Professor Alistair Duffy

Job: Professor of Electromagnetics, Associate Dean of Research and Innovation

Faculty: Computing, Engineering and Media

School/department: School of Engineering and Sustainable Development

Research group(s): Advanced Manufacturing Processes and Mechatronics Centre (AMPMC), Centre for Electronic and Communications Engineering (CECE)

Address: De Montfort University, The Gateway, Leicester, LE1 9BH UK

T: +44 (0)116 257 7056

E: apd@dmu.ac.uk

W: https://www.dmu.ac.uk

 

Personal profile

Alistair Duffy is Professor of Electromagnetics, and Associate Dean of Research and Innovation in the Faculty of Technology at De Montfort University, Leicester, UK. He received the Bachelor’s degree in Electrical and Electronic Engineering and an MEng degree from University College, Cardiff, UK, in 1988 and 1989, respectively. After receiving the Master’s degree, he joined the research group of Professors Christopoulos and Benson at Nottingham University. There he worked on experimental validation of numerical modelling and received his PhD in 1993. Dr Duffy completed his professional education in 2004 with an MBA from Open University, UK. He is widely published, with over 200 technical papers and articles, mostly on his research interests of validation of computational electromagnetics; physical layer components, particularly communications cabling, and electromagnetic compatibility testing. 

Dr Duffy has contributed to many successful conferences through refereeing functions or organising committee responsibilities. He currently serves on the Board of Directors of the International Wire and Cable Symposium, which attracts approximately 1,000 delegates annually. He is an Associate Editor for the IEEE Transactions on EMC and an Associate Editor of the ACES Journal. Other professional activities include standards body work in the UK (British Standards Institute) and in the IEEE, where he is currently Chair of the EMC Society's Standards Development and Education Committee (SDECom). He is also the Society’s Global EMC Symposium Coordinator. From 2008 to 2009 he served the IEEE EMC Society as a Distinguished Lecturer. In 2015, Dr Duffy was elected to the grade of IEEE Fellow for the development of validation methods in computational electromagnetics.

Dr Duffy was a Series Editor for undergraduate textbooks published by Butterworth-Heinemann (now part of Elsevier) and SciTech Publishing (now part of the IET) on EMC. He has supervised 20 PhD students during his career.

