Digital Commons Network^™

Cerebral Spasticity Modeled As Disorded Equilibrium Point Control, Darnell Simon

Dissertations

Spasticity is a highly complex phenomenon, which has not been defined in precise and quantifiable terms. Although the muscle stretch reflex is thought to play an important role in spasticity generation, the pathophysiologic basis of spasticity is not completely understood. A valid measure of spasticity is one that is chosen within the context of a theory describing the physiological mechanisms underlying the control of posture and movement in healthy individuals and possible impairments of these mechanisms leading to motor disorders. This research’s goal was to determine the role of stretch reflex threshold in the regulation of impaired motor control through …

Target Localization In Passive And Active Systems : Performance Bonds, Vlad Mihai Chiriac

Dissertations

The main goal of this dissertation is to improve the understanding and to develop ways to predict the performance of localization techniques as a function of signal-to-noise ratio (SNR) and of system parameters. To this end, lower bounds on the maximum likelihood estimator (MLE) performance are studied. The Cramer-Rao lower bound (CRLB) for coherent passive localization of a near-field source is derived. It is shown through the Cramer-Rao bound that, the coherent localization systems can provide high accuracies in localization, to the order of carrier frequency of the observed signal. High accuracies come to a price of having a highly …

High Rate Space Time Code With Linear Decoding Complexity For Multiple Transmitting Antennas, Amir Laufer

Dissertations

The multipath nature of the wireless channel, results in a superposition of the signals of each path at the receiver. This can lead to either constructive or destructive interference. Strong destructive interference is frequently referred to as deep fade and may result in temporary failure of communication due to the severe drop in the channel's signal-to-noise ratio (SNR). To avoid this situation, signal diversity might be introduced. When having more than one antenna at the transmitter and / or receiver, forming a Multiple-Input Multiple-Output (MIMO) channel, spatial diversity can be employed to overcome the fading problem. Space time block codes …

Influence Of Defects And Impurities On Solar Cell Performance, Vinay Budhraja

Dissertations

Multicrystalline silicon (mc-Si) solar cells exhibit high impurity content and higher density of crystal defects such as grain boundaries, dislocations, stacking faults and impurity precipitates. Even though the effect of dislocations on mc-Si solar cell performance has been studied, a severe lack of understanding of the quantitative effects of dislocations on cell parameters still exists. Some correlation has been reported under the assumption of a uniform distribution of dislocation density and a negligible effect of front and back surface recombination velocity. This assumption can cause a significant error as the current mc-Si technology provides good surface passivation by SiN:H and …

Wireless Sensor Network For Health Monitoring, Jin Soo Choi

Dissertations

Wireless Sensor Network (WSN) is becoming a significant enabling technology for a wide variety of applications. Recent advances in WSN have facilitated the realization of pervasive health monitoring for both homecare and hospital environments. Current technological advances in sensors, power-efficient integrated circuits, and wireless communication have allowed the development of miniature, lightweight, low-cost, and smart physiological sensor nodes. These nodes are capable of sensing, processing, and communicating one or more vital signs. Furthermore, they can be used in wireless personal area networks (WPANs) or wireless body sensor networks (WBSNs) for health monitoring. Many studies were performed and/or are under way …

Using An Ontology To Improve The Web Search Experience, Tian Tian

Dissertations

The search terms that a user passes to a search engine are often ambiguous, referring to homonyms. The results in these cases are a mixture of links to documents that contain different meanings of the search terms. Current search engines provide suggested query completions in a dropdown list. However, such lists are not well organized, mixing completions for different meanings. In addition, the suggested search phrases are not discriminating enough. Moreover, current search engines often return an unexpected number of results. Zero hits are naturally undesirable, while too many hits are likely to be overwhelming and of low precision.

This …

Consequences Of Stochastic Mrna Synthesis In A Gene Regulatory Pathway, Khyati Shah

Dissertations

Gene expression is a stochastic process, with elements of randomness present in both transcription and translation. This stochasticity results in cell-to-cell variation in the amounts of gene products, mRNAs and proteins, and is observed in organisms ranging from bacteria and yeast to higher eukaryotes. Randomness in the activation and inactivation of a gene is the preliminary cause of this variation. At the level of proteins, these variations are buffered compared to levels of mRNA, due to the longer lifespan of proteins. Nevertheless, there is substantial variation observed at the level of proteins, resulting in phenotypic diversity among genetically identical cells. …

Terahertz Wireless Communication, Ke Su

Dissertations

The goal of this thesis is to explore Terahertz (THz) wireless communication technology. More specifically the objective is to develop and characterize several THz communication systems and study the effect of atmosphere propagation through fog droplets and dust particles on THz communications.

