Digital Commons Network^™

The Effect Of Component Recognition On Flexibility And Speech Recognition Performance In A Spoken Question Answering System, Mike Dalton

Doctoral Dissertations

A spoken question answering system that recognizes questions as full sentences performs well when users ask one of the questions defined. A system that recognizes component words and finds an equivalent defined question might be more flexible, but is likely to have decreased speech recognition performance, leading to a loss in overall system success. The research described in this document compares the advantage in flexibility to the loss in recognition performance when using component recognition.

Questions posed by participants were processed by a system of each type. As expected, the component system made frequent recognition errors while detecting words (word …

Surface Structure And Composition Determination By Low-Energy Electron Scattering And Monte Carlo Simulations, Jiebing Sun

Doctoral Dissertations

This thesis reports on surface and surface alloy structural and compositional determination with low-energy electron scattering and Monte Carlo simulations. Low-energy electron diffraction (LEED) technique and the newly developed low-energy electron microscopy (LEEM) IV technique are used to measure the electron scattering intensity spectra and dynamical multiple scattering analysis is performed to optimize the surface structural and non-structural parameters via comparison between the experimental spectra and calculated ones. My work focuses on the following four surface systems.

(111), (110) and (001) surface structures of the semimetal bismuth are determined with LEED. The unreconstructed (1x1) structure is revealed for all three …

Texture Evolution In Metal Nitride (Aluminum Nitride, Titanium Nitride, Hafnium Nitride) Thin Films Prepared By Off-Normal Incidence Reactive Magnetron Sputtering, Derya Deniz

Doctoral Dissertations

We studied the development of crystallographic texture in aluminum nitride (AlN), titanium nitride (TiN) and hafnium nitride (HfN) films deposited by off-normal incidence reactive magnetron sputtering at room temperature in N2/Ar mixtures. Texture measurements were performed by x-ray pole figure analysis of the (0002) (AlN), (111) and (200) (TiN and HfN) diffraction peaks. We report a strong dependence of fiber texture tilt angle on the angle of deposition and gas composition in AlN. We present a Monte Carlo simulation model to describe the phenomenon of sudden c-axis (0002) AIN tilt. The model is based on the competition among grains with …

Improved Estimation Of Fourier Coefficients For Ill-Posed Inverse Problems, Mikhail V. Shubov

Doctoral Dissertations

In this dissertation we present and solve an ill-posed inverse problem which involves reproducing a function f(x) or its Fourier coefficients from the observed values of the function. The observations of the f(x) are made at n equidistant points on the unit interval with p observations being made at each point. The observations are effected by a random error with a known distribution.

First of all we present a very simple estimator for the Fourier coefficients of f(x). Then we present an iteration algorithm for improving the estimator for the Fourier coefficients. We show that the improved estimator we use …

Evaluation Of Reactive Cap Sorbents For In-Situ Remediation Of Contaminated Sediments, Bhawana Sharma

Doctoral Dissertations

Contaminated sediments can be treated using in-situ treatment methods that aim to either degrade or sequester contaminants, reducing their bioavailability. The main purpose of this research was to develop and evaluate a reactive capping mat that can be used for in-situ remediation of contaminated sediments. This study investigated the interferences caused by humic acid on the adsorption of co-planar and non-co-planar polychlorinated biphenyls (PCBs) including 2-chlorobiphenyl, 2, 2', 5, 5'-tetrachlorobiphenyl, 3, 3', 4, 4'-tetrachlorobiphenyl, 2, 2', 4, 4', 5, 5'-hexachlorobiphenyl and 3, 3', 4, 4', 5, 5'-hexachlorobiphenyl and polycyclic aromatic hydrocarbons (PAHs) including naphthalene, phenanthrene and pyrene on two types …

Synthesis Of Unsymmetrical Pendant-Armed And Phosphonic Acid-Pendant-Armed Cross-Bridged Tetraazamacrocycles, Dannon Jason Stigers

