Blar i tittel Fakultet for naturvitenskap og teknologi

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    • Laplace transformation of Lie class ω = 1 overdetermined systems 

      Kruglikov, Boris (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-20)
      In this paper, we investigate overdetermined systems of scalar PDEs on the plane with one common characteristic, whose general solution depends on one function of one variable. We describe linearization of such systems and their integration via Laplace transformation, relating this to Lie's integration theorem and formal theory of PDEs.

    • Large amplitude blob propagation in the SOL of Alcator C-Mod and comparison to theoretical model 

      Kube, Ralph; Garcia, Odd Erik; LaBombard, Brian; Terry, James L.; Zweben, Stewart (Conference object; Konferansebidrag, 2012)

    • Large eddy simulation of homogeneous isotropic turbulence 

      Zeigler, Harald Bergersen (Master thesis; Mastergradsoppgave, 2008-06-02)
      The theme for the master thesis is simulation of homogeneous, isotropic turbulence. I have shown that the energy of the velocity field is decaying in time, but the comparison to the reference solution is however invalid, due to the fact that the reference solution may have scalings that are not obvious to the observer, and that my own simulation results seemed to behave quite strange, with a sudden ...

    • Large Multiples : exploring the large-scale scattergun approach to visualization and analysis 

      Holsbø, Einar (Master thesis; Mastergradsoppgave, 2014-05-15)
      We create 2.5 quintillion bytes of data every day. A whole 90% of the world’s data was created in the last two years.1 One contribution to this massive bulk of data is Twitter: Twitter users create 500 million tweets a day,2 which fact has greatly impacted social science [24] and journalism [39]. Network analysis is important in social science [6], but with so much data there is a real danger of ...

    • Large subglacial meltwater features in the central Barents Sea 

      Bjarnadóttir, Lilja Rún; Winsborrow, Monica; Andreassen, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-01)
      During the last glacial period large parts of the Arctic, including the Barents Sea, north of Norway and Russia, were covered by ice sheets. Despite several studies indicating that melting occurred beneath much of the Barents Sea ice sheet, very few meltwater-related landforms have been identified. We document ∼200 seafloor valleys in the central Barents Sea and interpret them to be tunnel valleys ...

    • Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet 

      Hawkings, Jon R.; Linhoff, Benjamin S.; Wadham, Jemma L.; Stibal, Marek; Lamborg, Carl H.; Carling, Gregory T.; Lamarche-Gagnon, Guillaume; Kohler, Tyler J.; Ward, Rachael; Hendry, Katharine R.; Falteisek, Lukáš; Kellerman, Anne M.; Cameron, Karen A.; Hatton, Jade E.; Tingey, Sarah; Holt, Amy D.; Vinšová, Petra; Hofer, Stefan; Bulínová, Marie; Větrovský, Tomáš; Meire, Lorenz; Spencer, Robert G. M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-24)
      The Greenland Ice Sheet is currently not accounted for in Arctic mercury budgets, despite large and increasing annual runoff to the ocean and the socio-economic concerns of high mercury levels in Arctic organisms. Here we present concentrations of mercury in meltwaters from three glacial catchments on the southwestern margin of the Greenland Ice Sheet and evaluate the export of mercury to downstream ...

    • A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude 

      Marschalek, J. W.; Zurli, L.; Talarico, F.; van de Flierdt, T.; Vermeesch, P.; Carter, A.; Beny, F.; Bout-Roumazeilles, V.; Sangiorgi, F.; Hemming, S. R.; Pérez, L. F.; Colleoni, F.; Prebble, J. G.; van Peer, T. E.; Perotti, M.; Shevenell, A. E.; Browne, I.; Kulhanek, D. K.; Levy, R.; Harwood, D.; Sullivan, N. B.; Meyers, S. R.; Griffith, E. M.; Hillenbrand, C. D.; Gasson, E.; Siegert, M. J.; Keisling, B.; Licht, K. J.; Kuhn, G.; Dodd, J. P.; Boshuis, C.; de Santis, L.; McKay, R. M.; Ash, J.; Cortese, G.; Esper, O. V.; Gales, J. A.; Ishino, S.; Kim, Sookwan; Kim, Sunghan; Laberg, Jan Sverre; Leckie, R. M.; Muller, J.; Patterson, M. O.; Romans, B. W.; Romero, O. E.; Seki, O.; Singh, S. M.; Cordeiro de Sousa, I. M.; Sugisaki, S. T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021)
      Early to Middle Miocene sea-level oscillations of approximately 40–60 m estimated from far-field records1,2,3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can ...

