Digital Commons Network^™

A Model Of Electronic Warfare Systems Acquisition And Engineering For Saudi Arabia, Negaa M. Albegami

Doctoral Dissertations

"A major activity within the systems engineering process is the requirements definition and analysis phase. In technical systems, planning this phase looks too technical for top management and too broad for the engineers specialized in narrow technical fields. This categorization (too technical/too broad) represents a gap between top management and specialized engineering. In Saudi Arabia, such a gap is believed to be very wide.

The main objective of this research is to find a way to narrow this gap between management and engineering when planning government systems, especially in electronic warfare (EW) systems. A solution in this effort is to …

Genetic Algorithms With 3-Parent Crossover, L. Vincent Edmondson

Doctoral Dissertations

"A new genetic algorithm which uses a 3-parent uniform crossover operator is developed and analyzed. Uniform crossover operators are shown to be based on the premise that all bit-level genetic information should be passed from parents to children. The 3-parent uniform crossover operator is shown to adhere to this premise. The 3-parent uniform crossover operator is shown to be better than the 2-parent uniform crossover operator on the De Jong test functions.

Two new genetic algorithms which use 3-parent traditional crossover operators are developed and analyzed. The first uses a strategy of randomly selecting 3 of the 6 children resulting …

Galvanic Stripping Of Fe⁺³ And Pb⁺² Ions And Dissolution Of Metallic Fe, Zn, Pb And Cd Using Di(2-Ethylhexyl)Phosphoric Acid, Luis Miguel Chia Aquije

Doctoral Dissertations

"Two systems were evaluated using the principles of the galvanic stripping process. One of them, the removal of Pb⁺² ions from di-2(ethylhexyl) phosphoric acid (D2EHPA) was performed using metallic zinc. The other, the removal of Fe⁺³ ions from D2EHPA used metallic iron as reductant and was performed simultaneously with the organic phase using a slightly acidic aqueous solution of hydrochloric acid. In addition, the dissolution of metallic zinc, iron, lead, and cadmium in D2EHPA was studied in order to better understand the anodic step in the mechanism of the galvanic stripping process.

Increased temperature was found to dramatically …

Self-Diffusion Studies In Polymer-Solvent Systems By Pulsed-Gradient Spin-Echo Nuclear Magnetic Resonance, R. Allen Waggoner

Doctoral Dissertations

"Pulsed gradient NMR techniques have been used to study self-diffusion in polymer solutions. The systems studied include toluene, cyclohexane, ethylbenzene, chloroform, t-butyl acetate, and methyl ethyl ketone in polystyrene; methyl methacrylate in poly(methyl methacrylate); poly(ethylene oxide) in water; and water in biological tissue. The polymer diffusion data are evaluated in terms of scaling theory as they relate to the scaling of the polymer diffusion coefficient with molecular weight. The solvent diffusion data are evaluated with kinetic and free-volume theories. In addition a relatively simple dependence of diffusion coefficient on polymer volume fraction is derived from free-volume theory. The solvent diffusion …

Arene-Alkene Meta Photocycloadditions And Conjugated Enyne Photorearrangements, Manli Zheng

Doctoral Dissertations

The new advances and synthetic potential of arene-alkene meta photocycloadditions, with the goal of rapid approach to polycyclic molecules, are described. Vinyl cyclohexanecarboxylate has been found to be an efficient alkene moiety to improve the reaction efficiency by reducing formation of polymers during irradiation. Exploration of asymmetric meta photocycloaddition, via chiral auxiliaries, resulted in partial asymmetric induction. Fluorescence studies have led to a better understanding of the reaction mechanism. Intramolecular isotope effect results on meta photocycloaddition remain unexplained.

Conjugated enynes undergo a singlet photorearrangement, resulting in a pseudodegenerate rearrangement. The synthesis of starting materials, characterization of products, studies of the …

A Transmission Electron Microscopy Study Of Defect Generation And Microstructure Development In Ultrasonic Wire Bonding, Nikhil Mohan Murdeshwar

Doctoral Dissertations

Ultrasonic wire bonding is widely used in the electronic industry to connect semiconductor chips to packages. Even though the popularity of the technique has increased in recent times, questions remain about the bonding mechanism, and factors affecting bondability and reliability. In this thesis, answers were provided to many of these questions using TEM to examine bonded cross section and plan view specimens.

