Physical Sciences and Mathematics Commons^™

Uncertainty Analysis In Ecological Risk Assessment Modeling, Tepwitoon Thongsri

Dissertations

A probabilistic approach employing Monte Carlo simulations for assessing parameter and risks as probabilistic distributions was used in an ecological risk assessment (ERA) model to characterize risk and address uncertainty. This study addresses the following sources of uncertainty: parameter inputs in the ERA models, risk algorithms and uncertain input concentrations. To achieve this objective, both sensitivity and uncertainty analyses are being conducted. Monte Carlo simulations were used for generating probabilistic distributions of parameter and model uncertainty. All sensitivity, uncertainty, and variability analyses were coded in Visual Basic as part of the ERA model software version 2001, which was developed under …

Mixing Enhancement By Dual Speed Rotating Stirrer, Arnaud Goullet

Dissertations

Stirring is a well-known means of fluid mixing due to the emergence of complex patterns in the flow, even at low Reynolds numbers. In this work, we consider a stirrer rotating along a circular trajectory at constant speed. The fluid flow, considered incompressible, inviscid and two dimensional (in a circular container), is modeled by a point vortex model consisting of a vortex rotating in a circular container at constant angular speed. The mixing problem is addressed by considering the Hamiltonian form of the advection equations formulated in a frame of reference moving with the vortex. The dynamics of passive fluid …

Enriching And Designing Metaschemas For The Umls Semantic Network, Li Zhang

Dissertations

The disparate terminologies used by various biomedical applications or professionals make the communication between them more difficult. The Unified Medical Language System (UMLS) of the National Library of Medicine (NLM) is an attempt to integrate different medical terminologies into a unified representation framework to improve decision making and the quality of patient care as well as research in the health-care field. Metathesaurus (META) and Semantic Network (SN) are two main components of the UMLS system, where the SN provides a high-level abstract of the concepts in the META.

This dissertation addresses three problems of the SN. First, the SN's two-tree …

Nonlinear Long-Wave Interfacial Stability Of Two-Layer Gas-Liquid Flow, Tetyana Segin

Dissertations

The flow of two immiscible viscous fluids in a thin inclined channel is considered, in either a cocurrent or countercurrent regime. Following the air-water case, which is found in a variety of engineering systems, we allow the upper fluid to be either compressible or incompressible. The disparity of the length scales and the density and viscosity ratios of the two fluids is exploited through a lubrication approximation of the conservation of mass and the Navier-Stokes equations. As a result of this long-wave theory, a coupled nonlinear system of partial differential equations is obtained that describes the evolution of the interfacial …

Studies Of Atomic And Molecular Dynamics Using Photoelectron Spectroscopy, Sophie E. Canton

Dissertations

Photoexcitation and photoionization studies of free atoms and molecules in the gas phase provide a unique view into various aspects of radiation-matter interactions that are used as basic building blocks in many branches of physics, such as Solid State, Plasma Physics, Photochemistry or Astrophysics. With the advent of third generation synchrotron light sources delivering high photon flux (>10¹⁵ photons/s) with unprecedented resolving power over a broad energy range, it has become possible to investigate in great detail not only the internal structure of the targets, but also the dynamics of the process. Born in the 1960s,photoelectron spectroscopy specifically …

Chemical And Isotopic Investigation Of Groundwater In Eastern United Arab Emirates (Uae), Ahmed Ali Abdalla Murad

Dissertations

UAE is located at the southeast of Arabian Peninsula. Two main aquifers occupy the study area: the Eastern Gravel Plain and Ophiolite aquifer. Increasing salinity of groundwater and depletion of aquifers are a major concern in the UAE. Previous studies suggest that groundwater, particularly in the Eastern Gravel Plain aquifer, is affected by seawater intrusion and evaporation. Isotopes of oxygen, hydrogen, carbon and chlorine, and chemical analyses were used to investigate this problem in detail. Samples of groundwater from the Eastern Gravel Plain aquifer have R³⁶Cl values in the range of 13.3 to 17.4 x10^-15 while those …

A Study Of The Relationship Between Transformational Leadership And Organizational Culture, Mildred Patricia Howard

Dissertations

The research study examines teachers' perspectives on leadership and Organizational Culture in elementary schools within the state of Michigan. Teachers respond to more than 90 survey questions from the Leadership Practices Inventory and the Instructional Climate Inventory.

The purpose of the study is to determine the relationship that exists between Transformational Leadership and Organizational Culture. The study also considers school size as an interval variable. Statistical tests used to determine possible relationships include F-Tests, T-Test and Canonical Correlations.

