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Articles 2041 - 2070 of 2678
Full-Text Articles in Physical Sciences and Mathematics
Generating Executable Code From Formal Specifications Of Primitive Objects, Travis W. Tankersley
Generating Executable Code From Formal Specifications Of Primitive Objects, Travis W. Tankersley
Theses and Dissertations
The concept of developing a model for producing compilable and executable code from formal software specifications has long been a goal of software engineers. Previous research at the Air Force Institute of Technology (AFIT) has been focused on specification and domain analysis. An analysis model is populated using specifications written in Z. Then, a set of preliminary design transforms refines the specification in the analysis model. This research bridges the gap between analysis and design, allowing source code to be produced from formal specifications of primitive objects using transformational programming. The contribution of this thesis is to transform the analysis …
A Refinement And Cross-Validation Of The Special Sensor Microwave Imager (Ssm/I) Calibration-Validation (Cv) Brightness Temperature Algorithm, Mark R. Adair
Theses and Dissertations
The Air Force Weather Agency (AFWA) currently uses an algorithm to calculate surface temperatures from microwave observations taken by the Special Sensor Microwave Imager (SSM/I) aboard the orbiting platforms of the Defense Meteorological Satellite Program (DMSP). This algorithm, called the Calibration-Validation (CV) algorithm, used multiple linear regression to calculate coefficients relating microwave brightness temperatures and land surface temperatures. Because the coefficients in this algorithm do not take into account the identity of the individual satellite, the question arose whether this assumption was valid. This thesis used multiple linear regression, stepwise linear regression, and qualitative regression on 3700 data sets from …
Estimating The Height Of The Planetary Boundary Layer For Diffusion-Transport Models: A Four Algorithm Comparison, Robert L. Russ
Estimating The Height Of The Planetary Boundary Layer For Diffusion-Transport Models: A Four Algorithm Comparison, Robert L. Russ
Theses and Dissertations
Diffusion-Transport (D-T) modeling is a branch of numerical weather prediction concerned with eddy diffusion of particulate pollutant plumes and their transport by the wind. When conducting D-T modeling, establishing the height of the planetary boundary layer (PBL) is crucial to defining the vertical bounds within which a plume can become thoroughly mixed. The PBL can be deduced from observations or model simulation. Three sounding analysis PBL algorithms were considered - the Potential Instability Mixing Depth (PIMIX), Potential Temperature (POTEMP), and Gradient Richardson Number (RICH) algorithms. A turbulent kinetic energy (TKE) based PBL algorithm was also evaluated. The purpose of this …
Forecasting Downdraft Wind Speeds Associated With Airmass Thunderstorms For Peterson Air Force Base, Colorado, Using The Wsr-88d, Travis A. Steen
Forecasting Downdraft Wind Speeds Associated With Airmass Thunderstorms For Peterson Air Force Base, Colorado, Using The Wsr-88d, Travis A. Steen
Theses and Dissertations
During the period Jun-Aug 96, four Air Force installations suffered over $4.8 million in damage from convective winds. During the same summer, Air Force Space Command units issued nearly 65% of their weather warnings for convective winds, making the forecasting of convective winds the most frequent challenge to forecasters. This thesis seeks to assist Air Force forecasters at Peterson Air Force Base (PAFB), Colorado, in forecasting airmass thunderstorm downdraft wind speeds using the Weather Surveillance Radar-1988 Doppler (WSR-88D). To accomplish this purpose, several existing potential downdraft wind speed prediction techniques were evaluated against the observed wind speeds of nineteen airmass …
A New Sequential Goodness Of Fit Test For The Three-Parameter Gamma Distribution With Known Shape Based On Skewness And Kurtosis, Chil Ho Park
Theses and Dissertations
This research presents a new sequential goodness of fit test for the three-parameter gamma distribution with a known shape. The test is accomplished by employing two new tests, sample skewness and sample kurtosis, sequentially as test statistics. Unlike the typical goodness of fit test, using parameter estimation methods such as maximum likelihood estimation and minimum distance estimation, this test using the two test statistics above does not involve a substantial degree of computational complexity. Large Monte Carlo simulation has been used to determine critical values and overall significance levels for all combinations of the two tests, and to conduct extensive …
Protein Structure Prediction Using Parallel Linkage Investigating Genetic Algorithms, Karl R. Deerman
Protein Structure Prediction Using Parallel Linkage Investigating Genetic Algorithms, Karl R. Deerman
Theses and Dissertations
AFIT has had a long-standing interest in solving the protein structure prediction (PSP) problem. The PSP problem is an intractable problem that if "solved" can lead to revolutionary new techniques for everything from the development of new medicines to optical computer switches. The challenge is to find a reliable and consistent method of predicting the 3-dimensional structure of a protein given its defining sequence of amino acids. PSP is primarily concerned with predicting the tertiary protein structure without regards to how the protein came to this folded state. The tertiary structure determines the protein's functionality.