A detailed investigation of the Al wire and substrate showed dynamically annealed well recovered grains while microstructural observations of other substrates revealed wide varieties of response mechanisms. For example, Ni formed a dislocation cell structure, Cu formed a …

Characterizing And Improving The Fault Tolerance Of Artificial Neural Networks, Bruce Edmond Segee

Doctoral Dissertations

Artificial neural networks are networks of very simple processing elements based on an approximate model of a biological neuron. It is widely believed that because biological neural networks are tolerant of the loss of individual neurons and because there is a strong analogy between biological neural networks and artificial neural networks, then artificial neural networks must also be inherently fault tolerant. This is, unfortunately, simply not true.

Results reported in this dissertation show that in the task of function approximation the multilayer perceptron is very intolerant of faults to the extent that the loss of a single network parameter can …

Money, Income And Causality: An Open Economy Reexamination, El-Hachemi Aliouche

Doctoral Dissertations

The positive relationship between the rate of growth of the money supply and the rate of growth of aggregate income is a widely accepted principle in macroeconomics. However, the direction of the causality between these two variables has been an enduring subject of controversy.

Recent developments in time series analysis, particularly those relating to the concepts of integration and cointegration, and the stationary nature of economic time series, promise to help settle the debate on the statistical relationship between money supply growth and income growth. Most of the recent work on this issue, however, has been confined to a closed …

Techniques For Enumerating Protozoa In Saturated Subsurface Sediments, Amoret L. Bunn

Doctoral Dissertations

Three techniques were investigated for the enumeration of small (2-5 $\mu$m in diameter) flagellates and amoebae in sediments collected within and outside of a wastewater contaminated ground water plume at the U.S. Geological Survey Toxic Substances Hydrology Research site, located on Cape Cod, MA. An epifluorescent direct count technique was developed to enumerate DAPI stained protozoa on polycarbonate membrane filters. These estimates were compared to the those from the Darbyshire liquid media MPN and Singh solid media MPN techniques. In Fall 1991, sediment samples were collected to investigated the variability of the hold time of cores, total and encysted protozoan …

Traces: Modeling The Teaching Consultant In A Problem-Solving Domain, Brian Leigh Johnson

Doctoral Dissertations

A model of a teaching consultant is presented. The teaching consultant, an extension of the concept of a computer coach, is concerned with filling gaps in a student's knowledge base relative to a specific application. The student model used by the consultant is stored in the form of a prerequisite network, which maintains nodes of information that are connected so that prerequisite information may be readily accessed. The Teaching Consultant Model is being used as the basis for an intelligent tutoring system serving as a programming consultant for novice programmers.

Polymer Substrates For Fiber-Optic Chemical Sensors, Amy Elizabeth Straub

Doctoral Dissertations

The primary goal of this research was to examine chemical and mechanical properties of polymers designed for a fiber optic chemical sensor based on polymer swelling. A second goal of this research was to develop a temperature sensor that could be used with other fiber optic chemical sensors.

Fiber optic chemical sensors have the capability for remote use, accuracy, sensitivity, selectivity, and ruggedness. Fiber optic sensors based on polymer swelling exploit the rugged features of polymers and fiber optic communications technology for use in remote sensing. A crosslinked polymer changes size in the presence of an analyte. As the polymer …

A Simulation Study Of Bipedal Walking Robots: Modeling, Walking Algorithms, And Neural Network Control, Paul Walker Latham

Doctoral Dissertations

The purpose of this thesis is to develop walking algorithms for use with mechanical bipeds. This thesis is comprised of three parts. A two dimensional biped simulator, called WALK, is developed. This simulator is designed to facilitate the evaluation of bipedal walking algorithms. Then, a two dimensional walking algorithm is developed using a simple inverted pendulum model. This algorithm is shown to provide for stable walking using the WALK simulator system. A neurocomputer adaptive controller that is based on the CMAC architecture is added to the inverted pendulum model. The adaptive walking algorithm is not only stable, but provides for …

