Electrical and Computer Engineering Commons^™

Development Of A Reusable Cubesat Satellite Bus Architecture For The Kysat-1 Spacecraft, Tyler James Doering

University of Kentucky Master's Theses

This thesis describes the design, implementation and testing of a spacecraft bus implemented on KySat-1, a picosatellite scheduled to launch late 2009 to early 2010. The spacecraft bus is designed to be a robust reusable bus architecture using commercially available off the shelf components and subsystems. The bus designed and implemented for the KySat-1 spacecraft will serve as the basis for a series of future Kentucky Space Consortium missions. The spacecraft bus consists of attitude determination and control subsystem, communications subsystem, command and data handling subsystem, thermal subsystem, power subsystem, and structures and mechanisms. The spacecraft bus design is described …

Fabrication Of Nanostructures For Improved Performance Of Electrochemical Sensors And For Reference Compensation In Localized Surface Plasmon Resonance Sensors, Prashanthi Para

University of Kentucky Master's Theses

L‐glutamate is associated with several neurological disorders; thus, monitoring fast dynamics of L‐glutamate is of great importance in the field of neuroscience. Electrode miniaturization demanded by many applications leads to reduced surface area and decreased amounts of immobilized enzymes on coated electrodes. As a result, lower signal‐to‐noise ratios are observed for oxidase‐enzyme based sensors. To increase the signal‐to‐noise ratio we have developed a process to fabricate micro‐ and nano‐ structures on the microelectrode surface.

Localized surface‐plasmon resonances (SPR) has been extensively used to design label‐free biosensors that can monitor receptor‐ligand interactions. A major challenge with localized SPR sensors is that …

Performance Of Pan-Tilt Tracker Based On The Pin-Hole Lens Model, Vikas Chandra Mehta

University of Kentucky Master's Theses

In the modern day, recognition and tracking of face or the iris is potentially one of the most powerful ways of differentiating between an authentic person and an imposter. Our method uses stereo vision to track the 3-Dimensional coordinates of a target equivalent to a person’s eyes and using a pan-tilt unit we target these areas for additional processing such as iris or facial imaging. One of the most important parts involved in tracking is the way the pan-tilt unit is calibrated. There have been techniques in the past where PTZ (Pan-tilt-zoom) digital camera has been used and calibrated using …

Impact Of Microphone Positional Errors On Speech Intelligibility, Arulkumaran Muthukumarasamy

University of Kentucky Master's Theses

The speech of a person speaking in a noisy environment can be enhanced through electronic beamforming using spatially distributed microphones. As this approach demands precise information about the microphone locations, its application is limited in places where microphones must be placed quickly or changed on a regular basis. Highly precise calibration or measurement process can be tedious and time consuming. In order to understand tolerable limits on the calibration process, the impact of microphone position error on the intelligibility is examined. Analytical expressions are derived by modeling the microphone position errors as a zero mean uniform distribution. Experiments and simulations …

Reduced Frequency Motor Starting For Third World Power Systems, Taylor A. Begley

University of Kentucky Master's Theses

People in modern industrialized societies live a blessed life relative to those who do not when it comes to some modern conveniences. While many think nothing of flipping on a light switch or running electric appliances, there are people in third world countries could not imagine such things. As service projects are being undertaken to bring such conveniences to those less fortunate, there often is the harsh reality of a strict budget. An item that commands a large portion of said budget is often the diesel generator used to provide the facility with electricity. Generators serving motor loads are typically …

Verification And Debug Techniques For Integrated Circuit Designs, David Allen Crutchfield

University of Kentucky Master's Theses

Verification and debug of integrated circuits for embedded applications has grown in importance as the complexity in function has increased dramatically over time. Various modeling and debugging techniques have been developed to overcome the overwhelming challenge. This thesis attempts to address verification and debug methods by presenting an accurate C model at the bit and algorithm level coupled with an implemented Hardware Description Language (HDL). Key concepts such as common signal and variable naming conventions are incorporated as well as a stepping function within the implemented HDL. Additionally, a common interface between low-level drivers and C models is presented for …

Separating Instruction Fetches From Memory Accesses : Ilar (Instruction Line Associative Registers), Nien Yi Lim

University of Kentucky Master's Theses

Due to the growing mismatch between processor performance and memory latency, many dynamic mechanisms which are “invisible” to the user have been proposed: for example, trace caches and automatic pre-fetch units. However, these dynamic mechanisms have become inadequate due to implicit memory accesses that have become so expensive. On the other hand, compiler-visible mechanisms like SWAR (SIMD Within A Register) and LARs (Line Associative Registers) are potentially more effective at improving data access performance. This thesis investigates applying the same ideas to improve instruction access.

