Digital Commons Network^™

Resolvability In Graphs, Varaporn Saenpholphat

Dissertations

The distance d (u, v ) between two vertices u and v in a connected graph G is the length of a shortest u - v path in G . For an ordered set W = { w1 , w2 , [Special characters omitted.] &cdots; , wk } of vertices in G and a vertex v of G , the code of v with respect to W is the k -vector cW (v ) = (d ( v, w1 ),d (v, w 2 ), [Special characters omitted.] &cdots; , d …

After Turning Points: Evidence Of The Adoption Of Middle School Reforms In The United States 1987-2000., Nancy Barnes Mansberger

Dissertations

The purpose of this study was to explore the adoption by U.S. middle schools of key practices recommended by the 1989 Turning Points report. Three questions were examined: (1) To what extent have the organizational practices identified by research to impact the development of "small learning communities" been adopted by U.S. middle schools? (2) To what extent do the instructional practices of U.S. middle school teachers reflect developmentally responsive or traditional/bureaucratic methods?, and (3) Do the instructional practices of U.S. middle school teachers differ between those who teach in schools with developmentally responsive organizational practices and those who teach in …

A Test Of Factor Analysis As A Validation Procedure For Physician Certification Examinations, Jeffrey D. Greene

Dissertations

Two physician certification examinations from different medical specialties were investigated. The purpose of the study was twofold: 1) to determine the similarities between the factor structure of the examinations and their respective tables of specifications; and 2) to demonstrate the relative efficacy of factor analysis in differentiating the structure between two related but dissimilar domains of information. Specialty A is a homogeneous discipline focused on a relatively narrow concentration of organs, body systems and anatomy. This examination contained 309 items. There were 845 cases available for analysis. Specialty B is a heterogeneous area of specialty concerned with numerous areas of …

Examining The Similarities And Differences In Benefits Of School-To-Work As A Workforce Development Strategy: A Study Of Key Stakeholder Involvement Using A Multiple Case Study Approach, Alton Leon Alford

Dissertations

As we enter the new millennium, there is considerable evidence which indicates that in the 1990's many U.S. business were experiencing rapid growth and expansion resulting from a robust American economy. As a result, business activity in most employment sectors has shown many signs of future growth with projections of continued growth well into the 21st century. This growth in the new economy has resulted in a critical need for highly skilled entrants into the workforce whose working life times will extend toward the mid-twenty-first century (Judy & D'Amico, 1997). With an identified skills shortage looming over many U.S. corporations …

Adaptive Ds-Cdma Multiuser Detection For Time Variant Frequency Selective Rayleigh Fading Channel, Xin Tang

Dissertations

The current digital wireless mobile system such as IS-95, which is based on direct sequence Code Division Multiple Access (DS-CDMA) technology, will not be able to meet the growing demands for multimedia service due to low information exchanging rate. Its capacity is also limited by multiple accessed interference (MAI) signals.

This work focuses on the development of adaptive algorithms for multiuser detection (MUD) and interference suppression for wideband direct sequence code division multiple access (DS-CDMA) systems over time-variant frequency selective fading channels. In addition, channel acquisition and delay estimation techniques are developed to combat the uncertainty introduced by the wireless …

Em-Based Iterative Channel Estimation And Sequence Detection For Space-Time Coded Modulation, Zbigniew Baranski

Dissertations

Reliable detection of signals transmitted over a wireless communication channel requires knowledge of the channel estimate. In this work, the application of expectationmaximization (EM) algorithm to estimation of unknown channel and detection of space-time coded modulation (STCM) signals is investigated. An STCM communication system is presented which includes symbol interleaving at the transmitter and iterative EM-based soft-output decoding at the receiver. The channel and signal model are introduced with a quasi-static and time-varying Rayleigh fading channels considered to evaluate the performance of the communication system. Performance of the system employing Kalman filter with per-survivor processing to do the channel estimation …

Resonances Of Periodic Metal-Dielectric Structures At The Infrared Wavelength Region, Oren Sternberg

Dissertations

Metal meshes have been used as reflectors in radar receivers for wavelength much longer than the periodic constant of the conducting wires and as optical reflectors in a FabryPerot in the far infrared. Cross shaped metal meshes can be used as band pass filters but the design theory and near field properties have not been known.