For demonstration, a THz continuous wave (CW) photomixing system is designed. Terahertz signals are phase encoded with both analog ramp signals and pseudorandom binary data, transmitted over a short distance, and detected. The limitation of transmission bandwidth, low single to noise ratio, vibration effects are also analyzed. In order to study and compare propagation features of THz links …

Design And Implementation Of A Cyberinfrastructure For Rna Motif Search, Prediction And Analysis, Dongrong Wen

Dissertations

RNA secondary and tertiary structure motifs play important roles in cells. However, very few web servers are available for RNA motif search and prediction. In this dissertation, a cyberinfrastructure, named RNAcyber, capable of performing RNA motif search and prediction, is proposed, designed and implemented.

The first component of RNAcyber is a web-based search engine, named RmotifDB. This web-based tool integrates an RNA secondary structure comparison algorithm with the secondary structure motifs stored in the Rfam database. With a user-friendly interface, RmotifDB provides the ability to search for ncRNA structure motifs in both structural and sequential ways. The second component of …

Micromechanical Study Of Two-Phase Flow During Air Sparging, Shengyan Gao

Dissertations

Air sparging (AS) is an in-situ soil/groundwater remediation technology, which involves the injection of pressurized air/oxygen through an air sparging well below the region of contamination. The efficiency of the in-situ sparging system is mainly controlled by the extent of contact between injected air and contaminated soil and pore fluid. Hence, characterizing the mechanisms governing movement of air through saturated porous media is therefore critical to the design of an effective cleanup treatment. However, in spite of the success of air sparging as a remediation technique for the clean-up of contaminated soils, to date, the fundamental mechanisms or the physics …

Development Of X-Ray Holography Methods For Structure Determination : Application Of High Speed Detectors And Novel Numerical Methods, Yuhao Wang

Dissertations

Holographic methods show much promise to enable direct determination of atomic structure with minimal assumptions and approximations. The approach can, in principle, provide three dimensional information on atomic positions. However, significant developments in experimental techniques, instrumentation and in data collection and analysis are needed. A review of the holography method is given with a focus on X-ray fluorescence holography. Methods for analysis of X-ray holographic data are also reviewed. An overview of the detectors relevant to X-ray measurements is also presented. An experimental apparatus for rapid acquisition of X-ray holographs using novel X-ray detectors has been developed. The integration of …

Approximate String Matching Methods For Duplicate Detection And Clustering Tasks, Oleksandr Rudniy

Dissertations

Approximate string matching methods are utilized by a vast number of duplicate detection and clustering applications in various knowledge domains. The application area is expected to grow due to the recent significant increase in the amount of digital data and knowledge sources. Despite the large number of existing string similarity metrics, there is a need for more precise approximate string matching methods to improve the efficiency of computer-driven data processing, thus decreasing labor-intensive human involvement.

This work introduces a family of novel string similarity methods, which outperform a number of effective well-known and widely used string similarity functions. The new …

Superarmed Glycosyl Donors In Chemical Glycosylation, Hemali Deepthika Premathilake

Dissertations

Only recently has the tremendous biological significance and therapeutic potential of carbohydrates and conjugates thereof (glycoproteins, glycolipids, proteoglycans, etc.) begun to emerge. As the appreciation for the biological roles of carbohydrates a growing demand for efficient and scalable methods towards the synthesis of these challenging molecules has become even more imperative. This has led to the development of a variety of expeditious strategies for oligosaccharide assembly. Amongst these strategies, the so-called armed-disarmed strategy introduced by Fraser-Reid is of particular attractiveness as it allows for chemoselective oligosaccharide synthesis. Recently, the conformational changes as well as the strategic placement of common protecting …

Hear3d: A Study Of Spatial Sounds Effect On Language Learning, Brendan Cregan

Dissertations

Spatial sound is the manipulation of audio to add the illusion of position to the source of the sound, i.e. making sounds seem to originate from behind you or from different points around a room. Headphones must be used to achieve the optimum level of 3D sound. At any time over half a billion people are learning languages with the aide of audio which is why and the study of the effect or potential effects that the spatial sounds have on language learning is particularly interesting. If the application of spatial sounds to educational audio clips could be shown to …

