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Synthesis And Characterization Of Low Pressure Chemically Vapor Deposited Boron Nitride And Titanium Nitride Films, Narahari Ramanuja

Dissertations

This study has investigated the interrelationships governing the growth kinetics, resulting compositions, and properties of boron nitride (B-C-N-H) and titanium nitride (Ti-N-Cl) films synthesized by low pressure chemical vapor deposition (LPCVD) using ammonia (NH₃)/triethylamine-borane and NH₃/titanium tetrachloride as reactants, respectively.Several analytical methods such as the FTIR, UVNisible spectroscopy, XPS, AES, RBS, SEM, and XRD were used to study the stoichiometry and structure of the deposited films.

The B-N-C-H films were synthesized over a temperature range of 300 to 8500C at various flow rate ratios of the reactants and total pressure range of 50 to 150 mTorr. …

Interaction Of A Vortex Pair And A Free-Surface : Numerical Simulation, Haisheng Ruan

Dissertations

The interaction between a submerged vortex pair with a deformable free-surface in a viscous, incompressible fluid is directly simulated and the flow is thoroughly analyzed. This is a time-dependent nonlinear free-surface problem which we solve numerically by integrating the two-dimensional Navier-Stokes equations and using boundary-fitted coordinates capable of handling large free-surface deformations. In particular, the numerical simulation of the flow at relatively high Reynolds numbers (Re = 500,1000, 2000 ) and relatively high Froude numbers (Fr = 1. 125, Fr = 2.0) is investigated and analyzed for the first time. Details are given regarding the space-time deformation of …

The Impact And Fate Of Aqueous Sodium Nitrate On Hydrocarbon Flames, Ann Marie Flynn

Dissertations

This study examined the impact and fate of sodium (fed as an aqueous nitrate solution) in fuel-rich methane/air and methane/methyl chloride/air flames as a function of equivalence ratios that experienced diffusion of air from the surroundings. The flames were stabilized on a slotted, uncooled burner. The data set was divided into profiles of relative sodium atom concentrations, temperatures, and selected stable species concentrations. The flames were simulated using a modified version of the Sandia FORTRAN program for modeling steady laminar one-dimensional premixed flames complete with detailed mechanisms. The results showed that maximum sodium atom concentration in the flame is decreased …

Multimedia Modeling Of Organic Contaminants In The Passaic River Watershed, Lansana Coulibaly

Dissertations

A dynamic fate and transport multimedia environmental model was developed and applied to assess the release of five priority contaminants in the Passaic River Watershed, including: napthalene, toluene, trichloroethylene, 1-1-1 trichloroethane and xylene. The model uses the current releases of contaminants as well as cross-boundary advection to determine the fate and environmental distribution of these chemicals in the watershed. The model was developed using a dynamic fugacity approach in order to allow for scenario analysis such as source reductions and no-action alternatives. This modeling effort is expected to achieve a comprehensive assessment of contaminants not only in the proximity of …

Component-Based Software Engineering, Zhiyuan Wang

Dissertations

To solve the problems coming with the current software development methodologies, component-based software engineering has caught many researchers' attention recently. In component-based software engineering, a software system is considered as a set of software components assembled together instead of as a set of functions from the traditional perspective. Software components can be bought from third party vendors as off-the-shelf components and be assembled together.

Component-based software engineering, though very promising, needs to solve several core issues before it becomes a mature software development strategy. The goal of this dissertation is to establish an infrastructure for component-based software development. The author …

Modeling, Design And Fabrication Of Thin-Film Microcrystalline Silicon Solar Cells, Wei Chen

Dissertations

The modeling, design and fabrication of low-cost thin-film microcrystalline silicon(µcSi) solar cells is studied in this thesis. The cell, considered in this investigation, utilizes low-cost glass as the substrate and microcrystalline Si (µc-Si) as the active layer. A comprehensive refractive index (n) and extinction coefficient (k) model of silicon as function of doping, temperature and wavelength is developed to assist the optical design of the cell. In order to obtain acceptable short circuit current density (Jsc) from the cell, it is found that the thickness of the silicon thin film should be more than 10µm. To get the best light …

