Recent additions

  • Power-law scaling of uncorrelated plasma bursts 

    Theodorsen, Audun; Garcia, Odd Erik; Rypdal, Martin wibe (Conference object; Konferansebidrag, 2019-07)
  • Synthetic Aperture Radar Remote Sensing of Operational Platform Produced Water Releases 

    Skrunes, Stine; Johansson, Malin; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-03)
    Oil spill detection services based on satellite synthetic aperture radar (SAR) frequently detect oil slicks close to platforms due to legal releases of produced water. Separating these slicks from larger releases, e.g., due to accidental leakage is challenging. The aim of this work is to investigate the SAR characteristics of produced water, including the typical appearance in HH/VV data, possible ...
  • Separation and characterisation of mineral oil slicks and newly formed sea ice in L-band synthetic aperture radar 

    Johansson, Malin; Espeseth, Martine; Brekke, Camilla; Skrunes, Stine (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)
    Maritime activities in the Arctic Ocean is increasing and consequently the risk for an oil spill there is rising. Synthetic Aperture Radar (SAR) is used operationally to detect and monitor oil slicks and for sea ice monitoring and observations. Leads are often used for ship routing and within the leads newly formed sea ice is often present. Separation between the low backscatter areas that constitutes ...
  • Towards operational sea ice type retrieval using L-band Synthetic aperture radar 

    Singha, Suman; Johansson, Malin; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)
    Operational ice services around the world have recognized the economic and environmental benefits that come from the increased capabilities and uses of space-borne Synthetic Aperture Radar (SAR) observation system. The two major objectives in SAR based remote sensing of sea ice is on the one hand to have a large areal coverage, and on the other hand to obtain a radar response that carries as much ...
  • The Impact of Additive Noise on Polarimetric RADARSAT-2 Data Covering Oil Slicks 

    Espeseth, Martine; Skrunes, Stine; Brekke, Camilla; Johansson, Malin (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)
    We attempt to understand how a set of well known polari-metric Synthetic Aperture Radar (SAR) features are impacted by the additive system noise for mineral oil and produced water slicks. For this, we use quad-polarimetric SAR scenes from Radarsat-2. Oil slicks at sea can be detected using SAR instruments, and the dual- (HH-VV) and quad-polarimetric modes can provide additional information about the ...
  • Measurement of inner wall limiter SOL widths in KSTAR tokamak 

    Bak, J. G.; Pitts, RA; Kim, HS; Lee, H; Bin, C.; Juhn, JW; Hong, SH; Garcia, Odd Erik; Kube, Ralph Arthur; Seo, DC (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-27)
    Scrape-off layer (SOL) widths <i>λ<sub>q</sub></i> are presented from the KSTAR tokamak using fast reciprocating Langmuir probe assembly (FRLPA) measurements at the outboard mid-plane (OMP) and the infra-Red (IR) thermography at inboard limiter tiles in moderately elongated (<i>κ</i> = 1.45 – 1.55) L-mode inner wall-limited (IWL) plasmas under experimental conditions such as B<sub>T</sub> = 2.0 T, ...
  • SOL width and intermittent fluctuations in KSTAR 

    Garcia, Odd Erik; Kube, Ralph Arthur; Theodorsen, Audun; Bak, J. G.; Hong, SH; Kim, H.S.; KSTAR, project team; Pitts, RA (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-27)
    Radial profiles of the ion saturation current and its fluctuation statistics are presented from probe measurements in L-mode, neutral beam heated plasmas at the outboard mid-plane region of KSTAR. The results are consistent with the familiar two-layer structure, seen elsewhere in tokamak L-mode discharges, with a steep near-SOL profile and a broad far-SOL profile. The profile scale length in the ...
  • One-Year Analysis of Dust Impact-Like Events Onto the MMS Spacecraft 

    Vaverka, Jakub; Pavlu, Jiri; Nouzak, Libor; Safrankova, Jana; Nemecek, Zdenek; Mann, Ingrid; Ye, Shengyi; Lindqvist, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-16)
    We present an analysis of 1‐year data of dust impacts observed on two of the Earth‐orbiting Magnetospheric Multiscale mission (MMS) spacecraft. The dust impact signals were identified in observations of the electric field probes and were registered simultaneously by monopole and dipole configurations of the instrument. This unique setup allows us to reliably identify changes in the spacecraft potential ...
  • Winter storms accelerate the demise of sea ice in the Atlantic sector of the Arctic Ocean 

