https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 Influence of argon ion implantation on the thermoluminescence properties of aluminium oxide https://vital.seals.ac.za/vital/access/manager/Repository/vital:50173 Wed 20 Jul 2022 09:15:38 SAST ]]> Some ionospheric effects observed at sunrise https://vital.seals.ac.za/vital/access/manager/Repository/vital:5513 Wed 12 May 2021 23:37:53 SAST ]]> The development and evaluation of a Nd:YAG laser incorporating an unstable resonator https://vital.seals.ac.za/vital/access/manager/Repository/vital:5512 Wed 12 May 2021 23:35:05 SAST ]]> Finite precision arithmetic in Polyphase Filterbank implementations https://vital.seals.ac.za/vital/access/manager/Repository/vital:38503 Wed 12 May 2021 23:20:29 SAST ]]> Towards modelling the formation of ore bodies initial results dealing with the fluid mechanical aspects of magma chamber convection https://vital.seals.ac.za/vital/access/manager/Repository/vital:5492 Wed 12 May 2021 23:08:31 SAST ]]> An investigation into improved ionospheric F1 layer predictions over Grahamstown, South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5511 Wed 12 May 2021 22:45:13 SAST ]]> Comparison of A₄ neutrino mass models https://vital.seals.ac.za/vital/access/manager/Repository/vital:5554 Wed 12 May 2021 22:30:24 SAST ]]> Analysing emergent time within an isolated Universe through the application of interactions in the conditional probability approach https://vital.seals.ac.za/vital/access/manager/Repository/vital:38547 Wed 12 May 2021 20:57:26 SAST ]]> The 2326 MHZ radio continuum emission of the milky way https://vital.seals.ac.za/vital/access/manager/Repository/vital:5450 Wed 12 May 2021 20:17:57 SAST ]]> An analysis of ionospheric response to geomagnetic disturbances over South Africa and Antarctica https://vital.seals.ac.za/vital/access/manager/Repository/vital:5534 Wed 12 May 2021 20:15:43 SAST ]]> Nonlinear optical responses of phthalocyanines in the presence of nanomaterials or when embedded in polymeric materials https://vital.seals.ac.za/vital/access/manager/Repository/vital:25548 Wed 12 May 2021 20:07:23 SAST ]]> The photo-fluorescence properties of some organic materials https://vital.seals.ac.za/vital/access/manager/Repository/vital:5514 Wed 12 May 2021 20:04:33 SAST ]]> Observations of diffuse radio emission in the Perseus Galaxy Cluster https://vital.seals.ac.za/vital/access/manager/Repository/vital:38233 Wed 12 May 2021 19:59:26 SAST ]]> First H F Doppler soundings of the ionosphere at SANAE https://vital.seals.ac.za/vital/access/manager/Repository/vital:5500 Wed 12 May 2021 19:56:40 SAST ]]> Thermoluminescence of annealed synthetic quartz https://vital.seals.ac.za/vital/access/manager/Repository/vital:19957 Wed 12 May 2021 19:55:06 SAST ]]> Expanding the capabilities of the DPS lonosonde system https://vital.seals.ac.za/vital/access/manager/Repository/vital:5560 Wed 12 May 2021 19:50:08 SAST ]]> Tomographic imaging of East African equatorial ionosphere and study of equatorial plasma bubbles https://vital.seals.ac.za/vital/access/manager/Repository/vital:28516 Wed 12 May 2021 19:46:51 SAST ]]> Computer control of a barry research chirpsounder https://vital.seals.ac.za/vital/access/manager/Repository/vital:5507 Wed 12 May 2021 19:36:46 SAST ]]> Some properties of magnetospheric electrons observed west of Sanae https://vital.seals.ac.za/vital/access/manager/Repository/vital:5523 Wed 12 May 2021 19:23:20 SAST ]]> The C-Band : continuum mapping and measuring the radio environment https://vital.seals.ac.za/vital/access/manager/Repository/vital:5449 Wed 12 May 2021 19:06:39 SAST ]]> The selection and evaluation of grey-level thresholds applied to digital images