T.L. Grobler


CONTACT INFORMATION

Computer Science Division

Department of Mathematical Sciences

University of Stellenbosch

Private Bag X1, Matieland 7602

South Africa



A510, General Engineering Building

University of Stellenbosch

c.o. Banghoek Road and Joubert Street

Stellenbosch, South Africa

Tel: +27 21 808 4232 (administrative officer)

E-mail: tlgrobler@sun.ac.za


BIO


I obtained my master’s degree in Computer Engineering at the University of Pretoria (UP), the focus of which was coding theory. Thereafter, I was employed by Telkom for two years, where I worked as a software engineer and took part in the development of an enterprise application that could configure multi-domain Synchronous Digital Hierarchy (SDH) services. At Telkom I obtained sought after industry experience. My true passion, however, is research, which is why I applied for a PhD studentship at the Council for Scientific and Industrial Research (CSIR). At the CSIR I made use of statistics and satellite data to detect and monitor settlement expansion in the South African provinces of Gauteng and Limpopo. The research I conducted at the CSIR also enabled me to complete a PhD in Computer Engineering at UP. I also have a passion for mathematics, which is why I also completed some additional subjects during my years at the CSIR namely, real analysis, stochastic calculus and abstract algebra. After obtaining my PhD I accepted a postdoctoral fellowship at Rhodes University. At Rhodes University I worked on the Square Kilometer Array (SKA) project. More specifically, I worked on the calibration of radio interferometers. I also had the opportunity to complete a summer internship at the Netherlands Institute for Radio Astronomy (ASTRON) and to attend the summer HERA cohort program at the University of California. From Rhodes University I moved to Stellenbosch University, where I was appointed as a lecturer in the Computer Science Division.


QUALIFICATIONS




RESEARCH


RESEARCH INTERESTS


My research interests include: the application of machine learning to radio astronomy and remote sensing, and the proper design of radio interferometric reduction pipelines.


REFEREED CONFERENCE PROCEEDINGS


  1. T.L. Grobler and W.T. Penzhorn, “Fast decryption methods for the RSA Cryptosystem”, Southern African Telecommunication Networks and Applications Conference, Cape Town, South Africa, September 2006.

  2. T.L. Grobler, J.C. Olivier and J.D. Vlok, “Fountain codes and their possible application in standards like GSM”, Southern African Telecommunication Networks and Applications Conference, Mauritius, September 2007.

  3. E.R. Ackermann, T.L. Grobler, A.J. van Zyl, K.C. Steenkamp and J.C. Olivier, “Minimum error land cover separability analysis and classification of MODIS time series data”, IEEE International Geoscience and Remote Sensing Symposium, Vancouver, Canada, July 2011.

  4. T.L. Grobler, E.R. Ackermann, J.C. Olivier and A.J. van Zyl, “Systematic Luby Transform codes as incremental redundancy scheme”, AFRICON, Livingston, Zambia, September 2011.

  5. E.R. Ackermann, T.L. Grobler, A.J. van Zyl and J.C. Olivier, “Belief propagation for nonlinear block codes”, AFRICON, Livingston, Zambia, September 2011.

  6. B.P. Salmon, W. Kleynhans , F. van den Bergh, J.C. Olivier, W.J. Marais, T.L. Grobler, K.J. Wessels, “A search algorithm to meta-optimize the parameters for an extended Kalman filter to improve classification on hypertemporal images”, IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, July 2012.

  7. W. Kleynhans, B.P. Salmon, J.C. Olivier, F. van den Bergh, K.J. Wessels and T.L. Grobler, “Detecting land-cover change using a sliding window temporal autocorrelation approach”, IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, July 2012.

  8. T.L. Grobler, E.R. Ackermann, A.J. van Zyl, W. Kleynhans, B.P. Salmon and J.C. Olivier, “Sequential classification of MODIS time series”, IEEE Interational Geoscience and Remote Sensing Symposium, Munich, Germany, July 2012.

