Engineering Commons^™

Optical And Magneto-Optical Characterization Of Tbfeco Thin Films In Trilayer Structures, William A. Mcgahan, Ping He, Liang-Yao Chen, Sal Bonafede, John A. Woollam, F. Sequeda, T. Mcdaniel, H. Do

Department of Electrical and Computer Engineering: Faculty Publications

A series of TbFeCo films ranging in thickness from 100 to 800 Å have been deposited in trilayer structures on silicon wafer substrates, with S₃N₄ being employed as the dielectric material. These films have been characterized both optically and magneto-optically by variable angle of incidence spectroscopic ellipsometry, normal angle of incidence) reflectometry, and normal angle of incidence Kerr spectroscopy. From these measurements, the optical constants n and k have been determined for the TbFeCo films, as well as the magneto-optical constants Ql and Q2. Results are presented that demonstrate the lack of dependence of these …

Study Of Joint Flexibility In Steel Frame Structures, Randy R. Frank

Opportunities for Undergraduate Research Experience Program (OURE)

Joint flexibility plays an important role in the distribution of strains and displacements in the frame structures of buildings, towers, automobiles, etc.. The objective of this project is to study the effect of flexibility (or rigidity) of two simple mechanical joints in frame structures on the stress and displacement distributions, using both experimental and analytical methods. Three welded and three bolted samples were fabricated using A-36 low carbon steel in a two column and horizontal crossmember (table) arrangement. This arrangement allows for both shear forces and axial forces in the joint. From a three element rectangular rosette strain gage attached …

Measurement Of Voltage And Current In Electric Power Systems, Michael Davis

Opportunities for Undergraduate Research Experience Program (OURE)

A. B. Chance Company of Centralia, Missouri requested a study of the latest state-of-the- art technology to measure voltage and current on a normal distribution power line. (4kV - 35kV)

The particular device that A. B. Chance needs must be relatively inexpensive, $200.00 per measurement, reliable, and capable of being manufactured by them.

Four types of power line measurement techniques were investigated; electrooptics/magnetooptics, present day measurement devices, the Raychem Line Monitor, and remote voltage and current sensing (RVCS).

The remote voltage and current sensing idea is the basis of the following report.

Identity Authentication Based On Keystroke Latencies Using Neural Networks, Angela Lammers, Sharon Langenfeld

Opportunities for Undergraduate Research Experience Program (OURE)

Most computer security systems verify the identity of a user through objects in the user's possession such as keys or magnetic cards, or through knowledge the user has, such as a password or PIN number. There are, however, two other methods of user verification, which have as yet received little or no attention. There has been some work done on the third method, recognition of physiological patterns (such as finger prints, retinal patterns, or voice patterns), but this work has been limited and requires expensive hardware to implement. The final method of user verification is through actions such as signature …

Bundled Cable Parameters And Their Impact On Emi Measurement Repeatability, Deanna L. Weil

Opportunities for Undergraduate Research Experience Program (OURE)

This research project was 99% experimental, therefore, not many theoretical ideas will be presented. The main idea behind the project was centered around cable bundling. The effect of cable bundling using analytical measurements and data from a network analyzer was investigated.

A Computer Simulation Of The Umr Reactor, H. Allen Wilkins

Opportunities for Undergraduate Research Experience Program (OURE)

The Opportunities for Undergraduate Research project entitled, "A Computer Simulation of the UMR Reactor" had two goals. To produce a reactor simulation to be used in creating an artificial intelligence based reactor simulation for the UMR Nuclear Reactor and to produce a means of teaching students the fundamentals of reactor operations.

The primary purpose was to create a program which would simulate all the situations one would encounter in actual reactor operation. With the simulator the artificial intelligence system could be thoroughly tested before use with actual reactor data.