    • Large-scale culturing of Neogloboquadrina pachyderma, its growth in, and tolerance of, variable environmental conditions 

      Westgård, Adele; Mohamed, Mohamed Mahmoud Ezat Ahmed; Chalk, Tom; Chierici, Melissa; Foster, Gavin L.; Meilland, Julie (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-09)
      The planktic foraminifera Neogloboquadrina pachyderma is a calcifying marine protist and the dominant planktic foraminifera species in the polar oceans, making it a key species in marine polar ecosystems. The calcium carbonate shells of foraminifera are widely used in palaeoclimate studies because their chemical composition reflects the seawater conditions in which they grow. This species provides ...

    • Large-Scale Detection and Categorization of Oil Spills from SAR Images with Deep Learning 

      Bianchi, Filippo Maria; Espeseth, Martine; Borch, Njål Trygve (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)
      We propose a deep-learning framework to detect and categorize oil spills in synthetic aperture radar (SAR) images at a large scale. Through a carefully designed neural network model for image segmentation trained on an extensive dataset, we obtain state-of-the-art performance in oil spill detection, achieving results that are comparable to results produced by human operators. We also introduce a ...

    • Large-Scale Mapping of Small Roads in Lidar Images Using Deep Convolutional Neural Networks 

      Salberg, Arnt Børre; Trier, Øivind Due; Kampffmeyer, Michael C. (Chapter; Bokkapittel, 2017-05-19)
      Detailed and complete mapping of forest roads is important for the forest industry since they are used for timber transport by trucks with long trailers. This paper proposes a new automatic method for large-scale mapping forest roads from airborne laser scanning data. The method is based on a fully convolutional neural network that performs end-to-end segmentation. To train the network, a large set ...

    • Laser Based Altimetry for Unmanned Aerial Vehicle Hovering Over a Snow Surface 

      Haugen, Hallvard (Master thesis; Mastergradsoppgave, 2017-06-02)
      A microwave radar for non-invasive snow stratigraphy measurements has been developed. Results were promising, but it failed to detect light powder snow in the air-snowpack interface. The aim of this thesis is to find and verify a system for estimating altitude on centimeter scale over a snow surface, independent of snow conditions. Also, relative pitch and roll angle estimation between the UAV and ...

    • Laser diagnostics of the mesospheric magnetic field. Understanding remote laser magnetometry in northern Norway 

      Serrano, Alessandra (Master thesis; Mastergradsoppgave, 2017-05-15)
      This thesis outlines initial motivations and propositions for the Mesospheric Optical Magnetometry (MOM) project, using lidar equipment at ALOMAR observatory in northern Norway to initiate a novel technique for measuring Earth’s magnetic field at approximately 90 km altitude. Included is an in-depth discussion of the physical phenomena within Earth’s mesospheric sodium layer, relevant atomic physics, ...

    • Laser-Generated Scholte Waves in Floating Microparticles 

      Ranjan, Abhishek; Ahmad, Azeem; Ahluwalia, Balpreet Singh; Melandsø, Frank (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-04)
      This study aims to demonstrate the generation and detection of Scholte waves inside polystyrene microparticles. This was proven using both experimental analysis and COMSOL simulation. Microspheres of different sizes were excited optically with a pulsed laser (532 nm), and the acoustic signals were detected using a transducer (40 MHz). On analyzing the laser-generated ultrasound signals, the results ...

