Electrical and Computer Engineering Commons^™

Passive Attitude Stabilization For Small Satellites, Samir Ahmed Rawashdeh

University of Kentucky Master's Theses

This thesis addresses the problem of designing and evaluating passive satellite attitude control systems for small satellites. Passive stabilization techniques such as Gravity Gradient stabilization, Passive Magnetic Stabilization, and Aerodynamic stabilization in Low Earth Orbit utilize the geometric and magnetic design of a satellite and the orbit properties to passively provide attitude stabilization and basic pointing. The design of such stabilization systems can be done using a high fidelity simulation of the satellite and the environmental effects in the orbit under consideration to study the on-orbit behavior and the effectiveness of the stability system in overcoming the disturbance torques. The …

Leakage Current Reduction Of Mos Capacitor Induced By Rapid Thermal Processing, Yichun Wang

University of Kentucky Master's Theses

With the MOSFET scaling practice, the performance of IC devices is improved tremendously as we experienced in the last decades. However, the small semiconductor devices also bring some drawbacks among which the high gate leakage current is becoming increasingly serious.

This thesis work is focused on the of gate leakage current reduction in thin oxide semiconductor devices. The method being studied is the Phonon Energy Coupling Enhancement (PECE) effect induced by Rapid Thermal Processing (RTP). The basic MOS capacitors are used to check improvements of leakage current reduction after appropriate RTP process.

Through sets of experiments, it is found that …

Spheroid Detection In 2d Images Using Circular Hough Transform, Priyanka Chaudhary

University of Kentucky Master's Theses

Three-dimensional endothelial cell sprouting assay (3D-ECSA) exhibits differentiation of endothelial cells into sprouting structures inside a 3D matrix of collagen I. It is a screening tool to study endothelial cell behavior and identification of angiogenesis inhibitors. The shape and size of an EC spheroid (aggregation of ~ 750 cells) is important with respect to its growth performance in presence of angiogenic stimulators. Apparently, tubules formed on malformed spheroids lack homogeneity in terms of density and length. This requires segregation of well formed spheroids from malformed ones to obtain better performance metrics. We aim to develop and validate an automated imaging …

Fpga Based Parallel Implementation Of Stacked Error Diffusion Algorithm, Rishvanth Kora Venugopal

University of Kentucky Master's Theses

Digital halftoning is a crucial technique used in digital printers to convert a continuoustone image into a pattern of black and white dots. Halftoning is used since printers have a limited availability of inks and cannot reproduce all the color intensities in a continuous image. Error Diffusion is an algorithm in halftoning that iteratively quantizes pixels in a neighborhood dependent fashion. This thesis focuses on the development and design of a parallel scalable hardware architecture for high performance implementation of a high quality Stacked Error Diffusion algorithm. The algorithm is described in ‘C’ and requires a significant processing time when …

Statistical Models For Constant False-Alarm Rate Threshold Estimation In Sound Source Detection Systems, Sayed Mahdi Saghaian Nejad Esfahani

University of Kentucky Master's Theses

Constant False Alarm Rate (CFAR) Processors are important for applications where thousands of detection tests are made per second, such as in radar. This thesis introduces a new method for CFAR threshold estimation that is particularly applicable to sound source detection with distributed microphone systems. The novel CFAR Processor exploits the near symmetry about 0 for the acoustic pixel values created by steered-response coherent power in conjunction with a partial whitening preprocessor to estimate thresholds for positive values, which represent potential targets.

To remove the low frequency components responsible for degrading CFAR performance, fixed and adaptive high-pass filters are applied. …

Design And Implementation Of The Instruction Set Architecture For Data Lars, Kalyan Ponnala

University of Kentucky Master's Theses

The ideal memory system assumed by most programmers is one which has high capacity, yet allows any word to be accessed instantaneously. To make the hardware approximate this performance, an increasingly complex memory hierarchy, using caches and techniques like automatic prefetch, has evolved. However, as the gap between processor and memory speeds continues to widen, these programmer-visible mechanisms are becoming inadequate.

