Viser treff 521-540 av 1276

    • Incident Angle Dependence of Sentinel-1 Texture Features for Sea Ice Classification 

      Lohse, Johannes; Doulgeris, Anthony Paul; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-04)
      Robust and reliable classification of sea ice types in synthetic aperture radar (SAR) images is needed for various operational and environmental applications. Previous studies have investigated the class-dependent decrease in SAR backscatter intensity with incident angle (IA); others have shown the potential of textural information to improve automated image classification. In this work, we investigate ...
    • Wind at Northern Senja: Use of numerical weather prediction models for wind resource assessment 

      Hansen, Gjøran Emil (Master thesis; Mastergradsoppgave, 2020-12-15)
      Wind resource assessment for establishing decentralized power production in remote and complex areas, is challenging due to a lack of observational data. To overcome this problem, Numerical Weather Prediction (NWP) models can be used to provide data where no observations exist. This thesis uses NWP models to do a wind resource assessment at northern Senja. The power grid in the area is prone to ...
    • CO2 Increase Experiments Using the CESM: Relationship to Climate Sensitivity and Comparison of CESM1 to CESM2 

      Bacmeister, Julio T.; Hannay, Cecile; Medeiros, Brian; Gettelmann, Andrew; Neale, Richard; Fredriksen, Hege-Beate; Lipscomb, William H.; Simpson, Isla; Bailey, David Anthony; Holland, Marika M.; Lindsay, Keith; Otto-Bliesner, Bette L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-14)
      We examine the response of the Community Earth System Model Versions 1 and 2 (CESM1 and CESM2) to abrupt quadrupling of atmospheric CO2 concentrations (4xCO2) and to 1% annually increasing CO2 concentrations (1%CO2). Different estimates of equilibrium climate sensitivity (ECS) for CESM1 and CESM2 are presented. All estimates show that the sensitivity of CESM2 has increased by 1.5 K or more over that ...
    • Klimanøytral miljøpark – en vurdering av kostnader og nytteverdi for klimagassreduserende tiltak 

      Strand, Petter Hofstad (Master thesis; Mastergradsoppgave, 2020-12-14)
      Remiks AS har gjennom flere år gjort en kartlegging av klimagassutslipp knyttet til egen virksomhet. På bakgrunn av dette er det iverksatt flere tiltak på aktuelle områder som har blitt identifisert. Det er i midlertidig ikke sikkert at investeringene som er gjort er de mest effektive tiltakene om man vurderer kostnadene mot klimanytten. Denne studien vil vurdere tiltakene solenergi, biodrivstoff, ...
    • Wideband Self-Interference Cancellation Using Multi-Tap Filter in Radar Front End 

      Heiskel, Bendik (Mastergradsoppgave; Master thesis, 2020-12-14)
      The largest hurdle in full duplex wireless systems is the self-interference introduced by the transmitted signal into the received signal. In multi antenna systems this interference is caused by the direct coupling between the transmitting and receiving antennas. In systems where the transmitter and receiver uses the same antenna the interference is caused by inadequate isolation between the ...
    • Performance and Future Potential of Solar Photovoltaics in Arctic Settlements 

      Mathiesen, Vemund Nygaard (Master thesis; Mastergradsoppgave, 2020-12-15)
      Data from a solar photovoltaic (PV) installation on Svalbard Airport Longyear has been analyzed to investigate performance of solar photovoltaics in the Arctic. Results show that the average capacity factor at the facility is 5.6 % after its first two full years of production. While the production in the winter is zero, monthly capacity factors are observed to be as high as 16 % in the summer. On ...
    • Silicon substrate significantly alters dipole-dipole resolution in coherent microscope 

      Liu, Zicheng; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-16)
      Considering a coherent microscopy setup, influences of the substrate below the sample in the imaging performances are studied, with a focus on high refractive index substrate such as silicon. Analytical expression of 3D full-wave vectorial point spread function, i.e. the dyadic Green's function is derived for the optical setup together with the substrate. Numerical analysis are performed in order ...
    • Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples 

