Engineering Commons^™

Three Dimensional Localization Of Lesions From Digitized Mammograms, Amy L. Magnus

Theses and Dissertations

This thesis describes new algorithms to localize regions-of-interests (ROIs) three dimensionally from a pair of digitized mammograms. This work is intended to add a layer of sophistication to computer aided diagnosis by putting to use the fixed and measurable parameters of mammographic imaging. The fixed parameters are the source to film orientation and the podium-image distance. Measurable parameters are the rotation angle of the x-ray tube from the horizontal and the compression depth (the distance from compression paddle to contact podium distance) at the time of imaging. As an additional benefit, three dimensional localization algorithms alleviate the confusion radiologists may …

Calibration And Measurement Of Dielectric Properties Of Finite Thickness Composite Sheets With Open-Ended Coaxial Sensors, Stoyan I. Ganchev, Nasser N. Qaddoumi, Sasan Bakhtiari, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

The application of open-ended coaxial sensors for dielectric measurement of finite thickness composite sheets is studied. Expressions for calculation of the complex aperture admittance for two geometries are presented. These expressions are used to calculate the dielectric constant of infinite half-space as well as finite thickness slabs. A more efficient method of such calculations, using a personal computer, for low to medium loss dielectrics is demonstrated. The question of when a dielectric layer may be considered as infinitely thick is also addressed, and examples are presented. A different calibration technique (compared to the conventional ones) is described and successfully implemented. …

A Massively Parallel Computation Strategy For Fdtd: Time And Space Parallelism Applied To Electromagnetics Problems, Michael A. Jensen, Amir Fijany, Yahya Rahmat-Samii, Jacob Barhen

Faculty Publications

We present a novel strategy for incorporating massive parallelism into the solution of Maxwell's equations using finite-difference time-domain methods. In a departure from previous techniques wherein spatial parallelism is used, our approach exploits massive temporal parallelism by computing all of the time steps in parallel. Furthermore, in contrast to other methods which appear to concentrate on explicit schemes such as Yee's (1966) algorithm, our strategy uses the implicit Crank-Nicolson technique which provides superior numerical properties. We show that the use of temporal parallelism results in algorithms which offer a massive degree of coarse grain parallelism with minimum communication and synchronization …

Binary Gas Mixture Analysis With An Interdigitated Gate Electrode Field Effect Transistor (Igefet) Microsensor, John M. Wiseman

Theses and Dissertations

Single component and binary gas mixtures of nitrogen dioxide (NO2) and ammonia (NH3) were analyzed with a microsensor composed of an array of interdigitated Gate Electrode Field Effect Transistor (IGEFET) sensor elements coated with copper-, nickel-, and cobalt-phthalocyanine thin films. Improvements in the IGEFET microsensor design and operation facilitated simultaneous measurement of ihe direct current (DC) and alternating current (AC) electrical response of the metal-substituted phthalocyanine (MPc) films to challenge gas exposure. A finite-difference model of the interdigitated gate electrode (IGE) structure confirmed the fundamental operation of the IGEFET microsensor. Principal component analysis (PCA) and multilinear regression were applied to …

Application Of Mixed-Norm Optimal Control To A Multi-Objective Active Suspension Problem, John B. Allison

Theses and Dissertations

Mixed norm optimal control synthesis is used to solve a multiobjective suspension problem. The objective is to develop a controller for an active suspension system onboard a tractor semitrailer vehicle. The problem is first approached by using H₂ and H∞ optimization. It is shown that by combining both techniques into one mixed norm optimization method, it is possible to exploit the strengths of each norm to provide superior performance. Two H₂/H∞ designs were completed. One design concentrated on optimal performance at one design condition. The second design concentrated on providing the best performance possible at a medium …

Adaptive And Fixed Wavelet Features For Narrowband Signal Classification, Anthony J. Pohl

Theses and Dissertations

The application of the multiresolution analysis developed by Mallat to signal classification by Pati and Krishnaprasad and Szu, et al, is further explored in this thesis. Several different wavelet based feature extraction and classification systems are developed and implemented. Methods which rely on the traditional dyadic wavelet decomposition and on the adaptive wavelet representation are presented. Each of the classification systems is implemented for a labeled data set of narrowband signals. Finally, classification results on the full data set and on low frequency Fourier coefficients are provided as baseline comparisons for our work.

