Fakultet for naturvitenskap og teknologi: Nye registreringer
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Shellability and homology of q-complexes and q-matroids
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-09)We consider a q-analogue of abstract simplicial complexes, called q-complexes, and discuss the notion of shellability for such complexes. It is shown that q-complexes formed by independent subspaces of a q-matroid are shellable. Further, we explicitly determine the homology of q-complexes corresponding to uniform q-matroids. We also outline some partial results concerning the determination of homology ... -
Killing tensors in Koutras-McIntosh spacetimes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-03)The Koutras–McIntosh family of metrics include conformally flat pp-waves and the Wils metric. It appeared in a paper of 1996 by Koutras–McIntosh as an example of a pure radiation spacetime without scalar curvature invariants or infinitesimal symmetries. Here we demonstrate that these metrics have no 'hidden symmetries', by which we mean Killing tensors of low degrees. For the particular case of Wils ... -
The process of integrating risk management: usefulness, standardisation and adaptation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-25)In this paper we analyse how a municipality set out to integrate risk management throughout an organisation with more than 9000 employees in six divisions and over 100 sub-units. An objective was to ensure coherence in risk management related work conducted in various sub-units in the municipality. Being forerunners, those involved had to find their own way. We identify three focus areas of importance ... -
Symmetry Reduction in AM/GM-Based Optimization
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022)The arithmetic mean/geometric mean inequality (AM/GM inequality) facilitates classes of nonnegativity certificates and of relaxation techniques for polynomials and, more generally, for exponential sums. Here, we present a first systematic study of the AM/GM-based techniques in the presence of symmetries under the linear action of a finite group. We prove a symmetry-adapted representation theorem and ... -
Vertical profiles of black carbon and nanoparticles pollutants measured by a tethered balloon in Longyearbyen (Svalbard islands)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-09)Airborne meteorological and aerosol measurements have been performed in Longyearbyen (Svalbard islands) in the summer of 2018, coupling an instrumental aerosol payload with a meteorological radiosonde deployed on a tethered balloon. More than 70 vertical profiles of aerosol and meteorological properties have been recorded up to a maximum altitude of 1.2 km. As a main result, the present work provides ... -
Safety challenges related to autonomous ships in mixed navigational environments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-30)Digitalization and technological advancements have accelerated the development and emergence of autonomous and remotely controlled ships in the maritime transport sector. This type of vessels consists of highly intelligent and adaptive functionalities, equipped with a variety of external sensors and actuators to gain situation awareness, automated control and adaptive maneuvering for achieving more ... -
Storm chasing: Tracking Holocene storminess in southern Sweden using mineral proxies from inland and coastal peat bogs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-25)Severe extratropical winter storms are a recurrent feature of the European climate and cause widespread socioeconomic losses. Due to insufficient long-term data, it remains unclear whether storminess has shown a notable response to changes in external forcing over the past millennia, which impacts our ability to project future storminess in a changing climate. Reconstructing past storm variability ... -
CIRFA Cruise 2022. Cruise report.
(Research report; Forskningsrapport, 2022)This report gives a complete record of all data sets that were collected during the CIRFA cruise 22 April - 9 May 2022, with RV Kronprins Haakon, to the western Fram Strait and the East Greenland Sea. IMR cruise ID 2022704. The CIRFA-cruise 2022 was funded by UiT the Arctic University of Norway, the European Space Agency (RFP Response No 3-17845), the Research Council of Norway (RCN project ... -
Exact Two-Component TDDFT with Simple Two-Electron Picture-Change Corrections: X-ray Absorption Spectra Near L- and M-Edges of Four-Component Quality at Two-Component Cost
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-01)X-ray absorption spectroscopy (XAS) has gained popularity in recent years as it probes matter with high spatial and elemental sensitivities. However, the theoretical modeling of XAS is a challenging task since XAS spectra feature a fine structure due to scalar (SC) and spin–orbit (SO) relativistic effects, in particular near L and M absorption edges. While full four-component (4c) calculations of ... -
Non-linear response of glacier melting to Holocene warming in Svalbard recorded by sedimentary iron (oxyhydr)oxides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-01)The recent acceleration of ice-sheet loss with its direct impact on sea-level rise and coastal ecosystems is of major environmental and societal concern. However, the effect of atmospheric temperature increases on long-term glacier retreat remains poorly defined due to limited historical observations and uncertainties in numerical ice-sheet models, which challenges climate change adaptation planning. ... -
