Master of Science / Department of Electrical and Computer Engineering / Stephen A. Dyer / Every person with an electronics background will be familiar with the three fundamental circuit elements—the resistor, the capacitor, and the inductor.These three elements are defined by the relation between two of the four fundamental circuit variables—current, voltage, charge and flux.In 1971, Leon Chua reasoned on the grounds of symmetry that there should be a fourth fundamental circuit element which gives the relationship between flux and charge.He named this circuit element the memristor, which is short for―"memory resistor."In May 2008, researchers at HP Labs published a paper announcing a model for the physical realization of the memristor. This report focuses on the memristor and reviews its properties.The HP model for the memristor is also discussed, and its behavior is studied through simulations.A few of the potential applications of the memristor are presented.

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / A frequency synthesizer is a control system which employs a reference signal from a component, such as a crystal oscillator, with excellent phase and frequency stability to synthesize higher frequencies with similarly desirable characteristics. Such a control system is at the heart of many communication schemes. Due to the digital circuitry used in frequency synthesis, it is relatively straightforward to synthesize frequencies at integer multiples of the reference signal frequency. A synthesizer which achieves this is called an integer-N frequency synthesizer. The main challenge in the design of integer-N synthesizers is to reduce phase noise introduced by circuitry while achieving a needed frequency resolution. Noise can be spectrally spread by conversions in the loop which are non-linear, so the strategy to reduce noise is two-fold. Control-loop and circuit design techniques can be used to reduce device noise, but it is also important to make sure that the noise performance is not degraded by spectral spreading within the loop. This thesis addresses primarily the latter approach with the design and implementation of circuits targeting a specific conversion within the loop. Frequency resolution of a synthesizer can be improved by introducing additional circuitry and complexity. This additional complexity makes it possible to multiply the reference frequency by a fractional number and thus achieve higher frequency resolution. A control system which achieves this is called a fractional-N frequency synthesizer. The cost associated with the increased frequency resolution is a form of noise that is deterministic called spurious noise. This spurious noise can also be spread and amplified by non-linear conversions in the control loop. A quantitative understanding of the magnitude of this noise that is not readily available in the literature was developed in this research. A comparison between several implementations of integrated frequency synthesis was also carried out in this research with the intent of providing guidelines to produce a better performing synthesizer. These implementations differ in key components of the loop where linearity is of particular importance.

Master of Science / Department of Electrical and Computer Engineering / D. V. Satish Chandra / The future of healthcare delivery systems and telemedical applications will undergo a radical change due to the developments in wearable technologies, medical sensors, mobile computing and communication techniques. E-health was born with the integration of networks and telecommunications when dealing with applications of collecting, sorting and transferring medical data from distant locations for performing remote medical collaborations and diagnosis. Healthcare systems in recent years rely on images acquired in two dimensional (2D) domain in the case of still images, or three dimensional (3D) domain for volumetric images or video sequences. Images are acquired with many modalities including X-ray, positron emission tomography (PET), magnetic resonance imaging (MRI), computed axial tomography (CAT) and ultrasound. Medical information is either in multidimensional or multi resolution form, this creates enormous amount of data. Efficient storage, retrieval, management and transmission of this voluminous data is extremely complex. One of the solutions to reduce this complex problem is to compress the medical data losslessly so that the diagnostics capabilities are not compromised. This report proposes techniques that combine integer transforms and predictive coding to enhance the performance of lossless compression. The performance of the proposed techniques is evaluated using compression measures such as entropy and scaled entropy.

Master of Science / Department of Electrical and Computer Engineering / Don M. Gruenbacher / This thesis presents a novel device for delaying Ethernet traffic in a lab setting. Ethernet is the leading standard for communications between computing devices. With the advent of streaming media such as voice over IP phone service and real-time control systems over Ethernet, applications are being rapidly developed that must meet strict communication reliability and timing constraints. Increasingly, these systems must be examined in real world scenarios before actual hardware deployment or protocol release. This increases the demand for both testing equipment and well trained network engineers. Commercial Ethernet delay testing devices are expensive, hardware specific, and not flexible enough for educational purposes. These short-comings make it necessary to design a robust Field Programmable Gate Array (FPGA) based Ethernet delay device that is up to the rigor of educational and research settings. Our approach is based on the inexpensive, high performance Altera Stratix II GX PCI Express development board which can easily be adapted for different delay scenarios. The system's FPGA hardware was developed in Verilog, an industry standard hardware description language, so users will be able to quickly learn, adapt and operate the system. Software for the system's soft processor was developed in C. The device provides a wide range of packet delay from nearly zero up to over fifty milliseconds, as well as providing an easy to use interface with on-the-fly variable delay adjustment. Theoretical throughput was up to 1Gb/s; skew and jitter measurements were comparable with common network switches. These properties allow the device to provide an easy-to-use, inexpensive method to delay Ethernet traffic in lab settings and the device also creates a starting point for future students and researchers to develop high speed traffic delay testbeds. Future work will include 10Gb/s throughput, additional memory capacity and additional software implemented delay profiles.

