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An Approach For Representation Of Organizational Mental Models Using System Dynamics, Jörg-Peter Theissen

Engineering Management & Systems Engineering Theses & Dissertations

The concept of mental models has received much attention within recent years, especially within the context of organizational learning. This research is based on and departs from the Organizational Learning Process as developed by Keating, Robinson, and Clemson (1994). That process, which is based on a verbal representation of mental models, does not call forth the kind of change that is desired in Organizational Learning. This research investigates if mental models can be represented in the form of system dynamics models and inquires if this representation is beneficial to the process of Organizational Learning.

The research was designed as a …

An Urban Education Study: Implementing Problem-Solving Strategies In Mathematics As A Function Of Teacher's Learning Styles, Mary Lou Meinhold Fogarty

Theses and Dissertations in Urban Services - Urban Education

This qualitative research was designed to ascertain the impact of teachers' learning styles on an active teaching program. Using grounded theory procedures, the researcher explored the second-year implementation of Moretti and associates' Problem Solver Program by 67 second- through fifth-grade teachers in order to gain information on the major research question: How effective are teachers with different learning styles in implementing problem-solving strategies in mathematics that require an active teaching style? Three Concerns Based Adoption Model (CBAM) instruments were used in this study. Two quantitative instruments were used: The Stages of Concern (CBAM) to determine the degree of program implementation …

The Influence Of Saprolite Composition Texture And Structure On Groundwater Flow In The Piedmont Province Henry County Virginia, John Thomas Russell

OES Theses and Dissertations

At a 500 acre site in Henry County, Virginia, differences in vertical hydraulic conductivity (K_V) and lateral hydraulic conductivity (K_H) measured in saprolites formed from the Fork Mountain biotite gneiss and the Leatherwood granite reflect the control of the fabric, texture, and structure of the parent rock preserved within the saprolite horizon. Using subsurface data collected from approximately 350 boreholes in conjunction with published information enabled various maps to be generated that identify the spatial relationships between geology and topography and their influence on the nature of the saprolite aquifer.

Measurements of K_H determined from …

Seasonal Composition Of Mesozooplankton In The Pagan River, A Nutrient Enriched Virginia Estuary, Lillian Norman Davis

Biological Sciences Theses & Dissertations

A two year study of the mesozooplankton composition and seasonal distribution was conducted in the Pagan River, a nutrient rich tidal estuary and tributary to the lower James River. The mesozooplankton was dominated by calanoid copepods (80%), with the total zooplankton abundance peaks occurring during spring and fall. The total mean abundance, 3008/m', was somewhat lower than those found by other authors, however the mean abundance at one station approximated those means. Seventy-eight percent of the calanoid copepods were Acartia spp. that were primarily responsible for the fall increase in mesozooplankton abundance. The spring increase was primarily due to increases …

Biofeedback Gait Training Auditory Vs. Visual Techniques, Timothy D. Hiemenz

Electrical & Computer Engineering Theses & Dissertations

Training lower extremity amputees to walk normally is quite a difficult task. Amputees must wear a prosthesis so they can walk at all. This allows them some mobility, but their walking pattern may be unnatural. If their gait is temporally asymmetric, they need to exert more energy to move about. This research was initiated to help lower extremity amputees to walk more efficiently using biofeedback gait training. Two types of feedback were developed and tested to determine which method gave the most understandable feedback, validating its use in a clinical setting.

A normal gait cycle uses the lower limbs to …

The Current Voltage Characteristics Of Electron Beam Controlled Thin Film Diamond Switches, Christopher Anthony Molina

Electrical & Computer Engineering Theses & Dissertations

The dark current of natural diamond thin films and the induced current due to electron-beam irradiation was measured up to a range of 7000Ncm'. The contact material was aluminum, annealed and unannealed. Switching experiments were performed with electron energies ranging from 70keV to 172keV. The switching results obtained are strongly dependent on the biasing polarity, incident electron energy, and whether the contact is blocking or Ohmic in nature. A simple model which takes traps into consideration allows us to explain the various switching responses. The range of electrons which define, in part, the switch mode was measured for one sample …

Defining Locally Shared Memory Constructs For Special Purpose Parallel Architectures, David J. Nielsen

Electrical & Computer Engineering Theses & Dissertations

Locally shared memory systems offer significant advantages over other parallel processing systems for specific classes of problems. Locally shared memory systems tend to be easier to program because explicit passing of messages is not necessary. The goal in defining a locally shared memory system is to allow only a small number of processors access to any single memory. If this goal is met, locally shared memory systems provide an architecture which is relatively simple to implement.