Findings suggest that additional studies may be warranted based on particular subscales of Transformational Leadership and also size as it relates to …

Virtual Teams Combining Mobile Devices With Web-Based Communication On Group Decision Making, Hyo-Joo Han

Dissertations

Organizations have moved from a face-to-face team environment to a virtual team environment using communication technology during the last decade. More and more workers use asynchronous tools (including email, discussion groups, information sharing tools, and group calendaring systems), and synchronous tools, such as instant messaging and web-based chatting features, to coordinate and share information with people within and outside of organizations. This empirical study on how virtual teams work, integrating mobile devices with web-based group communication for decision-making tasks, examines which technologies and communication modes are the best for distributed group teamwork, and, mainly, what are the predictive characteristics making …

High Resolution Solar Observations In The Context Of Space Weather Prediction, Guo Yang

Dissertations

Space weather has a great impact on the Earth and human life. It is important to study and monitor active regions on the solar surface and ultimately to predict space weather based on the Sun's activity. In this study, a system that uses the full power of speckle masking imaging by parallel processing to obtain high-spatial resolution images of the solar surface in near real-time has been developed and built. The application of this system greatly improves the ability to monitor the evolution of solar active regions and to predict the adverse effects of space weather. The data obtained by …

The Impacts Of Delphi Communication Structure On Small And Medium Sized Asynchronous Virtual Teams, Hee-Kyung Cho

Dissertations

The improvement of Internet technology has motivated distributed work groups to collaborate without meeting face to face. Although asynchronous meetings through Web-based group communications systems enable groups dispersed temporarily and geographically to collaborate more flexibly, parallel and non-linear communication among dispersed members also challenge effective and efficient group coordination. Moreover, the Web-based asynchronous meeting is distinguished not only from the face-to-face meeting but also from the synchronous computer-supported meeting in terms of coordination process. However, previous asynchronous group communications or virtual team research focused more on the comparison of this new type of meeting with the face-to-face meeting. Not many …

Development Of Supercritical Processes For Particle Coating / Encapsulation With Polymers, Yulu Wang

Dissertations

This work presents the investigation of particle coating using supercritical fluid processes as novel coating approaches to coat particles from 20 nanometers to 500 microns with different polymers. Particle coating using different supercritical technologies of a modified rapid expansion of a supercritical solution (RESS) for particle coating and a supereritical antisolvent (SAS) process was described.

In the modified RESS process for particle coating, experiments were performed using a pilot-scale supercritical apparatus, glass beads as host particles and two different polymers as coating materials. By adjusting temperature and pressure, the polymer nucleated and precipitated onto the surface of the host particles …

Statistical Study Of Solar Radio Bursts, Gelu-Marius Nita

Dissertations

The peak flux distribution of 40 years of solar radio burst data recorded by NOAA, as a function of frequency and time over a wide range of frequencies, was investigated to quantify the potential impact of radio bursts on wireless systems. Tables of fit parameters, which can be used to find burst occurrence rates in a number of frequency ranges, are presented. The typical power-law index of number density distribution, -1.8, is similar to that found in many hard X-ray studies. Significant changes were found in power-law index with frequency. The results may be useful for designers of current and …

A Robust Two-Sample Procedure To Estimate A Shift Parameter, Feridun Tasdan

Dissertations

This study estimates the location shift parameter in the two-sample problem. The classical method, Least Square(LS), obtains the shift parameter estimate under the normality assumption. A departure from normality assumption makes the estimate inefficient and unreliable. One alternative to the least square estimate is Hodges-Lehmann (HL) estimate which uses Wilcoxon ranks to estimate the shift parameter. This estimate is robust against contaminations and large outliers. The proposed method in this study combines two samples and uses convolution technique to find a density function for the combined sample. This new density function is later used in the construction of the log …

Determination Of Spatial Strata For Environmental Regulatory Purposes, John Edward Daniels

Dissertations

This dissertation introduces spatial strata modelling, a methodology that combines spatial statistics, cluster analysis, and geographic information system theories to analyze the background level of naturally occurring contaminants of concern (COCs). The objective of spatial strata modelling is to divide a geographic area of interest into mutually exclusive geographic zones (spatial strata): with each stratum representing a different level of COC concentration. An estimate of each stratum's COC concentration level, representing an upper regulatory limit, will also be provided. Data provided by the Michigan Department of Environmental Quality describing the spatial location and arsenic concentrations of 211 Michigan sites (arsenic …

Geochemical And Isotopic Characterization Of Shallow Basinal Brines From The Makgadikgadi Pans Complex, Northeastern Botswana: Determination Of The Sources Of Salinity, Loago N. Molwalefhe

Dissertations

Isotopes and chemical tracers have been used to constrain the sources and causes of salinity in shallow groundwater brine from the Makgadikgadi Basin, northeastern Botswana. The brine is massively rich in chloride and sodium, and moderately rich in carbonates, sulphate and potassium, and is distinctively poor in divalent cationic species. Various models that have been advanced to explain the origin of the brines include evaporative enrichment at the surface and density-induced infiltration, dissolution of evaporites, and trapped connate water.

