Now showing items 990-1009 of 1261

    • Seasonal energy storage for district heating applications, including simulation and analysis of Borehole Thermal Energy Storage systems 

      Bakken, Nils Joakim Døvre (Master thesis; Mastergradsoppgave, 2018-06-18)
      The objective of this thesis is to analyse different energy storage technologies for seasonal energy storage in combination with district heating. Tromsø receives district heating (Kvitebjørn Varme). Their new heating central at Skattøra burn waste from industry and households in Tromsø and this heat is used to heat water. A part of this excess heat is lost to air during summer because of a lower ...
    • Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70 N, modelled tides (GSWM, CMAM) 

      Hall, Chris; Manson, A.H.; Meek, C.; Hagan, M.; Koshyk, J.; Franke, S.; Fritts, D.; Hocking, W.; Igarashi, K.; MacDougall, J.; Riggin, D.; Vincent, R. (Journal article; Peer reviewed; Tidsskriftartikkel, 2002)
      In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the equator and high northern latitudes: Christmas Island (2° N), Hawaii (22° N), Urbana (40° N), London (43° N), Saskatoon (52° N) and Tromsø (70° N). Common harmonic analysis was applied, ...
    • Secondary charging effects due to icy dust particle impacts on rocket payloads 

      Bekele, Meseret Kassa; Rapp, M.; Hartquist, T W; Havnes, Ove (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      We report measurements of dust currents obtained with a small probe and a larger probe during the flight of the ECOMA-4 rocket through the summer polar mesosphere. The payload included two small dust probes behind a larger dust probe located centrally at the front. For certain phases of the payload rotation, the current registered by one of the small dust probes was up to 2 times the current measured ...
    • Segmentation and Unsupervised Adversarial Domain Adaptation Between Medical Imaging Modalities 

      Strauman, Andreas Storvik (Master thesis; Mastergradsoppgave, 2019-07-13)
      Segmenting and labelling tumors in multimodal medical imaging are often vital parts of diagnostics and can in many cases be very labor intensive for clinicians. The effort in advancing time-saving methods in the medical health sector might be of great help for busy clinicians and can maybe even save lives. Furthermore, creating methods that generically, accurately and successfully process unlabelled ...
    • A Segmentation based CFAR detection algorithm using truncated statistics 

      Ding, Tao; Doulgeris, Anthony Paul; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-18)
      Target detection in nonhomogeneous sea clutter environments is a complex and challenging task due to the capture effect from interfering outliers and the clutter edge effect from background intensity transitions. For synthetic aperture radar (SAR) measurements, those issues are commonly caused by multiple targets and meteorological and oceanographic phenomena, respectively. This paper proposes a ...
    • Segmentation of PMSE data using random forests 

      Jozwicki, Dorota; Sharma, Puneet; Mann, Ingrid; Hoppe, Ulf-Peter Jürgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-22)
      EISCAT VHF radar data are used for observing, monitoring, and understanding Earth’s upper atmosphere. This paper presents an approach to segment Polar Mesospheric Summer Echoes (PMSE) from datasets obtained from EISCAT VHF radar data. The data consist of 30 observations days, corresponding to 56,250 data samples. We manually labeled the data into three different categories: PMSE, Ionospheric ...
    • Selecting principal attributes in multimodal remote sensing for sea ice characterization 

      Khachatrian, Eduard; Chlaily, Saloua; Eltoft, Torbjørn; Marinoni, Andrea (Chapter; Bokkapittel, 2021)
      Automatic ice charting cannot be achieved using only SAR modalities. It is fundamental to combine information from other remote sensors with different characteristics for more reliable sea ice characterization. In this paper, we employ principal feature analysis (PFA) to select significant information from multimodal remote sensing data. PFA is a simple yet very effective approach that can be applied ...
    • Selective Imputation for Multivariate Time Series Datasets with Missing Values 

      Blazquez-Garcia, Ane; Wickstrøm, Kristoffer Knutsen; Yu, Shujian; Mikalsen, Karl Øyvind; Boubekki, Ahcene; Conde, Angel; Mori, Usue; Jenssen, Robert; Lozano, Jose A. (Journal article; Tidsskriftartikkel, 2023-01-31)
      Multivariate time series often contain missing values for reasons such as failures in data collection mechanisms. Since these missing values can complicate the analysis of time series data, imputation techniques are typically used to deal with this issue. However, the quality of the imputation directly affects the performance of downstream tasks. In this paper, we propose a selective imputation ...
    • Self-Constructing Graph Convolutional Networks for Semantic Labeling 

      Liu, Qinghui; Kampffmeyer, Michael; Jenssen, Robert; Salberg, Arnt-Børre (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-17)
      Graph Neural Networks (GNNs) have received increasing attention in many fields. However, due to the lack of prior graphs, their use for semantic labeling has been limited. Here, we propose a novel architecture called the Self-Constructing Graph (SCG), which makes use of learnable latent variables to generate embeddings and to self-construct the underlying graphs directly from the input features ...
    • Self-constructing graph neural networks to model long-range pixel dependencies for semantic segmentation of remote sensing images 

      Liu, Qinghui; Kampffmeyer, Michael; Jenssen, Robert; Salberg, Arnt Børre (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-16)
      Capturing global contextual representations in remote sensing images by exploiting long-range pixel-pixel dependencies has been shown to improve segmentation performance. However, how to do this efficiently is an open question as current approaches of utilising attention schemes, or very deep models to increase the field of view, increases complexity and memory consumption. Inspired by recent work ...
    • A self-guided anomaly detection-inspired few-shot segmentation network 

