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Prof X Xia (Xiaohua)

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Director, National Hub for Postgraduate Programme in Energy Efficiency and Demand Side Management (EEDSM Hub), supported by SANERI

Postal Address

Prof. Xiaohua Xia
Department of Electrical, Electronic & Computer Engineering
University of Pretoria
Pretoria, 0002
South Africa

Tel. +27 12 420-2165
Fax. +27 12 362-5000
E mail: xxia at postino dot up dot ac dot za

Visiting Address

Engineering 1, 14-7
Main campus
Lynnwood Road 2
South Africa


B.Sc(WIHEE, China)
M.Eng(WIHEE, China)
D.Eng(BUAA, China)

Professional Status

Professional Engineer, Engineering Council of South Africa (ECSA)
Certified Measurement and Verification Professional (CMVP), Energy Valuation Organisation (EVO)
National Research Foundation (NRF) rating: A 


Member of the Association of Energy Engineers (AEE)
Fellow of South African Academy of Engineering (SAAE)
Member of the Academy of Science of South Africa (ASSAf)
Fellow IEEE

Professional Service

  • AE for IEEE Transactions on Automatic Control (2011)
  • AE for Automatica (2000–2009)
  • Specialist Editor (Control), African Research Journal: Research Journal of the South African Institute of Electrical Engineers. (was)
  • AE for IEEE CAS-II (was)
  • Chair, TC on Nonlinear Systems, IFAC (2008-2011)
  • Member, Technical Board, IFAC (2008-2011)
  • Past Chair: South African Control Chapter, IEEE
  • Chair: Association for Promoting Scientific and Technological Cooperation between China and South Africa




Electric Circuits I (EBN120)
Electric Circuits II (EBN210)
Control Systems (EBB320)
Energy Systems (EEM 410)


Linear Multivariable Control (EMB732)
Advanced Research Topics in Energy Research (ERT732)

Research Fields and Topics

Energy optimisation and management, Non-linear feedback control, complex systems, sampled-data feedback control, observer design, modelling and control of HIV/AIDS, heavy haul trains, river/dam network systems, delta-modulated feedback systems, chaotic systems

Observability and observation of nonlinear systems, feedback linearization and decoupling of nonlinear systems, dynamic feedback control of nonlinear systems, output feedback control of nonlinear systems, output regulation of nonlinear systems, sampling and simulation of control systems, identifiability of nonlinear (time-delay) systems, periodic orbits arising from delta-modulation and delta-modulated feedback 

– more recent research topics: 

see my personal research pages at

Research Fellow

J. F. Zhang, June 2006 – December 2008

Y. J. Shen, July 2011- November 2011

Postdoctoral Fellows

B. Z. Guo, October 1998–September 1999, now chair professor at Wits, RSA

A. L. Marquez-Martinez, July 2000–January 2001, now CICESE, Mexico

C. P. Li, February 2004–January 2005, now Shanghai University, China

S. Bowong, March 2006–May 2006, now University of Douala, Cameron

Ahmed Mohamed Ahmed Elaiw, August 2007 – July 2008, from Al-Azhar University, (Assiut), Egypt

X. Liang, January 2009 – August 2009, now Tianjing Polytechnic University, China

S. Zhang, November 2008 – November 2009, from Wuhan University, China

D. Wei, January 2009 – June 2011

Martin Siewe Siewe July 20111- November 2011

Hui Yu, May 2011- April 2012

M. Xiao, September 2012 - August 2013

Z. Wu, current

B. Zhu, current

Q. Cheng, current


T. C. Song (MEng, co-supervised with L. Linde, degree obtained in 2003)

R. Filter (MEng, degree obtained in 2004)

M-S. Chou (MEng, degree obtained in 2005)

M. Jeffrey (PhD, co-supervised with IK Craig, degree obtained in 2006)

X-T. Zhuan (PhD, degree obtained in 2007)

