Viser treff 152-171 av 942

    • Critical echo state network dynamics by means of Fisher information maximization 

      Bianchi, Filippo Maria; Livi, Lorenzo; Jenssen, Robert; Alippi, Cesare (Chapter; Bokkapittel, 2017-07-03)
      The computational capability of an Echo State Network (ESN), expressed in terms of low prediction error and high short-term memory capacity, is maximized on the so-called “edge of criticality”. In this paper we present a novel, unsupervised approach to identify this edge and, accordingly, we determine hyperparameters configuration that maximize network performance. The proposed method is ...
    • Cross-Correlation Between Polarization Channels in SAR Imagery Over Oceanographic Features 

      Brekke, Camilla; Jones, Cathleen; Skrunes, Stine; Holt, Benjamin; Espeseth, Martine; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      This letter discusses cross-correlation features de- rived from near-coincident RADARSAT-2 quad-polarimetric and RISAT-1 hybrid-polarity (HP) measurements collected during the NOrwegian Radar oil Spill Experiment in 2015 (NORSE2015). We show that the imaginary part of the cross-correlation between RH and RV is an HP parallel to the real part of the cross-correlation between HH and VV earlier ...
    • Cross-platform application of a sea ice classification method considering incident angle dependency of backscatter intensity and its use in separating level and deformed ice 

      Guo, Wenkai; Itkin, Polona; Lohse, Johannes; Johansson, Malin; Doulgeris, Anthony Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2021)
      Wide-swath C-band synthetic aperture radar (SAR) has been used for sea ice classification and estimates of sea ice drift and deformation since it first became widely available in the 1990s. Here, we examine the potential to distinguish surface features created by sea ice deformation using ice type classification of SAR data. To perform this task with extended spatial and temporal coverage, we ...
    • Cross-population evaluation of cervical cancer risk prediction algorithms 

      Elvatun, Severin; Knoors, Daan; Nygård, Mari Kiens; Uusküla, Anneli; Võrk, Andres; Nygård, Jan Franz (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-24)
      Background - Cervical cancer is a preventable disease, despite being one of the most common types of female cancers worldwide. Integrating existing programs for cervical cancer screening with personalized risk prediction algorithms can improve population-level cancer prevention by enabling more targeted screening and contrive preventive healthcare innovations. While algorithms developed for cervical ...
    • CryoSat-2 Significant Wave Height in Polar Oceans Derived Using a Semi-Analytical Model of Synthetic Aperture Radar 2011–2019 

      Heorten, Harold; Tsamados, Michel; Armitage, Thomas; Ridout, Andy; Landy, Jack Christopher (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-18)
      This paper documents the retrieval of significant ocean surface wave heights in the Arctic Ocean from CryoSat-2 data. We use a semi-analytical model for an idealised synthetic aperture satellite radar or pulse-limited radar altimeter echo power. We develop a processing methodology that specifically considers both the Synthetic Aperture and Pulse Limited modes of the radar that change close to ...
    • Data Augmentation for SAR Sea Ice and Water Classification Based on Per-Class Backscatter Variation With Incidence Angle 

      WANG, QIANG; Lohse, Johannes; Doulgeris, Anthony Paul; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-03)
      Monitoring sea ice in polar regions is critical for understanding global climate change and supporting marine navigation. Recently, researchers started to utilize machine/deep learning methodologies to automate the separation of sea ice and open water in synthetic aperture radar imagery. However, this requires a large amount of reliably labeled training data. We here propose an augmentation routine ...
    • Data science in wind energy: a case study for Norwegian offshore wind 

      Chen, Hao; Birkelund, Yngve; Zhang, Qixia (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-17)
      In the digital and green transitions, rapidly growing renewable energies are accumulating more and more data. Big data gives room to apply emerging data science to solve challenges in the energy sector. Offshore wind power receives accelerating attention due to its sufficient resources and cleanness. This paper uses data science, including statistical analysis and machine learning, to systematically ...
    • 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 ...
    • A dataset of direct observations of sea ice drift and waves in ice 

      Rabault, Jean; Müller, Malte; Voermans, Joey; Brazhnikov, Dmitry; Turnbull, Ian; Marchenko, Aleksey; Biuw, Martin; Nose, Takehiko; Waseda, Takuji; Johansson, Malin; Breivik, Øyvind; Sutherland, Graig; Hole, Lars Robert; Johnson, Mark; Jensen, Atle; Gundersen, Olav; Kristoffersen, Yngve; Babanin, Alexander; Tedesco, Paulina Souza; Christensen, Kai Håkon; Kristiansen, Martin; Hope, Gaute; Kodaira, Tsubasa; Martins de Aguiar, Victor Cesar; Taelman, Catherine Cecilia A; Quigley, Cornelius Patrick; Filchuk, Kirill; Mahoney, Andrew R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-03)
      Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 ...
    • Dataverktøy til regning, skriving og tegning i naturfag 

