Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 170461 - 170490 of 198032

Full-Text Articles in Engineering

Target Pose Estimation From Radar Data Using Adaptive Networks, Andrew W. Learn Mar 1999

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 …

Go to article

Analysis Of The Applicability Of Video Segmentation To Unmanned Aerial Vehicle Surveillance Video, Bradley L. Pyburn Mar 1999

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 …

Go to article

An Improved Asynchronous Implementation Of A Fast Fourier Transform Architecture For Space Applications, David J. Barnhart Mar 1999

An Improved Asynchronous Implementation Of A Fast Fourier Transform Architecture For Space Applications, David J. Barnhart

Theses and Dissertations

A second-generation fully asynchronous Fast Fourier Transform (FFT) processor for space applications is developed in this thesis. A high-performance patented FFT architecture invented by Suter and Stevens was used as the basis for a 16-point FFT (FFT-16) processor design. A brief derivation of the architecture, the asynchronous design methodologies used and space-based integrated circuit issues are presented. The Synopsys VLSI CAD system and a radiation tolerant design library developed by the Air Force Research Laboratory were used to implement the design. A critical building block of the FFT-16, the FFT-4, was fabricated as a cost-effective method to validate the cell …

Go to article

Integrated Ups/Ins Precision Approach Landing With M3ae Interference Avoidance, Stephan H. Chastain Mar 1999

Integrated Ups/Ins Precision Approach Landing With M3ae Interference Avoidance, Stephan H. Chastain

Theses and Dissertations

Several past research efforts have developed methods to take advantage of Global Positioning System (UPS) positioning and apply it to a precision landing system (PLS). There have been proposals to phase out the current Instrument Landing System (ILS) in favor of a more cost-efficient and effective system. Accomplishments have been made in detailing a system implementing an INS aided with differential UPS, a UPS pseudolite, and a radar altimeter to handle the critical PLS requirements. This research applies the newly developed Modified Multiple Model Adaptive Estimation (M3AE) architecture in an attempt to enhance the performance of a PLS in an …

Go to article

Radar Cross Section Enhancement Of Simple Targets, Brian J. Crothers Mar 1999

Radar Cross Section Enhancement Of Simple Targets, Brian J. Crothers

Theses and Dissertations

This thesis explores the use of periodic open slots as passive antenna scatterers to enhance the radar cross section of a simple target. Two slot geometries are considered, thin rectangular slots and circular slots. Targets are modified with slot arrays of various element size, spacings, numbers, and geometries. These geometries were later backed by a cavity in an attempt to further enhance RCS. Measurements were taken and the results were compared to target baselines, which are nothing more than the unslotted version of the same target. Moment method solutions were also computed for comparisons with measured results. Additionally, an analytical …

Go to article

Trade-Off Analysis Of Communications Capabilities Of Inter-Satellite Links, Andrew J. Feltman Mar 1999

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 …

Go to article

Non Co-Operative Detection Of Lpi/Lpd Signals Via Cyclic Spectral Analysis, Andrew M. Gillman Mar 1999

Non Co-Operative Detection Of Lpi/Lpd Signals Via Cyclic Spectral Analysis, Andrew M. Gillman

Theses and Dissertations

This research proposes and evaluates a novel technique for detecting LPI/LPD communication signals using a digital receiver primarily designed to detect radar signals, such as a Radar Warning Receiver (RWR) or an Electronic Support Measures (ESM) receiver. The proposed Cyclic Spectrum Analysis (CSA) receiver is a robust detector that takes advantage of the spectral correlation properties of second-order cyclostationary signals. A computationally efficient algorithm is used to estimate the Spectral Correlation Function (SCF). Using state-of-the-art FFT processing, it is expected that the proposed CSA receiver architecture could estimate the entire cyclic spectrum m approximately 0.6 ms. The estimate is then …

Go to article

Graphical User Interface And Microprocessor Control Enhancement Of A Pseudorandom Code Generator, John M. Kos Mar 1999