Doctoral Dissertations

The synthesis of a variety of cross-bridged tetraazamacrocycles bearing phosphonate pendant arms and their corresponding phosphonic acid derivatives as well as their Cu(II) complexes are presented. The half-life of decomplexation of Cu(II)·51 in 5M HCl at 90°C was found to be 3.8 hours. Ligand 51 showed faster complexation kinetics relative to known cross-bridged tetraazamacrocycles bearing ionizable pendant arms. The biodistribution of 64Cu(II)·51 was studied in male rats and indicated an improved blood and liver clearance and higher bone retention of 64Cu(II)·51 relative to 64Cu(II)·10.*.

The formation of a single pendant-armed cross-bridged cyclam is presented through an unusual single alkylation of …

Conserving Dolphins And Fishermen: Combining Science And Local Knowledge To Reduce Cetacean Bycatch, Erika A. Zollett

Doctoral Dissertations

Bycatch is the portion of catch that is neither targeted nor retained by fishermen. It threatens the survival of many marine mammal populations globally, and it occurs in nearly every fishing gear type. Despite its widespread occurrence, observations of bycatch are rare, and scientific data on marine mammal bycatch are limited. Difficulties result in developing models that accurately depict the interactions. This study focuses on developing methodology to combine disparate data sources, specifically data from fishery observer programs and interviews of fishermen, to better understand these interactions and to identify effective mitigation measures. As a case study, this research investigates …

Ion Sequestration Particles For Naval Anticorrosion Coatings, Zachary Z. Zguris

Doctoral Dissertations

Corrosion is the electrochemical process of a metal returning to its lower energy state, the metal oxide. The cost of corrosion is difficult to estimate. One area particularly susceptible to corrosion problems with high maintenance costs is that of the 20,000 tanks existent in the US Naval Fleet. The Navy is sponsoring the development of novel coatings and additives that can be used to decrease the rising corrosion related costs.

This dissertation describes in detail the synthesis of Ion Sequestration Particles (ISP) that when added to the standard MIL-DTL-24441 or potentially another coating system act to enhance the anticorrosion properties …

Investigation And Characterization Of Size Effects In Microforming Processes, Sunal Ahmet Parasiz

Doctoral Dissertations

The products of miniaturization, such as mobile phones, personal digital assistants, computers and other electronic devices have become an indispensable part of our daily lives. Nowadays, more and more industrial products including some medical and electromechanical products contain micro scale metal parts such as connector pins, resistor caps, screws, contact springs and chip lead frames. Miniaturization brings the challenge of realizing the production of these microscale metals parts. Microforming, due to its well known advantages of high production rates, excellent material utilization, and low costs, is a promising manufacturing method compared to the alternative processes in this field. However, well-established …

Uncertainty Analysis And Sensitivity Analysis For Multidisciplinary Systems Design, Jia Guo

Doctoral Dissertations

"The objective of this research is to quantify the impact of both aleatory and epistemic uncertainties on performances of multidisciplinary systems. Aleatory uncertainty comes from the inherent uncertain nature and epistemic uncertainty comes from the lack of knowledge. Although intensive research has been conducted on aleatory uncertainty, few studies on epistemic uncertainty have been reported. In this work, the two types of uncertainty are analyzed. Aleatory uncertainty is modeled by probability distributions while epistemic uncertainty is modeled by intervals. Probabilistic analysis (PA) and interval analysis (IA) are integrated to capture the effect of the two types of uncertainty. The First …

Characterization And Synthesis Of Nanoscale Materials, Jinfeng Wang

Doctoral Dissertations

"This dissertation focuses on the systematic study of techniques for characterization and synthesis of nanoscale materials. We have achieved several goals. Firstly, high number density uniform zinc oxide nanostructure growth has been achieved using thermal evaporation, through control of experimental parameters that include source material temperature, substrate temperature, substrate material, gas flow rate, and choice of catalyst. Aligned zinc oxide nanowires, randomly oriented zinc oxide nanowires, zinc oxide container-shaped structures, and zinc oxide nanobelts have been synthesized with high yield. Secondly, using a one parameter family of lattice fringe geometry curves, we show how to examine the epitaxial relationship between …

