Engineering Commons^™

Characterization Of An Inductively Coupled Plasma Produced In Argon At 13.56 Mhz., Lim Ai Nuan

Student Works (2010-2019)

The electrical and plasma characteristics of radio frequency (13.56 MHz) inductively coupled argon plasma (RF ICP) were studied in this project. On the electrical breakdown properties, the breakdown voltage has a general appearance of Paschen’s curve and the minimum is achieved at 0.1 mbar. After ignition, two modes of discharge exist, namely, the E mode at low RF power and H mode at high RF power. Mode transition that occurs is accompanied by abrupt changes in both electrical and plasma characteristics. Hysteresis is observed in the mode transitions and has a minimum at 0.1 mbar. The resistance reflected into the …

Black Carbon Over Mexico: The Effect Of Atmospheric Transport On Mixing State, Mass Absorption Cross-Section, And Bc/Co Ratios, R. Subramanian, G. L. Kok, D. Baumgardner, A. Clarke, Y. Shinozuka, T. L. Campos, C. G. Heizer, B. B. Stephens, B. De Foy, Paul B. Voss, R. A. Zaveri

Engineering: Faculty Publications

A single particle soot photometer (SP2) was operated on the NCAR C-130 during the MIRAGE campaign (part of MILAGRO), sampling black carbon (BC) over Mexico. The highest BC concentrations were measured over Mexico City (sometimes as much as 2μg/m3) and over hillfires to the south of the city. The age of plumes outside of Mexico City was determined using a combination of HYSPLIT trajectories, WRF-FLEXPART modeling and CMET balloon tracks. As expected, older, diluted air masses had lower BC concentrations. A comparison of carbon monoxide (CO) and BC suggests a CO background of around 65 ppbv, and a background-corrected BC/COnet …

Drafting A Blueprint For Educating Tomorrow's Engineers Today, Beth Mcginnis-Cavanaugh, Glenn Ellis, Diana Fiumefreddo

Engineering: Faculty Publications

No abstract provided.

Weight, Weight, Don't Tell Me! A Single Measurement, Graphical Approach To The Study Of The Motion Of An Elevator, Warren Turner, Glenn Ellis

Engineering: Faculty Publications

No abstract provided.

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 …

Multiwall Carbon Nanotubes Alter The Thermal Profile And Antibiotic Elution Of Orthopaedic Bone Cement, Alison Carroll Tickle

University of Kentucky Master's Theses

Multiwall carbon nanotubes (MWNTs) have extraordinary mechanical and thermal transport properties. They significantly improve the static and dynamic mechanical properties of acrylic orthopaedic bone cement when added to the dry cement polymer powder. Understanding the role MWNTs play on bone cement polymerization temperatures will lead to improved mechanical integrity of the cement-bone interface in joint arthroplasties. It was determined through thermal testing that MWNTs increased the polymerization time of the methylmethacrylate by 45-460% and decreased the peak exothermic temperature of bone cement with and without antibiotics. The flow of heat produced during polymerizing cement was reduced 25-85% with the addition …

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.

Comparison Of Stabilization Methods For Fixed-Speed Wind Generator Systems, Mohammod Ali, Bin Wu

Faculty Publications

Static Synchronous Compensator (STATCOM), Pitch control system, Braking Resistor (BR), and Superconducting Magnetic Energy Storage (SMES) have recently been reported as stabilization methods for fixed-speed wind generator systems. although the individual technologies are well documented, a comparative study of these systems has not been reported so far. This paper aims to fill in the gap, and provides a comprehensive analysis of these stabilization methods for fixed-speed wind generator systems. The analysis is performed in terms of transient stability enhancement, controller complexity, and cost. a novel feature of this work is that the transient stability analysis of wind generator system is …

High Frequency Vco And Frequency Divider In Vlsi 90nm Technology, Paesol Veerakitti

Browse all Theses and Dissertations

A Voltage Controlled Oscillator (VCO) is essentially a tunable frequency generator. A VCO is used as a part in PLL system which is a system that generates a stable oscillating signal. As the digital electronic industry demands an ever increasing performance in speed, VCO's are required to create higher frequency signals. However, the phase noise performance of a VCO decreases as the operating frequency gets higher. The LC VCO is developed in this thesis to be used in with a tunable frequency divider as a part of a PLL system. The LC VCO structure design takes the advantage of a …

Arsenite Oxidation By Pure Cultures Of Thiomonas Arsenivorans Strain B6 In Bioreactor Systems, Aniruddha Dastidar