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 …

Go to article

Terrain Backscattering Coefficient Generator, Ricardo Mediavilla Mar 1999

Terrain Backscattering Coefficient Generator, Ricardo Mediavilla

Theses and Dissertations

Using already available data, a backscattering coefficient generator (BCG) for several types of terrain and measurement conditions is developed. The types of terrain are: (1) soils and rocks, (2) trees, (3) grasses, (4) shrubs, (5) short vegetation, (6) roads, (7) urban areas, (8) dry snow, and (9) wet snow. These data sets typically cover incidence angles ranging between 0 and 80 degrees where 0 is normal to the terrain. Measurement conditions are defined by: (1) incidence angle, (2) wave polarizations configuration (HH, HV, or VV), and (3) radar band (L, C, S, X, Ku, Ka, or W). The BCG output …

Go to article

The Effect Of Registration Errors On Tracking In A Networked Radar System, Bradley J. Mortenson Mar 1999

The Effect Of Registration Errors On Tracking In A Networked Radar System, Bradley J. Mortenson

Theses and Dissertations

To successfully combine information from distributed radar sensors, it is essential that each sensor be correctly referenced in a global coordinate system. If there are biases in the reported position of these sensors, the reported target position will also be biased and the ensuing global estimate of the target position will be degraded. Furthermore, any biases in range or azimuth measurements of these sensors will likewise be reflected in the degradation of global estimate of target position. Registration is the process of ensuring that these errors do not result in the creation of an additional redundant target when only a …

Go to article

Low Grazing Angle Terrain Backscattering Coefficient Generator, William N. O'Connor Mar 1999

Low Grazing Angle Terrain Backscattering Coefficient Generator, William N. O'Connor

Theses and Dissertations

A near-horizon probabilistic terrain backscatter coefficient generator is introduced, combining modified sea-state curves with Weibull-type probability density functions. A total of nine terrain type classifications (soils & rocks, trees, grasses, shrubs, short vegetation, roads, urban areas, dry snow, and wet snow) are supported, for seven radar bands (L, S, C, X, Ku, Ka, and W), and both linear (HH, VV) and cross (HV, VH) polarizations. The Weibull functions are based on measured sigma and match the published data. The functions also provide a probabilistic nature to the generator. Modified sea state curves are used in place of the Weibull functions …

Go to article

A Climatology-Based Model For Long-Term Prediction Of Radar Beam Refraction, Todd S. Pittman Mar 1999

A Climatology-Based Model For Long-Term Prediction Of Radar Beam Refraction, Todd S. Pittman

Theses and Dissertations

The National Air Intelligence Center, WPAFB, OH, needs more accurate predictions of radar beam refraction. A new mode was developed for this thesis replacing the standard atmosphere approach with raytracing and climatology. Usually a microwave radio beam bends towards the earth with a radius of curvature greater than the earth's surface. However, seasonal and climatic variations influence the bending, and at times create temperature or moisture inversions that redirect the energy along the earth's surface leaving radio holes where there is no coverage. This model uses iterative raytracing to determine the most direct path from radar to target through the …

Go to article

Antenna Gain Enhancement Using A Photonic Band Gap Reflector, Karl C. Schloer Mar 1999

Antenna Gain Enhancement Using A Photonic Band Gap Reflector, Karl C. Schloer

Theses and Dissertations

Scientists have long known that periodic structures can filter electromagnetic (EM) waves. In the last decade, extension of one- and two-dimensionally periodic structures into a third periodic dimension has produced photonic band gap (PBG) structures. A PBG structure is characterized by its omnidirectional stop band at a set of frequencies determined by the structure's periodicity and permittivity. In the present research, we investigate such a structure as an antenna reflector. We aim to develop a modeling approach that provides accurate computations of PBG behavior without relying on massively parallel processing. We also construct and measure the bulk reflection and transmission …

Go to article

Loop Gain Estimation For Adaptive Control, Jamey P. Sillence Mar 1999

Loop Gain Estimation For Adaptive Control, Jamey P. Sillence

Theses and Dissertations

The identification of a linear discrete-time control system's loop gain is addressed. The classical Kalman filter theory for state estimation in linear control systems is extended, and the control system's loop gain and state are jointly estimated. A rigorous analysis of the measurement situation under consideration yields explicit formulae for the loop gain's unbiased estimate and estimation error's covariance.

