Blar i tittel Artikler, rapporter og annet (fysikk og teknologi)

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    • Magnetotelluric signatures of the complex tertiary fold–thrust belt and extensional fault architecture beneath Brøggerhalvøya, Svalbard 

      Beka, Thomas Ibsa; Bergh, Steffen G; Smirnov, Maxim; Birkelund, Yngve (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-18)
      Magnetotelluric (MT) data were recently collected on Brøggerhalvøya, Svalbard, in a 0.003–1000 s period range along a curved WNW–ESE profile. The collected data manifested strong three-dimensional (3D) effects. We modelled the full impedance tensor with tipper and bathymetry included in 3D, and benchmarked the result with determinant data two-dimensional (2D) inversion. The final inversion results ...

    • Magnitude of extreme heat waves in present climate and their projection in a warming world 

      Russo, S.; Dosio, A.; Graversen, Rune; Sillmann, Jana; Carrao, H.; Dunbar, M.B.; Singleton, Andrew B.; Montagna, P.; Barbosa, P.; Vogt, Jürgen V. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      An extreme heat wave occurred in Russia in the summer of 2010. It had serious impacts on humans and natural ecosystems, it was the strongest recorded globally in recent decades and exceeded in amplitude and spatial extent the previous hottest European summer in 2003. Earlier studies have not succeeded in comparing the magnitude of heat waves across continents and in time. This study introduces a new ...

    • Malin letar oljespill i ishavet 

      Johansson, Malin; Liljebäck, Lars-Erik (Chronicle; Kronikk, 2020-03-13)

    • Manx Arrays: Perfect Non-Redundant Interferometric Geometries 

      McKay, Derek; Grydeland, Tom; Gustavsson, Bjorn Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-09)
      Interferometry applications (e.g., radio astronomy) often wish to optimize the placement of the interferometric elements. One such optimal criterion is a uniform distribution of non-redundant element spacings (in both distance and position angle). While large systems, with many elements, can rely on saturating the sample space, and disregard “wasted” sampling, small arrays with only a few elements ...

    • Mapping sea-ice types from Sentinel-1 considering the surface-type dependent effect of incidence angle 

      Lohse, Johannes; Doulgeris, Anthony Paul; Dierking, Wolfgang (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-23)
      Automated classification of sea-ice types in Synthetic Aperture Radar (SAR) imagery is complicated by the class-dependent decrease of backscatter intensity with Incidence Angle (IA). In the log-domain, this decrease is approximately linear over the typical range of space-borne SAR instruments. A global correction does not consider that different surface types show different rates of decrease in ...

    • Mapping the extent of giant Antarctic icebergs with deep learning 

      Braakmann-Folgmann, Anne Christina; Shepherd, Andrew; Hogg, David; Redmond, Ella (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-09)
      Icebergs release cold, fresh meltwater and terrigenous nutrients as they drift and melt, influencing the local ocean properties, encouraging sea ice formation and biological production. To locate and quantify the fresh water flux from Antarctic icebergs, changes in their area and thickness have to be monitored along their trajectories. While the locations of large icebergs are operationally tracked ...

    • Maximizing Interpretability and Cost-Effectiveness of Surgical Site Infection (SSI) Predictive Models Using Feature-Specific Regularized Logistic Regression on Preoperative Temporal Data 

      Kocbek, Primoz; Fijacko, Nino; Soguero-Ruiz, Cristina; Mikalsen, Karl Øyvind; Maver, Uros; Brzan, Petra Povalej; Stozer, Andraz; Jenssen, Robert; Skrøvseth, Stein Olav; Stiglic, Gregor (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-19)
      This study describes a novel approach to solve the surgical site infection (SSI) classification problem. Feature engineering has traditionally been one of the most important steps in solving complex classification problems, especially in cases with temporal data. The described novel approach is based on abstraction of temporal data recorded in three temporal windows. Maximum likelihood L1-norm ...

    • Measurement of inner wall limiter SOL widths in KSTAR tokamak 

      Bak, J. G.; Pitts, RA; Kim, HS; Lee, H; Bin, C.; Juhn, JW; Hong, SH; Garcia, Odd Erik; Kube, Ralph Arthur; Seo, DC (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-27)
      Scrape-off layer (SOL) widths <i>λ<sub>q</sub></i> are presented from the KSTAR tokamak using fast reciprocating Langmuir probe assembly (FRLPA) measurements at the outboard mid-plane (OMP) and the infra-Red (IR) thermography at inboard limiter tiles in moderately elongated (<i>κ</i> = 1.45 – 1.55) L-mode inner wall-limited (IWL) plasmas under experimental conditions such as B<sub>T</sub> = 2.0 T, ...

    • Measurement of Oil Slick Transport and Evolution in the Gulf of Mexico using L-band Synthetic Aperture Radar 

      Jones, Cathleen; Espeseth, Martine; Holt, Benjamin; Brekke, Camilla (Journal article; Tidsskriftartikkel, 2018-06)
      The transport and evolution of a mineral oil slick originating at a seep in the Gulf of Mexico approximately 16 km offshore of the mouth of the Mississippi River is measured using a series of images acquired at 40 minute intervals with the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), an L-band, high resolution, high signal-to-noise instrument operated by the U.S. National Aeronautics ...

