Publications

Performance Comparison of the SGM and the SCM in EMC Simulation
Performance Comparison of the SGM and the SCM in EMC Simulation Bai, Jinjun; Zhang, Gang; Wang, Di; Duffy, A. P.; Wang, Lixin Uncertainty analysis methods are widely used in today’s Electromagnetic Compatibility (EMC) simulations in order to take account of the non-ideality and unpredictability in reality and improve the reliability of simulation results. The Stochastic Galerkin Method (SGM) and the Stochastic Collocation Method (SCM), both based on the generalized Polynomial Chaos (gPC) expansion theory, have become two prevailing types of uncertainty analysis methods thanks to their high accuracy and high computational efficiency. This paper, by using the Feature Selective Validation (FSV) method, presents the quantitative accuracy comparison between the foregoing two methods, with the commonly used Monte Carlo Method (MCM) used as the comparison reference. This paper also introduces SCM into the CST software simulation as an example of performing uncertainty analysis. The advantages and limitations of SGM and SCM are discussed in detail in this paper. Finally, the strategy of how to choose between SGM, SCM, and MCM under different situations is proposed in the conclusion section.

Comparison of 3-dimensional datasets by using the generalized n-dimensional (n-D) Feature Selective Validation (FSV) technique
Comparison of 3-dimensional datasets by using the generalized n-dimensional (n-D) Feature Selective Validation (FSV) technique Zhang, Gang; Orlandi, A.; Duffy, A. P.; Wang, Lixin Automatic methods to evaluate the validity of computational electromagnetics computer modeling and simulations have widespread applications. The Feature Selective Validation method is a heuristic technique which has been shown to give broad agreement with visual assessment for 1-dimensional data. As a heuristic technique, extending the dimensionality is an important target for the improvement and development of FSV. One of the major challenges in the development of n-dimensional FSV is the difficulty of obtaining visual assessment results, since the visual comparison of three and higher dimensional data is difficult or even impossible. This paper formulates the comparison of 3-dimensional data based on an established generalized n-dimensional FSV approach. The performance of the approach is investigated by means of the LIVE Video Quality Database which provides subjective scores of 150 distorted videos. A statistical evaluation of the relative performance of FSV and other publicly available full-reference Video Quality Assessment algorithms is presented. Further, parameter tuning is performed to improve the agreement of 3-dimensional FSV results and subjective scores. The proposed approach is finally applied to the self-referenced validation of an electromagnetic simulation model to identify and locate the continuous variation of electric field within a region of space. Collaborative work with Harbin Institute of Technology, China, and the University of L'Aquila, Italy. 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.

Simulation validation of experimental tests for automotive system EMC developmental tests
Simulation validation of experimental tests for automotive system EMC developmental tests Braglia, Giacomo; Duffy, A. P.; Barmada, Sami The development and testing of automotive (sub)systems, particularly for Electromagnetic Compatibility (EMC), usually requires expensive test facilities. This paper describes the use of electromagnetic simulation to demonstrate the level of confidence that can be placed in measurements taken in more general laboratories, thus giving an estimate of the accuracy these facilities can provide. This is important in order to enable/allow more developments in automotive systems from research and development teams without standards compliant test facilities. This is, itself, important because of current developments in all-electric and autonomous vehicles. This paper demonstrates, through the use of full wave simulation, representing a theoretically ideal environment compared with two different approaches to measurement that EMC analysis can be undertaken with a reasonable estimation of accuracy and providing a framework for pre-compliance or developmental testing. Collaborative with the University of Pisa

Peer-to-Peer Live Video Streaming with Rateless Codes for Massively Multiplayer Online Games
Peer-to-Peer Live Video Streaming with Rateless Codes for Massively Multiplayer Online Games Ahmad, Shakeel; Bouras, Christos; Buyukkaya, Eliya; Dawood, Muneeb; Hamzaoui, Raouf; Kapoulas, Vaggelis; Papazois, Andreas; Simon, Gwendal We present a multi-level multi-overlay hybrid peer-to-peer live video system that enables players of Massively Multiplayer Online Games to simultaneously stream the video of their game and watch the game videos of other players. Each live video bitstream is encoded with rateless codes and multiple trees are used to transmit the encoded symbols. Trees are constructed dynamically with the aim to minimize the transmission rate at the source while maximizing the number of served peers and guaranteeing on-time delivery and reliability. ns-2 simulations and real measurements on the Internet show competitive performance in terms of start-up delay, playback lag, rejection rate, used bandwidth, continuity index, and video quality. 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.

Carbon based resistive strain gauge sensor fabricated on titanium using micro-dispensing direct write technology
Carbon based resistive strain gauge sensor fabricated on titanium using micro-dispensing direct write technology Wei, Li-Ju; Oxley, C. H. Carbon based resistive strain gauge sensor suitable for medical implant technology has been directly fabricated on a titanium test-plate using Micro-Dispensing Direct Write (MDDW) technology. A 3.5µm biocompatible dielectric layer of parylene C was initially coated on the titanium test-plate. Commercially available screen-print carbon conductive paste was deposited on the parylene C and cured at 80oC for 3 hours; this was to ensure the physical properties and chemical integrity of the parylene C layer was maintained, whilst meeting the electrical conductivity curing requirements for the carbon tracks. The novel integrated strain sensor was experimentally tested and found to have a gauge factor of 10 making it approximately 5 times more sensitive than a commercially available metal foil strain gauge glued to the same titanium plate. 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.

