Browsing by Author "Fear, Elise C."
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Item Open Access An Active-Loaded Phase-Conjugating Rotman Lens for Intelligent Transportation System Backscattering Applications(2018-12-10) Keshavarzian, Pouyan; Okoniewski, Michal M.; Nielsen, Jorgen; Fear, Elise C.; Belostotski, Leonid; Knight, A. M.Retro-directive backscattering is useful for improving link-budget in communication systems, localization and radar cross-section enhancement. Many existing technologies have limitations in terms of overall gain and scalability to higher frequencies. This thesis presents a new active retro-directive array architecture for Intelligent Transportation System applications such as automotive radar. The topology involves designing a phase-conjugating Rotman lens with reflection amplifiers for increased gain. Components of this architecture can be scaled to mm-wave. A reflection amplifier is prototyped and tested to have a maximum gain of 17.1 dB at 5.3 GHz. The circuit is then augmented onto a phase-conjugating Rotman lens. The amplifiers are tuned to ~ 6.5 dB gain at 5.15 GHz and the overall phase-conjugating performance is assessed. The active eleven element lens has a calculated backscattering gain of 19.2-25.4 dB across the scanning range of ±32 ˚ . Keywords: rotman lens, retro-directivity, phase-conjugation, ITSItem Open Access Antenna Evaluation for Ultra-Wideband Microwave Imaging(2010-05-09) Bourqui, Jeremie; Campbell, Mark A.; Williams, Trevor; Fear, Elise C.Numerous antenna designs have been proposed for microwave breast imaging utilizing an ultra-wideband frequency range. The antennas are typically compact, operate in an immersion medium, and have a band covering at least 2–10 GHz. We have developed 3 antennas for our UWB microwave breast imaging system. In this contribution, we compare the performance of the antennas in order to gain insight into the relationship between antenna performance metrics and image quality.Item Open Access Antenna Evaluation for Ultra-WidebandMicrowave Imaging(Hindawi Publishing Corporation, 2010-02-07) Bourqui, Jeremie; Campbell, Mark A.; Williams, Trevor; Fear, Elise C.Item Open Access Contribution of the Purkinje System in Initiation and Maintenance of Arrhythmias(2016) Behradfar, Elham; Vigmond, Edward J.; Nygren, Anders; Fear, Elise C.; Berenfeld, Omer; Davidsen, JörnThe Purkinje system is the conduction network of the heart that facilitates coordinated ventricular contraction and couples to the myocardium at discrete sites called Purkinje-Myocyte Junctions (PMJs). Fine and intricate geometry of the Purkinje system have confined experimental observations, therefore density and distribution of PMJs and Purkinje system contribution during cardiac arrhythmia are unclear. This thesis presents a detailed computer simulation study that highlights the role of the Purkinje system and its interaction with ventricles in arrhythmogenesis and maintenance. Firstly, simulations were performed on a model of rabbit ventricles to explore Purkinje system contributions during ventricular fibrillation. A fractal method for growing the Purkinje system was implemented to allow construction of anatomically realistic Purkinje network and investigation of PMJ density. The role of the Purkinje system in maintaining the arrhythmia was assessed by analyzing reentry dynamics. Results showed that the activation pattern at PMJs had little consistency over time during functional reentry, and a Purkinje system with a higher PMJ density contributed more to reentrant arrhythmia; however, the overall dynamics of sustained reentry did not appear to be significantly affected by Purkinje system complexity and coupling strengths at PMJs. Secondly, the realistic model of the Purkinje system was used to investigate mechanisms through which reduced myocardial coupling, induced by ischemia, modify the interaction between the Purkinje system and ventricular tissue, and affect ventricular excitation pattern. Experimental and modeling results suggest that ischemia-induced closing of gap junctions activates normally quiescent PMJs due to reduced source-sink mismatch and as a result, increased the complexity of activation. Modeling results indicated that a higher number of functional PMJs can speed activation of tissue and compensate for effects of uncoupling in slowing activation of the ventricles. Finally, effects of a potential antiarrhythmic drug, dantrolene, on suppressing delayed afterdepolarizations (DADs) due to Calcium overload were modeled. In ventricular model, rapid pacing promoted triggered activity but only those arising in the Purkinje fibers could generate