Part of the recent increase in processor performance has been due to the introduction of programmer/compiler-visible SWAR (SIMD Within A Register) parallel processing on increasingly wide DATA LARs (Line Associative Registers) as a way to both improve data access …

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 …

Performance Analysis Of Srcp Image Based Sound Source Detection Algorithms, Praveen Reddy Nalavolu

University of Kentucky Master's Theses

Steered Response Power based algorithms are widely used for finding sound source location using microphone array systems. SRCP-PHAT is one such algorithm that has a robust performance under noisy and reverberant conditions. The algorithm creates a likelihood function over the field of view. This thesis employs image processing methods on SRCP-PHAT images, to exploit the difference in power levels and pixel patterns to discriminate between sound source and background pixels. Hough Transform based ellipse detection is used to identify the sound source locations by finding the centers of elliptical edge pixel regions typical of source patterns. Monte Carlo simulations of …

Theoretical Modeling And Analysis Of Ammonia Gas Sensing Properties Of Vertically Aligned Multiwalled Carbon Nanotube Resistive Sensors And Enhancing Their Sensitivity, Shripriya Darshini Poduri

University of Kentucky Master's Theses

Vertically aligned Multiwalled Carbon Nanotubes (MWCNTs) were grown in the pores of Anodized Aluminum Oxide (AAO) templates and investigated for resistive sensor applications. High Sensitivity of 23% to low concentration (100 ppm) of ammonia was observed. An equivalent circuit model was developed to understand the current flow path in the resistive sensor. This helped us in achieving high sensitivities through amorphous carbon (a-C) layer thickness tailoring by employing post-growth processing techniques like plasma etching.

A simulation model in MATLAB was developed to calculate the device resistance and the change in the sensitivity as a function of device parameters. The steady …

Testing Program For Kysat‐1, Jason Robert Bratcher

University of Kentucky Master's Theses

Years of success in the aerospace industry has taught Kentucky Space several lessons. This thesis will summarize the accomplishments in an attempt to formulate a well-defined program for designing and testing small spacecraft in an environment with strict financial restraints. The motivation for producing this well-defined platform for testing small spacecraft arose when Kentucky Space became the liaison between NASA and its customers for the NanoRacks and CubeLab module program. Having a solid program for testing small spacecraft will allow future student programs to easily set standards for experiment payloads. Also by discussing obstacles for smaller programs such as restraints …

Verilog Design And Fpga Prototype Of A Nanocontroller System, Akshay Vummannagari

University of Kentucky Master's Theses

Many new fabrication technologies, from nanotechnology and MEMS to printed organic semiconductors, center on constructing arrays of large numbers of sensors, actuators, or other devices on a single substrate. The utility of such an array could be greatly enhanced if each device could be managed by a programmable controller and all of these controllers could coordinate their actions as a massively-parallel computer. Kentucky Architecture nanocontroller array with very low per controller circuit complexity can provide efficient control of nanotechnology devices.

This thesis provides a detailed description of the control hierarchy of a digital system needed to build "nanocontrollers" suitable for …

Gold Nanospheres And Gold Nanorods As Localized Surface Plasmon Resonance Sensors, Akil Mannan Matcheswala

University of Kentucky Master's Theses

A novel localized surface plasmon resonance (LSPR) sensor that differentiates between background refractive index changes and surface-binding of a target analyte (e.g. a target molecule, protein, or bacterium) is presented. Standard, single channel LSPR sensors cannot differentiate these two effects as their design allows only one mode to be coupled. This novel technique uses two surface plasmon modes to simultaneously measure surface binding and solution refractive index changes. This increases the sensitivity of the sensor.

Different channels or modes can be created in sensors with the introduction of gold nanospheres or gold nanorods that act as receptor mechanisms. Once immobilization …

Issues Related To The Numerical Implementation Of A Sparse Method For The Solution Of Volume Integral Equations At Low Frequencies, Kiran Arcot

University of Kentucky Master's Theses

Computational electromagnetic modeling involves generating system matrices by discretizing integral equations and solving the resulting system of linear equations. Many methods of solving the system of linear equations exist and one such method is the factorization of the matrix using the so called local-global solution (LOGOS) modes. Computer codes to perform the discretization of the integral equations, filling of the matrix, and the subsequent LOGOS factorization have previously been developed by others. However, these codes are limited to complex double precision arithmetic only.