Design And Evaluation Of A Virtual Reality Training System For New Underground Rockbolters, David Nutakor

Doctoral Dissertations

"The need for development of better training techniques for underground rock bolters is signified by the fact that a large number of experienced miners (Baby Boomers) will be retiring soon. This means that there will be very little interface time between the new miners and the experienced miners, which could have been used for training the new inexperienced miners. A new generation of workers (Nexters), who have grown up with computers and video games will replace the Baby Boomers, and the most efficient way to introduce them to the safety and health issues of the mining industry is to use …

Energy Efficient Clustering And Secure Data Aggregation In Wireless Sensor Networks, Julia Albath

Doctoral Dissertations

"Communication consumes the majority of a wireless sensor network's limited energy. There are several ways to reduce the communication cost. Two approaches used in this work are clustering and in-network aggregation. The choice of a cluster head within each cluster is important because cluster heads use additional energy for their responsibilities and that burden needs to be carefully distributed. We introduce the energy constrained minimum dominating set (ECDS) to model the problem of optimally choosing cluster heads in the presence of energy constraints. We show its applicability to sensor networks and give an approximation algorithm of O(log n) for solving …

Energy Efficient Wireless Sensor Network Protocols For Monitoring And Prognostics Of Large Scale Systems, James W. Fonda

Doctoral Dissertations

"In this work, energy-efficient protocols for wireless sensor networks (WSN) with applications to prognostics are investigated. Both analytical methods and verification are shown for the proposed methods via either hardware experiments or simulation. This work is presented in five papers. Energy-efficiency methods for WSN include distributed algorithms for i) optimal routing, ii) adaptive scheduling, iii) adaptive transmission power and data-rate control"--Abstract, page iv.

Integrated Process Planning For A Hybrid Manufacturing System, Lan Ren

Doctoral Dissertations

"A hybrid manufacturing system integrated CNC machining and laser-aided layered deposition and achieves the benefits of both processes. In this dissertation, an integrated process planning framework which aims to automate the hybrid manufacturing process is investigated. Critical components of the process planning, including 3D spatial decomposition of the CAD model, improvement of the toolpath generation pattern, repairing strategies using a hybrid manufacturing system, etc., are discussed"--Abstract, page iv.

Modeling And Rendering For Development Of A Virtual Bone Surgery System, Qiang Niu

Doctoral Dissertations

"A virtual bone surgery system is developed to provide the potential of a realistic, safe, and controllable environment for surgical education. It can be used for training in orthopedic surgery, as well as for planning and rehearsal of bone surgery procedures...Using the developed system, the user can perform virtual bone surgery by simultaneously "seeing" bone material removal through a graphic display device, "feeling" the force via a haptic deice, and "hearing" the sound of tool-bone interaction"--Abstract, page iii.

System And Ic Level Analysis Of Electrostatic Discharge (Esd) And Electrical Fast Transient (Eft) Immunity And Associated Coupling Mechanisms, Jayong Koo

Doctoral Dissertations

"The exposure of electronic circuits to lightning, electrostatic discharge (ESD), electrical fast transients (EFT) or sine wave signals can reveal RF immunity problems. Typical problems include temporary malfunctions or permanent damage of integrated circuits (ICs). In an effort to reproduce those disturbances, a series of electromagnetic compatibility standards has been developed. However, a complete understanding of the root cause of the immunity problems has yet to be established. This dissertation discusses immunity problems in three papers, starting at the system level, via the coupling path into the IC"--Abstract, page iv.

