Fakultet for naturvitenskap og teknologi
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Anticipating climate risk in Norwegian municipalities
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-11)Climate change is increasingly being coupled to extreme weather and climate events, with an observed increase in intensity and occurrence of climate-related events. Norway is no exception. Though generally considered quite resilient to climate risk, with favorable conditions for adapting on a national level, studies point to regional and local differences. Applying a mixed methods approach we ... -
Co-located OLCI optical imagery and SAR altimetry from Sentinel-3 for enhanced Arctic spring sea ice surface classification
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-10)The Sentinel-3A and Sentinel-3B satellites, launched in February 2016 and April 2018 respectively, build on the legacy of CryoSat-2 by providing high-resolution Ku-band radar altimetry data over the polar regions up to 81° North. The combination of synthetic aperture radar (SAR) mode altimetry (SRAL instrument) from Sentinel-3A and Sentinel-3B, and the Ocean and Land Colour Instrument (OLCI) imaging ... -
Cross-modality sub-image retrieval using contrastive multimodal image representations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-13)In tissue characterization and cancer diagnostics, multimodal imaging has emerged as a powerful technique. Thanks to computational advances, large datasets can be exploited to discover patterns in pathologies and improve diagnosis. However, this requires efficient and scalable image retrieval methods. Cross-modality image retrieval is particularly challenging, since images of similar (or even the ... -
Overview of the First Pathloss Radio Map Prediction Challenge
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-26)Pathloss quantifies the reduction in power density of a signal radiated from a transmitter. The attenuation is due to large-scale effects such as free-space propagation loss and interactions (e.g., penetration, reflection, and diffraction) of the signal with objects such as buildings, vehicles, trees, and pedestrians in the propagation environment. Many current or planned wireless communications ... -
Automated Sentinel-1 ice type mapping and in-situ validation during the CIRFA-22 cruise
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-13)We present a fully-automated workflow to map sea ice types from Sentinel-1 data and transfer the results in near real-time to the research vessel Kronprins Haakon (KPH) in order to support tactical navigation and decision-making during a research cruise conducted towards Belgica Bank in April and May 2022. We used overlapping SAR and optical imagery to train a pixel-wise classifier for the required ... -
Singular Value Decomposition-based Multiple Model Approach towards Developing Digital Twin Applications in Ship Performance Prediction
(Chapter; Bokkapittel, 2024)Representing the entire operational range of an ocean-going vessel with linear equations is often a formidable task. In this research study, a datadriven localized model is presented for ship performance prediction as a part of the digital twin development. For this purpose, different operational conditions of the vessel, i.e., data clusters, are identified using the Gaussian Mixture Models (GMM) ... -
On Statistical Features of Ice Loads on Fixed and Floating Offshore Structures
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-22)Apart from the mechanisms of ice structure interactions under various scenarios of sea ice conditions and structural configurations, the selection of probabilistic models is crucial in order to cope with the loading uncertainty. Sea ice is the primary contributor to design loads in cold regions. In many cases, ice loads present the highest magnitude. In recent years, the probabilistic study of ice ... -
AI-Based Cropping of Ice Hockey Videos for Different Social Media Representations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-23)Sports multimedia is among the most prominent types of content distributed across social media today, and the retargeting of videos for diverse aspect ratios is essential for a suitable representation on different social media platforms. In this respect, ice hockey is quite challenging due to its agile movement pattern and speed, and because the main reference point (puck) is very small. In this ... -
Epidemiology Network Analysis
(Doctoral thesis; Doktorgradsavhandling, 2024-11-29)<p><i>Research questions</i> The primary objective of this doctoral dissertation is an explorative investigation into the social network dynamics within eight high schools, located in Tromsø and Balsfjord (North Norway), and the extent to which these dynamics contribute to the overall health and well-being of the students, such as in the context of infectious disease spread and the transmission of ... -