Identification And Classification Of Coryneform Bacteria Isolated From Bovine Mammary Glands, Jeffrey L. Watts

Dissertations

Coryneform bacteria are frequently isolated from bovine mastitis and these infections are associated with economic losses. Corynehacterium bovis, a lipid requiring species, has been the most frequently isolated coryneform from the milk of infected bovine mammary glands. However, the taxonomic status of this organism is uncertain. In the current study, a polyphasic approach was used to identify coryneform bacteria isolated from bovine mastitis and determ ine the phylogenetic relationships among the identified species. A total of 212 coryneform bacteria isolated from bovine mastitis was obtained from mastitis reference laboratories in the United States and Canada. Presumptive identification based upon …

Optimum Design And Machining Parameters Of A Permanent Magnet Brushless Dc Linear Motor As A Cnc Feed Drive, William Tereshkovich

Dissertations

A new heuristic has been developed to determine optimal operating parameters applied to a permanent magnet brushless DC linear motor (PMBDCLM) as a CNC feed drive. An FEA model has been developed utilizing an -electromagnetic postprocessor to provide performance output of a PMBDCLM and DC servomotor. Based on the developed FEA models, velocity results have been utilized to provide feedrate levels for design of experiments (DOE). DOE has been conducted to provide force, tolerance, and surface finish data necessary for the performance comparison of a DC servo motor/ballscrew equipped CNC vertical milling machine and a PMBDCLM equipped CNC vertical milling …

Experiment, Thermodynamic Properties And Modeling On Combustion Of Methyl Tert-Butyl Ether : Isobutane And Isobutene And Thermodynamic Properties Of Chloro Alkanes And Alkenes, Chiung-Ju Chen

Dissertations

The reaction systems: methyl tert-butyl ether (MTBE) unimolecular decomposition, MTBE radicals + O₂, tert-butyl radical +O₂, isobutene + HOO. (HO₂),isobutene + OH, sobutene-OH adducts + O₂, and allylic isobutenyl radical + O₂, are important systems in the understanding the oxidation chemistry of MTBE, tertiary butyl radical (C3C.), and sobutene, are analyzed. Thermochemical parameters are determined by ah initio Møller-Plesset (MP2(full)/6-31g(d)), complete basis set model chemistry (CBS-4 and CBS-q with MP2(full)/6-31g(d) and B3LYP/6-31g(d) optimized geometries), density functional (B3LYP/631g(d)), semi-empirical MOPAC (PM3) molecular orbital calculations, and by group additivity estimation. Thermochemical …

Performance-Based Seismic Engineering Of Low And Medium-Rise Steel Frames, Saeid Rashidi

Dissertations

The performance level of low and medium-rise steel frames designed according to the common force/strength approach of the UBC or NEHRP is determined. Several combinations of soil profile type, lateral-force-resisting system, and frame-member proportioning are included in the designs.

To evaluate the expected damage, nonlinear models of the designed frames are subjected to a number of actual and simulated ground motion accelerograms and appropriate structural response parameters such as, interstory drift, ductility demand, and dissipated hysteretic energy are obtained. In addition, a modified form of Park-Ang damage index is calculated for moment-resisting frames. The seismic performance of the steel frames …

Development And Application Of Dynamic Models For Predicting Transit Arrival Times, Yuqing Ding

Dissertations

Stochastic variations in traffic conditions and ridership often have a negative impact in transit operations resulting in the deterioration of schedule/headway adherence and lengthening of passenger wait times. Providing accurate information on transit vehicle arrival times is critical to reduce the negative impacts on transit users. In this study, models for dynamically predicting transit arrival times in urban settings are developed, including a basic model, a Kalman filtering model, link-based and stop-based artificial neural networks (ANNs) and Neural/Dynamic (ND) models. The reliability of these models is assessed by enhancing the microscopic simulation program CORSIM which can calculate bus dwell and …

Reconfiguration And Tool Path Planning Of Hexapod Machine Tools, Zhenqun Li

Dissertations

Hexapod machine tools have the potential to achieve increased accuracy, speed, acceleration and rigidity over conventional machines, and are regarded by many researchers as the machine tools of the next generation. However, their small and complex workspace often limits the range of tasks they can perform, and their parallel structure raises many new issues preventing the direct use of conventional tool path planning methods. This dissertation presents an investigation of new reconfiguration and tool path planning methods for enhancing the ability of hexapods to adapt to workspace changes and assisting them in being integrated into the current manufacturing environments.

