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norskFakultet for naturvitenskap og teknologi: Recent submissions
Now showing items 3801-3820 of 5439
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Characterisation of palaeosols in the Lower Cretaceous Helvetiafjellet Formation, Svalbard. Palaeo-climatic implications
(Master thesis; Mastergradsoppgave, 2018-05-15)Although the Cretaceous period is known to have been dominated by greenhouse conditions, the Early Cretaceous climatic conditions in Svalbard have been under some debate. Both indicators of warm climate such as coal seams, Ornithopod tracks and warm-water dinoflagellates, and indicators of cold climate such as arctic belemnites, glendonites and ice rafted debris have been reported. This study ... -
Level crossings and excess times due to a superposition of uncorrelated exponential pulses
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-10)A well-known stochastic model for intermittent fluctuations in physical systems is investigated. The model is given by a superposition of uncorrelated exponential pulses, and the degree of pulse overlap is interpreted as an intermittency parameter. Expressions for excess time statistics, that is, the rate of level crossings above a given threshold and the average time spent above the threshold, are ... -
Natural and anthropogenic deposition in Bøkfjorden
(Master thesis; Mastergradsoppgave, 2018-05-15)The aim for this study is to characterise and distinguish natural and anthropogenic deposition in Bøkfjorden, and to identify the spreading and the impact of submarine tailings placements on the seafloor. The analyses are based on the integration of swath bathymetry, high-resolution seismics and multi-proxy analyses of four sediment cores The physical properties, including magnetic susceptibility ... -
Integrated characterization of the Upper Permian Kapp Starostin Formation in central Spitsbergen, Svalbard. From outcrop to geomodel.
(Master thesis; Mastergradsoppgave, 2018-05-14)Natural fractures significantly contribute to improved reservoir quality and recovery factor, especially in carbonate reservoirs. It is important to characterize the matrix and fracture properties, as well as their interaction, in order to describe the natural fracture system and improve the understanding of its effects on a reservoir. This study integrates multi-scale outcrop data from central ... -
Bottom water acidification and warming on the western Eurasian Arctic shelves: Dynamical downscaling projections
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-25)The impacts of oceanic CO2 uptake and global warming on the surface ocean environment have received substantial attention, but few studies have focused on shelf bottom water, despite its importance as habitat for benthic organisms and demersal fisheries such as cod. We used a downscaling ocean biogeochemical model to project bottom water acidification and warming on the western Eurasian Arctic ... -
U-Pb zircon provenance of metamorphosed clastic sediments in the Brusque Metamorphic Complex, Dom Feliciano Belt, southeastern Brazil
(Master thesis; Mastergradsoppgave, 2018-05-15)The Brusque Metamorphic Complex is situated in the northern part of the Dom Feliciano Belt in the state of Santa Catarina, southeastern Brazil. The complex is composed of Neoproterozoic sequences of volcanic and sedimentary rocks, which were folded and metamorphosed at greenschist to low-amphibolite facies conditions. U-Pb dating of detrital zircon grains in five samples of clastic metasedimentary ... -
Metamorphic evolution in external zones of the Dom Feliciano-Kaoko orogenic system. Examples from the Brusque Metamorphic Complex, Dom Feliciano Belt (Brazil) and the Central Kaoko Zone, Kaoko Belt (Namibia)
(Master thesis; Mastergradsoppgave, 2018-05-15)The Brusque Metamorphic Complex in the Dom Feliciano Belt (Brazil) and the Central Kaoko Zone in the Kaoko Belt (Namibia) represent foreland fold- and thrust belts in external parts of the northern Dom Feliciano-Kaoko orogenic system. Petrographic and field observations of metapelitic samples from the Brusque Metamorphic Complex suggests that the western part of the complex can be subdivided into ... -
Combining geophysical data with a mathematical model to describe vertical two-phase flow
(Master thesis; Mastergradsoppgave, 2018-05-15)This thesis combines a geological model with a mathematical model to describe the vertical propagation of a gas plume through layers with different physical properties. The geological model is based on geophysical data from the Sørvestsnaget Basin and the mathematical model is derived based on the classical Buckley-Leverett theory for two-phase flow. The model estimates the velocity of a vertical ... -
Use of 2D-seismic data and available wells to investigate the source potential of the Palaeozoic interval in the Loppa High area, SW Barents Sea
(Master thesis; Mastergradsoppgave, 2018-05-15)While most established plays in the Barents Sea have occurred in the Mesozoic, the Alta and Gohta discoveries prove a new carbonate play concept, with a source rock that does not stem from the Jurassic. Based on depositional environment and TOC values from the Palaeozoic interval a source rock with Top Ørn as its bottom and Top Røye as its top was interpreted. Basin modelling carried out on this ... -
Holocene Glacial Dynamics of the Barentsøya ice cap, Svalbard