action potential that propagated throughout the myocardium. According to modeling results, dantrolene could eliminate DAD at the Purkinje level by blocking channels that are only present in the Purkinje system.Item Open Access Deciphering Galactic Magnetism from Polarisation Structures in the Northern Sky(2020-09-23) Ordog, Anna; Brown, Jo C.; Landecker, Thomas L.; Haverkorn, Marijke; Knudsen, David J.; Fear, Elise C.The Milky Way is permeated by magnetic fields ranging from stellar scales up to coherence lengths comparable to the Galactic spiral arms. Determining the Galactic magnetic field (GMF) morphology over a range of spatial scales is necessary in understanding the Galaxy’s formation and evolution, and the role of magnetism in its interactions with other Galactic constituents. While ambient magnetic fields do not radiate, they can affect radiation, the results of which are observable in polarisation via Faraday rotation. The aim of my thesis is to explore three-dimensional GMF properties using new observational techniques. I present my analysis of two complementary radio polarisation datasets: the Synthesis Telescope (ST) data from the Canadian Galactic Plane Survey (CGPS) and the Global Magneto-Ionic Medium Survey (GMIMS) single-antenna data. While the CGPS ST data provide high angular resolution, the broad frequency coverage of GMIMS allows for detection of Faraday complexity along the lines of sight. I found that over large regions in the Galactic disk, the extragalactic (EG) and extended emission (XE) rotation measures (RMs) of the ST trace similar patterns with Galactic longitude, indicative of the two observables probing similar volumes through the disk magnetic field. Modelling reveals basic GMF configurations describing the observed ratio of approximately two between the EG and XE RMs. Examining latitudinal variation in both the EG and XE RMs, I found further evidence of the diagonal orientation of the large-scale magnetic field reversal in the inner Galaxy, in agreement with an earlier study of mine. In GMIMS, I found overall large-scale agreement with previous observations of EG RMs at high latitudes. At low latitudes, differences between the GMIMS and the ST RMs are likely the result of beam depolarisation. I observed Faraday complexity along the line of sight towards a depolarising HII (ionised hydrogen) region, which I show to be useful in probing the surrounding GMF. My experiments in spatial filtering of a combined GMIMS and ST dataset revealed that the large-scale field reversal is obscured in GMIMS by an apparent foreground structure of significant angular size.Item Open Access Design of Multi-band/Wide-band High Efficiency Power Amplifiers(2018-04-18) Li, Xiang; Helaoui, Mohamed; Belostotski, Leonid; Kim, Bumman; Ghannouchi, F. M.; Fear, Elise C.; Alhajj, Reda S.As an important component of the RF front-end in the transmitter, the power amplifier (PA) is used to convert the DC supply power into RF power. As the PA consumes most of the power in the transmitter, minimizing power dissipation of the PA would have a significant effect on the efficiency of the whole system. During recent decades, several works have been done to enhance the PA efficiency. However, there must be a trade-off between efficiency, linearity, gain, output power and bandwidth, which are five crucial attributes of the PA. With the development of the wireless communication system, multiple standards at different frequency bands are highly demanded to be integrated into one system while the increasing data rate requires a wide frequency spectrum and therefore broadband components. The multi-band/wide-band signals also lead to high peak-to-average power ratio. Thus, PAs are required to operate at multi-band/wide-band with high efficiency within a wide output power back-off (OPBO) range. For this reason, this thesis focuses on the PA theory and design method for multi-band, wide-band and wide-OPBO purpose. For the first time, a quad-band impedance inverter with arbitrary frequency ratio is proposed. Based on this impedance inverter, a concurrent quad-band Doherty has been designed at 0.75GHz, 1.75GHz, 2.65GHz and 3.55GHz with efficiency up to 50% at 6dB OPBO. For the first time, this thesis present a new theory for harmonically tuned PAs with maximally flat waveform, named class X PAs. The theory was developed for arbitrary harmonic tuning with arbitrary number of harmonics. The analytic close-form formulas for the voltage and current waveforms are provided. Design space for the Class-X PA with only first three harmonics is derived. To validate the theory, a wide-band PA has been designed with output power