Institutt for fysikk og teknologi: Recent submissions
Now showing items 101-120 of 1399
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High space–time bandwidth product imaging in low coherence quantitative phase microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-22)Current low coherence quantitative phase microscopy (LC-QPM) systems suffer from either reduced field of view (FoV) or reduced temporal resolution due to the short temporal coherence (TC) length of the light source. Here, we propose a hybrid, experimental and numerical approach to address this core problem associated with LC-QPM. We demonstrate high spatial resolution and high phase sensitivity in ... -
Assimilation of satellite swaths versus daily means of sea ice concentration in a regional coupled ocean–sea ice model
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-08)Operational forecasting systems routinely assimilate daily means of sea ice concentration (SIC) from microwave radiometers in order to improve the accuracy of the forecasts. However, the temporal and spatial averaging of the individual satellite swaths into daily means of SIC entails two main drawbacks: (i) the spatial resolution of the original product is blurred (especially critical in periods ... -
Sea ice transport and replenishment across and within the Canadian Arctic Archipelago, 2016-2022
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-07)The Canadian Arctic Archipelago (CAA) serves as both a source and a sink for sea ice from the Arctic Ocean, while also exporting sea ice into Baffin Bay. We use observations from Sentinel-1, RADARSAT-2, the RADARSAT Constellation Mission (RCM), and CryoSat-2, together with the Canadian Ice Service ice charts, to quantify sea ice transport and replenishment across and within the CAA from 2016 to ... -
S-polarized light-sheets improve resolution and light-efficiency in oblique plane microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-12)Oblique plane microscopy (OPM) offers 3D optically sectioned imaging with high spatial- and temporal-resolution while enabling conventional sample mounting. The technique uses a concatenation of three microscopes, two for remote focusing and a tilted tertiary microscope, often including an immersion objective, to image an oblique sample plane. This design induces Fresnel reflections and a reduced ... -
BPI-GNN: Interpretable brain network-based psychiatric diagnosis and subtyping
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-01)Converging evidence increasingly suggests that psychiatric disorders, such as major depressive disorder (MDD) and autism spectrum disorder (ASD), are not unitary diseases, but rather heterogeneous syndromes that involve diverse, co-occurring symptoms and divergent responses to treatment. This clinical heterogeneity has hindered the progress of precision diagnosis and treatment effectiveness in ... -
High-resolution imaging in acoustic microscopy using deep learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-18)Acoustic microscopy is a cutting-edge label-free imaging technology that allows us to see the surface and interior structure of industrial and biological materials. The acoustic image is created by focusing high-frequency acoustic waves on the object and then detecting reflected signals. On the other hand, the quality of the acoustic image's resolution is influenced by the signal-to-noise ratio, the ... -
In-Cloud Icing - A case study at Fagernesfjellet, Norway using Weather Research and Forecasting model and observations
(Chapter; Bokkapittel, 2024)Atmospheric icing poses significant challenges to infrastructure integrity and transportation safety, especially in mountainous regions such as Fagernesfjellet, Norway. This paper presents a comprehensive case study of in-cloud icing over Fagernesfjellet, leveraging hindcast data obtained through dynamic downscaling with the Weather Research and Forecasting (WRF) model alongside observational data. ... -
Resolution enhanced sea ice concentration: a new algorithm applied to AMSR2 microwave radiometry data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-30)Passive-microwave sea ice concentration (SIC) algorithms employ different frequencies and polarisations in their operational implementations. Commonly, these algorithms utilise combinations such as 19/37 GHz, yielding reduced measurement uncertainties but at a coarse spatial resolution. Alternatively, these algorithms can solely use 89 GHz, producing a higher spatial resolution but with increased ... -
Assessing the potential of Eddy detection in MIZ using SAR and Lagrangian modeling: A test case on Fram Strait
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-22)The analysis of ocean eddies in the marginal ice zone via remote sensing and modeling data is a challenging task. However, it is of crucial importance for various scientific applications and anthropogenic activities in the Arctic. Models often struggle to accurately represent eddies near the MIZ due to the intricate nature of sea ice-ocean interactions, unresolved small-scale processes, and ... -
Exploring the universe through dusty visions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-05-13)Dust in space is a universal phenomenon that can be observed within our cosmic neighbourhood. Examples include the dust from the surface of the moon to the further reaches of the outer solar system, such as Saturn’s rings, and even beyond in the galactic environment. Dust in the universe has constantly challenged astronomers’ views of heavenly bodies and phenomena, often obscuring light coming from ... -