A …

The Influence Of High Performance Matrices On Fracture Behavior Of Concrete, Pusit Lertwattanaruk

Dissertations

Modification of cement matrices by the addition of micro particle pozzolanic materials such as silica fume and fly ash is known to improve the strength of concrete, but its contributions to fracture behavior remains unclear. In this study, the influence of replacing cement by silica fume and fly ash on the cement matrix-coarse aggregate interfacial bond, compressive stress-strain behavior and fracture behavior of concrete is investigated.

While the linear elastic fracture mechanics (LEFM) concept is not appropriate for concrete, a nonlinear fracture model based on the load vs. load-line deflection and the load vs. crack-mouthopening displacement (CMOD) responses of the …

Collaborative Software Agents Support For The Texpros Document Management System, Jrtian Lin

Dissertations

This dissertation investigates the use of active rules that are embedded in markup documents. Active rules are used in a markup representation by integrating Collaborative Software Agents with TEXPROS (abbreviation for TEXt PROcessing System) [Liu and Ng 1996] to create a powerful distributed document management system. Such markup documents with embedded active rules are called Active Documents. For fast retrieval purposes, when we need to generate a customized Internet folder organization, we first define the Folder Organization Query Language (FO-QL) to solve data categorization problems. FO-QL defines the folder organization query process that automatically retrieves links of documents deposited into …

Utilization Of Municipal Solid Waste Incinerator Fly Ash In Cement Mortars, Manaskorn Rachakornkij

Dissertations

Disposal of municipal solid waste has become a major problem in many countries around the world. With the benefits of substantial weight and volume reduction and potential energy recovery, incineration has become a promising municipal solid waste (MSW) management option. Despite the fact that incineration reduces volume and mass of the wastes by as much as 80%, there are still residues to be properly managed. This research is aimed at evaluating the potential of different types of MSWI fly ash from an incineration facility to be used in cement mortars by using existing standard test methods for cement and coal …

Space/Time/Frequency Methods In Adaptive Radar, Christopher D. Peckham

Dissertations

Radar systems may be processed with various space, time and frequency techniques. Advanced radar systems are required to detect targets in the presence of jamming and clutter. This work studies the application of two types of radar systems.

It is well known that targets moving along-track within a Synthetic Aperture Radar field of view are imaged as defocused objects. The SAR stripmap mode is tuned to stationary ground targets and the mismatch between the SAR processing parameters and the target motion parameters causes the energy to spill over to adjacent image pixels, thus hindering target feature extraction and reducing the …

Polymer Pyrolysis And Oxidation Studies In A Continuous Feed And Flow Reactor : Cellulose, Polystyrene, And Polyethylene, Byung-Ik Park

Dissertations

A dual zone, continuous feed tubular reactor is developed to assessthe potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer powder (cellulose,polystyrene, or polyethylene) is fed continuously into a volatilization oven where it fragments and vaporizes under continuous steady state conditions. The gas phase polymer fragments flow directly into a second, main flow reactor oven and undergo further pyrolysis and oxidation reaction. Temperatures in the main flow reactor are varied independently of the volatilization zone to observe conditions needed to convert the initial polymer fragmentsto CO₂ and H₂O. Combustion products …

Multi-User Detection For Multi-Rate Ds/Cdma Systems, Jinwen Ma

Dissertations

Wireless cellular communication is witnessing a rapid growth in market, technology and range of services. Current and future demands for wireless communication services motivate the need for handling multi-media traffic types. In a multimedia communication system, users with different and even time-varying rates and quality of services (QoS) requirements, such as voice, image and data, must be accommodated. The use of Spread Spectrum modulation with Code Division Multiple Access (CDMA) technology is an attractive approach for economical spectrally efficient and high quality cellular and personal communication services. This dissertation explores the technologies of applying different interference cancellation techniques to multi-rate …