Methodology For Application Design Using Information Dissemination And Active Database Technologies, Robert H. Hartz
Methodology For Application Design Using Information Dissemination And Active Database Technologies, Robert H. Hartz
Theses and Dissertations
In dynamic data environments, the large volume of transactions requires flexible control structures to effectively balance the flow of information between producers and consumers. Information dissemination-based systems, using both data push and pull delivery mechanisms, provide a possible scalable solution for data-intensive applications. In this research, a methodology is proposed to capture information dissemination design features in the form of active database rules to effectively control dynamic data applications. As part of this design methodology, information distribution properties are analyzed, data dissemination mechanisms are transformed into an active rule framework, and the desired reactive behavior is achieved through rule customization. …
A Constructive Induction Approach To Computer Immunology, Kelley J. Cardinale, Hugh M. O'Donnell
A Constructive Induction Approach To Computer Immunology, Kelley J. Cardinale, Hugh M. O'Donnell
Theses and Dissertations
With the increasing birth rate of new viruses and the rise in interconnectivity and interoperability among computers, the burden of detecting and destroying computer viruses is severe. This research integrated four domains: computer virus detection, human immunology, computer immunology and an automated form of machine learning called constructive induction. First, a Computer Health System, based on the public health system, was defined to improve the 'global' approach to computer virus protection. Second, a computer immune model, based on the human immune system, was defined to improve the 'local' approach to virus detection. Third, the detection component of this computer immune …
Validation Of The Gallagher Protonospheric Model, Kelly M. Law
Validation Of The Gallagher Protonospheric Model, Kelly M. Law
Theses and Dissertations
Ionospheric models are used in many systems throughout the Department of Defense: for example, they are useful in correcting range errors in radio signals. However, correction models don't incorporate the protonosphere, the torus-shaped plasma volume above the ionosphere. The Gallagher Protonospheric Model, recently incorporated into the Parameterized Ionospheric Model 1.7 (PIM 1.7), was validated against protonospheric total electron content (PTEC) measurements made by the GPS system. Gallagher model calculations of slant PTEC for Pittsburgh ground station looking south with a raypath at an elevation of 26 degrees were compared against GPS PTEC measurements for the same configuration derived from the …
Electrical Characterization Of Ion-Implanted 4h-Silicon Carbide, Christian P. Morath
Electrical Characterization Of Ion-Implanted 4h-Silicon Carbide, Christian P. Morath
Theses and Dissertations
Electrical characterization has been performed on ion-implanted p-type 4H-SiC to assess the activation efficiency and implantation-related damage recrystallization with the intention of developing an implantation/annealing scheme. Low doped (Na - Nd = 5x10(exp 15)/cu cm) epitaxial p-type layers grown by MOCVD were implanted with Al or B at doses ranging from 1x10(exp 13) to 1x10(exp 14)/sq cm at room temperature or 500 deg. C. The electrical technique of Temperature Dependent Hall Effect (TDHE) indicated that Al and B act as shallow acceptors 4H-SiC with ionization energies of ^252 and ^285 meV, respectively. The highest activation efficiency for Al and B …
Band Structure Anisotropy In Semiconductor Quantum Wells, Steven J. Novotny
Band Structure Anisotropy In Semiconductor Quantum Wells, Steven J. Novotny
Theses and Dissertations
The focus of this research is an investigation of energy band anisotropy in simple quantum well structures. This anisotropy results from the asymmetry of the periodic potential within the crystal lattice. For sufficiently high doping levels, band structure anisotropy is expected to play an important role in the evaluation of the electronic and optical properties of the quantum well structures. The analysis uses a model based on a 6x6 Luttinger-Kohn k.p approach for bulk material valence band structure together with the Envelope Function Approximation. The model is used to analyze Si/SiGe, AlGaAs/GaAs, and GaAs/InGaAs quantum wells for the 001 and …
