Now showing items 765-784 of 942

    • Signature of Arctic first-year ice melt pond fraction in X-band SAR imagery 

      Fors, Ane Schwenke; Divine, Dmitry V; Doulgeris, Anthony Paul; Renner, Angelika; Gerland, Sebastian (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-23)
      In this paper we investigate the potential of melt pond fraction retrieval from X-band polarimetric synthetic aperture radar (SAR) on drifting first-year sea ice. Melt pond fractions retrieved from a helicopter-borne camera system were compared to polarimetric features extracted from four dual-polarimetric X-band SAR scenes, revealing significant relationships. The correlations were strongly dependent ...
    • Significant ionospheric hole and equatorial plasma bubbles after the 2022 Tonga volcano eruption 

      Aa, Ercha; Zhang, Shunrong; Erickson, Philip J.; Vierinen, Juha; Coster, Anthea J.; Goncharenko, Larisa P.; Spicher, Andres; Rideout, William (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-28)
      This paper investigates the local and global ionospheric responses to the 2022 Tonga volcano eruption, using ground-based Global Navigation Satellite System total electron content (TEC), Swarm in situ plasma density measurements, the Ionospheric Connection Explorer (ICON) Ion Velocity Meter (IVM) data, and ionosonde measurements. The main results are as follows: (a) A significant local ionospheric ...
    • Silicon nitride waveguide platform for fluorescence microscopy of living cells 

      Tinguely, Jean-Claude; Helle, Øystein Ivar; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      Waveguide chip-based microscopy reduces the complexity of total internal reflection fluorescence (TIRF) microscopy, and adds features like large field of view illumination, decoupling of illumination and collection path and easy multimodal imaging. However, for the technique to become widespread there is a need of low-loss and affordable waveguides made of high-refractive index material. Here, ...
    • Silicon substrate significantly alters dipole-dipole resolution in coherent microscope 

      Liu, Zicheng; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-16)
      Considering a coherent microscopy setup, influences of the substrate below the sample in the imaging performances are studied, with a focus on high refractive index substrate such as silicon. Analytical expression of 3D full-wave vectorial point spread function, i.e. the dyadic Green's function is derived for the optical setup together with the substrate. Numerical analysis are performed in order ...
    • A Simple and Extendable Segmentation Method for Multi-Polarisation SAR Images 

      Doulgeris, Anthony Paul (Conference object; Konferansebidrag, 2013)
      This work presents a simple feature-based multi-channel SAR segmentation method that produces good, smooth, fast and robust results for image segmentation and interpretation. A basic set of six features produce good class distinction for general applications, and the method is easily extendable with new features and for multi-source data fusion. Optional steps of sub-sampling and Markov Random ...
    • Simulation of Anti-reflection Coated Carbonaceous Spectrally Selective Absorbers 

      Chen, Zhonghua; Amitap, Jain; Boström, Tobias (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-11-22)
    • Simultaneous electrochemical determination of benzenediol compounds in environmental samples using nano architectures of hydrogen ammonium zinc molybdate layered double hydroxides integrated with carbon black modified electrode 

      Karuppiah, Chelladurai; Babulal, Sivakumar Musuvadhi; Chen, Shen-Ming; Palanisamy, Selvakumar; Hsu, Li-Fan; Yang, Chun-Chen; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-02)
      Phenolic compounds, such as benzenediol (BD), are toxic and exhibit poor biodegradability, posing a threat to human health and the environment, even at low concentrations. Therefore, the simultaneous detection of BD at low detection limits and a wide detection range is of significant interest for monitoring water quality and environmental remediation efforts. In this study, we developed a novel ...
    • Simultaneous Global Ionospheric Disturbances Associated With Penetration Electric Fields During Intense and Minor Solar and Geomagnetic Disturbances 

      Zhang, Shun-Rong; Nishimura, Yukitoshi; Vierinen, Juha-Pekka; Lyons, Larry R.; Knipp, Delores J.; Gustavsson, Björn Johan; Waghule, Bhagyashree V.; Erickson, Philip J.; Coster, Anthea J.; Aa, Ercha; Spicher, Andres (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)
      A new observational phenomenon, named Simultaneous Global Ionospheric Density Disturbance (SGD), is identified in GNSS total electron content (TEC) data during periods of three typical geospace disturbances: a Coronal Mass Ejection-driven severe disturbance event, a high-speed stream event, and a minor disturbance day with a maximum Kp of 4. SGDs occur frequently on dayside and dawn sectors, with ...
    • Simultaneous observations of a Mesospheric Inversion Layer and turbulence during the ECOMA-2010 rocket campaign 

