Engineering Commons^™

Analysis Of Frequency Selective Surfaces With Ferrite Substrates, Youcheng Liu

Retrospective Theses and Dissertations

Frequency selective surfaces (FSS) have numerous applications in several microwave and optical systems. Most frequency selective surface structures have one or more dielectric substrates. In this work, instead of traditional dielectric substrates, ferrite substrates are used under different dc bias conditions. By using ferrite materials, one can change the spectral properties of these structures without physically altering them. An applied magnetic field (dc bias) on the ferrite substrate changes its properties and hence the electrical dimensions of the elements comprising the periodic structure. Thus by simply applying a dc bias, the transmission and reflection properties of the periodic structure can …

Computing Optimal Cocomo Effort Multiplier Values And Optimal Casebase Subsets Using Monte Carlo Methods, Robert Joseph Maidhof

Retrospective Theses and Dissertations

There have been many studies performed and techniques applied to solve the problem of estimating man-month effort for software projects. Despite all the effort expended to solving this problem the results achieved from the various techniques have not been embraced by the software community as very reliable or accurate. This thesis uses Monte Carlo methods to obtain optimal values for COCOMO effort multipliers which minimize the average of the absolute values of the relative errors (AARE) of man-month estimate for two industry supplied casebases. For example, when using three COCOMO cost drivers (complexity, language experience, application experience) and the COCOMO …

Approximate Trigonometric Expansions With Applications To Signal Decomposition And Coding, Qurban A. Memon

Retrospective Theses and Dissertations

Signal representation and data coding for multi-dimensional signals have recently received considerable attention due to their importance to several modern technologies. Many useful contributions have been reported that employ wavelets and transform methods. For signal representation, it is always desired that a signal be represented using minimum number of parameters. The transform efficiency and ease of its implementation are to a large extent mutually incompatible. If a stationary process is not periodic, then the coefficients of its Fourier expansion are not uncorrelated. With the exception of periodic signals the expansion of such a process as a superposition of exponentials, particularly …

Cavity Model Analysis Of Microstrip Ring Antennas Using Green's Functions, Javier Gomez Tagle Rangel

Retrospective Theses and Dissertations

Microstrip ring antennas have been experimentally tested by several researchers due to their specific radiation characteristics that make them very suitable for many applications, from medical uses to mobile communications. Ring antennas have been found to have a larger bandwidth compared to other conventional types of microstrip patch antennas. Further more, their size is smaller when compared to circular and rectangular resonant structures. The TM1m modes (m = 2,4,6 .. , where m represents radial variations) radiate conical beams in the broadside direction, while TM nl modes (n = 2,4,6 .. , where n represents azimuthal variations) have a radiation …

Nonlinear Robust Control Of A Series Dc Motor Utilizing The Recursive Design Approach, Michael J. Burridge

Retrospective Theses and Dissertations

In this thesis, the investigation of asymptotic stability of the series DC motor with unknown load-torque and unknown armature inductance is considered. The control technique of recursive, or backstepping, design is employed. Three cases are considered. In the first case, the system is assumed to be perfectly known. In the second case, the load torque is assumed to be unknown and a proportional-integral controller is developed to compensate for this unknown quantity. In the final case, it is assumed that two system parameters, load torque and armature inductance, are not known exactly, but vary from expected nominal values within a …

Calculating Cross Slot Flux Losses In High Voltage Stator Coils, John D. Amos

Retrospective Theses and Dissertations

At present there are several methods for calculating temperature for inner-cooled stator coils for large electric generators. Determining the highest temperature in a stator coil is very important and is a major limiting factor for the maximum capability of steam turbine synchronous generators.

The load current in the stator winding causes losses in the conductor resistance. That same current excites leakage fluxes that link contours inside the conductors causing non-uniform current distribution and additional losses. these additional losses are caused by eddy currents induced inside the stator coils. These eddy losses are grouped as radial flux losses, cross slot flux …

Gaussian Beam Resonator Formalism Using The Yy Method, Kenneth A. Menard

Retrospective Theses and Dissertations

A simple and powerful new paraxial ray formalism is shown to provide an alternate method for designing Gaussian Beam Resonators. The theory utilizes the Delano yybar diagram approach and is an extension of the recent work by Shack and Kessler for laser systems. The method is shown to be complementary to the conventional ABCD method and is founded upon J.A. Arnaud's pioneering ideas for complex rays. The thesis develops an analytic formulation of a ray based complex wavefront curvature and yields a clearly generalized description of spherical wave propagation, for which Gaussian beams are considered a special case. The resultant …

Finite Impulse Response Utilizing The Principles Of Superposition, Scott Edward Carter