ILAR (Instruction LARs) store instructions in wide registers. Instruction blocks are explicitly loaded into ILAR, …

Micro-Fabricated Hydrogen Sensors Operating At Elevated Temperatures, Chi Lu

University of Kentucky Doctoral Dissertations

In this dissertation, three types of microfabricated solid-state sensors had been designed and developed on silicon wafers, aiming to detect hydrogen gas at elevated temperatures. Based on the material properties and sensing mechanisms, they were operated at 140°C, 500°C, and 300°C. The MOS-capacitor device working at 140°C utilized nickel instead of the widely-used expensive palladium, and the performance remained excellent. For very-high temperature sensing (500°C), the conductivity of the thermally oxidized TiO₂ thin film based on the anodic aluminum oxide (AAO) substrate changed 25 times in response to 5 ppm H₂ and the response transient times were just …

Electrical And Mechanical Properties Of Mwcnt Filled Conductive Adhesives On Lead Free Surface Finished Pcb's., Keerthi Varma Mantena

University of Kentucky Master's Theses

Electrically conductive adhesives (ECA) are an alternative to tin/lead solders for attaching Surface Mount Devices (SMD) in electronic assemblies. ECAs are mixtures of a polymer binder (for adhesion) and conductive filler (for electrical conductivity). They bring more conductivity, higher strength, less weight and longer durability than metal alloys. ECAs can offer numerous advantages such as fewer processing steps, lower processing temperature and fine pitch capability. Multi walled carbon nanotubes (MWCNT) were used as conductive fillers in this research because of their novel electronic and mechanical properties.

The high aspect ratio of the nanotubes makes it possible to percolate at low …

Mpi Within A Gpu, Bobby Dalton Young

University of Kentucky Master's Theses

GPUs offer high-performance floating-point computation at commodity prices, but their usage is hindered by programming models which expose the user to irregularities in the current shared-memory environments and require learning new interfaces and semantics.

This thesis will demonstrate that the message-passing paradigm can be conceptually cleaner than the current data-parallel models for programming GPUs because it can hide the quirks of current GPU shared-memory environments, as well as GPU-specific features, behind a well-established and well-understood interface. This will be shown by demonstrating a proof-of-concept MPI implementation which provides cleaner, simpler code with a reasonable performance cost. This thesis will also …

Collective Communication And Barrier Synchronization On Nvidia Cuda Gpu, Diego Alejandro Rivera-Polanco

University of Kentucky Master's Theses

GPUs (Graphics Processing Units) employ a multi-threaded execution model using multiple SIMD cores. Compared to use of a single SIMD engine, this architecture can scale to more processing elements. However, GPUs sacrifice the timing properties which made barrier synchronization implicit and collective communication operations fast.

This thesis demonstrates efficient methods by which these aggregate functions can be implemented using unmodified NVIDIA CUDA GPUs. Although NVIDIA's highest “compute capability" GPUs provide atomic memory functions, they have order N execution time. In contrast, the methods proposed here take advantage of basic properties of the GPU architecture to make implementations that are both …

Design And Analysis Of Nano-Gap Enhanced Surface Plasmon Resonance Sensors, Phillip Donald Keathley

University of Kentucky Master's Theses

Surface plasmon resonance (SPR) sensors are advantageous to other techniques of sensing chemical binding, offering quantitative, real-time, label-free results. Previous work has demonstrated the effectiveness of using dual-mode SPR sensors to differentiate between surface and background effects, making the sensors more robust to dynamic environments. This work demonstrates a technique that improves upon a previously optimized planar film dual-mode SPR sensor’s LOD by introducing a periodic array of subwavelength nano-gaps throughout the plasmon supporting material. First, general figures of merit for a sensor having an arbitrary number of modes are studied. Next, the mode effective index dispersion and magnetic field …

