Research Interests

My research interests range from focused Electronic Circuit Analysis and Design problems to more Inter-Disciplinary topics in Nonlinear Dynamics, Complex Systems and Circuit modeling for Biology, Biochemistry and Renewable Energy. I am particularly interested in:

Nonlinear Dynamics and Chaos Theory 

With applications to real-time chaotic signal generation, encryption, true random-bit generators, chaotic behavior of biological systems and nonlinear behavior in physics and electrochemistry. Sample publications of this research direction: 

1) Reduced graphene oxide thin film on conductive substrates by bipolar electrochemistry, A Allagui, M Abdelkareem, H Alawadhi, AS Elwakil, Scientific Reports, Nature, 6, 21281, 2016. 

2) On the N-shaped conductance and Hysteretic behavior of contact glow discharge electrolysis, A Allagui, AS Elwakil, Electrochimica Acta, Elsevier, 168, 173-177, 2015. 

3) Clock-driven chaotic pulse-width generators: An overview and demonstration of power supply attack, AS Elwakil, Int. J. Bifurcation & Chaos, World Scientific, 24, (6), 1450079, 2014. 

4) Implementation of an encrypted wireless communication system using nested chaotic maps, AM Abid, Q Nasir, AS Elwakil, Int. J. of Bifurcation and Chaos, World Scientific, 20 (12), 4087-4096, 2010. 

5) Cross-coupled chaotic oscillators and application to random bit generation, S Ozoguz, AS Elwakil, S Ergun, IEE Proceedings Circuits, Devices & Systems, 153 (5), 506-510, 2006. 

6) Construction of classes of circuit-independent chaotic oscillators using passive-only nonlinear devices, AS Elwakil, MP Kennedy, IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 48, (3), 289-307, 2001 (ranked 46 in Top 50 cited papers in IEEE Trans. Circuits & Systems-I). 

Circuit Modeling for Renewable Energy 

Emphasis on providing more accurate and robust models for Ultra High Density capacitors (super-capacitors), Batteries and Fuel Cells. Accurate circuit models that capture the behavior of these elements both in time-domain and frequency-domain is crucial for the development of new energy efficient systems.
Sample publications of this research direction: 

1) Fractional-order models of supercapacitors, batteries and fuel cells: A survey, TJ Freeborn, AS Elwakil, BJ Maundy, Materials for Renewable and Sustainable Energy, Springer, 4 (3), 1-7, 2015. 

2) Simple non-impedance-based measuring technique for supercapacitors, G Tsirimokou, C Psychalinos, AS Elwakil, A Allagui, Electronics Letters, 51 (21), 1699-1701, 2015. 

3) Measurement of super-capacitor fractional-order model parameters from voltage-excited step response, TJ Freeborn, BJ Maundy, AS Elwakil, IEEE J. Emerging and Selected Topics in Circuits and Systems, 3 (3), 1-10, 2013. 

Circuit Modeling For Biology 

Working with a number of researchers, we have been able to propose several novel impedance spectroscopy measurement techniques. These techniques have been successfully applied to extract the electrical properties of fruits and vegetable tissues and can be applied to other biological tissues as well.
Sample publications of this research direction: 

1) Extracting the parameters of the single-dispersion Cole bioimpedance model using a magnitude-only method, BJ Maundy, AS Elwakil, A. Allagui, Computers and Electronics in Agriculture, Elsevier, 119, 153-157, 2015.

2) Cole impedance extractions from the step-response of a current excited fruit sample, TJ Freeborn, BJ Maundy, AS Elwakil, Computers & Electronics in Agriculture, Elsevier, 98, 100-108, 2013.

3) Extracting the parameters of the double-dispersion Cole bioimpedance model from magnitude response measurements, TJ Freeborn, BJ Maundy, AS Elwakil, J. Medical & Biological Engineering & Computing, Springer, 52 (9), 749-758, 2014.

4) Least squares estimation technique of Cole-Cole parameters from step response, TJ Freeborn, B Maundy, AS Elwakil, Electronics letters 48 (13), 752-754, 2012. 

Fundamental Circuit Theory 

Focusing on Two-Port Network design techniques with applications in analog filter design, amplifier design and oscillator design both in discrete and integrated circuits form. Motivating the Two-Port Network Analysis approach is also important for future electronic engineering education since it is the only technique that can accommodate for the extremely complex transistor and circuit models encountered today and enables automated optimization techniques.
Sample publications of this research direction: 

1) Calculating output impedance in linear networks without source or load disconnect: The instantaneous output impedance, AS Elwakil, BJ Maundy, Int. J. Circuit Theory & Applications, Wiley, 44 (1), 98-108, 2016.

