<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #585858} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #6f6f6f} p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #424242} span.s1 {color: #424242} span.s2 {color: #6f6f6f} span.s3 {color: #585858} span.s4 {color: #8d8d8d}</p> <p>Auditory nerve fibers in an ear with outer hair cell damage can be conceptualized as filters having a broadened frequency response area, a shallower phase response and a shorter group delay with respect to a healthy fiber, particularly at low stimulus presentation levels. As well, the presence of inner hair cell damage requires increased stimulus presentation levels for restoration of fiber discharge rates, which results in broad auditory filters with shallow phase response and short group delay. As a consequence, the discharge times in the impaired ear in response to a tone stimulus are more coincident across a population of fibers with a range of characteristic frequencies. This behaviour resembles the spatiotemporal response pattern in a healthy auditory periphery in response to loud stimuli and has been postulated as a potential correlate to loudness recruitment. Commercial hearing aids do not address any changes in the phase characteristics of impaired auditory nerve fibers.</p> <p>The present study evaluates the potential for correction of the altered temporal p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #585858} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #6f6f6f} span.s1 {color: #6f6f6f} span.s2 {color: #424242} span.s3 {color: #585858} span.s4 {font: 11.0px Times} span.s5 {font: 11.0px Times; color: #585858} span.s6 {font: 11.0px Times; color: #8d8d8d} span.s7 {color: #8d8d8d} span.s8 {font: 11.0px Times; color: #6f6f6f} span.s9 {font: 11.0px Times; color: #a1a1a1}</p> <p>relationships in the neural firing pattern of the impaired ear by a hearing aid. An improved version of the spatiotemporal pattern correction (SPC) scheme (Shi et al., 2006) is presented, which measures the instantaneous difference in group delay between a bank of model healthy and impaired auditory nerve fibers and inserts the corresponding delays into an analysis-synthesis gammatone filterbank in t he hearing aid. Human testing of the original processing scheme showed that listeners preferred unprocessed sounds over processed sounds and that no systematic improvement in speech intelligibility was provided by the processed speech (Shi et al. , 2006; Calandruccio et al. , 2007). However, no computational analysis of t his scheme was reported and no attempts were made to restore synchrony to the formants of voiced speech in the neural response. To address this issue, the current work pre-processes SPC with an updated version of the multiband and improved, contrast-enhanced frequency shaping (MICEFS) algorithm (Harte et al. , 2006) to restore formant synchrony.</p> <p>These processing schemes are evaluated with a computational model of the auditory p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #6f6f6f} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #585858} span.s1 {color: #585858} span.s2 {color: #424242} span.s3 {color: #8d8d8d} span.s4 {color: #6f6f6f}</p> <p>periphery (Zilany and Bruce, 2006, 2007) in response to a synthesized vowel for a</p> <p>number of hearing loss types. Analysis indicates that SPC disrupts the spatiotemporal</p> <p>response, but some synchrony can be preserved if the signal is pre-processed with</p> <p>MICEFS and if the SPC delays are applied at the appropriate time. There are some technical problems associated with the processing scheme discovered in this study that remain unresolved. These include: i) a non-fiat frequency response through the analysis-synthesis filterbank due to changes in the relative temporal alignment of filterbank channels, ii) group delay corrections that are based on potentially incorrect frequencies due to the spread of synchrony in audit ory nerve responses, and iii) frequency modulations in the processed signal creat ed by the insertion of time-varying delays, which results in noise that is audible to normal listeners. Despite these issues, evaluation with an error metric derived from auditory nerve response cross-correlations shows that this processing scheme improves some features of the spatiotemporal response, even though it degrades others.</p> / Master of Applied Science (MASc)

