjerner. Okkultasjonsteknikken kan lett åtskilje stjerner som har ein vinkelavstand større enn 0",01 og under gunstige tilhøve kan oppløysinga vere 0",001. I tillegg kan analysen av observasjonen gje vinkeldiameteren til stjerna dersom han er større enn 0",001. Utfrå ... -
Trapping of Nanoparticles with Optical Waveguides
(Master thesis; Mastergradsoppgave, 2011-05-18)Over the last few years, the notion that links optical trapping with strong intensity of light (high energy photon) not only forced the modification of optical tweezer, but it also open up the door for evanescent wave field trapping. While optical tweezer is merely suitable for trapping micro-sized particles, trapping by evanescent field of a channel waveguide enables both micro and nanosized particles ... -
Particle precipitation during NEIAL events : simultaneous ground based nighttime observations at Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009) -
Na lidar measurements during the ECOMA/Geminids campaign with focus on Na peak density and temperature
(Master thesis; Mastergradsoppgave, 2011-02)Using a resonance lidar, atomic Na (sodium) can be observed in the 80-110 km altitude range of the atmosphere. Na belongs to the alkali metal group and is highly reactive, so one could expect that it would quickly react with other particles and leave its atomic state. Its actual behaviour however includes the formation of relatively dense layers which, from the perspective of a stationary lidar, ... -
Marine Target Characteristics in Satellite SAR Imagery
(Master thesis; Mastergradsoppgave, 2011-02)In this thesis, marine targets in Synthetic Aperture Radar (SAR) imagery are studied. The appearance of different marine targets in different polarization channels, their scattering behaviour, and their contrast measures and geometric properties are investigated. RADARSAT-2 data containing ships, oil rigs and icebergs in ocean and/or sea ice background are evaluated. To be able to detect a target ... -
On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007) -
Remote Oxygen Sensing by Ionospheric Excitation (ROSIE)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009) -
First estimates of volume distribution of HF-pump enhanced emissions at 6300 and 5577 Å : a comparison between observations and theory
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008)We present bi-static observations of radio-wave induced optical emissions at 6300 and 5577 Å from a night-time radio-induced optical emission ionospheric pumping experiment at the HIPAS (Fairbanks) facility in Alaska. The optical observations were made at HIPAS and from HAARP located 285 km south-east. From these observations the altitude distribution of the emissions is estimated with tomography-like ... -
A study of fine structure of diffuse aurora with ALIS-FAST measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008)We present results of an investigation of the fine structure of the night sector diffuse auroral zone, observed simultaneously with optical instruments (ALIS) from the ground and the FAST electron spectrometer from space 16 February 1997. Both the optical and particle data show that the diffuse auroral zone consisted of two regions. The equatorward part of the diffuse aurora was occupied by a pattern ... -
F-region electron heating by X-mode radiowaves in underdense conditions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2009) -
A stochastic theory for temporal fluctuations in self-organized critical systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008) -
Spatial scaling of optical fluctuations during substorm-time aurora
(Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