above 38dBm, efficiency higher than 70% over an octave bandwidth. The harmonic tuning method is also applied to the outphasing system in order to improve the efficiency. A harmonically tuned class-F outphasing system at 27.1MHz is designed with three third harmonic tuning cases to validate the theory. A harmonically tuned class-F-1 outphasing system at 2.14GHz is designed with efficiency of 68% at 6dB OPBOItem Open Access Engineering Integrity: Using text-matching software in a graduate level engineering course(2019-04-18) Crossman, Katie; Paul, Robyn; Behjat, Laleh; Trifkovic, Milana; Fear, Elise C.; Eaton, Sarah Elaine; Yates, Robin MichaelAcademic misconduct is an unfortunate reality for many post-secondary level educators across disciplines; however, there is currently a paucity of Canadian research on Academic Integrity (Eaton, 2018). This study describes an inter-disciplinary project to investigate the potential for text-matching software to prevent and avoid plagiarism by graduate level engineering students. Conceptual/Theoretical Framework: Our study was informed by the potential for text-matching software to help students understand and avoid plagiarism (Zaza & McKenzie, 2018) and faculty identify instances of plagiarism in an engineering course (Cooper & Bullard, 2014). Although text-matching software has been commercially available since the 1990s, its acceptance within academic contexts is uneven. Reasons for this are manifold, but the most commonly expressed concerns are about a) the punitive nature of the software use; b) the potential for it to be used as a tool for cheating students to “beat the system”, and c) privacy concerns (Savage, 2004). Methodology / Approach: In this project, approved by the institutional REB, assignments submitted in a graduate-level engineering communication course were analyzed using text-matching software, Ithenticate. The first phase of the study involved collecting baseline data from students enrolled in a graduate-level Engineering course (N=132). As per REB protocol, individual results were not shared with the professor or teaching assistants and sharing of aggregated results is not permitted until after February 15, 2019. In our presentation, we share baseline results, as well as outcomes of the second phase of the research, in which the research associate revealed the deception, explained the study, and solicited consent from students to have their next assignment harvested and analyzed. The research associate also introduced the software and provided a workshop on academic integrity including strategies for avoiding plagiarism, such as paraphrasing. Subsequent to these workshops, assignments written by consenting participants were analyzed with Ithenticate to determine whether a reduction in textual similarity occurred. Results / Findings: The results of this study indicate that text-matching software can be useful to students and educators to prevent and identify academic misconduct. This study will add to the growing body of empirical research about academic integrity in Canada and in particular, in engineering contexts.Item Open Access Exploration on Just Noticeable Difference of Amplitude for Surface Shape Perception in a VE through Haptic Interactions(2021-11-25) Huang, Jing; Hu, Yaoping; Fear, Elise C.; Krishnamurthy, DiwakarHuman ability to perceive surface shapes plays a crucial role in understanding their surrounding objects and environments. Although the sense of vision has been employed frequently for virtual shape perception, it is desirable to enhance performance of shape perception in the three-dimensional (3D) virtual environments (VEs) by providing haptic feedback. To explore how well the human ability is to discriminate surface shapes under haptic feedback, the experiment presented in this thesis applied a novel force model, which was created by our research lab, to distinguish four kinds of sinusoidal virtual surfaces, which have various amplitudes differing from a flat surface. The main finding is that Just Noticeable Difference (JND) range of amplitude was around 1.19 - 1.95 mm for distinguishing sinusoidal virtual surfaces from flat ones. This finding quantifies the human ability to discriminate virtual surfaces, and may contribute to fundamental knowledge for creating applications with haptic interactions.Item Open Access Hydration Monitoring using Microwaves: From Modelling and Estimation of Tissue Properties to Validation in Humans(2018-09-21) Garrett, David; Fear, Elise C.; Fear, Elise C.; Okoniewski, Michal M.; Kuo, Arthur D.; Hogan, David B.Dehydration is a prevalent condition which can have profound health