<p>During the past two decades, there has been an increasing demand for medical image registration. Deformable image registration has a great importance, because the majority of the registration applications deal with the conditions in which the rigid assumption would not create accurate results. Soft tissue organs (e.g. liver, kidney, and prostate) can change in shape during an intervention. Therefore, a sophisticated registration essentially needs to take into account the geometrical deformations.</p> <p>In this thesis, we study the problem of deformable liver image registration between Magnetic Resonance (MR) and Ultrasound (US) images of the liver. In our approach, a tracking system is proposed to acquire and rigidly register a 2D US image <em>(I_us)</em> with the previously taken MR volume. According to the information obtained from the tracking system, a 2D MR image (<em>I_MR</em>) is reconstructed as the match of Ius. Mutual information is chosen as the similarity measure between the two modalities in our rigid registration problem. A search optimization problem on the registration parameters is then performed, to provide us with a fine tuned reconstructed <em>I_MR</em>.</p> <p>Our proposed strategy begins with visually identifying corresponding anatomical landmarks on <em>I_us</em>and <em>I_MR</em>. These landmarks are the inputs of the two proposed methods of deformation in this thesis. The first method, Finite Element Modeling (FEM) approach, produces the deformed images based on the linear elasticity and the static analysis assumptions. This method uses the positions of landmarks to solve a linear system of equations, in order to generate the final deformations of the MR images. The second method of deformation is the Moving Least Squares (MLS). To the best of our knowledge, MLS has never been used in medical image registration. This technique analytically solves a number of least squares problems to find the local rigid transformations. Applying these local rigid transformations on the MR volume creates the deformations throughout the MR images.</p> <p>In our experiments, Root Mean Square Target Registration Error (RMS TRE) is used as the quantitative measure for the evaluation of performance. FEM-based method produces the best result with an RMS TRE of 7.2mm, while MLS-based method creates an RMS TRE of 8.9mm. According to the literature, an accuracy of 7.2mm is acceptable for most intra-operative abdominal procedures, particularly those involving the liver. The drawback of FEM-based method is its higher computational complexity. Our implementation of the MLS-based method could be executed at least 20 times faster than that of the FEM-based method. Therefore, in applications, where the accuracy is critical, FEM-based method should be used. The MLS-based method is more suitable of the applications demanding higher speed or a parallel implementation of the FEM-based method can solve the computation speed problem.</p> / Master of Applied Science (MASc)

<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #2d2d2d} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #4d4d4d} p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Times; color: #626262} span.s1 {color: #4d4d4d} span.s2 {color: #2d2d2d} span.s3 {color: #141414} span.s4 {color: #aaaaaa} span.s5 {color: #626262} span.s6 {color: #797979} span.s7 {font: 11.5px Helvetica}</p> <p>The inverse source problem of electromagnetics for homogeneous background medium</p> <p>is investigated numerically using the Transmission-Line Matrix (TLM) method. By transforming all sources and fields into their equivalent link impulses inside a TLM computational domain, a discrete linear inversion formulation is developed. Our approach solves for the unknown source distribution inside a given source region using the near-field measurements on its boundary. Unlike the conventional frequency domain treatments, both our source solution and the field measurements are obtained in the time domain. The non-uniqueness of the inverse source problem is addressed by addit ionally imposing a smoothness prior constraint. First-order time and spatial derivatives of the source distribut ion are minimized. The source reconstruction algorithm introduced in this thesis is illustrated through various two-dimensional numerical examples. It is also shown that our algorithm is robust against the noise from the boundary field measurements.</p> / Master of Applied Science (MASc)

<p>Seizure is the result of excessive electrical discharges of neurons, which usually develops synchronously and happens suddenly in the central nervous system. Clinically, it is difficult for physician to identify neonatal seizures visually, while EEG seizures can be recognized by the trained experts. Usually, in NICUs, EEG monitoring systems are used instead of the expensive on-site supervision. However, it is time-consuming to review an overnight recording, which motivates the researchers to develop automated seizure detection algorithms.</p> <p>Although, there are few detection algorithms existed in the literature, it is difficult to evaluate these mathematical model based algorithms since their performances vary significantly on different data sets. By extending our previous results on multichannel information fusion, we propose a distributed detection system consisting of the existing detectors and a fusion center to detect the seizure activities in the newborn EEG. The advantage of our technique is that it does not require any prior knowledge of the hypotheses or the detector performances, which are often unknown in real applications. Therefore, this proposed technique has the potential to improve the performances of the existing neonatal seizure detectors.</p> <p>In this thesis, we first review two newborn EEG models, one of which is used to generate neonatal EEG signals. The synthetic data is used later for testing purpose. We also review three existing algorithms and implement them to work as the local detectors. Then, we introduce the fusion algorithms applied in the fusion center for two different scenarios: large sample size and small sample size. We finally provide some numerical results to show the applicability, effectiveness, and the adaptability of the blind algorithms in the seizure detection problem. We also provide the testing results obtained using the synthetic to show the improvement of the detection system.</p> / Master of Applied Science (MASc)

