Artikler, rapporter og annet (fysikk og teknologi): Recent submissions
Now showing items 461-480 of 947
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Muliggjørende teknologi og rammebetingelser
(Research report; Forskningsrapport, 2018-02-19) -
Malin letar oljespill i ishavet
(Chronicle; Kronikk, 2020-03-13) -
UAV-BORNE UWB RADAR FOR SNOWPACK SURVEYS
(Research report; Forskningsrapport, 2018)In this report we summarize the capabilities and technical characteristics of our UAV-borne UWB radar system, designed for conducting snow surveys. We developed an ultrawideband snow sounder that is capable of imaging snow stratigraphy with a 5 cm range resolution. The radar can be carried by an octocopter UAV in order to carry out airborne snowpack surveys. During a demonstration on Andøya, we ... -
Assessment of High‐Resolution Dynamical and Machine Learning Models for Prediction of Sea Ice Concentration in a Regional Application
(Journal article; Tidsskriftartikkel, 2020-10-17)In this study, the potential for sea ice concentration prediction using machine‐learning methods is investigated. Three different sea ice prediction models are compared: one high‐resolution dynamical assimilative model and two statistical machine‐learning models. The properties of all three models are explored, and the quality of their forecasts is compared. The dynamical model is a state‐of‐the‐art ... -
Auroral Image Classification With Deep Neural Networks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-05)Results from a study of automatic aurora classification using machine learning techniques are presented. The aurora is the manifestation of physical phenomena in the ionosphere‐magnetosphere environment. Automatic classification of <i>millions</i> of auroral images from the Arctic and Antarctic is therefore an attractive tool for developing auroral statistics and for supporting scientists to study ... -
Experimental protocol for sea level projections from ISMIP6 stand-alone ice sheet models
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-23)Projection of the contribution of ice sheets to sea level change as part of the Coupled Model Intercomparison Project Phase 6 (CMIP6) takes the form of simulations from coupled ice sheet–climate models and stand-alone ice sheet models, overseen by the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). This paper describes the experimental setup for process-based sea level change projections ... -
Arctic Field Summer Schools: training and awareness in the Arctic
(Conference object; Konferansebidrag, 2020-01)A series of three summer schools engaged nearly fifty graduate students in exploring science questions related to current Arctic challenges, and brought together leading Arctic researchers from the partner institutions. Each partner organised a Field School and each had their own unique styles and emphasis. This collaboration aimed to deepen the Arctic knowledge of the young generation, and to create ... -
Quantitative assessment of morphology and sub-cellular changes in macrophages and trophoblasts during inflammation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-12)In pregnancy during an inflammatory condition, macrophages present at the feto-maternal junction release an increased amount of nitric oxide (NO) and pro-inflammatory cytokines such as TNF-α and INF-γ, which can disturb the trophoblast functions and pregnancy outcome. Measurement of the cellular and sub-cellular morphological modifications associated with inflammatory responses are important in order ... -
Dust sputtering within the inner heliosphere: a modelling study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-03)The aim of this study is to investigate how sputtering by impacting solar wind particles influence the lifetime of dust particles in the inner heliosphere near the Sun.<p><p> We consider three typical dust materials: silicate, Fe<sub>0.4</sub>Mg<sub>0.6</sub>O and carbon and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. ... -
Can Mineral Oil Slicks Be Distinguished From Newly Formed Sea Ice Using Synthetic Aperture Radar?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-18)In this feasibility study discriminating oil slicks and newly formed sea ice using SAR imagery is investigated, using imagery from the L-band high-resolution Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne and the satellite C-band RADARSAT-2 (RS-2) systems. To determine the separability of these two varying but similar appearing low backscatter ocean surfaces, multi-polarization ... -
Auroral classification ergonomics and the implications for machine learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)The machine-learning research community has focused greatly on bias in algorithms and have identified different manifestations of it. Bias in training samples is recognised as a potential source of prejudice in machine learning. It can be introduced by the human experts who define the training sets. As machine-learning techniques are being applied to auroral classification, it is important to identify ... -