Corrosion Protection Of Metals By Poly(3-Methylthiophene) Coatings, Shouxian Ren

Doctoral Dissertations

Electrochemically prepared poly(3-methylthiophene) (P3MT) films were used as conductive polymer coatings to poise a substrate metal in the passive potential range in corrosive media. To firmly adhere P3MT coatings onto substrate metals, different methods were developed for each metal; stainless steel (430SS), titanium (TiGr2) and carbon steel (C1010). The samples were either pretreated by anodization in phosphate solution to form a uniform porous surface or pitted by chloride ions simultaneously with the formation of an adhesive thin film. Coatings were characterized for various galvanostatic electropolymerization conditions on both platinum and phosphated 430SS (Ph430SS) rotating disk electrodes (RDEs). Both applied current …

A Nonlinear Hybrid And Vr Stepping Motor Analysis Via An Integrated Finite Element And Lumped Parameter Modeling Technique, Steven Roger Huard

Doctoral Dissertations

The work involves the magnetic modeling of a variable reluctance and a hybrid stepping motor. The model combines two traditional methods for creating a magnetic model. Nonlinear two dimensional finite element analysis is combined with nonlinear lumped element modeling to create a three dimension lumped model. The two dimensional finite element analysis is used to numerically calculate the effective reluctance function of the motor tooth region. After the finite element analysis is completed, a two terminal tooth region reluctance element that is a function of both rotor angle and tooth region flux density results. The two terminal lumped element is …

Performance Of Concrete Beams And Slabs Reinforced With Frp Grids, Edwin Robert Schmeckpeper

Doctoral Dissertations

The objective of this dissertation was to evaluate the suitability of Fiber Reinforced Plastic (FRP) grids for use as a structural reinforcement in concrete structures such as highway bridge decks. The work concentrated on determining the mechanical properties of FRP materials, testing the flexural behavior and servicability of concrete beams and slabs reinforced with FRP grids, and determining splice and development length requirements for FRP grids. Design recommendations concerning failure mode, deflections, anchorage requirements were developed.

The results from the flexural tests on FRP reinforced concrete beams, with reinforcing ratios ranging from 0.3% to 2.2%, showed that the failure mode, …

A Neural Network-Based Trajectory Planner For Redundant Systems Using Direct Inverse Modeling, Franklin J. Rudolph

Doctoral Dissertations

Redundant (i.e., under-determined) systems can not be trained effectively using direct inverse modeling with supervised learning, for reasons well out-lined by Michael Jordan at MIT. There is a "loop-hole", however, in Jordan's preconditions, which seems to allow just such an architecture. A robot path planner implementing a cerebellar inspired "habituation" paradigm with such an architecture will be introduced. The system, called ARTFORMS, for "Adaptive Redundant Trajectory Formation System" uses on-line training of multiple CMACS. CMACs are locally generalizing networks, and have an a priori deterministic geometric input space mapping. These properties together with on-line learning and rapid convergence satisfy the …

Transition From Laminar To Turbulent Flow Around An Airfoil, Chang-Ren Chen

Doctoral Dissertations

"A computational fluid dynamics (CFD) code has been developed for two-dimensional incompressible turbulent flows and employed to solve the Navier Stokes equations around an airfoil of arbitrary shape. A low-Reynolds-number k — e turbulence model including curvature effect was used to consider the gain and loss of turbulent kinetic energy. To include laminar sublayer into the computational domain, a multi-layer grid and a cubic-slpine grid were introduced through a conservative form of coordinate transformation. The flow structure varies with the Reynolds numbers. For an airfoil at low Reynolds numbers (below ten thousand), distinct vortex shedding patterns can be found in …

Use Of The 9-Arm Self-Boring Pressure Meter To Measure Horizontal In Situ Stress, Stress Anisotropy, And Stress-Strain Behavior In Soft Clay, R Craig Findlay

Doctoral Dissertations

Self-boring pressuremeter (SBPM) tests were conducted at Interstate I-95 in Portsmouth, New Hampshire and Hamilton Air Force Base in Novato, California, in clays of low and high plasticity, respectively. Both sites were subjects of significant previous research.