<p>A novel linear programming approach for optimal contrast-tone mapping is proposed. A measure of contrast gain and a sister measure of tone distortion are defined for gray level transfer functions. These definitions allow us to depart from the current practice of histogram equalization and formulate contrast enhancement as a problem of maximizing contrast gain subject to a limit on tone distortion and possibly other constraints that suppress artifacts. The resulting contrast-tone optimization problem can be solved efficiently by linear programming. The proposed constrained optimization framework for contrast enhancement is general, and the user can add and fine tune the constraints to achieve desired visual effects. Experimental results are presented to illustrate the performance of the proposed method, demonstrating clearly superior performance of the new technique over histogram equalization. In addition, two locally adaptive contrast enhancement techniques by the proposed method are investigated.</p> / Master of Science (MS)

<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #464646} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #5a5a5a} span.s1 {color: #5a5a5a} span.s2 {color: #303030} span.s3 {color: #6a6a6a} span.s4 {color: #464646} span.s5 {color: #7b7b7b} span.s6 {color: #1a1a1a}</p> <p>Building a wireless sensor network (WSN) based on cognitive radio can be promising in the near future in order to provide data transmissions with quality of service requirements, while avoiding the interference in the license-free spectrum and high cost in accessing dedicated spectrum.</p> <p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #5a5a5a} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #464646} p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #6a6a6a} p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Times; color: #7b7b7b} span.s1 {font: 11.5px Times; color: #1a1a1a} span.s2 {color: #464646} span.s3 {color: #6a6a6a} span.s4 {color: #303030} span.s5 {color: #7b7b7b} span.s6 {color: #5a5a5a} span.s7 {color: #1a1a1a} span.s8 {color: #9b9b9b}</p> <p>In this thesis, we design a cognitive radio sensor network (CRSN) that integrates wireless sensor networking and cognitive radio technology, and analyze its performance. The network opportunistically accesses vacant channels in the licensed spectrum. \i\Then the current channel becomes unavailable, the devices switch to another available channel. The network supports both real-time and non-real-time traffic. Delay performance for the real-time traffic and throughput for the non-real- time traffic are studied. Two types of the real-time traffic are considered: bursty traffic where a burst of packets are generated periodically and each burst includes a random number of packets, and Poisson traffic where packet arrivals follow a Poisson process. Analytical models are developed for the average packet transmission delay 'when supporting each type of the real-time traffic, and simulation results of both the average transmission delay and packet drop rate performance are demonstrated . Our results indicate that real-time traffic can be effectively supported in the CRSN. Given the total number of candidate channels that can possibly be used by a CRSN, we consider how to allocate the channels among different clusters in order to maximize the system throughput. A heuristic scheme is designed to find the optimum channel allocations that achieves the same throughput as the exhaustive search method.</p> / Master of Applied Science (MASc)

<p> <p>Sensor nodes are often used in outdoor locations where they can be operated using solar power. When such a network is deployed, there are usually restrictions in the way that the nodes can be positioned, and this results in a node-dependent attenuation of the usable solar energy. This effect must be taken into account when placing the basestations used to communicate with the sensor nodes. In this thesis we consider the minimum-cost placement of data collecting basestation nodes so that outage-free operation of the sensor nodes is obtained. This is done by minimizing the number of basestations required when taking into account the energy costs of sensor node traffic relaying. An optimization is first formulated which gives a lower bound on the number of basestations that are required. Because of the complexity of the problem, two algorithms are proposed which can be used to do placements for practical problem sizes. These algorithms use the result from an iterated local search as a starting point, and then use an energy aware local optimization to obtain feasible basestation placements. Results are presented which show that the algorithms perform well for a variety of network scenarios.</p> </p> / Master of Applied Science (MASc)

