Viser treff 2936-2955 av 4753

    • Object detection at the edge 

      Mathiassen, Truls (Mastergradsoppgave; Master thesis, 2020-11-10)
      While monitoring rodents in the Arctic Tundra to evaluate if climate changes affect the ecosystem. The camera-traps of the coat project generates image data in large scale each year. To manually examine the data in regards to label- ing is a tedious and time-consuming job, and a more efficient and automated tool for the task is required. In this thesis we presents the architecture, design and ...
    • Object detection neural network improves Fourier ptychography reconstruction 

      Ströhl, Florian; Jadhav, Suyog; Ahluwalia, Balpreet Singh; Agarwal, Krishna; Prasad, Dilip K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-23)
      High resolution microscopy is heavily dependent on superb optical elements and superresolution microscopy even more so. Correcting unavoidable optical aberrations during post-processing is an elegant method to reduce the optical system’s complexity. A prime method that promises superresolution, aberration correction, and quantitative phase imaging is Fourier ptychography. This microscopy technique ...
    • Object-based detection of linear kinematic features in sea ice 

      Linow, Stefanie; Dierking, Wolfgang Fritz Otto (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-18)
      Inhomogenities in the sea ice motion field cause deformation zones, such as leads, cracks and pressure ridges. Due to their long and often narrow shape, those structures are referred to as Linear Kinematic Features (LKFs). In this paper we specifically address the identification and characterization of variations and discontinuities in the spatial distribution of the total deformation, which ...
    • An objective global climatology of polar lows based on reanalysis data 

      Stoll, Patrick; Graversen, Rune; Noer, Gunnar; Hodges, Kevin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-16)
      Here we present an objective global climatology of polar lows. In order to obtain objective detection criteria, the efficacy of several parameters for separating polar lows from other cyclones has been compared. The comparison and the climatology are based on the ERA‐Interim reanalysis from 1979 ‐ 2016 and the high‐resolution Arctic System Reanalysis from 2000 ‐ 2012. The most effective parameters ...
    • Objective Momentum Barriers in Wall Turbulence 

      Aksamit, Nikolas Olson; Haller, George (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-28)
      We use the recent frame-indifferent theory of diffusive momentum transport to identify internal barriers in wall-bounded turbulence. Formed by the invariant manifolds of the Laplacian of the velocity field, the barriers block the viscous part of the instantaneous momentum flux in the flow. We employ the level sets of single-trajectory Lagrangian diagnostic tools, the trajectory rotation average ...
    • Objekt-adapter og programmeringsgrensesnitt for ANSAware applikasjoner 

      Hanssen, Øyvind (Master thesis; Mastergradsoppgave, 1994)
      I denne hovedfagsavhandlinga undersøkes avbildningsmekanismer mellom ANSAware applikasjoner og en føderativ omgivelse. Dette gjøres innefor rammen av ODS-gruppas arbeid med samvirkende informasjonssystemer. For å få kunnskap om problemområdet og om hvordan avbildning effektivt kan utføres, utvikles et rammeverk for modellering, design og implementasjon av avbildningsmekanismer. Vi fokuserer spesielt ...
    • OBS Data Analysis to Quantify Gas Hydrate and Free Gas in the South Shetland Margin (Antarctica) 

      Song, Sha; Tinivella, Umberta; Giustiniani, Michela; Singhroha, Sunny; Bünz, Stefan; Cassiani, Giorgio (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-25)
      The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom ...
    • Observation of mesospheric dust and ionospheric conditions during the G-chaser rocket campaign 

      Trollvik, Henriette Marie Tveitnes; Gunnarsdottir, Tinna; Mann, Ingrid; Olsen, Sveinung viggo; Restad, Erlend; Antonsen, Tarjei; Fredriksen, Åshild; Eilertsen, Yngve; Havnes, Ole; Hansen, Rikke; Floer, Markus; Bjørk, Arne; Bootby, Christopher; Latteck, Ralph (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10)
      SPID, Smoke Particle Impact Detector, is a Faraday cup detector designed to measure nanometer-sized meteoric smoke particles during rocket flights. We report measurements made with SPID during the G-Chaser student rocket campaign 13 January 2019 and describe the design of the SPID instruments. Model calculations of dust trajectories within the detector result in an effective crosssection of 0.97 for ...
    • Observation of mesospheric dust and ionospheric conditions during the G-chaser rocket campaign 

      Trollvik, Henriette Marie Tveitnes; Gunnarsdottir, Tinna; Mann, Ingrid; Olsen, Sveinung viggo; Restad, Erlend; Antonsen, Tarjei; Havnes, Ove; Fredriksen, Åshild; Boothby, Christoffer; Björk, Arne; Hansen, Rikke Hedelund; Floer, Markus; Eilertsen, Yngve; Latteck, Ralph (Conference object; Konferansebidrag, 2019)
      SPID, Smoke Particle Impact Detector, is a Faraday cup detector designed to measure nanometer-sized meteoric smoke particles during rocket flights. We report measurements made with SPID during the G-Chaser student rocket campaign 13 January 2019 and describe the design of the SPID instruments. Model calculations of dust trajectories within the detector result in an effective cross section of 0.97 ...
    • Observations of auroral plasma lines 

      Grydeland, Tom (Master thesis; Mastergradsoppgave, 1998-03-01)
      The thesis describes observations of strongly enhanced incoherent scatter plasma lines in the auroral ionosphere which were made with the EISCAT UHF radar in 1985. The linear theory of plasma instabilities is reviewed, and several possible explanations are discussed. The observations were found to be of insufficient resolution to unambiguously resolve which one would be the correct explanation. ...
    • Observations of HF-induced instability in the auroral E region 

      Schlatter, Nicola M.; Ivchenko, Nickolay; Gustavsson, Björn Johan; Leyser, Thomas; Rietveld, Michael T (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Enhancements were observed in backscattered radar power during an ionospheric heating experiment from two distinct altitude regions in the auroral E region above Tromsø. For the experiment the EISCAT Tromsø heater was operated with O mode and X mode alternated at 4.04 MHz, close to the 3rd electron gyroharmonic. Ion-line data recorded with the EISCAT UHF radar reveal different temporal ...
    • Observations of plasma density structures in association with the passage of traveling convection vortices and the occurrence of large plasma jets. 