To make shared memory architectures attractive to designers of special purpose parallel architectures, the architectures must be scalable. To be scalable, the number of …

Circulation, Summer 1994, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Summer 1994 issue of CCPO Circulation featuring article "Large Influences From Small Features: Submarine Canyons"

Radiative Interactions In Multi-Dimensional Chemically Reacting Flows Using Monte Carlo Simulations, Jiwen Liu

Mechanical & Aerospace Engineering Theses & Dissertations

The Monte Carlo method (MCM) is applied to analyze radiative heat transfer in nongray gases. The nongray model employed is based on the statistical narrow band model with an exponential-tailed inverse intensity distribution. The amount and transfer of the emitted radiative energy in a finite volume element within a medium are considered in an exact manner. The spectral correlation between transmittances of two different segments of the same path in a medium makes the statistical relationship different from the conventional relationship, which only provides the noncorrelated results for nongray analysis. Two features of the MCM that are different from other …

The Effects Of Athletic Participation On Self-Concept, Daily School Attendance, And Grade Point Average Of Female Seventh-Grade Students In Urban Schools, David L. Olah

Theses and Dissertations in Urban Services - Urban Education

This study examined the effects of athletic participation on self-concept, daily school attendance, and grade point average on 503 seventh grade students in urban middle schools. A 2 x 3 factorial MANOVA analyzed self-concept data to determine differences in self-concept associated with the levels of athletic participation with that of pre- and post-treatment test periods. Tukey's post hoc tests were incorporated when a significant F ratio was demonstrated (p< 0.05). Significant differences were noted in four areas of self-concept as defined by Piers-Harris (1984): (1) intellectual and school status (Tukey, p< 0.05), (2) physical appearance and attributes (Tukey, p< 0.05), (3) anxiety (Tukey, p< 0.05), and (4) popularity (Tukey, p< 0.05). No significant differences were noted in three areas of self-concept: (1) behavior, (2) happiness and satisfaction, and (3) self-concept total.

A 3 x 3 factorial ANOVA demonstrated statistical differences in daily school attendance between female students participating in interscholastic athletics with female students not participating in interscholastic athletics. Daily school attendance …

Rational Cubic B-Spline Interpolation And Its Applications In Computer Aided Geometric Design, Kotien Wu

Mathematics & Statistics Theses & Dissertations

Because of the flexibility that the weights and the control points provide, NURBS have recently become very popular tools for the design of curves and surfaces. If the weights are positive then the NURB will lie in the convex hull of its control points and will not possess singularities. Thus it is desirable to have positive weights.

In utilizing a NURB a designer may desire that it pass through a set of data points {x_i} This interpolation problem is solved by the assigning of weights to each data point. Up to now little has been known regarding the …

Determination Of Pancreatic And Salivary Amylase By Enzyme Immunoassay And Their Prevalence In Hyperamylasemic Patients, Sabdra Borgens Ward

Theses and Dissertations in Biomedical Sciences

Currently, amylase determinations are nonspecific for the organ source and are based entirely on the enzymatic properties of amylase to produce a measurable product or byproduct. The determination of pancreatic amylase is important in the diagnosis of acute pancreatitis. Most commercially available tests for amylase employ the measurement of the change in NADH absorbance at 280 nm or of the p-nitrophenol released from a maltotetrose substrate. These are nonspecific measurements of pancreatic amylase and often necessitate other tests to be run such as a serum lipase.