<p>This thesis considers the design of secondary wireless mesh networks which use leased frequency channels. Considering the growing interest in using wireless services and the scarcity of frequency bands with proper propagation characteristics, reusing the currently licensed and underutilized bands is promising. A new initiative by the FCC, which allows the secondary usage of TV bands has encouraged both academia and industry to develop new devices and standards suitable for these operations.</p> <p>This thesis considers the design of secondary wireless mesh networks which use leased frequency channels. In a given geographic region the available channels are individually priced and leased exclusively. The usage of each channel is also subject to published interference constraints so that the primary user is not adversely affected. When the network is designed and deployed, the secondary user would like to minimize the costs of using the required resources while satisfying its own traffic and interference requirements. This problem is formulated as a mixed integer optimization which gives the optimum deployment cost as a function of the secondary node positioning, routing, and frequency allocations. Because of the problem's complexity, the optimum result can only be found for small problem sizes. To accommodate more practical deployments, four algorithms are proposed and their performance is compared to solutions obtained from the optimization.</p> / Master of Applied Science (MASc)

<p>Target classification has received significant attention in tracking literature. Algorithms for joint tracking and classification that are capable of improving tracking performance by exploiting the inter-dependency between target class and target kinematic behavior have already been proposed. However, in previous works the possible types of classes were assumed to be known a prior and the problem of class identification itself was not considered. In practice, the prior class information may not be always available. In this thesis, motivated by a people tracking problem, a joint class identification and target classification algorithm that can simultaneously build class types on the basis of target kinematic and feature measurements and classify targets according to the identified classes even when there is switching among classes is proposed. In addition, a new concept called "class quality" is introduced to improve the class identification and target classification accuracy. Accordingly, a modified performance evaluation metric for multiple object estimation, called Quality-based Optimal Subpattern Assignment (Q-OSPA), is proposed to quantify the class identification performance of the proposed algorithm. This metric provides more intuitively appealing results than the original OSPA metric when the quality of estimates is available. This new metric is also applicable in standard tracking problems where classification or class identification is not carried out, but a track quality measure is available as in the case of the Mnltiple Hypothesis Tracking (MHT) or the Joint Integrated Probabilistic Data Association (JIPDA) algorithm. Besides theoretical derivations, extensive simulations are presented to verify the effectiveness of the proposed algorithm.</p> / Master of Applied Science (MASc)

<p>A deformable object is a body that can undergo an alteration in shape and dimension as a result of external interactions. This characteristic makes deformable object handling considerably more difficult than handling rigid objects, which allow for the independent control of object grasping and manipulation. In the case of a deformable object, the grasping and manipulation interfere with one another, since a large enough force on the object may change its shape and location. One solution to this problem is the use of deformable object models. Models can provide an insight to the behavior of a deformable object subjected to various interactions with its environment. Lately, the use of deformable object models has received much attention from the industrial and medical communities.<br /><br />This thesis addresses the use of a deformable object model, developed using the mesh free Reproducing Kernel Particle Method RKPM, to aid in the accurate control of soft object manipulation path planning procedures and target stabilization during needle insertion procedures. Also, the deformable object is used as a part of an integrated system to control the manipulation of a physical object, using a robotic tool under position feedback from a stereoscopic camera.<br /><br />The results present a comparison between two different integration methods used to solve the deformable object model; The Gaussian Quadrature and a more efficient method referred to as the Collocated method, which is explained in Chapter 3. In both cases, the accuracy values of the results were comparable. A preliminary study was successfully completed using a coarse and refined object model to show a virtual concept of the physical system prior to its development. Using markers to dictate the performance of a physical object corresponding to the simulated object, experimental results were attained for a planar deformable object. Successful path following tasks were accomplished using the physical deformable object.<br /><br />Further, the target stabilization method proved to be successful in reducing the movement of a target with respect to the insertion direction of the needle in the tissue. The static paddle approach used the criteria of choosing the optimal paddle based on the highest reduction in target lateral movement, which showed to be case specific. The dynamic paddle approach was formulated to reposition the target back to its original position and was more robust to object characteristic changes.</p> / Master of Applied Science (MASc)