Optimization Of A Multilayer Photothermal Sensor For Infrared Spectroscopy, Janine O.J. Wiggins
Optimization Of A Multilayer Photothermal Sensor For Infrared Spectroscopy, Janine O.J. Wiggins
Theses and Dissertations
Tri-layer thermal diffusion modeling was applied to the optimization of a multi-layer reed sensor for use in a photothermal infrared detector. The multi-layer reed sensor deflects in response to increased temperature. Deflection, of angstroms or larger, is measured using an atomic force microscope. A newly developed thermal diffusion model for three layer reeds was combined with an existing two-layer cantilever model, in order to explore the effects of length, operating frequency, and layer thickness on signal to noise ratio. Model behavior is presented, and compared to laboratory results.
An Interactive Tool For Refining Software Specifications From A Formal Domain Model, Gary L. Anderson
An Interactive Tool For Refining Software Specifications From A Formal Domain Model, Gary L. Anderson
Theses and Dissertations
This work examines the process for refining a software specification from a formal object-oriented domain model. This process was implemented with interactive software to demonstrate the feasibility and benefits of automating what has been a tedious and often error-prone manual task. The refinement process operates within the framework of a larger Knowledge-Based Software Engineering system. A generic object-oriented representation is used to store a domain model, which allows the specification tool to access, select, and manipulate the required objects to form a customized specification. The specification is also stored as an object-oriented model, which in turn can be accessed by …
Target Pose Estimation From Radar Data Using Adaptive Networks, Andrew W. Learn
Target Pose Estimation From Radar Data Using Adaptive Networks, Andrew W. Learn
Theses and Dissertations
his research investigates and extends recent work by J.C. Principe at the University of Florida in target pose estimation using adaptive networks. First, Principe's technique is successfully extended to estimate both azimuth and elevation using SAR images. A network trained and tested using MSTAR data yields mean errors of less than six degrees in azimuth and five degrees in elevation. Second, the technique is applied to high-range resolution radar (HRR) signatures. Ground target (azimuth only) testing yields mean errors of less than 11 degrees for most classes. Air target testing for networks trained and tested on the same aircraft class …
Extensible Multi-Agent System For Heterogeneous Database Association Rule Mining And Unification, Christopher G. Marks
Extensible Multi-Agent System For Heterogeneous Database Association Rule Mining And Unification, Christopher G. Marks
Theses and Dissertations
The Probabilities, Expert System, Knowledge, and Inference (PESKI) System uses the data mining of association rules to fill incompleteness in the knowledge of an expert system. The rules are mined from transactional data sources and then incorporated using an existing link to PESKI. One method of providing a system that will easily allow new data sources to be added is using an information gathering agent-based system. This research first develops a methodology for designing and creating a multi-agent system. It then applies this methodology to design a platform independent means of data mining data sources of any format. The use …
A Structured Approach To Software Tool Integration, Penelope A. Noe
A Structured Approach To Software Tool Integration, Penelope A. Noe
Theses and Dissertations
As the trend towards commercial off-the-shelf (COTS) software continues, civilian companies and government agencies alike are battling with the challenge of making multiple software packages and applications work together. Many of these companies and agencies have attempted to integrate the software tools to form a coherent system that satisfies their goals, often without the use of a step by step approach guiding the effort. Many researchers in the field of software tool integration have determined the areas that need to be addressed when tools are integrated. Some researchers have developed and expanded upon a theoretical model for integration. This model …
