Blar i tittel Artikler, rapporter og annet (fysikk og teknologi)

Viser treff 725-744 av 942

    • Sampling moiré method: a tool for sensing quadratic phase distortion and its correction for accurate quantitative phase microscopy 

      Jayakumar, Nikhil; Ahmad, Azeem; Mehta, Dalip Singh; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-24)
      The advantages of quantitative phase microscopy (QPM) such as label-free imaging with high spatial sensitivity, live cell compatibility and high-speed imaging makes it viable for various biological applications. The measurement accuracy of QPM strongly relies on the shape of the recorded interferograms, whether straight or curved fringes are recorded during the data acquisition. Moreover, for a ...

    • SAR and Passive Microwave Fusion Scheme: A Test Case on Sentinel-1/AMSR-2 for Sea Ice Classification 

      Khachatrian, Eduard; Dierking, Wolfgang; Chlaily, Saloua; Eltoft, Torbjørn; Dinessen, Frode; Hughes, Nick; Marinoni, Andrea (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)
      The most common source of information about sea ice conditions is remote sensing data, especially images obtained from synthetic aperture radar (SAR) and passive microwave radiometers (PMR). Here we introduce an adaptive fusion scheme based on Graph Laplacians that allows us to retrieve the most relevant information from satellite images. In a first test case, we explore the potential of sea ice ...

    • Satellittovervåking av isdrift i Arktis 

      Kræmer, Thomas (Conference object; Konferansebidrag, 2013)

    • Scalable-resolution structured illumination microscopy 

      Butola, Ankit; Acuna Maldonado, Sebastian Andres; Hansen, Daniel Henry; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-15)
      Structured illumination microscopy suffers from the need of sophisticated instrumentation and precise calibration. This makes structured illumination microscopes costly and skill-dependent. We present a novel approach to realize super-resolution structured illumination microscopy using an alignment non-critical illumination system and a reconstruction algorithm that does not need illumination ...

    • Scale-free vortex cascade emerging from random forcing in a strongly coupled system 

      Rypdal, Kristoffer; Ratynskaia, Svetlana; Kozelov, Boris; Klumov, Boris; Knapek, Christina (Working paper; Arbeidsnotat, 2008-03-04)
      The notions of self-organised criticality (SOC) and turbulence are traditionally considered to be applicable to disjoint classes of phenomena. Nevertheless, scale-free burst statistics is a feature shared by turbulent as well as self-organised critical dynamics. It has also been suggested that another shared feature is universal non-gaussian probability density functions (PDFs) of global fluctuations. ...

    • Scanning acoustic microscopy—A novel noninvasive method to determine tumor interstitial fluid pressure in a xenograft tumor model 

      Hofmann, Matthias; Pflanzer, Ralph; Habib, Anowarul; Shelke, Amit; Bereiter-Hahn, Jürgen; Bernd, August; Kaufmann, Roland; Sader, Robert; Kippenberger, Stefan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-22)
      Elevated tumor interstitial fluid pressure (TIFP) is a prominent feature of solid tumors and hampers the transmigration of therapeutic macromolecules, for example, large monoclonal antibodies, from tumor-supplying vessels into the tumor interstitium. TIFP values of up to 40 mm Hg have been measured in experimental solid tumors using two conventional invasive techniques: the wick-in-needle and the ...

    • A Scatter-Based Prototype Framework and Multi-Class Extension of Support Vector Machines 

      Jenssen, Robert; Kloft, Marius; Zien, Alexander; Sonnenburg, Soeren; Müller, Klaus R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      We provide a novel interpretation of the dual of support vector machines (SVMs) in terms of scatter with respect to class prototypes and their mean. As a key contribution, we extend this framework to multiple classes, providing a new joint Scatter SVM algorithm, at the level of its binary counterpart in the number of optimization variables. This enables us to implement computationally efficient ...

    • Scenario-based modelling of the potential for solar energy charging of electric vehicles in two Scandinavian cities 

      Good, Clara; Shepero, Mahmoud; Munkhammar, Joakim; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-19)
      In order to contribute to the reduction of greenhouse gas emissions, electric vehicles (EVs) should be charged using electricity from renewable energy sources. This paper describes a study of photovoltaics (PV) utilization for EV charging in two Scandinavian cities: Tromsø in Norway and Uppsala in Sweden, with the objective to evaluate self-sufficiency and self-consumption. The suitable areas ...

    • The science case for the EISCAT_3D radar 

      McCrea, Ian W.; Aikio, Anita; Alfonsi, Lucilla; Belova, Evgenia; Buchert, Stephan C.; Clilverd, Mark; Engler, Norbert; Gustavsson, Björn Johan; Heinselman, C.; Kero, Johan; Kosch, Mike; Lamy, Herve; Leyser, Thomas; Ogawa, Yasunobu; Oksavik, Kjellmar; Pellinen-Wannberg, Asta; Pitout, Frederic; Rapp, Markus; Stanislawska, Iwona; Vierinen, Juha (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-29)
      The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed ...

    • Science goals for a high-frequency radar and radio imaging array 

      Isham, Brett Cameron; Bullett, Terence; Gustavsson, Björn Johan; Polisensky, Emil; Brum, Christiano; Fallen, Christopher; Belyey, Vasyl; Parra-Rojas, Francisco; Norouzi, Leila; Stramkals, Arturs; Ökten, Mehmet Baran (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-01)
      A medium and high-frequency antenna array for radar and radio imaging of the ionosphere is planned for installation in Aguadilla, Puerto Rico. Science goals include the study of space weather, radio propagation, meteors, lightning, and plasma physics. Radio imaging is ideal for the study of stimulated ionospheric radio emissions, such as those induced by the Arecibo Observatory high-power HF radio ...