Conceptualization of a vehicle-to-grid assisted nation-wide renewable energy system – A case study with spain
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-08)This study explores the potential of Vehicle-to-Grid (V2G) technology in utilizing Electric Vehicle (EV) batteries for energy storage, aiming to fulfil Spain’s 2030 and 2050 energy goals. The validated Simulink model uses 3.15 million EVs in 2030 and 22.7 million EVs in 2050 as primary energy storage. The results show that Spain can achieve its 2030 target of 42 % renewable energy by utilizing ... -
The influence of socio-technical variables on vehicle-to-grid technology
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-04)Vehicle-to-grid technology (V2G) is a novel large scale energy storage option to improve the grid integration of renewable energy sources (RES). Using electric vehicle (EV) batteries to store and provide electricity to the grid, the intermittency of RES can be reduced. However, a successful implementation of this technology depends on various social and technological factors. This study analyses the ... -
Leveraging Explainability Maps for Group-unsupervised Robustness to Spurious Correlations
(Master thesis; Mastergradsoppgave, 2023-08-22)Shortcut learning, the tendency for models to rely on spurious correlations, is a widespread issue in deep learning. Although being a known issue, uncovering the shortcuts present in a dataset can be a difficult task. Over the last few years, explainability methods have been leveraged to find previously unknown shortcuts within mainstream datasets. However, how to best mitigate a model’s reliance ... -
Taxonomy of hybridly polarized Stokes vortex beams
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-15)Structured beams carrying topological defects, namely phase and Stokes singularities, have gained extensive interest in numerous areas of optics. The non-separable spin and orbital angular momentum states of hybridly polarized Stokes singular beams provide additional freedom for manipulating optical fields. However, the characterization of hybridly polarized Stokes vortex beams remains challenging ... -
Abrupt increase in Greenland melt enhanced by atmospheric wave changes
(Journal article; Tidsskriftartikkel, 2024-05-25)Recent Greenland ice-sheet melt constitutes a considerable contribution to global sea-level rise. Observations indicate an approximate zero mass balance of the ice sheet until the late 1990s, after which a strong increase in melting occurred. This cannot be attributed linearly to gradually-increasing global warming. Instead the abrupt shift has been linked to atmospheric circulation changes, although ... -
Propagating information like waves in GNNs
(Master thesis; Mastergradsoppgave, 2024-05-31)Various deep learning architectures are appearing in the field of machine learning with the goal of being able to handle various types of data, or solving inherent problems within the networks. In this thesis, we propose the idea of creating architectures based on physics partial differential equations (PDEs), where we transfer the known properties of PDEs as a method of introducing inductive bias ... -
Bruk av solceller i rehabilitering av gjenreisningsboliger i Nord-Norge – et klimaperspektiv
(Master thesis; Mastergradsoppgave, 2024-05-31)Denne masteroppgaven utforsker potensialet for solceller i rehabilitering av gjenreisningsboliger i Nord-Norge gjennom en detaljert livssyklusanalyse (LCA) for å evaluere miljøpåvirkningen av solskifertak sammenlignet med tradisjonelle skifertak. Ved hjelp av modellering i PVsyst v6.88, ble energiproduksjonen for et system på 11m2 med nominell ytelse 1.4 kW simulert og effekten av viktige ... -
Exploring methane detection with Sentinel-2 data: capabilities for monitoring landfill emissions
(Master thesis; Mastergradsoppgave, 2024-06-01)Methane is an extremely potent greenhouse gas, as it is about 80 times more effective at trapping heat than carbon dioxide. To mitigate global warming and the related consequences, reducing our emissions of methane is crucial. Therefore, being able to detect unknown releases and monitor the effects of emission mitigation efforts is essential. A few satellites with methane monitoring as one of their ... -
Antarctic ice shelf response to ocean tides and atmospheric pressure variations using satellite interferometry
(Master thesis; Mastergradsoppgave, 2024-06-02)Ice shelves, the floating extensions of the Antarctic ice sheet, are supporting the upstream ice and regulates the outflow into the ocean. They are a key component in future predictions of sea level rise, as their direct contact with both the ocean and the atmosphere makes them subject to changing climatic conditions. This thesis aims to investigate how Fimbulisen, a large ice shelf in East ... -
Uncertainty Guided Polygon Generation for Building Detection
(Mastergradsoppgave; Master thesis, 2024-06-01)Enhanced accuracy of building detection algorithms has the potential to benefit a wide array of applications, including urban planning, environmental monitoring, and disaster response efforts. However, building extraction algorithms struggle with robustness due to among others, occlusions from vegetation and shadows of nearby tall buildings, complex building shapes, and a large distributional shift ...