Hytexpros : A Hypermedia Information Retrieval System, Hong Shen

Dissertations

The Hypermedia information retrieval system makes use of the specific capabilities of hypermedia systems with information retrieval operations and provides new kind of information management tools. It combines both hypermedia and information retrieval to offer end-users the possibility of navigating, browsing and searching a large collection of documents to satisfy an information need. TEXPROS is an intelligent document processing and retrieval system that supports storing, extracting, classifying, categorizing, retrieval and browsing enterprise information. TEXPROS is a perfect application to apply hypermedia information retrieval techniques. In this dissertation, we extend TEXPROS to a hypermedia information retrieval system called HyTEXPROS with hypertext …

In-Line Measurement Of Solibility Of Physical Blowing Agents In Thermoplastic Melts As Related To Extrusion Foaming, Qiang Zhang

Dissertations

A novel in-line method for measuring physical blowing agent solubility in thermoplastic melts in extrusion foaming equipment has been developed in this study. This method uses video microscopy in connection with a foaming extruder (single or twin-screw) to generate solubility data by observing the onset of gas bubble formation/dissolution. This method offers a number of advantages over the existing conventional methods. It can be easily used to obtain solubility data for many foamable thermoplastic-physical blowing agent systems at high pressure and temperature near actual foaming conditions. Data generated using this method could be directly used to characterize and control a …

Finite Fraction Method For Tracking Desinfection By-Product Precursors In Water Treatment, Doanh Van

Dissertations

Dissolved Organic Matter (DOM) has been the subject of recent regulatory activities and agenda. Among them are the Infonnation Collection Rule (ICR), the Disinfectants/Disinfection By-Product Rule (D/DBPR) and the Interim Enhanced Surface Water Treatment Rule (ESWTR). Both the latter two have provisions to limit the formation of disinfection by-products (DBP) by controlling reactivity and removal of DOM or both. Brief regulatory review of these rules was given.

Although the topic of DBP formation potential and DBP precursor removal have been studied by many researchers since Rooks (1974), the efficacy of methods that have been developed to date has been handicapped …

Integrated Product And Process Development Methodologies For Environmentally Conscious Electronic Products, Pingtao Yan

Dissertations

This research focuses on integrated product and process development (IPPD) methodologies for environmentally conscious electronic products. After a review of current research issues in the field of product and process development, a generic framework for IPPD is proposed which describes most of the concerned issues formally as constrained optimization problems. These problems may include such optimization objectives as cost, benefit, and environmental impact. Based on this framework, an IPPD methodology is proposed as a systems approach to competitive and environmentally conscious product and process development. A case study on personal computer development is performed illustrating how to apply the methodology …

Experimental Studies And Modeling Of Mechanical Properties And Morphologies Of In Situ Polymer Composites, Zhigang Li

Dissertations

In this study, a series of experiments was set up in order to analyze the morphology development and mechanical properties of poly(ethylene terephthalate) (PET)/ liquid crystalline polymer (LCP) blends. Simulations of the injection molded blends at various process conditions were performed using CMOLD. In order to determine the effect of the processing parameters on the deformation of the LCP domains during the injection molding, a new analytical method to analyze the melt flow in the advancing melt front (AMF) region was developed. By combining the simulations of the injection molding and analysis of the melt flow in the AMF region, …

Data Hiding In Multimedia - Theory And Applications, Mahalingam Ramkumar

Dissertations

Multimedia data hiding or steganography is a means of communication using subliminal channels. The resource for the subliminal communication scheme is the distortion of the original content that can be tolerated. This thesis addresses two main issues of steganographic communication schemes:

1. How does one maximize the distortion introduced without affecting fidelity of the content?

2. How does one efficiently utilize the resource (the distortion introduced) for communicating as many bits of information as possible? In other words, what is a good signaling strategy for the subliminal communication scheme?

