Engineering Commons^™

Highly Efficient Maximum Power Point Tracking Using A Quasi-Double-Boost Dc/Dc Converter For Photovoltaic Systems, Christopher J. Lohmeier

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Solar photovoltaic (PV) panels are a great source of renewable energy generation. The biggest problem with solar systems is relatively low efficiency and high cost. This work hopes to alleviate this problem by using novel power electronic converter and control designs. An electronic DC/DC converter, called “Quasi-Double-Boost DC/DC Converter,” is designed for a Solar PV system. A Maximum Power Point Tracking (MTTP) algorithm is implemented through this converter. This algorithm allows the PV system to work at its highest efficiency. Different current sensing and sensorless technologies used with the converter for the MPPT algorithm are offered and tested. Design aspects …

An Rf Cmos Implementation Of An Adaptive Filter For Narrow-Band Interferer Suppression In Uwb Systems, Markus Both

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Ultra-wideband (UWB) technology is a new type of technology for wireless communication that is based on the transmission of low power sub-nanosecond pulses. UWB communication utilizes a large bandwidth that overlaps and is coexistent with other wireless communication standards that can be also considered as narrow-band interferers. Because UWB systems are highly susceptible to narrow-band interferers, there is a demand for interferer suppression. An adaptive filter consisting of a two-element diversity receiver that performs minimum mean square error combining (MMSE) by the LMS algorithm is proposed. Thereby the elements of the LMS algorithm as well as the receiver LNA were …

Detection-Assisted Object Tracking By Mobile Cameras, Li He

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Tracking-by-detection is a class of new tracking approaches that utilizes recent development of object detection algorithms. This type of approach performs object detection for each frame and uses data association algorithms to associate new observations to existing targets. Inspired by the core idea of the tracking-by-detection framework, we propose a new framework called detection-assisted tracking where object detection algorithm provides help to the tracking algorithm when such help is necessary; thus object detection, a very time consuming task, is performed only when needed. The proposed framework is also able to handle complicated scenarios where cameras are allowed to move, and …

Optical And Magnetic Properties Of Feni Slanted Columnar Thin Films Infiltrated With Pmma And Fe3O4 Nanoparticles, Dan Liang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, dielectric polymer and magnetic nanoparticles were utilized to hybridize FeNi Slanted columnar thin films (SCTFs). Firstly Fe₃O₄ in PMMA matrix was prepared by physical blending process. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to investigate the dispersion of the nanoparticles in PMMA matrix and the preparation conditions were varied to optimize the dispersion. The hybridized materials were prepared by the infiltration of PMMA and 5 wt% Fe₃O₄ nanoparticles/PMMA to the voids of FeNi SCTFs. Spin-coating and annealing process were employed to reach an excellent infiltration.

The structural …

A 2-D Processor Array For Massively Parallel Image Processing, Anantha Krishna Nelliparthi

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The concept of introducing image processing logic within the spatial gaps of an array of photodiodes is the key factor behind the presented work. A two-dimensional massively parallel image processing paradigm based on 8X8 pixel neighborhood digital processors has been designed. A low complexity processor array architecture along with its instruction set has been designed and fully verified on a FPGA platform. Various image processing tests have been run on the FPGA platform to demonstrate the functionality of a design that uses 12 parallel processors. The test results indicate that the architecture is scalable to support high frame rates while …

In-Situ Ellipsometry Characterization Of Anodically Grown Silicon Dioxide And Lithium Intercalation Into Silicon, Eric A. Montgomery

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, in-situ ellipsometry and electroanalytical investigations of two electrochemical processes are reported: including the formation of anodically grown silicon dioxide and the intercalation of lithium into silicon. Analysis of the ellipsometry data shows that the anodically grown silicon dioxide layer is uniform and has similar properties as thermally grown silicon dioxide. The lithium-ion intercalation data reveals non-uniform thin film formation, which requires further studies and development of appropriate ellipsometric optical models.

Advisers: Eva Schubert and Mathias Schubert

Power Control And Security Games For Wireless Communication Networks, Bo Liang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, game theoretic analysis of wireless communication networks has been performed. Game theory provides valuable tools can be used to solve problem of conflict and cooperation in wireless communication networks. Game theoretic tools can be applied to multiple layers of wireless networks. First, we consider power control issues at the physical layer of wireless networks. A game theoretic analysis for resource allocation policies in fading interference channels in the presence of quality of service (QoS) constraints is performed. We model a two player non-cooperative power control game and assume that both transmitters and receivers know the channel side …

Simulation And Fabrication Of 3d Spiral Photonic Crystals As Circular Polarizers, Xuejian Li

