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    • Nanoscopy of bacterial cells immobilized by holographic optical tweezers 

      Diekmann, Robin; Wolfson, Deanna; Spahn, Christoph; Heilemann, Mike; Schuttpelz, Mark; Huser, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-13)
      Imaging non-adherent cells by super-resolution far-field fluorescence microscopy is currently not possible because of their rapid movement while in suspension. Holographic optical tweezers (HOTs) enable the ability to freely control the number and position of optical traps, thus facilitating the unrestricted manipulation of cells in a volume around the focal plane. Here we show that immobilizing ...
    • Oil spill characterization in the hybrid-polarity SAR domain using log-cumulants 

      Espeseth, Martine; Skrunes, Stine; Brekke, Camilla; Salberg, Arnt Børre; Jones, Cathleen; Holt, Benjamin (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-10-18)
      Log-cumulants have proven to be an interesting tool for evaluating the statistical properties of potential oil spills in polarimetric Synthetic Aperture Radar (SAR) data within the common horizontal (H) and vertical (V) polarization basis. The use of first, second, and third order sample log-cumulants has shown potential for evaluating the texture and the statistical distributions, as well as ...
    • A Segmentation based CFAR detection algorithm using truncated statistics 

      Ding, Tao; Doulgeris, Anthony Paul; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-18)
      Target detection in nonhomogeneous sea clutter environments is a complex and challenging task due to the capture effect from interfering outliers and the clutter edge effect from background intensity transitions. For synthetic aperture radar (SAR) measurements, those issues are commonly caused by multiple targets and meteorological and oceanographic phenomena, respectively. This paper proposes a ...
    • A Multisensor Comparison of Experimental Oil Spills in Polarimetric SAR for High Wind Conditions 

      Skrunes, Stine; Brekke, Camilla; Jones, Cathleen Elaine; Holt, Benjamin (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-06-23)
      In this paper, we present the experimental setup and data collection during the Norwegian Radar oil Spill Experiment 2015, followed by a comparison of a subset of the multisensory synthetic aperture radar (SAR) imagery collected during the experiment. Multipolarization SAR data acquired by Radarsat-2, TerraSAR-X, and the uninhabited aerial vehicle synthetic aperture radar (UAVSAR) less than 6 min ...
    • Characterization and discrimination of evolving mineral and plant oil slicks based on L-band synthetic aperture radar (SAR) 

      Jones, Cathleen; Espeseth, Martine Mostervik; Holt, Benjamin; Brekke, Camilla; Skrunes, Stine (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-10-18)
      Evolution of the damping ratio for Bragg wavenumbers in the range 32-43 rad/m is evaluated for oil slicks of different composition released in the open ocean and allowed to develop naturally. The study uses quad-polarimetric L-band airborne synthetic aperture radar data acquired over three mineral oil emulsion releases of different, known oil-to-water ratio, and a near-coincident release of 2-ethylhexyl ...
    • Level crossings, excess times, and transient plasma-wall interactions in fusion plasmas 

      Theodorsen, Audun; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-19)
      Based on a stochastic model for intermittent fluctuations in the boundary region of magnetically confined plasmas, an expression for the level crossing rate is derived from the joint distribution of the process and its derivative. From this the average time spent by the process above a certain threshold level is obtained. This provides novel predictions of plasma–wall interactions due to transient ...
    • Dynamics of the Terra Nova Bay Polynya: The potential of multi-sensor satellite observations 

      Hollands, Thomas; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-10-10)
      Research on processes leading to formation, maintenance, and disappearance of polynyas in the Polar Regions benefits significantly from the use of different types of remote sensing data. The Sentinels of the European Space Agency (ESA), together with other satellite missions, provide a variety of data from different parts of the electromagnetic spectrum, at different spatial scales, and with ...
    • On the improvement and acceleration of eigenvalue decomposition in spectral methods using GPUs 

      Johansen, Thomas A. Haugland (Master thesis; Mastergradsoppgave, 2016-12-08)
      The key objectives in this thesis are; the study of GPU-accelerated eigenvalue decomposition in an effort to uncover both benefits and pitfalls, and then to investigate and facilitate a future GPU implementation of the symmetric QR algorithm with permutations. With the current trend of having ever larger datasets both in terms of features and observations, we propose that GPU computation can help ...
    • Scrape-off layer turbulence in TCV: Evidence in support of stochastic modelling. 

      Theodorsen, Audun; Garcia, Odd Erik; Horacek, Jan; Kube, Ralph; Pitts, RA (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-28)
      Intermittent fluctuations in the TCV scrape-off layer have been investigated by analysing long Langmuir probe data time series under stationary conditions, allowing calculation of fluctuation statistics with high accuracy. The ion saturation current signal is dominated by the frequent occurrence of large-amplitude bursts attributed to filament structures moving through the scrape-off layer. The ...
    • Stochastic modelling of intermittent fluctuations in the scrape-off layer: Correlations, distributions, level crossings, and moment estimation 

      Garcia, Odd Erik; Kube, Ralph; Theodorsen, Audun; Pecseli, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05)
      A stochastic model is presented for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas. The fluctuations in the plasma density are modeled by a super-position of uncorrelated pulses with fixed shape and duration, describing radial motion of blob-like structures. In the case of an exponential pulse shape and exponentially distributed pulse amplitudes, predictions are ...
    • Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone 

