Fakultet for naturvitenskap og teknologi: Nye registreringer
Viser treff 2701-2720 av 5336
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Evaluating the performance of raw and epoch non-wear algorithms using multiple accelerometers and electrocardiogram recordings
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-03)Accurate detection of accelerometer non-wear time is crucial for calculating physical activity summary statistics. In this study, we evaluated three epoch-based non-wear algorithms (Hecht, Troiano, and Choi) and one raw-based algorithm (Hees). In addition, we performed a sensitivity analysis to provide insight into the relationship between the algorithms’ hyperparameters and classification performance, ... -
Late Devonian–Carboniferous faulting and controlling structures and fabrics in NW Finnmark
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-10)In the SW Barents Sea, Devonian–Carboniferous collapse led to the formation of major basins and faults, e.g., the Hammerfest Basin bounded by the Troms–Finnmark Fault Complex, and rhomboid- to sigma-shaped (half-)grabens on the Finnmark Platform. High-resolution aeromagnetic and bathymetry data from the shallow shelf show that analogue fault systems are present in coastal and onshore areas of NW ... -
Exploring the temporal variation of the solar quadrupole moment from relativistic gravitation contributions: A fortuitous circumstance?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-08)Due to its oblateness, the Sun carries a solar quadrupole moment playing a key role at the crossroad of fundamental solar physics, astrometry and celestial mechanics. There is nowadays a general agreement on its order of magnitude ( ≈2×10-7 ), but its temporal dependence is still poorly known. Helioseismology led to a variation within the solar cycle by less than 0.04%, not yet ... -
Ice-sheet Dynamics and Postglacial Sedimentary Processes of Coastal Søre Sunnmøre, Southwest Norway
(Master thesis; Mastergradsoppgave, 2020-05-15)Submarine glacial landforms have been identified and mapped in order to reconstruct ice sheet dynamics and to describe postglacial sedimentary processes of coastal Søre Sunnmøre in southwestern Norway which lies between 62 and 62.5⁰N. Landform identification has been accomplished through analysis of high-resolution multibeam echosounder (MBES) bathymetric data, backscatter data, LiDAR data, video ... -
Fluid flow and faulting along the northern margin of the Loppa High
(Master thesis; Mastergradsoppgave, 2020-05-15)The Barents Sea is a large epicontinental sea and petroliferous basin, which is fairly unexplored compared to other regions of the Norwegian Continental Shelf (NCS). The structural configuration of the SW Barents Sea is characterized by a complex mosaic of structural highs, platforms and basins, reflecting the interplay between multiple tectonic phases. Late Cenozoic glacially induced subsidence and ... -
Regulering av brokommunikasjon i skipsfart. En casestudie av den menneskelige faktoren kommunikasjon
(Master thesis; Mastergradsoppgave, 2019-10-28)Maritim skipsfart er en industri preget av høy risiko for ulykker. Regulering av risiko er derfor en viktig prosess for å forebygge menneskelige, teknologiske og organisatoriske feil. Å finne en egnet måte å regulere risiko kan imidlertid være krevende for regulatorer. I denne studien illustreres dette ved å se nærmere på regulering av brokommunikasjon på skipsbro. Forskning på menneskelige faktorer ... -
Typical hydrodynamic models for aquaculture nets: A comparative study under pure current conditions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-17)The net is regarded as the most critical component in marine aquaculture facilities as it is the only barrier which protects the environment from fish escapes. Accurate predictions of the net cage deformation and drag force on the nets are needed, both for ensuring fish welfare and for dimensioning of the mooring system. Thus, an appropriate hydrodynamic model is essential. In practice, two types ... -
Data-Driven and Artificial Intelligence (AI) Approach for Modelling and Analyzing Healthcare Security Practice: A Systematic Review
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03)Data breaches in healthcare continue to grow exponentially, calling for a rethinking into better approaches of security measures towards mitigating the menace. Traditional approaches including technological measures, have significantly contributed to mitigating data breaches but what is still lacking is the development of the “human firewall,” which is the conscious care security practices of the ... -
A dual linear autoencoder approach for vessel trajectory prediction using historical AIS data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)Advances in artificial intelligence are driving the development of intelligent transportation systems, with the purpose of enhancing the safety and efficiency of such systems. One of the most important aspects of maritime safety is effective collision avoidance. In this study, a novel dual linear autoencoder approach is suggested to predict the future trajectory of a selected vessel. Such predictions ... -
Microbial communities from Arctic marine sedimentsrespond slowly to methane addition duringex situenrichments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-15)Anaerobic methanotrophic archaea (ANME) consume methane in marine sediments, limiting its release to the water column, but their responses to changes in methane and sulfate supplies remain poorly constrained. To address how methane exposure may affect microbial communities and methane‐ and sulfur‐cycling gene abundances in Arctic marine sediments, we collected sediments from offshore Svalbard that ... -
