Artikler, rapporter og annet (fysikk og teknologi): Nye registreringer
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Wind power predictions in complex terrain using analog ensembles
(Journal article; Tidsskriftartikkel, 2018) -
Unsupervised domain adaptation for automatic estimation of cardiothoracic ratio
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-26)The cardiothoracic ratio (CTR), a clinical metric of heart size in chest X-rays (CXRs), is a key indicator of cardiomegaly. Manual measurement of CTR is time-consuming and can be affected by human subjectivity, making it desirable to design computer-aided systems that assist clinicians in the diagnosis process. Automatic CTR estimation through chest organ segmentation, however, requires large amounts ... -
Time Series Kernel Similarities for Predicting Paroxysmal Atrial Fibrillation from ECGs
(Journal article; Tidsskriftartikkel, 2018)We tackle the problem of classifying Electrocardiography (ECG) signals with the aim of predicting the onset of Paroxysmal Atrial Fibrillation (PAF). Atrial fibrillation is the most common type of arrhythmia, but in many cases PAF episodes are asymptomatic. Therefore, in order to help diagnosing PAF, it is important to design procedures for detecting and, more importantly, predicting PAF episodes. ... -
The deep kernelized autoencoder
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-18)Autoencoders learn data representations (codes) in such a way that the input is reproduced at the output of the network. However, it is not always clear what kind of properties of the input data need to be captured by the codes. Kernel machines have experienced great success by operating via inner-products in a theoretically well-defined reproducing kernel Hilbert space, hence capturing topological ... -
Results from the intercalibration of optical low-light calibration sources 2011
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-05-03)Following the 38th Annual European Meeting on Atmospheric Studies by Optical Methods in Siuntio in Finland, an intercalibration workshop for optical low light calibration sources was held in Sodankylä, Finland. The main purpose of this workshop was to provide a comparable scale for absolute measurements of aurora and airglow. All sources brought to the intercalibration workshop were compared to the ... -
Urban land cover classification with missing data modalities using deep convolutional neural networks
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-14)Automatic urban land cover classification is a fundamental problem in remote sensing, e.g., for environmental monitoring. The problem is highly challenging, as classes generally have high interclass and low intraclass variances. Techniques to improve urban land cover classification performance in remote sensing include fusion of data from different sensors with different data modalities. However, ... -
A new method of inferring the size, number density, and charge of mesospheric dust from its in situ collection by the DUSTY probe
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-15)<p>We present a new method of analyzing measurements of mesospheric dust made with DUSTY rocket-borne Faraday cup probes. It can yield the variation in fundamental dust parameters through a mesospheric cloud with an altitude resolution down to 10 cm or less if plasma probes give the plasma density variations with similar height resolution. A DUSTY probe was the first probe that unambiguously detected ... -
Weather situation during observed ship-icing events off the coast of Northern Norway and the Svalbard archipelago
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-19)Ship icing may lead the ship and crew in great jeopardy. Usually, predictions of such ice build-up are based on the modelling of the heat fluxes capable of freezing sea water originated from wave-ship interactions. This study, on the other hand, follows a different and more general approach by investigating the relationship between the weather situation and icing both using observed parameters from ... -
Impact of assimilating sea ice concentration, sea ice thickness and snow depth in a coupled ocean-sea ice modelling system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-08)The accuracy of the initial state is very important for the quality of a forecast, and data assimilation is crucial for obtaining the best-possible initial state. For many years, sea-ice concentration was the only parameter used for assimilation into numerical sea-ice models. Sea-ice concentration can easily be observed by satellites, and satellite observations provide a full Arctic coverage. During ... -
SKIM, a Candidate Satellite Mission Exploring Global Ocean Currents and Waves
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-30)The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the poorly known patterns of divergence and their impact on the ocean heat budget, and monitoring of the emerging Arctic up to 82.5°N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents ... -
