Physical Sciences and Mathematics Commons^™

Experimental Investigation Of Nonlinear Dynamics In Single Mode Semiconductor Laser Diodes With Phase Conjugate Feedback, Gordon T. Hengst

Theses and Dissertations

The semiconductor laser diode offers a unique system to investigate nonlinear dynamics when optical feedback is applied. Although there is extensive research of laser diodes with optical feedback from normal dielectric mirrors, very little has been done experimentally to analyze the effects of degenerate phase conjugate feedback from a BaTiO₃ crystal. This research experimentally investigated the dynamics of a single-mode laser diode with weak phase conjugate feedback using both the self-pumped and double phase conjugate geometries. The experimental results validated a mathematical model which numerically evaluates the Lang-Kobayahsi coupled differential equations. The model simulated the nonlinear behavior of a …

Autonomous Construction Of Multi Layer Perceptron Neural Networks, Thomas F. Rathbun

Theses and Dissertations

The construction of Multi Layer Perceptron (MLP) neural networks for classification is explored. A novel algorithm is developed, the MLP Iterative Construction Algorithm (MICA), that designs the network architecture as it trains the weights of the hidden layer nodes. The architecture can be optimized on training set classification accuracy, whereby it always achieves 100% classification accuracies, or it can be optimized for generalization. The test results for MICA compare favorably with those of backpropagation on some data sets and far surpasses backpropagation on others while requiring less FLOPS to train. Feature selection is enhanced by MICA because it affords the …

Kinetics And Spectroscopy Of Brno, Patrick E. Godfrey

Theses and Dissertations

The infrared spectra and photochemistry of nitrosyl bromide, BrNO, are important to characterizing the performance of a recently demonstrated Br(²P_1/2)-NO(v=2 → v=1) transfer laser pumped by photolysis of iodine molecules. This wavelength agile, mid-infrared laser may be a desirable source for remote sensing and infrared countermeasures missions. Nitrosyl bromide also plays a role in the destruction of stratospheric ozone. The kinetics of BrNO formation and destruction were examined using time-resolved photolysis techniques. The equilibrium constant for the dark reaction Br₂ + 2NO (reversible reaction) 2BrNO was determined as K_eq 168 ± 23 /atm and …

Optimization Considerations For Adaptive Optics Digital Imagery Systems, Robert T. Brigantic

Theses and Dissertations

This dissertation had three objectives. The first objective was to develop image quality metrics that characterize Adaptive Optics System (AOS) performance. The second objective was to delineate control settings that maximize AOS performance. The third objective was to identify and characterize trade-offs between fully and partially compensated adaptive. For the first objective, three candidate image quality metrics were considered: the Strehl ratio, a novel metric that modifies the Strehl ratio by integrating the modulus of the average system optical transfer function to a 'noise-effective-cutoff' frequency at which some specified image spectrum signal-to-noise-ratio level is attained, and the noise-effective-cutoff frequency. It …

A Descriptive Survey Of Freshwater Unionidae Bivalves In Five Creeks Located In West Central Georgia, Rufus Carson Stringfellow

Theses and Dissertations

A descriptive survey of the West Georgia, Chattahoochee River drainage unionid bivalve fauna inhabiting Mountain Oak, Mulberry, Standing Boy, and Upatoi Creeks has been completed. The survey is intended to determine whether Unionidae populations remain extant in this portion of the Chattahoochee River drainage, and to estimate the abundance and distribution of species encountered. Accessibility sampling was employed; sites selected to be surveyed were usually located at a road bridge or some landmark easily identifiable for geographical positioning. Collecting methods included the use of a small rake in sandy or silty substrate, visual detection of siphons or trails in the …

Physiologically-Based Vision Modeling Applications And Gradient Descent-Based Parameter Adaptation Of Pulse Coupled Neural Networks, Randy P. Broussard

Theses and Dissertations

In this research, pulse coupled neural networks (PCNNs) are analyzed and evaluated for use in primate vision modeling. An adaptive PCNN is developed that automatically sets near-optimal parameter values to achieve a desired output. For vision modeling, a physiologically motivated vision model is developed from current theoretical and experimental biological data. The biological vision processing principles used in this model, such as spatial frequency filtering, competitive feature selection, multiple processing paths, and state dependent modulation are analyzed and implemented to create a PCNN based feature extraction network. This network extracts luminance, orientation, pitch, wavelength, and motion, and can be cascaded …