Analysis Of The Applicability Of Video Segmentation To Unmanned Aerial Vehicle Surveillance Video, Bradley L. Pyburn
Analysis Of The Applicability Of Video Segmentation To Unmanned Aerial Vehicle Surveillance Video, Bradley L. Pyburn
Theses and Dissertations
The focus of this research is to determine if applying edge detection segmentation (proposed by Ramin Zabih, Justin Miller, and Kevin Mai) to Unmanned Aerial Vehicle (UAV) video footage can provide meaningful segments for database storage and retrieval. The edge detection segmentation algorithm is applied to fifty-four UAV video sequences containing visual effects such as abrupt camera changes, camera zooms, motion (rapid and gradual), and cloud cover while varying the frame rate from 5 fps to 30 fps. An analysis of the results is performed to compare actual versus expected outcomes, similar sequences, and scenes with motion, along with explaining …
Evaluation Of Barnes' Method And Kriging For Estimating The Low Level Wind Field, Michael W. Engel
Evaluation Of Barnes' Method And Kriging For Estimating The Low Level Wind Field, Michael W. Engel
Theses and Dissertations
This thesis evaluates two different methods of estimating a three dimensional wind field based upon a limited number of irregularly-spaced observations. This work was performed for the 45th Weather Squadron to determine how well the two methods worked and their potential for use in a visualization program. The two methods evaluated were Barnes' method and a method called Kriging, which is commonly used in geostatistics. Both of these estimation techniques were implemented and then evaluated to determine how accurate the estimates were that they created. The methods' accuracies were determined by withholding an observation from the observed wind field data …
Using The Wsr-88d To Forecast Downburst Winds At Cape Canaveral Air Station And The Kennedy Space Center (Ccas/Ksc), Gerald D. Sullivan Jr.
Using The Wsr-88d To Forecast Downburst Winds At Cape Canaveral Air Station And The Kennedy Space Center (Ccas/Ksc), Gerald D. Sullivan Jr.
Theses and Dissertations
The 45 Weather Squadron is tasked with providing several convective wind warnings in support of the U. S. Space Program. The forecasters use a radar-based forecast technique to determine if a thunderstorm has the potential to produce a gust that meets warning criteria. This technique, the Echo Top/Vertically Integrated Liquid Wind Gust Potential (ET/VIL WGP), has not previously been evaluated for use in the Cape Canaveral Air Station and Kennedy Space Center (CCAS/KSC) locale. Additionally, there are two other radar-based forecast techniques that required evaluation for possible inclusion into the 45 WS forecast process. These are the Maximum Reflectivity / …
An Efficient Gps Position Determination Algorithm, Carlos R. Colon
An Efficient Gps Position Determination Algorithm, Carlos R. Colon
Theses and Dissertations
The use of detect, or closed-form solutions of the trilateration equations used to obtain the position fix in GPS receivers is investigated. The paper is concerned with the development of an efficient new position determination algorithm that uses the closed-form solution of the trilateration equations and works in the presence of pseudorange measurement noise and for an arbitrary number of satellites. in addition, an initial position guess is not required and good estimation performance is achieved even under high GDOP conditions. A two step GPS position determination algorithm which 1) entails the solution of a linear regression problem and, 2) …
Graphical User Interface And Microprocessor Control Enhancement Of A Pseudorandom Code Generator, John M. Kos
Graphical User Interface And Microprocessor Control Enhancement Of A Pseudorandom Code Generator, John M. Kos
Theses and Dissertations