      Edvardsen, Inge; Johnsen, Magnar Gullikstad; Løvhaug, Unni Pia (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-02)
      The geomagnetic field often experiences large fluctuations, especially at high latitudes in the auroral zones. We have found, using simulations, that there are significant differences in the substorm signature, in certain coordinate systems, as a function of longitude. This is confirmed by the analysis of real, measured data from comparable locations. Large geomagnetic fluctuations pose ...
    • Delt situasjonsforståelse under søk og redning i nordområdene 

      Haugstveit, Ida Maria; Skjetne, Jan Håvard; Walderhaug, Ståle; Antonsen, yngve; Ellingsen, May-Britt; Håheim-Saers, Nils; Heggelund, Yngve; Anfinsen, Stian Normann (Research report; Forskningsrapport, 2016-05-03)
      Prosjektets mål er å bidra til økt kunnskap om hvordan etablere delt situasjonsforståelse mellom sentrale aktører innen SAR i Nordområdet. Prosjektgruppa har arbeidet ut ifra en menneske-teknologi-organisasjon (MTO) tilnærming og hvor vi har sett på <br>1) menneskelige og organisatoriske faktorer og <br>2) tekniske faktorer som virker inn på etableringen av delt situasjonsforståelse mellom aktører.<br> ...
    • A Brief Look at the Performance of PV in Norway 

      Haumann, Tobias (Master thesis; Mastergradsoppgave, 2016-12-15)
      In the past years the Norwegian PV market has grown substantially. The importance of data on how PV systems perform in Norway is therefore also increasing. In this thesis several Norwegian PV systems are analyzed mainly in terms of annual specific yields. The systems are located in western and southeastern Norway and near horizontal, tilted and vertical modules are looked at. Results show pretty ...
    • Scanning acoustic microscopy—A novel noninvasive method to determine tumor interstitial fluid pressure in a xenograft tumor model 

      Hofmann, Matthias; Pflanzer, Ralph; Habib, Anowarul; Shelke, Amit; Bereiter-Hahn, Jürgen; Bernd, August; Kaufmann, Roland; Sader, Robert; Kippenberger, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-22)
      Elevated tumor interstitial fluid pressure (TIFP) is a prominent feature of solid tumors and hampers the transmigration of therapeutic macromolecules, for example, large monoclonal antibodies, from tumor-supplying vessels into the tumor interstitium. TIFP values of up to 40 mm Hg have been measured in experimental solid tumors using two conventional invasive techniques: the wick-in-needle and the ...
    • Amplitude and size scaling for interchange motions of plasma filaments 

      Kube, Ralph; Wiesenberger, Matthias; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-07)
      The interchange dynamics and velocity scaling of blob-like plasma filaments are investigated using a two-field reduced fluid model. For incompressible flows due to buoyancy, the maximum velocity is proportional to the square root of the relative amplitude and the square root of its cross-field size. For compressible flows in a non-uniform magnetic field, this square root scaling only holds ...
    • Wind speed and direction predictions by WRF and WindSim coupling over Nygårdsfjell 

      Bilal, Muhammad; Birkelund, Yngve; Solbakken, Kine (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      In this study, the performance of the mesoscale meteorological Weather Research and Forecast (WRF) model coupled with the microscale computational fluid dynamics based model WindSim is investigated and compared to the performance of WRF alone. The two model set-ups, WRF and WRF-WindSim, have been tested on three high-wind events in February, June and October, over a complex terrain at the ...
    • Interpreting sea surface slicks on the basis of the normalized radar cross-section model using RADARSAT-2 copolarization dual-channel SAR images 

      Dmitry V., Ivonin; Skrunes, Stine; Brekke, Camilla; Ivanov, A. Yu. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-24)
      A simple automatic multipolarization technique for discrimination of main types of thin oil films (of thickness less than the radio wave skin depth) from natural ones is proposed. It is based on a new multipolarization parameter related to the ratio between the damping in the slick of specially normalized resonant and nonresonant signals calculated using the normalized radar cross-section model ...
    • Wind resource assessment using mesoscale modelling. A case study at the potential wind farm site Rieppi 

      Blæsterdalen, Torgeir (Master thesis; Mastergradsoppgave, 2016-06-01)
      The growing wind power industry, increased occurrence of extreme weather, and the need for becoming independent of fossil fuels motivate the research on accurate simulation of near-surface wind. The aim of this study is wind resource assessment at the potential wind park site Rieppi, using two on-site measurement masts, simulations from the Weather Research and Forecasting (WRF) model, and ERA-Interim ...
    • Numerical computations of turbulent motions in magnetized plasmas 

      Decristoforo, Gregor (Master thesis; Mastergradsoppgave, 2016-05-18)
      Intermittent fluctuations and turbulence-induced transport of magnetically confined fusion plasmas are investigated by numerical computations. A reduced fluid model describing the evolution of plasma pressure and electric drift vorticity in a two-dimensional plane perpendicular to the magnetic field is derived. A numerical simulation code implemented on graphical processing units is presented. We ...
    • Sensitivity to pressure and methane of a cryptophane-A doped polymer 

      Ingvaldsen, Martin (Master thesis; Mastergradsoppgave, 2015-12-15)
      The principle focus of this thesis is the characterization of an on-chip methane sensor based on a waveguide interferometer. It incorporates cryptophane-A molecules in the waveguide cladding to enhance sensitivity and selectivity towards methane. First, the sensor was characterized for sensitivities to ambient conditions, in particular its temperature and pressure sensitivity. The measurement ...