E. du Toit (MEng, degree obtained in 2008)

X. Liang (PhD, degree obtained in 2009)

J. van Staden (MEng, degree obtained in 2010) 

W. Badenhorst (MEng, degree obtained in 2010)

H. Zhang (MEng, co-supervision with J. Zhang, degree obtained in 2011)

U.E. Ekpenyong (MEng, co-supersion with J. Zhang, degree obtained in 2011)

M. Strempel (MEng, co-supervision with F. Camisani)

O. J. Botai (MEng)

Y. Li (PhD, degree obtained in 2014) 

M. Nikkhah Mojdehi (PhD)

X. Ye (PhD)

N. Wang (PhD)

T. Mathaba (PhD)

M. S. Essien (MEng, degree obtained in 2013)

E. Malatji (MEng, degree obtained in 2014)

Z. Olinga (MEng)

D. Sethlaolo (PhD)

P. Gumbi (PhD)

H. Tazvinga (PhD)

L. Zhang (PhD)

U.E. Ekpenyong (PhD)

N. NWulu (PhD)

P. Numbi (PhD)

S. Sichilalu (PhD)

C. Meng (PhD)

Y. Fan (PhD)

J. Mei (PhD)

E. Murimi (PhD)

A. Chatterjee (MEng)

H. Carstens (MEng, degree obtained 2014)

T. Hlalele (MEng, degree obtained in 2014)

M. Michael (MEng)

S. Ntsaluba (MEng)

M. Chennells (MEng)

__Publications after joining University of Pretoria__

*  See: for an updated list 

[89] P. Miao, Y. Shen and X. Xia, Finite time dual neural networks with a tunable activation function for solving quadratic programming problems and its application, Neurocomputing 143 (2014), pp 80-89. 

[88] B. Wang, X. Xia, and J. Zhang, A multi-objective optimization model for the life-cycle cost analysisand retrofitting planning of buildings, Energy and Buildings 77 (2014) 227-235.

[87] T. Mathaba, X. Xia, and J. Zhang, Analysing the economic benefit of electricity price forecast in industrial load scheduling, Electric Power Systems Research 116 (2014) 158-165. 

[86] D. Setlhaolo, X. Xia and J. Zhang, Optimal scheduling of household appliances for demand response, Electric Power Systems Research 116 (2014) 24-28. 

[85] H. Carstens, X. Xia, and X. Ye, Improvements to longitudinal Clean Development Mechanism sampling designs for lighting retrofit projects, Applied Energy 126 (2014) 256-265. 

[84] B.P. Numbi, J. Zhang, and X. Xia, Optimal energy management for a jaw crushing process in deep mines, Energy 68 (2014) 337-348. 

[83] S. Qu, X. Xia and J. Zhang, Dynamics of discrete-time sliding-mode-control uncertain systems with a disturbance compensator, IEEE Transactions on Industrial Electronics, vol. 61, no. 7, July 2014, pp. 3502-3510. 

[82] Y. Shen and X. Xia, Adaptive parameter estimation for an energy model of belt conveyor with DC motor, Asian Journal of Control, vol. 16, no. 3, pp. 1-11, May 2014. 

[81] L. Zhang, X. Xia and J. Zhang, Improving energy efficiency of cyclone circuits in coal beneficiation plants by pump-storage systems, Applied Energy119 (2014) 306-313. 

[80] K. M. Abo-Al-Ez, A. Elaiw and X. Xia, A dual-loop model predictive voltage control/sliding-mode current control for voltage source inverter operation in smart microgrids, Electric Power Components and Systems, 42(3-4): 348-360, 2014.

[79] X. Ye, X. Xia and J. Zhang, Optimal sampling plan for clean development mechanism energy efficiency lighting projects, Applied Energy 112 (2013) 1006-1015. 

[78] N. Wang, J. Zhang and X. Xia, Desiccant wheel thermal performance modeling for indoor humidity optimal control, Applied Energy 112 (2013) 999-1005. 

