Electrical and Computer Engineering Commons^™

Using Bayesian Inference In Design Applications, Chung Yong Chan

Electronic Theses and Dissertations

This dissertation presents a new approach for solving engineering design problems such as the design of antenna arrays and finite impulse response (FIR) filters. In this approach, a design problem is cast as an inverse problem. The tools and methods previously developed for Bayesian inference are adapted and utilized to solve design problems. Given a desired design output, Bayesian parameter estimation and model comparison are employed to produce designs that meet the prescribed design specifications and requirements. In the Bayesian inference framework, the solution to a design problem is the posterior distribution, which is proportional to the product of the …

Optimization Of Inductively Coupled Plasma Dry Etching For Planar Waveguide Fabrication., Lim Weng Hong

Student Works (2010-2019)

Optimization of the Inductively Coupled Plasma (ICP) dry etching process parameters has been carried out. Seven main etching characteristics were considered in order to produce good etching quality. These characteristics are glass etching rates, selectivity of chromium to glass etching rate, channel side wall roughness, channel side wall vertical profile, channel cleanliness, critical dimension and resolution. Several ICP parameters that are affecting the etching characteristic were optimized in this work. These optimised ICP parameters obtained from this work are ICP power (880 W), bias power (45 W), operating chamber pressure (10 mtorr), reactant gas composition, reactant gas flow rate (35sccm …

Real-Time Model Predictive Control Of Quasi-Keyhole Pipe Welding, Kun Qian

University of Kentucky Doctoral Dissertations

Quasi-keyhole, including plasma keyhole and double-sided welding, is a novel approach proposed to operate the keyhole arc welding process. It can result in a high quality weld, but also raise higher demand of the operator. A computer control system to detect the keyhole and control the arc current can improve the performance of the welding process. To this effect, developing automatic pipe welding, instead of manual welding, is a hot research topic in the welding field.

The objective of this research is to design an automatic quasi-keyhole pipe welding system that can monitor the keyhole and control its establishment time …

Extraction And Prediction Of System Properties Using Variable-N-Gram Modeling And Compressive Hashing, Muthulakshmi Muthukumarasamy

University of Kentucky Doctoral Dissertations

In modern computer systems, memory accesses and power management are the two major performance limiting factors. Accesses to main memory are very slow when compared to operations within a processor chip. Hardware write buffers, caches, out-of-order execution, and prefetch logic, are commonly used to reduce the time spent waiting for main memory accesses. Compiler loop interchange and data layout transformations also can help. Unfortunately, large data structures often have access patterns for which none of the standard approaches are useful. Using smaller data structures can significantly improve performance by allowing the data to reside in higher levels of the memory …

Analysis And Optimization Of Electrical Systems In A Solar Car With Applications To Gato Del Sol Iii-Iv, Krishna Venkatesh Prayaga

University of Kentucky Master's Theses

Gato del Sol III, was powered by a solar array of 480 Silicon mono-crystalline photovoltaic cells. Maximum Power Point trackers efficiently made use of these cells and tracked the optimal load. The cells were mounted on a fiber glass and foam core composite shell. The shell rides on a lightweight aluminum space frame chassis, which is powered by a 95% efficient brushless DC motor. Gato del Sol IV was the University of Kentucky Solar Car Team’s (UKSCT) entry into the American Solar Car Challenge (ASC) 2010 event. The car makes use of 310 high density lithium-polymer batteries to account for …

Energy Reduction In Automotive Paint Shops A Review Of Hybrid/Electric Vehicle Battery Manufacturing, Claudia Patricia Arenas Guerrero

University of Kentucky Master's Theses

Automotive industry is facing fundamental challenges due to the rapid depletion of fossil fuels, energy saving and environmental concerns. The need of sustainable energy development has motivated the research of energy reduction and renewable energy sources. Efficient use of energy in vehicle manufacturing is demanded, as well as an alternative energy source to replace gasoline powered engines. In this thesis, we introduce a case study at an automotive paint shop, where the largest amount of energy consumption of an automotive assembly plant takes place. Additionally, we present a summary of recent advances in the area of hybrid and electrical vehicles …

Higate (High Grade Anti-Tamper Equipment) Prototype And Application To E-Discovery, Yui Sakurai, Yuki Ashino, Tetsutaro Uehara, Hiroshi Yoshiura, Ryoichi Sasaki