University of Kentucky Doctoral Dissertations

The removal of arsenic toxicity from water is accomplished by a preliminary preoxidative step transforming the most toxic form, arsenite (As (III)), to the least toxic form, arsenate (As (V)). The potential of As (III) oxidation to As (V) was initially investigated in batch reactors using the chemoautotrophic Thiomonas arsenivorans strain b6 under varying initial As (III) and cell concentrations and at optimal pH and temperature conditions (pH 6.0 and temperature 30°C). The strain b6 completely oxidized As (III) to As (V) during exponential growth phase for lower levels of As (III) concentrations (≤ 100 mg/L) but continued into stationary …

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 …

Dynamics Of Fibrillar Precursors Of Shishes As A Function Of Stress, Luigi Balzano, Dario Cavallo, Tim B. Van Erp, Zhe Ma, Jan-Willem Housmans, Lucia Fernandez-Ballester, Gerrit W. M. Peters

Department of Engineering Mechanics: Faculty Publications

Shishes are fibrillar crystallites that can be created by deforming a polymer melt. The formation of shishes takes place when flow is strong enough to stretch molecules. In the early stages, bundles of stretched molecules with pre-crystalline order form metastable precursors whose stability depends on their size and, hence, on the stress level. We find that for a specific isotactic polypropylene, close to the nominal melting point, a stress larger than 0.10 MPa leads to stable fibrillar precursors that are partially crystalline immediately after flow. On the other hand, below 0.10 MPa, the aspect ratio of precursors tends to unity …

A Non-Vacuum Process For Preparing Nanocrystalline Cuin1−XGaXSe2 Materials Involving An Open-Air Solvothermal Reaction, J. Olejníček, Chad A. Kamler, A. Mirasano, A. L. Martinez-Skinner, M. A. Ingersoll, C. L. Exstrom, S. A. Darveau, J. L. Huguenin-Love, M. Diaz, Natale J. Ianno, Rodney J. Soukup

Department of Electrical and Computer Engineering: Faculty Publications

A non-vacuum, two-step process has been used to prepare a series of nanocrystalline CuIn_1−xGa_xSe₂ (x = 0, 0.25, 0.5, 0.75, 1) materials. An open-air solvothermal preparation in triethylenetetramine solvent was followed by annealing at 500 °C in a nitrogen atmosphere for 20 min. All materials have mixed clustered plate, spherical particle, and nanorod morphologies with the smallest particle diameters ranging between 20 and 40 nm. Raman spectroscopy and X-ray diffraction (XRD) confirm that indium/gallium ratio control is possible over a wide range. The solvothermal reaction step yields a mixture of chalcopyrite and Cu …

Interface Polarization Coupling In Piezoelectric-Semiconductor Ferroelectric Heterostructures, Venkata M. Voora, Tino Hofmann, M. Brandt, M. Lorenz, M. Grundmann, N. Ashkenov, H. Schmidt, Natale J. Ianno, Mathias Schubert

Department of Electrical and Computer Engineering: Faculty Publications

We present a dielectric continuum model approach for studying the electrical polarization properties of interface polarization coupled BaTiO₃, BaTiO₃-ZnO, and ZnO-BaTiO₃-ZnO thin-film structures consisting of several hundred nanometer thick layers. Our model augments the effects of electric field driven switchable polarization and depletion layer formation with spontaneous interface polarization coupling. Wurtzite-structure (piezoelectric) n-type ZnO and perovskite-structure (ferroelectric) highly insulating BaTiO₃ layers were prepared and investigated. The coupling between the nonswitchable spontaneous polarization of ZnO and the electrically switchable spontaneous polarization of BaTiO₃ causes strong asymmetric polarization hysteresis behavior. The n-type ZnO reveals …

Hydrogen In Inn: A Ubiquitous Phenomenon In Molecular Beam Epitaxy Grown Material, V. Darakchieva, K. Lorenz, N. P. Barradas, E. Alves, B. Monemar, Mathias Schubert, N. Franco, C. L. Hsiao, L. C. Chen, W. J. Schaff, L. W. Tu, T. Yamaguchi, Y. Nanishi

Department of Electrical and Computer Engineering: Faculty Publications

We study the unintentional H impurities in relation to the free electron properties of state-of-the-art InN films grown by molecular beam epitaxy (MBE). Enhanced concentrations of H are revealed in the near surface regions of the films, indicating postgrowth surface contamination by H. The near surface hydrogen could not be removed upon thermal annealing and may have significant implications for the surface and bulk free electron properties of InN. The bulk free electron concentrations were found to scale with the bulk H concentrations while no distinct correlation with dislocation density could be inferred, indicating a major role of hydrogen for …