consequences. If detected early, it can often be treated by oral fluid replacement. A variety of assessment techniques have been proposed, but none have yet emerged as convenient and accurate indicators. This thesis investigates the use of microwave measurements at the extremities to monitor human hydration, relying on the strong relationship between dielectric properties of tissues and water content. A model describing changes in tissue properties according to dehydration is first developed. We then report an empirical feasibility study in athletes undergoing exercise, demonstrating a relationship between estimated permittivity and weight changes due to water loss. Finally, improved property estimation techniques are introduced which are suitable for reliably detecting changes due to dehydration. This thesis provides a comprehensive initial assessment of how microwave measurements may be used to provide the clinically-demanded method of human hydration assessment.Item Open Access Instrumentation for Functional Brain Monitoring with Intrinsic Optical Signals(2019-12-05) Yu, Linhui; Murari, Kartikeya; Dunn, Jeff F.; Fear, Elise C.; Kiss, Zelma H. T.; Curiel, Laura; Côté, Daniel C.Intrinsic optical signals are widely used in functional brain imaging techniques for measuring hemodynamic parameters, such as oxygen saturation and blood volume. These parameters indicate brain metabolism and serve as an indirect measurement of neural activity. In this thesis, I describe two techniques for hemodynamic monitoring from freely-moving animals. The first technique is single fiber spectroscopy, which enables measurements from a highly-localized volume in deep brain structures. I describe the optical system design for measuring reflectance spectra, Monte Carlo simulations for estimating the sampling volume, phantom experiments for rating the accuracy of hemodynamic parameter quantification, and finally, animal experiments for evaluating system performance in in-vivo experiments. I demonstrate that the single fiber spectroscopic system is capable of measuring spontaneous and stimulus-evoked hemodynamic response through a small diameter multimode fiber from non-line-of-sight brain regions in anesthetized and freely-moving animals. The second system is a miniaturized intrinsic optical sensing system (MiniIOS), a cost-effective, integrated system for measurement from the brain surface. The thesis covers the design and characterization of two versions of MiniIOS, the development of an empirical model for extracting hemodynamic parameters from the measured reflectance, as well as system validation in optical phantoms and animal experiments. The final system has a dimension of 5.5 mm×4.7 mm×1.8 mm and weight of 0.12 g. The system can be powered with a battery and operated as a stand-alone device integrating light source, detector, power supply, data acquisition and storage. Phantom experiments showed that the system was sensitive to both changes in oxygen saturation and blood volume fraction. A pilot animal experiment showed the system can be mounted on the head of a mouse without affecting its movement.Item Open Access Modeling of Antenna Arrays and Mutual Coupling between Array Elements using S-Parameters(2018-03-28) De Silva, Obinamuni Supun Devinda; Belostotski, Leonid; Okoniewski, Michal M.; Fear, Elise C.; Yanushkevich, Svetlana N.An antenna can be modeled as a two-port network using S-parameters. However, having antenna S-parameters are not sufficient for modeling an array of antennas as that requires mutual coupling. This thesis proposes a network model to represent an antenna array including mutual coupling. Using the proposed model, an N-element antenna array can be modeled as a combination of two-port networks to represent each element and an N-port network to represent mutual coupling. In this thesis, the operation of the proposed model is explained and the concept of complete antenna array scattering matrix representation is introduced. Two techniques to calculate mutual coupling S-parameters are presented: primary method using numerical solutions and general method using general expressions. The proposed model was validated with reference to the radiation efficiency and S-parameters between the physically accessible ports using several arrays: various inter-element lengths, varying the number of elements and configurations, and non-identical array elements.Item Open Access Modelling and Design Methodology of High-Efficiency Harmonic Tuned Power Amplifiers for 5G Applications(2018-05-18) Sharma, Tushar; Ghannouchi, Fadhel M.; Helaoui, Mohamed; Kitchen, Jennifer; Alhajj, Reda; Fear, Elise C.; Vyas, Rushi J.Radio