    Graham, Robert M.; Itkin, Polona; Meyer, Amelie; Sundfjord, Arild; Spreen, Gunnar; Smedsrud, Lars H.; Liston, Glen E.; Cheng, Bin; Cohen, Lana; Divine, Dmitry; Fer, Ilker; Fransson, Agneta; Gerland, Sebastian; Haapala, Jari; Hudson, Stephen R.; Johansson, Malin; King, Jennifer A.; Merkouriadi, Ioanna; Peterson, Algot Kristoffer; Provost, Christine; Randelhoff, Achim; Rinke, Annette; Rösel, Anja; Sennechael, Nathalie; Walden, Von P.; Duarte, Pedro; Assmy, Philipp; Steen, Harald; Granskog, Mats A. (Journal article; Peer reviewed, 2019-06-25)
    A large retreat of sea-ice in the ‘stormy’ Atlantic Sector of the Arctic Ocean has become evident through a series of record minima for the winter maximum sea-ice extent since 2015. Results from the Norwegian young sea ICE (N-ICE2015) expedition, a five-month-long (Jan-Jun) drifting ice station in first and second year pack-ice north of Svalbard, showcase how sea-ice in this region is frequently ...
  • Authenticating the presence of a relativistic massive black hole binary in OJ 287 using its general relativity centenary flare: Improved orbital parameters 

    Dey, Lankeswar; Valtonen, MJ; Gopakumar, A; Zola, S; Hudec, R; Pihajoki, P; Ciprini, S; Matsumoto, K; Sadakane, K; Kidger, M; Nilsson, K; Mikkola, S; Sillanpää, A; Takalo, LO; Lehto, HJ; Berdyugin, A; Piirola, V; Jermak, H; Baliyan, KS; Pursimo, T; Caton, DB; Alicavus, F; Baransky, A; Blay, P; Boumis, P; Boyd, D; Campas Torrent, M; Campos, F; Carrillo Goméz, J; Chandra, S; Chavushyan, V; Dalessio, J; Debski, B; Drozdz, M; Er, H; Erdem, A; Escartin Pérez, A; Fallah Ramazani, V; Filippenko, AV; Gafton, E; Ganesh, S; Garcia, F; Gazeas, K; Godunova, V; Goméz Pinilla, F; Gopinathan, M; Haislip, JB; Harmanen, J; Hurst, G; Janik, J; Jelinek, M; Joshi, A; Kagitani, M; Karjalainen, R; Kaur, N; Keel, WC; Kouprianov, VV; Kundera, T; Kurowski, S; Kvammen, Andreas; Lacluyze, AP; Lee, BC; Liakos, A; Lindfors, E; Lozano de Haro, J; Mugrauer, M; Naves Nogues, R; Neely, AW; Nelson, RH; Ogloza, W; Okano, S; Pajdosz-Śmierciak, U; Pandey, JC; Perri, M; Poyner, G; Provencal, J; Raj, A; Reichart, DE; Reinthal, R; Reynolds, T; Saario, J; Sadegi, S; Sakanoi, T; Salto González, J-L; Sameer, S; Schweyer, T; Simon, A; Siwak, M; Soldán Alfaro, FC; Sonbas, E; Steele, I; Stocke, JT; Strobl, J; Tomov, T; Tremosa Espasa, L; Valdes, JR; Perez, J Valero; Verrecchia, F; Webb, JR; Yoneda, M; Zejmo, M; Zheng, W; Zielinski, P (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-05)
    Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects ...
  • Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR 