Secure Communication Over Fading Channels With Statistical Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, secure transmission of information over an ergodic fading channel is studied in the presence of statistical quality of service (QoS) constraints.We employ effective capacity to measure the secure throughput of the system, i.e., effective secure throughput. We assume that the channel side information (CSI) of the main and the eavesdropper channels is available at the transmitter side. Under this assumption, we investigate the optimal power control policies that maximize the effective secure throughput. In particular, it is noted that opportunistic transmission is no longer optimal and the transmitter should not wait to send the data at …

A Noncooperative Power Control Game In Multiple-Access Fading Channels With Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, a game-theoretic analysis for the resource allocation policies in fading multiple-access channels (MAC) in the presence of quality of service (QoS) constraints is performed. Effective capacity, which provides the maximum constant arrival rate, or throughput, that a given service process can support while satisfying statistical delay constraints, is considered in a multiuser scenario. We assume that the channel side information (CSI) is available at both the receiver and transmitters, and the transmitters are selfish, rational with certain QoS constraints and average power limitations. Without the aid of the receiver, we prove that there is always a unique …

A Grammar-Based Distance Metric Enables Fast And Accurate Clustering Of Large Sets Of 16s Sequences, David J. Russell, Samuel F. Way, Andrew K. Benson, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: We propose a sequence clustering algorithm and compare the partition quality and execution time of the proposed algorithm with those of a popular existing algorithm. The proposed clustering algorithm uses a grammar-based distance metric to determine partitioning for a set of biological sequences. The algorithm performs clustering in which new sequences are compared with cluster-representative sequences to determine membership. If comparison fails to identify a suitable cluster, a new cluster is created.

Results: The performance of the proposed algorithm is validated via comparison to the popular DNA/RNA sequence clustering approach, CD-HIT-EST, and to the recently developed algorithm, …

Protein Adsorption On And Swelling Of Polyelectrolyte Brushes: A Simultaneous Ellipsometry-Quartz Crystal Microbalance Study, Eva Bittrich, Keith B. Rodenhausen Jr., Klaus-Jochen Eichhorn, Tino Hofmann, Mathias Schubert, Manfred Stamm, Petra Uhlmann

Department of Electrical and Computer Engineering: Faculty Publications

With a coupled spectroscopic ellipsometry-quartz crystal microbalance with dissipation (QCM-D) experimental setup, quantitative information can be obtained about the amount of buffer components (water molecules and ions) coupled to a poly(acrylic acid) (PAA) brush surface in swelling and protein adsorption processes. PAA Guiselin brushes with more than one anchoring point per single polymer chain were prepared. For the swollen brushes a high amount of buffer was found to be coupled to the brush-solution interface in addition to the content of buffer inside the brush layer. Upon adsorption of bovine serum albumin the further incorporation of buffer molecules into the protein-brush …

Tob1 Is A Constitutively Expressed Repressor Of Liver Regeneration, Karen J. Ho, Nhue L. Do, Hasan H. Otu, Martin J. Dib, Xianghui Ren, Keiichi Enjyoji, Simon C. Robson, Ernest F. Terwilliger, Seth J. Karp

Department of Electrical and Computer Engineering: Faculty Publications

How proliferative and inhibitory signals integrate to control liver regeneration remains poorly understood. A screen for antiproliferative factors repressed after liver injury identified transducer of ErbB2.1 (Tob1), a member of the PC3/BTG1 family of mito-inhibitory molecules as a target for further evaluation. Tob1 protein decreases after 2/3 hepatectomy in mice secondary to posttranscriptional mechanisms. Deletion of Tob1 increases hepatocyte proliferation and accelerates restoration of liver mass after hepatectomy. Down-regulation of Tob1 is required for normal liver regeneration, and Tob1 controls hepatocyte proliferation in a dose-dependent fashion. Tob1 associates directly with both Caf1 and cyclindependent kinase (Cdk) 1 and …

Iterative Signal Processing In Communications, Christian Schlegel, Peter Hoeher, Owe Axelsson, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

Iterative signal processing in communications has experienced an explosive rise in popularity in recent years. The catalytic origins of this paradigm-shifting new philosophy among communications experts can be traced to the invention of turbo coding, and the subsequent rediscovery of low-density parity check (LDPC) coding, both in the field of error control coding. Both systems rely on iterative decoding algorithms to achieve their astounding performance. However, iterative signal processing is not confined to the decoding of error control codes and rather quickly spread to many other possible applications. The purpose of this special issue is to examine the concept of …