Frequency (RF) base station unit moves toward qualification of next generation gallium nitride devices to meet the expectation of fifth generation (5G) wireless communication transmitters. Critical to the enablement and the fulfilment of next-generation network energy efficiency, Power amplifiers (PAs) remain a centre of focus to RF power base station markets. With an immense increase in cellular traffic, the performance of PAs should be constantly improved in terms of power efficiency, linearity, and bandwidth. This thesis focuses on several aspects for enabling high efficiency and bandwidth for small cell PAs for 5G applications. A variety of PA design methodologies have been proposed and implemented to achieve state of the art performance. Innovative input and output controlled harmonic tuned PAs have been presented to enable application of advanced waveform engineering in RF base station products. Harmonic optimization techniques have been proposed for efficiency and bandwidth enhancement of the PA performance. For experimental validation, various prototypes for different peripheries, RF specifications, and targeted performance are fabricated using different technologies. The issues related to bandwidth extension, device reliability, and miniaturization of PA base unit are studied and mitigated. This thesis proposes a novel comprehensive analysis of harmonically tuned amplifiers with respect to input harmonic sensitivity, highlighting the significance of input and output controlled amplifiers and their impact on the linearity of gallium nitride (GaN) based high efficiency PAs. For the first time, this thesis presents class GF and GF-1 amplifiers which have demonstrated outstanding performance by simultaneously tackling both input and output harmonic. In particular, this work demonstrated methods for effective on wafer active load pull that minimizes the amount of time required on the measurement system, and how to directly achieve maximum efficiencies by a combination of fundamental, second, and third harmonic at load and source of the active device. The conventional problem of so-called 2nd harmonic efficiency “null”, has been addressed in this thesis. The study reveals new directions for harmonic load pull and design procedure for high-efficiency PAs, which enables PAs in context of wide bandwidth, high efficiency without compromising the quality of service.Item Open Access A Modular System for Radio Frequency Heating of Hydrocarbon Reservoirs(2019-10-29) Apperley, Thomas; Okoniewski, Michal M.; Nielsen, John; Belostotski, Leonid; Fear, Elise C.; O'Keefe, Kyle P. G.; Bridges, GregRadio frequency (RF) heating is an enhanced oil recovery method with the potential to revolutionize oil sands resource development. In the author's opinion, RF heating currently faces four major practical challenges: heating pattern control, downhole transmission loss, sensitivity to changing reservoir environments and the cost and efficiency of RF generation. This thesis pursues a system concept and laboratory prototypes that can address these issues. The first two challenges can be addressed using a modular system. Sensitivity to the reservoir can be resolved using a single conductor transmission line launcher with two coaxial discontinuities and field quasi-symmetry, which was validated using a frequency-scaled prototype. Power combined switching oscillators can ensure high-efficiency RF generation at high output power, while the use of silicon carbide transistor technology can prospectively reduce cost while providing ruggedness. A new E/Fodd oscillator was devised and a prototype using two power combined oscillators is presented.Item Open Access New Approaches to Measuring and Improving Speech Intelligibility(2020-04-29) Tanaka, Mai; Smith, Michael Richard; Fear, Elise C.; Curiel, Laura; Yanushkevich, Svetlana N.; Sesay, Abu B.Hearing impaired and elderly listeners have trouble understanding speech in the presence of noise, which may be caused by the reduced speech processing ability in the brain. Slowing down the speech that is presented, may provide the listener’s brain more opportunities to process stimuli or collect crucial speech cues. Speech rate modulation algorithms that generate a slowed down version of speech have been suggested as an approach to improve comprehension. However, existing non-uniform speech rate modulation algorithms are difficult to experimentally replicate, often requiring specialized linguistics knowledge of the speech, such as the locations of phonetic elements. Additionally, no previous study has objectively measured intelligibility of rate modulated speech. This thesis proposes