Retrospective Theses and Dissertations

Window functions have been greatly utilized in the synthesis of finite impulse response (FIR) filters implemented using surface acoustic wave (SAW) devices. The critical parameter in any FIR design in the impulse response length, which must be optimized for the given design specifications in order to reduce the size of each device. To this end, many design algorithms have been introduced such as Remez exchange, linear programming, and least mean squares. A new algorithm has been derived which is efficient and accurate for the design of arbitrary filter specifications requiring less computations than the current algorithms. The FIR design is …

Development Of A Desuperheater Rating Method For Energy Code Calculations, Tim Merrigan

Retrospective Theses and Dissertations

The purpose of this project was to develop a rating method for desuperheater water heaters – heat exchangers that remove superheat from the refrigerant in an air conditioner’s compressor discharge line. The project methodology was to first determine the overall heat transfer coefficient-area product (UA) of the heat exchanger for three basic types of desuperheaters. Both heat transfer analysis and the laboratory performance data indicated that the number of transfer units (NTU) for each heat exchanger was relatively independent of the operating conditions for a properly-charged air conditioner with a single-speed compressor and a desuperheater with a single-speed circulating pump. …

Computational Fluid Dynamics Study Of Swirling Sonic Jets, Murphy Leo O'Dea

Retrospective Theses and Dissertations

No abstract provided.

Implementation Of Ultrafast Optical Characterization Techniques, Nicholas J. Croglio

Retrospective Theses and Dissertations

The single beam Z-Scan technique, a two beam Pulse-Delay Modulation Technique (PDMT), and a combination of these methods are implemented to measure both nonlinear absorption and nonlinear refraction in semiconductors. The laser source used is a Kerr Lens Modelocked (KLM) Ti:sapphire laser producing tunable near IR 100 femtosecond pulses of ~5 nJ of energy per pulse at a 90 MHz repetition rate. Specifically we monitor two photon absorption and the bound electronic nonlinear refraction in ZnSe and this nonlinear refraction in ZnS. These techniques open the spectral range where these nonlinear optical parameters can be measured by allowing tunable high …

Color Image Enhancement Using Both Chromatic And Luminance Components, George Eric Hague Ii

Retrospective Theses and Dissertations

A vast amount of work has been published regarding grayscale processing of digital images. Although some of this work has been adapted for color images, many of the resulting algorithms neglect the correlation that exists between the individual RGB color components. Consequently, they introduce color artifacts. Attempts have been made to decouple the RGB components through color space transformations that isolate the luminance from the chromatic information. Color image enhancement is then considered a two step process, where the luminance and the chromatic components are processed independently. However, the RGB color space only has a finite number of available colors, …

Integration Of Artificial Neural Networks And Simulation Modeling In A Decision Support System, Kenney Lecroy

Retrospective Theses and Dissertations

A simulation based decision support system is developed for AT&T Microelectronics in Orlando. This system uses simulation modeling to capture the complex nature of semiconductor test operations. Simulation, however, is not a tool for optimization by itself. Numerous executions of the simulation model must generally be performed to narrow in on a set of proper decision parameters. As a means of alleviating this shortcoming, artificial neural networks are used in conjunction with simulation modeling to aid management in the decision making process. The integration of simulation and neural networks in a comprehensive decision support system, in effect, learns the reverse …

An Efficient Method For Representing And Computing Transitive Closure Over Temporal Relations, Vincent J. Kovarik

Retrospective Theses and Dissertations

The need for temporal reasoning is found throughout the engineering disciplines. James Allen introduced a representation for temporal reasoning based upon the concept of intervals. This approach provides a rich set of temporal relations for reasoning over events and changes in state. The full temporal algebra is NP-complete however. The algorithm developed by Allen executes in 0(n³) time but only ensures consistency between any three intervals.

This research presents an approach to representing interval relations as a bit-encoded form which captures the relationships between the end-points of the intervals. A bit-algebra is then defined which provides an …

Synthesis Of Numerical Integrators For The Real-Time Digital Simulation Of Continuous Systems, Michael James Panzitta

Retrospective Theses and Dissertations

Real-time digital simulation is a powerful means for engineers and scientists in government, industry, and academia to perform research and training as well as serving as a basis for many commercial applications. Due to the special constraints imposed by digitally simulating continuous systems in real time, however, many of these systems either require costly high-speed components or are unable to provide suitable performance characteristics using affordable computers.