https://vital.seals.ac.za/vital/access/manager/Repository/vital:5443 Wed 12 May 2021 18:55:44 SAST ]]> Thermoluminescence of synthetic quartz annealed beyond its second phase inversion temperature https://vital.seals.ac.za/vital/access/manager/Repository/vital:25577 Wed 12 May 2021 18:51:02 SAST ]]> A feasibility study into the possibility of ionospheric propagation of low VHF (30-35 MHZ) signals between South Africa and Central Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5465 Wed 12 May 2021 18:48:02 SAST ]]> Observation and processing of 2.3 GHz radio astronomy survey data https://vital.seals.ac.za/vital/access/manager/Repository/vital:5505 Wed 12 May 2021 18:42:52 SAST ]]> A study of why some physic concepts in the South African Physical Science curriculum are poorly understood in order to develop a targeted action-research intervention for Newton’s second law https://vital.seals.ac.za/vital/access/manager/Repository/vital:38575 Wed 12 May 2021 18:39:05 SAST ]]> Data reduction techniques for Very Long Baseline Interferometric spectropolarimetry https://vital.seals.ac.za/vital/access/manager/Repository/vital:5457 Wed 12 May 2021 18:24:03 SAST ]]> Thermoluminescence characteristics of synthetic quartz https://vital.seals.ac.za/vital/access/manager/Repository/vital:5538 Wed 12 May 2021 18:18:39 SAST ]]> Finite element simulations of shear aggregation as a mechanism to form platinum group elements (PGEs) in dyke-like ore bodies https://vital.seals.ac.za/vital/access/manager/Repository/vital:5561 Wed 12 May 2021 18:11:32 SAST ]]> Radio studies of ionized hydrogen in the southern Milky Way https://vital.seals.ac.za/vital/access/manager/Repository/vital:5440 Wed 12 May 2021 17:59:25 SAST ]]> Statistical study of traveling ionospheric disturbances over South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:30556 Wed 12 May 2021 17:50:57 SAST ]]> A study of the fluorescence excitation spectrum of crystalline anthracene https://vital.seals.ac.za/vital/access/manager/Repository/vital:5518 Wed 12 May 2021 17:49:58 SAST ]]> The variability and predictability of the IRI shape parameters over Grahamstown, South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5496 Wed 12 May 2021 17:49:23 SAST ]]> Statistical analysis of the ionospheric response during storm conditions over South Africa using ionosonde and GPS data https://vital.seals.ac.za/vital/access/manager/Repository/vital:5555 Wed 12 May 2021 17:41:38 SAST ]]> Ionospheric total electron content variability and its influence in radio astronomy https://vital.seals.ac.za/vital/access/manager/Repository/vital:5473 Wed 12 May 2021 17:41:31 SAST ]]> Ionospheric disturbances during magnetic storms at SANAE https://vital.seals.ac.za/vital/access/manager/Repository/vital:26639 Wed 12 May 2021 17:31:19 SAST ]]> Temperature dependence of the HartRAO pointing model https://vital.seals.ac.za/vital/access/manager/Repository/vital:5491 Wed 12 May 2021 17:23:16 SAST ]]> A real time Fast Fourier Transform analyser https://vital.seals.ac.za/vital/access/manager/Repository/vital:5439 Wed 12 May 2021 17:22:56 SAST ]]> Verification of Ionospheric tomography using MIDAS over Grahamstown, South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5497 Wed 12 May 2021 17:18:51 SAST ]]> A real time HF beacon monitoring station for South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5486 Wed 12 May 2021 16:17:43 SAST ]]> A feasibility study into total electron content prediction using neural networks https://vital.seals.ac.za/vital/access/manager/Repository/vital:5466 Wed 12 May 2021 16:16:20 SAST ]]> PyMORESANE: A Pythonic and CUDA-accelerated implementation of the MORESANE deconvolution algorithm