new methods for objectively measuring rate modulated speech characteristics through Speech Rate Based Intelligibility Metrics (SRBIM), and for improving speech through SOLely Acoustic Non-Uniform (SOLANU) speech rate modulation. SRBIM was compared to existing metrics in situations where the existing metrics were known to work, involving speech contaminated by various noise types and noise levels, and speech processed through three types of noise reduction algorithms. New and existing metric behaviours were compared by analyzing the correlation and scatter plots between all possible metric pairs. The metrics were also used to rank the performances of the three noise reduction algorithms. Simulations were extended to speech processed through two existing methods and two variants of the proposed SOLANU speech rate modulation algorithm. Analysis through correlation and scatter plots, as well as subjective observations were included. When compared against two of the three existing metrics, SRBIM showed a linear relationship in measuring speech intelligibility of noisy speech and speech processed through noise reduction. Subjective observations showed that clean rate modulated speech was more intelligible than noisy rate modulated speech. SRBIM were the only metrics that reflected the impact of rate modulation on clean speech compared to noisy speech. Thus, SRBIM has potential in measuring speech intelligibility of noisy speech, and speech that had been enhanced through noise reduction or rate modulation. Future research involving human observers with rate modulated speech is recommended to further validate SRBIM to subjective intelligibility scores.Item Open Access Novel Optimization Schemes for Full Waveform Inversion: Optimal Transport and Inexact Gradient Projection(2021-03-09) Li, Da; Lamoureux, Michael P.; Liao, Wenyuan; Lamoureux, Michael P.; Liao, Wenyuan; Braverman, Elena; Innanen, Kristopher A.; Fear, Elise C.; Haber, EldadFull waveform inversion (FWI) is an important seismic inversion technique that provides high-resolution estimates of underground physical parameters. However, high-accuracy inverse results are not guaranteed due to the essential non-convexity characteristics of the FWI problem. This thesis focuses on designing novel optimization schemes for the FWI problem which improve the inverse results. Applying optimal transport (OT) based distances to the FWI problem is popular because they provide additional geometric information. The OT distances are designed for positive measures with equal mass, and the unbalanced optimal transport (UOT) distance can overcome the mass equality condition. A mixed distance is constructed which can also overcome the mass equality condition, and the convex properties for the shift, dilation, and amplitude change are proved. Both UOT distance and the proposed distance are applied to the FWI problem with normalization methods transforming the signals into positive functions. Numerical examples show that the optimal transport based distances outperform the traditional L2 distance in certain cases. The gradient projection methods are often used to solve constrained optimization problems, and the closed-form projection function is necessary since the projection has to be evaluated exactly. A constraint set expanding strategy is designed for the gradient projection methods such that the projection can be evaluated inexactly, which extends the application scope of the gradient projection methods. The convergence analysis is provided with proper assumptions. A priori information of the model is important to improve the inverse result, and an optimization scheme is proposed for incorporating multiple a priori information into the FWI problem. The optimization scheme is a combination of the scaled gradient projection method and a projection onto convex sets algorithm. Also, the L-BFGS Hessian approximation and the above constraint set expanding strategy are used. Numerical examples show that the proposed optimization scheme is flexible for integrating multiple types of constraint sets such as total variation constraint, sparsity constraint, box constraint, and hyperplane constraint into the FWI problem.Item Open Access Performance Evaluation and Improved Permittivity Estimation for a Transmission-based Microwave Imaging System(2019-09-19) Owjimehr, Mehri; Fear, Elise C.; Potter, Michael E.; Belostotski, LeonidMedical microwave imaging, especially breast imaging, is one of the interesting applications of microwave imaging. This imaging technique has potential as a new breast imaging modality as it is low-power, not expensive, and doesn't require tissue compression