This same simulator would be used as a teaching aid for …

The Detection And Quantification Of Atrophic Rhinitis Using Ditigal Image Processing Techniques, Timothy Mussman

Opportunities for Undergraduate Research Experience Program (OURE)

This project focuses its attention on the detection and quantification of Atrophic Rhinitis (A.R.), a disease prevalent in pigs. A.R. causes some of the bony structure in a pig's snout to atrophy, which exposes the animal to other diseases that may effect its growth. It is studied by examining a cross section of the pig's snout. By comparing areas and perimeters of the nasal cavity to bony structures, or turbinates in the snout, one can determine the severity of the atrophy. Currently, the veterinarians diagnosis is based on a subjective analysis of the snout. The problem with this method is …

Border Detection Of Skin Tumor Images, Mike Tiehes

Opportunities for Undergraduate Research Experience Program (OURE)

Border detection of skin tumor images is part of a research project whose purpose is to identify key features in skin tumor images using machine vision techniques. The key features present in a skin tumor guide the dermatologist in making the proper diagnosis. A few examples of key features are crust, scale and ulcer.

Noise Generators For The Simulation Of Digital Communication Systems, Martina F. Schollmeyer, William H. Tranter

Electrical and Computer Engineering Faculty Research & Creative Works

The generation of random numbers, having uniform and Gaussian distributions, with application to the time-domain simulation of communication systems is considered. The specific goal is to identify appropriate noise generation algorithms for use in system simulations for the determination of the symbol error probability of a digital communication system. Several methods of generating both uniform and Gaussian random numbers are examined. The algorithms considered were taken from those discussed in recent literature that appeared most appropriate for our problem. The algorithms were programmed in FORTRAN for use on a PC with math-coprocessor. Tests to evaluate the statistical properties of the …

An Architecture Level Simulation Methodology, Paul D. Stigall, Ram Huggahalli

Electrical and Computer Engineering Faculty Research & Creative Works

Using the Architecture Design and Assessment System (ADAS), the Processor Level Architecture of an Example Computer System is First Represented as a Directed Graph. Then, a Method of Simulating Instruction Execution as a Sequence of Data Transfers between the Nodes of the Graph is Presented. the Simulation Methodology Provides Flexibility in Observing the Architecture Dynamically at the Processor Level. an Example Application for Functional Verification is Discussed. Development of Techniques to Convert Programs into Node Sequences And, to Assign Appropriate Delays to the Nodes is Necessary to Further Enhance the Applicability of the Methodology. Functional Verification and Performance Estimation through …

An Erasable Optical Memory Based On Stimulated Electronic Transition Concept, James D. Satira

Electrical & Computer Engineering Theses & Dissertations

Erasable optical memory systems with a high storage density and a large data transfer rate are required for many real time data acquisition systems such as those placed aboard NASA's space born platforms. A new concept for erasable optical memory involving stimulated electronic transitions (SET) will meet these requirements. The SET concept useful in erasable optical storage systems was demonstrated in MgS and SrS doped with Eu and Sm. The optical properties of these materials were studied. The reading and writing wavelengths for these samples were determined to be 950 and 514 nm respectively. The peaks of the emission spectra …

A Modified Parallel Fault Simulator For Combinational Circuits, Shih-Ming Li

Masters Theses

The most commonly used model for fault analysis is called the "Stuck-At" model. With this model, a faulty gate input and/or output is modeled as Stuck-at-0 (s--a-0) or Stuck-at-1 (s-a-1). After a certain number of test vectors are applied to a network, the percentage fault coverage is computed. This computed value relates to the percentage of stuck-at faults detectable at the output. Various studies have been made to enhance the performance of fault simulators. In this paper, a modified parallel simulator MODPAR for combinational circuits is presented. A comparison of simulation results from MODPAR is made with that of SCIRTSS …

Channel Routing And Compaction: An Integrated Approach, Roshan A. Gidwani

Masters Theses

An attempt is made at integrating channel routing gnd compaction. A new gridless three-layer channel router based on an integrated approach to channel routing and compaction is presented. Routing is based on combined constraint graphs. Nets are selected from the input net list based on the criteria of ancestor and descendant weights in the combined constraint graphs. Compaction is done immediately after some nets are routed by using a via-segment graph. The router and compacter work hand-in-hand, i.e., the changes made by the compacter are available to the router, which enables the router to route more efficiently. Experimental results show …

