Engineering Commons^™

An Effective Approach To Nonparametric Quickest Detection And Its Decentralized Realization, Dayu Yang

Doctoral Dissertations

This dissertation focuses on the study of nonparametric quickest detection and its decentralized implementation in a distributed environment. Quickest detection schemes are geared toward detecting a change in the state of a data stream or a real-time process. Classical quickest detection schemes invariably assume knowledge of the pre-change and post-change distributions that may not be available in many applications. A distribution free nonparametric quickest detection procedure is presented based on a novel distance measure, referred to as the Q-Q distance calculated from the Quantile-Quantile plot. Theoretical analysis of the distance measure and detection procedure is presented to justify the proposed …

Microfluidic Manipulation By Ac Electrothermal Effect, Meng Lian

Doctoral Dissertations

AC Electrokinetics (ACEK) has attracted much research interest for microfluidic manipulation for the last few years. It shows great potential for functions such as micropumping, mixing and concentrating particles. Most of current ACEK research focuses on AC electroosmosis (ACEO), which is limited to solutions with conductivity less than 0.02 S/m, excluding most biofluidic applications. To solve for this problem, this dissertation seeks to apply AC electrothermal (ACET) effect to manipulate conductive fluids and particles within, and it is among the first demonstration of ACET devices, a particle trap and an ACET micropump. The experiments used fluids at a conductivity of …

A Novel Technique For Ctis Image-Reconstruction, Mitchel Dewayne Horton

Doctoral Dissertations

Computed tomography imaging spectrometer (CTIS) technology is introduced and its use is discussed. An iterative method is presented for CTIS image-reconstruction in the presence of both photon noise in the image and post-detection Gaussian system noise. The new algorithm assumes the transfer matrix of the system has a particular structure. Error analysis, performance evaluation, and parallelization of the algorithm is done. Complexity analysis is performed for the proof of concept code developed. Future work is discussed relating to potential improvements to the algorithm.

An intuitive explanation for the success of the new algorithm is that it reformulates the image reconstruction …

Polymeric Microsensors For Intraoperative Contact Pressure Measurement, Emily R. Pritchard

Doctoral Dissertations

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays …

The Development Of A Parameterized Scatter Removal Algorithm For Nuclear Materials Identification System Imaging, Brandon Robert Grogan

Doctoral Dissertations

This dissertation presents a novel method for removing scattering effects from Nuclear Materials Identification System (NMIS) imaging. The NMIS uses fast neutron radiography to generate images of the internal structure of objects non-intrusively. If the correct attenuation through the object is measured, the positions and macroscopic cross-sections of features inside the object can be determined. The cross sections can then be used to identify the materials and a 3D map of the interior of the object can be reconstructed. Unfortunately, the measured attenuation values are always too low because scattered neutrons contribute to the unattenuated neutron signal. Previous efforts to …

Improving Ozone Sip Modeling In Complex Terrain At A Fine Grid Resolution, Yunhee Kim

Doctoral Dissertations

Meteorological variables such as temperature, wind speed, wind directions, and Planetary Boundary Layer (PBL) heights have critical implications for air quality simulations. Sensitivity simulations with five different PBL schemes associated with three different Land Surface Models (LSMs) were conducted to examine the impact of meteorological variables on the predicted ozone concentrations using the Community Multiscale Air Quality (CMAQ) version 4.5 with local perspective. Additionally, the nudging analysis for winds was adopted with three different coefficients to improve the wind fields in the complex terrain at 4-km grid resolution. The simulations focused on complex terrain having valley and mountain areas for …

Theoretical Models For Wall Injected Duct Flows, Tony Saad

Doctoral Dissertations

This dissertation is concerned with the mathematical modeling of the flow in a porous cylinder with a focus on applications to solid rocket motors. After discussing the historical development and major contributions to the understanding of wall injected flows, we present an inviscid rotational model for solid and hybrid rockets with arbitrary headwall injection. Then, we address the problem of pressure integration and find that for a given divergence free velocity field, unless the vorticity transport equation is identically satisfied, one cannot find an analytic expression for the pressure by direct integration of the Navier-Stokes equations. This is followed by …