and inconvenience. Several microwave breast imaging techniques have been introduced and show both promise and limitations. The system of interest in this thesis, the transmission system, appears to have the ability to overcome some of those limitations. Although the transmission system doesn't generate high quality images, it shows reasonable estimation of the average permittivity of the scanned tissue. Phantom and human scans using this system show potential, leading to further investigation. In this thesis, the performance of the transmission system is evaluated in terms of accuracy and resolution. Then one of the biggest challenges in image reconstruction, which is multipath, is investigated. The information extracted from multipath is used to improve the average permittivity estimation and form cross-sectional maps. The proposed methods are also tested on volunteer data and show reasonable results in terms of consistency and tracking changes. Finally, an improved denoising algorithm is proposed to reduce the background noise of the reflected signals in order to prepare them for average permittivity estimation.Item Open Access Polarization Controlled Coherent Anti-Stokes Raman Scattering Microscopy for Determination of Structural Order of the Myelin Sheath(2018-05-17) Brideau, Craig; Stys, Peter K.; Frayne, Richard; Barclay, Paul; Colicos, Michael A.; Fear, Elise C.; Potma, Eric OlafCoherent Anti-Stokes Raman Scattering (CARS) is a laser-scanning microscopy technique that generates a strong label-free signal in lipid. The myelin sheath surrounding nerves is up to 80% lipid, and therefore is an ideal candidate for CARS imaging. The long lipid chains forming the myelin wraps have a directional preference when the myelin is healthy, with CH2 bonds aligned parallel to the axis of the nerve. The optical polarization dependence of the CARS signal can be used to probe the orientation of CH2 bonds in the sheath and determine their nanoscopic orientation. As myelin becomes unhealthy the organization of the lipids begins to loosen from their native organized packing structure. In the early stages this is not visible by conventional microscopy, however polarization-resolved CARS can measure the increasing disorder in the arrangement of the bonds before obvious morphological changes can occur. The degree of disorder is also measured to provide a metric of myelin disorganization in disease models.Item Open Access Synergistic Combination of Microwaves and Acoustic Signals: Towards Improved Breast Imaging(2019-03-01) Omer, Muhammad; Fear, Elise C.; Potter, Michael E.; Sesay, Abu B.; Ferguson, Robert J.; Yu, Alfred C. H.Microwave-based breast imaging techniques offer the convenience of frequently-repeated scans involving no breast compression, non-ionizing radiation, inexpensive scan costs, sensitivity to water content and low-complexity 3D image reconstruction. These benefits are well-suited for its application in breast health monitoring and treatment surveillance for which there is no current established approach. However, limited imaging resolution and target localization accuracy necessitate improvements in image quality for clinical applications. The integration of prior structural information has been seen to benefit microwave-based breast imaging techniques, including microwave tomography (MWT) and microwave radar (MWR)-based approaches. The sources of this structural prior explored in the literature include alternate imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). The ultrasound (US) signals with their short wavelength, low loss and small footprint may also provide this opportunity. The aim of this work is to investigate the possibility of extracting prior information from US signals and integrating this information into radar-based microwave image reconstructions. The synergistic combination of these two modalities improves the imaging focus, resolution, target detection and localization accuracy. In addition, the integration of structural information provides important contextual information for results interpretation as well as enhances the robustness of the method to the variations in breast shape, size, density, number of tumour inclusions and their locations. To support this development process, methods of constructing and generating a repository of realistic numerical breast models have also been presented. These models offer flexibility and reconfigurability to meet varying requirements of developing imaging technologies. They are applied to develop the proposed dual-modality imaging technology, verify its performance and compare it with the state-of-the-art MWR imaging approach.