https://vital.seals.ac.za/vital/access/manager/Repository/vital:5563 Wed 12 May 2021 16:14:42 SAST ]]> Using co-located radars and instruments to analyse ionespheric events over South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5493 Wed 12 May 2021 15:59:02 SAST ]]> Statistical Analysis of the Radio-Interferometric Measurement Equation, a derived adaptive weighting scheme, and applications to LOFAR-VLBI observation of the Extended Groth Strip https://vital.seals.ac.za/vital/access/manager/Repository/vital:30942 Wed 12 May 2021 15:54:37 SAST ]]> A study of atmospheric oscillations in the meteor region above Grahamstown https://vital.seals.ac.za/vital/access/manager/Repository/vital:5490 :30'E) meteor radar between the years 1987 and 1993 inclusive. Harmonic analysis and the maximum entropy method (MEM) , were used for the spectral characterization ofthe wind above Grahamstown. The prevailing wind, tidal (periods 12- and 24- h) and other (periods 8- and 6-h) oscillations were extracted from the data using the guidelines agreed upon by the A TMAP community. Above Grahamstown the zonal and meridional prevailing winds were found to be predominantly eastward and equatorward respectively. Tidal amplitudes are comparable to the magnitude of the prevailing wind vector, with the diurnal tide being stronger than the semidiurnal tide. The phase differences between ,the zonal and meridional components of the semidiurnal and diurnal tides are - 2 hand - 5 h respectively, which is in reasonable agreement with the corresponding expected values of3 hand 6 h. The tidal wind vectors are on average elliptically polarized with anticlockwise rotation. Longitudinal and day-to-day tidal variations were studied. From the longitudinal study, the semidiurnal tide was found to be dominated by migrating modes, while the diurnal tidal behaviour suggests the presence of nonmigrating modes with zonal wavenumber s = 4. Tides were found to be variable from day to day with little apparent correlation between the zonal and meridional components of the respective tides.]]> Wed 12 May 2021 15:49:24 SAST ]]> The utilization of tilting-filter photometry in airglow and auroral research https://vital.seals.ac.za/vital/access/manager/Repository/vital:5494 Wed 12 May 2021 15:48:31 SAST ]]> Observations of cosmic re-ionisation with the Hydrogen Epoch of Reionization Array: simulations of closure phase spectra https://vital.seals.ac.za/vital/access/manager/Repository/vital:42480 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.]]> Wed 12 May 2021 14:24:29 SAST ]]> Design patterns and software techniques for large-scale, open and reproducible data reduction https://vital.seals.ac.za/vital/access/manager/Repository/vital:42172 Wed 12 May 2021 13:59:27 SAST ]]> Third generation calibrations for Meerkat Observation of Saraswati Supercluster https://vital.seals.ac.za/vital/access/manager/Repository/vital:65374 Wed 10 Jan 2024 11:01:27 SAST ]]> The effects of particle precipitation on the ionosphere in the South Atlantic Anomaly Region https://vital.seals.ac.za/vital/access/manager/Repository/vital:5463 Tue 31 Aug 2021 10:06:57 SAST ]]> Predictability of Geomagnetically Induced Currents using neural networks https://vital.seals.ac.za/vital/access/manager/Repository/vital:5483 Thu 26 Aug 2021 14:37:41 SAST ]]> The EPR paradox: back from the future https://vital.seals.ac.za/vital/access/manager/Repository/vital:20338 Thu 23 Jun 2022 11:24:04 SAST ]]> Dynamics of stimulated luminescence in natural quartz: Thermoluminescence and phototransferred thermoluminescence https://vital.seals.ac.za/vital/access/manager/Repository/vital:38509 Thu 13 May 2021 15:55:13 SAST ]]> CubiCal: a fast radio interferometric calibration suite exploiting