Developmental Taxonomy And Distribution Of Paralarval Squid From The Florida Current, Carrie Leeonne Adams

Theses and Dissertations

Distribution patterns of paralarval squid across the continental shelf of Florida were examined based on five years of collections. Squid occurrence patterns were described in relation to coastal, intermediate, and Florida Current (Gulf Stream) water masses by comparing horizontal and vertical distribution patterns of squid species to physical-chemical distribution patterns Twenty-six squid taxa were collected in this study. Representative taxonomic descriptions and illustrations of all taxa were produced to serve as an identification aid for the paralarval squid from the Florida shelf. Patterns of species composition among stations were analyzed with cluster analysis based on four sampling approaches. Species distribution …

Evaluation And Application Of Space Telescope Aberration Sensing Using Phase Diversity, David J. Lee

Theses and Dissertations

Due to mechanical aspects of fabrication, launch, and operational environment, space telescope optics can suffer from unforeseen aberrations, detracting from their intended diffraction-limited performance goals. This dissertation gives the results of simulation and theoretical studies designed to explore how wavefront aberration information for such "nearly diffraction-limited" telescopes can be estimated via the Gonsalves (least-squares) phase diversity technique. In traditional phase diversity, aberrations are estimated from two images—one conventional, focused image and one image that has been defocused by a known amount. These studies are original and significant in that this effort represents the first time the effects of photon noise …

Net-Centric Design And Analysis Of Information Systems, Timothy R. Schmoyer

Theses and Dissertations

This thesis presents a unique methodology merging state of the art Internet and distributed database technology to support distributed simulations with programming language and platform independence. Standardized models of Command, Control, Communications, Computers, and Intelligence (C4I) systems using Integrated Definition (IDEF) models and executable simulation objects are placed in database repositories which can be accessed and implemented over a distributed simulation network using the Common Object Request Broker Architecture (CORBA). The CORBA distributed simulation network accesses heterogeneous distributed databases, performs distributed processes, and supports portability and reuse of simulation objects and interoperability across operating systems and programming languages.

An Examination Of The Hanson Contrail Forecast Algorithm Under Low Relative Humidity Conditions, Robert P. Asbury Iii

Theses and Dissertations

Accurate forecasts of contrail occurrence are essential to military aircrews. Although classical forecast methods have been reasonably successful predicting contrails, there is need for improvement at low ambient relative humidity. This thesis examines the performance of the Hanson method, which was developed to provide better contrail forecasts under drier atmospheric conditions. As a secondary objective, the forecast methods of Schumann and Hanson are compared to the algorithm currently in use by the Air Force Global Weather Central. Data used to validate the algorithms were collected at Wright-Patterson AFB, OH and Edwards AFB, CA. Theoretical contrail forecasts were made for each …

Validation Of The Air Force Global Weather Center Relocatable Window Model Total Cloud Forecast, Edward C. Harris

Theses and Dissertations

Air Force Global Weather Center's (AFGWC) Relocatable Window Model (RWM) total cloud forecasts were validated using data for selected days in May, June, and July, 1996. Forecasts were generated twice daily (00 UTC and 12 UTC) to determine the RWM's ability to accurately forecast total cloud cover during the late spring and early summer. The RWM forecasts were post-processed using the Slingo cloud forecast algorithm and compared against AFGWC's operational real time nephanalysis (RTNEPH) cloud analysis model. As a minimal-skill baseline comparison to the RWM's total cloud forecast, the RTNEPH initial analysis hour was persisted and evaluated against the same …

Adaption Of The Air Weather Service Fog Model To Forecast Radiation Fog Events In The Southeast United States, Andrew C. Goodnite