      Szewczyk, Artur; Strelnikov, Boris; Rapp, Markus; Strelnikova, Irina; Baumgarten, Gerd; Kaifler, Natalie; Dunker, Tim; Hoppe, Ulf-Peter (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      From 19 November to 19 December 2010 the fourth and final ECOMA rocket campaign was conducted at Andøya Rocket Range (69 N, 16 E) in northern Norway. We present and discuss measurement results obtained during the last rocket launch labelled ECOMA09 when simultaneous and true common volume in situ measurements of temperature and turbulence supported by ground-based lidar observations reveal ...
    • Single-input and multiple-output surface acoustic wave sensing for damage quantification in piezoelectric sensors 

      Pamwani, Lavish; Habib, Anowarul; Melandsø, Frank; Ahluwalia, Balpreet Singh; Shelke, Amit (Journal article; Peer reviewed, 2018-06-22)
      The main aim of the paper is damage detection at the microscale in the anisotropic piezoelectric sensors using surface acoustic waves (SAWs). A novel technique based on the single input and multiple output of Rayleigh waves is proposed to detect the microscale cracks/flaws in the sensor. A convex-shaped interdigital transducer is fabricated for excitation of divergent SAWs in the sensor. An angularly ...
    • Single-mode limit and bending losses for shallow Rib Si3N4 waveguides 

      Dullo, Firehun Tsige; Tinguely, Jean-Claude; Solbø, Stian; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-07)
      The single-mode limit and bending losses for shallow rib waveguides are studied using the full vectorial film mode matching method. The maximum rib height for single-mode waveguides is found to be on the order of 10 nm for a rib width of 2 m and a wavelength of 785 nm, with the exact value depending on the core thickness and the polarization. Bending losses are calculated as a function of several ...
    • Single-Molecule Sizing through Nanocavity Confinement 

      Jacquat, Raphaël P. B.; Krainer, Georg; Peter, Quentin A. E.; Babar, Ali Nawaz; Vanderpoorten, Oliver; Xu, Catherine K.; Welsh, Timothy J.; Kaminski, Clemens F.; Keyser, Ulrich F.; Baumberg, Jeremy J.; Knowles, Tuomas P. J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24)
      : An approach relying on nanocavity confinement is developed in this paper for the sizing of nanoscale particles and single biomolecules in solution. The approach, termed nanocavity diffusional sizing (NDS), measures particle residence times within nanofluidic cavities to determine their hydrodynamic radii. Using theoretical modeling and simulations, we show that the residence time of particles ...
    • Single-shot fringe pattern phase retrieval using improved period-guided bidimensional empirical mode decomposition and Hilbert transform 

      Gocłowski, Paweł; Cywinska, Maria; Ahmad, Azeem; Ahluwalia, Balpreet Singh; Trusiak, Maciej (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-17)
      Fringe pattern analysis is the central aspect of numerous optical measurement methods, e.g., interferometry, fringe projection, digital holography, quantitative phase microscopy. Experimental fringe patterns always contain significant features originating from fluctuating environment, optical system and illumination quality, and the sample itself that severely affect analysis outcome. Before the ...
    • Single-shot multispectral quantitative phase imaging of biological samples using deep learning 

      Bhatt, Sunil; Butola, Ankit; Kumar, Anand; Thapa, Pramila; Joshi, Akshay; Jadhav, Suyog S.; Singh, Neetu; Prasad, Dilip K.; Agarwal, Krishna; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-16)
      Multispectral quantitative phase imaging (MS-QPI) is a high-contrast label-free technique for morphological imaging of the specimens. The aim of the present study is to extract spectral dependent quantitative information in single-shot using a highly spatially sensitive digital holographic microscope assisted by a deep neural network. There are three different wavelengths used in our method: 𝜆=532 , ...
    • Skewed Lorentzian pulses and exponential frequency power spectra 