Transmittance of thin, single-layer and multiplayer metal meshes has been investigated using Micro-Strips, yielding numerical solutions of Maxwell's equations. The near field effect was studied for two alignment configurations of cross shaped metal meshes, both free standing and with dielectrics, and transmission line theory …

Thermal Treatment Of Organic Contaminated Solids And Waste : Experiment, Model And Mass Balance, Hsien-Tsung Chern

Dissertations

A number of processes can be used to remediate contaminated soils. The thermal technologies for remediation of contaminated soils are summarized in this study. Each of these treatment process along with their system components are identified and described. Waste applicability is included for each treatment technology. A detailed list of feasible treatment processes is presented with descriptions of site demonstration results to aid ill selection of a given process. Technology status is summarized to provide current information on the processes.

Energy components are discussed for cost requirement and safety considerations in thermal treatment applications. It is determined that the heat …

A Microfabricated Microconcentrator For Sensors And Chromatography, Minhee Kim

Dissertations

The detection and quantitative measurement of trace components is a challenging task. The key component in such an instrument is the concentration step where the analytes are accumulated before the analysis. In this research, simple and inexpensive processes for the microfabrication of microconcentrator that can be used with sensors and as an injector in GC were developed. Analytes are selectively concentrated in the microconcentrator. Rapid electrical heating of the microconcentrator releases the adsorbed species as a 66 concentration pulse", which serves as an injection for the detection system. The relatively small size of the microconcentrator allows it to be heated …

Development Of Membrane Extraction Techniques For Water Quality Analysis, Dawen Kou

Dissertations

This research involved the development of membrane-based analytical techniques as applied to various aspects of water quality analysis. Gas injection membrane extraction was developed for fast on-line analysis of volatile organic compounds in water. Gas injection of aqueous samples increased the speed of membrane extraction. The aqueous boundary layer effects encountered during water elution was reduced. Axial mixing of the sample with a gaseous eluent was minimal, and this eliminated the tailing in the permeation profiles. The overall effect was significantly faster penneation. The overall diffusion coefficient during gas injection was found to be seven times the value during aqueous …

Catalytic Reduction Of Nitric Oxide By Solid Carbonaceous Material Under Lean Condition, Shan Xiao

Dissertations

The reactions of O₂, NO_x and soot from Diesel exhaust over Cu containing catalysts can significantly reduce soot and NO_x emissions while producing N₂ and CO₂. The author has evaluated the performance of Cu ion exchanged ZSM-5 and Cu adsorbed on Granulated Activated Carbon (Cu-GAC) using GAC as a surrogate for soot in a packed bed reactor. CO, formed primarily by the oxidation of GAC with O₂, appears to be a stable intermediate in the reduction of NO. With experimental parameters chosen to simulate Diesel exhaust conditions, Cu-GAC is much more …

Knowledge Discovery And Modeling In Genomic Databases, Michael M. Yin

Dissertations

This dissertation research is targeted toward developing effective and accurate methods for identifying gene structures in the genomes of high eukaryotes, such as vertebrate organisms. Several effective hidden Markov models (HMMs) are developed to represent the consensus and degeneracy features of the functional sites including protein-translation start sites, mRNA splicing junction donor and acceptor sites in vertebrate genes. The HMM system based on the developed models is fully trained using an expectation maximization (EM) algorithm and the system performance is evaluated using a 10-way cross-validation method. Experimental results show that the proposed HMM system achieves high sensitivity and specificity in …

Electron Correlation Leading To Double-K-Shell Vacancy Production In Li-Like Ions Colliding With Helium, Ali Sami Alnaser