System And Technique For Retrieving Depth Information About A Surface By Projecting A Composite Image Of Modulated Light Patterns, Laurence G. Hassebrook, Daniel L. Lau, Chun Guan

Electrical and Computer Engineering Faculty Patents

A technique, associated system and program code, for retrieving depth information about at least one surface of an object. Core features include: projecting a composite image comprising a plurality of modulated structured light patterns, at the object; capturing an image reflected from the surface; and recovering pattern information from the reflected image, for each of the modulated structured light patterns. Pattern information is preferably recovered for each modulated structured light pattern used to create the composite, by performing a demodulation of the reflected image. Reconstruction of the surface can be accomplished by using depth information from the recovered patterns to …

Gas Sensing Properties And Transport Properties Of Multi Walled Carbon Nanotubes, Raghu Mangu

University of Kentucky Master's Theses

Multi walled carbon nanotubes (MWCNT) grown in highly ordered porous alumina templates were incorporated into a resistive gas sensor design and were evaluated for their sensitivities. The material characteristics and electrical properties of the nanotubes were analyzed. A study was undertaken to elucidate the effect of UV light on desorption characteristics and the dependence of sensitivity on (i) thickness of amorphous carbon layers and (ii) flow rates of analyte gases. These sensors were highly responsive to both oxidizing and reducing gases with steady state sensitivities of 5% and 10% for 100ppm of NH₃ and NO₂ respectively, at room …

Photovoltaic Cells Based On Copper Phthalocyanine And Cadmium Sulfide Heterojunction, Sandeep Kumar Marda

University of Kentucky Master's Theses

This work focuses on the solar cell based on the heterostructure formed between Copper Phthalocyanine (CuPc) and Cadmium Sulfide (CdS). Two different fabrication techniques were used for depositing the organic and inorganic layers of CuPc and CdS layers respectively. CuPc was deposited by electrodeposition while CdS was deposited by chemical bath deposition. Hybrid CdS/CuPc thin films were obtained from CdS films grown on Glass/ITO by chemical bath deposition followed by electrodeposition of CuPc onto these films and annealing at 250˚C after the deposition of each layer. The maximum open circuit voltage (V_oc) and the short circuit current density …

A Highly Reliable Non-Volatile File System For Small Satellites, Rama Krishna Nimmagadda

University of Kentucky Master's Theses

Recent Advancements in Solid State Memories have resulted in packing several Giga Bytes (GB) of memory into tiny postage stamp size Memory Cards. Of late, Secure Digital (SD) cards have become a de-facto standard for all portable handheld devices. They have found growing presence in almost all embedded applications, where huge volumes of data need to be handled and stored.

For the very same reason SD cards are being widely used in space applications also. Using these SD Cards in space applications requires robust radiation hardened SD cards and Highly Reliable Fault Tolerant File Systems to handle them. The present …

Color Multiplexed Single Pattern Sli, Neelima Mandava

University of Kentucky Master's Theses

Structured light pattern projection techniques are well known methods of accurately capturing 3-Dimensional information of the target surface. Traditional structured light methods require several different patterns to recover the depth, without ambiguity or albedo sensitivity, and are corrupted by object movement during the projection/capture process. This thesis work presents and discusses a color multiplexed structured light technique for recovering object shape from a single image thus being insensitive to object motion.

This method uses single pattern whose RGB channels are each encoded with a unique subpattern. The pattern is projected on to the target and the reflected image is captured …

Motion Correction Structured Light Using Pattern Interleaving Technique, Raja Kalyan Ram Cavaturu

University of Kentucky Master's Theses

Phase Measuring Profilometry (PMP) is the most robust scanning technique for static 3D data acquisition. To make this technique robust to the target objects which are in motion during the scan interval a novel algorithm called ‘Pattern Interleaving’ is used to get a high density single scan image and making Phase Measuring Profilometry insensitive to ‘z’ motion and prevent motion banding which is predominant in 3D reconstruction when the object is in motion during the scan time