The two predominant isoenzymes of amylase are pancreatic (p-amylase) and salivary (s-amylase); the most …

Flow Kinematics And Dynamics Of The Gulf Stream From Composite Imagery, Caitlin Patrice Mullen

OES Theses and Dissertations

A unique set of contemporaneous satellite-tracked drifters and five-day composite satellite images of the North Atlantic is studied in order to infer the near-surface flow kinematics and dynamics of the Gulf Stream. Using fractal and spectral analyses, two kinematic models, and a potential vorticity model, detailed comparisons are made between these data sets.

Fractal and spectral analyses show that the data set is not fractal, there is no geographic variability, and there is not a strong fractal scaling link between the drifter trajectories and composite temperature fronts as had been postulated by several investigators. These results indicate considerably more work …

The Effect Of Same-Sex Grouping Versus Mixed-Sex Grouping On Mathematics Achievement And Attitudes Of Academically Gifted Fourth And Fifth Grade Females In The Urban Classroom, Martha J. Tompkins

Theses and Dissertations in Urban Studies

Reports of the neglect of gifted students in America's schools and the inadequate mathematics involvement of females have made educators aware of a crisis in public education. Attitudes and opportunities are believed to be major influences in helping females become more involved with mathematics courses and careers. The research project examined the effect of same-sex groups versus mixed-sex groups on mathematics attitudes and achievement in fourth and fifth grade females in a mathematically gifted pilot program at a magnet center. The experimental study was analyzed with Multivariate Analysis of Variance (MANOVA), Analysis of Variance (ANOVA), Regression Analysis, Post-Hoc tests, and …

A Diffuse Reflectance Infrared Fourier Transform Spectroscopic Investigation Of The Oxidation Of Co On Platinum/Tin(Iv) Oxide-Based Catalysts, Julie Christi Stiltner Patrick

Chemistry & Biochemistry Theses & Dissertations

Platinum/tin(IV) oxide-based catalysts have been developed for the oxidation of carbon monoxide at 55 °C and 1 atmosphere pressure. A diffuse reflectance infrared fourier transform spectroscopic (DRIFTS) investigation of this oxidation has been performed. Four catalyst samples have been subjected to a 5% carbon monoxide pretreatment at 125 °C, helium exposure at 55 °C, bottled air (20% oxygen) exposure at 55 °c, and exposure to a 2:1 stoichiometric mixture of carbon monoxide and oxygen at 55 °C. During the course of these exposures, evidence for the development of two different surface carbon monoxide configurations has been found: one that is …

Some Sampling Designs And Estimation Problems, Hassan Lakkis

Mathematics & Statistics Theses & Dissertations

In the first chapter we review some standard estimators in sampling from a finite population, and some design-based estimators in sampling from a continuous universe.

In concert with the theory initiated by professor Douglas Robson (personal communication) and later presented by Cordy (1993), we consider design-based variance estimation for probability sampling from a continuous and spatially distributed universe. Using this theory in chapter two, the sampling design of one random point from each cell of a translated grid is investigated and the problem of edge effects on estimation is illustrated with examples. Also in chapter four, standard systematic sampling methods …

An Experimental And Analytical Investigation Of The Iosipescu Shear Test For Composite Materials, Barry Stuart Spigel

Mechanical & Aerospace Engineering Theses & Dissertations

Mechanical properties of composite materials under shear loading are difficult to determine. The Iosipescu Shear test, originally proposed for metals, has in recent years been applied to composites. It has the advantages of small specimen size, simple loading and a reasonably uniform shear stress in the test section.

The purpose of this work is to study the validity of the Iosipescu test method for measuring the shear modulus and shear strength of composites. Finite element analyses indicate that optimum specimen geometry and load locations depend upon the degree of orthotropy of the composite. Test results for a quasi-isotropic graphite/epoxy laminate …

Transient Simulations And Modelling Of Semi-Insulating Gaas Photoconductive Switches, Prasun Kumar Raha

Electrical & Computer Engineering Theses & Dissertations

The primary objective of this thesis is to develop a one-dimensional transient simulator for Photoconductive Semiconductor Switches (PCSS) taking into consideration the material characteristics, the internal physical effects, and the external circuit. Simulations have been performed to study the device behavior at different voltage levels for copper-doped silicon-compensated GaAs material, though other materials could easily be simulated by changing the parameters. The model includes hole transport, and the results demonstrate the effect of hole injection, with and without recombination centers. In addition to developing a one-dimensional transient simulator, the role of various physical effects, such as the field-dependence of trapping …

