Digital Commons Network^™

Modeling Hydrogen Diffusion For Solar Cell Passivation And Process Optimization, Yi Zhang

Dissertations

A diffusion model for hydrogen (H) in crystalline silicon was established which takes into account the charged state conversion, junction field, mobile traps, and complex formation and dissociation at dopant and trap sites. Carrier exchange among the various charged species is a "fast" process compared to the diffusion process. A numerical method was developed to solve the densities of various charged species from the Poisson's equation that involves shallow-level dopants and one "negative U" impurity, e.g., H. Time domain implicit method was adopted in finite difference scheme to solve the fully coupled equations.

Limiting versions of the model were applied …

Elementary, Pressure Dependent Model For Combustion Of C1, C2 And Nitrogen Containing Hydrocarbons : Operation Of A Pilot Scale Incinerator And Model Comparison, Chad Sheng

Dissertations

A 140000 BTU/hr pilot scale incinerator has been constructed, tested and run; and an online sampling train capable of taking in situ data has been established. The continuous on-line analytical instruments include a CO analyzer, an NO/NOx analyzer and an 02 analyzer. In addition, two gas chromatographs with flame ionization detector are used to determine CH4, C2H2 + C2H4 and total hydrocarbon concentrations. Typical operating conditions are at an average 02 concentration of 6 - 8 %. The NO concentration ranged from 100 - 200 ppm. Approximately I ppm of CH.4 is also present at steady state operations.

The kinetic …

The Development Of The Tavistock And Tavistock-Inspired Group Relations Movement In Great Britain And The United States: A Comparative And Historical Perspective, Amy L. Fraher Edd

Dissertations

In order to gain a deeper understanding of authority, people must analyze human behavior in groups. To study these behaviors, a group relations movement was spawned approximately 60 years ago and has influenced people's thinking about leadership and authority in groups and organizations ever since. This study analyzed primary and secondary historical sources, including data from extended videotaped interviews the researcher conducted with thirteen group relations experts throughout the United States and Great Britain, as a way to reconstruct the history of a significant part of the group relations movement. These videotaped interviews are available for viewing. Specifically, the study …

Perception And Reality: An Empirical Assessment Of Navy Leadership Styles And Business Process Reengineering Outcomes, Andre D. Murphy Edd

Dissertations

Seeking to improve mission readiness and organizational effectiveness while reducing expenditures, the Department of the Navy (DoN) eliminated and reconstructed many of its business practices. Reconstruction of the military's business practices was accomplished through business process reengineering (BPR). Business process reengineering is a change strategy that provides organizations the opportunity to do “more with less.” Although doing more with less is not a new concept in military settings, the organizational change construct of business process reengineering is new. Most organizations in the private sector that attempt reengineering do not attain their intended results; the literature reveals that 50–70% of organizations …

The Relationships Between Attitude, Motivation, Anxiety, And Proficiency In English As A Second Language Of First-Year University Students In Puerto Rico, Carmen Mercedes Cortés

Dissertations

Purpose of the study. The purpose of this study was to determine the attitudes, motivation, and anxiety levels of first-year university students toward the learning and use of English as a second language. The study also examined the nature of the relationships between attitudes, motivation and anxiety, and English proficiency asmeasured by the College Entrance Examination Board.

Method. A Spanish version of The Attitudes/Motivation Test Battery (Gardner, 1985a), "Espejo de Actitudes: Aprendizaje del Inglés como Segundo Idioma en Puerto Rico," was administered to first-year college students at the University of Puerto Rico, Mayagüez Campus. These students came from various …

A Descriptive Case Study : The Implementation Of A Field-Based Master's Program, Jeanne Renita Grant

Dissertations

Purpose of study. This study focuses on the implementation of the Field-based Master's Program at Midwestern Christian University. The three-step Adoption Change Model (Fullan, 1991) guided me through this innovation: (1) adoption, (2) implementation, and (3) institutionalization of the program. This 2-year study describes the program's adoption and implementation stages. Institutionalization was not included as it takes 3-10 years to occur. Three research questions guided this study.