The Role Of Frame Selection And Bispectrum Phase Reconstruction For Speckle Imaging Through Atmospheric Turbulence, Elizabeth A. Harpold

Theses and Dissertations

Frame selection using quality sharpness metrics have been shown in previous AFIT theses, to be effective in improving the final product of images obtained using adaptive optics. This thesis extends this idea to noncompensated speckle image data. Speckle image reconstruction is simulated with and without frame selection. Speckle images require the processing of hundreds of data frames. Frame selection is a method of reducing the amount of data required to reconstruct the image. A collection of short exposure image data frames of a single object are sorted based on sharpness metrics. Only the highest quality frames are retained and processed …

Analysis And Interpretation Of Ion Data Associated With Neutral Gas Releases In The Earth's Ionosphere, Timothy M. Shadid

Theses and Dissertations

Barium and strontium release experiments were conducted throughout 1991 from the Combined Release and Radiation Effects Satellite (CRRES) to study both natural and man-made disturbances in the earth's ionosphere. A mass spectrometer on the spacecraft counted the Ba and Sr ions as the cloud expanded. In this study, data from the G-1 (in sunlight) and G-11b (in darkness) releases were modeled to understand the source of the ion signals. The model reproduced the Ba⁺ sun data well assuming photoionization (τ = 28 s) was the primary ionization mechanism. However, it was not able to account for the remaining ion …

Design, Fabrication, Processing, And Testing Of Micro-Electro-Mechanical Chemical Sensors, Brian S. Freeman

Theses and Dissertations

Chemical microsensors are a new field integrating chemical thin film technology with solid-state fabrication techniques to make devices capable of detecting chemicals in the environment. This thesis evaluated commercially available fabrication processes and numerous sensor designs for working chemical sensors. The commercial processes used were MUMPS for surface micromachined devices and MOSIS for bulk micromachined devices. Overall, eight fabrication runs and 29 different designs were made. Of these designs, two were shown to work effectively. Other designs failed due to fabrication problems and design errors that caused release problems. One design that worked was a surface micromachined chemoresistor with interdigitated …

Evaluation Of The Sensitivity Of Radar Cross Section Predictions To Uncertainties In Material Characteristics, Greg A. Barnhart

Theses and Dissertations

The purpose of this study was to evaluate the effects of material characteristics uncertainties on Radar Cross Section (RCS) predictions. Many methods have been developed to predict the RCS of metal objects, but for material coated objects, these methods depend on the accuracy of measured material characteristics. Material characteristics of three dielectrics were measured by two separate X-band waveguide set-ups. RCS measurements were then made to evaluate the accuracy of RCS predictions using these measured material characteristics. A six inch square slab of each material was measured with and without a metal plate backing. A six inch square flat metal …

Effects Of Jamming And Excision Filtering Upon Error Rates And Detectability Of A Spread Spectrum Communication System, Christopher B. Madden

Theses and Dissertations

This thesis examines the effects of a digital excision filter (DEF) upon the error rates and detectability of a Direct Sequence Binary Phase Shift Keyed communication signal in the presence of both continuous wave (CW) and pulsed jammers. Simulations were performed using the Comdisco Signal Processing Worksystem. Detector models used were the wideband radiometer and two forms of the chip-rate detector. Twelve jamming scenarios were used to test the performance of the DEF in the presence of the CW and pulsed jammers. In addition, the effects of the CW jammer frequency, the pulsed jammer duty cycle, and the pulsed jammer …

Narrowband Interference Suppression In Spread Spectrum Communication Systems, James A. Lascody