    • The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets 

      Jones, Geraint; Knight, Matthew; Battams, Karl; Boice, Daniel; Brown, John; Giordano, Silvio; Raymond, John; Snodgrass, Colin; Steckloff, Jordan; Weissman, Paul; Fitzsimmons, Alan; Lisse, Carey M; Opitom, Cyrielle; Birkett, Kimberley; Bzowski, Maciej; Decock, Alice; Mann, Ingrid; Ramanjooloo, Yudish; McCauley, Patrick (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-18)
      This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other ...

    • Scrape-off layer turbulence in TCV: Evidence in support of stochastic modelling. 

      Theodorsen, Audun; Garcia, Odd Erik; Horacek, Jan; Kube, Ralph; Pitts, RA (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-28)
      Intermittent fluctuations in the TCV scrape-off layer have been investigated by analysing long Langmuir probe data time series under stationary conditions, allowing calculation of fluctuation statistics with high accuracy. The ion saturation current signal is dominated by the frequent occurrence of large-amplitude bursts attributed to filament structures moving through the scrape-off layer. The ...

    • Sea Ice Classification of SAR Imagery Based on Convolution Neural Networks 

      Khaleghian, Salman; Ullah, Habib; Kræmer, Thomas; Hughes, Nick; Eltoft, Torbjørn; Marinoni, Andrea (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-29)
      We explore new and existing convolutional neural network (CNN) architectures for sea ice classification using Sentinel-1 (S1) synthetic aperture radar (SAR) data by investigating two key challenges: binary sea ice versus open-water classification, and a multi-class sea ice type classification. The analysis of sea ice in SAR images is challenging because of the thermal noise effects and ambiguities ...

    • Sea ice classification of TerraSAR-X ScanSAR images for the MOSAiC expedition incorporating per-class incidence angle dependency of image texture 

      Guo, Wenkai; Itkin, Polona; Singha, Suman; Doulgeris, Anthony Paul; Johansson, Malin; Spreen, Gunnar (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-16)
      We provide sea ice classification maps of a subweekly time series of single (horizontal–horizontal, HH) polarization X-band TerraSAR-X scanning synthetic aperture radar (TSX SC) images from November 2019 to March 2020, covering the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. This classified time series benefits from the wide spatial coverage ...

    • Sea ice local surface topography from single-pass satellite InSAR measurements: A feasibility study 

      Dierking, Wolfgang Fritz Otto; Lang, Oliver; Busche, Thomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-29)
      Quantitative parameters characterizing the sea ice surface topography are needed in geophysical investigations such as studies on atmosphere–ice interactions or sea ice mechanics. Recently, the use of space-borne single-pass interferometric synthetic aperture radar (InSAR) for retrieving the ice surface topography has attracted notice among geophysicists. In this paper the potential of InSAR ...

    • Sea Ice Remote Sensing—Recent Developments in Methods and Climate Data Sets 

      Sandven, Stein; Spreen, Gunnar; Heygster, Georg; Girard-Ardhuin, Fanny; Farrell, Sinéad L.; Dierking, Wolfgang Fritz Otto; Allard, Richard A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-03)
      Sea ice monitoring by polar orbiting satellites has been developed over more than four decades and is today one of the most well-established applications of space observations. This article gives an overview of data product development from the first sensors to the state-of-the-art regarding retrieval methods, new products and operational data sets serving climate monitoring as well as daily operational ...

    • Sea ice segmentation using Tandem-X pursuit mono static and alternative bistatic modes 

      Yitayew, Temesgen Gebrie; Doulgeris, Anthony Paul; Eltoft, Torbjørn; Dierking, Wolfgang Fritz Otto; Brekke, Camilla; Rösel, Anja (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-04)
      In this paper we investigate interferometric pairs of SAR images acquired by Tandem-X with the monostatic pursuit and the alternative bistatic modes for sea ice segmentation. The individual SAR images are modelled as non-Gaussian, and from the modelled data different features are extracted, stacked together and clustered. The interferometric coherence is regarded as an additional feature and utilized ...

    • Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70 N, modelled tides (GSWM, CMAM) 

      Hall, Chris; Manson, A.H.; Meek, C.; Hagan, M.; Koshyk, J.; Franke, S.; Fritts, D.; Hocking, W.; Igarashi, K.; MacDougall, J.; Riggin, D.; Vincent, R. (Journal article; Peer reviewed; Tidsskriftartikkel, 2002)
      In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the equator and high northern latitudes: Christmas Island (2° N), Hawaii (22° N), Urbana (40° N), London (43° N), Saskatoon (52° N) and Tromsø (70° N). Common harmonic analysis was applied, ...

    • Secondary charging effects due to icy dust particle impacts on rocket payloads 

      Bekele, Meseret Kassa; Rapp, M.; Hartquist, T W; Havnes, Ove (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      We report measurements of dust currents obtained with a small probe and a larger probe during the flight of the ECOMA-4 rocket through the summer polar mesosphere. The payload included two small dust probes behind a larger dust probe located centrally at the front. For certain phases of the payload rotation, the current registered by one of the small dust probes was up to 2 times the current measured ...

    • A Segmentation based CFAR detection algorithm using truncated statistics 

      Ding, Tao; Doulgeris, Anthony Paul; Brekke, Camilla (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-18)
      Target detection in nonhomogeneous sea clutter environments is a complex and challenging task due to the capture effect from interfering outliers and the clutter edge effect from background intensity transitions. For synthetic aperture radar (SAR) measurements, those issues are commonly caused by multiple targets and meteorological and oceanographic phenomena, respectively. This paper proposes a ...