Getting adhesion force maps with an amplitude-modulation AFM in tapping mode
(Research report; Forskningsrapport, 2020-07)Here we demonstrate how to get adhesion force maps with an amplitude-modulation AFM in tapping mode. Our method is tapping mode but it is carried out at ultra-small amplitudes in the presence of surface water layers. The tip is made to vibrated under the water layer in what we call Small Amplitude Small Set-point AM AFM. We show how this is done with an example based on the Cypher scanning probe ... -
CMIP5 model selection for ISMIP6 ice sheet model forcing: Greenland and Antarctica
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-06)The ice sheet model intercomparison project for CMIP6 (ISMIP6) effort brings together the ice sheet and climate modeling communities to gain understanding of the ice sheet contribution to sea level rise. ISMIP6 conducts stand-alone ice sheet experiments that use space- and time-varying forcing derived from atmosphere–ocean coupled global climate models (AOGCMs) to reflect plausible trajectories for ... -
Reconstructing force profiles with an amplitude-modulation AFM in tapping mode
(Research report; Forskningsrapport, 2020-07)Here we demonstrate how to reconstruct force profiles with an amplitude-modulation AFM operated in in standard tapping mode. Our example is based on the Cypher scanning probe microscope from Asylum Research. The method is based on Sader and Katan’s algorithm, but we have implemented an experimental set-up that allows for robust reconstruction. We discuss the details here. -
Explaining decisions of deep neural networks used for fish age prediction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-19)Age-reading of fish otoliths (ear stones) is important for the sustainable management of fish resources. However, the procedure is challenging and requires experienced readers to carefully examine annual growth zones. In a recent study, convolutional neural networks (CNNs) have been demonstrated to perform reasonably well on automatically predicting fish age from otolith images. In the present study, ... -
Large-Scale Detection and Categorization of Oil Spills from SAR Images with Deep Learning
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)We propose a deep-learning framework to detect and categorize oil spills in synthetic aperture radar (SAR) images at a large scale. Through a carefully designed neural network model for image segmentation trained on an extensive dataset, we obtain state-of-the-art performance in oil spill detection, achieving results that are comparable to results produced by human operators. We also introduce a ... -
First observations of the McMurdo-South Pole oblique ionospheric HF channel
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-09)We present the first observations from a new low-cost oblique ionosonde located in Antarctica. The transmitter is located at McMurdo Station, Ross Island, and the receiver at Amundsen–Scott Station, South Pole. The system was demonstrated successfully in March 2019, with the experiment yielding over 30 000 ionospheric echoes over a 2-week period. These data indicate the presence of a stable E layer ... -
On the relation between polarimetric synthetic aperture radar (SAR) features and sea ice melt pond fraction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)In this study we examine the relationship between sea ice melt pond fraction and two polarimetric C-band synthetic aperture radar (SAR) features. Three high-resolution SAR scenes were recorded in the Fram Strait in late summer 2011, covering iceberg-fast first-year and old sea ice. In addition, melt pond fraction was retrieved from photographs recorded during a helicopter flight at the study area. ... -
Mapping sea-ice types from Sentinel-1 considering the surface-type dependent effect of incidence angle
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-23)Automated classification of sea-ice types in Synthetic Aperture Radar (SAR) imagery is complicated by the class-dependent decrease of backscatter intensity with Incidence Angle (IA). In the log-domain, this decrease is approximately linear over the typical range of space-borne SAR instruments. A global correction does not consider that different surface types show different rates of decrease in ... -
Ice extent in sub-arctic fjords and coastal areas from 2001 to 2019 analyzed from MODIS imagery
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-03)Results examining variations in the ice extent along the Norwegian coastline based on the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2001 to 2019, February through May, are presented. A total of 386 fjords and coastal areas were outlined and grouped into ten regions to assess seasonal and long-term trends in ice extent. In addition, three fjords were examined to ...