This study presents the compositional variability and behaviors of ·the stable isotopes of carbon (S¹³C) and oxygen (S^{18 …}

How Secondary School Mathematics Teachers Construct An Understanding Of "Appropriate Use" Of Graphing Calculators In The Context Of Collegial Inquiry, Marcia L. Weller Weinhold

Dissertations

No abstract provided.

Irradiation Induced Order-Dis Order Transformations In Ni-Mo Alloys, Ovidiu F. Toader

Dissertations

No abstract provided.

Programming Language Trends : An Empirical Study, Yaofei Chen

Dissertations

Predicting the evolution of software engineering technology trends is a dubious proposition. The recent evolution of software technology is a prime example; it is fast paced and affected by many factors, which are themselves driven by a wide range of sources. This dissertation is part of a long term project intended to analyze software engineering technology trends and how they evolve. Basically, the following questions will be answered: How to watch, predict, adapt to, and affect software engineering trends?

In this dissertation, one field of software engineering, programming languages, will be discussed. After reviewing the history of a group of …

Selective Removal Of Nox From Catalytic Cracking Regenerator Effluent Using Wet Scrubbing With Aqueous Sodium Chlorite Solutions, Pin Gu

Dissertations

In most refineries, the flue gas from the regenerator in the fluid catalytic cracking (FCC) unit represents a key source of NOx, SOx, particulate, and CO emissions. Wet scrubbing systems have been used with great success to control particulate and SOx emissions from typical FCC regenerator flue gas. Development of relatively inexpensive and safe additives that can be used in existing scrubbing systems to oxidize and absorb NOx is important in order to increase the industrial options to meet the provisions of the Clean Air Act and recently proposed EPA rules. This paper explores the feasibility of removing NOx from …

Measurement Of The Nonlinear Refractive Index (N2) And Stimulated Raman Scattering In Optical Fibers As A Function Of Germania Content, Using The Photorefractive Beam Coupling Technique, Ferdinand Anayo Oguama

Dissertations

One of the greatest challenges in optical communication is the understanding and control of optical fiber nonlinearities. While these nonlinearites limit the power handling capacity of optical fibers and can cause noise, signal distortion and cross talk in optically amplified transmission systems, they have been equally harnessed for the development of new generations of optical amplifiers and tunable laser sources. The two prominent parameters that characterize the nonlinear properties of an optical fiber are the nonlinear refractive index n₂ and the Raman gain coefficient g_R. These parameters are related to the third order nonlinear susceptibility [x^{(3) …}

Thermochemistry And Kinetics In Pyrolysis And Oxidation Reaction Of Oxygenate Chlorocarbons, Neopentane, And Ortho-Xylene, Hongyan Sun

Dissertations

Thermochemical properties of chlorinated alcohols, chlorinated hydroperoxides and corresponding alkoxy, hydroxy alkyl radicals, peroxy and hydroperoxy alkyl radicals are determined by ab initlo and density functional calculations for modeling and optimization of complex chemical processes for combustion or incineration of chlorinated hydrocarbons. The entropy and heat capacities from vibrational, translational, and external rotational contributions are calculated by statistical mechanics, and the hindered rotational contributions to S^°₂₉₈ and C_p(T)'s are calculated by using direct integration over energy levels of the internal rotational potentials. The values of ΔH_f^°₂₉₈ are determined using isodesmic reactions …

Design And Evaluation Of A List Gathering Tool In A Web-Based Collaborative Environment, Yuanqiong Wang

Dissertations

This research focuses on how to build a "list" structure to combine individual items of information into some sort of structure that converts the individual items of information into a structure of knowledge relative to the problem. Software was designed to provide relationships among and comparisons of the contributions in a "list" structure, so that individual members of a group process will be able to understand the contributions of information made by the group as a whole.

A List Gathering Tool was designed and implemented, which is one component in a Web-based Social Decision Support System (SDSS) Toolkit. Then, a …

Design And Evaluation Of A Voting Tool In A Collaborative Environment, Zheng Li

Dissertations

This dissertation researchdesigned, implemented, and evaluated a Web-based Dynamic Voting Toolfor small group decision-making in a collaborative environment.