Densification, Microstructure, And Mechanical Properties Of Zirconium Diboride Based Ultra-High Temperature Ceramics, Sumin Zhu

Doctoral Dissertations

"The first part of this dissertation was aimed at studying the densification of ZrB₂ ceramics by pressureless sintering techniques. Various processes have been applied to coat ZrB₂ powders with polymer precursors, which were used to produce C after charring. After sintering at 1900⁰C, relative density increased of ~70% for uncoated ZrB₂ to >99% for ZrB₂ coated with at least 1.0 wt% C. Thermodynamic analysis suggested that C reacted with and removed oxide impurities (ZrO₂ and B₂O₃) that were present on the ZrB₂ particle surfaces, which promoted densification by minimizing grain coarsening"--Abstract, page iv.

Formation And Removal Of Pesticides And Pesticide Transformation Products During Water Treatment, Evelyn F. Chamberlain

Doctoral Dissertations

"A comprehensive suite of over 60 pesticides (herbicides, insecticides, and fungicides) representing a variety of classes at environmentally relevant concentrations (low µg/L) were screened for reactivity under typical drinking water conditions and dosages. The most common oxidants/transformation agents in water treatment systems were examined for reactivity including free and combined chlorine, chlorine dioxide, permanganate, ozone, hydrogen peroxide, ultraviolet radiation, and high pH (alkaline hydrolysis). Due to the broad nature of the study, pesticide compounds were analyzed as multiple mixes broken into two groups based on analytical methods, those analyzed by GC/ECD and those by LC/MS. Combinations of reactive disinfectant/oxidant and …

Mechanics Of Dump Truck Vibrations In High-Impact Shovel Loading Operations, Nassib Aouad

Doctoral Dissertations

"The deployment of large machinery for low cost, bulk surface mine production operations has resulted in high-impact shovel loading operations (HISLO). In extreme cases, shovels load large dump trucks with 100-ton (or more) passes generating high-impact forces under gravity. HISLO generates high-frequency shockwaves that cause severe truck vibrations exposing operators to whole body vibrations (WBV). This WBV levels may exceed the recommended International Standards Organization (ISO) limits resulting in longterm lower-back disorders and other health problems. There is a need for fundamental and applied research to determine HISLO vibration levels for heavy mining machinery, their comparisons to ISO 2631 limits …

Design And Optimization Of Abrasive Slurry Feed System, Control Circuit And Jet Drilling Tool For Mining Applications,, Pradeep Nambiath

Doctoral Dissertations

"This dissertation focused on an investigation of small diameter hole drilling using abrasive slurry jet (ASJ) technology. The existing ASJ feed systems were reviewed and found inadequate to satisfy the requirements of an ASJ drill. A novel feed system was designed which improved on existing systems by resolving problems with the inability to perform stop/start operations and ensure precise metering of abrasive feed. This system met standards of consistency and evenness of feed required for machining aircraft component parts for Air Force Research Laboratory (AFRL). Theoretical and experimental analysis of the power of an ASJ stream yielded valuable design information …

Over The Seas, Over The Generations : Narratives Of Multigenerational Korean Women In Japan And Japanese American Women In The United States, Kayoko Aoki

Doctoral Dissertations

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Imagining And Creating New Possibilities For Self And Society : Narratives Of Nepalese University Students Gone Abroad, Kristine Nelson

Doctoral Dissertations

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Enabling Wind Turbine Generators To Participate In Power Grid Frequency Regulation For Enhanced Stability, Hongtao Ma

Doctoral Dissertations

"This dissertation focuses on wind farm frequency regulation capability to maintain the grid frequency stability. Wind plant power controllers are designed and tested for participation in grid frequency restoration. The small signal stability on sub-optimal operating points is analyzed and a de-loaded operating point is proposed.