This dissertation describes a new technique for the synthesis of numerical integrators specifically designed for the real-time digital simulation of continuous systems. This methodology is based upon the fact that the state derivatives …

Measuring And Compensating For Transport Delay In Real-Time Interactive Driving Simulation, Joseph D. Dumas Ii

Retrospective Theses and Dissertations

Real-time, man-in-the-loop simulators are important tools for operator training as well as human performance research. Simulator implementation using digital computers offers many important advantages but may also cause problems. One of the most significant and troublesome artifacts of digital computer simulation is the presence of transport delays in the operator/vehicle control loop. Transport delays have been shown to destabilize the system, resulting in poorer control of the simulated vehicle. They may also contribute to an increased likelihood of simulator sickness in human operators. Therefore, it is desirable to be able to quantify simulator transport delays and to compensate the system …

Phosphorus Accumulation In Bottom Sediments Of Retention/Detention Ponds, Kriss Young Kaye

Retrospective Theses and Dissertations

Laboratory and field studies were conducted to characterize phosphorus in bottom sediments for retention/detention ponds. The laboratory studies, including batch and column experiments, were conducted to assess possible removal processes. Sediment core samples were collected from detention ponds receiving urban runoff. These cores were analyzed for phosphorus at different layers including accumulated top sediments and the lower parent soil beneath it at a depth of 1, 3, 5, 10 and greater than 10 cm. The phosphorus accumulation rate was found to decline with calculated overflow rates from an average storm. Also attenuation of phosphorus with sediment depth followed an exponential …

Design And Construction Of Maintainable Knowledge Bases Through Effective Use Of Entity-Relationship Modeling Techniques, William Yancey Pike

Retrospective Theses and Dissertations

The use of an accepted logical database design tool, Entity-Relationship Diagrams (E-RD), is explored as a method by which conceptual and pseudo-conceptual knowledge bases may be designed. Extensions to Peter Chen's classic E-RD method which can model knowledge structure used by knowledge-based applications are explored. The use of E-RDs to design knowledge bases is proposed as a two-stage process. In the first stage, and E-RD, termed the Essential E-RD, is developed of the realm of the problem or enterprise being modeled. The Essential E-RD is completely independent of any knowledge representation model (KRM) and is intended for the understanding of …

Consumption And Loss Of Formaldehyde In Electroless Copper Plating, Peter John F. Sutch

Retrospective Theses and Dissertations

The objectives of this research were to quantify formaldehyde consumption due to plating and parasitic reactions and determine the magnitude and distribution of formaldehyde losses from the electroless copper plating process. Plating and rinse bath samples obtained from three electroless copper plating operations were analyzed for formaldehyde and copper in order to develop a mass balance analysis about the plating bath for periods of active production and no production. Fugitive air and stack releases of formaldehyde were estimated using emission factors developed from air sampling at the three facilities. It was determined that approximately 90% of the formaldehyde added to …

Non-Destructive Evaluation Of Space Shuttle Thermal Protection System Tile Bond Integrity, George David Mulligan

Retrospective Theses and Dissertations

Experimental modal analysis (EMA) is used as a non-destructive technique for the evaluation of Space Shuttle thermal protection system (TPS) tile bond integrity. Finite element (FE) models for tile systems were developed and were used to generate their vibration characteristics (i.e. natural frequencies and mode shapes). Various TPS tile assembly configurations as well as different bond conditions were analyzed. Results of finite element analyses demonstrated a drop in natural frequencies and a change in mode shapes which correlate with both size and location of disband. Results of experimental testing of tile panels correlated with FE results and demonstrated the feasibility …

Emissions Of Hexavalent Chromium From Hard Chromium Plating Operations, Mitchell Scott Hall

Retrospective Theses and Dissertations

This research addresses emissions of hexavalent chromium mist from hard chromium electroplating operations. Most of these emissions are typically captured by a ventilation stack and directed to a pollution control device; those which escape capture are called fugitive emissions. Releases of toxic materials such as hexavalent chromium must be reported annually to the Environmental Protection Agency (EPA) under provisions of the Superfund Amendments and Reauthorization Act (SARA) Title III of 1986 via the Toxic Release Inventory (TRI), Form R. The objectives were: (1) to provide estimates of fugitive hexavalent chromium emissions for the completion of Form R; and (2) to …

Express Transit Service For The University Of Central Florida, Arturo J. Perez

Retrospective Theses and Dissertations

As one of the fastest growing universities in the State of Florida, the University of Central Florida (UCF) is faced with the hardships placed on higher learning institutions across the nation. The increase of students paralleled by the increase of motor vehicles on the university campus, and the shortage of funding needed to construct the necessary parking facilities to support this growth, has left the University with a big dilemma, whether to try to overcome the parking space deficit by building the needed spaces to accommodate the demand, or provide a mass transit system that would reduce the number of …