      Haugland, Ole Anton (Book; Bok, 2007)
    • Deep divergence-based approach to clustering 

      Kampffmeyer, Michael C.; Løkse, Sigurd; Bianchi, Filippo Maria; Livi, Lorenzo; Salberg, Arnt Børre; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-08)
      A promising direction in deep learning research consists in learning representations and simultaneously discovering cluster structure in unlabeled data by optimizing a discriminative loss function. As opposed to supervised deep learning, this line of research is in its infancy, and how to design and optimize suitable loss functions to train deep neural networks for clustering is still an open question. ...
    • Deep generative models for reject inference in credit scoring 

      Andrade Mancisidor, Rogelio; Kampffmeyer, Michael; Aas, Kjersti; Jenssen, Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)
      Credit scoring models based on accepted applications may be biased and their consequences can have a statistical and economic impact. Reject inference is the process of attempting to infer the creditworthiness status of the rejected applications. Inspired by the promising results of semi-supervised deep generative models, this research develops two novel Bayesian models for reject inference in credit ...
    • Deep Image Translation With an Affinity-Based Change Prior for Unsupervised Multimodal Change Detection 

      Luppino, Luigi Tommaso; Kampffmeyer, Michael; Bianchi, Filippo Maria; Moser, Gabriele; Serpico, Sebastiano Bruno; Jenssen, Robert; Anfinsen, Stian Normann (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-17)
      Image translation with convolutional neural networks has recently been used as an approach to multimodal change detection. Existing approaches train the networks by exploiting supervised information of the change areas, which, however, is not always available. A main challenge in the unsupervised problem setting is to avoid that change pixels affect the learning of the translation function. We propose ...
    • 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; Bokkapittel; Bok; 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. ...
    • A deep learning approach for anomaly identification in PZT sensors using point contact method 

      Kalimullah, Nur M M; Shelke, Amit; Habib, Anowarul (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-21)
      The implementation of piezoelectric sensors is degraded due to surface defects, delamination, and extreme weathering conditions, to mention a few. Hence, the sensor needs to be diagnosed before the efficacious implementation in the structural health monitoring (SHM) framework. To rescue the problem, a novel experimental method based on Coulomb coupling is utilised to visualise the evolution of ...
    • Deep learning architecture “LightOCT” for diagnostic decision support using optical coherence tomography images of biological samples 

      Butola, Ankit; Prasad, Dilip Kumar; Ahmad, Azeem; Dubey, Vishesh Kumar; Qaiser, Darakhshan; Srivastava, Anurag; Senthilkumaran, Paramasivam; Ahluwalia, Balpreet Singh; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-13)
      Optical coherence tomography (OCT) is being increasingly adopted as a label-free and non-invasive technique for biomedical applications such as cancer and ocular disease diagnosis. Diagnostic information for these tissues is manifest in textural and geometric features of the OCT images, which are used by human expertise to interpret and triage. However, it suffers delays due to the long process of ...
    • Deep microlocal reconstruction for limited-angle tomography 

      Andrade-Loarca, Héctor; Kutyniok, Gitta Astrid Hildegard; Öktem, Ozan; Petersen, Philipp (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-04)
      We present a deep-learning-based algorithm to jointly solve a reconstruction problem and a wavefront set extraction problem in tomographic imaging. The algorithm is based on a recently developed digital wavefront set extractor as well as the well-known microlocal canonical relation for the Radon transform. We use the wavefront set information about x-ray data to improve the reconstruction ...
    • 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 ...
    • Deep Semi-Supervised Semantic Segmentation in Multi-Frequency Echosounder Data 

      Choi, Changkyu; Kampffmeyer, Michael; Jenssen, Robert; Handegard, Nils Olav; Salberg, Arnt-Børre (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-01)
      Multi-frequency echosounder data can provide a broad understanding of the underwater environment in a non-invasive manner. The analysis of echosounder data is, hence, a topic of great importance for the marine ecosystem. Semantic segmentation, a deep learning based analysis method predicting the class attribute of each acoustic intensity, has recently been in the spotlight of the fisheries and aquatic ...