      Van Eyken, A.P.; Valladares, C.E.; Alcaydé, D.; Rodriguez, J.V.; Ruohoniemi, J.M. (Journal article; Peer reviewed; Tidsskriftartikkel, 1999)
      We report important results of the first campaign specially designed to observe the formation and the initial convection of polar cap patches. The principal instrumentation used in the experiments comprised the EISCAT, the Sondrestrom, and the Super DARN network of radars. The experiment was conducted on February 18, 1996 and was complemented with additional sensors such as the Greenland chain of ...
    • Observations of the urban boundary layer in a cold climate city 

      Varentsov, Mikhail; Konstantinov, Pavel; Repina, I.; Artamonov, Arseny; Pechkin, Alexander Sergeevich; Ezau (Esau), Igor; Baklanov, Aleksander (Journal article; Tidsskriftartikkel, 2022-11-30)
      Cold environment supports a large diversity of local climates. Among them, urban climates in northern cities stand out for their pronounced warm temperature anomaly known as the Urban Heat Island (UHI). UHI in northern cities has been already studies through satellite images and in-situ observations in the urban canopy layer (UCL). Yet, the vertical structure of the urban atmospheric boundary layer ...
    • Observations of thermospheric neutral winds within the polar cusp and the auroral oval using a Doppler imaging system (DIS). 

      Henriksen, K.; Rees, D.; Smith, R.W.; Signernes, F.; Brandstrom, U.; Harris, M.; Maskall, G. (Journal article; Tidsskriftartikkel, 1998)
      Two Doppler imaging systems (DIS) or wide-field imaging Fabry-Perot interferometers (FPI), have recently been commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard, and the second at the IRF, Kiruna, Sweden. These instruments can provide wide-field (600 * 800 km) images of neutral wind flows in the upper thermosphere, by measuring the Doppler shift of the atomic oxygen forbidden ...
    • Observatoriet i 80-årene 

      Trulsen, Jan (Journal article; Tidsskriftartikkel, 1980)
      På terskelen til en ny dekade er det naturlig å stille spørsmålet hva Observatoriets fremtidige rolle skal bli. Vil det fortsatt være behov for forskningsinnsats på Observatoriets tradisjonelle fagfelter, eller skal innsatsen etter hvert anta en annen retning? Vi skal forsøke å belyse dette ved først å rette blikket bakover for derigjennom å få øye på de store utviklingslinjer i den internasjonale ...
    • Observed and unobserved heterogeneity in failure data analysis 

      Zaki, Rezgar; Barabadi, Abbas; Barabady, Javad; Qarahasanlou, Ali Nouri (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-08)
      In reality, failure data are often collected under diffract operational conditions (covariates), leading to heterogeneity among the data. Heterogeneity can be classified as observed and unobserved heterogeneity. Un-observed heterogeneity is the effect of unknown, unrecorded, or missing covariates. In most reliability studies, the effect of unobserved covariates is neglected. This may lead to inaccurate ...
    • Observing electric field and neutral wind with EISCAT 3D 

      Stamm, Johann; Vierinen, Juha; Gustavsson, Björn (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-16)
      Measurements of height-dependent electric field (E) and neutral wind (u) are important governing parameters of the Earth's upper atmosphere, which can be used to study, for example, how auroral currents close or how energy flows between the ionized and neutral constituents. The new EISCAT 3D (E3D) incoherent scatter radar will be able to measure a three-dimensional ion velocity vector (v) at each ...
    • Observing Mesospheric Turbulence With Specular Meteor Radars: A Novel Method for Estimating Second-Order Statistics of Wind Velocity 

      Vierinen, Juha; Chau, Jorge L.; Charuvil, Harikrishnan; Urco, Miguel; Clahsen, Matthias; Avsarkisov, Victor; Marino, Raffaele; Volz, Ryan (Journal article; Peer reviewed, 2019-07)
      There are few observational techniques for measuring the distribution of kinetic energy within the mesosphere with a wide range of spatial and temporal scales. <br>This study describes a method for estimating the three‐dimensional mesospheric wind field correlation function from specular meteor trail echoes. Each radar echo provides a measurement of a one‐dimensional projection of the wind velocity ...
    • Observing Oil Releases from Platforms Using Synthetic Aperture Radar 

      Skrunes, Stine; Johansson, Malin; Brekke, Camilla (Conference object; Konferansebidrag, 2018)
      Synthetic aperture radar (SAR) is used for operational surveillance of ocean areas and oil spill detection. Oil spills are frequently detected around oil platforms due to the releases of so-called produced water (PW), which is water containing low concentrations of oil that can form surface slicks similar to other oil spills. PW releases are legal within given limits. Understanding the signatures ...
    • Occurence of free gas and focused fluid systems in the Veslemøy High area, SW Barents Sea 

      Pless, Gustav (Master thesis; Mastergradsoppgave, 2009-05-15)
      The high-resolution 3D seismic survey EL0001 allowed to document the subsurface fluid migration system and fluid accumulations within Veslemøy High, SW Barents Sea. Fluids migrate both through Cretaceous and Tertiary sediments, but also through younger glacial sediments. Veslemøy High is a structurally isolated high at the Cretaceous and Tertiary levels bounded by N-S trending west-dipping normal ...