Geological controls of giant crater development on the Arctic seafloor
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)Active methane seepage occurs congruent with a high density of up to 1 km-wide and 35 m deep seafloor craters (>100 craters within 700 km<sup>2</sup> area) within lithified sedimentary rocks in the northern Barents Sea. The crater origin has been hypothesized to be related to rapid gas hydrate dissociation and methane release around 15–12 ka BP, but the geological setting that enabled and possibly ... -
An AIS-Based Multiple Trajectory Prediction Approach for Collision Avoidance in Future Vessels
(Peer reviewed; Bok; Chapter, 2019-11-11)This study presents a method to predict the future trajectory of a target vessel using historical AIS data. The purpose of such a prediction is to aid in collision avoidance in future vessels. The method presented in this study extracts all trajectories present in an initial cluster centered about a vessel position. Features for each trajectory are then generated using Principle Component Analysis ... -
Symmetric Non-Negative Forms and Sums of Squares
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)We study symmetric non-negative forms and their relationship with symmetric sums of squares. For a fixed number of variables <i>n</i> and degree 2<i>d</i>, symmetric non-negative forms and symmetric sums of squares form closed, convex cones in the vector space of <i>n</i>-variate symmetric forms of degree 2<i>d</i>. Using representation theory of the symmetric group we characterize both cones in a ... -
Radio occultation observations of the solar corona over 1.60-1.86R⊙: Faraday rotation and frequency-shift analysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-02)The study of coronal energy transport, central to the solar wind acceleration problem, relies upon accurate representation of magnetic fields and plasma electron densities. This information is difficult to obtain in middle‐to‐lower coronal regions that may contain complex magnetic structures. Faraday rotation (FR) solar radio occultation observations, which reveal line‐of‐sight (LOS) integrated ... -
Is there a Climatic Control on Icelandic Volcanism?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-07)The evidence for periods of increased volcanic activity following deglaciation, such as following ice sheet retreat after the Last Glacial Maximum, has been examined in several formerly glaciated areas, including Iceland, Alaska, and the Andean Southern Volcanic Zone. Here we present new evidence supporting the theory that during episodes of cooling in the Holocene, Icelandic volcanic activity ... -
Kvasir-SEG: A Segmented Polyp Dataset
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-24)Pixel-wise image segmentation is a highly demanding task in medical-image analysis. In practice, it is difficult to find annotated medical images with corresponding segmentation masks. In this paper, we present Kvasir-SEG: an open-access dataset of gastrointestinal polyp images and corresponding segmentation masks, manually annotated by a medical doctor and then verified by an experienced ... -
Learning representations of multivariate time series with missing data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-19)Learning compressed representations of multivariate time series (MTS) facilitates data analysis in the presence of noise and redundant information, and for a large number of variates and time steps. However, classical dimensionality reduction approaches are designed for vectorial data and cannot deal explicitly with missing values. In this work, we propose a novel autoencoder architecture based on ... -
Biogeochemical Consequences of Nonvertical Methane Transport in Sediment Offshore Northwestern Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-21)A site at the gas hydrate stability limit was investigated offshore northwestern Svalbard to study methane transport in sediment. The site was characterized by chemosynthetic communities (sulfur bacteria mats, tubeworms) and gas venting. Sediments were sampled with in situ porewater collectors and by gravity coring followed by analyses of porewater constituents, sediment and carbonate geochemistry, ... -
ReSpect: Relativistic spectroscopy DFT program package
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-11)With the increasing interest in compounds containing heavier elements, the experimental and theoretical community requires computationally efficient approaches capable of simultaneous non-perturbative treatment of relativistic, spin-polarization, and electron correlation effects. The ReSpect program has been designed with this goal in mind and developed to perform relativistic density functional ... -
Late Cenozoic erosion in the SW Barents Sea, and its influence on salt movement
(Master thesis; Mastergradsoppgave, 2019-05-15)The late Cenozoic evolution of the southwestern Barents Sea shelf includes periods of uplift, erosion and glaciations. This part of the stratigraphy has been studied using 2D and 3D seismic data, with emphasis on the interplay between uplift, erosion and glaciations and salt movement. The study area comprises the Svalis, Samson and Norvarg domes and the Nordkapp Basin, where halokinesis has been a ...