      Butola, Ankit; Prasad, Dilip Kumar; Ahmad, Azeem; Dubey, Vishesh Kumar; Qaiser, Darakhshan; Srivastava, Anurag; Senthilkumaran, Paramasivam; Ahluwalia, Balpreet Singh; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-13)
      Optical coherence tomography (OCT) is being increasingly adopted as a label-free and non-invasive technique for biomedical applications such as cancer and ocular disease diagnosis. Diagnostic information for these tissues is manifest in textural and geometric features of the OCT images, which are used by human expertise to interpret and triage. However, it suffers delays due to the long process of ...
    • Properties and dynamics of mesoscale eddies in Fram Strait from a comparison between two high-resolution ocean-sea ice models 

      Wekerle, Claudia; Hattermann, Tore; Wang, Qiang; Crews, Laura; von Appen, Wilken-Jon; Danilov, Sergey (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-23)
      Fram Strait, the deepest gateway to the Arctic Ocean, is strongly influenced by eddy dynamics. Here we analyse the output from two eddy-resolving models (ROMS – Regional Ocean Modeling System; FESOM – Finite-Element Sea-ice Ocean Model) with around 1 km mesh resolution in Fram Strait, with a focus on their representation of eddy properties and dynamics. A comparison with mooring observations shows ...
    • Integrated analysis of multi-sensor datasets and oil drift simulations - a free floating oil experiment in the open ocean 

      Brekke, Camilla; Espeseth, Martine; Dagestad, Knut-Frode; Röhrs, Johannes; Hole, Lars Robert; Reigber, Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-20)
      A free‐floating oil spill experiment (two oil types) in the open ocean is described, and the results from slick characterization through integrated analysis of drift simulations with remote sensing and in situ data are discussed. We compare oil drift simulations (OpenOil), applying various configurations of wind, wave, and current information, with the observed slick positions and shape. We describe ...
    • Artefact removal in ground truth deficient fluctuations-based nanoscopy images using deep learning 

      Jadhav, Suyog; Acuña Maldonado, Sebastian Andres; Opstad, Ida Sundvor; Ahluwalia, Balpreet Singh; Agarwal, Krishna; Prasad, Dilip K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-08)
      Image denoising or artefact removal using deep learning is possible in the availability of supervised training dataset acquired in real experiments or synthesized using known noise models. Neither of the conditions can be fulfilled for nanoscopy (super-resolution optical microscopy) images that are generated from microscopy videos through statistical analysis techniques. Due to several physical ...
    • Machine learning derived input-function in a dynamic 18F-FDG PET study of mice 

      Kuttner, Samuel; Wickstrøm, Kristoffer Knutsen; Kalda, Gustav; Dorraji, Seyed Esmaeil; Martin-Armas, Montserrat; Oteiza, Ana; Jenssen, Robert; Fenton, Kristin Andreassen; Sundset, Rune; Axelsson, Jan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)
      Tracer kinetic modelling, based on dynamic <sup>18</sup>F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is used to quantify glucose metabolism in humans and animals. Knowledge of the arterial input-function (AIF) is required for such measurements. Our aim was to explore two non-invasive machine learning-based models, for AIF prediction in a small-animal dynamic FDG PET study. 7 tissue ...
    • Photonic-chip based free space beam shaping and steering for advanced optical microscopy application 

      Lahrberg, Marcel; Dullo, Firehun Tsige; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-12)
      Photonic-chip-based light illumination has recently found applications in optical microscopy and nanoscopy methodologies. The photonic chip removes the dependency on imaging objective lenses to generate the required illumination patterns for different microscopy methods. Until now, all the reported chip-based optical microscopy methods exploit the evanescent field present on top of a waveguide surface ...
    • Drone-Mounted UWB Snow Radar: Technical Improvements and Field Results 