2) Single Transistor Active Filters: What is Possible and What is Not, AS Elwakil, BJ Maundy, IEEE Transactions Circuits & Syst-I, 61 (9), 2517-2524, 2014.

3) A new 2 nd ?order allpass filter in 130nm CMOS, P Ahmadi, BJ Maundy, AS Elwakil, L Belostotski,.A Madanayake, IEEE Transactions Circuits & Syst.-II, 63 (3), 249-253, 2016. 

4) On the two-port network analysis of common amplifier topologies, AS Elwakil, BJ Maundy, Int. J. Circuit Theory & Applications, 38 (12), 1087-1100, 2010. 

Fractional-Order Systems 

Fractional-Order Circuits and Systems is an Emerging Interdisciplinary research area. This is an area where mathematics, electrical engineering, biology, chemistry and material science intersect. In the next few years, I would like to focus on establishing an advanced Bio-Electro-Chemistry Characterization Laboratory dedicated to the accurate behavioral and dynamical electrical modeling of material properties and tissue properties for various applications. This would also require developing new instruments that are not readily available in the market.
Sample publications of this research direction: 

1) Compact wide frequency range fractional-order models of human body impedance against contact currents, TJ Freeborn, AS Elwakil, , BJ Maundy, Mathematical Problems in Engineering, (DOI:10.1155/2016/4967937), 2016. 

2) Switched-capacitor fractional-step Butterworth filter design, G Tsirimokou, C Psychalinos, AS Elwakil, Circuits Systems & Signal Processing, Springer, 35 (4), 1377-1393, 2016. 

3) Fractional Step Analog Filter Design, TJ Freeborn, BJ Maundy and AS Elwakil, Book Chapter in `Analog/RF and Mixed Signal Circuit Systematic Design', Chapter 11, 243-267, Springer, 2013. 

4) An expression for the voltage response of a current-excited fractance device based on fractional-order trigonometric identities, AG Radwan, AS Elwakil, Int. J. Circuit Theory & Applications, 40 (5), 533-538, 2012. 

5) Fractional order circuits and systems: An emerging interdisciplinary research area, AS Elwakil, IEEE Circuits & Systems Magazine, 10 (4), 41-50, 2010.

Selected Research Projects

Fractional-Step Analog Filter Design, Co-investigator with Prof. Brent Maundy, University of Calgary, Alberta, Canada (2010-2013) (2 MS students) 

Indirect Measurement of Bio-Impedance, Co-investigator with Prof. Brent Maundy, University of Calgary, Alberta, Canada (2012-2014) (1 PhD student) 

Design of Fractional-order Analog Integrated Circuits, Co-investigator with Prof. Costas Psychalinos, University of Patras, Greece (2014-present) (2 MS students + 1 PhD student) 

Memristor Modeling and Applications, with Dr. Ahmed Radwan, Cairo University/Nile-University, Cairo, Egypt (2013-2015) (1 MS student)

Miniature Hardware for Bio-Impedance Measurement, Co-investigator with Dr. Ahmed Radwan, Cairo University/Nile-University, Cairo, Egypt (2015-present) (1 MS student) 

On the Chaotic Behavior of Electric and Spectral Emission Responses of Contact Glow Discharge Electrolysis, Co-investigator with Dr. Hussain Al-Awadhi and Dr. Anis Allagui, University of Sharjah, Emirates 

Reduced Graphene Oxide-based Double Layer Capacitor for Alternating Current Line Filtering Application, Co-investigator with Dr. Hussain Al-Awadhi and Dr. Anis Allagui, University of Sharjah, Emirates 

Communicating Using Chaos, with Prof. Peter Kennedy, European Union Strategic Research Program INSPECT, 1998-2002 

Realization of Chaotic Oscillators for Integrated Circuits, with Prof. Serdar Ozoguz, Turkish Academy of Science & Istanbul Technical University (ISO/TUBA-GEBIP-2002-1-16), 2003-2005 

Nonlinear Dynamics of Phase Noise in Oscillators, Co-investigator with Prof. Khaled Salama, Intelligent Sensors Lab, Rensselaer Polytechnic Institute, Troy, NewYork (2006-2007)

Research Collaborators

Prof. Brent Maundy (University of Calgary, Alberta, Canada) and his group,
Prof. Serdar Ozoguz (Istanbul Technical University, Turkey) and his group.
Dr. Ahmed G. Radwan (Cairo University, Nile University, Egypt) and his group.
Dr. Khaled Salama (King Abdullah University of Science and Technology KAUST, Saudi Arabia) and his group.
Prof. Costas Psychalinos (University of Patras, Greece) and his group.
Prof. Stephan Gift (University of the West Indies, Trinidad).
Dr. Todd Freeborn (University of Alabama, USA)
Dr. Anis Allagui (University of Sharjah)