Viser treff 441-460 av 1276

    • Planetary auroral imaging 

      Nagoshi, Yoshiaki (Mastergradsoppgave; Master thesis, 2021-07-09)
      The interaction of the solar wind and the Earth magnetosphere cause auroras. The energetic electrically charged particles, mostly electrons, accelerate along the Earth magnetic field lines into the upper atmosphere, where they collide with gas atoms, causing them to emit light. Some planets also have auroral emission in their characteristic environment. The Jovian magnetosphere is the largest ...
    • Fisheries acoustics and Acoustic Target Classification - Report from the COGMAR/CRIMAC workshop on machine learning methods in fisheries acoustics 

      Handegard, Nils Olav; Andersen, Lars Nonboe; Brautaset, Olav; Choi, Changkyu; Eliassen, Inge Kristian; Heggelund, Yngve; Hestnes, Arne Johan; Malde, Ketil; Osland, Håkon; Ordonez, Alba; Patel, Ruben; Pedersen, Geir; Umar, Ibrahim; Engeland, Tom Van; Vatnehol, Sindre (Research report; Forskningsrapport, 2021-06-15)
      This report documents a workshop organised by the COGMAR and CRIMAC projects. The objective of the workshop was twofold. The first objective was to give an overview of ongoing work using machine learning for Acoustic Target Classification (ATC). Machine learning methods, and in particular deep learning models, are currently being used across a range of different fields, including ATC. The objective ...
    • A comparison of contact charging and impact ionization in low-velocity impacts: implications for dust detection in space 

      Antonsen, Tarjei; Mann, Ingrid; Vaverka, Jakub; Nouzak, Libor; Fredriksen, Åshild (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-15)
      We investigate the generation of charge due to collision between projectiles with sizes below ∼1 µm and metal surfaces at speeds ∼0.1 to 10 km s−1. This corresponds to speeds above the elastic limit and well below speeds where volume ionization can occur. Impact charge production at these low to intermediate speeds has traditionally been described by invoking the theory of shock wave ionization. By ...
    • Radar observations of space debris in polar orbits 2018–2021. A study on the evolution of the Microsat-R fragments 

      Paulsen, Martinius Ekeland (Master thesis; Mastergradsoppgave, 2021-07-02)
      Orbits are an invaluable resource for the global community. However, space pollution is becoming more pronounced as the accumulation of debris continues. Deliberate collisions are a relevant source contributing to this development. When Microsat-R was destroyed with a missile in 2019, it ejected numerous fragments into orbit. Based on observations made with EISCAT UHF, this thesis will investigate ...
    • Measuring velocities of a surge type glacier with SAR interferometry using ALOS-2 data 

      Karlsen, Truls (Master thesis; Mastergradsoppgave, 2021-06-01)
      In recent years, in-situ measurements on Kongsvegen, a surge-type glacier located in the Kongsfjorden area, have showed an acceleration in the flow speeds of the glacier. This could indicate the onset of a surging event, which presents the opportunity to study the dynamics of a glacier surge using remote sensing techniques with in-situ data for reference. Synthetic aperture radar (SAR) is well suited ...
    • On Trapped Particle Dynamics in Rotating Frames 

      Helgeland, Aurora Driveklepp (Mastergradsoppgave; Master thesis, 2021-07-01)
      The rapid rotation of Jupiter and Saturn, combined with internal source of plasma provided by their moons Io and Enceladus respectively, creates a magnetodisk structure of the planetary magnetic field. The magnetodisk looks like a stretched dipole magnetic field in the equatorial region, where centrifugal force is largest. The centrifugal force, originating in the rotating frame, is known to have ...
    • A Study of Electrical Load Forecasting by Synergetic Time Series Clustering in a Temporal Convolutional Network 

      Aasen, Håvard Sund (Master thesis; Mastergradsoppgave, 2021-06-15)
      In this thesis time series forecasting is reviewed and performed on electrical load time series. The main dataset that is used consists of 4074 load time series, each collected from a secondary substation. The time series in this set cover hourly observations spanning more than 2 years, and these time series all have different patterns, some being more similar to each other. We explore how we ...
    • Analysis of Correlations between Energy Consumption, Structural Specifications and Climate-Induced Variables to increase Energy Efficiency in Households and Buildings through a Prediction Model 

      Rasmussen, Christoffer Stene (Master thesis; Mastergradsoppgave, 2021-05-31)
      In a world where the transition towards increasingly progressive renewable energy sources is of great importance moving towards sustainability for our planet and future generations, a large portion of mundane equipment and machinery will turn to the usage of electricity rather than fossil fuel as a resource. This does however pose some challenges to the infrastructure in place as it increases the ...
    • Cometary plasma science: Open science questions for future space missions 

      Goetz, Charlotte; Herbert, Gunell; Volwerk, Martin; A., Beth; et al, et al, 12 co-authors; Ericksson, A.; Eriksson, A.; Galand, M; Henri, P.; Nilsson, Hans; Simon Wedlund, Cyril; Alho, A.; Andersson, Laila A.; Andre, Nicolas; de Keyser, Johan; Deca, J.; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-07)
      Comets hold the key to the understanding of our Solar System, its formation and its evolution, and to the fundamental plasma processes at work both in it and beyond it. A comet nucleus emits gas as it is heated by the sunlight. The gas forms the coma, where it is ionised, becomes a plasma, and eventually interacts with the solar wind. Besides these neutral and ionised gases, the coma also contains ...
    • Electron Bulk Heating at Saturn’s Magnetopause 

