Now showing items 1061-1080 of 1400

    • X-, C-, and L-band SAR signatures of newly formed sea ice in Arctic leads during winter and spring 

      Johansson, Malin; Brekke, Camilla; Spreen, Gunnar; King, Jennifer A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-02)
      We examine an extensive synthetic aperture radar (SAR) data set from the Arctic Ocean spanning a time period from January to June 2015, with the aim of identifying multi-polarization parameters that can be used to accurately separate newly formed sea ice from the surroundings. Newly formed sea ice areas both provide favourable routing for ship traffic, and are key to Arctic climate science because ...
    • Silicon nitride waveguide platform for fluorescence microscopy of living cells 

      Tinguely, Jean-Claude; Helle, Øystein Ivar; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      Waveguide chip-based microscopy reduces the complexity of total internal reflection fluorescence (TIRF) microscopy, and adds features like large field of view illumination, decoupling of illumination and collection path and easy multimodal imaging. However, for the technique to become widespread there is a need of low-loss and affordable waveguides made of high-refractive index material. Here, ...
    • Solar Wind from Coronal Funnels and Transition Region Lyalpha 

      Esser, Ruth; Lie-Svendsen, Øystein; Janse, Åse Marit; Killie, Mari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2005-08-10)
      Using a newly developed gyrotropic solar wind model that extends continuously from the mid-chromosphere to 1 AU and that accounts for radiative losses in the transition region, we have studied the difference between the fast solar wind emanating from a funnel geometry and a ``traditional'' rapidly expanding wind. The main aim is to determine whether or not observations of the Lyalpha intensity in ...
    • Assessment of RISAT-1 and Radarsat-2 for Sea Ice Observation from Hybrid-Polarity Perspective 

      Espeseth, Martine; Brekke, Camilla; Johansson, Malin (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-25)
      Utilizing several Synthetic Aperture Radar (SAR) missions will provide a data set with higher temporal resolution. It is of great importance to understand the difference between various available sensors and polarization modes and to consider how to homogenize the data sets for a following combined analysis. In this study, a uniform and consistent analysis across different SAR missions is carried ...
    • Marine radar properties, analysis and applications 

      Kaspersen, Kai Magne (Master thesis; Mastergradsoppgave, 2017-08-01)
      In this thesis marine radars are compared with synthetic aperture radars (SAR) and the possibility of cross-over applications are investigated. A first cross-over has been demonstrated by using the TS-CFAR on marine radar images. The TS-CFAR was originally developed for SAR and is a constant false alarm rate (CFAR) detection algorithm based on truncated statistics. Detecting weak targets embedded ...
    • Case study of a large-scale solar, wind and hydro power hybrid system in Skibotndalen, Troms 

      Ingebrigtsen, Karoline (Master thesis; Mastergradsoppgave, 2017-06-06)
      The power company Troms Kraft is interested in the feasibility of a large-scale hybrid system in Skibotndalen in Troms. There are two existing hydro power stations in the area, and this thesis concerns the addition of an electric solar power plant of 20 MW and a wind power plant of 21 MW to these stations. As measured solar radiation is not available for one whole year at the location, solarradiation ...
    • 3-D seismic interpretation of the Samson Dome in the framework of the tectonostratigraphic and fluid migration development of the Western Barents Sea 

      Martiuk, Daria (Master thesis; Mastergradsoppgave, 2017-06-21)
      Three-dimensional (3-D) seismic interpretations of data from the Samson Dome show direct connection between the local geological evolution of the area and the regional tectonic and stratigraphic development of the western Barents Sea. Rifting events, halokinetic movements, uplift and glacial processes influenced the area of the Samson Dome. The Samson Dome structure, located in the south-western ...
    • The link between fluid flow and glacial erosion along the Ringvassøy- Loppa fault complex, Tromsøflaket, SW Barents Sea 

      Berg, June (Master thesis; Mastergradsoppgave, 2017-06-06)
      This master thesis has focused its efforts to investigate the link between glacial erosion and focused fluid flow in the SW Barents Sea, on the shallow bank area of Tromsøflaket where the Ringvassøy-Loppa Fault Complex borders the Tromsø basin in west, and the Loppa High in east. Here, large, elongated depressions are identified on the buried Upper Regional Unconformity (URU) and may resemble tunnel ...
    • Case study of a large-scale solar and wind power hybrid system at Fakken Wind Farm, Troms 

      Tiller, Charlotte (Master thesis; Mastergradsoppgave, 2017-06-01)
      The objective of this thesis is to investigate the feasibility of a large scale hybrid system at Fakken, Troms. There is already an existing 54 MW wind farm at site. The wind farm has considerably higher power production during winter compared to summer, and the electricity grid is therefore not fully exploited during summer. Adding a solar panel utility to the site could be a solution to this issue. ...
    • Changes in paleoceanography and methane release in relation to past climatic variability at Vestnesa Ridge, Svalbard 

      Åsheim, Jarl-Eirik Fløystad (Master thesis; Mastergradsoppgave, 2017-06-01)
      Sediment core HH16-549GC from Vestnesa Ridge in the Fram Strait, western Svalbard, has been investigated in order to reconstruct paleoceanographic and paleoclimatic conditions from 31,000 to 7500 cal years BP. Vestnesa Ridge is located in an area with extensive seepage of methane from the ocean floor. The core is retrieved from within a pockmark to reconstruct possible changes in seepage of methane ...
    • Optimization of wind turbine location in urban environment 