Theses and Dissertations

Of significant interest to the United States military is the ability of an enemy to deny or disrupt the operation of the Global Positioning System. To combat this threat the GPS JPO initiated the Tactical GPS AntiJam Technology project, which yielded a prototype Digital Excision Filter (DEF) to remove narrowband jammers. This research describes the work performed to get the DEF hardware operational and extends the previous research performed in this area. Comdisco's Signal Processing Worksystem was used to examine the effect of the DEF on the probability of bit error. This research uses peak to average correlation value, probability …

Design Of Flight Control Laws For Aircraft With Flexible Wings Using Quantitative Feedback Theory, Christina L. Osmon

Theses and Dissertations

Aircraft composed of lightweight composite materials are extremely enticing since their structural weight is greatly reduced. However, the control of these aircraft is complicated by the resultant flexibility of the wings. Two avenues of approach are possible; stiffen the wings thus losing some of the weight reduction benefits, or design the lateral/directional flight control system cognizant of the wing's flexibility. In this thesis the second approach is taken. The design of three lateral/directional flight control systems for the sub-sonic flight envelope of the F-18 is presented. The Quantitative Feedback Theory (QFT) robust control design technique is used. These designs incorporate …

Three Dimensional Inverse Synthetic Aperture Radar Imaging, Jack D. Pullis

Theses and Dissertations

This research investigates the generation, display, and interpretation of three-dimensional (3-D) Synthetic Aperture Radar images. Three-dimensional assumes that the data collected consists of one temporal dimension and two orthogonal angular dimensions. From this data, a three dimensional reflectivity map, or 3-D image, of a target can be constructed. This thesis effort develops and applies a three-dimensional imaging algorithm on actual radar data measured on a one-third scale model of a C-29 aircraft. Two-dimensional slices of the three-dimensional image as well as three-dimensional isosurfaces are compared to the physical properties of the target. The results demonstrate the ability to produce three-dimensional …

Multiple Model Adaptive Control Of The Vista F-16, Michael J. Stepaniak

Theses and Dissertations

Multiple model adaptive control (MMAC) is investigated using the high-fidelity, nonlinear, six-degree-of-freedom Simulation Rapid-Prototyping Facility VISTA F-16. Detection of single actuator and sensor failures is considered, with an MMAC algorithm initially pursued which allows a controller specifically designed for each particular failure condition to replace the standard F-16 Block 40 flight control system (FCS) once the failure is detected. The synthesis of certain discrete-time LQG/PI controllers (those using control variables linearly dependent on state derivatives) is shown to be unattainable due to numerical difficulties. A novel control technique, termed control redistribution, is introduced which redistributes control commands (that would normally …

Computer Aided Detection Of Microcalcifications Utilizing Texture Analysis, Ronald C. Dauk

Theses and Dissertations

A comparative study of texture measures for the classification of breast tissue is presented. The texture features investigated include Angular Second Moments, Power Spectrum Analysis and a novel feature, Laws Energy Ratios. The texture study was accomplished as part of the development of a Model Based Vision (MBV) system for the automatic detection of microcalcifications. An overview of the Microcalcification Detection System is presented, which applies image differencing techniques, feature selection methods, and neural networks for locating microcalcification clusters in mammograms. The Power Spectrum Analysis feature set had the best overall performance with an 83% Probability of Detection and an …

Effects Of Neutron Radiation On Resonant Cavity Light-Emitting Diodes, Daniel S. Hinkel

Theses and Dissertations

Resonant Cavity Light Emitting Diodes (RCLEDs) were irradiated in Ohio State University's nuclear reactor to determine the effects of Neutron displacement damage. The RCLEDs were characterized both before and after irradiation by their current versus voltage curves (I-V curves) and external light power versus current curves (L-I curves). The I-V curves showed an increase in the "knee voltage" at a neutron fluence of 1.45x10¹⁷ neutrons/cm2. Logarithmic decreases in external light power and differential quantum efficiency were observed. Significant decreases in external light power were observed at neutron fluences greater than 5.1x10¹³ neutrons/cm². Equations were developed to …