Research questions. (1) What did the teacher training in the uses of processes look like during the initial summer session of the Field-based Master's Program? (2) What did the transfer of training …

The Design, Implementation, And Assessment Of Initial Change And Growth In A Local Voluntary Organization And Its Members, Tracy Ann Weber

Dissertations

Problem. During the past 30 years, Americans have steadily reduced their participation in the traditional forms of community involvement, such as clubs, associations, and organizations, that bring people together to effectively pursue a shared objective. In this postmodern society, leaders of community and nonprofit organizations find they are asking themselves difficult questions about the most effective methods of fulfilling their mission and simultaneously meeting members' changing needs. Participatory volunteer-run organizations, such as a local branch or chapter of a national organization, face many challenges, making it hard to establish and maintain there organizations. They demand great energy of leaders, …

Academic Persistence And Attrition Among Freshman Traditional And Non-Traditional Students At A Public Midwestern Commuter University, Arnold W. Illanz

Dissertations

Problem. This research examined student background characteristics, student social and institutional integrations, and their relation to attrition rates of freshman students at a public Midwestern commuter university.

Method. A quantitative research methodology based on empirical data collection was used utilizing a 101-question research instrument consisting of two sections: student demographic, and five factorially derived scales developed by Pascarella and Terenzini (1980) which operationalized Tinto's (1975) conceptual model of college student withdrawal. Chi-square, analysis of variance, and Pearson product-moment correlation were used to identify factors related to student academic persistence and attrition.

Results. The study found that, in general, factors external …

The Truth Claims Of Online Higher Education A Social Constructionist Analysis, Thomas Wells Brignall Iii

Dissertations

No abstract provided.

Visionary Leadership: The Importance In The Public Sector From The Perspective Of City Managers, Nancy L. Quarles

Dissertations

The purpose of this qualitative study is to apply Sashkin’s Visionary Leadership model to City Managers, with an emphasis on how the city manager puts the vision into action in local government. There is much talk that government leaders need to have a vision so that their organization will work more efficiently and effectively. More government agencies should seek to instill visionary leadership, much as a growing number of businesses have done. The City Manager must cope with sweeping changes in city government that have resulted from rapid growth, elected officials’ expectations, new technology, unions, citizen demands, and the need …

The Relationship Between Self-Esteem And Impostor Phenomenon Of Female Teachers For Kindergarten Through Grade 12, Sheila F. Matthews

Dissertations

Some researchers have recognized the importance of understanding women’s experiences. Some psychosocial characteristics, such as low levels of self-esteem and self-efficacy, and low success expectations have been identified as barriers for women’s career development (Betz, 1994). Because many women have continued to select careers that are considered as female-dominated (e.g., teaching) and because psychosocial characteristics and experiences of teachers such as self-esteem and the impostor phenomenon can have an influence on their students’ self-esteem, this researcher believed that this is an important topic for continued research. Although these two concepts, self-esteem and impostor phenomenon, have been documented as two unrelated …

Floating Holidays: A Novel, Christopher Joseph Torockio

Dissertations

No abstract provided.

Development Of An Integrated Photonic Sensor For Monitoring Hazardous Organics, Dianhong Luo

Dissertations

In this study, an integrated photonic sensor has been designed and fabricated for the purpose of monitoring hazardous organics in the environment. The operation of the sensor is based on the principles of the Mach-Zehnder interferometry. The sensor consists of a patterned waveguide structure made of phosphosilicate core and silica cladding. LPCVD processes were developed to produce undoped cladding and doped core silicon dioxide films. Diethylsilane (DES), Trimethylphosphite (TMP) and oxygen were used as the precursors for the deposition process. The effects of the O₂/DES ratio and deposition temperature on the properties Of SiO₂ films were investigated. …

Buckling Of Composite Conical Shells Under Combined Axial Compression, External Pressure, And Bending, Youngjin Chung

Dissertations

Conical shells are extensively used in space crafts, robots, shelters, domes, tanks, and in machinery or devices (e.g. as Belleville washers). Thus, the design of minimum weight, maximum strength, stiffened conical (and cylindrical) shells under combined loads has long been of interest to designers. The objective of this study is to improve the strength of conical shells and reduce the weight of the structure. Buckling of composite conical shells subjected to combined axial loading, external pressure, and bending is investigated using energy and finite element methods. The conical shells have single and multiple layers, different cone angle, length, and radius. …

The Structure And Stability Of Expanding And Converging Near-Stoichiometric Flames, Raymond Addabbo

Dissertations

The stability of expanding and converging premixed flames is investigated theoretically. These configurations are inherently unsteady and represent simple examples of positively (expanding) and negatively (converging) stretched flames. A new model is employed in this study that incorporates both hydrodynamic and diffusional-thermal effects. The model expands earlier works by incorporating variable transport properties, variations in the mixture strength and a more realistic dependence on viscosity.