Dissertations

Single and double K-shell vacancies in Li-like ions colliding with neutral helium target have been investigated using high-resolution Auger projectile spectroscopy. Be⁺, B²⁺, C³⁺, and O⁵⁺ Li-like ions were produced and accelerated to intermediate-to-high collision velocities where perturbative models are expected to be valid, using the Tandem Van de Graaff accelerator at Western Michigan University. Double-K-shell vacancies in atomic systems or so-called “ hollow ions” can be induced by different mechanism in ion-atom collisions. For intermediate-to-high velocity collisions where the collision time is small, the projectile ion can interact with only one of …

Numerical Studies Of Transition For Flows Around Multi-Element Airfoils, Fengjun Liu

Dissertations

The transition of flows around a multi-element airfoil has been numerically studied using RANS with a k - e two-equation transition model, LST and DNS. The transition model uses an effective eddy-viscosity by coupling an intermittence-like correction to a turbulence eddy-viscosity that can be obtained via solving a parent k - e turbulence model. The transition model is truly predictive in that it is able to predict transition onset locations without having to specify prior knowledge of the targeted transition process. The predicted transition onset locations for all the cases studied were compared with the measured data. The results suggest …

An Analysis Of Student Progress In Beginning Flight Training: Performance Prediction, Performance Measurement, And Performance Improvement, Ryan Olson

Dissertations

The current project was designed to explore potential strategies for reducing the risk of accidents and incidents with beginning flight students (V = 28) by: (a) evaluating the CogScreen™ Aeromedical Edition (CogScreen-AE) test as a predictor of performance, (b) investigating patterns in student performance using expanded data collection procedures, including more extensive measurement of landings, and (c) evaluating the effects of early supplemental training on a personal computer-based aviation training device (PCATD). The experimental manipulation employed a matched pairs research design and exposed a treatment group (rt = 14) to six trials of “skill pattern” practice on a PCATD, with …

A Study Of Expert Problem-Solving In Qualitative Organic Analysis Using A Computer Simulation, Keith A. Schramm

Dissertations

A qualitative case study of eight doctoral level organic chemists from academia (6) and industry (2) solved eleven qualitative organic analysis problems using the Identification of Organic Compounds* software computer simulation. Think-aloud protocols were analyzed for content knowledge and strategic knowledge to account for expert performance. Each of the eleven qualitative organic analysis problems included a variety of functional groups and structures and was solved in a computer-simulated environment to allow for extensive problem-solving by the experts and to evaluate the simulation’s ability to model the problem-solving environment The data provided consisted of the typical instrumentation available to university undergraduate …

Visualization Methods: A Comparative Study Of New, Traditional And Robust Procedures, Kimberly Crimin

Dissertations

Two major goals in discriminant analysis are discrimination and classification. In discrimination, the goal is to describe graphically (visualization) different features of several known groups. In classification, the goal is to allocate unknown observations to one of several known groups. We have developed new visualization procedures based on traditional estimating procedures and also on robust estimating procedures. We have further developed robust classification procedures. We propose several robust classification procedures based on coordinatewise and affine equivariant, rank-based robust estimates. Empirical studies are performed over many different error distributions. These studies result in empirical efficiencies of the robust and traditional procedures. …

A New Type Of Particle Detector For Nuclear Scattering Experiments, Philip Ugorowski

Dissertations

A new detector was needed for counting recoil protons resulting from proton-proton (pp) elastic scattering during pion production experiments by the Polarized Internal Target Experiments (PINTEX) group at Indiana University Cyclotron Facility (IUCF). The previous silicon detectors were only usable forincoming protons up to 9 MeV, and a stopping power of at least 40 MeV was needed. In addition, the detector had to operate in nanotorr vacuum, and near strong varying magnetic fields, ruling out standard organic plastic scintillators and photomultiplier tubes. We needed to find the most suitable inorganic scintillator and another method of detecting the photons produced when …