A three-point velocity estimation method for two-dimensional coarse-grained imaging data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-09-04)Time delay and velocity estimation methods have been widely studied subjects in the context of signal processing, with applications in many different fields of physics. The velocity of waves or coherent fluctuation structures is commonly estimated as the distance between two measurement points divided by the time lag that maximizes the cross correlation function between the measured signals, but ... -
Variation in Accelerometer-Derived Instantaneous Acceleration Distribution Curves of Elite Male Soccer Players According to Playing Position: A Pilot Study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-09-23)The incorporation of triaxial accelerometers into Global Positioning Systems (GPS) has significantly advanced our understanding of accelerations in sports. However, inter-positional differences are unknown. This study aimed to explore the variability of acceleration and deceleration (Acc) distribution curves according to players’ positions during soccer matches. Thirty-seven male players from a ... -
A Sequential Leaching Protocol for δ11B and Trace Element Analyses of Multi-Phase Carbonate Rocks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-22)Boron geochemistry from biogenic carbonates offer valuable information about ocean pH and CO<sub>2</sub> chemistry. However, application to geological carbonate deposits suffers from analytical difficulties in obtaining geochemical signals exclusively from the carbonate phase. Sequential leaching with reagents and acids has the potential to overcome such an issue. There is, however, little systematic ... -
Waves and Instabilities in Saturn's Magnetosheath: 1 Mirror Mode Waves and Their Impact on Magnetopause Reconnection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-03) -
Waves and Instabilities in Saturn’s magnetosheath: 2 Dispersion relation analysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-03) -
Multi-Instrument and SAMI3-TIDAS Data Assimilation Analysis of Three-Dimensional Ionospheric Electron Density Variations During the April 2024 Total Solar Eclipse
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-31)This paper conducts a multi-instrument and data assimilation analysis of the three-dimensional ionospheric electron density responses to the total solar eclipse on 08 April 2024. The altitude-resolved electron density variations over the continental US and adjacent regions are analyzed using the Millstone Hill incoherent scatter radar data, ionosonde observations, Swarm in situ measurements, and a ... -
Understanding Coherent Turbulence and the Roll-Cell Transition With Lagrangian Coherent Structures and Frame-Indifferent Fluxes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-09-18)We present the first analysis of frame-indifferent (objective) fluxes and material vortices in Large Eddy Simulations of atmospheric boundary layer turbulence. We extract rotating fluid features that maintain structural coherence over time for near-neutral, transitional, and convective boundary layers. In contrast to traditional analysis of coherent structures in turbulent boundary layers, we provide ... -
Predicting the Performance of Ensemble Classification Using Conditional Joint Probability
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-21)In many machine learning applications, there are many scenarios when performance is not satisfactory by single classifiers. In this case, an ensemble classification is constructed using several weak base learners to achieve satisfactory performance. Unluckily, the construction of the ensemble classification is empirical, i.e., to try an ensemble classification and if performance is not ... -
Editorial: Natural methane emissions in a changing arctic – implications for climate and environment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-23)Natural methane emissions have received significant attention in recent years due to the documented increase in atmospheric concentrations of methane and its elevated global warming potential relative to CO2. Over the past decades, the Arctic has been warming nearly four times faster than the rest of the planet (Rantanen et al., 2022). Arctic amplification of global warming drives a pressing need ... -
Cambrian-Ordovician trace fossils of the Basissletta region, northeast Spitsbergen, Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-29)Trace fossils of the Cambrian–Ordovician sedimentary succession of the Basissletta region, northeast Spitsbergen, Svalbard, belong to three ichnoassemblages. The first one, composed of Monocraterion and Diplocraterion, belongs to the Skolithos ichnofacies and characterises sandstones of the Tokammane Formation (lower Cambrian: Terreneuvian) deposited in a shallow subtidal setting. The overlying ... -
Characterising the magnetic and plasma environment upstream of Ganymede
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-17)We present an application of the latest UCL‐AGA magnetodisc model (MDISC) to the study of the magnetic and plasma conditions in the near‐Ganymede space. By doing this, we provide a comparison with measurements from Juno's most recent flyby of the Jovian moon, perijove 34 (PJ34). We find good agreement between the model results and the magnetometer data, pointing toward a hot plasma index value ...