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Three-dimensional (3D) spiral photonic crystals (PhCs) have a periodic varied refractive index (RI) with the periodicity comparable to the wavelength of incident light. They can pass circularly polarized (CP) light with handedness opposite to their own structures’ handedness while block the polarization state with the same handedness. Three-dimensional spiral PhCs for use as circular polarizers have two main advantages over conventional circular polarizers. On the one hand, it has wide operation wavelength based on the photonic band gap caused by PhCs and the interaction between CP light and each individual spiral structure. On the other hand, the height of each …

Isotope Identification And Source Directional Determination Using Gamma Radiation Profiling, Christopher L. Schrage

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This thesis presents a method for evaluating gamma radiation profiles using a low power gamma radiation detector system (GRDS). This method enables multiple radioactive gamma isotopes to be identified and determine the respective vector directions of those sources relative to the GRDS location. This detection method must be accurate, implemented as a handheld or fixed solution, and have a suitable battery life for a variety of industrial needs.

This paper will first explain the low power GRDS that was used for developing these detection methods. The target gamma isotopes that are used for validating these methods will be described along …

Low Complexity Feature Extraction For Classification Of Harmonic Signals, Peter William

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this dissertation, feature extraction algorithms have been developed for extraction of characteristic features from harmonic signals. The common theme for all developed algorithms is the simplicity in generating a significant set of features directly from the time domain harmonic signal. The features are a time domain representation of the composite, yet sparse, harmonic signature in the spectral domain.The algorithms are adequate for low-power unattended sensors which perform sensing, feature extraction, and classification in a stand-alone scenario. The first algorithm generates the characteristic features using only the duration between successive zero-crossing intervals. The second algorithm estimates the harmonics’ amplitudes of …

Cooperative Wireless Communications: The Impact Of Channel Uncertainty And Physical-Layer Security Considerations, Junwei Zhang

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, cooperative wireless communication strategies are studied in the presence of channel uncertainty and physical-layer security considerations. Initially, achievable rates and resource allocation strategies for imperfectly-known fading relay channels are investigated. Amplify-and-forward (AF) and decode-and-forward (DF) relaying schemes with different degrees of cooperation are considered. The corresponding achievable rate expressions are obtained and efficient resource allocation strategies are identified. Then, the analysis is extended to two-way decode-and-forward (DF) fading relay channels. In the second part of the thesis, the concentration is on wireless information-theoretic security. First, collaborative beamforming schemes for both DF and AF relaying are studied under …

Cyclostationary Detection For Ofdm In Cognitive Radio Systems, Marcos E. Castro

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Research on cognitive radio systems has attracted much interest in the last 10 years. Cognitive radio is born as a paradigm and since then the idea has seen contribution from technical disciplines under different conceptual layers. Since then improvements on processing capabilities have supported the current achievements and even made possible to move some of them from the research arena to markets.

Cognitive radio implies a revolution that is even asking for changes in current business models, changes at the infrastructure levels, changes in legislation and requiring state of the art technology.

Spectrum sensing is maybe the most important part …

Wireless Embedded Smart Cameras: Performance Analysis And Their Application To Fall Detection For Eldercare., Alvaro Pinto

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Wireless Embedded Smart Camera Networks has received a lot of attention from academia and industry because they are small in size and easy to deploy, and they offer a multitude of attractive applications. They can be used for embedded single unit applications, or can be networked for multi-camera applications.

We first analyze three different operation scenarios for a wireless vision sensor network wherein different levels of local processing is performed. A detailed quantitative comparison of three operation scenarios are presented in terms of energy consumption and latency. This quantitative analysis provides the motivation for performing high-level local processing and decision …

Wireless Communications And Cognitive Radio Transmissions Under Quality Of Service Constraints And Channel Uncertainty, Sami Akin

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, we study wireless communications and cognitive radio transmissions under quality of service (QoS) constraints and channel uncertainty. Initially, we focus on a time-varying Rayleigh fading channel and assume that no prior channel knowledge is available at the transmitter and the receiver. We investigate the performance of pilot-assisted wireless transmission strategies. In particular, we analyze different channel estimation techniques, including single-pilot minimum mean-square-error (MMSE) estimation, and causal and noncausal Wiener filters, and analyze efficient resource allocation strategies. Subsequently, we study the training-based transmission and reception schemes over a priori unknown, Rayleigh fading relay channels in which the fading …

Computational Genomic Signatures And Metagenomics, Ozkan U. Nalbantoglu

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Mathematical characterizations of biological sequences form one of the main elements of bioinformatics. In this work, a class of DNA sequence characterization, namely computational genomics signatures, which capture global features of these sequences is used to address emerging computational biology challenges. Because of the species specificity and pervasiveness of genome signatures, it is possible to use these signatures to characterize and identify a genome or a taxonomic unit using a short genome fragment from that source. However, the identification accuracy is generally poor when the sequence model and the sequence distance measure are not selected carefully. We show that the …