  9. T.L. Grobler, O.M. Smirnov, and C.D. Nunhokee. “Calibration artefacts in KAT-7 data”, General Assembly and Scientific Symposium (URSI GASS), 2014 XXXIth URSI, IEEE, 2014.

  10. T.L. Grobler, O.M. Smirnov, and C.D. Nunhokee. “ALS calibration: analytic expressions for the antenna gains of a two and three element east-west interferometer”, General Assembly and Scientific Symposium (URSI GASS), 2014 XXXIth URSI. IEEE, 2014.

  11. T.L. Grobler, W. Kleynhans and B.P Salmon, “Extracting High-Volume Traffic Routes from AIS Spatial Distribution Maps”, IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan, 2019.

  12. T.L. Grobler, W. Kleynhans and B.P Salmon, “Empirically Comparing Two Dimensionality Reduction Techniques–PCA and FFT: A Settlement Detection Case Study in the Gauteng Province of South Africa”, IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan, 2019.

  13. L. de Lange, D. Ludick and T.L. Grobler, “Detecting failed elements in an arbitrary antenna array using machine learning”, International Conference on Electromagnetics in Advanced Applications (ICEAA), Granada, Spain, 2019.

  14. C.N. Burger, T.L. Grobler and W. Kleynhans, “Discrete Kalman Filter and Linear Regression Comparison for Vessel Coordinate Prediction”, 21st IEEE International Conference on Mobile Data Management (MDM), Versailles, France, 2020.

JOURNAL PUBLICATIONS

  1. T.L. Grobler, A.J. van Zyl, J.C. Olivier, W. Kleynhans, B.P. Salmon and W.T. Penzhorn, “Wu’s algorithm and its possible application in Cryptanalysis”, African Journal of Mathematics and Computer Science Research, vol. 5, no. 1, pp. 1-8, January 2012.

  2. T.L. Grobler, E.R. Ackermann, J.C. Olivier, A.J. van Zyl and W. Kleynhans, “Land-Cover separability analysis of MODIS time-series data using a combined Simple Harmonic Oscillator and a Mean Reverting Stochastic Process”, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 5, no. 3, pp. 857-866, June 2012.

  3. W. Kleynhans, B.P. Salmon, J.C. Olivier, F. van den Bergh, K.J. Wessels, T.L. Grobler, K.C. Steenkamp, “Land cover change detection using autocorrelation analysis on MODIS time series data: detection of new human settlements in the Gauteng province of South Africa”, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 5, no. 3, pp. 777-783, June 2012.

  4. E.R. Ackermann, T.L. Grobler, W. Kleynhans, J.C. Olivier, B.P. Salmon and A.J. van Zyl, “Cavalieri Integration”, Quaestiones Mathematicae, vol. 35, no. 3, pp. 256-296, September 2012.

  5. T.L. Grobler, E.R. Ackermann, A.J. van Zyl, J.C. Olivier, W. Kleynhans and B.P. Salmon, “Using Page’s Cumulative Sum Test on MODIS time-series to detect land-cover changes”, IEEE Geoscience and Remote Sensing Letters, vol. 10, no. 2, pp. 332 – 336, March 2013.

  6. T.L. Grobler, E.R. Ackermann, A.J. van Zyl, J.C. Olivier, W. Kleynhans and B.P. Salmon, “An inductive approach to simulating multispectral MODIS surface reflectance time series”, IEEE Geoscience and Remote Sensing Letters, vol. 10, no. 3, pp. 446 – 456, May 2013.

  7. B.P. Salmon, W. Kleynhans, F. van den Bergh, J.C. Olivier, T.L. Grobler, K.J. Wessels, “Land Cover Change Detection Using the Internal Covariance Matrix of the Extended Kalman Filter Over Multiple Spectral Bands”, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 6, no. 3, pp. 1079 – 1085, June 2013.

  8. B.P. Salmon, W. Kleynhans, F. van den Bergh, J.C. Olivier, W.J. Marais, T.L. Grobler, K.J. Wessels, “Meta-Optimization of the Extended Kalman Filter’s Parameters Through the Use of the Bias Variance Equilibrium Point Criterion”,IEEE Transactions on Geoscience and Remote Sensing, vol. 52, no. 8, pp. 5072 – 5087, August 2014.

