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    • Models for electrostatic drift waves with density variations along magnetic field lines 

      Garcia, Odd Erik; Pecseli, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Drift waves with vertical magnetic fields in gravitational ionospheres are considered where the unperturbed plasma density is enhanced in a magnetic flux tube. The gravitational field gives rise to an overall decrease of plasma density for increasing altitude. Simple models predict that drift waves with finite vertical wave vector components can increase in amplitude merely due to a conservation of ...
    • Intermittent fluctuations in the Alcator C-Mod scrape-off layer 

      Garcia, Odd Erik; Fritzner, Sindre Markus; Kube, Ralph; Cziegler, Istvan; LaBombard, Brian; Terry, Jim L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Fluctuations in the boundary region of the Alcator C-Mod tokamak have been analyzed using gas puff imaging data. It is found that the fluctuation amplitudes in the near scrape-off layer follow a normal distribution while the far scrape-off layer fluctuations are dominated by large amplitude bursts due to radial motion of blob-like structures and have a positively skewed and flattened amplitude ...
    • "Structure, composition, and dynamics of the middle atmosphere and lower ionosphere during a major meteor shower" 

      Hoppe, Ulf-Peter; Rapp, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
    • Development of the mesospheric Na layer at 69 degrees N during the Geminids meteor shower 2010 

      Dunker, Tim; Hoppe, Ulf-Peter; Stober, Gunter; Rapp, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper ...
    • Thermospheric atomic oxygen density estimates using the EISCAT Svalbard Radar 

      Vickers, Hannah; Kosch, M. J.; Sutton, E.; Ogawa, Y.; La Hoz, Cesar (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Coupling between the ionized and neutral atmosphere through particle collisions allows an indirect study of the neutral atmosphere through measurements of ionospheric plasma parameters. We estimate the neutral density of the upper thermosphere above ~250 km with the European Incoherent Scatter Svalbard Radar (ESR) using the year-long operations of the International Polar Year from March 2007 to ...
    • Geothermal energy and district heating in Ny-Ålesund, Svalbard 

      Iversen, Julianne (Master thesis; Mastergradsoppgave, 2013-12-13)
      This thesis presents the possibilities for using shallow geothermal energy for heating purposes in Ny-Ålesund. The current energy supply in Ny-Ålesund is a diesel generator, which does not comply with the Norwegian government and Ny-Ålesund Science Managers Committee’s common goal to maintain the natural environment in Ny-Ålesund. Ny-Ålesund has a potential for replacing the heat from the current ...
    • Wet snow detection by C-band SAR in avalanche forecasting 

      Hopsø, Ingrid Strømsvik (Master thesis; Mastergradsoppgave, 2013-12-15)
      Avalanches usually occur in steep, snow-covered mountain sides under special conditions. The stability of the snowpack depends, among other things, on the melting and freezing of the snowpack. If a snow covered area has not undergone a melt/freeze-process, it could potentially be unstable due to depth hoar or buried layers of frost, and therefore pose an avalanche risk if the area is located at a ...
    • Investigating robot navigation in health care with the Giraff telepresence robot 

      Kåven, Ove Henrik (Master thesis; Mastergradsoppgave, 2013-10-29)
      The Norwegian public healthcare system will not have the manpower to care for the elderly at the same level as now, unless technological solutions are found to make the most of the available manpower. This thesis investigates potential technologies for allowing the Giraff, a telepresence robot, to navigate and patrol an eldercare center autonomously, thus letting caregivers save time when checking ...
    • On the internal physical conditions in dust probes: transport, heating and evaporation of fragmented dust particles 

      Antonsen, Tarjei (Master thesis; Mastergradsoppgave, 2013-12-13)
      We study the conditions within, and dynamics of fragmented mesospheric dust particles inside, the Faraday-cup type dust probe MUDD using numerical simulations with a dedicated model. The transport of singly charged fragments from impacting NLC particles on the main grid in MUDD, have been calculated on the basis of supplementary models of the neutral gas conditions and electric field structure within ...
    • Serial Raman spectroscopy of particles trapped on a waveguide 

      Løvhaugen, Pål; Ahluwalia, Balpreet Singh; Huser, Thomas Rolf; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      We demonstrate that Raman spectroscopy can be used to characterize and identify particles that are trapped and propelled along optical waveguides. To accomplish this, microscopic particles on a waveguide are moved along the waveguide and then individually addressed by a focused laser beam to obtain their characteristic Raman signature within 1 second acquisition time. The spectrum is used to distinguish ...
    • Effects of Ocean Acidification and Warming on Sperm Activity and Early Life Stages of the Mediterranean Mussel (Mytilus galloprovincialis) 