Electromagnetic Focusing Properties Of Chirped Metallic Gratings, Jeffrey C. Schmidt

Retrospective Theses and Dissertations

The focusing properties of chirped diffraction gratings have long been studied and often used in applications at optical frequencies. Chirped metallic gratings of this type have also been studied theoretically at microwave frequencies, but no attempt has been made to experimentally examine or utilize the focusing properties of these structures at microwave frequencies. This thesis presents an experimental analysis of the focusing properties of chirped metallic gratings. These gratings are designed to focus electromagnetic energy at a predetermined position by varying strip width and spacing as a function of position. The diffraction gratings are characterized, and experimentally measured results are …

Microchannel Fluid Flow In A Silicon Chip, Ronald R. Ulseth

Retrospective Theses and Dissertations

The objective of this study was to analyze theoretically and experimentally the fluid characteristics of forced flow in microchannels. An apparatus was designed and constructed to allow microflow through a 450 μm wide by 17. 5 μm deep microchannel in a silicon chip. The flow through the chip was laminar with Reynolds numbers not exceeding 100. Tuckerman and Pease (1981) theorized that microscopic heat exchangers etched in the back of silicon chips could provide for efficient heat removal from the chips at rates much higher than the conventional methods could attain. The best technologies available provided for heat removal rates …

Surface Mapping And Automatic Tool Path Generation, Labiche Ferreira

Retrospective Theses and Dissertations

With the use of machine vision systems in the manufacturing cycle of a product, the lead time for producing the final product has been substantially reduced. Efforts in the past have aimed at automating the tasks right from the drawing board stage to final production of the product. Such technologies include CAD, CAM, and CAPP. However the task of tool path (NC code) generation has not yet been fully automated. In the current techniques, the user plays a crucial role in the NC code generation process. There is an increasing trend for using machine vision systems in the fabrication of …

Photorefractive Materials For Optical Signal Processing, William B. Lawler

Retrospective Theses and Dissertations

The optical response of the photorefractive crystals KNbO₃:Ta, KNbO₃:Fe, LiNbO₃:Fe, and nominally pure BaTiO₃ is investigated. In the experiment, a holographic grating is built in the crystal under investigation via a two-wave mixing scheme that utilizes the signal-processing capacities of two acousto-optic Bragg cells. The dynamic interaction of the Bragg cells with the photorefractive grating causes a heterodyned RF signal to appear on the output laser beam, enabling the real-time, direct measurement of the amplitude and phase of the space-charge fields in the crystal. Experimental results are presented for the amplitude and phase …

Application Of Case-Based Reasoning Techniques To The Automation Of Single-Family Residential Property Appraisals, Raymond Laureano-Ortiz

Retrospective Theses and Dissertations

Case-based reasoning has emerged as an alternative to rule-based reasoning techniques for the design of expert systems. This paper concentrates on the issues involved in the application of the case-based reasoning techniques to a specific domain, property appraisal. Case-based reasoning has been recently favored because it seems to resemble more closely to the psychological process human follows when trying to apply their knowledge to the solution of problems: People adapt solutions of similar problems they handled in past experiences to address present situations.

Property appraisal or valuation is a domain characterized by having a single parameter in its solution, that …

Closure Of Unlined Landfills, Brenda J. Westhorp

Retrospective Theses and Dissertations

No abstract provided.

The Extraction Of The Equivalent Circuit Parameters Of Surface Acoustic Wave Resonators, Brent H. Horine

Retrospective Theses and Dissertations

The application of the Electronic Industries Association suggested standard, EIA-512 [1], has been successfully applied to quartz crystal resonators for extraction of the equivalent circuit model parameters. This technique has been shown to be very successful in the operation range to several hundred megahertz. This same technique is proposed to be applied to many differing types of resonators through the full spectrum of frequencies. This thesis will discuss measurement and testing of Surface Acoustic Wave (Saw) resonators at the higher frequencies. The packaging configuration in conjunction with SAW devices can lead to significant parasitic effects. In order to successfully extract …

Counterpropagation Neural Network Detection Of Visual Primitives, Cynthia Lynn Johnson

Retrospective Theses and Dissertations

Psychological testing has shown that there is an early preattentive stage in the human visual system. At this level, simple features and properties of objects known as visual primitives are detected spatially in parallel by groupings of cells in the visual cortex known as feature maps. In order to study this preattentive stage in a machine vision system, the biologically inspired, highly parallel architecture of the artificial neural network shows great promise. This paper describes how the unique architecture of the counterpropagation neural network was used to simulate the feature maps which detect visual primitives in the human visual system. …