      Salahuddin, Suaiba Amina; Hansen, Stine; Gautam, Srishti; Kampffmeyer, Michael; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-13)
      Standard strategies for fully supervised semantic segmentation of medical images require large pixel-level annotated datasets. This makes such methods challenging due to the manual labor required and limits the usability when segmentation is needed for new classes for which data is scarce. Few-shot segmentation (FSS) is a recent and promising direction within the deep learning literature designed ...
    • Self-similar transport processes in a two-dimensional realization of multiscale magnetic field turbulence 

      Milovanov, Alexander V.; Chiaravalloti, Francesco; Zimbardo, Gaetano (Journal article; Tidsskriftartikkel; Peer reviewed, 2004-12-14)
      We present the results of a numerical investigation of charged-particle transport across a synthesized magnetic configuration composed of a constant homogeneous background field and a multiscale perturbation component simulating an effect of turbulence on the microscopic particle dynamics. Our main goal is to analyze the dispersion of ideal test particles faced to diverse conditions in the turbulent ...
    • Self-Supervised Few-Shot Learning for Ischemic Stroke Lesion Segmentation 

      Tomasetti, Luca; Hansen, Stine; Khanmohammadi, Mahdieh; Engan, Kjersti; Høllesli, Liv Jorunn; Kurz, Kathinka Dæhli; Kampffmeyer, Michael Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-01)
      Precise ischemic lesion segmentation plays an essential role in improving diagnosis and treatment planning for ischemic stroke, one of the prevalent diseases with the highest mortality rate. While numerous deep neural network approaches have recently been proposed to tackle this problem, these methods require large amounts of annotated regions during training, which can be impractical in the medical ...
    • Semi-supervised Classification using Kernel Entropy Component Analysis and the LASSO. 

      Myhre, Jonas Nordhaug (Master thesis; Mastergradsoppgave, 2011-12-15)
      In this thesis we present a new semi-supervised classification technique based on the Kernel Entropy Component Analysis (KECA) transformation and the least absolute shrinkage selection operator (LASSO). The latter is a constrained version of the least squares classifier. Traditional supervised classification techniques only use a limited set of labeled data to train the classifier, thus leaving ...
    • Semi-supervised target classification in multi-frequency echosounder data 

      Choi, Changkyu; Kampffmeyer, Michael; Handegard, Nils Olav; Salberg, Arnt Børre; Brautaset, Olav; Eikvil, Line; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-12)
      Acoustic target classification in multi-frequency echosounder data is a major interest for the marine ecosystem and fishery management since it can potentially estimate the abundance or biomass of the species. A key problem of current methods is the heavy dependence on the manual categorization of data samples. As a solution, we propose a novel semi-supervised deep learning method leveraging a few ...
    • seMLP: Self-Evolving Multi-Layer Perceptron in Stock Trading Decision Making 

      Jun, S.W; Sekh, Arif Ahmed; Quek, Chai; Prasad, Dilip K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-24)
      There is a growing interest in automatic crafting of neural network architectures as opposed to expert tuning to fnd the best architecture. On the other hand, the problem of stock trading is considered one of the most dynamic systems that heavily depends on complex trends of the individual company. This paper proposes a novel self-evolving neural network system called self-evolving Multi-Layer ...
    • Sensitive on-chip methane detection with a cryptophane-A cladded Mach-Zehnder interferometer 

      Dullo, Firehun Tsige; Lindecrantz, Susan; Jagerska, Jana; Hansen, Jørn H; Engqvist, Stig Olov Magnus; Solbø, Stian; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-24)
      We report a methane sensor based on an integrated Mach-Zehnder interferometer, which is cladded by a styrene-acrylonitrile film incorporating cryptophane-A. Cryptophane-A is a supramolecular compound able to selectively trap methane, and its presence in the cladding leads to a 17-fold sensitivity enhancement. Our approach, based on 3 cm-long low-loss Si3N4 rib waveguides, results in a detection limit ...
    • Sensitivity analysis of Gaussian process machine learning for chlorophyll prediction from optical remote sensing 

      Blix, Katalin (Master thesis; Mastergradsoppgave, 2014-05-30)
      The machine learning method, Gaussian Process Regression (GPR), has lately been introduced for chlorophyll content mapping from remotely sensed data. It has been shown that GPR has outperformed other machine learning and empirical methods in accuracy, speed and stability. Moreover, GPR not only estimates the chlorophyll content, it also provides the certainty level of the prediction, allowing the ...
    • A Sensitivity Study of L-Band Synthetic Aperture Radar Measurements to the Internal Variations and Evolving Nature of Oil Slicks 

      Karisari, Vebjørn (Master thesis; Mastergradsoppgave, 2018-06-01)
      This thesis focuses on the use of multi-polarization synthetic aperture radar (SAR) for characterization of marine oil spills. In particular, the potential of detecting internal zones within oil slicks in SAR scenes are investigated by a direct within-slick segmentation scheme, along with a sensitivity study of SAR measurements to the evolving nature of oil slicks. A simple, k-means clustering ...
    • Sensitivity to pressure and methane of a cryptophane-A doped polymer 

      Ingvaldsen, Martin (Master thesis; Mastergradsoppgave, 2015-12-15)
      The principle focus of this thesis is the characterization of an on-chip methane sensor based on a waveguide interferometer. It incorporates cryptophane-A molecules in the waveguide cladding to enhance sensitivity and selectivity towards methane. First, the sensor was characterized for sensitivities to ambient conditions, in particular its temperature and pressure sensitivity. The measurement ...