Magneto-Optical Kerr Effect And Perpendicular Magnetic Anisotropy Of Evaporated And Sputtered Co/Pt Multilayer Structures, Ping He, William A. Mcgahan, John A. Woollam, F. Sequeda, T. Mcdaniel, H. Do

Department of Electrical and Computer Engineering: Faculty Publications

Thin and ultrathin Co/Pt multilayered structures have been prepared on glass substrates by electron-beam evaporation at room temperature and by sputtering at various substrate temperatures and sputtering pressures. Perpendicular magnetic anisotropy was found in samples with Co/Pt bilayer thicknesses near 3 Å/l0 Å and total thicknesses of the layer stack of no greater than 300 Å. X-ray diffraction was performed on the samples to determine layer spacing and integrity, and possible crystallinity of films. Crystalline structures in the interface between the Co and Pt layers were found and identified. The effects of sputtering parameters, such as pressure and substrate temperature, …

Phase Changes In Plasma‐Sprayed Zinc‐Nickel Ferrite, T. A. Dooling, Desmond C. Cook

Physics Faculty Publications

The magnetic and crystalline properties of a plasma‐sprayed coating of the microwave absorbing zinc‐nickel ferrite, (Zn_0.41Ni_0.59 )Fe₂O₄ have been studied at 300 K using the Mössbauer effect and x‐ray diffraction (XRD). Both techniques indicate that the plasma‐sprayed material separated into two phases. The first is a nickel‐rich phase with magnetic fields of 47.5 and 44.5 T at the tetrahedral and octahedral sites, respectively. The second is a zinc‐rich phase, zinc meta‐ferrite, having a small magnetic field of 4.2 T. The quadrupole splitting of this second phase is ΔE=0.34 mm s⁻¹, …

Q Improvement Of A 5.2 Ghz Te011 Cavity By Incorporating Y1Ba2Cu3O7-X, R. Joseph Leclear

Electrical & Computer Engineering Theses & Dissertations

Research is undertaken to apply high temperature superconducting material to improve the quality factor (Q) of a 5.2 GHz cylindrical resonant cavity. In particular, the approach is to electrophoretically deposit polycrystalline Y₁Ba₂Cu₃O_7-x (YBCO) on the conducting surface of the cavity cylinder. Spalling of the YBCO ceramic coating due to expansion and contraction of the cavity during sintering and testing is overcome by segmenting the cylinder. Results show that the Q of the cavity is increased over that of a copper cavity at temperatures below 60 K. At 20 K, improvement exceeds a factor …

Analytical Modeling And Simulation For Investigation Of A Digital Gas Filter Correlation Radiometer, Catherine P. Mcgowan

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates a digital gas filter correlation radiometer called the Tropospheric Radiometer for Atmospheric Chemistry and Environmental Research (TRACER), which will be used to remotely measure carbon monoxide at three levels in the troposphere. The nadir-viewing radiometer measures the differential absorption of radiation through the atmosphere at 4.67@m and 2.33pm wavelengths. This thesis develops an analytical model of the TRACER measurement process to evaluate the effect of varying certain system parameters on the measurement. The independent sampling criterion and the response of linear systems to random signals are explained. A parametric simulation model is also developed to evaluate the …

Monte Carlo Simulation Of Millimeter-Wave Gunn Effect Oscillators, Ramani Vaidyanathan

Electrical & Computer Engineering Theses & Dissertations

Monte Carlo simulations have been carried out to investigate the performance of microwave Gunn oscillators. Three separate aspects of the simulation problem have been comprehensively addressed in this work. First, the presence of an external circuit has been self-consistently incorporated into the calculations. The inclusion of the external circuit facilitates a study of the circuit controlled regime, and correctly models effects arising from the time dependent boundary conditions. Secondly, microscopic details of the electronic relaxation mechanisms which ultimately control the frequency response limits, have been taken into account through an iterative Monte Carlo-Poisson scheme. This procedure overcomes a potential shortcoming …