This thesis extends and expands the existing computer by creating a more general implementation that is able …

A Novel Message Routing Layer For The Communication Management Of Distributed Embedded Systems, Darren Jacob Brown

University of Kentucky Master's Theses

Fault tolerant and distributed embedded systems are research areas that have the interest of such entities as NASA, the Department of Defense, and various other government agencies, corporations, and universities. Taking a system and designing it to work in the presence of faults is appealing to these entities as it inherently increases the reliability of the deployed system. There are a few different fault tolerant techniques that can be implemented in a system design to handle faults as they occur. One such technique is the reconfiguration of a portion of the system to a redundant resource. This is a difficult …

Audio Scene Segementation Using A Microphone Array And Auditory Features, Harikrishnan Unnikrishnan

University of Kentucky Master's Theses

Auditory stream denotes the abstract effect a source creates in the mind of the listener. An auditory scene consists of many streams, which the listener uses to analyze and understand the environment. Computer analyses that attempt to mimic human analysis of a scene must first perform Audio Scene Segmentation (ASS). ASS find applications in surveillance, automatic speech recognition and human computer interfaces. Microphone arrays can be employed for extracting streams corresponding to spatially separated sources. However, when a source moves to a new location during a period of silence, such a system loses track of the source. This results in …

Accelerated Aging Of Mwcnt Filled Electrically Conductive Adhesives, Ashwanth Reddy Vangala

University of Kentucky Master's Theses

Electrically conductive adhesives (ECA) are discussed and studied with everincreasing interest as an environmentally friendly alternative to solder interconnection in microelectronics circuit packaging. They are used to attach surface mount devices (SMD), Integrated Circuits (IC) and Flip chips in electronic assembly. The use of ECAs brings some benefits like flexibility, mild processing conditions and process simplicity. Multi walled carbon nanotubes (MWCNT) are used instead of metal fillers because of their novel properties such as light weight, high aspect ratio, corrosion resistant, reduced processing temperature, lead free, good electrical conduction and mechanical strength.

The purpose of the present work is to …

Genetic Algorithm Controlled Common Subexpression Elimination For Spill-Free Register Allocation, Shashi Deepa Arcot

University of Kentucky Master's Theses

As code complexity increases, maxlive increases. This is especially true in the case of the Kentucky If-Then-Else architecture proposed for Nanocontrollers. To achieve low circuit complexity, computations are decomposed to bit-level operations, thus generating large blocks of code with complex dependence structures. Additionally, the Nanocontroller architecture allows for only a small number of single bit registers and no extra memory.

The assumption of an infinite number of registers made during code generation becomes a huge problem during register allocation because the small number of registers and no additional memory. The large basic blocks mean that maxlive almost always exceeds the …

Design And Development Of Structurally Feasible Antennas For Deployment On Inflatable Wings Of Small Unmanned Aerial Vehicles, Rohit Reddy Tammannagari

University of Kentucky Master's Theses

This study is focused on designing conformal antennas to be deployed with the inflatable wings for unmanned aerial vehicles (UAV). The main emphasis is on utilizing the structure of the wing to develop antennas for various frequency bands, while maintaining the wing’s aerodynamic performance. An antenna modeler and optimizer software called 4NEC2 and a program called WIRECODE were used to design and determine the characteristics of the antennas. The effect of flexibility of the inflatable wing on the antenna characteristics during flight is also evaluated.

Real-Time 3-D Reconstruction By Means Of Structured Light Illumination, Kai Liu

University of Kentucky Doctoral Dissertations

Structured light illumination (SLI) is the process of projecting a series of light striped patterns such that, when viewed at an angle, a digital camera can reconstruct a 3-D model of a target object's surface. But by relying on a series of time multiplexed patterns, SLI is not typically associated with video applications. For this purpose of acquiring 3-D video, a common SLI technique is to drive the projector/camera pair at very high frame rates such that any object's motion is small over the pattern set. But at these high frame rates, the speed at which the incoming video can …

Heterojunctions And Schottky Diodes On Semiconductor Nanowires For Solar Cell Applications, Piao Liu

University of Kentucky Doctoral Dissertations

Photovoltaic devices are receiving growing interest in both industry and research institutions due to the great demand for clean and renewable energy. Among all types of solar cells, cadmium sulfide (CdS) – cadmium telluride (CdTe) and cadmium sulfide (CdS) - copper indium diselenide (CuInSe₂ or CIS) heterojunctions based thin film solar cells are of great interest due to their high efficiency and low cost. Further improvement in power conversion efficiency over the traditional device structure can be achieved by tuning the optical and electric properties of the light absorption layer as well as the window layer, utilizing nano template-assisted …

Commercialization And Optimization Of The Pixel Router, Steven James Dominick

University of Kentucky Master's Theses

The Pixel Router was developed at the University of Kentucky with the intent of supporting multi-projector displays by combining the scalability of commercial software solutions with the flexibility of commercial hardware solutions. This custom hardware solution uses a Look Up Table for an arbitrary input to output pixel mapping, but suffers from high memory latencies due to random SDRAM accesses. In order for this device to achieve marketability, the image interpolation method needed improvement as well. The previous design used the nearest neighbor interpolation method, which produces poor looking results but requires the least amount of memory accesses. A cache …