Go to article

Ultra-Wideband Tem Horns, Transient Arrays And Exponential Curves: A Fdtd Look, Troy S. Utton Mar 1999

Ultra-Wideband Tem Horns, Transient Arrays And Exponential Curves: A Fdtd Look, Troy S. Utton

Theses and Dissertations

This research investigates the possibility of applying exponentially curved conducting plates to single-element Transverse Electromagnetic (TEM) horns and their transient arrays to enhance the UWB characteristics already experienced by these radiators. The first part of this study demonstrates the Finite-Difference Time-Domain (FDTD) method's ability to duplicate experimental data, and establishes the baseline models used throughout the remainder of the research. The baseline models consist of the typical flat-triangle shaped conducting plates. The exponential taper models incorporate the exponential curves in the height, the width, and both the height and width directions. One, two- and four-element baseline configurations are compared to …

Go to article

Modulation Of Electrostatic Microelectromechanical Mirrors Using A Cmos Controller, Paul C. Rounsavall Mar 1999

Modulation Of Electrostatic Microelectromechanical Mirrors Using A Cmos Controller, Paul C. Rounsavall

Theses and Dissertations

Microelectromechanical Systems (MEMS) is a rapidly growing technology that lends itself particularly well to optical applications. An example of an optical MEMS device is the piston-action mirror that modulates the phase of reflected light. The phase of reflected light can be varied using thermal or electrostatic actuation to control the position of the mirror. In previous research, a modulation method to control thermally actuated mirrors was developed. This thesis presents the development, implementation, fabrication, and testing of a complimentary metal oxide semiconductor (CMOS) controller capable of directly interfacing between a digital system, such as a computer, and an electrostatically actuated …

Go to article

Application Of The Finite Element Method To The Scattering Of A Two-Dimensional, Semi-Infinite Periodic Structure, Perry N. Villanueva Mar 1999

Application Of The Finite Element Method To The Scattering Of A Two-Dimensional, Semi-Infinite Periodic Structure, Perry N. Villanueva

Theses and Dissertations

Infinite periodic structures have been studied heavily because of their efficient filtering capabilities. They generally exhibit sharp frequency roll-offs at the frequency band of interest. In the RF region of the electromagnetic spectrum, periodic structures find applications such as radomes and photonic bandgap materials. Most studies have been done with infinitely periodic arrays because it is convenient to collapse an infinite array into one representative period using Floquet Analysis. Truncating an infinite array introduces an edge and invalidates Floquet analysis over the entire array. This thesis formulates a Finite Element Method (FEM) solution of a semi-infinite periodic array consisting of …

Go to article

An Integrated Synthetic Aperture Radar/Global Positioning System/Inertial Navigation System For Target Geolocation Improvement, Brian J. Young Mar 1999

An Integrated Synthetic Aperture Radar/Global Positioning System/Inertial Navigation System For Target Geolocation Improvement, Brian J. Young

Theses and Dissertations

This thesis explores a potential integration technique to fuse information from an inertial navigation system (INS) and global positioning system (GPS) with synthetic aperture radar target measurements. Using Kalman filtering techniques, an INSIGPS/SAR integrated system was simulated in a single Kalman filter to analyze the SAR target geolocation accuracy benefits. Three different GPS receiver models were used in the integrated system: stand-alone (SGPS), differential (DGPS), and carrier-phase differential GPS (CPGPS). Each of these GPS models were integrated with a common INSISAR combination to determine the target geolocation accuarcy improvements due only to GPS receiver type. Thesis results show that SAR …

Go to article

Exploring The Management Of Outsourcing And The Determination Of Civil Engineering Minimum Manning Numbers In Order To Optimize Air Force Benefits, David J. Anason Mar 1999

Exploring The Management Of Outsourcing And The Determination Of Civil Engineering Minimum Manning Numbers In Order To Optimize Air Force Benefits, David J. Anason

Theses and Dissertations

This thesis investigates the relationship between peacetime and wartime tasks for Air Force Civil Engineering career fields in regard to outsourcing. Relevant literature in civilian sector outsourcing techniques is then studied to determine how they decide on what to outsource and what to keep insourced. Peacetime tasks performed by individual career fields are correlated with the wartime tasks to determine if there is any valuable wartime training gained from the completion of peacetime work orders. Several interviews completed with Air Force Civil Engineer readiness experts to evaluate an importance factor for each career field wartime mission. This importance factor and …

Go to article

Cost-Benefit Analysis Of Cosolvent Flushing To Treat Groundwater Contamination Source Areas, Stacey L. Anason Mar 1999

Cost-Benefit Analysis Of Cosolvent Flushing To Treat Groundwater Contamination Source Areas, Stacey L. Anason