Schottky Diodes On Copper Phthalocyanine Nanowire Arrays Embedded In Porous Alumina Templates, Goutam Chintakula

University of Kentucky Master's Theses

Vertically aligned nanowire arrays of copper phthalocyanine (CuPc) and CuPc-Al Schottky diodes, of controllable diameter and length were fabricated by cathodic electrodeposition of CuPc into anodized alumina (AAO) templates, followed by annealing at 300 ºC in Argon. AAO over Aluminum tape and that over ITO-glass were both used as starting templates for the device fabrication. Depending on the dimensions of the starting AAO template, diameters of CuPc nanowires ranged from 30 nm to 40 nm and the lengths ranged from 500 nm to 1 μm. The temperature dependence of the phase and the absorption spectrum of the nanowires are reported. …

Phonon-Energy-Coupling-Enhancement Effect And Its Applications, Pang-Leen Ong

University of Kentucky Doctoral Dissertations

Silicon Oxide/Oxynitride (SiO₂/SiON) has been the mainstream material used for gate dielectric for MOS transistors for the past 30 years. The aggressive scaling of the feature size of MOS transistor has limited the ability of SiO₂/SiON to work effectively as the gate dielectric to modulate the conduction of current of MOS transistors due to excess leakage current dominated by direct quantum tunneling. Due to this constraint, alternative gate dielectric/high-k is being employed to reduce the leakage current in order to maintain the rate of scaling of MOS transistors. However, the cost involved in the implementation of …

Dual Bypass Gas Metal Arc Welding Process And Control, Xiaopei Liu

University of Kentucky Doctoral Dissertations

GMAW (Gas Metal Arc Welding) is one of the most important arc welding processes being adopted in modern manufacturing industry due to its advantages in productivity, energy efficiency and automation. By monitoring and improving some of the important properties of GMAW such as production rate, metal transfer and base metal heat input, researchers could bring the process efficiency and stability to a new level. In recent years, some innovative modifications of GMAW such as Twins, Tandem and laser-MIG hybrid welding have been adopted into many industrial applications for better productivity.

In this dissertation, a novel GMAW called DB-GMAW (Dual Bypass …

Modeling And Analysis Of Split And Merge Production Systems, Yang Liu

University of Kentucky Master's Theses

Many production systems have split and merge operations to increase production capac- ity and variety, improve product quality, and implement product control and scheduling policies. This thesis presents analytical methods to model and analyze split and merge production systems with Bernoulli and exponential reliability machines under circulate, priority and percentage policies. The recursive procedures for performance analysis are de- rived, and the convergence of the procedures and uniqueness of the solutions, along with the structural properties, are proved analytically, and the accuracy of the estimation is justi¯ed numerically with high precision. In addition, comparisons among the e®ects of di®erent policies …

Stranded Core Transformer Loss Analysis, Xingxing Zhang

University of Kentucky Master's Theses

We will present the approaches used to investigating the power loss for the stranded core transformers. One advantage of using stranded core is to reduce power loss or enhance transformer efficiency. One difficulty in the modeling of this type of transformer is that the core is not solid (there are small gaps between core wires due to circular cross section). A two dimensional finite element method with nodal basis function for magnetostatic field was developed to study the effects of the small gaps between core wires. The magnetic flux densities are compared for the uniform (solid) cores and the stranded …

Hdl Implementation And Analysis Of A Residual Register For A Floating-Point Arithmetic Unit, Akil Kaveti

University of Kentucky Master's Theses

Processors used in lower-end scientific applications like graphic cards and video game consoles have IEEE single precision floating-point hardware [23]. Double precision offers higher precision at higher implementation cost and lower performance. The need for high precision computations in these applications is not enough to justify the use double precision hardware and the extra hardware complexity needed [23]. Native-pair arithmetic offers an interesting and feasible solution to this problem. This technique invented by T. J. Dekker uses single-length floating-point numbers to represent higher precision floating-point numbers [3]. Native-pair arithmetic has been proposed by Dr. William R. Dieter and Dr. Henry …

Super Resolution 3d Scanning Using Spatial Light Modulator And Band Correction, Akshay Pethe