      Garcia, Odd Erik; Theodorsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-18)
      Frequency power spectra due to a super-position of uncorrelated Lorentzian pulses with a random distribution of amplitudes are considered. For pulses with a constant duration, there is an exponential frequency spectrum which is independent of the degree of pulse overlap and the pulse amplitude distribution. The spectrum is furthermore shown to be unaffected by skewness of the Lorentzian pulses and ...
    • SKIM, a Candidate Satellite Mission Exploring Global Ocean Currents and Waves 

      Ardhuin, Fabrice; Brandt, Peter; Gaultier, Lucile; Donlon, Craig James; Battaglia, Alessandro; Boy, Francois; Casal, Tania; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean-Marc; De Witte, Erik; Dibarboure, Gerald; Engen, Geir; Johnsen, Harald; Lique, Camille; López-Dekker, Paco; Maes, Christophe; Martin, Adrien; Marie, Louis; Menemenlis, Dimitris; Nouguier, Frederic; Peureux, Charles; Rampal, Pierre; Ressler, Gerhard; Rio, Marie-Helene; Rommen, Bjorn; Shutler, Jamie D.; Suess, Martin; Tsamados, Michel; Ubelmann, Clement; van Sebille, Erik; van den Oever, Martin; Stammer, Detlef (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 ...
    • Snow and Ice Thickness Retrievals Using GNSS-R: Preliminary Results of the MOSAiC Experiment 

      Munoz-Martin, Joan Francesc; Perez, Adrian; Camps, Adriano; Ribó, Serni; Cardellach, Estel; Stroeve, Julienne; Nandan, Vishnu; Itkin, Polona; Tonboe, Rasmus; Hendricks, Stefan; Huntemann, Marcus; Spreen, Gunnar; Pastena, Massimiliano (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)
      The FSSCat mission was the 2017 ESA Sentinel Small Satellite (S⌃3) Challenge winner and the Copernicus Masters competition overall winner. It was successfully launched on 3 September 2020 onboard the VEGA SSMS PoC (VV16). FSSCat aims to provide coarse and downscaled soil moisture data and over polar regions, sea ice cover, and coarse resolution ice thickness using a combined L-band microwave radiometer ...
    • Snowfall and snow accumulation during the MOSAiC winter and spring seasons 

      Wagner, David N.; Shupe, Matthew D.; Cox, Christopher; Persson, Ola G.; Uttal, Taneil; Frey, Markus M.; Kirchgaessner, Amélie; Schneebeli, Martin; Jaggi, Matthias; MacFarlane, Amy R.; Itkin, Polona; Arndt, Stefanie; Hendricks, Stefan; Krampe, Daniela; Nicolaus, Marcel; Ricker, Robert; Regnery, Julia; Kolabutin, Nikolai; Shimanshuck, Egor; Oggier, Marc; Raphael, Ian; Stroeve, Julienne; Lehning, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-17)
      Data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition allowed us to investigate the temporal dynamics of snowfall, snow accumulation and erosion in great detail for almost the whole accumulation season (November 2019 to May 2020). We computed cumulative snow water equivalent (SWE) over the sea ice based on snow depth and density retrievals from a ...
    • Soft thresholding schemes for multiple signal classification algorithm 

      Acuña Maldonado, Sebastian Andres; Opstad, Ida Sundvor; Godtliebsen, Fred; Ahluwalia, Balpreet Singh; Agarwal, Krishna (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-28)
      Multiple signal classification algorithm (MUSICAL) exploits temporal fluctuations in fluorescence intensity to perform super-resolution microscopy by computing the value of a super-resolving indicator function across a fine sample grid. A key step in the algorithm is the separation of the measurements into signal and noise subspaces, based on a single user-specified parameter called the threshold. ...
    • Software Radar signal processing. 

      Lind, F.D.; Grydeland, Tom; Holt, J.M.; Erickson, P.J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2005-01-31)
      Software infrastructure is a growing part of modern radio science systems. As part of developing a generic infrastructure for implementing Software Radar systems, we have developed a set of reusable signal processing components. These components are generic softwarebased implementations for use on general purpose computing systems. The components allow for the implementation of signal processing ...