Signal Processing Methodologies For An Acoustic Fetal Heart Rate Monitor, Robert A. Pretlow Iii

Electrical & Computer Engineering Theses & Dissertations

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively "trained" in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the …

The Breakdown Mechanism Of Hollow Cathode Discharge, Mai Tuyet Ngo

Electrical & Computer Engineering Theses & Dissertations

In a low pressure discharge, if the cathode incorporates a cylindrical or slit shaped hole, the discharge current can be several orders of magnitude higher than in one with plane parallel electrodes under the same pressure and voltage conditions. In this work hollow cathode discharges in Helium under the influence of variable parameters such as gas pressure, applied voltage, electrode gap spacing, external magnetic field, etc., are investigated by means of electrical and optical diagnostic techniques.

The results indicate that a hollow cathode discharge develops in two stages. The initial breakdown occurs along the longest straight path of the system, …

Development And Characterization Of Monoclonal Antisperm Antibodies: Potential For Contraception, Dilrowshan H. Haque

Theses and Dissertations in Biomedical Sciences

There is an expressed need to develop a greater variety of safe contraceptive methods which would find acceptance worldwide, particularly in developing countries. Immunization against spermatozoa might be such a method as judged by the accumulated evidence from studies on human females and in a number of female animal species.

Two extraction techniques were used for sperm membrane antigen isolation. The first technique involved NP-40 detergent for antigen extraction from human motile sperm and the second technique employed homogenized human testis for antigen extraction. Using these immunogens, sperm membrane-specific monoclonal antibodies (MAbs) were developed. When these antisperm MAbs were subjected …

Magnetic-Field Distributions In Zinc-Nickel Ferrite, T. A. Dooling, Desmond C. Cook

Physics Faculty Publications

The Mössbauer effect has been used to study the microscopic magnetic properties of the cubic microwave ferrite (Zn_0.41Ni_0.59)Fe₂O₄ at 300 K. The magnetically split spectrum is broad and unresolved due to the overlap of the hyperfine magnetic fields at the tetrahedral and octahedral sites. This is caused by a distribution of magnetic fields at each site. The distribution is especially large and asymmetric at the octahedral site and is due to the fact that the iron atoms at this site are influenced by the presence of both iron and zinc at the tetrahedral …

Afit/Afosr Symposium On Applications Of Wavelets To Signal Processing, Volume Ii, Tutorial Notes, Gregory T. Warhola, Mark E. Oxley, Steven K. Rogers, Matthew Kabrisky, Bruce W. Suter

AFIT Documents

The Air Force Institute of Technology (AFIT) hosted the Symposium on Applications of Wavelets to Signal processing during 20-22 March 1991 at the AFIT Science and Research Center, Wright-Patterson AFB, OH. This was the first major academic meeting of its kind held at AFIT. The symposium was sponsored by the Air Force Office of Scientific Research (AFOSR), Bolling AFB, DC. It focused on applications of wavelets to problems in image and speech processing, communications, and graphics and opened with a one-day short course, 'A Tutorial on Wavelets.' The symposium was attended by more than 220 researchers worldwide. They represented 15 …

Modifications To Mcnp, Version 3b: Incorporating A Variable Density Atmosphere. Addendum, David L. Monti, Kirk A. Mathews

AFIT Documents

MCNP version 3B was modified to incorporate a continuously variable density atmosphere. This was accomplished by representing the variation of air density as a function of altitude with a series of continuous piecewise exponential curves up to a maximum altitude of 1000 km. User-written subroutines and functions were written which incorporated these piecewise functions. These subroutines and functions were subsequently incorporated into a production version of MCNP. Several MCNP subroutines and files were modified in support of these modifications. This report discusses detailed information regarding the theoretical development of the variable density model, the user written subroutines and functions, the …