Master of Science / Department of Electrical and Computer Engineering / D. V. Satish Chandra / The area of health care delivery and medical data management has undergone a huge transformation in the recent years. This is directly related to the significant advancements in information and communication technologies. Vast amounts of medical data is to be efficiently stored, retrieved and distributed. The above mentioned reasons collectively have created new challenges, especially regarding the security of this highly sensitive information. Digital watermarking is a recently established area of research with many applications. The potential of medical image watermarking has only recently been realized by the research community. Medical image watermarking can be exploited to simultaneously address the issues of data security, archiving, retrieval and most importantly data authentication. This report discusses the perspectives of digital watermarking in the area of medical data management. Integer wavelet transform has been used to achieve reversible watermarking as every detail is important, especially in the case of medical images. Multiple watermarks which convey patient’s personal and examination data, keywords for information retrieval and the physician’s digital signature for authentication are embedded in an imperceptible manner. Different types of medical images have been acquired and tested using the proposed method.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Wireless broadband communications is a rapidly growing industry. New enabling technologies such as multi-carrier code division multiple access (MC-CDMA) are shaping the future of wireless systems. However, research efforts in improving MC-CDMA receiver performance have received limited attention and there is a need for innovative receiver designs for next generation MC-CDMA. In this thesis, we propose novel multi-user detection (MUD) schemes to enhance the performance of both synchronous and asynchronous MC-CDMA. First, we adapt the ant colony optimization (ACO) approach to solve the optimal MUD problem in MC-CDMA systems. Our simulations indicate that the ACO based MUD converges to the optimal BER performance in relatively few iterations providing more that 95% savings in computational complexity. Second, we propose a new MUD structure specifically for asynchronous MC-CDMA. Previously proposed MUDs for asynchronous MC-CDMA perform the detection for one user (desired user) at a time, mandating multiple runs of the algorithm to detect all users' symbols. In this thesis, for the first time we present a MUD structure that detects all users' symbols simultaneously in one run by extending the receiver's integration window to capture the energy scattered in two consecutive symbol durations. We derive the optimal, decorrelator and minimum mean square error (MMSE) MUD for the extended window case. Our simulations demonstrate that the proposed MUD structures not only perform similar to a MUD that detects one user at a time, but its computational complexity is significantly lower. Finally, we extend the MUD ideas to multicarrier implementation of single carrier systems. Specifically, we employ the novel MUD structure as a multi-symbol detection scheme in CI-CDMA and illustrate the resulting performance gain via simulations.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Anil Pahwa / This dissertation introduces a novel approach for optimally operating a day-ahead electricity market not only by economically dispatching the generation resources but also by minimizing the influences of market manipulation attempts by the individual generator-owning companies while ensuring that the power system constraints are not violated. Since economic operation of the market conflicts with the individual profit maximization tactics such as market manipulation by generator-owning companies, a methodology that is capable of simultaneously optimizing these two competing objectives has to be selected. Although numerous previous studies have been undertaken on the economic operation of day-ahead markets and other independent studies have been conducted on the mitigation of market power, the operation of a day-ahead electricity market considering these two conflicting objectives simultaneously has not been undertaken previously. These facts provided the incentive and the novelty for this study. A literature survey revealed that many of the traditional solution algorithms convert multi-objective functions into either a single-objective function using weighting schemas or undertake optimization of one function at a time. Hence, these approaches do not truly optimize the multi-objectives concurrently. Due to these inherent deficiencies of the traditional algorithms, the use of alternative non-traditional solution algorithms for such problems has become popular and widely used. Of these, multi-objective evolutionary algorithms (MOEA) have received wide acceptance due to their solution quality and robustness. In the present research, three distinct algorithms were considered: a non-dominated sorting genetic algorithm II (NSGA II), a multi-objective tabu search algorithm (MOTS) and a hybrid of multi-objective tabu search and genetic algorithm (MOTS/GA). The accuracy and quality of the results from these algorithms for applications similar to the problem investigated here reinforced the selection of these algorithms. The results obtained from each of the three algorithms used in the evaluations are very comparable. Thus one could safely conclude that the results obtained are valid. Three distinct test power systems operating under different conditions were studied for evaluating the suitability of each of these algorithms. The test cases included scenarios in which the power system was unconstrained as well as constrained. Repeated simulations carried out for the same test case with varying starting points provided evidence that the algorithms and the solutions were robust. Influences of different market concentrations on the optimal economic dispatch are evidenced by the pareto-optimal-fronts obtained for each test case studied. Results obtained from a traditional linear programming (LP) based solution algorithm that is used at present by many market operators are also presented for comparison. Very high market-concentration-indices were found for each solution from the LP algorithm. This suggests the need to use a formal method for mitigating market concentration. Operating the market at industry-recommended threshold levels of market concentration for selecting an optimal operational point is presented for all test cases studied. Given that a solution-set instead of a single operating point is found from the multi-objective optimization methods, additional flexibility to select any operational point based on the preference of those operating the market clearly is an added benefit of using multi-objective optimization methods. However, in order to help the market operator, a more logical fuzzy decision criterion was tested for selecting a suitable operating point. The results show that the optimal operating point chosen using the fuzzy decision criterion provides a higher economic benefit to the market, although at a slightly increased market concentration. Since the main objective of this research was to simultaneously optimize the economic operation of a day-ahead market while ensuring minimal market power by individual generator owners, the proposed method is much improved from the current industry practice. The current practice of after-the-fact mitigation of market power has created various problems for both the market operator and the market participants, giving rise to a large numbers of disputes and resettlement activities. Hence, an approach that mitigates market power at the time of market dispatch as used in this research would bring about a more efficient market operation.