Journal of Digital Forensics, Security and Law

These days, most data is digitized and processed in various ways by computers. In the past, computer owners were free to process data as desired and to observe the inputted data as well as the interim results. However, the unrestricted processing of data and accessing of interim results even by computer users is associated with an increasing number of adverse events. These adverse events often occur when sensitive data such as personal or confidential business information must be handled by two or more parties, such as in the case of e-Discovery, used in legal proceedings, or epidemiologic studies. To solve …

Design And Evaluation Of An Audio-Frequency Transresistance Amplifier For Magnetic Tape Playback, Thomas R. Salvatierra

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Analog magnetic tape remains a medium of choice for high-fidelity sound recording and reproduction. Some of this fidelity is sacrificed during the tape playback process; an optimized playback preamplifier is therefore critical to the performance of the medium. Existing playback methods integrate the voltage generated across the reproduce head to obtain a signal directly proportional to the remanent magnetic flux of the tape. An alternate playback method proposes the use of a transresistance amplifier to convert flux-proportional reproduce head current directly to voltage. This eliminates the need for voltage integration and minimizes the amount of equalization performed upon playback. Circuit …

The Harmonic Distortion Reduction Of Phase-Angle Fired Scrs Feeding A Resistive Load Using Fuzzy Logic, Matthew A. Clark

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High power silicon controlled rectifiers (SCR) are used in the application of infrared radiation testing. A case study has been performed on a department of defense facility utilizing SCRs to transfer electrical energy to thermal energy. The facility is capable of generating up to 5000 °F across large cross-sectional areas, requiring tens of megawatts of power. The combination of high power, unbalanced loads, and SCR switching generate high harmonic disturbances that offer significant challenges for conventional linear control systems. In addition, unbalanced three-phase distribution systems are difficult to model, specifically during switching transients. Fuzzy logic is used to characterize the …

Development Of An Efficient Super-Resolution Image Reconstruction Algorithm For Implementation On A Hardware Platform, Pestak Thomas C.

Browse all Theses and Dissertations

There is a growing demand from numerous commercial and military applications for images with ever-improving spatial resolution. However, there are resolution-limiting factors inherent in all imaging systems. Decreasing pixel sizes and/or increasing sensor arrays are not always viable. Super-Resolution (SR) Image Reconstruction is an image processing technique that restores a high-resolution (HR) image from a series of low-resolution (LR) images of a particular scene. Recently, there has been extensive research on robust SR algorithms used for post-processing. The goal of this thesis is to explore the current SR research and design computationally efficient SR algorithms for real-time processing based on …

A Direction Finding System Using Log Periodic Dipole Antennas In A Sparsely Sampled Linear Array, Jonathan Andrew Weldon

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This thesis explores the use of wide band log periodic dipole array (LPDA) antennas in direction finding systems. A wide band log periodic antenna will be constructed and tested to ensure hardware capability. A novel approach utilizing non-uniform spacing in a linear array will be used to improve the spatial resolution of the direction finding system. These specialized linear arrays are known as minimum redundancy or non-redundant linear arrays.

A Structured Asic Approach To A Radiation Hardened By Design Digital Single Sideband Modulator For Digital Radio Frequency Memories, Thomas B. Pemberton

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Digital Radio Frequency Memories (DRFM) are widely used as modules in digital signal processing. These modules can provide several forms of signal manipulation and storage capabilities. With single event effects caused by environmental radiation the need for a radiation hardened DRFM is increased. Typical radiation hardening involves the use of specialized foundries utilizing proprietary CMOS libraries that are expensive to build or adding lead packages around a chip that is expensive and add weight to the chip. An alternative radiation hardening technique is to utilize a radiation hardened by design library. This library includes digital gates that have been hardened …

Frequency Domain Processing Based Chaos Communication For Cognitive Radio, Daniel Y. Sundersingh

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Chaotic systems are deterministic non-linear dynamical systems which have intrinsic properties such as: irregularity, aperiodicity, and are impossible to predict over long periods of time. Cognitive radio on the other hand, has emerged recently as a powerful means to tackle the spectrum congestion problem. The goal of this thesis is to combine the benefits of the chaos communication system with the cognitive radio to create a robust, highly secure, flexible chaotic cognitive radio system. We first begin with a short survey of chaotic communication and cognitive radio technology. Then we compare chaotic waveforms to other conventional PN sequences and show …

