Viser treff 361-380 av 5425

    • AI-Based Cropping of Ice Hockey Videos for Different Social Media Representations 

      Houshmand Sarkhoosh, Mehdi; Dorcheh, Sayed Mohammad Majidi; Midoglu, Cise; Shafiee Sabet, Saeed; Kupka, Tomas; Johansen, Dag; Riegler, Michael; Halvorsen, Pål (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 

      Nozal Cañadas, Rafael Adolfo (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 

      Losada, Juan Manuel; Helgeland, Aurora Driveklepp; Terry, J.L.; Garcia, Odd Erik (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 

      Oliveira, Pedro; Moura, Felipe Arruda; Matias Do Vale Baptista, Ivan Andre; Nakamura, Fábio Yuzo; Afonso, José (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 

      Hong, Wei-Li; Lepland, Aivo; Cremiere, Antoine; Kirsimäe, Kalle; Stüeken, Eva E.; Dumont, Matthew; Block, Heidi E.; Rae, James W. B. (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 

      Cheng, I; Achilleos, Nicholas; Blanco-Cano, X; Bertucci, Cesar; Sergis, N; Paranicas, Chris; Guio, Patrick (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-10-03)
    • Waves and Instabilities in Saturn’s magnetosheath: 2 Dispersion relation analysis 

      Cheng, I; Achilleos, Nicholas; Blanco-Cano, X; Bertucci, Cesar; Guio, Patrick (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 

      Aa, Ercha; Huba, Joseph; Zhang, Shun-Rong; Coster, Anthea J.; Erickson, Philip J.; Goncharenko, Larisa P.; Vierinen, Juha-Pekka; Rideout, William (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 

      Aksamit, Nikolas Olson; Katurji, Marwan; Zhang, Jiawei (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 

      Murtza, Iqbal; Kim, Jin-Young; Adnan, Muhammad (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 

      Andreassen, Karin Marie; Ruppel, Carolyn; Liebner, Susanne; Hodson, Andrew; Knies, Jochen Manfred (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 

      Uchman, Alfred; Hanken, Nils-Martin (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 

      Santos, A; Achilleos, Nicholas; Millas, Dimitrios; Dunn, W; Guio, Patrick; Arridge, Christopher (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 ...
    • Defending Against Poisoning Attacks in Federated Learning with Blockchain 

      Dong, Nanqing; Wang, Zhipeng; Sun, Jiahao; Kampffmeyer, Michael Christian; Knottenbelt, William; Xing, Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-18)
      In the era of deep learning, federated learning (FL) presents a promising approach that allows multiinstitutional data owners, or clients, to collaboratively train machine learning models without compromising data privacy. However, most existing FL approaches rely on a centralized server for global model aggregation, leading to a single point of failure. This makes the system vulnerable to ...
    • Machine learning for gap-filling in greenhouse gas emissions databases 

      Cullen, Luke; Marinoni, Andrea; Cullen, Jonathan (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-10)
      Greenhouse gas (GHG) emissions datasets are often incomplete due to inconsistent reporting and poor transparency. Filling the gaps in these datasets allows for more accurate targeting of strategies aiming to accelerate the reduction of GHG emissions. This study evaluates the potential of machine learning methods to automate the completion of GHG datasets. We use three datasets of increasing complexity ...
    • Near-optimality and robustness in energy systems modelling 

      van Greevenbroek, Koen (Doctoral thesis; Doktorgradsavhandling, 2024-11-27)
      <p>To avert a climate disaster, the global energy system quickly needs to transition to net-zero emissions. This will involve drastic reductions in the use of fossil fuels on one hand and electrification based on renewable energy on the other hand. Research has shown that the transition is technically feasible, but presents us with difficult trade-offs and compromises. Since renewable energy is more ...
    • Using power system modelling outputs to identify weather-induced extreme events in highly renewable systems 

      Grochowicz, Aleksander; van Greevenbroek, Koen; Bloomfield, Hannah C. (Journal article; Tidsskriftartikkel, 2024-04-26)
      In highly renewable power systems the increased weather dependence can result in new resilience challenges, such as renewable energy droughts, or a lack of sufficient renewable generation at times of high demand. The weather conditions responsible for these challenges have been well-studied in the literature. However, in reality multi-day resilience challenges are triggered by complex interactions ...
    • Visible light-mediated alkyl radical additions to alkenyl and alkynyl silanes 

      Baussière, Floriane (Doctoral thesis; Doktorgradsavhandling, 2024-11-15)
      <p>Radicals are reactive species that possess a unique reactivity, which enables them to form unusual bonds unreachable by ionic chemistry. In the last twenty years, radical chemistry has benefited from a renewed interest due to the emergence of methods that can initiate radical reactions under mild conditions. Among those, visible light-mediated radical chemistry has become established as a powerful ...
    • Motivation for slushflow classification 

      D'Amboise, Christopher James; Edvardsen Hansen, Vilde; Vick, Louise Mary (Journal article; Tidsskriftartikkel; Peer reviewed, 2024)
      Slushflows are a type of rapid mass movement where water saturated snow flows downhill. Slushflows come in many different sizes, have different triggering mechanisms, and contain debris ranging from simply snow and ice to soil, rock and vegetation. Slushflows are often misclassified as debris flows, wet snow avalanches or river/stream ice jam processes. <p> <p>Norway reports 5 to 20 larger ...
    • Limitations of RAMMS:Debrisflow as a slushflow simulation tool 

      Edvardsen Hansen, Vilde; D'Amboise, Christopher James; Vick, Louise Mary (Journal article; Tidsskriftartikkel; Peer reviewed, 2024)
      Slushflows are defined as water-saturated snow (slush), that moves rapidly downslope as a gravitational mass flow. The high-water content of the flow results in a high density, posing a significant danger to construction, infrastructure and people in its path. To reduce this danger, it is important to predict where slushflows may initiate and travel in the terrain. Numerical modelling of the runout ...