Master of Science / Department of Electrical and Computer Engineering / Andrew Rys / Since its discovery in the 1940's, barium titanate has become one of the more popular dielectric materials for use in discrete capacitors due to its high relative permittivity. Recently, consumer electronics have decreased in size, driving the need for smaller electronic components. To fill this need, researchers have created polycrystalline barium titanate with individual grains in the nanometer scale. With this decrease in size, many problems arise. This paper will outline the effects on the dielectric properties due to shrinking the individual grains, as well as discuss techniques for dielectric measurement of this material.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / Due to the underutilization of scarce radio spectrum resources, there is a major shift from an exclusive use model to a spectrum sharing model. This model has been successful in unlicensed bands where wireless standards such as Bluetooth and WLAN IEEE802.11 have flourished. In order to extend this model to licensed bands, a smart radio is required. The cognitive radio is a smart radio that leverages its knowledge of the local environment in order to operate with acceptable interference to primary users in the band. The brain of the cognitive radio is encapsulated in the sensing receiver. Using the sensing receiver, the cognitive radio observes the activity in a band and adapts its communication link parameters so that the interference is minimal. The sensing receiver attributes include wideband operation and agility. The receiver must be able to make fast decisions accurately of the spectrum activities. To date, a practical sensing receiver has been a major stumbling block in the realization of cognitive radio. In our research, we demonstrate that a practical sensing receiver is in fact feasible. Our research objectives are: (1) to develop a sensing receiver based on current technology, and (2) to augment our solution with an associated algorithm that makes fast and accurate sensing possible. Our proposed solution is a Dedicated Sensing Receiver (DSR) that employs an adaptive algorithm to enable the cognitive radio to effectively operate in a competitive environment. The DSR algorithm divides the frequency band into coarse sensing bins which are further divided into fine sensing bins. We derive a mathematical model that is optimized for minimizing sensing time. The optimization algorithm generates the optimum number of coarse and fine sensing bins based on environment conditions and the radio implementation. Our results illustrate the DSR’s ability to reduce open spectrum recognition time by over 10X while operating over a broad range of frequencies. This drastic improvement opens the door for the cognitive radio technology to be used in commercial applications in the near future and more importantly, it allows for the cognitive radio to succeed in time sensitive applications such as voice or video. We have also developed an end to end simulation platform to model the algorithm and the dedicated sensing receiver performance.

Master of Science / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / In this thesis, we investigate two carrier tracking loops. We provide a basic overview of phase-lock loops. We derive a two-state EKF tracking loop. The two-state EKF estimates phase error and frequency error. The estimate of frequency error is fed back to an NCO to complete the tracking loop.