Stress Fields In Composites With A Variable Interphase Under Thermo-Mechanical Loadings, Nianfeng Chen

Mechanical & Aerospace Engineering Theses & Dissertations

An interphase in a composite material has a important role for the composite performance. It influences directly or indirectly the strength, fatigue performance and effective properties of the composite. Recently, interphase has drawn increasing attention in composite mechanics. To the best of our knowledge, however, no one seems to have considered the effect of the variable material prope1ty in the interphase on the stress field in the composite material. In this research, the stress fields are determined in the continuous fiber composite and the particulate composite by using the four concentric circular cylinders model and the four phase spheres model, …

Strong Magnetic Field Effects And Molecular Processes With Applications To White Dwarfs, Phillip C. Stancil

Physics Theses & Dissertations

Radiative transitions of hydrogenlike atoms in external magnetic fields of strength applicable to magnetic white dwarfs, i.e. B < 10³ megagauss, have been investigated for field-free principal quantum numbers n < 6. Finite proton mass corrections are included. Relativistic corrections are also investigated. Transition probabilities are determined using the length, velocity, and acceleration forms of the electric dipole operator. Discrepancies between previous calculations and magnetic white dwarf observations of low-lying boundbound transitions have been studied. New results for high-lying transitions are also obtained.

The transition probability for the hydrogenlike 2s two-photon decay has been investigated and shown to increase substantially with field strength. The computed two-photon spectra show resonances and interference minima. Anomalous Zeeman depolarization features are found in computed two-photon polarization spectra of alkali atoms in laboratory strength magnetic fields. A previously observed fine structure depolarization feature is shown to decay with decreasing field strength.

Benthic Community Responses To Hypoxic Conditions In The Lower Rappahannock River, Virginia, Mary Elaine Smith

Biological Sciences Theses & Dissertations

The effects of seasonal low dissolved oxygen conditions upon benthic macroinvertebrate communities were studied in the lower Rappahannock River, a tributary of the Chesapeake Bay. Benthic communities were sampled during March, June, August, and September 1993 at five equidistant depths (5, 10, 15, 20, and 25 m) extending upwards from the deepwater Virginia Benthic Biological Monitoring Station LE3.4 located in the deep basin just inside the mouth of the Rappahannock River. Infaunal species diversity, richness, biomass, and density were measured along with the vertical depth distribution of organisms within the sediment. Significant sediment differences were found between the shallowest, 5 …

Reproductive Biology Of Chesapeake Bay Black Drum, Pogonias Cromis, With An Assessment Of Fixatives And Stains For Histological Examination Of Teleost Ovaries, Brian K. Wells

Biological Sciences Theses & Dissertations

Based on three years of data collection on the periodicity of the spawning run, the gonadosomatic index (GSI), and gonad histology, the spawning season for Chesapeake Bay black drum was found to be significantly shorter and later compared to populations from Florida and the Gulf of Mexico. The GSI is maximal in early April when black drum first enter the Chesapeake Bay region in contrast to data from Florida where GSI peaks during February and March. I confirm that black drum from the Chesapeake Bay are batch spawners. These results match those found for populations of black drum in the …

Use Of The Genetic Algorithm In Positioning Sacrificial Anodes For Optimum Cathodic Protection, Chi-Cheng Tsao

Mechanical & Aerospace Engineering Theses & Dissertations

A systematic design methodology is developed in this thesis to automatically determine the best locations to place the anodes in order to obtain the maximum cathodic protection. The design methodology numerically solves a design optimization problem which selects the locations to place the anodes to maximize the difference between the minimum current density supplied by sacrificial anodes on the surface of the cathodic materials and its free corrosion current density. The numerical tools used in this design methodology are the finite element analysis and the genetic algorithm. The former analyzes the current density distribution in the field of concern and …

Investigation Of Computational And Spectral Analysis Methods For Aeroacoustic Wave Propagation, Florence Odile Vanel