[77] A. M. Elaiw, X. Xia and A. M. Shehata, Hybrid DE-SQP method for solving combined heat and power dynamic economic dispatch problem, Mathematical Problems in Engineering, Volume 2013, Article ID 982305, 7 pages, /

[76] H. Yu, Y. Shen and X. Xia, Adaptive finite-time consensus in multi-agent networks, Systems and Control Letters 62 (2013) 880-889. 

[75] H. Tazvinga, X. Xia and J. Zhang, Minimum cost solution of photovoltaic-diesel-battery hybrid power systems for remote consumers, Solar Energy 96 (2013) 292-299.

[74] N. Wang, J. Zhang and X. Xia, Energy consumption of air conditioners at different temperature set points, Energy and Buildings 65 (2013) 412-418.

[73] AM Elaiw, X. Xia and AM Shehata, Hybrid DE-SQP and hybrid PSO-SQP methods for solving dynamic economic emission dispatch problem with valve-point effects, Electric Power Systems Research, 103 (2013) 192-200. 

[72] X. Zhuan and X. Xia, Development of efficient model predictive control strategy for cost-optimal operation of a water pumping station, IEEE Transactions on Control Systems Technology, VOL. 21, NO. 4, JULY 2013, pp. 1449-1454. 

[71] X. Xia and J. Zhang, Mathematical description of measurement and verification of energy efficiency improvement, Applied Energy 111 (2013) 247-256. 

[70] Y. Li, X. Xia and Y. Shen, A high-gain-based global finite-time nonlinear observer, International Journal of Control, vol. 86, no. 5, 2013, pp. 759-767. 

[69] A. M. Elaiw, X. Xia and A. M. Shehata, Minimization of fuel costs and gaseous emissions of electric power generation by model predictive control, Mathematical Problems in Engineering, vol. 2013, article ID 906958, 15 pages. 

[68] Y. Li, Y. Shen and X. Xia, Global finite-time observers for a class of nonlinear systems, Kybernetika 49 (2013), no. 2, pp. 319-340. 

[67] E. Malatji, J. Zhang and X. Xia, A multiple objective optimisation model for building energy efficiency investment decision, Energy and Buildings 61 (2013) 81-87. 

[66] X. Zhuan and X. Xia, Optimal operation scheduling of a pumping station with multiple pumps, Applied Energy 104 (2013) 250–257. 

[65] X. Ye, X. Xia, J. Zhang and Y. Chen, Effects of trends and seasonalities on robustness of the Hurst parameter estimators, IET Signal Processing, 2012, Vol. 6, Iss. 9, pp. 849–856. 

[64] A. M. Elaiw, X. Xia and A. M. Shehata, Dynamic economic dispatch using hybrid DE-SQP for generating units with valve-point effects, Mathematical Problems in Engineering Volume 2012, Article ID 184986, 10 pages, doi:10.1155/2012/184986. 

[63] H. Yu and X. Xia, Adaptive consensus of multi-agents in networks with jointly connected topologies, Automatica 48 (2012) 1783-1790. 

[62] M. Siewe Siewe and X. Xia, Nonlinear dynamics and small damping signal control of chaos in a model of flow-induced oscillations of cylinders, Mechanics Research Communications 46 (2012) 8-14. 

[61] U.E. Ekpenyong, J. Zhang and X. Xia, An improved robust model for generator maintenance scheduling, Electric Power Systems Research 92 (2012) 29-36. 

[60] X. Xia, J. Zhang and W. Cass, Energy management of commercial buildings - A case study from a POET perspective of energy efficiency, Journal of Energy in Southern Africa, Vol 23, No 1, February 2012, 23-31.

[59] H. Zhang, X. Xia and J. Zhang, Optimal sizing and operation of pumping systems to achieve energy efficiency and load shifting, Electric Power Systems Research 86 (2012) 41-50. 

[58] A. M. Elaiw, X. Xia and A. M. Shehata, Application of model predictive control to optimal dynamic dispatch of generation with emission limitations, Electric Power Systems Research 84 (2012) 31-44.

