Recent additions

  • RS-HeRR: a rough set-based Hebbian rule reduction neuro-fuzzy system 

    Liu, Feng; Sekh, Arif Ahmed; Quek, Chai; Ng, Geok See; Prasad, Dilip K. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-01)
    Interpretabilty is one of the desired characteristics in various classification task. Rule-based system and fuzzy logic can be used for interpretation in classification. The main drawback of rule-based system is that it may contain large complex rules for classification and sometimes it becomes very difficult in interpretation. Rule reduction is also difficult for various reasons. Removing important ...
  • Oscillations:Linear theory and applications in AFM 

    Olukan, Tuza Adeyemi; Santos, Sergio; Elsherbiny, Lamia; Chiesa, Matteo (Research report; Forskningsrapport, 2022)
    The theory of oscillations can be studied from a mathematical point of view in terms of differential equations. The differential equation is written and then the solution or solutions worked out and mathematically analysed. Provided physical, economic, social, or other phenomena can be modelled in terms of equivalent differential equations, the solutions and results are applicable to all phenomena ...
  • Multifocus microscopy with optical sectioning and high axial resolution 

    Ströhl, Florian; Hansen, Daniel Henry; Nàger, Mireia; Birgisdottir, Åsa birna (Journal article; Tidsskriftartikkel; Peer reviewed, 2022)
    Multifocus microscopy enables recording of entire volumes in a single camera 11 exposure. In dense samples, multifocus microscopy is severely hampered by background haze. 12 Here, we introduce a scalable multifocus method that incorporates optical sectioning and offers 13 improved axial resolution capabilities. In our method, a dithered oblique light-sheet scans the 14 sample volume during a ...
  • Springtime nitrogen oxides and tropospheric ozone in Svalbard: results from the measurement station network 

    Dekhtyareva, Alena; Hermanson, Mark H.; NIkulina, Anna; Hermansen, Ove; Svendby, Tove Marit; Holmén, Kim; Graversen, Rune Grand (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-09)
    Svalbard is a remote and scarcely populated Arctic archipelago and is considered to be mostly influenced by long-range-transported air pollution. However, there are also local emission sources such as coal and diesel power plants, snowmobiles and ships, but their influence on the background concentrations of trace gases has not been thoroughly assessed. This study is based on data of tropospheric ...
  • Rapid Colorimetric pH-Responsive Gold Nanocomposite Hydrogels for Sensing Applications 

    Salih, Ahmed E.; Elsherif, Mohamed; Alam, Fahad; Chiesa, Matteo; Butt, Haider (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-27)
    Surface functionalization of metallic nanoparticles (NPs) with external groups can be engineered to fabricate sensors that are responsive to various stimuli like temperature, pH, and numerous ions. Herein, we report the synthesis of gold nanoparticles (GNPs) functionalized with 3-mercaptopropionic acid (GNPs-MPA) and the doping of these nanoparticles into hydrogel materials using the ...
  • 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 ...
  • Imaging the Effects of Whole-Body Vibration on the Progression of Hepatic Steatosis by Quantitative Ultrasound Based on Backscatter Envelope Statistics 

    Fang, Jui; Lai, Ming-Wei; Cheng, Hao-Tsai; Cristea, Anca; Zhou, Zhuhuang; Tsui, Po-Hsiang (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-29)
    Hepatic steatosis causes nonalcoholic fatty liver disease. Whole-body vibration (WBV) has been recommended to allow patients who have difficulty engaging in exercise to improve the grade of hepatic steatosis. This study proposed using ultrasound parametric imaging of the homodyned K (HK) distribution to evaluate the effectiveness of WBV treatments in alleviating hepatic steatosis. Sixty mice were ...
  • Multiple E-Region Radar Propagation Modes Measured by the VHF SIMONe Norway System During Active Ionospheric Conditions 

    Huyghebaert, Devin Ray; Clahsen, Matthias; Chau, Jorge L.; Renkwitz, Toralf; Latteck, Ralph; Johnsen, Magnar Gullikstad; Vierinen, Juha (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-10)
    Multiple propagation modes between different bistatic radar links were measured during the operations of a very high frequency (VHF) 32.55 MHz radar system in northern Norway. The Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) Norway system detected meteor trails, direct transmitter to receiver signal propagation, over-the-horizon signal propagation from the ...
  • On the determination of ionospheric electron density profiles using multi-frequency riometry 

    McKay, Derek; Vierinen, Juha; Kero, Antti; Partamies, Noora (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-27)
    Radio wave absorption in the ionosphere is a function of electron density, collision frequency, radio wave polarisation, magnetic field and radio wave frequency. Several studies have used multi-frequency measurements of cosmic radio noise absorption to determine electron density profiles. Using the framework of statistical inverse problems, we investigated if an electron density altitude profile ...
  • Performance Analysis of Roll-Invariant PolSAR Parameters from C-band images with Regard to Sea Ice Type Separation 

    Ratha, Debanshu; Johansson, Malin; Marinoni, Andrea; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06)
    The Polarimetric Synthetic Aperture Radar (PolSAR) backscatter from a target is dependent on the incidence angle. Consequently, the associated roll invariant parameters are affected by changes in incidence angle. In this work, we identify a few of these parameters that remain robust in identifying sea ice features even under large incidence angle variations. We conclude that the helicity angle ...
  • An alternative approach for calculating the SAR damping ratio of verified oil slicks 

    Quigley, Cornelius Patrick; Johansson, Malin; Jones, Cathleen Elaine (Journal article; Tidsskriftartikkel; Peer reviewed, 2022)
    The damping ratio is a calculated feature that measures the contrast between oil-slicked water and the open ocean in SAR data. To implement the damping ratio, the current literature suggests estimating the open water backscatter by taking strips of undefined width across the range direction, obtaining the damping ratio as a function of incidence angle. We show in this paper that the method proposed ...
  • Horizontal Wavenumber Spectra of Vertical Vorticity and Horizontal Divergence of Mesoscale Dynamics in the Mesosphere and Lower Thermosphere Using Multistatic Specular Meteor Radar Observations 