Investigation Of The Processing, Structure And Properties Of Poly(Phenylene Sulfide) (Pps) Melt Spun Fibers, Prabhakar Gulgunje

Doctoral Dissertations

Numerous publications are available on the structure and properties correlation of fibers spun from polymers with flexible chains such as polyethylene terephthalate (PET), nylon, polypropylene. Also considerable amount of work is reported in fibers spun from rigid rod polymers like poly(p-phenylene terephthalamide) due to their value in high performance fibers category. However, very limited literature is available on the structure-properties relationship in fibers manufactured from poly(phenylene sulfide) (PPS), a high performance polymer which possesses chain flexibility between above two classes of polymers. A few researchers have studied crystallization kinetics and the fibers by extruding the polymer using capillary rheometers. However, …

Merging Data Sources To Predict Remaining Useful Life – An Automated Method To Identify Prognostic Parameters, Jamie Baalis Coble

Doctoral Dissertations

The ultimate goal of most prognostic systems is accurate prediction of the remaining useful life (RUL) of individual systems or components based on their use and performance. This class of prognostic algorithms is termed Degradation-Based, or Type III Prognostics. As equipment degrades, measured parameters of the system tend to change; these sensed measurements, or appropriate transformations thereof, may be used to characterize degradation. Traditionally, individual-based prognostic methods use a measure of degradation to make RUL estimates. Degradation measures may include sensed measurements, such as temperature or vibration level, or inferred measurements, such as model residuals or physics-based model predictions. Often, …

Monotonic And Cyclic Compression Behavior Of Bulk Metallic Glasses, Matthew Webster Freels

Doctoral Dissertations

The cyclic-compression behavior of a Cu45Zr45Al5Ag5 bulk metallic glass (BMG) was investigated in order to elucidate the damage initiation and growth mechanisms. The present Cu45Zr45Al5Ag5 BMG was found to have the highest fatigue-endurance limit for BMGs reported to date. Fracture under cyclic compression occurred in a pure shear mode. In addition to many shear bands and cracks, areas of “chipping” were commonly found on the outside surfaces of the fatigue specimens. Crack growth rates were found decrease with cycles.

The effects of the as-cast specimen size, cooling rate, and the free volume content on the monotonic and cyclic compression behavior …

An Adaptive Nonparametric Modeling Technique For Expanded Condition Monitoring Of Processes, Matthew John Humberstone

Doctoral Dissertations

New reactor designs and the license extensions of the current reactors has created new condition monitoring challenges. A major challenge is the creation of a data-based model for a reactor that has never been built or operated and has no historical data. This is the motivation behind the creation of a hybrid modeling technique based on first principle models that adapts to include operating reactor data as it becomes available.

An Adaptive Non-Parametric Model (ANPM) was developed for adaptive monitoring of small to medium size reactors (SMR) but would be applicable to all designs. Ideally, an adaptive model should have …

A New Lean Model: Improving Race Team Performance Through Team-Driver Communication Efficacy, Joseph Ruric Stainback Iv

Doctoral Dissertations

In some organizational settings and in the field of competitive automobile racing, certain situations and rules place an emphasis on and sometimes escalate the need for effective team communications. This dissertation hypothesizes that effective and dense communications contributes directly to team performance. Supported by organizational behavioral and lean six sigma theory, communications is declared a form of waste within the context of Industrial Engineering subject to data collection, measurements, and real-time, value-added metrics. Measuring and reporting trends in communications provides a basis for a new and unique model called a Communications Productivity Model (CPM) with an associated Communications Density Report …

Molecular Simulations Of Adsorption And Diffusion In Metal-Organic Frameworks (Mofs), Ruichang Xiong

Doctoral Dissertations

Metal-organic frameworks (MOFs) are a new class of nanoporous materials that have received great interest since they were first synthesized in the late 1990s. Practical applications of MOFs are continuously being discovered as a better understanding of the properties of materials adsorbed within the nanopores of MOFs emerges. One such potential application is as a component of an explosive-sensing system. Another potential application is for hydrogen storage.