      Jenssen, Rolf-Ole Rydeng; Jacobsen, Svein Ketil (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-04)
      Drone borne radar systems have seen considerable advances over recent years, and the application of drone-mounted continuous wave (CW) radars for remote sensing of snow properties has great potential. Regardless, major challenges remain in antenna design for which both low weight and small size combined with high gain and bandwidth are important design parameters. Additional limiting factors for CW ...
    • Soft thresholding schemes for multiple signal classification algorithm 

      Acuña Maldonado, Sebastian Andres; Opstad, Ida Sundvor; Godtliebsen, Fred; Ahluwalia, Balpreet Singh; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-28)
      Multiple signal classification algorithm (MUSICAL) exploits temporal fluctuations in fluorescence intensity to perform super-resolution microscopy by computing the value of a super-resolving indicator function across a fine sample grid. A key step in the algorithm is the separation of the measurements into signal and noise subspaces, based on a single user-specified parameter called the threshold. ...
    • Learning Nanoscale Motion Patterns of Vesicles in Living Cells 

      Sekh, Arif Ahmed; Opstad, Ida Sundvor; Birgisdottir, Åsa B.; Myrmel, Truls; Ahluwalia, Balpreet Singh; Agarwal, Krishna; Prasad, Dilip K. (Conference object; Konferansebidrag, 2020-08-05)
      Detecting and analyzing nanoscale motion patterns of vesicles, smaller than the microscope resolution (~250 nm), inside living biological cells is a challenging problem. State-of-the-art CV approaches based on detection, tracking, optical flow or deep learning perform poorly for this problem. We propose an integrative approach, built upon physics based simulations, nanoscopy algorithms, and shallow ...
    • Oil-Spill-Response-Oriented Information Products Derived From a Rapid-Repeat Time Series of SAR Images 

      Espeseth, Martine; Jones, Cathleen; Benjamin, Holt; Brekke, Camilla; Skrunes, Stine (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)
      New quantitative and semiautomated methods for analyzing oil slick evolution using a time series of L-band synthetic aperture radar (SAR) images with short repeat time are developed and explored. In this study, two methods that are complementary in terms of identifying temporal changes within an oil slick are presented. The two methods reflect two ways of evaluating the oil slicks. The first method ...
    • Predicting the suitability of lateritic soil type for low cost sustainable housing with image recognition and machine learning techniques 

      Olukan, Tuza Adeyemi; Chiou, Yu-Cheng; Chiu, Cheng-Hsiang; Lai, Chia-Yun; Santos Hernandez, Sergio; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-10)
      From a sustainability point of view, laterites-compressed earth bricks (LCEB) are a promising substitute for building structures in place of the conventional concrete masonry units. On the other hand, techniques for identifying and classifying laterites soil for compressed earth bricks (CEB) production are still relying on direct human expertise or ‘experts’. Human experts exploit direct visual ...
    • Robustness of SAR Sea Ice Type classification across incidence angles and seasons at L-band 

      Singha, Suman; Johansson, Malin; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel, 2020-11-16)
      In recent years, space-borne synthetic aperture radar (SAR) polarimetry has become a valuable tool for sea ice type retrieval. L-band SAR has proven to be sensitive toward deformed sea ice and is complementary compared with operationally used C-band SAR for sea ice type classification during the early and advanced melt seasons. Here, we employ an artificial neural network (ANN)-based sea ice type ...
    • Comparing wavelet and Fourier perspectives on the decomposition of meridional energy transport into synoptic and planetary components 

      Heiskanen, Tuomas Ilkka Henrikki; Graversen, Rune Grand; Rydsaa, Johanne Hope; Isachsen, Pål Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-04)
      The Arctic region shows some of the world's most significant signs of climate change; for instance, a negative trend in summer sea‐ice cover of around 15% per decade and Arctic amplified surface‐air warming that is three times the global average. The atmospheric energy transport plays an important role in the Arctic climate. Recently a Fourier‐based method for studying the atmospheric energy transport ...