    Poblet, Facundo; Chau, Jorge L.; Conte, J. F.; Avsarkisov, Victor; Vierinen, Juha; Asokan, Harikrishnan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-24)
    Specular meteor radars (SMRs) have significantly contributed to the understanding of wind dynamics in the mesosphere and lower thermosphere (MLT). We present a method to estimate horizontal correlations of vertical vorticity (Qzz) and horizontal divergence (P) in the MLT, using line-of-sight multistatic SMRs velocities, that consists of three steps. First, we estimate 2D, zonal, and meridional ...
  • Chip-based multimodal super-resolution microscopy for histological investigations of cryopreserved tissue sections 

    Villegas, Luis; Dubey, Vishesh Kumar; Nystad, Mona; Tinguely, Jean-Claude; Coucheron, David Andre; Dullo, Firehun Tsige; Priyadarshi, Anish; Acuna Maldonado, Sebastian Andres; Ahmad, Azeem; Mateos, Jose M.; Barmettler, Gery; Ziegler, Urs; Birgisdottir, Åsa Birna; Hovd, Aud-Malin Karlsson; Fenton, Kristin Andreassen; Acharya, Ganesh; Agarwal, Krishna; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-24)
    Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in histological investigations, their resolving capabilities are insufficient to visualize details at subcellular level. Although a novel set of super-resolution optical microscopy techniques can fulfill the resolution demands in such cases, the ...
  • Towards robust partially supervised multi-structure medical image segmentation on small-scale data 

    Dong, Nanqing; Kampffmeyer, Michael; Liang, Xiaodan; Xu, Min; Voiculescu, Irina; Xing, Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-20)
    The data-driven nature of deep learning (DL) models for semantic segmentation requires a large number of pixel-level annotations. However, large-scale and fully labeled medical datasets are often unavailable for practical tasks. Recently, partially supervised methods have been proposed to utilize images with incomplete labels in the medical domain. To bridge the methodological gaps in ...
  • Frequency spectra of horizontal winds in the mesosphere and lower thermosphere region from multistatic specular meteor radar observations during the SIMONe 2018 campaign 

    Charuvil, Harikrishnan; Chau, Jorge L.; Marino, Raffaele; Vierinen, Juha; Vargas, Fabio; Urco, Juan M.; Clahsen, Matthias; Jacobi, Christoph (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-11)
    In recent years, multistatic specular meteor radars (SMRs) have been introduced to study the Mesosphere and Lower Thermosphere (MLT) dynamics with increasing spatial and temporal resolution. SMRs, compared to other groundbased observations, have the advantage of continuously measuring the region between 80 and 100 km independent of weather, season, or time of day. In this paper, frequency spectra ...
  • Multi-moded high-index contrast optical waveguide for super-contrast high-resolution label-free microscopy 

    Jayakumar, Nikhil; Dullo, Firehun Tsige; Dubey, Vishesh Kumar; Ahmad, Azeem; Ströhl, Florian; Cauzzo, Jennifer; Mazagao Guerreiro, Eduarda; Snir, Omri; Skalko-Basnet, Natasa; Agarwal, Krishna; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-20)
    The article elucidates the physical mechanism behind the generation of superior-contrast and highresolution label-free images using an optical waveguide. Imaging is realized by employing a high index contrast multi-moded waveguide as a partially coherent light source. The modes provide near-field illumination of unlabeled samples, thereby repositioning the higher spatial frequencies of the ...
  • Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar 

    Viswanathan, Lakshmi Narayanan; Häggström, Ingemar; Mann, Ingrid (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-23)
    We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased ...
  • A Stimulated Emission Diagnostic Technique for Electron Temperature of the High Power Radio Wave Modified Ionosphere 

    Fu, Haiyang; Jiang, M. L.; Vierinen, Juha; Häggström, Ingemar; Rietveld, Michael T.; Varberg, Erik; Sato, Hiroatsu; Wu, Jiang; Scales, Wayne A.; Jin, Y. Q. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-09)
    We report observations of stimulated electromagnetic emission (SEE) induced by high power high frequency (HF) radio waves near the third electron gyroharmonic (3urn:x-wiley:00948276:media:grl64672:grl64672-math-0022) at European Incoherent Scatter Radar (EISCAT). It is discovered that stimulated Brillouin scattering (SBS) spectrum behaves similarly as spectral ion lines of the incoherent scatter ...
  • A 30-year probability map for oil spill trajectories in the barents sea to assess potential environmental and socio-economic threats 

    Pavlov, Victor; Martins de Aguiar, Victor Cesar; Hole, Lars Robert; Pongrácz, Eva (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)
    Increasing exploration and exploitation activity in the Arctic Ocean has intensified maritime traffic in the Barents Sea. Due to the sparse population and insufficient oil spill response infrastructure on the extensive Barents Sea shoreline, it is necessary to address the possibility of offshore accidents and study hazards to the local environment and its resources. Simulations of surface oil ...
  • Unbalanced low coherence interference microscopy 

    Ahmad, Azeem; Habib, Anowarul; Dubey, Vishesh Kumar; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-03)
    Low coherence interference microscopy (LCIM) provides high spatial phase sensitivity, i.e., speckle free and coherent noise free quantitative phase images of the test specimens. Due to low temporal coherence (TC) length of the light source, LCIM requires precise adjustment of the optical path difference (OPD) between the object and the reference arm, which is only a few micrometers. Consequently, ...

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