Fakultet for naturvitenskap og teknologi: Recent submissions
Now showing items 21-40 of 4904
-
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 ... -
Optimizing the maintenance threshold in presence of shocks: A numerical framework for systems with non-monotonic degradation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-24)Shocks have attracted considerable interest in reliability and maintenance engineering because of their impact on vulnerable systems. Most industrial systems suffer from both internal degradation caused by fatigue and wearout, and external shocks that often occur randomly due to harsh weather conditions, overloading, etc. Developing maintenance optimization models without taking these stochastic ... -
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 ... -
Orbit Spaces of Weyl Groups Acting on Compact Tori: A Unified and Explicit Polynomial Description
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024)The Weyl group of a crystallographic root system has a multiplicative action on the compact torus. The orbit space of this action is a compact basic semi-algebraic set. We present a polynomial description of this set for the Weyl groups associated to root systems of types A, B, C, D and G. Our description is given through a polynomial matrix inequality. The novelty lies in an approach via Hermite ... -
Symmetries in Polynomial Optimization
(Chapter; Bokkapittel, 2023-12-28)This chapter investigates how symmetries can be used to reduce the computational complexity in polynomial optimization problems. A focus will be specifically given on the Moment-SOS hierarchy in polynomial optimization, where results from representation theory and invariant theory of groups can be used. In addition, symmetry reduction techniques which are more generally applicable are also presented. -
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 ... -
Arctic Freshwater Sources and Ocean Mixing Relationships Revealed With Seawater Isotopic Tracing
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-29)The Arctic Ocean and adjacent seas are undergoing increased freshwater influx due to enhanced glacial and sea ice melt, precipitation, and runoff. Accurate delineation of these freshwater sources is vital as they critically modulate ocean composition and circulation with widespread and varied impacts. Despite this, the delineation of freshwater sources using physical oceanographic measurements (e.g., ... -
Iceberg Detection for Arctic Operations - A Comparison of C- and L-band Wide-Swath SAR
(Doctoral thesis; Doktorgradsavhandling, 2024-09-13)The accurate detection and mapping of icebergs in the Arctic is important for the safety of maritime traffic and offshore infrastructure and for monitoring the health of marine-terminating glaciers. Synthetic Aperture Radar (SAR) images from satellites have proven to be a useful tool for Arctic monitoring, and C-band SAR images are currently used for operational iceberg monitoring in selected ... -
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 ... -
Tidal and seasonal influence on cold seep activity and methanotroph efficiency in the North Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-12)The ocean’s methane emission to the atmosphere is dominated by continental shelves where cold seeps are globally common features. Seeps emit methane into the hydrosphere, but temporal variations and controls of seep activity and the efficiency of the microbial methane filter in the water column are scarce. Here we address these knowledge gaps by measuring whole water column methane inventories and ... -
Unravelling controls on multi-source-to-sink systems: A stratigraphic forward model of the early–middle Cenozoic of the SW Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-10)Source-to-sink dynamics are subjected to complex interactions between erosion, sediment transfer and deposition, particularly in an evolving tectonic and climatic setting. Here we use stratigraphic forward modelling (SFM) to predict the basin-fill architecture of a multi-source-to-sink system based on a state-of-the-art numerical approach. The modelling processes consider key source-to-sink parameters ... -
Glacial troughs as centres of organic carbon accumulation on the Norwegian continental margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-15)The role of continental margin sediments in the carbon cycle and the associated management potential for climate mitigation are currently poorly understood. Previous work has indicated that margin sediments store significant amounts of organic carbon, but few studies have quantified the rates at which organic carbon is accumulated. Here, we use machine learning to make spatial predictions of the ... -
Geological and glaciological controls of 21,700 active methane seeps in the northern Norwegian Barents sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-11)Due to tectonic uplift in the Cenozoic and numerous shelf-wide glaciations during the Quaternary, ∼1–2.5 km of sedimentary overburden has been eroded from the Barents Sea shelf, leading to the exhumation and partial uncapping of hydrocarbon accumulations. Widespread natural gas and oil leakage from the glacially eroded middle-upper Triassic reservoir directly into the water column has been documented ... -
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 ... -
Performance Evaluation of Lightweight Stream Ciphers for Real-Time Video Feed Encryption on ARM Processor
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-25)In resource-intensive Internet of Things applications, Lightweight Stream Ciphers (LWSCs) play a vital role in influencing both the security and performance of the system. Numerous LWSCs have been proposed, each offering certain properties and trade-offs that carefully balance security and performance requirements. This paper presents a comprehensive evaluation of prominent LWSCs, with a focus on ... -
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 ... -
Integration of programming in Norwegian schools: The effects of prior programming experience on students in a university-level programming course
(Master thesis; Mastergradsoppgave, 2024-06-03)In 2020 a curriculum renewal in Norway integrated programming into multiple subjects at both elementary schools and upper secondary schools. This was done with the hopes of improving deep learning and introducing computational thinking to pupils attending the schools. Some criticism has been raised against the decision, with some declaring that this will hurt deep learning and that programming is ... -
AquaTrace: Secure Federated Identifiers for Product Tracing using Blockchain
(Master thesis; Mastergradsoppgave, 2024-05-31)This thesis proposes a secure and resilient system for generating and managing unique identification number series for tracing food products within the Norwegian fishing industry, without relying on a central authority. Given the context of mutual mistrust among stakeholders and the threat of hostile entities, this project proposes a blockchain-based solution to ensure the uniqueness and security ...