Now showing items 411-430 of 675

    • Modelling the average spectrum expected from a population of gamma-ray globular clusters 

      Venter, C.; Kopp, A. (SAIP, 2015)
      Millisecond pulsars occur abundantly in globular clusters. They are expected to be responsible for several spectral components in the radio through γ-ray waveband (e.g., involving synchrotron and inverse Compton emission), ...
    • Modelling the growing population of y-ray millisecond pulsars 

      Venter, C.; Harding, A.K.; Johnson, T.J. (Springer, 2011)
      TheFermiLarge Area Telescope, in collaboration with several groups from the radio community, have had marvellous success at uncovering new γ-ray millisecond pulsars (MSPs). In fact, MSPs now make up a sizable fraction of ...
    • Modelling the light curves of Fermi LAT millisecond pulsars 

      Venter, C.; Johnson, T.J.; Harding, A.K.; Grove, J.E. (South African Institute of Physics, 2014)
      There are 40 millisecond pulsars (MSPs) in the second pulsar catalogue of the Fermi Large Area Telescope (LAT). This pulsar subpopulation is unique owing to their relatively small magnetospheres. This may result in radio ...
    • Modelling the polarisation signatures detected from the first white dwarf pulsar AR Sco. 

      Du Plessis, L.; Wadiasingh, Z.; Venter, C.; Chandra, S.; Harding, A.K. (Sissa Medialab, 2018)
      Marsh et al. (2016) detected radio and optical pulsations from the binary system AR Scorpii (AR Sco). This system, with an orbital period of 3.55 h, is composed of a cool, low-mass star and a white dwarf with a spin period ...
    • Modelling the stellar soft-photon energy density of globular clusters 

      Prinsloo, Phillip L.; Venter, Christo; Busching, Ingo; Kopp, Andreas (South African Institute of Physics, 2014)
      Recent observations by e.g. Fermi LAT and H.E.S.S. have revealed globular clusters to be sources of high-energy and very-high-energy gamma rays. It has been suggested that the presence of large numbers of millisecond pulsars ...
    • Modelling the y-ray and radio light curves of the double pulsar system 

      Seyffert, A.S.; Venter, C.; Harding, A.K.; Johnson, T.J. (South African Institute of Physics, 2014)
      Guillemot et al. recently reported the discovery [1] of -ray pulsations from the 22.7 ms pulsar (pulsar A) in the famous double pulsar system J0737−3039A/B. The -ray light curve (LC) of pulsar A has two peaks separated ...
    • Modernising underground compressed air DSM projects to reduce operating costs 

      Kriel, C.J.R.; Marais, J.H.; Kleingeld, M. (IEEE, 2014)
      Compressed air is an energy intensive utility that is frequently used in the deep level mining industry. Most compressed air networks are designed to ensure ample compressed air supply to consumers. This has created the ...
    • Modified earliest decoding for random network codes 

      Von Solms, Suné; Helberg, Albert S.J. (IEEE, 2011)
      We present a practical, modified version of earliest decoding for random linear network coding networks. This decoding method has a lower complexity and decoding delay than traditional Gaussian elimination decoding schemes
    • Monitoring gearbox oil viscosity by means of motor current signal analysis 

      Van Vuuren, Pieter A.; Xu, Yuandong; Gu, Fengshou; Ball, Andrew D. (Univ of Huddersfield, 2017)
      A number of gearbox failures can be attributed to lubricant related problems. One measure of the condition of gearbox oil is its viscosity. In electrically powered systems, motor current signal analysis allows online ...
    • Monitoring of the FSRQ PKS 1510-089 with H.E.S.S. 

      Zacharias, Michael; Jankowsky, Felix; Mohamed, Mahmoud; Prokoph, Heike; Sanchez, David (PoS, 2017)
      The flat spectrum radio quasar (FSRQ) PKS 1510-089 (z=0.361) is known for its complex multiwavelength behavior. It has been monitored regularly at very high energy (VHE, E > 100GeV) gamma-rays with H.E.S.S. since its ...
    • Monomers, polymers and cross-linked membranes for membrane fuel cells and electrolysis 

      Kerres, Jochen A.; Krüger, Andries; Schoeman, Hannes; Bessarabov, Dmitri; Krieg, Henning (Electrochemical Society, 2011)
      This contribution comprises an overview about work in the development of ionomers/ionomer (blend) membranes for fuel cells. The topics include the development of novel sulfonated monomers and homo- and copolymers; the ...
    • Moving households to cleaner energy through air quality offsets 

      Langerman, Kristy E.; Piketh, Stuart J.; Pauw, Christiaan J.; Smith, Hendrik J. (IEEE, 2018)
      Highest levels of exposure to polluted air in South Africa occur in low-income settlements where households burn solid fuels. The Department of Environmental Affairs has recently developed a legally enforceable mechanism ...
    • MSP binaries as astrophysical laboratories 

      Wadiasingh, Zorawar; Venter, Christo; Böttcher, Markus; Harding, Alice K.; Baring, Matthew G. (Cambridge Univ Press, 2018)
      Follow-up of unidentified Fermi sources has expanded the number of known galactic-field “black widow” and “redback” millisecond pulsar binaries from four to nearly 30. Several systems observed by Chandra, XMM-Newton, Suzaku, ...
    • Multi-wavelength observations of flaring blazars with ATOM and Fermi-LAT 

      Jankowsky, Felix; Böttcher, Markus; Zacharias, Michael; Wagner, Stefan J.; Kurtanidze, Omar (Sissa Medialab, 2017)
      The Automatic Telescope for Optical Monitoring is a 75cm optical telescope located at the H.E.S.S. site in Namibia. Since 2005, it monitors around 250 gamma-ray emitting AGN and has observed numerous blazar flares in several ...
    • Multifaceted nanominerals and ultrafine particles in phosphogypsum: a by-product of coal cleaning rejects 

      De Leão, Felipe B.; Waanders, F.; Taffarel, S.; Sampaio, C.; Lima, B. (International Pittsburgh Coal Conference, 2016)
    • Multivariable H∞ control for an active magnetic bearing flywheel system 

      Steyn, S.J.M.; Van Vuuren, P.A.; Van Schoor, G. (IET, 2010)
      A state-space model with uncertainties for an active magnetic bearing energy storage flywheel system (Fly-UPS) is developed. A multivariable robust H∞ controller for the Fly-UPS is then synthesised. Different weighting ...
    • Multiwavelength analysis of four millisecond pulsars 

      Guillemot, L.; Venter, C.; Cognard, I.; Johnson, T.J.; Harding, A.K.; Fermi LAT (AIPC, 2011)
      Radio timing observations of millisecond pulsars (MSPs) in support of Fermi LAT observations of the gamma-ray sky enhance the sensitivity of high-energy pulsation searches. With contemporaneous ephemerides we have detected ...
    • Multiwavelength modeling of the globular cluster Terzan 5 

      Büsching, I.; Venter, C.; Kopp, A.; De Jager, O.C.; Clapson, A.C. (ICRC, 2011)
      Diffuse X-ray emission has recently been detected from the globular cluster (GC) Terzan 5, extending out to ~2.5' from the cluster centre. This emission may arise from synchrotron radiation (SR) by energetic leptons being ...
    • Multiwavelength polarization as a diagnostic of blazar physics 

      Böttcher, Markus; Zhang, Haocheng; Chen, Xuhui (Sissa Medialab, 2015)
      The nature of the high-energy emission in jet-dominated AGN (especially blazars) as well as the location and mode of acceleration of particles to ultra- relativistic energies are a matter of intensive debate. Both leptonic ...