Publications and outputs

  • Application of probabilistic models for multitone electromagnetic immunity analysis
    dc.title: Application of probabilistic models for multitone electromagnetic immunity analysis dc.contributor.author: Devaraj, Lokesh; Khan, Qazi Mashaal; Ruddle, Alastair R.; Duffy, A. P.; Perdriau, Richard; Koohestani, Mohsen dc.description.abstract: The operational environment of modern electronic systems may include multiple frequency electromagnetic dis- turbances. However, immunity measurements usually employ single frequency continuous waveforms (i.e. single-tones). The performance of two oscillator circuits with different topologies (one simulated and one measured) were used as case studies to in- vestigate immunity to simultaneous single-tone disturbances (i.e. multitones) using probabilistic Bayesian network models. For the multitone analysis, the noisy-OR model was first used to identify the type of causal interactions between simultaneously occurring single-tones. Probabilistic theories derived from the recursive noisy-OR model, which inherits the independence assumptions of the noisy-OR and any known causal dependence between simultaneously occurring single-tones, were then used to predict the probability of higher order multitone failures. For the two case studies, the probability of three-tone failures was estimated using the single-tone and two-tone failure probability values. An improved adaptive recursive noisy-OR model was also proposed to overcome the practical difficulties of obtaining multitone failure probabilities, from either simulations or measurements. dc.description: The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 812790 (MSCA-ETN PETER). The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • On-Line Partial Discharge Localization in Power Cables Based on Electromagnetic Time Reversal Theory - Numerical Validation
    dc.title: On-Line Partial Discharge Localization in Power Cables Based on Electromagnetic Time Reversal Theory - Numerical Validation dc.contributor.author: Ragusa, A.; Sasse, H.; Duffy, A. P. dc.description.abstract: This paper presents the numerical validation of a new on-line location method of partial discharge (PD) in cables of Medium Voltage (MV) power networks based on the electromagnetic time reversal (EMTR) theory. Because PD events are a symptom of cable insulation degradation, PDs localization is a key topic for fault prevention on power networks, increasing their reliability and resilience and to guaranteeing electricity security. A description of the proposed EMTR PD location method is given and its effectiveness and accuracy are analyzed in lines with both homogeneous and inhomogeneous power cables. The accuracy of PD location methods is strongly affected by the distortion of the PD pulses during their propagation on power lines, caused mainly by the skin effect. For this reason, the accuracy of the proposed location method is analyzed using a lossy model of power networks that is able to reproduce PD signals distortion. The model used, realized using the transmission line matrix (TLM) method, is also presented here and theoretically validated. dc.description: This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No 838681.
  • Electromagnetic Time Reversal to Locate Partial Discharges
    dc.title: Electromagnetic Time Reversal to Locate Partial Discharges dc.contributor.author: Ragusa, A.; Sasse, H.; Duffy, A. P. dc.description.abstract: Energy is crucial for the developing world and must be provided when needed to avoid a serious impact on society. Electricity is becoming the increasingly central energy source, strongly demonstrated in the current pandemic, allowing people to remain in contact and to work from home. Electricity security is the power system’s capability to withstand disturbances/ contingencies with an acceptable service disruption and represents a crucial concern for policy decision making at all levels. Usually, service disruption is due to cables’ insulation damage, often caused by partial discharges (PDs) that are localised electrical discharges that partially bridge the insulation between conductors. Since PD is one of the best early-warning indicators of insulation damage, the on-line PD location is the most suitable method to prevent faults, enhancing network reliability. Most location methods are traveling wave-based techniques, using the principle that PD produces electromagnetic waves which are measured at different line points. The difference in the times of their arrival allows the PD localisation. However, their implementation is difficult due to the need for synchronisation and their accuracy is influenced by the PD signals distortion and the presence of electromagnetic interference on networks. This project proposes a new method to locate PDs using the electromagnetic time reversal (EMTR) theory. It is based on the time reversibility of the wave propagation equations and on the spatial correlation property of the EMTR theory that allows refocussing the time-reversed back-propagated PD signals into their original location. The method has been designed in simulation using the Transmission Line Matrix method and experimentally validated on real MV networks. It is able to locate PDs using only one observation point in the harsh electromagnetic environment of real networks with an accuracy of >99%. dc.description: This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No 838681.
  • 3D Simulation of Partial Discharge in High Voltage Power Networks
    dc.title: 3D Simulation of Partial Discharge in High Voltage Power Networks dc.contributor.author: Ragusa, Antonella; Sasse, Hugh G.; Duffy, A. P. dc.description.abstract: Partial discharge (PD) events arise inside power cables due to defects of cable’s insulation material, characterized by a lower electrical breakdown strength than the surrounding dielectric material. These electrical discharges cause signals to propagate along the cable, manifesting as noise phenomena. More significantly, they contribute to insulation degradation and can produce a disruptive effect with a consequent interruption of power network operation. PD events are, therefore, one of the best ‘early warning’ indicators of insulation degradation and, for this reason, the modeling and studying of such phenomena, together with the development of on-line PDs location methods, are important topics for network integrity assessment, and to define methods to improve the power networks’ Electricity Security. This paper presents a 3D model of PD events inside a void in epoxy-resin insulation cables for High Voltage (HV) power networks. The 3D model has been developed using the High Frequency (HF) Solver of CST Studio Suite® software. PD events of a few µs duration have been modelled and analyzed. The PD behavior has been investigated using varying electrical stress. A first study of the PD signal propagation in a power network is described. dc.description: Open access
  • Selection of Dominant Characteristic Modes
    dc.title: Selection of Dominant Characteristic Modes dc.contributor.author: Ghosal, Sandip; De, Arijit; Duffy, A. P.; Chakrabarty, Ajay dc.description.abstract: The theory of characteristic modes is a popular physics based deterministic approach which has found several recent applications in the fields of radiator design, electromagnetic interference modelling and radiated emission analysis. The modal theory is based on the approximation of the total induced current in an electromagnetic structure in terms of a weighted sum of multiple characteristic current modes. The resultant outgoing field is also a weighted summation of the characteristic field patterns. Henceforth, a proper modal measure is an essential requirement to identify the modes which play a dominant role for a frequency of interest. The existing literature of significance measures restricts itself for ideal lossless structures only. This paper explores the pros and cons of the existing measures and correspondingly suggests suitable alternatives for both radiating and scattering applications. An example is presented in order to illustrate the proposed modal method for approximating the shielding response of a slotted geometry. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Measuring the shielding properties of flexible or rigid enclosures for portable electronics
    dc.title: Measuring the shielding properties of flexible or rigid enclosures for portable electronics dc.contributor.author: Duffy, A. P.; Arihilam, E.; Sasse, Hugh G.; Parker, Sarah; Armstrong, R.; Wainwright, N.; Steggles, S.; Thomas, T. dc.description.abstract: Heaviside, in volume 1 of Electromagnetic theory, considered shielding of conducting materials in the form of attenuation. This treatment is still significant in the understanding of shielding effectiveness. He also considered propagation of electromagnetic waves in free-space. What Heaviside (1850–1925) could never have imagined is that 125 years later, there would be devices we know as mobile phones (or cell phones, handies, etc.) with capabilities beyond the dreams of the great science fiction writers of the day like H. G. Wells (1866–1949) or Jules Verne (1828–1905). More than this, that there would be a need for law enforcement agencies, among others, to use electromagnetically shielded enclosures to protect electronic equipment from communicating with the ‘outside world’. Nevertheless, Heaviside’s work is still fundamental to the developments discussed here. This paper provides a review of Heaviside’s view of shielding and propagation provided in volume 1 of Electromagnetic theory and develops that to the design of new experiments to test the shielding of these portable enclosures in a mode-stirred reverberation chamber, a test environment that relies entirely on reflections from conducting surfaces for its operation. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Infra-Red Thermal Measurement on a Low Power Infra-Red Emitter in CMOS Technology
    dc.title: Infra-Red Thermal Measurement on a Low Power Infra-Red Emitter in CMOS Technology dc.contributor.author: Pandey, P.; Oxley, C.; Hopper, Richard; Ali, Z.; Duffy, A. P. dc.description.abstract: This paper presents high temperature characterisation of a novel infra-red (IR) emitter chip based on CMOS technology, using IR thermal microscopy. The performance and reliability of the thermal source is highly dependent on the operating temperature and temperature uniformity across the micro-heater which is embedded within the silicon dioxide membrane. To date, the accuracy of the IR measurement has been limited by the optical transparency of the semiconductor material forming the membrane, which has poor emissivity compared to a black-body source. In this paper, a high emissivity micro-particle sensor is used improve the accuracy of the temperature measurements. IR measurements on the emitter chip were validated with reference to temperature measurements made using an electrical technique where good temperature uniformity across the membrane heater was found. dc.description: The file attached to this record is the author's final peer reviewed version.
  • Review of the Feature Selective Validation Method (FSV). Part II - Performance Analysis and Research Fronts
    dc.title: Review of the Feature Selective Validation Method (FSV). Part II - Performance Analysis and Research Fronts dc.contributor.author: Orlandi, Antonio; Duffy, A. P.; Zhang, Gang dc.description.abstract: After the inclusion of the Feature Selective Validation method into the IEEE Std. 1597.1/2, more and more attention has been paid to performance evaluation and enhancements of this technique as well as broadening of applications. This paper reviews the progresses in these domains by first considering the body of work and the virtual team that is responsible for the method development, and offers conclusions about the validity, the correct implementation and further applications of the Feature Selective Validation technique in other domains besides the classic computational electromagnetics and electromagnetic compatibility. dc.description: The file attached to this record is the author's final peer reviewed version.
  • Using Image Quality Assessment (IQA) Databases to Provide an Appraisal of the Ability of the Feature Selective Validation Method (FSV) to Compare 2-dimensional Datasets
    dc.title: Using Image Quality Assessment (IQA) Databases to Provide an Appraisal of the Ability of the Feature Selective Validation Method (FSV) to Compare 2-dimensional Datasets dc.contributor.author: Zhang, Gang; Orlandi, Antonio; Duffy, A. P. dc.description.abstract: This paper investigates the strengths and drawbacks of the recently developed FSV-2D method. Considering that a subjective benchmark for the validation of 2-dimensional computational electromagnetics data is not available, five datasets with subjective scores, commonly used in image quality assessment, are used. It is found that the FSV-2D prediction is influenced by image type and distortion type. Encouraged by the assessment results, eight parameters of the FSV-2D method are optimized by use of genetic algorithms. It is shown that the optimized FSV-2D method provides better correlation with subjective scores. Good agreement with theoretical analysis for computational electromagnetic data further validates the proposed approach. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
  • Review of the Feature Selective Validation Method (FSV). Part I - Theory
    dc.title: Review of the Feature Selective Validation Method (FSV). Part I - Theory dc.contributor.author: Duffy, A. P.; Orlandi, Antonio; Zhang, Gang dc.description.abstract: It had been just over a decade since the Feature Selective Validation method was proposed in the. As an automated validation method recommended by the IEEE Standard 1597.1/2, the FSV method has gained broad attention in the practice of computational electromagnetics modeling and simulations. This paper reviews the motivation, evolution, enhancements, and criticisms of the method over this time. This aims of this paper are to give a detailed contextualization of the development of the FSV method itself and to discuss the open questions and possible strategies of next generation of automated validation methods. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.