Mechanical & Aerospace Engineering Theses & Dissertations

Most computational fluid dynamics (CFD) schemes are not adequately accurate for solving aeroacoustics problems, which have wave amplitudes several orders of magnitude smaller yet with frequencies larger than the flow field variations generating the sound. Hence, a computational aeroacoustics (CAA) algorithm should have minimal dispersion and dissipation features. A dispersion relation preserving (DRP) scheme is, therefore, applied to solve the linearized Euler equations in order to simulate the propagation of three types of waves, namely: acoustic, vorticity, and entropy waves. The scheme is derived using an optimization procedure to ensure that the numerical derivatives preserve the wave number and angular …

An Assessment Of Four-Hour Sample Durations Used To Determine Full-Shift Noise Exposures In A Foundry, Vince Marlo Fleming

Community & Environmental Health Theses & Dissertations

Full-shift sampling, usually eight hours, is traditionally performed to assess daily occupational noise exposure. This sampling approach is inefficient, and costly for repeated, long-term exposure evaluations. This study assessed the use of four-hour sample durations and subsequent data analysis to determine daily occupational noise exposures in a foundry. The four-hour sample durations were extracted from full-shift samples and analyzed on their ability to provide valid data for estimating mean daily noise exposure levels without significantly affecting sampling precision or accuracy. Results of this study indicate four-hour sample durations can be used successfully to estimate full-shift noise exposures provided certain criteria …

Circulation, Spring 1994, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Spring 1994 issue of CCPO Circulation featuring article "The MPC Project"

The Speciation Of Dissolved Uranium In Marine Waters, Darrin Kent Mann

OES Theses and Dissertations

Uranium has been used extensively for quantifying geochemical processes in the marine environment. Due to its low concentration, about 3.3 μg/1, some form of preconcentration is required for analysis. The two most widely used pre-concentration schemes are co-precipitation with iron hydroxide, and chelating ion exchange chromatography. These methods were developed by following the behavior of inorganic uranium isotopes and seemed to give identical results. However, when used for trace metal analysis, these methods have been shown to extract different fractions from the same sample. Chelex-100 resin removes only inorganic or weakly bound trace metals from a solution, while the precipitates …

Building A Consensus For The Development Of National Standards In History, Mary Vassilikou Bicouvaris

Theses and Dissertations in Urban Services - Urban Education

This research project examines the process used by the National History Standards Project to build consensus for the development of national standards for teaching history in America's schools.

Since the publication of A Nation At Risk: The Imperative for Educational Reform by the National Commission of Excellence in Education in 1983, the American educational community has been in the grips of a reform movement. The aim of this movement is to examine where we have been and where we are going as a nation and to redefine what we believe in and what we believe is important to teach our …

The Effects Of An Urban Middle School Dropout Prevention Program On The Academic Achievement, Attendance, Attitudes, And Conflict Resolution Skills Of At-Risk Student, Patricia Hawkins Fisher

Theses and Dissertations in Urban Services - Urban Education

The purpose of this study was to determine the effects of an urban middle school dropout prevention program on the academic achievement, attendance, attitudes toward self and school, and conflict resolution skills of potential dropout candidates. The study compared the differences in grade point averages and Iowa Test of Basic Skills scores, percentages of absences, self concept and motivation towards school scores, and the percentage of suspensions of subjects in three middle schools in Portsmouth, Virginia. A review of literature revealed that traditional dropout prevention efforts have addressed the dropout dilemma with varying degrees of success. More recent dropout initiatives …

Methods For The Comparison Of Timing Behavior Applied To The Pink Salmon Fisheries Of Prince William Sound, Alaska, Louis J. Rugolo

OES Theses and Dissertations

Harvest control in salmonid fisheries was examined as a problem in the formulation of regulations which restrict time and area of fishing. An ability to rigorously define and compare the form of the progression of migration across time and between harvest areas was judged fundamental to objective harvest decisions. Identification and evaluation of statistical methods appropriate to the comparison of empirical migratory time densities was performed.

The development of the measure of central tendency (mean date) of the time density as the consistent, unbiased estimator of migratory behavior was given. Practical evidence demonstrated that the mean date was highly resistant …