Two-Wavelength Neodymium Based Lasers, Scott H. Mccracken

Theses and Dissertations

A dual wavelength Q switched laser cavity has been successfully designed and assembled to evaluate the new neodymium (Nd) based materials. Initial characterization has been achieved for Nd:YAG and Nd:YLF. The results indicate that for a fixed pulse repetition frequency, the delay time can be used to adjust the relative energy between the 1.06 and 1.32 micrometer pulses. Any deficiency in the performance of one transition can be made up by performance in the other simply by changing the relative amount of time the population inversion is allowed to build up for each pulse. The best performance was obtained using …

Space Object Identification Using Spatio-Temporal Pattern Recognition, Gary W. Brandstrom

Theses and Dissertations

This thesis is part of a research effort to automate the task of characterizing space objects or satellites based on a sequence of images. The goal is to detect space object anomalies. Two algorithms are considered - the feature space trajectory neural network (FST NN) and hidden Markov model (HMM) classifier. The FST NN was first presented by Leonard Neiberg and David P. Casasent in 1994 as a target identification tool. Kenneth H. Fielding and Dennis W. Ruck recently applied the hidden Markov model classifier to a 3D moving light display identification problem and a target recognition problem, using time …

Catalytic Oxidation Of Methanol On Pt/C-Spe And Ptru/C-Spe Electodes, Aihua Su, Changzhi Li, Gongquan Sun, Ying Zhang, Tianhong Lu

Journal of Electrochemistry

Anode catalysts of methanol oxidation for direct methanol fuel cell, Pt/C and PtRu/C, ere prepared by chemical reduction in this work. The results indicated that the PtRu/C showed higher electrocatalytic activity than that of Pt/C. It was explained by XRD and XPS analyses that the existence of Ru enhanced the catalytic activity for electrochemical oxidation of methanol.

A Photoelectrochemical Investigation Of A.C.Modulated Passive Films On 304 Stainless Steel In Weak-Alkaline And Neutral Solution, Tianbao Du, Chunan Cao, Jiakang Yu, Haichao Lin

Journal of Electrochemistry

A photoelectrochemical investigation has been carried out on AISI 304 stainless steeI AV modulated passive film in 0.1mol/L Na₂B₄O₇ and 0.5 mol/L Na₂SO₄ solution. Photo current curve depends on the potential, passive condition and testing solutions. The results of the measurements indicate that the photoresponse is determined by the defects in the electronic structure of the films whenthe defects lead to localized states in the bandgap region. It is concluded that the passive film on AISI 304 stainless steel is in a highly disordered amorphous state.

Study Of The Modified Electrolytic Manganese Dioxide, Guohui Yuan, Dewei Chu, Rihui Shen, Hongwei Pan, Cuifen Zhang

Journal of Electrochemistry

A modified electrolytic manganese dioside doped with Bi (Bi-EMD)wasprepared and examined by XRD and XPS. It is predominantly γ-mnO₂ and the Bi exists as Bi₂O₃ in the modified material. The content of Bi in Bi-EMDs increased with the increasement of Bi³⁺ concentration in electrolyte, and reached 14.3(wt)% from the bath of 0.008 mol·L^-1 Bi³⁺ used. Some Zn/Bi-EMD prototype batteries of AA size were assembled, and which cycle life tests showedthat the Bi-EMD has better reversibility.

Influence Of O-Phenylenediamine On The Catalysis At Hrp Enzyme Electrode In 1,4-Dioxane, Hong Chen, Hui-Huang Wu

Journal of Electrochemistry

Horseradish peroxidase (HRP) was immobilized by crosslinkage on the glassycarbon electrode to prepare the enzyme electrode, where the reduction of H₂O₂ was studied in 1,4-dioxane media. It was shown that HRP electrode can catalyze the reduction of H₂O₂ without anymedintor, however, as an activator, o-phenylenediamine can promote the bio-catalysis. In thepresence of the activator, the parallel reactions occurred on the enzyme electrode. The workingcondition of the HRP electrode was investigated as the sensors for H₂O₂ and o-phenylenediamine, also the influence of water content in organic phase was discussed on the performance …

Equivalent Relationship Of Function-Level Representation And Implementation Of Unified Indexing Of Fft Algorithms, Nee-Hua Cho

Dissertations and Theses

With the advance of the VLSI technology, the FFT algorithm has been pushed further in solving the multidimensional array signal processing in real time. Many DSP chip users have tried to find ways to improve addressing huge data in multidimension systems with minimum cost and maximum performance. However, there is no efficient method to address data for 1-D to M-D FFTs.