    • The last 2 Myr of accretionary wedge construction in the central Hikurangi margin (North Island, New Zealand): Insights from structural modeling 

      Ghisetti, Francesca C.; Barnes, Philip M.; Ellis, Susan; Plaza-Faverola, Andreia; Barker, Daniel H.N. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-17)
      Three depth-converted and geologically interpreted seismic profiles provide a clear image of the offshore outer accretionary wedge associated with oblique subduction of the Pacific Plate beneath the central Hikurangi margin. Plio-Quaternary turbidites deposited over the pelagic cover sequence of the Hikurangi Plateau have been accreted to the margin by imbrication along E-verging thrust faults that ...

    • Last glacial ice sheet dynamics offshore NE Greenland – a case study from Store Koldewey Trough 

      Olsen, Ingrid Leirvik; Rydningen, Tom Arne; Forwick, Matthias; Laberg, Jan Sverre; Husum, Katrine (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-04)
      The presence of a grounded Greenland Ice Sheet on the northeastern part of the Greenland continental shelf during the Last Glacial Maximum is supported by new swath bathymetry and high-resolution seismic data, supplemented with multi-proxy analyses of sediment gravity cores from Store Koldewey Trough. Subglacial till fills the trough, with an overlying drape of maximum 2.5 m thick glacier-proximal ...

    • Last Glacial Maximum – Holocene palaeoenvironment in Bessel Fjord and southwestern Dove Bugt, Northeast Greenland 

      Zoller, Kevin Michael (Master thesis; Mastergradsoppgave, 2020-05-14)
      Marine studies reconstructing ice sheet conditions on the Northeast Greenland shelf and adjacent fjords since the Last Glacial Maximum (LGM) are sparse. As a result, the timing and origin of the deglaciation of the ice sheet over marine areas is not well constrained. This thesis aims to improve our understanding of the LGM, deglaciation, and Holocene ice dynamics of the Greenland Ice Sheet (GrIS) ...

    • The last hop of global notification delivery to mobile users. Matching preferences, context, and device constraints. 

      Zagorodnov, Dmitrii; Johansen, Dag (Research report; Forskningsrapport, 2004)
      Events injected by publishers into a publish/subscribe system may reach users through a variety of devices: a stationary desktop, a laptop, a mobile phone, etc. We argue that the "last hop" -- from the network to the output device -- has unique properties, owing to the mobile nature of these devices, and as such demands special consideration. In particular, user's preferences and location may limit ...

    • The last two millennia: climate, ocean circulation and paleoproductivity inferred from planktic foraminifera, south-western Svalbard margin 

      Zamelczyk, Katarzyna; Rasmussen, Tine Lander; Raitzsch, Markus; Chierici, Melissa (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-20)
      We reconstruct climate and changes in water-mass properties in relation to variations in palaeoproductivity at the south-western Svalbard margin throughout the last 2000 years. Environmental conditions in subsurface (ca. 250–75 m) and near-surface to surface water (75–0 m) were studied on the basis of the distribution patterns and fluxes of planktic foraminiferal faunas. Stable isotopes in three ...

    • Late Cenozoic development of the continental margin off Lofoten-Vesterålen and Troms 

      Rydningen, Tom Arne; Vorren, Tore Ola (Conference object; Konferansebidrag, 2011)

    • Late Cenozoic development of the mid-Norwegian continental margin – a study of the Naust Formation based on 3D-seismic data 

      Lundegaard, Marius (Master thesis; Mastergradsoppgave, 2020-06-15)
      The late Cenozoic evolution of the outer continental shelf and slope on the northern part of the mid-Norwegian margin is studied using 3D seismic data. The late Cenozoic stratigraphy is subdivided into four main seismic units: unit A (oldest) to D and correlated to the established stratigraphic framework of the Naust Formation, where the oldest unit in this study correlates to the upper part of Naust ...