In this dissertation, theliterature on voting tools in current GDSS research is presented. Variousvoting theories and methods are analyzed, and the advantages and weaknessesare compared, so as to gain a better understanding of how to apply thesedifferent voting methods to diverse decision-making situations. A briefoverview of scaling theories is also given, with an emphasis on Thurstone'sLaw.

The basic features of someweb-based voting tool implementations are reviewed along with a discussionof the pros and cons of Intemet voting. A discussion of Human DynamicVoting …

Understanding The Origins Of Metastability In Thin Film Growth; Tantalum And The Early Group Vb-Vib Metals, Neme Okechukwu Nnolim

Dissertations

Tantalum (Ta) is a metal that is highly prized for its applications in a variety of industries, including the microelectronics industry, where it is largely used in thin film modifications in order to achieve various electronic, magnetic and structural capabilities in solid-state devices. Ta frequently forms metastable phases, including the well-known ß-phase, during the preparation of thin Ta films by standard film deposition methods such as sputtering and electro-deposition. In order to gain insight into Ta metastable phase formation, the Bain transformation mechanism is studied for Ta and the neighboring body centered cubic (bcc) transition metals in Groups 5 and …

Spearman Rank Regression, Jason C. Parcon

Dissertations

The main purpose of this dissertation is to obtain an estimate of the slope parameter in a regression model that is robust to outlying values in both the x - and Y-spaces. The least squares method, though known to be optimal for normal errors, can yield estimates with infinitely large MSE's if the error distribution is thick-tailed. Regular rank-based methods like the Wilcoxon method are known to be robust to outlying values in the Y -space, but it is still grossly affected by outlying values in x -space.

This dissertation derives an estimate of the slope from an estimating …

A Comparison Of Different Schemes For Selecting And Estimating Score Functions Based On Residuals, Ali A. Al-Shomrani

Dissertations

In a linear model when the errors follow a normal distribution, least squares methodology is most powerful. However, when the assumption of normality of the error distribution is not met then there exist methods which are more powerful than least squares methods. Rank-based methods form one such class. These methods depend on the selection of a score function [varphi]( u ). The correct choice of [varphi] leads to an optimal (efficient) analysis, but its selection depends on the error distribution which is not known.

In this thesis, we explore different schemes for score selection. Some of these schemes are functions …

New Graphical Approach On The Analysis Of Experimental Data, Suha Sari

Dissertations

This study presents a new graphical method to identify significant effects in factorial experiments. The proposed methods are obtained for the different cases in which the design can be of full factorial or fractional factorial and the factor levels can be pure or mixed.

We focus on the different decomposition methods, for example orthogonal components system and orthogonal contrast method, to make use of the chisquare plot which requires that the sums of squares are of the same degrees of freedom. Examples and simulations illustrating the different cases of the procedure are presented.

Image Morphological Processing, Vijayalakshmi Gaddipati

Dissertations

Mathematical Morphology with applications in image processing and analysis has been becoming increasingly important in today's technology. Mathematical Morphological operations, which are based on set theory, can extract object features by suitably shaped structuring elements. Mathematical Morphological filters are combinations of morphological operations that transform an image into a quantitative description of its geometrical structure based on structuring elements. Important applications of morphological operations are shape description, shape recognition, nonlinear filtering, industrial parts inspection, and medical image processing.

In this dissertation, basic morphological operations, properties and fuzzy morphology are reviewed. Existing techniques for solving corner and edge detection are presented. …

Fully Nonlinear Interfacial Waves In A Bounded Two-Fluid System, Lyudmyla Leonidivna Barannyk

Dissertations

We study the nonlinear flow which results when two immiscible inviscid incompressible fluids of different densities and separated by an interface which is free to move and which supports surface tension, are caused to flow in a straight infinite channel. Gravity is taken into consideration and the velocities of each phase can be different, thus giving rise to the Kelvin-Helmholtz instability. Our objective is to study the competing effects of the Kelvin-Helmholtz instability coupled with a stably or unstably stratified fluid system (Rayleigh-Taylor instability) when surface tension is present to regularize the dynamics. Our approach involves the derivation of two-and …

Optimization For Source Localization And Geoacoustic Inversion In Underwater Acoustics, Urmi Ghosh-Dastidar

Dissertations

Matched-field inversion techniques are widely used for source localization and geoacoustic parameter estimation. These inversion methods correlate the received data with modeled data and find the model parameters which provide the maximum correlation. However, when a large number of unknown parameters is involved, many modeled data need to be generated and correlated with the observed data and thus, matched-field inversion can be computationally intensive. An optimization process applied to matched-field inversion is often required to accelerate the inversion process.

In this work, tabu is applied to matched-field inversion for source localization and environmental parameter estimation. Tabu is a global optimization …