This work is focused on tailoring MOFs to adsorb/desorb the explosive, RDX. Classical grand canonical Monte Carlo (GCMC) and molecular dynamic (MD) simulations have been performed to calculate adsorption isotherms and self-diffusivities of …

Kernel-Based Data Mining Approach With Variable Selection For Nonlinear High-Dimensional Data, Seung Hyun Baek

Doctoral Dissertations

In statistical data mining research, datasets often have nonlinearity and high-dimensionality. It has become difficult to analyze such datasets in a comprehensive manner using traditional statistical methodologies. Kernel-based data mining is one of the most effective statistical methodologies to investigate a variety of problems in areas including pattern recognition, machine learning, bioinformatics, chemometrics, and statistics. In particular, statistically-sophisticated procedures that emphasize the reliability of results and computational efficiency are required for the analysis of high-dimensional data. In this dissertation, first, a novel wrapper method called SVM-ICOMP-RFE based on hybridized support vector machine (SVM) and recursive feature elimination (RFE) with information-theoretic …

Flow-Based Adaptive Split Signal Control, Airton G. Kohls

Doctoral Dissertations

Over the last 35 years many adaptive traffic signal control systems have been developed presenting alternative strategies to improve traffic signal operations. However, less than 1% of all traffic signals in the United States are controlled by adaptive systems today. The extensive infrastructure necessary including reliable communication and complex calibration leads to a time consuming and costly process. In addition, the most recent National Traffic Signal Report Card indicated an overall grade of D for the nation’s traffic signal control and operations. Recent economic adversity adds to the already difficult task of proactively managing aged signal timing plans.

Therefore, in …

Long-Term Acid Deposition Effects On Soil And Water Chemistry In The Noland Divide Watershed, Great Smoky Mountains National Park, Usa, Meijun Cai

Doctoral Dissertations

Impacts of long-term acid deposition on soil and water chemistry are of particular concern in the Great Smoky Mountains National Park (GRSM), receiving some of the highest acid deposition rates in the eastern United States and limited by inadequate acid buffering capacity. In the GRSM, the Noland Divide watershed (NDW) has been monitored since 1991 for water chemistries of precipitation, throughfall, soil, and stream. The impacts of long-term acidic deposition on stream water quality in the NDW were investigated through: 1) development of an ion input-output budget; 2) analysis of trends and seasonal patterns for major ions; 3) comparison of …

A High-Temperature, High-Voltage Soi Gate Driver Integrated Circuit With High Drive Current For Silicon Carbide Power Switches, Mohammad Aminul Huque

Doctoral Dissertations

High-temperature integrated circuit (IC) design is one of the new frontiers in microelectronics that can significantly improve the performance of the electrical systems in extreme environment applications, including automotive, aerospace, well-logging, geothermal, and nuclear. Power modules (DC-DC converters, inverters, etc.) are key components in these electrical systems. Power-to-volume and power-to-weight ratios of these modules can be significantly improved by employing silicon carbide (SiC) based power switches which are capable of operating at much higher temperature than silicon (Si) and gallium arsenide (GaAs) based conventional devices. For successful realization of such high-temperature power electronic circuits, associated control electronics also need to …

Multi-Scale Simulation Of Linear, Short-Chain Polyethylene Liquids Under Flow Conditions, Jun Mo Kim

Doctoral Dissertations

The rheological and structural properties of polymeric liquids cannot be condensed within a single numerical model. They should be described within hierarchical, multi-level numerical models in which each sub-model is responsible for different time and length scales; atomistic, mesoscopic, and continuum. In this study, the rheological and structural properties of linear, short-chain polyethylene liquids were investigated from the classical atomistic level to the mesoscopic and continuum levels of description. At the atomistic level of description, nonequilibrium molecular dynamics (NEMD) simulations of linear, short-chain polyethylene liquids spanning from C16H24 to C128H256 were performed to advance our knowledge of fundamental characteristic of …