Near-Field Radiative Transfer: Thermal Radiation, Thermophotovoltaic Power Generation And Optical Characterization, Mathieu Francoeur

University of Kentucky Doctoral Dissertations

This dissertation focuses on near-field radiative transfer, which can be defined as the discipline concerned with energy transfer via electromagnetic waves at sub-wavelength distances. Three specific subjects related to this discipline are investigated, namely nearfield thermal radiation, nanoscale-gap thermophotovoltaic (nano-TPV) power generation and optical characterization. An algorithm for the solution of near-field thermal radiation problems in one-dimensional layered media is developed, and several tests are performed showing the accuracy, consistency and versatility of the procedure. The possibility of tuning near-field radiative heat transfer via thin films supporting surface phononpolaritons (SPhPs) in the infrared is afterwards investigated via the computation of …

Linear Actuator Using Shape Memory Wire With Controller, Robert Ryan Vallance, Bruce L. Walcott, James E. Lumpp Jr., Aravind Balasubramanian, Osamah A. Rawashdeh

Electrical and Computer Engineering Faculty Patents

A linear actuator is provided, comprising a housing defining an interior channel, a stop extending from the housing and displaceable relative to the housing, and at least one wire formed of a shape-memory alloy, the wire being attached at a first end to the stop and at a second end to the housing. When heated to a predetermined temperature, the wire applies a pulling force to the stop to cause the stop to slide in a first direction into the housing interior channel. A spring located in the housing interior channel applies a biasing force to the stop in a …

Tunable Laser Interrogation Of Surface Plasmon Resonance Sensors, Vaibhav Badjatya

University of Kentucky Master's Theses

Surface plasmons are bound TM polarized electromagnetic waves that propagate along the interface of two materials with real dielectric constants of opposite signs. Surface plasmon resonance (SPR) sensors make use of the surface plasmon waves to detect refractive index changes occurring near this interface. For sensing purposes, this interface typically consists of a metal layer, usually gold or silver, and a liquid dielectric. SPR sensors usually measure the shift in resonance wavelength or resonance angle due to index changes adjacent to the metal layer. However this restricts the limit of detection (LOD), as the regions of low slope (intensity vs. …

Joint Visual And Wireless Tracking System, Viswajith Karapoondi Nott

University of Kentucky Master's Theses

Object tracking is an important component in many applications including surveillance, manufacturing, inventory tracking, etc. The most common approach is to combine a surveillance camera with an appearance-based visual tracking algorithm. While this approach can provide high tracking accuracy, the tracker can easily diverge in environments where there are much occlusions. In recent years, wireless tracking systems based on different frequency ranges are becoming more popular. While systems using ultra-wideband frequencies suffer similar problems as visual systems, there are systems that use frequencies as low as in those in the AM band to circumvent the problems of obstacles, and exploit …

Direct Electron-Beam Patterning Of Teflon-Af And Its Application To Optical Waveguiding, Vijayasree Karre

University of Kentucky Master's Theses

Thin films of Teflon AF have been directly patterned by electron-beam lithography without the need for post exposure chemical development. The relationship between pattern depth and exposure dose was found to be linear over a wide range of doses. Pattern depth was also observed to be dependent on initial film thickness. Teflon AF can be directly patterned at doses similar to typical e-beam resists. High resolution features as small as ~200 nm have been resolved. FTIR measurements revealed that CF3 and fluorinated dioxole groups play a significant role in the patterning mechanism. Teflon AF films also exhibited an increase in …

Enhancements To The Generalized Sidelobe Canceller For Audio Beamforming In An Immersive Environment, Phil Townsend

University of Kentucky Master's Theses

The Generalized Sidelobe Canceller is an adaptive algorithm for optimally estimating the parameters for beamforming, the signal processing technique of combining data from an array of sensors to improve SNR at a point in space. This work focuses on the algorithm’s application to widely-separated microphone arrays with irregular distributions used for human voice capture. Methods are presented for improving the performance of the algorithm’s blocking matrix, a stage that creates a noise reference for elimination, by proposing a stochastic model for amplitude correction and enhanced use of cross correlation for phase correction and time-difference of arrival estimation via a correlation …