Viser treff 2281-2300 av 5336

    • Multi-frequency polarimetric SAR signatures of lead sea ice and oil spills 

      Johansson, Malin; Brekke, Camilla; Spreen, Gunnar (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-04)
      Synthetic aperture radar is used to identify and monitor oil spills. Separation from oil spill look-alikes is an important part of a fully automatic oil spill detection scheme. Here we investigate the polarimetric signatures for oil spills and newly formed sea ice (a well-known look-alike) in fully polarimetric Radarsat-2 satellite scenes. Using the fully polarimetric scenes we calculate four different ...
    • Optical Waveguides for Infrared Spectroscopic Detection of Molecular Gases 

      Vlk, Marek (Doctoral thesis; Doktorgradsavhandling, 2021-06-18)
      Fields like medical diagnostics, urban and industrial environmental monitoring or basic microbiological research greatly benefit from advances in chemical and biological sensing. These applications require rapid sample analysis, reduced needs for sample handling, or good sensor network. Such demands can be met with miniaturised sensors utilising methods which secure sufficient sensitivity and ...
    • Rockfall and snow avalanche impact dynamics for road protection design at Svarthola, Senja. A hazard evaluation aided by numerical models and physical formulas 

      Asplin, Linn (Master thesis; Mastergradsoppgave, 2021-05-14)
      Rockfalls and snow avalanches are a major natural hazard and common phenomenon in mountainous areas in Norway, endangering people and infrastructure. Svarthola, on Fv 862, Senja, is a 100 m long unprotected stretch of road that experiences a high frequency of mass movements. The road is situated at a tunnel portal, between a 100 m high cliff and the fjord. As such, it is the only short access route ...
    • Collapse of a marine-based ice sheet 

      Esteves, Mariana da Silveira Ramos (Doctoral thesis; Doktorgradsavhandling, 2018-08-16)
      The Barents Sea Ice Sheet (BSIS) is a good palaeo-analogue to the West Antarctic Ice Sheet (WAIS), and understanding the key processes occurring during the deglaciation of the BSIS can yield important insights into the drivers and response of marine-based ice sheets to climatic changes. This is important since marine-based ice sheets, such as the BSIS and WAIS, are particularly vulnerable to oceanic ...
    • Organisatorisk resiliens i ambulansetjenesten - En casestudie om hvordan risikostyring kan påvirke organisatorisk resiliens 

      Hunstad, Erlend With (Master thesis; Mastergradsoppgave, 2020-12-06)
      Dagens samfunn stiller store krav til organisasjoner og deres risikohåndtering. Med en økende grad av globalisering i verdenssamfunnet og med større usikkerhet, blir det stadig mer utfordrende å håndtere uønskede hendelser. Risikostyring og organisatorisk resiliens er derfor viktig for en organisasjon å kunne beherske og utvise for å unngå at uønskede hendelser fører til tap av liv, økonomi, materiell, ...
    • Adsorption of Organic Pollutants in Microplastic in the Arctic Ocean 

      Nordang, Unni Mette (Master thesis; Mastergradsoppgave, 2019-05-15)
      Oceans all over the world are housing large quantities of plastic pollution and persistent organic pollutants (POPs). Concerns regarding both of them having lipophilic characteristic that allows a successful partitioning of POPs to plastic if in contact in an aqueous medium, led to this study where the relationship between different types of plastic and POPs in the Arctic ocean are looked into. In ...
    • Reinforcement learning application in diabetes blood glucose control: A systematic review 

      Tejedor Hernandez, Miguel Angel; Woldaregay, Ashenafi Zebene; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-21)
      <p>Background: Reinforcement learning (RL) is a computational approach to understanding and automating goal-directed learning and decision-making. It is designed for problems which include a learning agent interacting with its environment to achieve a goal. For example, blood glucose (BG) control in diabetes mellitus (DM), where the learning agent and its environment are the controller and the body ...
    • Multistatic Specular Meteor Radar Network in Peru: System Description and Initial Results 

      Chau, Jorge L.; Urco, Miguel; Vierinen, Juha; Harding, Brian; Clahsen, Matthias; Pfeffer, Nico; Kuyeng, Karim; Milla, Marco; Erickson, Philip J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)
      The mesosphere and lower thermosphere (MLT) region is dominated globally by dynamics at various scales: planetary waves, tides, gravity waves, and stratified turbulence. The latter two can coexist and be significant at horizontal scales less than 500 km, scales that are difficult to measure. This study presents a recently deployed multistatic specular meteor radar system, SIMONe Peru, which can be ...
    • Chip Based Optical Nanoscopy: System Integration and Automation 

      Hansen, Daniel Henry (Mastergradsoppgave; Master thesis, 2019-05-15)
      An integrated photonic chip based nanoscopy system has previously been developed at UiT, which allows for several advantages over conventional total internal reflection fluorescence microscopy and nanoscopy (i.e. super-resolutionnanoscopy). While the proof-of-concept has been demonstrated, there were several important system optimization tasks that were needed for making the ...
    • Consumer-Based Activity Trackers as a Tool for Physical Activity Monitoring in Epidemiological Studies During the COVID-19 Pandemic: Development and Usability Study 

      Henriksen, André; Johannessen, Erlend; Hartvigsen, Gunnar; Grimsgaard, Sameline; Hopstock, Laila Arnesdatter (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-23)
      Background: Consumer-based physical activity trackers have increased in popularity. The widespread use of these devices and the long-term nature of the recorded data provides a valuable source of physical activity data for epidemiological research. The challenges include the large heterogeneity between activity tracker models in terms of available data types, the accuracy of recorded data, and how ...
    • Environmental impact of sediment-hosted stratiform iron deposits: an on-land vs. submarine tailing simulation. A study of the stratiform iron mineralization in Dunderland Valley. 