[57] A. J. van Staden, J. Zhang and X. Xia, A model predictive control strategy for load shifting in a water pumping scheme with maximum demand charges, Applied Energy 88 (2011) 4785 – 4794.

[56] X. Xia and J. Zhang, Modelling and control of heavy-haul trains, IEEE Control Systems Magazine, vol. 31, no. 4, August 2011, 18 - 31. 

[55] X. Xia, J. Zhang and A. Elaiw, An application of model predictive control to the dynamic economic dispatch of power generation, Control Engineering Practice 19 (2011) 638–648.

[54] S. Zhang and X. Xia, Modeling and energy efficiency optimization of belt conveyors, Applied Energy 88 (2011) 3061–3071.

[53] W. Badenhorst, J. Zhang and X. Xia, Optimal hoist scheduling of a deep level mine twin rock winder system for demand side management, Electric Power Systems Research 81 (2011) 1088–1095.

[52] Hongyu Miao, Xiaohua Xia, Alan S. Perelson and Hulin Wu, On Identifiability of Nonlinear ODE Models and Applications in Viral Dynamics, SIAM REVIEW, Vol. 53, No. 1, pp. 3–39, 2011.

[51] J. Zhang and X. Xia, A model predictive control approach to the periodic implementation of the solutions of the optimal dynamic resource allocation problem, Automatica 47 (2011) 358–362.

[50] J. Zhang, C. H. Moog, and X. Xia, Realization of multivariable nonlinear systems via the approach of differential forms and differential algebra, Kybernetika, Vol. 46 (2010), No. 5, pp. 799-830.

[49] X. Xia and J. Zhang, Geometric steady states of nonlinear systems, IEEE Transactions on Automatic Control, Vol. 55, No. 6, June 2010, pp. 1448-1454. 

[48] X. Zhuan and X. Xia, Fault-tolerant control of heavy-haul trains, Vehicle System Dynamics, Vol. 48, No. 6, June 2010, 705–735. 

[47] X. Xia and A. M. Elaiw, Optimal dynamic economic dispatch of generation: A review, Electric Power Systems Research 80 (2010) 975–986. 

[46] S. Zhang and X. Xia, Optimal control of operation efficiency of belt conveyor systems, Applied Energy 87 (2010) 1929–1937.

[45] A.M. Elaiw and X. Xia, HIV dynamics: Analysis and robust multirate MPC-based treatment schedules, J. Math. Anal. Appl. 359 (2009) 285–301.

[44] X. Zhuan, G. Zheng, and X. Xia, A modelling methodology for natural dam-river network systems, Control Engineering Practice 17 (2009) 534–540. 

[43] A. Middelberg, J. Zhang and X. Xia, An optimal control model for load shifting – With application in the energy management of a colliery, Applied Energy 86 (2009) 1266- 1273. 

[42] Y. Shen and X. Xia, Semi-global finite-time observers for nonlinear systems, Automatica 44 (2008) 3152-3156. 

[41] X. Liang, J. Zhang and X. Xia, Adaptive synchronization for generalized Lorenz systems, IEEE Transactions on Automatic Control Vol. 53, No. 7, August 2008, pp. 1740-1746. 

[40] X. Liang, J. Zhang and X. Xia, Improving the security of chaotic synchronization with a Delta-modulated cryptographic technique, IEEE Transactions on Circuits and Systems II vol. 55(7), July 2008, 680-684.

[39] S. Bowong and X. Xia, Robust synchronization of a class of nonlinear systems: applications to chaotic coupled electromechanical systems, Journal of Vibration and Control 14(4): 531-551, 2008. 

[38] X. Xia, G. Chen, R. Gai and AS. Zinober, Periodicity in Delta-modulated feedback control, J Control Theory Appl 2008 6 (1) 37-44.

[37] X. Xia and J. Zhang, Geometric characterization on the solvability of regulator equations, Automatica 44 (2008) 445-450. 

[36] X. Zhuan and X. Xia, Speed regulation with measured output feedback in the control of heavy haul trains, Automatica 44 (2008) 242-247. 