Deep Reinforcement Learning for Query-Conditioned Video Summarization
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-21)Query-conditioned video summarization requires to (1) find a diverse set of video shots/frames that are representative for the whole video, and that (2) the selected shots/frames are related to a given query. Thus it can be tailored to different user interests leading to a better personalized summary and differs from the generic video summarization which only focuses on video content. Our work targets ... -
Sparse signal recovery in MIMO specular meteor radars with waveform diversity
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-15)Since the 1950s, specular meteor radars (SMRs) have been used to study the mesosphere and lower thermosphere (MLT) dynamics. Atmospheric parameters derived from SMRs are highly dependent on the number of detected meteors and the accuracy of the meteors' locations. Recently, incoherent and coherent multiple-input-multiple-output (MIMO) radar approaches combined with waveform diversity have been ... -
Investigation of exceptionally radar-dark regions on the lunar nearside
(Conference object; Konferansebidrag, 2019-08)Remote sensing of planetary surfaces is an effective method for gaining knowledge of the processes that shape the planetary bodies in our solar system. This is useful for uncovering the environment of the primordial solar system and to study the current state of the upper crusts of the other planets in our neighborhood. A recent 6-meter wavelength polarimetric radar map of the Moon [?] showed ... -
The Thorpex polar low analysed with AROME-Arctic
(Conference object; Konferansebidrag, 2019-04) -
Observing Mesospheric Turbulence With Specular Meteor Radars: A Novel Method for Estimating Second-Order Statistics of Wind Velocity
(Journal article; Peer reviewed, 2019-07)There are few observational techniques for measuring the distribution of kinetic energy within the mesosphere with a wide range of spatial and temporal scales. <br>This study describes a method for estimating the three‐dimensional mesospheric wind field correlation function from specular meteor trail echoes. Each radar echo provides a measurement of a one‐dimensional projection of the wind velocity ... -
Novel specular meteor radar systems using coherent MIMO techniques to study the mesosphere and lower thermosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-05)Typical specular meteor radars (SMRs) use one transmitting antenna and at least a five-antenna interferometric configuration on reception to study the mesosphere and lower thermosphere (MLT) region. The interferometric configuration allows the measurement of the angle-of-arrival (AOA) of the detected meteor echoes, which in turn is needed to derive atmospheric parameters (e.g., mean winds, momentum ... -
MOSIDEO/CIRFA Tank Experiments on Behavior and Detection of Oil in Ice
(Conference object; Konferansebidrag, 2019-06)In the Arctic, presence of sea ice presents a challenge to safe and sustainable operations. To optimize planning and minimize impact of inadvertent oil spills, oil-in-ice experiments were performed at the HSVA Arctic Environmental Test Basin (AETB) from 14 March to 4 April 2017. Following an under-ice spill and simulated springtime warming, the microscopic movement and distribution of oil in the sea ... -
A low-cost coastal buoy for ice and metocean measurements
(Conference object; Konferansebidrag, 2019-06)Regionally, an ice cover in fjords of mainland Norway may form and break up repeatedly during winter. Due to relatively high water temperatures, the freeze-up process is expected to be related to freshwater-induced stratification in the fjords in conjunction with low air temperatues. In an attempt to identify the variability of water conditions in the fjords leading up to and during ice cover ... -
Radar studies of ionospheric dusty plasma phenomena
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-17)We discuss the influence of charged dust on radar observations in the Earth ionosphere. This region in the upper Earth atmosphere can be described as a partially ionized, low‐temperature plasma. Plasma parameters vary by orders of magnitude spatially and in time. Dust particles influence the charge balance, in some cases dusty plasma condition is met. The polar mesospheric echoes are an example of ... -
Solar Flare Effects on 150-km Echoes Observed Over Jicamarca: WACCM-X Simulations
(Journal article; Tidsskriftartikkel, 2019-09-11)Jicamarca Radio Observatory observations and Whole Atmosphere Community Climate Model with thermosphere‐ionosphere eXtension (WACCM‐X) simulations are used to investigate the effects of the September 7, 2005 X‐17 solar flare on 150‐km echoes, electron densities, and vertical plasma drifts. The solar flare produces a remarkably similar response in the observed 150‐km echoes and simulated electron ...