Wideband, High Data Rate Ku-Band Modulator Driver Amplifier For High Reliability Spaceborne Applications, Jeremy D. Gassmann

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The increased demand for high resolution satellite imagery for government, military, and commercial applications is driving the need for high data rate, millimeter-wave transmission systems to relay imagery information to a ground-based end user. An important aspect of this system which interfaces digital information to the RF domain is the modulator driver. The current trend in miniaturization of electronics leaves systems more vulnerable to single-event radiation effects in spaceborne applications. In an effort to overcome this deficiency, a wideband, high data rate modulator driver circuit has been designed, built, and tested using only high reliability space rated electronic components. To …

An Automated Approach To A 90-Nm Cmos Drfm Dssm Circuit Design, Thomas A. Hopkins

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A digital single sideband modulator (DSSM) for a digital radio frequency memory (DRFM) was designed and implemented in a commercial 90-nm radiation-hardened-by-design (RHBD) structured ASIC by Thomas Pemberton in cite{Pemberton}. This thesis synthesized the same DSSM structure in a non-hardened 90-nm commercial process and compared the synthesis results of the two for power, delay, and area. The number of I/O bits and taps in cite{Pemberton} and this thesis were purposely made high to create a large target for radiation testing. As should be expected, the RHBD DSSM reported greater power and area. However, the RHBD power models were only estimates. …

Adaptive Thresholding For Detection Of Radar Receiver Signals, Stephen R. Benson

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Digital microwave receivers play a critical role in many of today's modern radar tracking systems. The need for these digital receivers to push the boundaries in terms of bandwidth and input dynamic ranges (DR) is vital for their use in radar signal tracking. Significant research has been conducted in the area of the fast Fourier transform (FFT) to aid in continuing to enhance the performance capabilities of digital microwave receivers. However, with the advancement and increased complexity of these systems, the need for an efficient and effective adaptive thresholding technique is becoming ever more present.

The proposed adaptive thresholding technique …

Hyperspectral Methods Of Determining Grit Application Density On Sandpaper, Lee A. Clark

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A low cost real time method of determining the density of grit applied to sandpaper does not currently exist. This thesis will explore three methods for determining grit density from digital image data. A means to characterize the application in terms of frequency by using direct cosine transform basis images will be explored. An RX detector algorithm to characterize the image background will be tested. A linear unmixing methodology will be developed that characterizes the proportion of glue and grit present in each hyperspectral pixel vector.

Sulfur-Tolerant Catalyst For The Solid Oxide Fuel Cell, Bozeman Joe Frank Iii

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JP-8 fuel is easily accessible, transportable, and has hydrogen content essential to solid oxide fuel cell (SOFC) operation. However, this syngas has sulfur content which results in a poisonous hydrogen sulfide that degrades electrochemical activity and causes complete SOFC failure in some cases. The goal is to synthesize and verify a cost-effective, catalyst supported on cerium oxide that either stabilizes ionic conductivity in the presence of hydrogen sulfide and/or is highly sulfur-resistant. After thorough computational analysis, it was concluded that the platinum-copper skin catalyst was the most cost-effective, sulfur-resistant catalyst. Experimental synthesis of copper, platinum, and platinum-copper skin catalysts supported …

Measurement And Modeling Of Infrared Nonlinear Absorption Coefficients And Laser-Induced Damage Thresholds In Ge And Gasb, T. J. Wagner, M. A. Bohn, Ronald A. Coutu Jr., L. P. Gonzalez, J. M. Murray, K. L. Schepler, S. Guha

Electrical and Computer Engineering Faculty Research and Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond …

Fault Diagnosis Of Vehicular Electric Power Generation And Storage, Hithesh Sanjiva Uliyar

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Automotive vehicles are becoming increasingly dependent on electric power, and this trend will accelerate. The health of the vehicular electric power generation and storage (EPGS) system is crucial to enhance vehicle safety, fuel economy, and customer satisfaction.

In this research, a state-of-health (SOH) monitoring method is developed for automotive EPGS system, focusing on alternator related faults. Parity relations, characterizing the correlation among EPGS system signals under normal operating conditions, are generated using principal/minor component analysis techniques. Based on a design of structured residuals, the faults under consideration, including shorted diodes, belt slippage, and regulator fault, are successfully detected and isolated. …