Field testing, conducted at and away from the toe of an existing highway embankment, indicated that the SBPM is capable of measuring horizontal stress changes and stress anisotropy when stress differences are more significant than the measurement error of the test equipment and error due to insertion disturbance effects. Finite element modeling was used to assess the embankment stress effects as a basis …

The Special Artist In American Culture: A Biography Of Frank Hamilton Taylor (1846-1927), Nancy Louise Gustke

Doctoral Dissertations

As a Special Artist (newspaper illustrator) for papers such as the New York Daily Graphic and Harper's Weekly, author and illustrator of numerous guidebooks, and astute recorder of Philadelphia, Frank Hamilton Taylor left a unique visual and written record of late nineteenth, early twentieth century American life. His work provided the growing, increasingly literate urban middle class with information about their country from the excitement of the Centennial Exposition to the tragedy of lives lost at sea. In addition, Taylor's documentation of leisure pursuits, particularly in the Thousand Islands area of New York, helped define what constituted recreation for the …

An Improved Multi-Dimensional Cmac Neural Network: Receptive Field Function And Placement, Pak-Cheung Edgar An

Doctoral Dissertations

The standard CMAC has been shown to have fast learning computation as a result of modular receptive field placement, rectangular receptive field shape and a simple weight adaptation algorithm. The standard CMAC, however, suffers from slow convergence at some critical frequency due to the rectangular receptive field shape. A linearly-tapered field, which requires a uniform placement, was used in this research. The receptive field placement of the standard CMAC becomes less uniform locally for a larger receptive field width. This dissertation suggests a new field placement which is more uniform without extra computation. Results show that the slow convergence at …

Semistate Systems And The Continuation Method, Barbara Dziurla-Rucinska

Doctoral Dissertations

This thesis stems from and continues the research of the author and R. Newcomb on semistate theory initiated under the joint Polish-American Program on Active Microelectronic Systems. The main theme is the development of design and analysis techniques through semistate theory, especially for systems containing hysteresis. The use of hysteresis can lead to simplified realizations, for example replacing second order systems by first order ones. Since hysteresis can often be conveniently realized by active electronic components it holds considerable promise for future integrated circuits. However the multivalued nature of hysteresis precludes the use of standard methodologies, such as that of …

Local Heat Transfer To Surfaces Immersed In The Freeboard Region Of A Fluidized Bed, Kun-Yung Tsai

Doctoral Dissertations

This work describes the local heat transfer in the freeboard region of a fluidized bed. Plate surface to particle suspension heat transfer coefficients in the freeboard of a fluidized bed (30 cm i.d.) have been measured by a newly designed miniature heating plate. Four types of plate orientations have been employed to investigate the directional effect of gas-solids flow to plate surface on the heat transfer rate. Local solids concentrations in the freeboard were also obtained by a nozzle-type sampling probe.

Results indicate that the heat transfer coefficient varies with axial and radial plate location, plate orientation, and gas velocities. …

Evaluation Of A Single Artery-Single Junction Model For Detecting Atherosclerotic Plaques From Blood Pressure Waveforms, Donna Lou Lizotte

Doctoral Dissertations

A single artery-single junction model is evaluated independently and relative to existing models to determine if it can provide additional or better information for detecting the presence of atherosclerotic plaques from blood pressure or flow waveforms. The effects of a single stenosis on the arterial pressure pulse are assessed. A 30 cm segment of aorta without branches is modeled with a stenosis of varying parameters located 15 cm from the heart. The aortic pressure pulse serves as input. The effects of the stenosis on the reflected and transmitted peak pressures are analyzed as well as the harmonic amplitudes of the …

Interactive, User-Directed, Computer-Assisted Hplc Methods Development, Fang-Fang Qi

Doctoral Dissertations

An interactive, computer-assisted approach for determining multi-segment gradient elution profiles for High Performance Liquid Chromatography (HPLC) is presented. The approach is based on determining the gradient segment necessary to elute each solute at a user specified retention time. There are five main functions of this approach: (1) To inform the user of the possible retention time ranges for the solute that is going to be eluted for each elution step under both isocratic and gradient elution conditions; (2) To determine the required elution conditions, based on the user's desired retention times and the gradient elution shape; (3) To provide the …