[35] X. Zhuan and X. Xia, Optimal scheduling and control of heavy haul trains equipped with electronically controlled pneumatic braking systems, IEEE Transactions on Control Systems Technology Vol. 15, No. 6, 1159-1166, NOVEMBER 2007. 

[34] Frank Doyle, Lois Jovanovic, Dale Seborg, Robert S. Parker, B. Wayne Bequette, Annah M. Jeffrey, Xiaohua Xia, Ian K. Craig, Thomas McAvoy, A tutorial on biomedical process control, Journal of Process Control 17 (2007) 571-594. IV. Structured treatment interruptions: A control mathematical approach to protocol design, contributed by Annah M. Jeffrey, Xiaohua Xia, Ian K. Craig. 

[33] X. Xia, Periodic orbits arising from two-level quantized feedback control, Chaos, Solitons & Fractals 33 (2007) 1339-1347. 

[32] X. Xia and G. Chen, On delta-modulated control: A simple system with complex dynamics, Chaos, Solitons & Fractals, 33 (2007) 1314-1328. 

[31] X. Xia, Modelling of HIV infection: Vaccine readiness, drug effectiveness and therapeutical failures, Journal of Process Control 17 (2007) 253 - 260.

[30] M. Chou and X. Xia, Optimal cruise control of heavy-haul trains equipped with electronically controlled pneumatic brake systems, Control Engineering Practice 15 (2007) 511-519. 

[29] M. Chou, X. Xia and C. Kayser, Modelling and model validation of heavy-haul trains equipped with electronically controlled pneumatic brake systems, Control Engineering Practice 15 (2007), 501-509. 

[28] R. Gai, X. Xia and G. Chen, Complex dynamics of systems under Delta-modulated feedback, IEEE Transactions on Automatic Control vol. 51, no. 12, 1888-1902, December 2006. 

[27] R. Gai, G. Chen and X. Xia, Global dynamics of unbalanced Delta-modulated feedback-controlled discrete-time systems, Dynamics of Continuous, Discrete and Impulsive Systems Series B: Applications & Algorithms vol. 13, 635-679, 2006.

[26] X. Zhuan and X. Xia, Cruise control scheduling of heavy haul trains, IEEE Transactions on Control Systems Technology vol. 14, no. 4, 757–766, JULY 2006. 

[25] X. Xia and A. S. I. Zinober, \Delta-modulated feedback in discretization of sliding mode control, Automatica vol. 42 771–776, 2006.

[24] J. Zhang, X. Xia, and C. H. Moog, Parameter identifiability of nonlinear systems with time-delay, IEEE Transactions on Automatic Control vol. 51, no. 2, 371–375, February 2006. 

[23] X. Xia, G. Chen and R. Gai, Control Lyapunov modes of linear control systems, The Transactions of the SA Institute of Electrical Engineering vol. 96, no. 4, 273-278, December 2005. 

[22] AM. Jeffrey and X. Xia, Identifiability of HIV/AIDS models, in: DETERMINISTIC AND STOCHASTIC MODELS OF AIDS AND HIVWITH INTERVENTION Chapter 11, H. Wu and W. Y. Tan (Eds), World Scientific Publications, Singapore 2005.

[21] A. M. Jeffrey, X. Xia and I. K. Craig, A viral load time response analysis to anti-retroviral therapy, The Transactions of the SA Institute of Electrical Engineering vol. 96, no. 3, 234-239, September 2005. 

[20] R. A. Filter, X. Xia and C. M. Gray, Dynamic HIV/AIDS parameter estimation with application to a vaccine readiness study in Southern Africa, IEEE Transactions on Biomedical Engineering vol. 52, no. 5, 284-291, May 2005. 