The expanding flame is shown to remain stable at small radii provided the thermal diffusivity exceeds the mass diffusivity of the deficient reactant. However, once the flame achieves a critical size, a cellular instability appears, …

Arq Protocol For Joint Source And Channel Coding And Its Applications, Bin He

Dissertations

Shannon's separation theorem states that for transmission over noisy channels, approaching channel capacity is possible with the separation of source and channel coding. Practically, the situation is different. Infinite size blocks are needed to achieve this theoretical limit. Also, time-varying channels require a different approach. This leads to many approaches for source and channel coding. This dissertation will address a joint source and channel coding that suits Automatic Repeat Request (ARQ) application and applies it to packet switching networks. Following aspects of the proposed joint source and channel coding approach will be presented:

1. The design of the proposed joint source …

Evolutionary Polymorphic Neural Networks In Chemical Engineering Modeling, Li Gao

Dissertations

Evolutionary Polymorphic Neural Network (EPNN) is a novel approach to modeling chemical, biochemical and physical processes. This approach has its basis in modern artificial intelligence, especially neural networks and evolutionary computing. EPNN can perform networked symbolic regressions for input-output data, while providing information about both the structure and complexity of a process during its own evolution.

In this work three different processes are modeled: 1. A dynamic neutralization process. 2. An aqueous two-phase system. 3. Reduction of a biodegradation model. In all three cases, EPNN shows better or at least equal performances over published data than traditional thermodynamics /transport or …

Asymptotic Methods In Applied Waveguide Problems, Helen Martynov

Dissertations

Some of the most challenging problems in acoustics and electromagnetics involve the study of scattered fields in waveguides caused by targets of elaborate shape. The complexity of the resulting scattered field depends on the geometry of the scatterer, and exact solutions exist only for the simple geometries.

The asymptotic methods developed in this dissertation give the approximate solutions for the scattered fields in two practically important geometries: an object placed inside a stratified waveguide, and a waveguide with multiple abrupt width transitions. The solutions for these geometries are obtained by approximating the field near the target or junction by the …

Integration Of E-Business Strategy For Multi-Lifecycle Production Systems, Yanchun Luo

Dissertations

Internet use has grown exponentially on the last few years becoming a global communication and business resource. Internet-based business, or e-Business will truly affect every sector of the economy in ways that today we can only imagine. The manufacturing sector will be at the forefront of this change. This doctoral dissertation provides a scientific framework and a set of novel decision support tools for evaluating, modeling, and optimizing the overall performance of e-Business integrated multi-lifecycle production systems. The characteristics of this framework include environmental lifecycle study, environmental performance metrics, hyper-network model of integrated e-supply chain networks, fuzzy multi-objective optimization method, …

Saturation Routing For Asynchronous Transfer Mode (Atm) Networks, Jose Luis Ucles

Dissertations

The main objective of this thesis is to show that saturation routing, often in the past considered inefficient, can in fact be a viable approach to use in many important applications and services over an Asynchronous Transfer Mode (ATM) network. For other applications and services, a hybrid approach (one that partially uses saturation routing) is presented. First, the minimum effects of saturation routing are demonstrated by showing that the ratio, defined as f, of routing overhead cells over information cells is small even for large networks. Second, modeling and simulation and M/D/l queuing analysis techniques are used to show that …

Structural, Transport And Magnetic Studies Of Perovskite Bi1-X Cax Mn O3, Hyungje Woo

Dissertations

This dissertation presents an investigation of the fundamental physics of the perovskite system Bi_1-xCa_xMn0₃. This material belongs to a group of simple perovskites called the manganites which are of technological importance for magnetic device applications as read-head sensors.

The Bi_1-xCa_xMnO₃ system is known to exhibit charge ordering (and high sensitivity to magnetic fields) for a much broader range of x than the well-characterized La_1-xCa_xMnO₃ system. However, the properties of Bi_1-xCa_xMnO₃ over the entire doping range are not well understood. …

Detection Of Vapor Phase Mercury Species By Laser Fluorescence Methods, Xiaomei Tong

Dissertations

Elemental and compound mercury are often both volatile and air stable. Several mercury species emissions have been identified in off-gases from industrial processes. The high toxicity of mercury species and the presence of mercury species in municipal waste and coal have prompted a demand for a cost-effective, accurate, and rugged technique for real-time, continuous detection of mercury species vapors. Real-time, continuous emission measurements are important for process control, monitoring, and remediation. At present, there is no commercial continuous emission monitoring (CEM) technique or instrumentation to reliably monitor volatile mercury species emissions from industrial stacks. Conventional measurement methods, such as cold …

High Solid Loading Aqueous Base Metal/Ceramic Feedstock For Injection Molding, Mohammad Behi

Dissertations

Increasing volume fraction of metal powder in feedstock provided lower shrinkage. Reduction of the shrinkage results in better dimensional precision. The rheology of the feedstock material plays an important role to allowing larger volume fractions of the metal powder to be incorporated in the feedstock forinulations. The viscosity of the feedstock inainly depends on the binder viscosity, powder volume fraction and characteristics of metal powder.