Close to optimal solutions for both issues are analyzed. Many techniques …

From Warriors To Wingtips: The Leadership Transition Of Retired Officers Into The Public Sector, Lynn M. Eldred Edd

Dissertations

For personal and financial reasons some retired military officers seek second careers in the public sector. In entering local government, they are leaving a unique organization, and encountering a very different organizational culture. This study used grounded theory methodology to identify the key military leadership strategies and behaviors learned by military officers and to examine their applicability to local government. It focused on eleven retired naval and marine officers who served twenty or more years, attained a rank of lieutenant commander or major and above, and had worked in local San Diego government at the mid-management or executive level less …

Educational Brain Research As Compared With E.G. White's Counsels To Educators, Linda Bryant Caviness

Dissertations

Purpose. The purpose of this study was threefold: to review current, education-relevant brain research; to review the educational writings of Ellen G. White for major emerging themes/principles; and to compare these findings for similarities and differences.

Method and Results. Using an inductive process, the synthesis and comparison revealed 15 themes from brain research and 12 principles from White's writings from the middle 1800s and early 1900s.

Comparison of the two lists revealed alignment on eight themes/principles, nonalignment on three themes/principles, and partial-alignment on seven themes/principles.

Aligned themes/principles included: body and mind function as one; exercise and movement are vital …

Survey Of Nigerian University Student Affairs Services: A Comparison Of Students' Perceived Service Importance And The Students' Level Of Satisfaction, Michael Adewale Adeniyi

Dissertations

Problem. Nigerian university student-affairs serviceshave been characterized by negative campus activism, violent demonstrations, and the destruction of lives and properties, the result of which led to the closing down of many Nigerian universities. Thus far, little empirical data exist regarding the student personnel servicesavailable to students at Nigerian universities, the importance of student-affairs services, or the level of student satisfaction with these services.

Methods. A quantitative survey methodology was used to assess 35 student-affairs services. A developed and validated survey instrument, the Student ServicesQuestionnaire (SSQ), was administered to collect data from currently registered undergraduate and graduate students of …

Students' Mental Models Of Electricity In Simple Dc Circuits, Andrew C. Isola Iii

Dissertations

This study presents the results of research into middle school students' knowledge about the nature and mechanisms of action of electricity in simple DC circuits. Sixth, seventh, and eighth graders (n=99) were asked a series of questions about the roles of bulbs, batteries, wires, and electricity in circuits. Almost half the number of students (n=42) were found to have used detailed, well-defined, and logically consistent mental models based on their responses. A total of 15 different detailed mental models were documented in these students that belonged to one of four different general model types: (1) round trip flow using both …

A Comparison Of International And U.S. Students In Apa-Accredited Programs: Acculturation, Counseling Self-Efficacy And Role Difficulties In Supervision, Johanna E. Nilsson

Dissertations

There has been a call in the multicultural supervision literature to enhance the understanding of minority students’ unique training needs and develop appropriate theories and models of training for these students (Leong & Wagner, 1994; McNeill, Horn, & Perez, 1995). Although a few researchers have empirically examined differences between U.S. majority and minority students in multicultural supervision (Cook & Helms, 1988; Vander Kolk, 1974), virtually no empirical studies have been published on international students’ training experiences.

The main purpose of the present study was to advance knowledge regarding the training needs of international students in APA-accredited programs in psychology. It …

Detection And Robustness Of Digital Image Watermarking Signals : A Communication Theory Approach, George F. Elmasry

Dissertations

The detection and robustness of the watermark signal is studied from a communications point of view. The contributions of this dissertation are presented in two parts. The first part, which covers the detection aspect, introduces a new digital image watermarking approach that embeds meaningful information in a copyright protection watermark signal; demonstrates the need to approach the watermark signal as a power-constrained signal; studies the relationship between the watermark signal dimension and the image capacity to the signal; explains the similarities and differences between detecting the watermark signal and detecting a signal over a spread-spectrum communication channel; and analyzes the …