    • Measurement of snow water equivalent using drone-mounted ultra-wide-band radar 

      Jenssen, Rolf Ole R.; Jacobsen, Svein Ketil (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-02)
      The use of unmanned aerial vehicle (UAV)-mounted radar for obtaining snowpack parameters has seen considerable advances over recent years. However, a robust method of snow density estimation still needs further development. The objective of this work is to develop a method to reliably and remotely estimate snow water equivalent (SWE) using UAV-mounted radar and to perform initial field experiments. ...

    • 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>, ...

    • Measuring Wind Speed Using the Internal Stabilization System of a Quadrotor Drone 

      Simma, Magdalena; Mjøen, Håvard; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-16)
      This article proposes a method of measuring wind speed using the data logged by the autopilot of a quadrotor drone. Theoretical equations from works on quadrotor control are utilized and supplemented to form the theoretical framework. Static thrust tests provide the necessary parameters for calculating wind estimates. Flight tests were conducted at a test site with laminar wind conditions with the ...

    • Mesopause dynamics from the scandinavian triangle of radars within the PSMOS-DATAR Project. 

      Hall, Chris; Manson, A.H.; Meek, C.E.; Nozawa, S.; Mitchell, N.J.; Pancheva, D.; Singer, W.; Hoffmann, P. (Journal article; Peer reviewed; Tidsskriftartikkel, 2004-01-01)
      The "Scandinavian Triangle" is a unique trio of radars within the DATAR Project (Dynamics and Temperatures from the Arctic MLT (60–97km) region): Andenes MF radar (69°N, 16°E); Tromsø MF radar (70°N, 19°E) and Esrange "Meteor" radar (68°N, 21°E). The radar-spacings range from 125-270km, making it unique for studies of wind variability associated with small-scale waves, comparisons of large-scale ...

    • Mesospheric dust and its secondary effects as observed by the ESPRIT payload 

      Havnes, Ove; Surdal, L. H.; Philbrick, C. R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)

    • Mesospheric temperatures and sodium properties measured with the ALOMAR Na lidar compared with WACCM 

      Dunker, Tim; Hoppe, Ulf-Peter; Feng, Wuhu; Plane, John M.C.; Marsh, Daniel R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-16)
      We present a comparison of the temperature and sodium layer properties observed by the ALOMAR Na lidar (69.3°N, 16.0°E) and simulated by the Whole Atmosphere Community Climate Model with specified dynamics and implemented sodium chemistry (WACCM-Na). To constrain the meteorological fields below 60 km, we use MERRA and GEOS-5. For the years 2008 to 2012, we analyse daily averages of temperature ...

    • The Meta-Evaluation Problem in Explainable AI: Identifying Reliable Estimators with MetaQuantus 

      Wickstrøm, Kristoffer Knutsen; Höhne, Marina Marie-Claire (Journal article; Tidsskriftartikkel, 2023)
      Explainable AI (XAI) is a rapidly evolving field that aims to improve transparency and trustworthiness of AI systems to humans. One of the unsolved challenges in XAI is estimating the performance of these explanation methods for neural networks, which has resulted in numerous competing metrics with little to no indication of which one is to be preferred. In this paper, to identify the most reliable ...

    • Metasurface supporting quasi-BIC for optical trapping and Raman-spectroscopy of biological nanoparticles 

      Hasan, Md Rabiul; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel, 2023-02-09)
      Optical trapping combined with Raman spectroscopy have opened new possibilities for analyzing biological nanoparticles. Conventional optical tweezers have proven successful for trapping of a single or a few particles. However, the method is slow and cannot be used for the smallest particles. Thus, it is not adapted to analyze a large number of nanoparticles, which is necessary to get statistically ...

    • Method for detection of leads from Sentinel-1 SAR images 

      Murashkin, Dmitrii; Spreen, Gunnar; Huntemann, Marcus; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-05)
      The presence of leads with open water or thin ice is an important feature of the Arctic sea ice cover. Leads regulate the heat, gas and moisture fluxes between the ocean and atmosphere and are areas of high ice growth rates during periods of freezing conditions. Here, an algorithm providing an automatic lead detection based on synthetic aperture radar images is described that can be applied to a ...

    • A method to improve high-resolution sea ice drift retrievals in the presence of deformation zones 

      Griebel, Jakob; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-12)
      Retrievals of sea ice drift from synthetic aperture radar (SAR) images at high spatial resolution are valuable for understanding kinematic behavior and deformation processes of the ice at different spatial scales. Ice deformation causes temporal changes in patterns observed in sequences of SAR images; which makes it difficult to retrieve ice displacement with algorithms based on correlation and ...

    • MIDAS-W: a workstation-based incoherent scatter radar data aquisition system. 

      Holt, J.M.; Grydeland, Tom; Erickson, P.J.; Gorczyca, A.M. (Journal article; Tidsskriftartikkel, 2000)
      The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS) is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate hardware and low-level software implementation details from higher levels of the system. Inherent in this is the idea that implementation details can easily be changed in response to ...