In the first paper, a new frequency regulation scheme is developed for the wind turbine/generator/converter trio that will provide the capability to participate in restoring frequency in a way similar to the droop response of conventional generators. Output active power adjustment can be realized by both converter and pitch angle control in addition to …

Unsteady Flow And Heat Transfer In Periodic Complex Geometries For The Transitional Flow Regime, Li-Kwen Chen

Doctoral Dissertations

"Diesel engines are facing significant challenges with upcoming changes in emissions standards. In general, meeting the increased emission standards will require a larger fraction of the engine heat rejection to occur in the vehicle cooling system. For certain applications, the surface geometry must also be such that it resists particulate fouling, precluding common interrupted surfaces such as louvered fins. Although acceptable continuous surface geometries such as bumped fin geometries are in use, the impacts of changing the parameters of this geometry are unknown. This study investigates the transport characteristics of bumped fins in the transitional flow regime using unsteady multi-dimensional …

Multiple-Input Multiple-Output Wireless Communications With Imperfect Channel Knowledge, Christopher Potter

Doctoral Dissertations

"In the first work a recurrent neural network (RNN) is employed for MIMO channel prediction. A novel PSO-EA-DEPSO off-line training algorithm is presented and is shown to outperform PSO, PSO-EA, and DEPSO. This predictor is shown to be robust to varying channel scenarios. New expressions for the received SNR, array gain, average probability of error, and diversity gain are derived. Next, a new expression for the outage capacity of a MIMO system with no CSI at the transmitter and an estimate at the receiver is presented. Since the outage capacity is a function of the first and second moments of …

Thin Film Techniques For The Fabrication Of Nano-Scale High Energy Density Capacitors, James N. Reck

Doctoral Dissertations

Dielectric thin films of either TiO₂ or BaTiO₃ were sputtered in O₂/Ar plasmas on Si wafers to thicknesses ranging from approximately 25 to 200 nm with patterned Ni or Pt electrodes sputtered in Ar plasmas at thicknesses from about 20 to 250 nm to form nano-capacitors. Statistical design of experiments (DOE) was used to determine the effects of the deposition power, plasma composition, and deposition temperature on the measured electrical properties of the nano-capacitors. Additional tests to determine the effects of the dielectric and electrode thickness on the measured dielectric responses of the devices were also undertaken. Characterization was performed …

Physical Modeling Of Railroad Ballast Using The Parallel Gradation Scaling Technique Within The Cyclical Triaxial Framework, Adam F. Sevi

Doctoral Dissertations

"Due to the difficulties involved with testing large particle granular materials such as rockfill and railroad ballast, several methods of testing scaled down model specimens have been introduced. Of these techniques, the parallel gradation model has been found to be most useful. The parallel gradation model states that a smaller grainsize distribution model granular material, of the same composition as the prototype material, can be used in triaxial testing at a scaled down grainsize, if the model materials grainsize is exactly parallel to the prototype material. Therefore, a model granular material composed of a smaller, but parallel, grainsize distribution can …

Three-Dimensional Laminar And Turbulent Convection In Separated Flow, Magesh Thiruvengadam

Doctoral Dissertations

"Three-dimensional laminar and turbulent separated flow and heat transfer in plane symmetric sudden expansion and plane backward facing step is examined in this dissertation. In Papers I, II, and III, simulations of 3-D laminar forced convection in plane symmetric expansion is studied...In Paper IV, 3-D turbulent flow measurements using Laser Doppler Velocimeter are made in a backward facing step flow and the three velocity components and the Reynolds stresses are measured in the separated and redeveloping flow region...In Paper V, the 2-D behavior of a thin film that is shear driven by turbulent air flow is simulated"--Abstract, page iv.

Speculation And Hedging With Virtuals, Prasenjit Shil

Doctoral Dissertations

"Virtual bid" and "Virtual offer" are purely financial products offered in certain electricity markets. Theoretically, virtual bids and offers can change the electricity price as the bids and offers are stacked along with the demand and supply, respectively. This dissertation discusses how virtuals can be used to hedge and speculate in the electricity market. A statistical simulation model is developed based on the day-ahead (DA) demand and real time (RT) load data from Midwest Independent Transmission System Operator's (MISO) footprint and DA and RT price observed at Cinergy hub. The simulation models are intended to mimic the load and price …