A Fully Coupled, Automated Formation Control System For Dissimilar Aircraft In Maneuvering Formation Flight, Paul R. Rohs

Theses and Dissertations

This study developed a fully automated formulation control system, capable of controlling a number of like or dissimilar aircraft in maneuvering formation flight. C-130 fixed wing aircraft and H-53 helicopters were modelled in various formulations and simulated through a mix of maneuvers. External formation guidance was assumed as a single data burst of nominal function guidance commands and separation distances for each wing aircraft in the formation. No communication was assumed between formation aircraft. Wing aircraft track lead aircraft maneuvering with an ideal on-board sensor, maneuvering to maintain relative position. It was determined that lead aircraft inputs must be attenuated …

A Navigation Reference System (Nrs) Using Global Positioning System (Gps) Aiding, Richard D. Stacey

Theses and Dissertations

To quantify the performance abilities of existing or proposed navigation systems, the U.S. Air Force has for the last several years compared the performance of the system under test to the performance of a baseline navigation system known as the Completely Integrated Reference Instrumentation System (CIRIS). CIRIS obtains a highly accurate navigation solution by combining the output from three major subsystems: inertial navigation system (INS) information, barometric altitude information, and range and range-rate data from ground transponders which have been precisely surveyed. Although the navigation solution produced by CIRIS is highly accurate, it will soon be inadequate as the standard …

Identifiability In Wind Estimation From Scatterometer Measurements, David G. Long, Jerry M. Mendel

Faculty Publications

The problem of identifiability of a wind vector that is estimated from wind scatterometer measurements of the radar backscatter of the ocean's surface is addressed. The traditional wind estimation approach produces multiple estimates of the wind direction. A second processing step, known as dealiasing or ambiguity removal, is used to select a single wind estimate from these multiple solutions. Dealiasing is typically based on various ad hoc considerations. The traditional wind estimation approach results in multiple solutions associated with local minima in an objective function formed from the noisy backscatter measurements. The authors discuss the question of the uniqueness of …

The Synthesis Of Patterns Using A Series-Fed Array Of Annular Sector Radiating Line (Anserlin) Elements: Low-Profile, Circularly Polarized Radiators, James L. Drewniak, P. E. Mayes

Electrical and Computer Engineering Faculty Research & Creative Works

A series-fed, circularly polarized array of annular sector radiating-line elements that operates over a ground plane and has a low profile is presented. Pattern shaping can be achieved through control of the fraction of the incident power that is radiated by each element. This can be accomplished over a wide range by a simple adjustment in the geometry of each element. A synthesis technique is given, and experimental results are presented. The array is demonstrated to have a high return loss (good impedance match) and a low axial ratio

Quantum Network Theory Of Transport With Application To The Generalized Aharonov-Bohm Effect In Metals And Semiconductors, Cheng-Hsiao Wu, Gunter Mahler

Electrical and Computer Engineering Faculty Research & Creative Works

Quantum transport for resistor networks is developed with a general form factor, where each node point of the network is associated with a potential. The phase factor of the wave function in between two adjacent nodes is related to the reflection coefficient along that path. The exact transmission probability for a generalized Aharonov-Bohm ring is derived for a clean and cold crystal ring of arbitrary two-lead connections. The even- and odd-numbered rings have distinctly different transmission behaviors. The periodicity of the odd-numbered ring with respect to the threaded magnetic flux is shown to be double to that of an even-numbered …

Set-Valued Filtering And Smoothing, Wynn C. Stirling, Darryl Morrell

Faculty Publications

A theory of discrete-time optimal filtering and smoothing based on convex sets of probability distributions is presented. Rather than propagating a single conditional distribution as does conventional Bayesian estimation, a convex set of conditional distributions is evolved. For linear Gaussian systems, the convex set can be generated by a set of Gaussian distributions with equal covariance with means in a convex region of state space. The conventional point-valued Kalman filter is generated to a set-valued Kalman filter consisting of equations of evolution of a convex set of conditional means and a conditional covariance. The resulting estimator is an exact solution …