complex optimisation https://vital.seals.ac.za/vital/access/manager/Repository/vital:30711 Thu 13 May 2021 15:04:39 SAST ]]> The implementation of a core architecture for geophysical data acquisition https://vital.seals.ac.za/vital/access/manager/Repository/vital:5471 Thu 13 May 2021 13:16:36 SAST ]]> A new empirical model for the peak ionospheric electron density using neural networks https://vital.seals.ac.za/vital/access/manager/Repository/vital:5478 Thu 13 May 2021 07:39:27 SAST ]]> Measuring the RFI environment of the South African SKA site https://vital.seals.ac.za/vital/access/manager/Repository/vital:5474 Thu 13 May 2021 07:16:45 SAST ]]> Long-term analysis of ionospheric response during geomagnetic storms in mid, low and equatorial latitudes https://vital.seals.ac.za/vital/access/manager/Repository/vital:28517 Thu 13 May 2021 07:06:25 SAST ]]> Calibration and interpretation of A 2.3 GHz continuum survey https://vital.seals.ac.za/vital/access/manager/Repository/vital:5502 L > -58° is studied. It is dominated by a plateau of emission for L < -26°. This is interpreted as a combination of thermal and nonthermal radiation emitted by a ring of gas symmetric about the galactic centre with a radius of 4 - 6 kpc.]]> Thu 13 May 2021 06:53:12 SAST ]]> The effect of different parameters on the rupture properties of leather in a tensile test https://vital.seals.ac.za/vital/access/manager/Repository/vital:5462 Thu 13 May 2021 06:48:58 SAST ]]> Studies in ionospheric ray tracing https://vital.seals.ac.za/vital/access/manager/Repository/vital:5501 Thu 13 May 2021 06:28:30 SAST ]]> A VLBI study of OH masers in a proto-planetary nebula OH 0.9+1.3 https://vital.seals.ac.za/vital/access/manager/Repository/vital:5499 Thu 13 May 2021 06:26:01 SAST ]]> Multi-instrument observations of ionospheric irregularities over South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5476 Thu 13 May 2021 06:18:50 SAST ]]> Observations of glitches in PSR 0833-45 and 1641-45 https://vital.seals.ac.za/vital/access/manager/Repository/vital:5480 Thu 13 May 2021 06:12:50 SAST ]]> Real-time audio spectrum analyser research, design, development and implementation using the 32 bit ARMR Cortex-M4 microcontroller https://vital.seals.ac.za/vital/access/manager/Repository/vital:25997 Thu 13 May 2021 06:12:17 SAST ]]> Link between ghost artefacts, source suppression and incomplete calibration sky models https://vital.seals.ac.za/vital/access/manager/Repository/vital:5556 Thu 13 May 2021 06:07:57 SAST ]]> A Bayesian approach to tilted-ring modelling of galaxies https://vital.seals.ac.za/vital/access/manager/Repository/vital:38466 Thu 13 May 2021 05:58:42 SAST ]]> Solar cycle effects on GNSS-derived ionospheric total electron content observed over Southern Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5489 Thu 13 May 2021 05:54:01 SAST ]]> Observing cosmic reionization with PAPER: polarized foreground simulations and all sky images https://vital.seals.ac.za/vital/access/manager/Repository/vital:29218 0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.]]> Thu 13 May 2021 05:43:39 SAST ]]> MEQSILHOUETTE: a mm-VLBI observation and signal corruption simulator https://vital.seals.ac.za/vital/access/manager/Repository/vital:25019 Thu 13 May 2021 05:32:08 SAST ]]> Modelling and investigating primary beam effects of reflector antenna arrays https://vital.seals.ac.za/vital/access/manager/Repository/vital:38635 Thu 13 May 2021 05:23:36 SAST ]]> Thermoluminescence of natural quartz https://vital.seals.ac.za/vital/access/manager/Repository/vital:5543 Thu 13 May 2021 05:21:09 SAST ]]> The SKA's the limit : on the nature of faint radio sources https://vital.seals.ac.za/vital/access/manager/Repository/vital:5504 