Click here to view a full listing of Alistair Duffy's publications and outputs.

Research interests/expertise

  • Validation of computational electromagnetics. The Feature Selective Valdiation (FSV) method is a product of this research.
  • Communications systems physical layer, particularly communications cabling and antennas.
  • Computational electromagnetics.
  • Electromagnetic measurements, particularly involving the reverberation chamber.
  • Technology strategy, particularly forecasting. 

Courses taught

ENGD2009 Electromagnetics
ENGT5254 Electromagnetic Compatibility
ENGD3011 Electronic and mechanical systems
ENGD2021 Product Introduction and Project Management 

Honours and awards

Honorary member of the Romanian EMC (Electromagnetic Compatibility) Society

Membership of external committees

IEEE EMC Society Board of Directors
IEEE EMC Society Standards Education and Training Committee (Chair)
IWCS Board of Directors
BSi TCT7/-/1 member

Membership of professional associations and societies

Fellow of the IET
Senior Member of the IEEE

Professional licences and certificates

Chartered Engineer

Consultancy work

Data comparison and validation
Structured cabling
EMC testing

Current research students

Currently first supervisor to:

Ahmed Aldabbagh
Hassan fadel
Sabir Hussain
Riyadh Mansoor

Second Supervisor to:

Haitham Adarbah
Clive Collins
Bernd Lehmanski
Mohamed Maricar
Andrew Nicholson

Professional esteem indicators

Associate Editor for the IEEE Transactions on EMC
Editor in Chief for the Applied Computational Electromagnetics Society Newsletter
Series Editor for the IET/SciTech Publishing Series on EMC

Alistair Duffy 051216