Comparison of Data with Multiple Degrees of Freedom Utilizing the Feature Selective Validation (FSV) Method
Comparison of Data with Multiple Degrees of Freedom Utilizing the Feature Selective Validation (FSV) Method Zhang, Gang; Duffy, A. P.; Orlandi, A.; Di Febo, D.; Wang, Lixin; Sasse, Hugh G. The feature selective validation method has been shown to provide results that are in broad agreement with the visual assessment of a group of engineers for line, 1-D, data. An implementation using 2-D Fourier transforms and derivatives have been available for some years, but verification of the performance has been difficult to obtain. Further, that approach does not naturally scale well for 3-D and higher degrees of freedom, particularly if there are sizable differences in the number of points in the different directions. This paper describes an approach based on repeated 1-D FSV analyses that overcomes those challenges. The ability of the 2-D case to mirror user perceptions is demonstrated using the LIVE database. Its extension to n-dimensions is also described and includes a suggestion for weighting the algorithm based on the number of data points in a given “direction.” This research is the product of a collaboration between: 1. Harbin Institute of Technology, China 2. De Montfort University, UK 3. University of L'Aquila, Italy “© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Electromagnetic Beam Position Monitoring Model for Particle Energy Linear Accelerator
Electromagnetic Beam Position Monitoring Model for Particle Energy Linear Accelerator Hussain, Sabir; Duffy, A. P.; Sasse, Hugh G. Beam Position Monitoring (BPM) systems are crucial in particle acceleration facilities such as linear and circular accelerators. They are used to maintain a stable and precise beam position to achieve a high level of beam quality. BPMs are also essential for accelerator commissioning, performance optimisation, and fault analysis. Beam functional properties information, such as displacement from the desired axis, information about synchrotron oscillations and betatron movements can be derived from data gathered in BPM systems. Medical linear accelerators (linacs) also employ BPM measurements to ensure optimal generation of treatment radiation. The most common form of analysis is to use a multi-physics based approach and model the beam as a stream of electrons, often involving Monte Carlo implementation – an accurate but computationally expensive approach. This paper presents a simple, but robust and efficient, CST microwave model of the linear accelerator (linac) beam, generated using a simplified approach to beam modeling that uses a conducting filament in place of the particle. This approach is validated by comparison with published work. An approach to BPM using the method applied in this paper opens up opportunities to further analyze the overall design and that of components of particle accelerator systems using commonly available full-wave electromagnetic simulators without the need to include specific particle solutions.

Error-resilient packet-switched mobile video telephony with channel-adaptive rateless coding and early reference picture selection
Error-resilient packet-switched mobile video telephony with channel-adaptive rateless coding and early reference picture selection Dawood, Muneeb; Hamzaoui, Raouf; Ahmad, Shakeel; Al-Akaidi, Marwan, 1959- Providing high-quality video for packet-switched wireless video telephony on handheld devices is a challenging task due to packet loss, varying bandwidth, and end-to-end delay constraints. While many error resilience techniques have been proposed for video transmission over wireless channels, only a few were specifically designed for mobile video telephony. We propose a low-complexity channel-adaptive error resilience technique for packet-switched mobile video telephony, which combines rateless coding, feedback, and reference picture selection. In contrast to previous approaches, our technique uses cumulative feedback at every transmission opportunity and predicts when decoding is likely to fail so that reference picture selection can be triggered at an early stage. Experimental results for H.264 video sequences show that the proposed technique can achieve improvements of 1.64 dB in peak signal-to-noise ratio over benchmark techniques in simulated Long-Term Evolution networks.

Internal Stirring: An Approach to Approximate Evaluation of Shielding Effectiveness of Small Slotted Enclosures
Internal Stirring: An Approach to Approximate Evaluation of Shielding Effectiveness of Small Slotted Enclosures Rusiecki, Andrzej; Aniserowicz, Karol; Duffy, A. P.; Orlandi, A. A new technique for approximate evaluation of a small slotted enclosure shielding effectiveness (SE) is proposed. The enclosure under test is equipped with a built-in, rotating, conductive stirrer, and the SE is determined for discrete angles of the stirrer position. The SE characteristics computed in the frequency domain for the enclosure with the stirrer are compared to those of the enclosure containing different arrangements of printed circuit boards. The paper concludes that the inclusion of an internal stirrer is a potentially beneficial approach to shielding effectiveness testing. The research for this paper was a collaboration between: 1 Plum Ltd., Wspolna 19, Ignatki, 16-001 Kleosin, Poland 2 Bialystok University of Technology, Wiejska 45D, 15-351 Bialystok, Poland 3 De Montfort University, The Gateway, Leicester, LE1 9BH, UK 4 University of L’Aquila, UAq EMC Laboratory, I-67100, L’Aquila, Italy

Estimation of the Bandwidth of Acceptable Crosstalk of Parallel Coupled Ring Resonator Add/Drop Filters
Estimation of the Bandwidth of Acceptable Crosstalk of Parallel Coupled Ring Resonator Add/Drop Filters Mansoor, Riyadh; Sasse, Hugh G.; Al-Asadi, Mohammed Mahdi Mohammed; Ison, Stephen; Duffy, A. P. In this paper, a parallel coupled optical ring resonator filter is studied and the transfer function is derived using the Signal Flow Graph approach to identify the filter performance in terms of crosstalk suppression bandwidth and signal integrity. This paper proposes the use of the Signal Flow Graph (Mason’s rule) approach to determining the filtering characteristics of ring resonators. A commercial electromagnetic simulator is used to validate the analytical model. The modelling of the parallel coupled ring resonator covers the analysis of the out-of-band rejection ratio, crosstalk suppression, loss effect and the effect of coupling coefficients on the crosstalk bandwidth. The good agreement between analytical model results and simulation results suggest that using the derived analytical model provides an accurate starting point for design and analysis and, in doing this, provides a better insight into the signal integrity performance of the filter 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.

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