Thu 13 May 2021 05:20:46 SAST ]]> A neural network based ionospheric model for the bottomside electron density profile over Grahamstown, South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5477 Thu 13 May 2021 05:19:34 SAST ]]> Optimizing MIDAS III over South Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5517 Thu 13 May 2021 05:10:35 SAST ]]> The observation of extended sources with the Hartebeesthoek radio telescope https://vital.seals.ac.za/vital/access/manager/Repository/vital:5479 Thu 13 May 2021 05:09:50 SAST ]]> A pilot wide-field VLBI survey of the GOODS-North field https://vital.seals.ac.za/vital/access/manager/Repository/vital:30027 5x105 K and >6x1021 W Hz-1 respectively. This work demonstrates that automated post-processing pipelines for wide-field, uniform sensitivity VLBI surveys are feasible and indeed made more efficient with new software, wide-field imaging algorithms and more purpose-built source- finders. This broadens the discovery space for future wide-field surveys with upcoming arrays such as the African VLBI Network (AVN), MeerKAT and the Square Kilometre Array (SKA).]]> Thu 13 May 2021 05:08:27 SAST ]]> Empirical modelling of the solar wind influence on Pc3 pulsation activity https://vital.seals.ac.za/vital/access/manager/Repository/vital:5464 Thu 13 May 2021 05:04:36 SAST ]]> The establishment of a Lidar facility at Rhodes University https://vital.seals.ac.za/vital/access/manager/Repository/vital:5445 Thu 13 May 2021 04:52:35 SAST ]]> Calibration and imaging with variable radio sources https://vital.seals.ac.za/vital/access/manager/Repository/vital:24721 Thu 13 May 2021 04:51:42 SAST ]]> The search for an ionospheric model suitable for real-time applications in HF radio communications https://vital.seals.ac.za/vital/access/manager/Repository/vital:5488 Thu 13 May 2021 04:41:21 SAST ]]> A 150 MHz all sky survey with the Precision Array to Probe the Epoch of Reionization https://vital.seals.ac.za/vital/access/manager/Repository/vital:34556 Thu 13 May 2021 04:40:36 SAST ]]> Physics and applications of scintillation detectors https://vital.seals.ac.za/vital/access/manager/Repository/vital:5482 Thu 13 May 2021 04:31:15 SAST ]]> Finite element modelling of magma convection and attendant groundwater flow https://vital.seals.ac.za/vital/access/manager/Repository/vital:5467 Thu 13 May 2021 04:24:15 SAST ]]> The development of an improved coded-pulse, vertical-incidence ionosonde https://vital.seals.ac.za/vital/access/manager/Repository/vital:5436 Thu 13 May 2021 03:43:09 SAST ]]> Thermoluminescence and phototransferred phermoluminescence of synthetic quartz https://vital.seals.ac.za/vital/access/manager/Repository/vital:38472 Thu 13 May 2021 03:05:20 SAST ]]> Modelling Ionospheric vertical drifts over the African low latitude region https://vital.seals.ac.za/vital/access/manager/Repository/vital:28396 Thu 13 May 2021 02:06:20 SAST ]]> Foreground simulations for observations of the global 21-cm signal https://vital.seals.ac.za/vital/access/manager/Repository/vital:30557 Thu 13 May 2021 01:46:55 SAST ]]> Beta decay of 100/400 Zr produced in neutron-induced fission of natural uranium https://vital.seals.ac.za/vital/access/manager/Repository/vital:20353 Thu 13 May 2021 01:43:27 SAST ]]> Geomagnetically induced current characteristics in southern Africa https://vital.seals.ac.za/vital/access/manager/Repository/vital:5469 Thu 13 May 2021 01:31:54 SAST ]]> Advanced radio interferometric simulation and data reduction techniques https://vital.seals.ac.za/vital/access/manager/Repository/vital:26875 Thu 13 May 2021 01:03:59 SAST ]]> Computer control of an HF chirp radar https://vital.seals.ac.za/vital/access/manager/Repository/vital:5455 