A methodology has been defined to conquer the addressing problem of M-D FFT. It is well known that the twiddle factor matrix of Discrete Fourier Transform (DFT) can be recursively factored into basic butterfly stage matrices. The matrix can …

Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard T. Masters, Martin B. Mark, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing pulse introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally …

Heterodyne Ladar System Efficiency Enhancement Using Single-Mode Optical Fiber Mixers, Donald K. Jacob, Martin B. Mark, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

A theoretical performance analysis of a heterodyne ladar system incorporating a single-mode fiber receiver has been performed. For our purposes, the performance parameters of interest are the coupling and mixing efficiency of the ladar receiver, as they relate to the overall system carrier-to-noise ratio. For a receiver incorporating a single-mode fiber mixer, the received and local-oscillator fields are matched both spatially and temporally at the detector, yielding 100% mixing efficiency. We have therefore focused our efforts on determining an expression for the efficiency with which a diffuse return from a purely speckle target can be coupled into the receiving leg …

Image Restoration Of Dispersion-Degraded Images From A Liquid-Crystal Beam Steerer, Ronald J. Broessel, Vince Dominic, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

Liquid-crystal arrays represents one of the first practical technologies capable of steering light by electronic control only. We use such a device to steer the field of view of a broadband imaging sensor. Unfortunately, dispersion degrades the image quality by smearing out details in the image and by introducing multiple diffraction orders (echoes) at the detector plane. We present a method to compensate for these unwanted effects and thus restore the broadband images obtained with the beam steerer. We use the beam-propagation method to find the wavelength-dependent impulse response, from which we determine the appropriate Wiener filter. When training data …

Aliasing Reduction In Staring Infrared Imagers Utilizing Subpixel Techniques, Joseph C. Gillette, Thomas M. Stadtmiller, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

We introduce and analyze techniques for the reduction of aliased signal energy in a staring infrared imaging system. A standard staring system uses a fixed two-dimensional detector array that corresponds to a fixed spatial sampling frequency determined by the detector pitch or spacing. Aliasing will occur when sampling a scene containing spatial frequencies exceeding half the sampling frequency. This aliasing can significantly degrade the image quality. The aliasing reduction schemes presented here, referred to as microscanning, exploit subpixel shifts between time frames of an image sequence. These multiple images are used to reconstruct a single frame with reduced aliasing. If …

Spectroscopic Ellipsometric Monitoring Of Electron Cyclotron Resonance Plasma Etching Of Gaas And Algaas, Paul G. Snyder, Natale J. Ianno, B. Wigert, S. Pittal, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

In situ real time spectroscopic ellipsometry measurements were made during electron cyclotron resonance plasma etching of radio frequency biased GaAs and AlGaAs samples. Gas mixtures used were CH₄/H₂/Ar, pure H₂ , and pure Ar. Ellipsometry provided information about damage to the surface region and AlGaAs epilayer thickness. For the methane mixture GaAs etch, damage appeared in the form of redshifted and broadened E₁ and E₁+ Δ₁ critical point features in a surface layer several tens of nm thick. The damage layer began forming within a few seconds after the start of …

An Algorithmic Approach To Loop Shaping With Applications To Self-Tuning Control Systems, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

An algorithmic approach to feedback control design is introduced. It simplifies the existing iterative design process, which is often tedious, by reducing the design problem to solving a set of linear algebraic equations. The algorithmic nature of such an approach makes it attrative to not only off-line designs but also self-tuning control systems, where the compensators are continuously tuned on-line as the dynamics of the physical process vary with time. This is demonstrated in the example where the proposed algorithm is implemented for an industrial tension regulation system with successful simulation results. Extensions of the algorithm to …