Modern digital communication techniques often require the generation of pseudorandom numbers or sequences. The ability to quickly and easily produce various codes such as maximal length codes, Gold codes, Jet Propulsion Laboratory ranging codes, syncopated codes, and non-linear codes in a laboratory environment is essential. This thesis addresses the issue of providing automated computer control to previously built, manually controlled hardware incorporating the Stanford Telecom STEL-1032 Pseudo-Random Number (PRN) Coder. By incorporating a microcontroller into existing hardware, the STEL-1032 can now be conveniently controlled from a MATLAB Graphical User Interface (GUI). The user can quickly create, save, and recall various …
Active Multispectral Band Selection And Reflectance Measurement System, Bradley D. Rennich
Active Multispectral Band Selection And Reflectance Measurement System, Bradley D. Rennich
Theses and Dissertations
Due to system design requirements, an active multispectral laser radar system may be limited in the number of spectral bands that can be integrated into the system. To aid in the selection of these bands, a novel multispectral band selection technique is presented based on the cross-correlation of the material class reflectance spectra over a wavelength range of 1 - 5 microns. The algorithm uses directional hemispherical reflectance data from the Nonconventional Exploitation Factors database to select a number of spectral bands for classification purposes. Because the target material spectral reflectance is so important to the performance of an active …
A New Sequential Goodness-Of-Fit Test For A Family Of Two Parameter Gamma Distributions With Known Shape Based On Skewness And Q-Statistic, Jae Suk Park
Theses and Dissertations
The objective of this research is to develop a new goodness-of-fit test for the gamma distribution. The gamma distribution is widely used for reliability and failure time estimations in the real world. Several methods to measure the fit of data to a hypothesized distribution are commonly used such as the chi-squared test, and Anderson- Darling test. The most important aspect of these tests is how well the results reflect the distribution family. This research will use the sequential test with skewness and Q- statistic as test statistics for fitting a gamma distribution. The main idea of a sequential test is …
Characterization Of The Double Scatter Spectrum In Multiplexed Compton Scatter Tomography, David W. Gerts
Characterization Of The Double Scatter Spectrum In Multiplexed Compton Scatter Tomography, David W. Gerts
Theses and Dissertations
The Multiplexed Compton Scatter Tomograph (MCST) uses single back-scattered photons to image electron density in aluminum. A source of error in this imaging technique is the presence of multiple scatters. This thesis studies the double scatter spectrum as an approximation of the multiple scatter spectrum. A deterministic code called Monte Carlo Double Scatter (MOCADS) was developed to investigate the double scatter spectrum. The code includes calculations of the Rayleigh scatter, Compton scatter, Doppler broadening effects of the spectrum, and polarization effects following the Compton scatter. The Doppler broadening portion of the code was validated by a deterministic code called Scatgram. …
Laser Beam Combining And Cleanup Via Stimulated Brillouin Scattering In Multi-Mode Optical Fibers, Blake C. Rodgers
Laser Beam Combining And Cleanup Via Stimulated Brillouin Scattering In Multi-Mode Optical Fibers, Blake C. Rodgers
Theses and Dissertations
The main objective of this thesis was to demonstrate the feasibility of combining and cleaning up multiple laser beams via Stimulated Brillouin Scattering (SBS) in a multi-mode optical fiber. Beam combining via SBS in an optical fiber is of interest because of the low SBS threshold power in an optical fiber allowing low power diode laser beams to be combined into one high power beam. SBS theory and some of the important historical results are described briefly. The experimental results clearly indicate that SBS in multi-mode optical fiber can indeed combine laser beams and clean up the beams at the …
A Java Based Human Computer Interface For A Uav Decision Support Tool Using Conformal Mapping, Randy A. Flood
A Java Based Human Computer Interface For A Uav Decision Support Tool Using Conformal Mapping, Randy A. Flood
Theses and Dissertations