Sports Data Mining Technology Used In Basketball Outcome Prediction, Chenjie Cao

Dissertations

Driven by the increasing comprehensive data in sports datasets and data mining technique successfully used in different area, sports data mining technique emerges and enables us to find hidden knowledge to impact the sport industry. In many instances, predicting the outcomes of sporting events has always been a challenging and attractive work and is therefore drawing a wide concern to conduct research in this field. This project focuses on using machine learning algorithms to build a model for predicting the NBA game outcomes and the algorithms involve Simple Logistics Classifier, Artificial Neural Networks, SVM and Naïve Bayes. In order to …

Accessible Information: Advocating The Use Of Technology For Individuals With Intellectual Disability On Their Path To Individualised Services, Michelle Moloney

Dissertations

Providing people with an intellectual disability (ID), opportunities for social integration have been shown to have a reliable positive influence on their well-being (Wehmeyer et al., 2006; Bunning, 2009). A large percentage of individuals with ID are unable to read and write. For this reason in order for the person to make an informed choice the person needs to have good information presented in a way that they can understand. They may need to see tangible visual aids (video, role play, film, photographs). It may need to be demonstrated to them a number of times. This assists a person in …

Rate-Based Robust Adaptive Performance Tracking Control Of Network Flows, Xiaoyan Mei

Dissertations

Network flow control methods have been studied for years to ensure the efficient usage of network resources. By adopting a representation reminiscent of the sliding surface representation, this work explores a highly adaptive network flow control strategy. The rate-based network flow control scheme is investigated through a novel model description in the matrix notation, and guaranteed to be stable under mild assumptions. The control law has a simple form but the proof of robust stability is quite involved via the Lyapunov theory. Simulations demonstrated that the developed adaptive algorithms are robust and effective in maintaining good link price and backlog …

Analysis Of Illicit Drugs, Their Metabolites And Other Micropollutants In Water By Liquid Chromatography Tandem Mass Spectrometry, Deepika P. Panawennage

Dissertations

The goal of this project is to develop liquid chromatography tandem mass spectrometry (LC/MS/MS) methods for the analysis of different, novel micropollutants in waste water and natural water. Micropollutants are compounds that can exert adverse environmental and human health effects at low concentrations. Most of these compounds include personal care products and pharmaceuticals, such as antibiotics and controlled substances. In the first part of this study, we focused in the analysis of illicit drugs and drug metabolites because these analyses have the potential to serve as markers of drug abuse. We have detected over sixteen different illicit drugs and their …

Spectroelectrochemical Studies Of The Reductive Intermediates Of Anthraquinone-2,6-Disulfonate In Aqueous Media, Anna Weiss

Dissertations

Reactive intermediates in the reduction of anthraquinone-2,6-disulfonate (AQDS) by dithionite combine to form a transient dimer which has shown to give rise to a series of charge transfer bands in the visible range (600-750 nm). Additional wavelengths associated with these intermediate species have been observed at wavelengths 402, 444 and 510 nm. These transient intermediates are generated as dithionite decomposition products re-oxidize AQDS. Evidence of the dimer was also found in experiments in which reduction of AQDS was achieved electrochemically by the use of a potentiostat. This implies three things: 1. dithionite is not required for dimerization of reactive intermediates; …

Numerical Studies Of Supersonic Jet Impingement On A Flat Plate, Michael R. Brown

Dissertations

No abstract provided.

Continuous- And Discrete-Time Structured Malaria Models And Their Dynamics, Junliang Lu

Dissertations

No abstract provided.

A Physically-Derived Nonquasi-Static Model Of The Ferroelectric Transistor For Computer-Aided Device Simulation And Its Application In Analog Circuits, Rana M. Sayyah

Dissertations

No abstract provided.

Introduction Of Critical Stress State Criterion To Predict Bond Strength Between Frp And Concrete Substrate, Shigeyuki Ueno

Dissertations

No abstract provided.

