Now showing items 61-80 of 393

    • Data-driven detrending of nonstationary fractal time series with echo state networks 

      Maiorino, Enrico; Bianchi, Filippo Maria; Livi, Lorenzo; Rizzi, Antonello; Sadeghian, Alireza (Journal article; Tidsskriftartikkel, 2016-12-14)
      In this paper, we propose a novel data-driven approach for removing trends (detrending) from nonstationary, fractal and multifractal time series. We consider real-valued time series relative to measurements of an underlying dynamical system that evolves through time. We assume that such a dynamical process is predictable to a certain degree by means of a class of recurrent networks called Echo ...
    • Dataverktøy til regning, skriving og tegning i naturfag 

      Haugland, Ole Anton (Book; Bok, 2007)
    • 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 ...
    • Deep kernelized autoencoders 

      Kampffmeyer, Michael C.; Løkse, Sigurd; Bianchi, Filippo Maria; Jenssen, Robert; Livi, Lorenzo (Peer reviewed; Book; Bok; Bokkapittel; Chapter, 2017-05-19)
      In this paper we introduce the deep kernelized autoencoder, a neural network model that allows an explicit approximation of (i) the mapping from an input space to an arbitrary, user-specified kernel space and (ii) the back-projection from such a kernel space to input space. The proposed method is based on traditional autoencoders and is trained through a new unsupervised loss function. ...
    • Deep Reinforcement Learning for Query-Conditioned Video Summarization 

      Zhang, Yujia; Kampffmeyer, Michael C.; Zhao, Xiaoguang; Tan, Min (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 ...
    • Delt situasjonsforståelse under søk og redning i nordområdene 

      Haugstveit, Ida Maria; Skjetne, Jan Håvard; Walderhaug, Ståle; Antonsen, yngve; Ellingsen, May-Britt; Håheim-Saers, Nils; Heggelund, Yngve; Anfinsen, Stian Normann (Research report; Forskningsrapport, 2016-05-03)
      Prosjektets mål er å bidra til økt kunnskap om hvordan etablere delt situasjonsforståelse mellom sentrale aktører innen SAR i Nordområdet. Prosjektgruppa har arbeidet ut ifra en menneske-teknologi-organisasjon (MTO) tilnærming og hvor vi har sett på <br>1) menneskelige og organisatoriske faktorer og <br>2) tekniske faktorer som virker inn på etableringen av delt situasjonsforståelse mellom aktører.<br> ...
    • Derivation of vertical wavelengths of gravity waves in the MLT-region from multispectral airglow observations 

      Schmidt, Carsten; Dunker, Tim; Lichtenstern, Sabrina; Scheer, Jürgen; Wüst, Sabine; Hoppe, Ulf-Peter; Bittner, Michael (Journal article; Tidsskriftartikkel; Peer reviewed; Preprint; Manuskript, 2018-03-06)
      <p>We present the derivation of gravity wave vertical wavelengths from OH airglow observations of different vibrational transitions. It utilizes small phase shifts regularly observed between the OH(3-1) and OH(4-2) intensities in the spectra of the GRIPS (GRound-based Infrared P-branch Spectrometer) instruments, which record the OH airglow emissions in the wavelength range from 1.5  μm to 1.6  μm ...
    • Detection of meteoroid hypervelocity impacts on the Cluster spacecraft: First results 

      Vaverka, Jakub; Pellinen-Wannberg, Asta; Kero, Johan; Mann, Ingrid; De Spiegeleer, Alexandre; Hamrin, Maria; Norberg, Carol; Pitkaenen, Timo (Journal article; Peer reviewed, 2017-06-29)
      We present the first study of dust impact events on one of the Earth‐orbiting Cluster satellites. The events were identified in the measurements of the wide band data (WBD) instrument on board the satellite operating in monopole configuration. Since 2009 the instrument is operating in this configuration due to the loss of three electric probes and is therefore measuring the potential between the ...
    • Determination of the Edge of Criticality in Echo State Networks Through Fisher Information Maximization 

      Bianchi, Filippo Maria; Livi, Lorenzo; Alippi, Cesare (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03)
      It is a widely accepted fact that the computational capability of recurrent neural networks (RNNs) is maximized on the so-called “edge of criticality.” Once the network operates in this configuration, it performs efficiently on a specific application both in terms of: 1) low prediction error and 2) high shortterm memory capacity. Since the behavior of recurrent networks is strongly influenced by the ...
    • Development of the mesospheric Na layer at 69 degrees N during the Geminids meteor shower 2010 

      Dunker, Tim; Hoppe, Ulf-Peter; Stober, Gunter; Rapp, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      The ECOMA sounding rocket campaign in 2010 was performed to investigate the charge state and number density of meteoric smoke particles during the Geminids meteor shower in December 2010. The ALOMAR Na lidar contributed to the campaign with measurements of sodium number density, temperature and line-of-sight wind between 80 and 110 km altitude over Andøya in northern Norway. This paper ...
    • Dielectric microsphere manipulation and chain assembly by counter-propagating waves in a channel waveguide 

      Grujic, Katarina; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
    • Direct Measurement of the Magnitude of the van der Waals Interaction of Single and Multilayer Graphene 

      Chiou, Yu-Cheng; Olukan, Tuza Adeyemi; Almahri, Mariam Ali; Apostoleris, Harry; Chiu, Cheng Hsiang; Lai, Chia-Yun; Lu, Jin-You; Santos, Sergio; Almansouri, Ibraheem; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-23)
      Vertical stacking of monolayers via van der Waals (vdW) assembly is an emerging field that opens promising routes toward engineering physical properties of two-dimensional materials. Industrial exploitation of these engineering heterostructures as robust functional materials still requires bounding their measured properties so as to enhance theoretical tractability and assist in experimental designs. ...
    • Directional features of the downshifted peak observed in HF-induced stimulated electromagnetic emission spectra obtained using an interferometer. 