University of Kentucky Master's Theses

Multi Frequency Phase Measuring Profilometry is the most popular lateral contact 3-D Scanning technique. The Phase Measuring Profilometry is limited in resolution by the projector and cameras used. Conventional signal projectors have a maximum of 2000 to 4000 scan lines limiting the projector resolution. To obtain greater detail with higher resolution the PMP technique is applied to a Spatial Light Modulator (SLM) having 12000 lines, very large as compared to conventional projectors. This technology can achieve super resolution scans having varied applications. Scans achieved from PMP suffer from a certain type of artifact called “banding” which are periodic bands across …

Role Of Dipoles In The Bulk Phosphor Layer In The Electroluminance Mechanisms Of A.C. Thin Film Electroluminescent Display Devices, Praveen Kumar Sivakumar

University of Kentucky Doctoral Dissertations

The purpose of this dissertation is to advance the understanding of SrS-based a. c. thin film electroluminescent (ACTFEL) devices. The role of traps in the bulk phosphor layer in the light emission mechanism from ACTFEL devices is studied, characterized and modeled.

Experiments were performed to observe the response of the ACTFEL devices to tailored voltage excitations. A physical model was developed to describe the optoelectronic processes taking place in the phosphor; analytical equations were written and numerically simulated to plot the flux and luminance responses of the device to similarly tailored voltage excitations.

The voltage excitation parameters such as amplitude, …

Thevenin Equivalent Circuit Estimation And Application For Power System Monitoring And Protection, Mohammad M. Iftakhar

University of Kentucky Master's Theses

The Estimation of Thevenin Equivalent Parameters is useful for System Monitoring and Protection. We studied a method for estimating the Thevenin equivalent circuits. We then studied two applications including voltage stability and fault location. A study of the concepts of Voltage Stability is done in the initial part of this thesis. A Six Bus Power System Model was simulated using MATLAB SIMULINK®. Subsequently, the Thevenin Parameters were calculated. The results were then used for two purposes, to calculate the Maximum Power that can be delivered and for Fault Location.

Nanostructured Thin Films And Tubes Of Titania For Room Temperature Sensing Of Gases, Satish Kumar Kandala

University of Kentucky Master's Theses

The main objective of this work was to study the applicability of Nano porous/Nanocrystalline TiO₂ films for serving the growing demand for fast accurate and low cost air quality analysis techniques. The sensitivity of response to variations in microstructure pointed the way to obtain controlled, reproducible and regular microstructures with critical dimensions proportionate with the Debye- length of the oxide. This work aimed to study the sensor properties of thin films of Nanocrystalline Titania and Titania nanotubes at room temperature. Nano porous/Nanocrystalline TiO₂ films were fabricated through evaporation driven convection/sol-gel method by controlling the process conditions. We also …

Synthesis And Characterization Of Schottky Diodes On N-Type Cdte Nanowires Embedded In Porous Alumina Templates, Srikanth Yanamanagandla

University of Kentucky Master's Theses

This work focuses on the growth of vertically aligned CdTe nanowire arrays of controllable diameter and length using cathodic electro deposition in anodized alumina templates. This step was followed by annealing at 250° C in a reducing environment (95% Ar + 5% H2). AAO template over ITO-glass was used as starting template for the device fabrication. The deposited nanowires showed nanocrystalline cubic phase structures with a strong preference in [111] direction. First gold (Au) was deposited into AAO using cathodic electro deposition. This was followed by CdTe deposition into the pore. Gold was deposited first as it aids the growth …

Modular Fast Direct Analysis Using Non-Radiating Local-Global Solution Modes, Xin Xu

University of Kentucky Doctoral Dissertations

This dissertation proposes a modular fast direct (MFD) analysis method for a class of problems involving a large fixed platform region and a smaller, variable design region. A modular solution algorithm is obtained by first decomposing the problem geometry into platform and design regions. The two regions are effectively detached from one another using basic equivalence concepts. Equivalence principles allow the total system model to be constructed in terms of independent interaction modules associated with the platform and design regions. These modules include interactions with the equivalent surface that bounds the design region. This dissertation discusses how to analyze (fill …