Analysis And Mitigation Of Edge Stresses In Multi-Directional Fiber Reinforced Composite Laminates, Srikanth Sundaresh Ghantae

Dissertations

Edge delamination in composite laminates with adjacent layers oriented at different fiber angles is a major failure mode because of the existence of high interlaminar stresses and poor interlaminar properties. Mitigation of edge stresses poses a challenge even to date. This research provides a detailed analysis and a potential approach to solve this problem in a carbon/epoxy composite laminate. Two extreme laminates of stacking sequence (0_n/90_n)s and (+45_n/-45_n)s subjected to separately applied tensile and thermal loading were considered. These problems have been treated in the literature as a mathematical or bare interface …

Tunable Luminescence And White Light Emission Of Lanthanide-Doped Cawo4 And Casio3 Phosphors Prepared By Pechini And Traditional Sol-Gel Methods, Matthew Anwar Mickens

Dissertations

This study reports the synthesis, characterization, and photoluminescence properties of a calcium tungstate/molybdate (CaWO₄/MoO₄) system, and the synthetic attempts of an agrellite (NaCa₂Si₄O₁₀F) system. The objective is to modify the photoluminescence of both systems by doping with lanthanide/transition metal ions, and to convert them into phosphors with specific applications for light-emitting-diodes (LEDs). CaWO₄ is used as a host matrix to fabricate a white light phosphor. When MoO₄ is added to the system, its excitation range is extended, and its emission profile can be tuned by changing excitation wavelength. …

Modeling And Optimal Mitigation Of Impulsive Low Frequency, Meng Vang

Dissertations

Low-frequency outdoor noise is very common in urban environments and can propagate over long distances. Residents living in the vicinity of a military base and other noisy areas often are annoyed by this noise. Most of the theoretical and experimental work that have been done to study and reduce this type of noise involved the use of barriers and sound proofing the residential houses. The attenuation of acoustic waves propagating above hard surfaces over long distances depends on the shape of the surface. Therefore, the landscape is a factor in combating outdoor noise. In this dissertation, an anti-propagation approach involving …

Modeling, Simulation, And Optimization Of Diamond Disc Pad Conditioning In Chemical Mechanical Polishing, Emmanuel Ayensu Baisie

Dissertations

Chemical Mechanical Polishing (CMP) is a major manufacturing step extensively used to planarize and smooth silicon wafers upon which semiconductor devices are built. In CMP, the polishing pad surface is glazed by residues as the process progresses. Typically, a diamond disc conditioner is used to dress the pad to regenerate newer pad asperity and a desired surface profile in order to maintain favorable process conditions. Conditioner selection and the determination of the optimal conditioning parameter values to yield a desired pad surface still remain difficult problems. Various analytical process models have been proposed to predict the pad surface profile. However, …

Renewable Energy Integration: Correlating Homeowner Motivations, Casey Jerome Forrest

Dissertations

The purpose of this quantitative correlational study was to explain the relationship between homeowners' preferred leadership style and their motivation to use sustainable energy. This study utilized a quantitative correlational methodology. The researcher developed and administered a questionnaire to collect data from a convenience sample of faculty and staff homeowners from two public institutions in the Piedmont-Triad region of North Carolina. The Leadership Motivation Index Questionnaire (LMIQ) is an 11 question assessment designed to explain potential correlations between the frequency of motivational factors and preferred leadership styles. The LMIQ includes three sections (demographics, motivation, and leadership style) to access what …

Network Survivability Analysis: Coarse-Graining And Graph-Theoretic Strategies, Teshome Feyessa

Dissertations

Survivability is the ability of a system to continuously deliver essential services despite attacks, failures, or accidents that damage a significant portion of the system. Most of existing survivability measures evaluate global impact of faults on a network by averaging the loss in performance over the whole network. These approaches undermine the fact that a fault is not expected to impact all parts of the network equally. Impacts of some faults are contained in local neighborhoods while others have a global reach. In addition, graph algorithms are often computationally intensive, and even polynomial time algorithms get impractical for a fair …

Multimodal Human-Machine Interface For Haptic-Controlled Excavators, Benjamin Osafo-Yeboah

Dissertations

Since the 1940s, fluid power has been used effectively in combination with other technologies to provide power in the form of hydraulics or pneumatics for a variety of industries. One such machinery is the excavator. Although the excavator is widely used in industry, numerous design constraints make the interface less intuitive, resulting in long operator training and high cost. Further, traditional excavator-operator interfaces rely mainly on visual and to some extent auditory senses. This often leads to cognitive overload with its negative effect on performance. A haptic-controlled excavator interface has been proposed as an alternative to the traditional excavator interface. …