Institutt for fysikk og teknologi: Recent submissions
Now showing items 181-200 of 1294
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Assessing ocean ensemble drift predictions by comparison with observed oil slicks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-16)Geophysical models are cornerstone pieces in marine forecasting of floating objects and pollution, such as marine surface oil slicks. Trajectory forecasts of oil spills inherit the uncertainties from the underlying geophysical forcing. In this work we compare the forecast capabilities of an ocean ensemble prediction system (EPS) to those from a higher resolution deterministic model on ... -
Improving satellite-based monitoring of the polar regions: Identification of research and capacity gaps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-17)We present a comprehensive review of the current status of remotely sensed and in situ sea ice, ocean, and land parameters acquired over the Arctic and Antarctic and identify current data gaps through comparison with the portfolio of products provided by Copernicus services. While we include several land parameters, the focus of our review is on the marine sector. The analysis is facilitated by the ... -
A dataset of direct observations of sea ice drift and waves in ice
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-03)Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 ... -
Gender inequality and self-publication are common among academic editors
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-16)Scientific editors shape the content of academic journals and set standards for their fields. Yet, the degree to which the gender makeup of editors reflects that of scientists, and the rate at which editors publish in their own journals, are not entirely understood. Here, we use algorithmic tools to infer the gender of 81,000 editors serving more than 1,000 journals and 15 disciplines over five ... -
Attention-Based Neural Network for Solving the Green Vehicle Routing Problem in Waste Management
(Master thesis; Mastergradsoppgave, 2023-06-04)The transport sector is a major contributor to the emission of greenhouse gases and air pollution. As urbanization and population growth continue to increase, the demand for transportation services grows, emphasizing the need for sustainable practices. Therefore, incorporating sustainability into the transport sector can effectively reduce its negative impacts on the environment and optimize the ... -
Utilizing batteries in the Norwegian distribution grid
(Master thesis; Mastergradsoppgave, 2023-06-04)Recent research indicates that photovoltaic (PV) induced overvoltage can occur in high PVpenetration low voltage distribution networks, due to reverse power flow from power injected to the grid. Since January 2020, the number of PV installations in Norway has seen a 2.7-fold increase in a rising trend. Simultaneously there have been several reports of grid-overvoltage and PV curtailment in the ... -
Comparison of numerical wind modelling on hectometric and km scales at Kvitfjell wind power plant
(Master thesis; Mastergradsoppgave, 2023-06-01)Evaluating the performance of numerical weather models (NWMs) is crucial to identify the best choice of model for wind resource assessments. This thesis has investigated how well NWMs with different horizontal resolutions reproduced the wind directions, the wind speeds and the associated power production at a wind power plant located in complex terrain. The evaluated models included NORA3, ... -
Unsupervised segmentation of submarine recordings
(Mastergradsoppgave; Master thesis, 2023-06-01)The thesis focuses on the unsupervised segmentation of submarine recordings collected by the Norwegian Polar Institute (NPI) using hydrophones. These recordings consists of various mammal species, along with other phenomena like vessel engines, seismic activity, and moving sea ice. With sparse labeling of the data, a supervised learning approach is not feasible, necessitating the application of ... -
Feasibility analysis of capacity expansion in Skjerka power station based on production simulation in ProdRisk.