Theses and Dissertations

This research examined the performance of the Air Weather Service (AWS) Fog Model and the potential for using it in the Southeast United States for predicting fog. This task was accomplished in four separate steps. First, a correlation study was performed by comparing different weather elements in observations that met radiational cooling conditions to the observed visibility. This correlation study showed that the 22 UTC dewpoint depression was correlated (0.60) with early morning fog and no other weather elements that are commonly observed had significant correlation with early morning fog. Second, a verification study was conducted on the Saint Louis …

Quantification Of Weather Effects On Imaging Laser Radar, Clifton D. Stargardt

Theses and Dissertations

The Air Force is investigating the use of imaging laser radar systems as autonomous guidance systems on future precision guided munitions. The Air Force's Wright Laboratory is currently testing a 1.06 micron wavelength laser radar (ladar) at Eglin Air Force Base. Since laser radiation can be susceptible to propagation problems through weather, quantitative understanding of these effects is important to the development of this weapon system. Ladar image degradation, in the form of target dropouts and false returns, was evaluated in various weather conditions. Statistical analysis of the images presented expected degrees of degradation according to visibility and rain fall …

Analyzing And Improving Stochastic Network Security: A Multicriteria Prescriptive Risk Analysis Model, David L. Lyle

Theses and Dissertations

This research optimized two measures of network security by hardening components and improving their reliability. A common measure of effectiveness (MOE) for networks is statistical reliability, which ignores the effects of hostile actions. A new MOE which includes hostile actions was developed. Both measures require component reliability functions, derived using fault trees. Fuzzy Logic and Monte Carlo simulation were used to quantify uncertainty. Results from the model are compared to traditional Risk Assessment results.

A Validation Study Of The Ssm/I Temperature Algorithm And Comparison With The Cal/Val Land Surface Temperatures, Ronald L. Comoglio

Theses and Dissertations

The USAF operational cloud model, the Real-Time Nephanalysis (RTNEPH), requires infrared and visual scene scans as well as input from the Special Sensor Microwave Imager (SSM/I), featured on the Defense Meteorological Satellite Program (DMSP) polar orbiters. Additionally, SSM/I provides input to the Air Force Global Weather Center (AFGWC) surface temperature model (SFCTMP). The global surface temperatures are required for identifying which pixel of a scene is cloud and which is ground and as a first guess input to initialize NWP models. The SSM/I provides brightness temperatures sampled at four discrete: frequencies and dual polarizations to produce surface temperatures. Two algorithms …

Optimization Of The Velocity Azimuth Display (Vad) Algorithm's Adaptable Parameters In The Wsr-88d System, Donald R. Farris

Theses and Dissertations

Meteorologists have encountered problems with the Velocity Azimuth Display (VAD) algorithm in the Weather Surveillance Radar - 1988 Doppler (WSR-88D) System. Under certain meteorological conditions, forecasters have observed differences between the radar's wind profiles and wind profiles from rawinsonde upper-air soundings, or wind profilers. One of the main causes of this problem is inversions in the atmosphere which cause the radar beam to subrefract or superefract, causing the VAD winds to be inaccurately reported at a particular height. This thesis used the WSR-88D Algorithm Testing and Display System (WATADS) to compare VAD winds from recorded Level 2 NEXRAD data at …

A Comparison Of Circular Error Probable Estimators For Small Samples, Charles E. Williams

Theses and Dissertations

Several previous studies investigated the performance of competing circular error probable (CEP) estimators for small samples. This estimation is important in ICBM analysis because, due to expense, there are a limited number of ICBM test launches. In the most recent previous study (1993), Tongue considered five CEP estimators in a simulation test, attempting to determine the behavior of these estimators for populations of various bias, ellipticity, correlation, and sample size. In this paper, we build on Tongue's findings in three ways: (1) The number of estimators compared is expanded to eight. (2) Different factors and factor levels are used. (3) …

Automatic Digital Processing For Calibration Data Of Open Skies Treaty Sensors, Donna D. Keating

Theses and Dissertations

The Open Skies Treaty provides guidelines allowing participants to fly in air space over other participants' countries to monitor strategic military placement and development. The treaty restricts the ground size of the smallest detail recorded by these aerial imaging systems to any size larger than 30 cm. This restriction is enforced by placing a lower limit on the altitude at which a participating aircraft can fly and it is computed as the value of Hmin. Current techniques rely on human photographic interpreters to select the value of Hmin for every calibration pass and is very resource intensive. The Open Skies …