Anomaly Detection In Unknown Environments Using Wireless Sensor Networks, Yuanyuan Li

Doctoral Dissertations

This dissertation addresses the problem of distributed anomaly detection in Wireless Sensor Networks (WSN). A challenge of designing such systems is that the sensor nodes are battery powered, often have different capabilities and generally operate in dynamic environments. Programming such sensor nodes at a large scale can be a tedious job if the system is not carefully designed. Data modeling in distributed systems is important for determining the normal operation mode of the system. Being able to model the expected sensor signatures for typical operations greatly simplifies the human designer’s job by enabling the system to autonomously characterize the expected …

Analysis Of Conjugated Polymer Nanotubules Formed By Template Wetting Nanofabrication, Steven D. Bearden Jr.

Doctoral Dissertations

Semiconducting and optoelectric conjugated polymers have potential in micro and nano-electronic applications. Their widely tunable physical conformations and orientations make these polymers ideal material for engineering small scale devices. The polymers have been incorporated into several electronic devices including light-emitting diodes, solar cells, and field-effect transistors. Widespread adoption of these materials will not be a reality until the issues of poor device performance, short lifespans, and device degradation are resolved.

Nanostructures have been demonstrated to have improvements in molecular ordering and electronic transport. In the work presented here, tubular nanostructures of conjugated polymers fabricated by the template wetting nanofabrication process …

Experimental Investigation Of Flow And Heat Transfer Characteristics Of R -134a In Microchannels, Abdullahel Bari

Doctoral Dissertations

The purpose of this study was to investigate the flow and heat transfer characteristics of liquid refrigerant R-134a in rectangular microchannels. The research concentrated mostly upon single-phase experiments with limited investigation of boiling phenomenon in microchannels. Tests were performed using rectangular microchannels with hydraulic diameters ranging from 112 μm to 210 μm and aspect ratios varying approximately from 1.0 to 1.5. The Reynolds number in the experiments ranged from 1,200 to 13,000 although most data were collected in the transition and turbulent flow regimes.

The experimental data for friction factor measurement had a similar trend as predicted by macroscale theory …

Development Of A Geopolymer-Based Cementitious Coating For The Rehabilitation Of Buried Concrete Infrastructure, Carlos Montes

Doctoral Dissertations

The current research project was devoted to the incorporation of geopolymers as a new material for Trenchless projects, taking advantage of their properties in a field in which they had not been used before, providing a substantial help to municipalities to meet their rehabilitation needs. Trenchless Technologies are a family of methods, materials and equipment capable of being used for the installation of new or replacement or rehabilitation of existing underground infrastructure with minimal disruption to surface traffic, business, and other activities.

The dissertation research work described herein is divided into six primary objectives: (1) the evaluation of geopolymer as …

Dna Microarray Image Segmentation Using Active Contours Without Edges Method, Shenghua Ni

Doctoral Dissertations

The goal of this dissertation is to build a better segmentation method for DNA microarray image processing. Segmentation is a partitioning process used to separate a spot area from a non-spot area in DNA microarrays. It directly affects the accuracy of gene expression analysis in the data mining process that follows. A number of DNA microarray segmentation methods have been proposed in the area, but even modern segmentation methods seem to have accuracy problems. In this dissertation, I will present a segmentation method based on the Active Contours Without Edges (ACWE) algorithm and apply it to two types of DNA …

Understanding Corrosion Of Ni₃(Si,Nb) Alloys In Hot Sulfuric Acid, Jen-Hsien Hsu

Doctoral Dissertations

"The Sulfur-Iodine thermochemical cycle has been proposed as a method for producing large quantities of hydrogen gas from water. However, the extreme operating environments involved limit the possible materials for construction.

Through proper heat treatment and composition control, the modified patented Ni₃(Si,Nb) alloy keeps high temperature strength to greater than 750⁰C and can be deformed by cold rolling more than 50% using multiple passes and intermediate anneals. The corrosion resistance is reproducible and maintains less than 5 mpy for a broad range of boiling sulfuric acid concentrations, including 70 wt%.