      Vihtakari, Mikko; Hendriks, Iris E.; Holding, Johnna; Renaud, Paul E.; Duarte, Carlos M.; Havenhand, Jon N. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Larval stages are among those most vulnerable to ocean acidification (OA). Projected atmospheric CO2 levels for the end of this century may lead to negative impacts on communities dominated by calcifying taxa with planktonic life stages. We exposed Mediterranean mussel (Mytilus galloprovincialis) sperm and early life stages to pHT levels of 8.0 (current pH) and 7.6 (2100 level) by manipulating pCO2 ...
    • Comparison of feature based segmentation of full polarimetric SAR satellite sea ice images with manually drawn ice charts 

      Moen, Mari-Ann; Doulgeris, Anthony Paul; Anfinsen, Stian Normann; Renner, Angelika H.H.; Hughes, Nick; Gerland, Sebastian; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      In this paper we investigate the performance of an algorithm for automatic segmentation of full polarimetric, synthetic aperture radar (SAR) sea ice scenes. The algorithm uses statistical and polarimetric properties of the backscattered radar signals to segment the SAR image into a specified number of classes. This number was determined in advance from visual inspection of the SAR image and by ...
    • Correction and Characterization of Radio Frequency Interference Signatures in L-band Synthetic Aperture Radar Data 

      Meyer, Franz; Nicoll, Jeremy; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Radio frequency interference (RFI) is a known issue in low-frequency radar remote sensing. In synthetic aperture radar (SAR) image processing, RFI can cause severe degradation of image quality, distortion of polarimetric signatures, and an increase of the SAR phase noise level. To address this issue, a processing system was developed that is capable of reliably detecting, characterizing, and mitigating ...
    • Satellittovervåking av isdrift i Arktis 

      Kræmer, Thomas (Conference object; Konferansebidrag, 2013)
    • A Multitexture Model for Multilook Polarimetric Synthetic Aperture Radar Data 

      Eltoft, Torbjørn; Anfinsen, Stian Normann; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      A statistical model for multilook polarimetric radar data is presented where the polarimetric channels are associated with individual texture variables having potentially different statistical properties. The feasibility of producing closed form probability density functions under certain restrictions is outlined. Mellin kind statistics are derived under various assumptions on the texture variables, ...
    • An Advanced Non-Gaussian Feature Space Method for POL-SAR Image Segmentation 

      Doulgeris, Anthony Paul; Eltoft, Torbjørn (Conference object; Konferansebidrag, 2013)
      This work extends upon our simple feature-based multichannel SAR segmentation method to incorporate highly desirable statistical properties into a computationally simple approach. The desirable properties include Markov random field contextual smoothing and goodness-of-fit testing to automatically obtain the significant number of classes. To achieve this we need to find an explicit class model to ...
    • Particle tracking in 3D 

      Brox, Petter (Master thesis; Mastergradsoppgave, 2013-06)
      The evanescent field of an optical waveguide can be used to trap and propel microscopic particles. A 1µm particle is trapped on a strip waveguide and propelled forward until it reaches a 10µm gap at the centre of a loop, created by splitting the waveguide into two branches. According to simulations, the particle will be elevated 3µm in the gap and be stably trapped in the middle of the gap. The goal ...
    • Fluid leakage assessment of the overburden structure at the Sleipner CO2 storage site 

      Lydersen, Ida Bruun (Master thesis; Mastergradsoppgave, 2013-07-13)
      Carbon capture and storage (CCS) has been proposed as one of the alternatives for climate mitigation. CCS is a process where CO2 is trapped from large point sources, transported to a storage location and injected into storage reservoirs. One of the alternatives for CO2-storage is underground geological storage. Characterizing such an underground reservoir is crucial for safe storage, where leakage ...
    • Coastal wind from SAR and NWP model for offshore wind power production 

      Abrahamsen, Malin (Master thesis; Mastergradsoppgave, 2013-07-01)
      With rising energy demands as well as technological advances, offshore wind power production is becoming an attractive option. However, it is necessary to estimate the wind climate at potential sites in order to achieve optimal siting, and numerical weather prediction models as well as satellite SAR can been used in a first evaluation for this purpose. This study looked the how ASAR and model wind ...
    • Comparing SAR measurments of natural oil seeps in the Gulf of Mexico with mineral and biological slicks in the North Sea 

      Hanssen, Claes Anders Storm (Master thesis; Mastergradsoppgave, 2013)
      In this thesis, natural oil seeps in Synthetic Aperture Radar (SAR) images are studied. The intension is to compare seeps to known oil slicks as emulsion-oil, crude-oil and plant-oil. TerraSAR-X and Radarsat-2 data with these di erent slicks are analyzed. Polarimetric features are extracted for all the scenes, histograms and scatterplots of values from the slicks are evaluated. Finally a ...