An Atmospheric Sensitivity And Validation Study Of The Variable Terrain Radio Parabolic Equation Model (Vtrpe), Matthew K. Doggett

Theses and Dissertations

The Variable Terrain Radio Parabolic Equation (VTRPE) computer model is a powerful and flexible program that provides calculations of the radar propagation conditions of the atmosphere. It is limited however, by the accuracy and resolution of the input data. This study quantifies the sensitivity of the VTRPE model to the accuracy and resolution of the atmospheric parameters that go into it. Also, two case studies are examined to test the utility of VTRPE in operational use. The sensitivity to measurements of pressure, temperature, and humidity was found to be dependent on the meteorological environment. In standard and subrefractive environments, average …

Development And Implementation Of An Isentropic Potential Vorticity Algorithm For Use At Air Force Global Weather Center, Jay B. Desjardins Jr.

Theses and Dissertations

This thesis presents and validates methods for calculating isentropic potential vorticity (IPV) and applies these methods in software programs planned for implementation at the Air Force Global Weather Center (AFGWC). The IPV programs will provide Air Force Weather forecasters additional tools to diagnose atmospheric kinematics and understand atmospheric dynamics. A FORTRAN program is recommended using mandatory-level isobaric data projected to be available on AFGWC computer systems, specifically, from the Navy Operational Global Atmosphere Prediction System and Medium Range Forecast models. Program development and analysis consists of three main steps: (1) data retrieval; (2) IPV calculations; and, (3) interpolation to an …

Moisture Sensitivity Of Contrail Forecast Algorithms, Allen C. Rabayda

Theses and Dissertations

This thesis looked at using new relative humidity (RH) climatologies to improve the Air Force Global Weather Center's (AFGWC) contrail forecasts. To study the effect of the new RH climatolgies, the currently used empirical relative humidity (RH) profile is replaced with a more accurate climatological one, the Stratospheric And Gaseous Experiment II (SAGE II). The study begins by examining accuracy and bias of forecast contrail bases generated by the empirical and SAGE II RH profiles on 42 days. Both sets of forecast bases are shown to be statistically similar with a series of hypothesis tests. Additional RH profiles, from 0% …

Object Matching Using The Dynamic Programming Algorithm, Rhoda Baggs Koss

Theses and Dissertations

A new algorithm for matching objects between images is developed and investigated. Affine transformations, i.e. those with translation, rotation, scaling and shearing between images are considered. Steps along the way include segmentation of the 2 images (referred to as the reference and inspected images), contour tracing of each segment/object in each image, the creation of objects via a new object representation scheme known as length codes (developed in [3]), and the application of the new dynamic warping algorithm. New original concepts include the use of the dynamic warping algorithm on sequences of length codes in order to determine the k …

Experiments In Aggregating Air Ordnance Effectiveness Data For The Tacwar Model, James E. Parker

Theses and Dissertations

An interactive MS Access&trademark; based application that aggregates the output of the SABSEL model for input into the TACWAR model is developed. The application was developed following efforts to create a functional approximation of the SABSEL data using neural networks, statistical networks, and traditional statistical techniques. These approximations were compared to a look-up table methodology on the basis of accuracy, (RMSE

Response Surface Methodology: An Analytical Method For Locating Migrated Contaminant Sources, Orlando J. Dona Jr.

Theses and Dissertations

The use and storage of hazardous chemicals at U.S. military facilities often adversely affect the groundwater when contaminants infiltrate the subsurface as a result of leaks and accidental spills. These contaminants, if not located and remediated in a relatively short time, may move and settle unpredictably, essentially creating a source some distance from the original leak or spill. An example of this phenomenon is found with migrating dense nonaqueous phase liquid (DNAPL) contaminants. Although various methods for estimating the present day locations of these migrated contaminants are in use, accurately pinpointing the source of contaminants remains a difficult problem in …