      Cheng, I; Achilleos, Nicholas; Masters, A; Lewis, G; Kane, M; Guio, Patrick (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-25)
      Magnetic reconnection at the magnetopause (MP) energizes ambient plasma via the release of magnetic energy and produces an “open” magnetosphere allowing solar wind particles to directly enter the system. At Saturn, the nature of MP reconnection remains unclear. The current study examines electron bulk heating at MP crossings, in order to probe the relationship between observed and predicted reconnection ...
    • Wind Power Prediction with Machine Learning Methods in Complex Terrain Areas 

      Sæther, Brynhild Bentsen (Master thesis; Mastergradsoppgave, 2021-06-29)
      The increasing amount of intermittant wind energy sources connected to the power grid present several challenges in balancing the power network. Accurate prediction of wind power production is identified as one of the most important measures for balancing the power network while maintaining a sustainable integration of wind power in the power grid. However, the volatile nature of wind makes wind ...
    • Detection and Delineation of Produced Water Slicks in Sentinel-1 Synthetic Aperture Radar Images 

      Saus, Brynjar Andersen (Master thesis; Mastergradsoppgave, 2021-06-21)
      Near oil and gas platforms oil detection services regularly detect oil slicks that are a result of legal releases of produced water. These slicks are usually observed using SAR imagery and the important task of observing and monitoring these slicks is as of now carried out manually by human operators aggregated with reported release information. In this thesis we propose three separate approaches ...
    • Detection of Marine Plastic Debris in the North Pacific Ocean using Optical Satellite Imagery 

      Båtvik, Tora (Master thesis; Mastergradsoppgave, 2021-06-15)
      Plastic pollution is ubiquitous across marine environments, yet detection of anthropogenic debris in the global oceans is in its infancy. Here, we exploit high-resolution multispectral satellite imagery over the North Pacific Ocean and information from GPS-tracked floating plastic conglomerates to explore the potential for detecting marine plastic debris via spaceborne remote sensing platforms. ...
    • Fluorescence fluctuation-based super-resolution microscopy using multimodal waveguided illumination 

      Opstad, Ida Sundvor; Hansen, Daniel Henry; Acuña Maldonado, Sebastian Andres; Ströhl, Florian; Priyadarshi, Anish; Tinguely, Jean-Claude; Dullo, Firehun Tsige; Dalmo, Roy Ambli; Seternes, Tore; Ahluwalia, Balpreet Singh; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-19)
      Photonic chip-based total internal reflection fluorescence microscopy (c-TIRFM) is an emerging technology enabling a large TIRF excitation area decoupled from the detection objective. Additionally, due to the inherent multimodal nature of wide waveguides, it is a convenient platform for introducing temporal fluctuations in the illumination pattern. The fluorescence fluctuation-based nanoscopy technique ...
    • Imputation and classification of time series with missing data using machine learning 

      Dretvik, Vilde Fonn (Mastergradsoppgave; Master thesis, 2021-06-21)
      This work is about classifying time series with missing data with the help of imputation and selected machine learning algorithms and methods. The author has used imputation to replace missing values in two data sets, one containing surgical site infection (SSI) data of 11 types of blood samples of patients over 20 days, and another data set called uwave which contain 3D accelerometer data of several ...
    • Complexity-Entropy Analysis of Chaotic and Intermittent Fluctuations in Physical Systems 

      Eilertsen, Sivert Høgli (Master thesis; Mastergradsoppgave, 2021-06-01)
      Time series from chaotic and stochastic systems share properties which can make it hard to distinguish them from each other. The Complexity-Entropy analysis provides appropriate measures of entropy and complexity and representing the calculated values in the representation space, the Complexity-Entropy plane, have been shown to be able to distinguish between time series of stochastic and chaotic ...
    • Probabilistic Load Forecasting with Deep Conformalized Quantile Regression 

      Jensen, Vilde (Master thesis; Mastergradsoppgave, 2021-06-01)
      The establishment of smart grids and the introduction of distributed generation posed new challenges in energy analytics that can be tackled with machine learning algorithms. The latter, are able to handle a combination of weather and consumption data, grid measurements, and their historical records to compute inference and make predictions. An accurate energy load forecasting is essential to assure ...
    • Investigating the Impact of Susceptibility Artifacts on Adjacent Tumors in PET/MRI through Simulated Tomography Experiments 

      Olsen, Erlend Bredal (Mastergradsoppgave; Master thesis, 2021-06-01)
      For quantitative PET imaging, attenuation correction (AC) is mandatory. Currently, all main vendors of hybrid PET/MRI systems apply a segmentation-based approach to compute a Dixon AC-map based on fat and water images derived from in- and opposed-phase MR-images. Changes in magnetic susceptibility pose major problems for MRI, which may lead to artifacts resulting in tissue misclassification in the ...
    • Extracting Information from Multimodal Remote Sensing Data for Sea Ice Characterization 

      Nilsen, Torjus (Mastergradsoppgave; Master thesis, 2021-06-01)
      Remote sensing is the discipline that studies acquisition, preparation and analysis of spectral, spatial and temporal properties of objects without direct touch or contact. It is a field of great importance to understanding the climate system and its changes, as well as for conducting operations in the Arctic. A current challenge however is that most sensory equipment can only capture one or fewer ...
    • Cross-platform application of a sea ice classification method considering incident angle dependency of backscatter intensity and its use in separating level and deformed ice 

      Guo, Wenkai; Itkin, Polona; Lohse, Johannes; Johansson, Malin; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2021)
      Wide-swath C-band synthetic aperture radar (SAR) has been used for sea ice classification and estimates of sea ice drift and deformation since it first became widely available in the 1990s. Here, we examine the potential to distinguish surface features created by sea ice deformation using ice type classification of SAR data. To perform this task with extended spatial and temporal coverage, we ...