Separable Preference Orders, Jonathan K. Hodge

Dissertations

Whenever a decision-maker must express simultaneously his or her preferences on several possibly related issues, the existence of interdependence among these preferences can lead to collective decisions that are unsatisfactory or even paradoxical. Intuitively, an individual’s preferences are said to be separable on a subset of issues if they do not depend on the choice of alternatives for issues outside the subset. Here we explore from a mathematical standpoint the properties of separable and nonseparable preference orders. We begin by formulating a general model of multidimensional preferences and we formally introduce the notions of separability and noninfluentiality. We study the …

Ideology Or Insanity? Media Presentation Of Ted Kaczynski And Tim Mcveigh, Matthew P. Sheptoski

Dissertations

This dissertation explores mainstream media presentation of two convicted murderers: Theodore J. Kaczynski, otherwise known as "The Unabomber," and Timothy J. McVeigh, found guilty of the 1995 destruction of the Murrah Federal Building in Oklahoma City, Oklahoma. More specifically, I analyze The New York Times's and Time's presentation of these two actors in order to assess whether their acts were attributed to political and ideological motivation or psychological abnormality and mental illness. Quantitative and qualitative findings indicate that Kaczynski's crimes were more likely to be attributed to psychological abnormality and mental illness, while McVeigh's crimes were more likely to be …

The Relationship Between Financial Aid And Freshman Persistance At A Midwestern Liberal Arts College, Jack Phillip Powell

Dissertations

College student persistence has been one o f the most important topics discussed in higher education over the last 25 years. The consequences of student attrition from our colleges and universities are immense for the individual student and institutions alike. One of the purposes of student financial aid is to promote student persistence. The need for empirical research to assess whether financial aid is accomplishing this vital purpose is critical Research is particularly important given the significant shifts in policy brought on by the 1992 Reauthorization of the Higher Education Act. This study addressed two research questions. The first deals …

Local Symmetries Of Symmetrical Cayley Maps, Paula T. Smith

Dissertations

Graphs, groups, and surfaces are all subjects of study in topological graph theory, using techniques and principles from the disciplines of graph theory, algebra, and topology. A Cayley graph provides a graphical representation of a finite group and a fixed generating set for the group; a Cayley map is a two-cell imbedding into a surface of a Cayley graph such that labeled outward-directed darts occur in the same sequence at each vertex. A dart is a directed edge. In this work, we generalize Cayley maps to allow two-cell imbeddings of graphs with loops and multiple edges.

In this thesis, we …

Classroom Questioning Strategies As Indicators Of Inquiry Based Science Instruction, Linda Hale Goossen

Dissertations

Inquiry teaching often rests upon the assumption that through the use of questioning and response strategies, teachers can stimulate students to actively construct knowledge. Based on this hypothesis, middle-school science lessons were observed and questioning and response strategies were identified that are related to inquiry-based instruction.

Twenty-four science lessons were observed, videotaped, and ranked by inquiry characteristics other than questioning strategy. The video and audio portions of the recordings were analyzed to determine the student and teacher’s questioning and response strategies in each classroom. These strategies were then compared to teaching style, along a continuum from traditional to inquiry, to …

Nonlinear Regression Based On Ranks, Asheber Abebe

Dissertations

This study presents robust methods for estimating parameters of nonlinear regression models. The proposed methods obtain estimates by minimizing rankbased dispersions instead of the Euclidean norm. We focus on the Wilcoxon and generalized signed-rank dispersion functions. Asymptotic properties of the estimators are established under mild regularity conditions similar to those used in least squares and least absolute deviations estimation. The study also shows that by considering the generalized signed-rank dispersion we obtain a class of estimators that encompasses most of the existing popular nonlinear regression estimators. As in linear models, these rank-based procedures provide estimators that are highly efficient. This …

The Impact Of Systematically Varying The Duration Of Breath Samples During Infrared-Based Alcohol Breath Testing, Chris C. Clatterbuck