Spectroscopic And Kinetic Studies Of Bismuth Dimers, Robert Eugene Frankin

Theses and Dissertations

The spectroscopy of high rotational levels (J ≤ 211) in Bi₂ X(O_g⁺) and A(O_u⁺) was investigated for 2≤v"≤5 and 0≤v'≤4 by observing total fluorescence from laser excitation. Dunham coefficients were derived that fit all observed rotational lines to within 0.01 cm^-1. Franck-Condon factors were calculated and experimentally verified for transitions originating from the initially populated levels 0≤v'≤5. Vibrational energy transfer upon collision with rare gas collision partners was investigated for the low-lying vibrational levels of the A-state using spectrally resolved, continuous wave laser induced fluorescence. Vibrational transfer was adequately modeled by …

Chemistry And Environmental Implications Of Thio-Red And 2,4,6-Trimercaptotriazine Compounds, Kevin R. Henke

Theses and Dissertations

Many compounds, including Thio-Red® and 2,4,6-trimercaptotriazine, trisodium salt (TMT-55), have been marketed to precipitate mercury and other heavy metals from water, including contaminated ground waters. For the products to be effective, information is needed on the chemistry of the products, how they precipitate metals from aqueous solutions, and the chemistries and stabilities of the precipitates.

CS32-, HS-, and S2- are the dominant sulfur species in Thio-Red®. They precipitate heavy metals from water as sulfides (e.g., HgS, PbS, and ZnS). Thio-Red® also contains traces of poisonous carbon disulfide (CS2). Additional CS2 could form from reactions between dissolved heavy metals and CS32-. …

Investigation Of The Optical Properties Of Ordered Semiconductor Materials, Jack E. Mccrae Jr.

Theses and Dissertations

Optical studies have been conducted upon CdGeAs₂ and ZnGeP₂, two of the most promising semiconductors being developed for mid-infrared non-linear optics applications. These experiments included photoluminescence (PL) studies of both compounds as well as photoreflectance (PR) measurements upon CdGeAs₂. In addition, Hall effect measurements were carried out upon CdGeAs₂, to aid in interpretation of the optical data. PL was measured as a function of laser power, sample temperature, and crystal orientation for CdGeAs₂. One broad weak peak near 0.38 eV, and another somewhat narrower and often far brighter peak near 0.57 …

Knickpoint Analysis Of Streams In North Dakota, South Dakota, And Nebraska, Trent D. Hubbard

Theses and Dissertations

Analysis of stream profiles, seismic reflection studies, engineering studies, and historical earthquakes indicates uplift in south-central South Dakota and north-central Nebraska over the last 5-10 ma. The purpose of this study was to determine if this uplift could be detected by constructing topographic profiles along, and in close proximity to several streams in this region. The Cannonball River, ND, was used to compare the streams in South Dakota and Nebraska to a stream beyond the affected area.

Data for the profiles were collected from 7 .5 minute topographic maps as well as GPS surveys. Abrupt changes in slope (irregularities) were …

Four-Wave Mixing And Optical Phase Conjugation In Vertical Cavity Surface Emitting Devices, Gregory J. Vansuch

Theses and Dissertations

Four-wave mixing (FWM), a nonlinear optical process, was investigated in resonant cavity light emitting diodes (RCLEDs) and vertical cavity surface emitting lasers (VCSELs) below lasing threshold. These semiconductor photonic devices consisted of an optical gain region of quantum wells sandwiched between two distributed Bragg reflector (DBR) mirrors. Pump and probe lasers were injected into the devices to generate FWM. The dependence of FWM on bias current, pump laser power, and spectral and spatial separation between pump and probe lasers was investigated experimentally. A computer model of FWM based on the wave and carrier density equations was developed and agreed well …

Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts

Theses and Dissertations

MEMS (Micro-Electro-Mechanical Systems) micromirror devices can be used to control the phase of a propagating light wavefront, and in particular to correct aberrations that may be present in the wavefront, due to either atmospheric turbulence or any other type of fixed or time and space varying aberrations. In order to shorten the design cycle of MEMS micromirror devices, computer software is developed to create, from MEMS micromirror device design data, a numerical model of the MEMS device. The model is then used to compute the far field diffraction pattern of a wavefront reflected from the device, and to predict the …