This paper describes the development of the Human Computer Interface (HCI) for a Decision Support System for routing Unmanned Aerial Vehicles (UAVs). This problem is a multi-vehicle routing problem with time-windows. Because of the unique nature of UAVs, a tool is needed to support dynamic re-routing. We solve the problem in two ways. First, we create a UAV Decision Support Tool (UAV DST) that uses a set of Java software objects to display maps and convert between latitude-longitude coordinates and x-y coordinates. Secondly, this library provides the ability for the user to dynamically reoptimize large UAV routing problems through a …
Trade-Off Analysis Of Communications Capabilities Of Inter-Satellite Links, Andrew J. Feltman
Trade-Off Analysis Of Communications Capabilities Of Inter-Satellite Links, Andrew J. Feltman
Theses and Dissertations
This thesis designs, develops, and uses software Graphical User Interfaces (GUIs) to analyze the communications capabilities of Radio Frequency (RF) Inter-Satellite Links (ISLs). The GUIs are geared towards analyzing the proposed ISLs of the Discoverer II program, but are general enough to permit analysis of any free-space RF ISLs. Discoverer II is a demonstration program of low-earth orbiting satellites and is primarily focused on satellite-based sensor technology. This thesis shows RF ISLs can meet the program requirement to broadcast the sensor data back to CONUS in near-real-time. The GUIs operate in real-time and explore trade-offs in the communications capability by …
Improving Cape Canaveral's Next-Day Thunderstorm Forecasting Using A Meso-Eta Model-Based Index, John C. Crane
Improving Cape Canaveral's Next-Day Thunderstorm Forecasting Using A Meso-Eta Model-Based Index, John C. Crane
Theses and Dissertations
Reliable thunderstorm forecasts are essential to safety and resource protection at Cape Canaveral. Current methods of forecasting day-2 thunderstorms provide little improvement over forecasting by persistence alone and are therefore in need of replacement. This research focused on using the mesoscale eta model to develop an index for improved forecasting of day-2 thunderstorms. Logistic regression techniques were used to regress the occurrence of a thunderstorm at Cape Canaveral against day-2 forecast variables output, or derived, from the mesoscale eta model. Accuracy and bias scores were calculated for the forecasts made by the regression equations, and the forecast results were compared …
Survey Of Military Applications For Fourier Transform Infrared (Ftir) Spectroscopy, Robert G. Hauser
Survey Of Military Applications For Fourier Transform Infrared (Ftir) Spectroscopy, Robert G. Hauser
Theses and Dissertations
This paper surveyed four potential military uses for a Fourier Transform Infrared (FTIR) Spectrometer. A physical method to retrieve vertical atmospheric temperature profiles using a least-squares solution on atmospheric radiance observed at the surface in the 4.3-micrometer carbon dioxide absorption band was analyzed. The method was not successful. Weighting functions, calculated from the surface looking up, were a maximum at the surface, so no unique solution for temperature retrieval by height was determined. Observed atmospheric radiance measurements were compared with radiance calculated using the Moderate Resolution Transmittance Code (MODTRAN). Qualitative comparison showed spectral features of observed and calculated radiance plots …
Collisional Effects In The Absorption Spectra Of The Oxygen A Band And Nitric Oxide Fundamental Band, Robert S. Pope
Collisional Effects In The Absorption Spectra Of The Oxygen A Band And Nitric Oxide Fundamental Band, Robert S. Pope
Theses and Dissertations
Fourier transform spectroscopy was used to measure pressure broadening coefficients in the absorption spectra of both the oxygen A band and the nitric oxide fundamental band. Oxygen spectra were recorded with O2, N2, CO, CO2, SF6 and noble gas collision partners, while nitric oxide spectra were recorded using noble gas collision partners. Pressure broadening coefficients were determined in the P and R branches for every resolved line for each of the fifteen collision pairs studied. In addition, broadening coefficients and qualitative evidence of line coupling were found for the Q branch of NO …