    Zucca, P; Morosan, D; Rouillard, A; Fallows, Richard; Gallagher, P. T.; Magdalenic, J; Klein, K-L; Mann, G; Vocks, C; Carley, E. P.; Bisi, M. M.; Kontar, E. P.; Rothkaehl, Hanna; Dabrowski, B; Krankowski, A; Anderson, James; Asgekar, A; Bell, M. E.; Bentum, M. J.; Best, P; Blaauw, R; Breitling, F.; Broderick, J. W.; Brouw, W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Garrett, M. A.; Grießmeier, J. M.; Gunst, A. W.; Heald, G.; Hoeft, M.; Hörandel, J.; Iacobelli, M.; Juette, E; Karastergiou, A.; van Leeuwen, J.; McKay, Derek; Mulder, H.A.; Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey, V. N.; Pekal, R.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rowlinson, A.; Schwarz, D. J.; Shulevski, A.; Sluman, J.; Smirnov, O.V.; Sobey, C.; Soida, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; van Weeran, R. J.; Wucknitz, O.; Zarka, P. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-19)
    <p><i>Context - </i>Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with coronal mass ejections (CMEs) and reach speeds higher than the local magnetosonic speed. Radio imaging of decameter wavelengths (20–90 MHz) is now possible with the Low Frequency Array ...
  • Classification of Micro-Damage in Piezoelectric Ceramics Using Machine Learning of Ultrasound Signals 

    Tripathi, Gaurav; Anowarul, Habib; Agarwal, Krishna; Prasad, Dilip K. (Journal article; Peer reviewed, 2019-09-28)
    Ultrasound based structural health monitoring of piezoelectric material is challenging if a damage changes at a microscale over time. Classifying geometrically similar damages with a difference in diameter as small as 100 m is difficult using conventional sensing and signal analysis approaches. Here, we use an unconventional ultrasound sensing approach that collects information of the entire ...
  • Multi-scale measurements of mesospheric aerosols and electrons during the MAXIDUSTY campaign 

    Antonsen, Tarjei; Havnes, Ove; Spicher, Andres (Journal article; Peer reviewed, 2019-04-08)
    We present in situ measurements of small-scale fluctuations in aerosol populations as recorded through a mesospheric cloud system from the Faraday cups DUSTY and MUDD during on the MAXIDUSTY-1 and 1B sounding rocket payloads launched in the summer of 2016. <br>Two mechanically identical DUSTY probes mounted with an inter-spacing of ∼10 cm recorded very different currents, with strong spin modulation, ...
  • Gaussian Process Sensitivity Analysis for Oceanic Chlorophyll Estimation 

    Blix, Katalin; Camps-Valls, Gustau; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-04)
    Gaussian process regression (GPR) has experienced tremendous success in biophysical parameter retrieval in the past years. The GPR provides a full posterior predictive distribution so one can derive mean and variance predictive estimates, i.e., point-wise predictions and associated confidence intervals. GPR typically uses translation invariant covariances that make the prediction function very ...
  • Wind power predictions in complex terrain using analog ensembles 

    Birkelund, Yngve; Alessandrini, Stefano; Byrkjedal, Øyvind; Monache, Luca Delle (Journal article; Tidsskriftartikkel, 2018)
  • Unsupervised domain adaptation for automatic estimation of cardiothoracic ratio 

    Dong, Nanqing; Kampffmeyer, Michael C.; Liang, Xiaodan; Wang, Zeya; Dai, Wei; Xing, Eric P. (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 

    Bianchi, Filippo Maria; Livi, Lorenzo; Ferrante, Alberto; Milosevic, Jelena; Miroslaw, Malek (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 

    Kampffmeyer, Michael C.; Løkse, Sigurd; Bianchi, Filippo Maria; Jenssen, Robert; Livi, Lorenzo (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 

    Brändström, B. Urban E.; Enell, Carl-Fredrik; Widell, Ola; Hansson, Thord; Whiter, Daniel; Mäkinen, Sanna; Mikhaylova, Daria; Axelsson, Katarina; Sigernes, Fred; Gulbrandsen, Njål; Schlatter, Nicola M.; Gjendem, Amund Gjerde; Cai, L.; Reistad, Jone Peter; Daae, Marianne; Demissie, Teferi Dejene; Andalsvik, Yngvild Linnea; Roberts, Owen; Poluyanov, Stepan Viktorovich; Chernouss, Sergey (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 

    Kampffmeyer, Michael C.; Salberg, Arnt Børre; Jenssen, Robert (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, ...

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