(Master thesis; Mastergradsoppgave, 2018-05-13)This study investigates the glacial dynamics of Barentsjøkulen, a small ice cap located on Barentsøya, Svalbard. In order to reconstruct Barentsjøkulen’s glacial history, three geomorphological maps of the glacier forefields of its main outlet glaciers, Besselsbreen, Duckwitzbreen and Freemanbreen, were created. The maps cover a total area of ca. 117 km2 and were generated based on swath bathymetric ... -
Glacial history and forefield development of Aldegondabreen since the Little Ice Age maximum extent
(Master thesis; Mastergradsoppgave, 2018-05-15)A geomorphological map has been produced to investigate the glacial history of Aldegondabreen, a small land terminating valley glacier located on the western coast of Spitsbergen. The glacier has changed its dynamic from a tidewater glacier into a land-terminating glacier during the last advance/retreat cycle, and the focus is therefore to reconstruct the glacial history of this cycle. The map ... -
Oil Spill Dispersion in Full-polarimetric and Hybrid-polarity SAR
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-04)We show that indications of spatial dispersion effects on mineral oil slicks are observed by space-borne multipolarization synthetic aperture radar. This is readily perceived by eye when correlating multipolarization synthetic aperture radar observables with the ship track of the dispersion vessel. We investigate real full-polarimetric (linear transmit/linear receive) as well as simulated and real ... -
Deep Learning: From Data Extraction to Large-Scale Analysis
(Master thesis; Mastergradsoppgave, 2018-05-15)We aim to give an insight into aspects of developing and deploying a deep learning algorithm to automate biomedical image analyses. We anonymize sensitive data from a medical archive system, attempt to replicate and further improve published methods, and scale out our algorithm to support large-scale analyses. Specifically, our contributions are described as follows. First, to anonymize and extract ... -
Intermittent electron density and temperature fluctuations and associated fluxes in the Alcator C-Mod scrape-off layer
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-10)The Alcator C-Mod mirror Langmuir probe system has been used to sample data time series of fluctuating plasma parameters in the outboard mid-plane far scrape-off layer. We present a statistical analysis of one second long time series of electron density, temperature, radial electric drift velocity and the corresponding particle and electron heat fluxes. These are sampled during stationary plasma ... -
Improving Doppler frequency estimation from Envisat data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014-11-06)This paper shows that Envisat ASAR data are degraded by a small periodic variation in gain between internal calibration cycles of the antenna, which introduces a significant bias when we try to estimate line-of-sight surface velocities from the estimated Doppler frequency shifts. We investigate the impact of the gain problems on the derived surface velocity product and propose a simple correction ... -
Cenozoic tectonosedimentary development and erosion estimates for the Barents Sea continental margin, Norwegian Arctic
(Doctoral thesis; Doktorgradsavhandling, 2018-04-26)The Barents Sea shelf has been experienced extensive uplift and erosion in the Cenozoic. However, the pre-glacial erosion has been so far less constrained in comparison to the glacial erosion. This paper aims to better understand the early–middle Cenozoic erosion in the western Barents Sea and the late Cenozoic erosion in the northern Barents Sea by using the mass-balance approach. The study utilizes ... -
Erratum to: Almost complex structures in 6D with nondegenerate Nijenhuis tensors and large symmetry groups
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-23)We correct an error in the second part of Theorem 3 of our original paper. -
Subband Extraction Strategies in Ship Detection With the Subaperture Cross-Correlation Magnitude
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-01-27)The subaperture cross-correlation magnitude (SCM) has previously been proposed as a statistic that improves the contrast between small ship targets and the surrounding sea in synthetic-aperture-radar images. This preprocessing technique utilizes the fast decorrelation of open-water surface ripples on the scale of the SAR wavelength relative to coherent targets such as a ship. However, optimization ... -
Late Weichselian ice-sheet dynamics and deglaciation history of the northern Svalbard margin
(Doctoral thesis; Doktorgradsavhandling, 2018-05-04)This thesis presents new results from marine geological and geophysical studies based on sediment gravity cores, airgun, subbottom acoustic and high-resolution swath bathymetric data from fjords, the continental shelf and slope north of Nordaustlandet, Svalbard. From these records, the glacial landform assemblages as well as the glacial and postglacial sedimentary environments were interpreted. Where ... -
Benthic communities at high-Arctic cold seeps: Faunal response to methane seepage in Svalbard
(Doctoral thesis; Doktorgradsavhandling, 2018-03-20)Cold seeps are chemosynthetic habitats found in both deep sea and shallow ocean-shelves worldwide, including the polar regions. At seeps, hydrocarbons, sulfide, and other reduced compounds emerge from the seafloor, providing energy to fuel chemoautotrophic production. Microbial assemblages, supported by the oxidation and reduction of gases and fluids, form the base of a food web composing unique and ...