In the boiling 70 wt% sulfuric acid corrosion tests, kinetic …

Ceramic Dielectrics For High Energy Density Capacity Application, Sheng Chao

Doctoral Dissertations

"The objective of this dissertation is to investigate the relationship between the processing parameters, microstructural development, defect chemistry and electrical properties of titanium oxide (TiO₂) dielectrics for high energy density capacitor applications. The effects of aliovalent dopants on the dielectric properties of TiO₂ ceramics were investigated, aiming to further improve the desired dielectric properties especially at elevated temperatures (up to 200°C). Due to the segregation of acceptor type impurities in the starting powders, space charge polarization took place in TiO₂ ceramics with relative large grain size (>̲500nm), leading to high dielectric loss and low energy storage efficiency. Increased ratio …

Sensor Data-Based Decision Making, Ahmet Soylemezoglu

Doctoral Dissertations

"Increasing globalization and growing industrial system complexity has amplified the interest in the use of information provided by sensors as a means of improving overall manufacturing system performance and maintainability. However, utilization of sensors can only be effective if the real-time data can be integrated into the necessary business processes, such as production planning, scheduling and execution systems. This integration requires the development of intelligent decision making models that can effectively process the sensor data into information and suggest appropriate actions. To be able to improve the performance of a system, the health of the system also needs to be …

Advanced Dynamic Response Improvement Methods For Dc-Dc Power Electronic Converters, Lisheng Shi

Doctoral Dissertations

"Dc-dc power electronic converters supplying electric power to digital processors, data centers, and telecommunication systems are required to exhibit a fast dynamic response in response to their instantaneous electric load variations. This requirement is becoming more and more stringent as the operating voltage of such loads is continuously reducing. This voltage level reduction has reached a point where conventional control approaches can barely meet the dynamic response demanded by such loads. In order to overcome this issue, several approaches focusing on the dynamic response improvement for dc-dc converters have been proposed in the literature. Unfortunately, most of them have at …

The Functionalization Of Single Wall Carbon Nanotubes For Bioapplications, Pu Zhang

Doctoral Dissertations

"In the past few years, the functionalization of carbon nanotubes has received considerable attention due to their extraordinary mechanical, electrical, optical and thermal properties. Using single wall carbon nanotube as a platform in bioanalytical and biomedical applications has also been extensively studied. This dissertation consists of four papers. In the first paper, various methods to functionalize single wall carbon nanotubes with immobilized enzyme for bioanalytical application were investigated. It was found that the covalent functionalization method was not an ideal methodology for enzyme addition neither in terms of enzyme loading amount nor activity retention compared to other methods. Use of …

Integrated, Multi-Attribute Decision Support System For The Evaluation Of Underground Utility Construction Methods, John C. Matthews

Doctoral Dissertations

The dissertation research work described herein is comprised of three primary objectives: (1) the development of a rehabilitation method selection software (TAG-R) for the National Association of Sewer Service Companies (NASSCO) and its subsequent validation and combination with TAG (a sister decision support system (DSS) software developed by the author in an earlier work); (2) the development of a social cost calculator (SCC) and its validation; and (3) the development of a proposed framework for multi-segment optimization for construction methods selection using the tools developed in the first two objectives as well as additional project related data.

The selection of …

Low-Thrust Control Of Orbital Elements, Nathan Harl

Doctoral Dissertations

"This dissertation presents a method for controlling the orbital elements of a spacecraft using continuous low-thrust systems. The method involves the use of a general performance index, which is designed to minimize the difference between the instantaneous orbital elements of a spacecraft and some desired set of orbital elements. Due to the generality of the controller design, the resultant controller can be applied to a wide variety of scenarios about various bodies in space. To minimize the designed performance index, a shooting method and a Sequential Quadratic Programming algorithm are utilized and compared.

The primary application of the general controller …