Aqueous polysaccharide agar was used as a baseline binder system for this study.The effect of several gel-strengthening additives on 1.5wt% and 2wt% agar gel was evaluated. A new gel-strengthening additive was found to be the …

Electrostatic Micro Actuators For Mirror And Other Applications, Xingtao Wu

Dissertations

Micro-electro-mechanical systems (MEMS) based electrostatic micro actuators are becoming important building blocks for innovations in optical signal processing and computing systems due to their inherently small size, high density, high speed and low power consumption. Generally, the principle of operation in these systems can be described as: an electrostatic attractive force causes a mechanical rotation, translation or deformation of a mirror plate, controlling the power, phase or direction of a light beam while it propagates through some medium or through free space. The fast paced, competitive research and development efforts widely being undertaken, both in academia and industry, are demanding …

Modeling And Experimental Validation Of A Single-Feed Semi-Batch Precipitation Process, Ernesto Uehara-Nagamine

Dissertations

Crystallization is a widely practiced unit operation throughout the chemical and pharmaceutical process industries. Despite its widespread application, crystallization still suffers a disproportionate number of process difficulties due to the complexity of the steps involved in the process. In particular, the final characteristics of the product are strongly affected by the mixing conditions during the process. The development of a validated modeling approach would be highly valuable for the successful prediction of the crystal characteristics under differing mixing conditions.

In the present work, the single-feed semi-batch precipitation process of barium sulfate in a stirred tank was experimentally studied and numerically …

“In Our Own Words”: Exploring Female Psychosocial Student Development, Elizabeth Maier Marietta

Dissertations

On a continual basis student affairs professionals apply Chickering’s (1969) theory of psychosocial student development theory to their work with college students (Evans, Forney, & Guido-DiBrito, 1998; Pascarella & Terenzini, 1991). In order to best serve their students it is, therefore, critical that the theory be accurate and representative. While Chickering’s theory has received much acclaim, it has also been criticized throughout the years, particularly in the area of female student development (Straub, 1987; Straub & Rodgers, 1986; Taub, 1995; Taub & McEwen,1991). The purpose of the present study is to supplement existing theory by moving away from conceptual assertions …

Effects Of Software Use On The Preparation Of The Individualized Education Programs (Iep’S), Nancy Ann Beukema

Dissertations

Special educators are required to process paperwork mandated by federal regulations for students with special needs. The Individuals with Disabilities Act of 1997 (IDEA ’97, Public Law 105-17) requires the evaluation of students with special needs occur as frequently as their non-disabled peers. An annual review is also mandated for each student’s individualized educational program (IEP), in order to reevaluate the future goals and objectives of the IEPs. A student identified as needing special education services is one who needs specially designed instruction and this instruction must meet the specific individual needs of that student. IDEA ‘97 mandates the need …

The Economic Cost Of Depressive Disorders: Evidence From A Large Midwest Public University, Alketa Hysenbegasi

Dissertations

This dissertation aims to estimate the total cost of depression and the benefits of its treatment per diagnosed depressed student in Western Michigan University. To accomplish this, first, I measure the overall impact of depression and the effectiveness of its treatment on the student school performance. The empirical evidence show that diagnosed depression decreases student GPA by 0.48 points (almost a half grade), but this impairment is reduced by treatment about 0.43 points. Further, I develop and validate different measurements of student school performance and I observe that the negative effect of diagnosed depression and the positive effect of treatment …

A Systems Approach To Designing An Internship Model That Benefits The Sponsoring Organization, Peter-Cornelius Dams

Dissertations

No abstract provided.

Parametric Study Of Heavy Metal Partitioning In A Pilot Scale Incinerator Burning Simulated Municipal Solid Waste, Sukrut S. Thipse

Dissertations

Incineration is a combustion process used to convert toxic waste to benign gases and residue in presence of excess air. The products of the incineration process are bottom ash, fly ash and the flue gas. Most of the metal-based phases formed in incineration are toxic and their emissions need to be strictly controlled. Therefore, behavior of metal species during incineration must be well understood. Such understanding is possible based on the experimental identification of the metal phases formed in the waste combustion and determination of their concentration in various incineration products.

A pilot-scale incinerator of 140,000 Btu/hr capacity was constructed, …