      Tereshchenko, E.D.; Rietveld, Michael T.; Belyey, Vasyl; Yurik, R.Yu; Brekke, Asgeir; Khudukon, B.Z.; Isham, B.; Hagfors, T.; Grill, M. (Journal article; Peer reviewed; Tidsskriftartikkel, 2006-08-09)
      A high frequency (HF) ionospheric modification experiment was carried out between 25 September and 8 October 2004, using the EISCAT HF transmitter located near Tromsø, Norway. During this experiment the spectra of the stimulated HF sideband waves (stimulated electromagnetic emission or SEE) induced by the HF pump were observed using an interferometer consisting of three spaced receiving antennas ...
    • Discerning the Contribution of Morphology and Chemistry in Wettability Studies 

      Sloyan, Karen; Lai, Chia-Yun; Lu, Jin-You; Alfakes, Boulos; Al Hassan, Saeed; Almansouri, Ibraheem; Dahlem, Marcus S; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-15)
      The wetting behavior of homogeneous systems is now well understood at the macroscopic scale. However, this understanding offers little predictive power regarding wettability when mesoscopic chemical and morphological heterogeneities come into play. The fundamental interest in the effect of heterogeneity on wettability is derived from its high technological relevance in several industries, including ...
    • Does your lab use social media? Sharing three years of experience in science communication 

      Pavlov, Alexey K.; Meyer, Amelie; Rösel, Anja; Cohen, Lana; King, Jennifer; Itkin, Polona; Negrel, Jean; Gerland, Sebastian; Hudson, Stephen R.; Dodd, Paul A.; de Steur, Laura; Mathisen, Stig; Cobbing, Nick; Granskog, Mats A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-27)
      Effective science communication is essential to share knowledge and recruit the next generation of researchers. Science communication to the general public can, however, be hampered by limited resources and a lack of incentives in the academic environment. Various social media platforms have recently emerged, providing free and simple science communication tools to reach the public and young people ...
    • Dust charging and density conditions deduced from observations of PMWE modulated by artificial electron heating 

      Havnes, Ove; La Hoz, Cesar; Rietveld, Michael T; Kassa, Meseret; Baroni, Giovanni; Biebricher, Alexander (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      We present an analysis of relatively strong Polar Mesospheric Winter Echoes (PMWE) under artificial electron heating that changes the PMWE intensity. A major purpose is to find reliable estimates of the relaxation time of the heater modified PMWE to their undisturbed state during the heater switch-off phase; the implications regarding charge/discharge mechanisms; and to exploit the diagnostic potential ...
    • Dust trajectory simulations around Sun, Vega, and Fomalhaut 

      Stamm, Johann Immanuel; Czechowski, Andrzej; Mann, Ingrid; Baumann, Carsten; Myrvang, Margaretha (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-20)
      <p><i>Context - </i>Vega and Fomalhaut display a thermal emission brightness that can possibly arise from hot dust near the stars, an inner extension of their planetary debris disks. There was brought up an idea that nm-sized dust particles are kept in the vicinity of the stars by electromagnetic forces. This resembles the trapping that model calculations show in the corotating magnetic field in the ...
    • Dynamic rayed aurora and enhanced ion-acoustic radar echoes 

      Ivchenko, N.; Blixt, Erik Mårten; Grydeland, Tom; Hagfors, T.; Trondsen, T.S.; La Hoz, Cesar; Lanchester, B.S.; Løvhaug, Unni Pia (Journal article; Peer reviewed; Tidsskriftartikkel, 2005-01-31)
      The generation mechanism for naturally enhanced ion-acoustic echoes is still debated. One important issue is how these enhancements are related to auroral activity. All events of enhanced ion-acoustic echoes observed simultaneously with the EISCAT Svalbard Radar (ESR) and with high-resolution narrow field-of-view auroral imagers have been collected and studied. Characteristic of all the ...
    • Dynamics of Dust Particles near Sun, Vega and Fomalhaut 

      Stamm, Johann Immanuel; Baumann, Carsten; Czechowski, Andrzej; Mann, Ingrid; Myrvang, Margaretha (Conference object; Konferansebidrag, 2018)
    • Dynamics of nanodust particles emitted from elongated initial orbits 

      Czechowski, Andrzej; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2018)
      <p><i>Context</i>: Because of high charge-to-mass ratio, the nanodust dynamics near the Sun is determined by interplay between the gravity and the electromagnetic forces. Depending on the point where it was created, a nanodust particle can either be trapped in a non-Keplerian orbit, or escape away from the Sun, reaching large velocity. The main source of nanodust is collisional fragmentation of ...