      Hågbo, Trond-Ola (Master thesis; Mastergradsoppgave, 2017-06-01)
      Making energy clean, reliable and readily available is essential for fighting climate change and to supply an ever-rising global power demand. The aim of the study is to identify optimal locations for a wind turbine to be joined to a small-scale hybrid system at the main campus of UiT – The Arctic University of Norway. To identify feasible areas for maximizing electric power production, techniques ...
    • Modelling the future of the arctic sea ice cover 

      Myklebust, Erik Bryhn (Master thesis; Mastergradsoppgave, 2017-06-01)
      Record lows in sea ice cover have recently sparked new interest in the small ice cap instability. The change in albedo when sea ice becomes open water introduces a nonlinearity called the ice-albedo feedback. Forcing a joint energy- balance and sea ice model can lead to unstable ice caps in certain parameter regimes. When the ice caps are unstable, a small perturbation will initiate a tipping point ...
    • Detailed mapping of faults and fractures along Vestnesa ridge 

      Roman, Andrei (Master thesis; Mastergradsoppgave, 2017-05-31)
      This master thesis is focused on studying the Vestnesa Ridge located west of Svalbard. The Vestnesa Ridge is a 100 km long and about 3 km wide sediment drift located on the recently uplifted Svalbard margin. The crest of the ridge is represented with numerous pockmarks with different size, orientation and elongation. High resolution seismic data connected pockmarks with acoustic chimneys and faults ...
    • Modeling probability density functions of non-negative random variables using novel series expansions based on mellin kind statistics 

      Brenn, Torgeir (Master thesis; Mastergradsoppgave, 2017-05-31)
      Mellin kind (MK) statistics is the framework which arises if the Fourier transform is replaced with the Mellin transform when computing the characteristic function from the probability density function. We may then proceed to retrieve logarithmic moments and cumulants, which have important applications in the analysis of heavy-tailed distribution models for non-negative random variables. In this ...
    • Measurements of ionic liquids thermal conductivity and thermal diffusivity 

      Zhao, Yansong; Zhen, Yingpeng; Jelle, Bjørn Petter; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-02)
      Thermal conductivity and thermal diffusivity of ionic liquids (ILs) are investigated in this work. A hot disk method for ILs thermal conductivity and thermal diffusivity measurement is utilized. Firstly, the thermal conductivity of water is measured to check the reliability of the hot disk method. In addition, the thermal conductivity of pure ILs, including BmimBF<sub>4</sub>, BmimPF<sub>6</sub>, ...
    • Unified transport scaling laws for plasma blobs and depletions 

      Wiesenberger, Matthias; Held, Markus; Kube, Ralph; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-14)
      We study the dynamics of seeded plasma blobs and depletions in an (effective) gravitational field. For incompressible flows, the radial center of mass velocity of blobs and depletions is proportional to the square root of their initial cross-field size and amplitude. If the flows are compressible, this scaling holds only for ratios of amplitude to size larger than a critical value. Otherwise, the ...
    • Beam and plasma properties downstream from positively biased source chamber 

      Osnes, Sindre (Master thesis; Mastergradsoppgave, 2017-06-06)
      We study the effect of changing the separation grid bias in a double plasma device from -50 V to the same bias as the anode in the source chamber, 115 V on the plasma and beam parameters downstream in the target chamber. Two different probes were used to analyze the downstream plasma. We used an RFEA-probe to obtain information about the ions, such as the ion energy distribution and we constructed ...
    • First wind shear observation in PMSE with the tristatic EISCAT VHF radar 

      Mann, Ingrid; Häggström, I.; Tjulin, A; Rostami, S; Anyairo, CC; Dalin, P (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-05)
      The Polar Summer Mesosphere has the lowest temperatures that occur in the entire Earth system. Water ice particles below the optically observable size range participate there in the formation of strong radar echoes (Polar Mesospheric Summer Echoes, PMSE). To study PMSE we carried out observations with the European Incoherent Scatter (EISCAT) VHF and EISCAT UHF radar simultaneously from a site near ...
    • Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign 

      Strelnikov, Boris; Szewczyk, Artur; Strelnikova, Irina; Latteck, Ralph; Baumgarten, Gerd; Lübken, Franz-Josef; Rapp, Markus; Fasoulas, Stefanos; Löhle, Stefan; Eberhart, Martin; Hoppe, Ulf-Peter; Dunker, Tim; Friedrich, Martin; Hedin, Jonas; Khaplanov, Mikhail; Gumbel, Jörg; Barjatya, Aroh (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-10)
      In summer 2013 the WADIS-1 sounding rocket campaign was conducted at the Andøya Space Center (ACS) in northern Norway (69 N, 16 E). Among other things, it addressed the question of the variability in mesosphere/lower thermosphere (MLT) turbulence, both in time and space. A unique feature of the WADIS project was multi-point turbulence sounding applying different measurement techniques including ...
    • A Framework for Mellin Kind Series Expansion Methods 

      Brenn, Torgeir; Anfinsen, Stian Normann (Journal article; Tidsskriftartikkel, 2017-07-31)
      Mellin kind statistics (MKS) is the framework which arises if the Fourier transform is replaced with the Mellin transform when computing the characteristic function from the probability density function. We may then proceed to retrieve logarithmic moments and cumulants, that have important applications in the analysis of heavy-tailed distribution models for nonnegative random variables. In this paper ...