      Fagerheim, Birgitte Andrea (Mastergradsoppgave; Master thesis, 2019-05-14)
      This thesis studies possible environmental impacts of tailings from the stratiform iron deposits. The study was conducted on selected mineralized samples from the Dunderland Valley, Nordland, simulating on-land and submarine tailing disposal conditions. The Dunderland Valley mineralization is hosted by Neoproterozoic (Tonian, 800-730 Ma) meta-sedimentary sequence of the Caledonian Uppermost ...
    • Can We Automate Diagrammatic Reasoning? 

      Sekh, Arif Ahmed; Dogra, Debi Prasad; Kar, Samarjit; Roy, Partha Pratim; Prosad, Dilip K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-06)
      Diagrammatic reasoning (DR) problems are well known. However, solving DR problems represented in 4 × 1 Raven’s Progressive Matrix (RPM) form using computer vision and pattern recognition has not yet been tried. Emergence of deep learning techniques aided by advanced computing can be exploited to solve such DR problems. In this paper, we propose a new learning framework by combining LSTM and Convolutional ...
    • Video trajectory analysis using unsupervised clustering and multi-criteria ranking 

      Sekh, Arif Ahmed; Dogra, Debi Prasad; Kar, Samarjit; Roy, Partha Pratim (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-13)
      Surveillance camera usage has increased significantly for visual surveillance. Manual analysis of large video data recorded by cameras may not be feasible on a larger scale. In various applications, deep learning-guided supervised systems are used to track and identify unusual patterns. However, such systems depend on learning which may not be possible. Unsupervised methods relay on suitable features ...
    • Numerical simulations and stochastic modeling of intermittent fluctuations in magnetized plasmas 

      Decristoforo, Gregor (Doctoral thesis; Doktorgradsavhandling, 2021-05-21)
      The exhaust of particles and heat in the boundary of contemporary magnetic confinement experiments remains to this day a major obstacle on the road to commercially viable fusion energy production. It is recognized, that coherent structures of hot and dense plasma, called blobs or filaments, are the dominant mechanism for cross-field particle transport. These filaments are created by plasma turbulence ...
    • Higher weight spectra of codes from Veronese threefolds 

      Johnsen, Trygve; Verdure, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-23)
      We study binary linear codes C obtained from the quadric Veronese embedding of P<sup>3</sup> in P<sup>9</sup> over F<sub>2</sub>. We show how one can find the higher weight spectra of these codes. Our method will be a study of the Stanley-Reisner rings of a series of matroids associated to each code <i>C</i>.
    • Horizontal electric fields from flow of auroral O+(2P) ions at sub-second temporal resolution 

      Tuttle, Sam; Lanchester, Betty; Gustavsson, Björn Johan; Keith Whiter, Daniel; Ivchenko, Nickolay; Fear, R. C.; Lester, Mark (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)
      Electric fields are a ubiquitous feature of the ionosphere and are intimately linked with aurora through particle precipitation and field-aligned currents. They exhibit order-of-magnitude changes on temporal and spatial scales of seconds and kilometres respectively which are not easy to measure; knowing their true magnitude and temporal variability is important for a theoretical understanding of ...
    • Intermittent fluctuations due to Lorentzian pulses in turbulent thermal convection 

      Decristoforo, Gregor; Theodorsen, Audun; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-03)
      Turbulent motions due to flux-driven thermal convection are investigated by numerical simulations and stochastic modeling. Tilting of convection cells leads to the formation of sheared flows and quasi-periodic relaxation oscillations for the energy integrals far from the threshold for linear instability. The probability density function for the temperature and radial velocity fluctuations in the ...
    • Blob interactions in 2D scrape-off layer simulations 

      Decristoforo, Gregor; Militello, Fulvio; Nicholas, Thomas; Omotani, John; Marsden, Chris; Walkden, Nick; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-01)
      Interaction of coherent structures known as blobs in the scrape-off layer of magnetically confined plasmas is investigated. Isolated and interacting seeded blobs, as well as full plasma turbulence, are studied by two-dimensional numerical simulations. The features of the blobs (position, size, amplitude) are determined with a blob tracking algorithm, which identifies them as coherent structures with ...
    • EDMON - Electronic Disease Surveillance and Monitoring Network: A Personalized Health Model-based Digital Infectious Disease Detection Mechanism using Self-Recorded Data from People with Type 1 Diabetes 

      Woldaregay, Ashenafi Zebene (Doctoral thesis; Doktorgradsavhandling, 2021-05-28)
      Through time, we as a society have been tested with infectious disease outbreaks of different magnitude, which often pose major public health challenges. To mitigate the challenges, research endeavors have been focused on early detection mechanisms through identifying potential data sources, mode of data collection and transmission, case and outbreak detection methods. Driven by the ubiquitous nature ...
    • Computational and experimental insights into asymmetric Rh‐catalyzed hydrocarboxylation with CO2 

      Pavlovic, Ljiljana; Pettersen, Martin; Gevorgyan, Ashot; Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-18)
      The asymmetric Rh‐catalyzed hydrocarboxylation of α,β‐unsaturated carbonyl compounds was originally developed by Mikami and co‐workers but gives only moderate enantiomeric excesses. In order to understand the factors controlling the enantioselectivity and to propose novel ligands for this reaction, we have used computational and experimental methods to study the Rh‐catalyzed hydrocarboxylation with ...