Models Of Macro-Scale Hydrology For Use In Global Change Research: Tests On Two Tropical River Systems, Charles Joseph Vorosmarty

Doctoral Dissertations

The subject of this dissertation is the terrestrial water cycle and development of tools to study the issue of global hydrologic change. A rationale is developed to study the water cycle at regional and continental scales using macro-scale hydrology models coupled to Geographic Information Systems (GIS). A linked Water Balance/Water Transport Model (WBM/WTM) was constructed and tested as part of this research. The model was applied to two tropical river systems, the Amazon River in South America and the Zambezi River in southern Africa.

The WBM/WTM is a distributed parameter model, operating at 0.5$\sp\circ$(latitude x longitude) spatial scale and with …

Toughening Mechanisms In Weak Matrix Ceramic Composites, Jowoong Ha

Doctoral Dissertations

"Tough behavior of ceramic matrix composites is closely related to the weak interface between fiber and matrix. The weak interfaces in composites have been provided by reducing the chemical bonding and the residual thermal stresses between constituents. A new way to introduce the weak interface by induced porosity or damaged zones, so called porosity toughening or damage toughening respectively, was proposed in this study to provide the rationale for guiding development of oxide/oxide composites. The existence of porosity toughening was examined by qualitative theoretical consideration and experiments. Porous oxide/oxide composites were fabricated using alumino-silicate fibers (Nextel 440) and magnesium alumino-silicate …

Toward The Development Of Decision Support Tools To Manage The Catis Project Life Cycle, Steven Wayne Mccrary

Doctoral Dissertations

"The American Public Works Administration (1987) states that communities' infrastructures are in need of repair and better management and recommends CATIS (Computer-Assisted Terraspatial Information Systems) as an excellent tool to assist in that endeavor. Small communities have several voids that CATIS technology can fill. This research reports on a life-cycle approach to CATIS adoption that will help small communities to better manage their infrastructure.

It is important for small communities to become aware of the types of systems available and what each system can do. This study presents a straightforward, understandable discussion of CATIS technologies, features, and applications. Justifying the …

Changing Energy Futures: A Systems Approach To The Adoption Of Energy Alternatives In New Hampshire, Mark Edward Diffenderfer

Doctoral Dissertations

In an attempt to develop a comprehensive approach to the study of the adoption of energy systems, this dissertation first critically examines a variety of approaches to this phenomenon, including market models of adoption, the adoption of innovations literature, and the social psychology of attitudes and behavior. Market models are seen as generally reductionistic and the argument is made that they fail to take into consideration a variety of non-cost considerations. The assumption here is that while price considerations play a role in this process, decisions are also affected by values and attitudes which are not directly incorporated into market …

Development And Application Of Artificial Intelligence Strategies To Solve Infrared Spectroscopic Problems, Barry J. Wythoff

Doctoral Dissertations

The ever-increasing power of modern infrared instrumentation, coupled with the decreasing number of experienced spectroscopists has created an imbalance between information generation and interpretation capabilities. At the same time, digital computers are being developed which continue to grow in storage and processing capabilities, and shrink in cost. Clearly, the computer may serve as a valuable tool to aid the analytical chemist in interpreting spectroscopic information. This dissertation deals with the development of new approaches to exploiting computer technology to interpret infrared spectroscopic data.

A large existing expert system for functional group analysis, PAIRS, has been modified to transfer the maximum …

The Analysis And Design Of Brushless Dc Motors, Steven Ronald Prina

Doctoral Dissertations

This work is concerned with the magnetic analysis of brushless DC motors, and, with the development of a method of designing brushless DC motors which have symmetric windings and rotors without any iron saliency. A two-dimensional nonlinear finite element magnetic model is used to analyze the magnetic behavior of the motor. Methods of using the finite element solution(s) to predict motor characteristic performance parameters, such as the torque-angle curve, detent torque-angle curve, torque constant, back emf constant and inductance are discussed in detail. It is shown that three-dimensional effects can make significant contributions to the motor inductance, making inductance prediction …