[19] C. M. Gray, C. Williamson, H. Bredell, A. Puren, X. Xia, R. Filter, L. Zijenah, H. Cao, L. Morries, E. Vardas, M. Colvin, G. Gray, J. McIntyre, R. Musonda, S. Allen, D. Katzenstein, M. Mbizo, N. Kumwenda, T. Taha, S. A. Karim, J. Flores and H. W. Sheppard, Viral dynamics and CD4+ T celll counts in subtype C human immunodeficiency virus type 1-infected individuals from Southern Africa, Aids Research and Human Retroviruses vol. 21, no. 4, 285-291, 2005. 

[18] I. Craig and X. Xia, Can HIV/AIDS be controlled? IEEE Control Systems Magazine vol, 25, no. 2, 80–83, February 2005. 

[17] T. C. Song, L. P. Linde and X. Xia, A new WCDMA transmit power control technique, The Transactions of the SA Institute of Electrical Engineeringvol. 96, no. 1, 45-55, January 2005. 

[16] C. Li and X. Xia, On the bound of the Lyapunov exponents for continuous systems, Chaos vol. 14, no. 3, 557-561, September 2004. 

[15] X. Xia, A. S. I. Zinober, Periodic orbits from Delta-modulation of stable linear systems, IEEE Transactions on Automatic Control vol. 49, no. 8, 1376-1380, August 2004. 

[14] I.K. Craig, X. Xia, and J.W. Venter, Introducing HIV/AIDS education into the electrical engineering curriculum at the University of Pretoria, IEEE Transactions on Education vol. 47, no. 1, 65-73, February 2004.

[13] X. Xia, R. Gai and G. Chen, Periodic orbits arising from Delta-modulated feedback control, Chaos, Solitons & Fractals vol. 19, 581-595, 2004. 

[12] X. Xia, Estimation of HIV/AIDS parameters, Automatica vol. 39, 1983-1988, 2003. 

[11] X. Xia, Zero polyhedral cones, Applied Mathematics Letters vol. 16, 961-966, 2003. 

[10] M. Jeffrey, X. Xia, I.K. Craig, When to initiate HIV therapy: a control theoretic approach, IEEE Transactions on Biomedical Engineering vol. 50, 1213-1220, 2003. 

[9] X. Xia, C. H. Moog, Identifiability of nonlinear systems with applications to HIV/AIDS models, IEEE Transactions on Automatic Control vol. 48, no. 2, pp. 330-336, February, 2003. 

[8] R. Pothin, C. H. Moog and X. Xia, Disturbance decoupling of nonlinear MISO systems by static measurement feedback, Kybernetika vol. 38, No.5, 601-608, 2002. 

[7] X. Xia, LA. Marquez, P. Zagalak and CH. Moog, Analysis of nonlinear time-delay systems using modules over non-commutative rings, Automatica vol. 38, pp. 1549-1555, 2002. 

[6] X. Xia, C. H. Moog and R. Pothin, Extended output injection and output feedback i/o linearization, Electronics Letters vol. 38, no. 4, pp. 200-202, 2002. 

[5] X. Xia, Well-posedness of piecewise-linear systems with multiple modes and multiple criteria, IEEE Transactions on Automatic Control vol. 47, no. 10, 1716-1720, October 2002. 

[4] X. Xia, Global frequency estimation using adaptive identifiers, IEEE Transactions on Automatic Control vol. 47, no. 7, 1188-1193, July 2002. 

[3] R. Pothin, C. H. Moog and X. Xia, Stabilization of a series DC motor by dynamic output feedback, in: NONLINEAR CONTROL IN THE YEAR 2000VOL 2, LECTURE NOTES IN CONTROL AND INFORMATION SCIENCES 259: 257-263 2001, A. Isidori, F. Lamnabhi-Lagarrigue and W. Respondek (Eds), Springer, London. 

[2] B. Guo, X. Xia, F. R. Camisani-Calzolari and I. K. Craig, A semi-discrete approach to modeling and control of the continuous casting process, Steel Research vol. 71, 220-227, 2000. 

[1]X. Xia and C. H. Moog, Disturbance decoupling of nonlinear systems by output feedback, IEEE Transactions on Automatic Control vol. 44, 1425-1429, 1999.

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