Dissertations

The present study set out to investigate the reliability and performance of the BAC DataMaster®, an infrared-based alcohol breath testing instrument. The focus of this study was to determine: (a) the impact of varying breath sample duration during testing, (b) if Blood Alcohol Concentration (BAC) levels produced by the DataMaster® (BAC_DM) are significantly different from BAC levels produced by analysis of whole blood (BAC_WB), and (c) if the relationship between BAC_DM estimates and BAC_WB is influenced by the amount of alcohol an examinee has ingested. Each of 27 participants was randomly assigned to one …

Bi-Axially Loaded Slender Reinforced Concrete Columns Subjected To Sustained Loads, Song Gu

Dissertations

A generalized analytical approach is presented in this research to predict the behavior both of slender and short reinforced concrete columns under sustained biaxial eccentric load.

The present analysis proposes equations established at a cross section of a reinforced concrete column by combining force equilibrium, constitutive law, and compatibility conditions. The strain and curvature of each section and the deflection of the column can then be obtained and resolved.

The established creep computation models, recommended separately by American Concrete Institute (ACI) 209R-92 and the Comite' Euro-International du Be'ton (CEB)-FIP 1990 Model Code have been used to calculate creep and shrinkage …

Nonlinear Interfacial Stability Of Core-Annular Film Flows In The Presence Of Surfactants, Said A. Kas-Danouche

Dissertations

This work is an analytical and computational study of the nonlinear interfacial instabilities found in core-annular flows in the presence of surfactants. Core-annular flows arise when two immiscible fluids (for example water and oil) are caused to flow in a pipe under the action of ail axial pressure gradient. In one typical type of flow regime, the fluids arrange themselves so that the less viscous (e.g. water) lies in the region of high shear near the pipe wall, with the more viscous fluid occupying the core region. Tech nologically, this arrangement provides an advantage since the highly viscous fluid is …

The Development Of H Homogeneous Nucleation Rate Model For Thermoplastic Foams Based On A Molecular Partition Function And Fickian Diffusion, Ronald G. Gabbard

Dissertations

An improved homogeneous nucleation rate model for thermoplastic foams has been developed. This model does not rely on experimentally determined parameters and only uses pure component physical property data and a binary diffusion coefficient. This model, like those derived from classical nucleation theory, is made up of two parts, one that determines the size of the energy barrier in the nucleation process and one that estimates the forward rate of the process. A statistical-mechanical approach was used to create an energy term that is based on a molecular partition function. In this approach, the bulk phase (polymer and blowing, agent …

Temporal Synchronization Of Ca1 Pyramidal Cells By High-Frequency, Depressing Inhibition, In The Presence Of Intracellular Noise, Stephen A. Kunec

Dissertations

The Sharp Wave-associated Ripple is a high-frequency, extracellular recording observed in the rat hippocampus during periods of immobility. During the ripple, pyramidal cells synchronize over a short period of time despite the fact that these cells have sparse recurrent connections. Additionally, the timing of synchronized pyramidal cell spiking may be critical for encoding information that is passed on to post-hippocampal targets. Both the synchronization and precision of pyramidal cells is believed to be coordinated by inhibition provided by a vast array of interneurons. This dissertation proposes a minimal model consisting of a single interneuron which synapses onto a network of …

Experimental And Theoretical Study Of An Integrated Silicon Mach-Zehnder Interferometer For Chemical Sensing Applications, Yew Fong Hor

Dissertations

This thesis involves the design, fabrication and characterization of an integrated optical waveguide sensor. Prior to fabrication, design parameters of the waveguide need to be determined and optimized. The waveguide parameters such as waveguide dimension and the refractive index of the core and cladding are obtained from the single-mode cutoff frequency calculated using either analytical or numerical methods. In this thesis, details of analytical calculations to determine the cutoff frequency in terms of the waveguide parameters will be presented. The method discussed here is Marcatili's approximation. The purpose is to solve the scalar wave equation derived from Maxwell's equations because …