(Master thesis; Mastergradsoppgave, 2023-05-31)The Norwegian energy system has traditionally had an energy surplus with a large share of hydro power. Due to increasing demand of power from large scale electrification, the power system is estimated to experience hours of national power deficient in 2030 even with moderate increase of consumption. Extensive increase of variable production renewable power from wind and solar in Northern Europe has ... -
Forecasting Wind Turbine Production Losses due to Icing
(Master thesis; Mastergradsoppgave, 2023-05-31)In order for wind energy producers to avoid the extra costs of inaccurate production estimates for the day-ahead energy market, precise forecasts of power production during the next day have to be made. For renewables such as wind energy, power production is particularly difficult to predict as it depends on the fluctuating wind speed. In addition, forecasting the power production in cold climates ... -
Comparative performance analysis of two high-latitude solar photovoltaic systems
(Master thesis; Mastergradsoppgave, 2023-05-30)The global energy demand and the urgency to limit greenhouse gas emissions require a transition to cleaner energy sources. Solar energy harvesting is a compelling solution because it can harness the sun’s enormous resources. Solar photovoltaic technology is widely adopted worldwide due to being versatile, adaptable, and mature. However, low solar irradiation and harsh weather conditions limit its ... -
Probing power laws in multifrequency AFM
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-17)Quantification of conservative forces in multifrequency atomic force microscopy requires solving the general equations of the theory expressed in terms of the virials of interaction. Power law expressions are commonly utilized when dealing with electrostatic, ferroelectric, magnetic, or long range (van der Waals) forces. Here, we discuss long range forces modeled in terms of power laws (n), where ... -
α-Synuclein fibril and synaptic vesicle interactions lead to vesicle destruction and increased lipid-associated fibril uptake into iPSC-derived neurons
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-15)Monomeric alpha-synuclein (aSyn) is a well characterised protein that importantly binds to lipids. aSyn monomers assemble into amyloid fibrils which are localised to lipids and organelles in insoluble structures found in Parkinson’s disease patient’s brains. Previous work to address pathological aSyn-lipid interactions has focused on using synthetic lipid membranes, which lack the complexity of ... -
Knowledge Gaps and Impact of Future Satellite Missions to Facilitate Monitoring of Changes in the Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-30)Polar-orbiting satellite observations are of fundamental importance to explore the main scientific challenges in the Arctic Ocean, as they provide information on bio-geo-physical variables with a denser spatial and temporal coverage than in-situ instruments in such a harsh and inaccessible environment. However, they are limited by the lack of coverage near the North Pole (Polar gap), the polar night, ... -
Viewing life without labels under optical microscopes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-25)Optical microscopes today have pushed the limits of speed, quality, and observable space in biological specimens revolutionizing how we view life today. Further, specific labeling of samples for imaging has provided insight into how life functions. This enabled label-based microscopy to percolate and integrate into mainstream life science research. However, the use of labelfree microscopy has been ... -
A probabilistic framework for source localization in anisotropic composite using transfer learning based multi-fidelity physics informed neural network (mfPINN)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-17)The practical application of data-driven frameworks like deep neural network in acoustic emission (AE) source localization is impeded due to the collection of significant clean data from the field. The utility of the such framework is governed by data collected from the site and/or laboratory experiment. The noise, experimental cost and time consuming in the collection of data further worsen the ... -
Stochastic modeling of blob-like plasma filaments in the scrape-off layer: Theoretical foundation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-25)A stochastic model for a superposition of uncorrelated pulses with a random distribution of amplitudes, sizes, and velocities is presented. The pulses are assumed to move radially with fixed shape and amplitudes decaying exponentially in time due to linear damping. The pulse velocities are taken to be time-independent but randomly distributed. The implications of a distribution of pulse amplitudes, ... -
Laser-Generated Scholte Waves in Floating Microparticles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-04)This study aims to demonstrate the generation and detection of Scholte waves inside polystyrene microparticles. This was proven using both experimental analysis and COMSOL simulation. Microspheres of different sizes were excited optically with a pulsed laser (532 nm), and the acoustic signals were detected using a transducer (40 MHz). On analyzing the laser-generated ultrasound signals, the results ... -
Different mechanisms of Arctic first-year sea-ice ridge consolidation observed during the MOSAiC expedition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-22)Sea-ice ridges constitute a large fraction of the ice volume in the Arctic Ocean, yet we know little about the evolution of these ice masses. Here we examine the thermal and morphological evolution of an Arctic firstyear sea-ice ridge, from its formation to advanced melt. Initially the mean keel depth was 5.6 m and mean sail height was 0.7 m. The initial rubble macroporosity (fraction of seawater ... -
Non-trace full-F gyro-fluid interchange impurity advection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-01)A full-F isothermal gyro-fluid model and code (which is based on the full distribution function F compared to only small fluctuations) is extended to handle self-consistent coupling of multiple quasi-neutral ion species via the polarisation equation in the long wavelength approximation. The numerical model is used to determine two-dimensional interchange driven ‘blob’ transport in a plasma with ...