Thu 13 May 2021 00:45:07 SAST ]]> A contribution to TEC modelling over Southern Africa using GPS data https://vital.seals.ac.za/vital/access/manager/Repository/vital:5456 Thu 13 May 2021 00:26:54 SAST ]]> Variability analysis of a sample of potential southern calibration sources https://vital.seals.ac.za/vital/access/manager/Repository/vital:5495 Thu 13 May 2021 00:13:28 SAST ]]> Semantic segmentation of astronomical radio images: a computer vision approach https://vital.seals.ac.za/vital/access/manager/Repository/vital:71937 Thu 04 Apr 2024 19:33:11 SAST ]]> MeerKAT observations of three high-redshift galaxy clusters https://vital.seals.ac.za/vital/access/manager/Repository/vital:71936 6×1014 M⊙ at intermediate redshifts (0.3 < z < 0.4), providing support to their connection between mergers, which provide the necessary energy to re-accelerate particles via turbulence. Probing the redshift evolution of radio halos is an important test of the turbulent re-acceleration scenario, as fewer halos are expected at high redshift, given the same mass interval. In this thesis, we present MeerKAT observations at 1.28 GHz of three high-redshift (PSZ2G254.08- 58.45, PSZ2G255.60-46.18 and PSZ2G277.76-51.74, in the 0.42 ≲ z ≲ 0.46 range) clusters, with masses M500 ≳ 6.2 × 1014 M⊙, selected for their disturbed dynamical state – inferred from existing X-ray observations. Our observations reached rms noise values between 20 and 23.5 μJy beam−1, with ∼ 4′′ angular resolution. No evidence of diffuse emission is found at ii full resolution. Low-resolution (∼ 30′′) images achieved rms noise levels of 30-50 μJy beam−1, amongst the deepest observations of high-redshift targets. One radio halo was detected in the least massive cluster PSZ2G254.08-58.45 extending over ∼ 500 kpc, with a 1.20 } 0.08 mJy integrated flux density. We placed a ∼1 mJy upper limit at 95% confidence level on the radio halo flux density for the other two targets. The radio-halo detection is consistent with the recent P1.4 GHz − M500 correlation from Cuciti et al. (2021b), while the upper limit on PSZ2G255.60-46.18 is consistent with being on the correlation. On the other hand, the upper limit on PSZ2G277.76-51.74 places the radio halo well below the correlation. Recently a 1.5 GHz survey (Giovannini et al., 2020) detected a slightly higher fraction of radio halos in clusters in the same redshift range, with power and size typically higher than what we found in our observations. Both observations are, however, not inconsistent with each other. Our results, although with limited statistics, do not disfavour the current scenario of radiohalo formation based on the turbulent re-acceleration model.]]> Thu 04 Apr 2024 19:25:15 SAST ]]> An investigation of traveling ionospheric disturbances (TIDs) in the SANAE HF radar data https://vital.seals.ac.za/vital/access/manager/Repository/vital:49986 Sun 09 Oct 2022 17:48:47 SAST ]]> Dynamics of charge movement in ∞-Al2O3:C,Mg using thermoluminescence phototransferred and optically stimulated luminescence https://vital.seals.ac.za/vital/access/manager/Repository/vital:57237 Mon 24 Oct 2022 14:52:01 SAST ]]> Night-time gravity waves detected with multi-frequency airglow imager https://vital.seals.ac.za/vital/access/manager/Repository/vital:42931 Mon 17 May 2021 13:00:31 SAST ]]> Neutral Atomic Hydrogen in Gravitationally Lensed Systems https://vital.seals.ac.za/vital/access/manager/Repository/vital:45263 Mon 15 Nov 2021 14:52:54 SAST ]]> Data compression, field of interest shaping and fast algorithms for direction-dependent deconvolution in radio interferometry https://vital.seals.ac.za/vital/access/manager/Repository/vital:21089 Fri 07 Jul 2023 06:30:13 SAST ]]>