  9. T.L. Grobler, C.D. Nunhokee, O.M. Smirnov, A.J. Van Zyl and A.G. de Bruyn. “Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data”, Montly Notices of the Royal Astronomy, vol. 439, no. 4, pp. 4030 – 4047, April 2014.

  10. A. J, Stewart, et al. “LOFAR MSSS: detection of a low-frequency radio transient in 400 h of monitoring of the North Celestial Pole.” Monthly Notices of the Royal Astronomical Society, vol. 456, no. 3, pp. 2321-2342, 2015.

  11. S.J. Wijnholds, T.L. Grobler, O.M. Smirnov, “Calibration artefacts in radio interferometry. II. Ghost patterns for irregular antenna layouts”, Monthly Notices of the Royal Astronomy, vol. 457, no. 3, pp. 2331-2354, 2016.

  12. T.L. Grobler, et al., “Calibration artefacts in radio interferometry–III. Phase-only calibration and primary beam correction.”, Monthly Notices of the Royal Astronomical Society, vol. 461 no. 3, pp. 2975-2992, 2016.

  13. C. D. Nunhokee, et al., “Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme.”, The Astrophysical Journal, vol. 848, no. 1. pp. 47, 2017.

  14. F. Camilo, et al., “Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR.”, The Astrophysical Journal, vol. 856, no. 2, pp. 180, 2018.

  15. J.S. Kenyon, O.M. Smirnov, T.L. Grobler, S.J Perkins. “CUBICAL–Fast Radio Interferometric Calibration Suite Exploiting Complex Optimization”, Monthly Notices of the Royal Astronomical Society, vol. 478, no. 2, pp. 2399-2415, 2018.

  16. T.L. Grobler , G. Bernardi, J.S. Kenyon, A.R Parsons and O.M. Smirnov, et al.,, “Redundant interferometric calibration as a complex optimization problem.” Monthly Notices of the Royal Astronomical Society, vol. 476, no. 2, pp. 2410-2420, 2018.

  17. T.L. Grobler, "Visualization of the Riemann–Stieltjes Integral.", The College Mathematics Journal, vol. 50, no .3, pp.198-209, 2019.

  18. U.M. Sob, H.L. Bester, O.M. Smirnov, J.S. Kenyon and T.L. Grobler, “Radio interferometric calibration using a complex Student’s t-distribution and Wirtinger derivatives”. Monthly Notices of the Royal Astronomical Society, vol. 491, no. 1, pp. 1026-1042, 2020.

  19. A. Ghosh, et al., “Foreground modelling via Gaussian process regression: an application to HERA data.” Monthly Notices of the Royal Astronomical Society, vol. 495, no. 3, pp. 2813-2826, 2020.



STUDENTS

MSc students (graduated) :

  1. Chuneeta Devi Nunhokee (2013-2014). Masters dissertation: Link between ghost artefacts, source suppression and incomplete sky-models. Rhodes University.

  2. Mbou Sob Ulrich Armel (2015-2016): Masters dissertation: Calibration and Imaging with Variable Radio Sources. Rhodes University.

  3. Lydia de Lange (2019): Masters dissertation: Machine learning for antenna array failure analysis. Stellenbosch University.

Hons students (graduated):

  1. 2014: Vuyile Sixaba. Rhodes University.

  2. 2018: Burger Becker, Stephan Luyt. Stellenbosch University.

  3. 2019: Neil Burger, Jason Jackson, Ricardo Luiz and Manfred Habeck. Stellenbosch University.

  4. 2020: Mari-louise Steenkamp, Aidan Elias, Gerhardt Haasbroek, David Macintosh, Christoff van Zyl and Anton van Wyk. Stellenbosh University.

MSc students (current):

Burger Becker, Jason Jackson, Neil Burger, Manfred Habeck, Insight Agbetsiafa.



TEACHING

  1. Introduction to Computer Science 114

  2. Machine Learning 315

  3. Space Science Algorithms 791