A multi-centre polyp detection and segmentation dataset for generalisability assessment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-06)Polyps in the colon are widely known cancer precursors identifed by colonoscopy. Whilst most polyps are benign, the polyp’s number, size and surface structure are linked to the risk of colon cancer. Several methods have been developed to automate polyp detection and segmentation. However, the main issue is that they are not tested rigorously on a large multicentre purpose-built dataset, one reason ... -
Mineralogical distribution and genetic aspects of cobalt at the active Fåvne and Loki’s Castle seafloor massive sulfide deposits, Arctic Mid-Ocean Ridges
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-16)The demand for responsibly sourced cobalt has increased dramatically as a result of the global transition to ‘fossil-free’ electromobility. However, the distribution, mineralogical expressions and mechanisms of concentration of Co in different types of hydrothermal ore deposits remain poorly constrained, inhibiting resource assessments and exploration. Here we report Co and other metal concentrations ... -
Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-20)Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO<sub>2</sub>. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three ... -
pyndl: Naïve discriminative learning in python
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-15)The pyndl package implements Naïve Discriminative Learning (NDL) in Python. NDL is an incremental learning algorithm grounded in the principles of discrimination learning (Rescorla & Wagner, 1972; Widrow & Hoff, 1960) and motivated by animal and human learning research (e.g. Baayen et al., 2011; Rescorla, 1988). Lately, NDL has become a popular tool in language research to examine large corpora and ... -
Risk and Resilience Assessment of Wind Farms Performance in Cold Climate Regions
(Doctoral thesis; Doktorgradsavhandling, 2023-03-13)Wind energy conversion systems such as wind farms are growing in numbers and capacity all over the globe. The onshore wind energy generation sector witnessed an increase of approximately 144 TWh during 2020, with onshore wind farms capacity addition of 108 GW, which is twice as much as the added capacity during 2019 (IEA, 2021). This staggering increase in capacity imposes higher needs for improved ... -
Weakly supervised semantic segmentation for MRI: exploring the advantages and disadvantages of class activation maps for biological image segmentation with soft boundaries
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-13)Fully supervised semantic segmentation models require pixel-level annotations that are costly to obtain. As a remedy, weakly supervised semantic segmentation has been proposed, where image-level labels and class activation maps (CAM) can detect discriminative regions for specific class objects. In this paper, we evaluated several CAM methods applied to different convolutional neural networks (CNN) ... -
Sedimentology of Neoproterozoic storm-influenced braid deltas, Varanger Peninsula, North Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-30)The oldest part of the upper Riphean (Cryogenian) sedimentary succession of the Varanger Peninsula, North Norway, includes a series of sandstone-dominated units of fluvio-deltaic to shallow-marine origin and thinner, intercalated mudstone-rich units. The sedimentology and stratigraphic understanding of the mudstone-rich units are less complete compared to their sandstone-dominated counterparts. In ... -
The Kernelized Taylor Diagram
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-02)This paper presents the kernelized Taylor diagram, a graphical framework for visualizing similarities between data populations. The kernelized Taylor diagram builds on the widely used Taylor diagram, which is used to visualize similarities between populations. However, the Taylor diagram has several limitations such as not capturing non-linear relationships and sensitivity to outliers. To address ... -
An Integrated Data Analytics Framework for Enhancing the Environmental and Life-cycle Economic Performance in Shipping
(Doctoral thesis; Doktorgradsavhandling, 2023-03-03)<p>Shipping has been recognized as the most efficient mode of transport, carrying over 80% of international trade volume. The shipping industry is at the beginning of one of its greatest energy and technology transition driven by decarbonization drivers in terms of stringent emission regulations and commercial pressure. Digitalization can enable the transition by leveraging Machine Learning (ML) and ... -
A new spectral harmonization algorithm for Landsat-8 and Sentinel-2 remote sensing reflectance products using machine learning: a case study for the Barents Sea (European Arctic)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-12)The synergistic use of Landsat-8 operational land imager (OLI) and Sentinel-2 multispectral instrument (MSI) data products provides an excellent opportunity to monitor the dynamics of aquatic ecosystems. However, the merging of data products from multisensors is often adversely affected by the difference in their spectral characteristics. In addition, the errors in the atmospheric correction (AC) ...