Theses and Dissertations

Dense non-aqueous phase liquids (DNAPLs) in the zone beneath the water table can be a virtually permanent source of groundwater contamination that cannot be remediated by currently available technologies. Cosolvent flushing is a new technology that has the potential to remediate these sites and could pose a solution to the problem of DNAPL source areas. A computer model was developed to determine the cost and time to remediate an aquifer using cosolvent flushing. Included in the model is a module to calculate the costs of recycling the alcohol that is used as the cosolvent. The model was validated using site …

Go to article

Substrate Availability In Solid Waste Landfills, Brian D. Benter Mar 1999

Substrate Availability In Solid Waste Landfills, Brian D. Benter

Theses and Dissertations

Numerous models exist to both predict and represent the many biological activities that occur in the modern landfill. These different models use varying methods of characterizing what is happening, what is thought to happen, or what should be happening based on both empirical data and theoretical reasoning. The model presented here is an extension of the system dynamics model originally presented by Colborn in 1997. The revamped model presents a different perspective on what happens as solid organic waste is transformed to simpler substances. This new view involves a bacterial population performing hydrolysis whose growth is limited by the amount …

Go to article

Biodegradation Of Aircraft Deicing Fluid Components In Soil, Baron W. Burke Mar 1999

Biodegradation Of Aircraft Deicing Fluid Components In Soil, Baron W. Burke

Theses and Dissertations

Aircraft de-icing fluids (ADFs) are used worldwide to ensure safe aircraft operations. This research effort was conducted to analyze the biodegradation effects of two chemical components of ADFs, propylene glycol (PG) and tolyltriazole (TTA), in a high-clay soil. The research used four test methods; automated respirometry, high performance liquid chromatography (HPLC), microbial colony population counts (MCPC), and agar well diffusion tests (AWDT). The research was partitioned into two phases of investigation. Phase-one analyzed individual and combined ADF chemical components on uncontaminated soil. The presence of TTA, from 25 - 1,000 mg/kg, reduced the maximum respiration rate of 1,000 mg/kg PG …

Go to article

Textual Analysis Of Environmental Compliance Assessment Program Findings, Arthur L. Gepner Jr. Mar 1999

Textual Analysis Of Environmental Compliance Assessment Program Findings, Arthur L. Gepner Jr.

Theses and Dissertations

The United States Air Force (USAF) is committed to assessing environmental compliance; this is achieved in the USAF through the Environmental Compliance Assessment Management Program (ECAMP). These ECAMP audits are designed strictly to assess compliance performance at one point-in-time. They are not intended to assess underlying environmental management systems. This study provides insight into the USAF Environmental Management System (EMS) through a textual analysis of ECAMP data. The analysis discovers eleven categories that emerged from the data: performance, communication, documentation, coordination, training, guidance, notification, resource, human resource, material resource, and financial resource. These categories display a hierarchical relationship. This hierarchical …

Go to article

Expeditious Method For Estimating Cleanup Costs At Department Of Defense Installations In Korea, John M. Griffin Mar 1999

Expeditious Method For Estimating Cleanup Costs At Department Of Defense Installations In Korea, John M. Griffin

Theses and Dissertations

The purpose of this research was to develop and test a method that can be used to expeditiously estimate costs of hazardous waste site remediation at US DoD installations in Korea allowing decision-makers to formulate remediation strategy. This objective was addressed through answering the following questions: (1) What cost and time constraints do the decision-makers have in developing remediation cost estimates; (2) What degree of accuracy do the decision-makers require in cost estimates; (3) What estimating models are available for determining costs of remediation activities; (4) Have models been used to estimate remediation activities' costs at Korean installations; and (5) …

Go to article

The Determinants Of Locational Choice For Air Force Military Renters: Implications For Policy, Eldrick L. Hill Mar 1999

The Determinants Of Locational Choice For Air Force Military Renters: Implications For Policy, Eldrick L. Hill

Theses and Dissertations

Housing allowances and military family housing make up approximately $7 billion dollars of the budget for the Department of Defense (DoD). The military uses a Housing Market Analysis (HMA) to determine rental housing availability around its installations. This thesis describes and analyzes the locational choices of military renters. This thesis examines 16 bases in the continental U.S. using military and census data. It is concluded that the locational preferences of military renters vary inversely with distance from their duty location and this needs to be accounted for when assessing the availability of military rental housing. The implications of military renter …

Go to article

Optimal Pulsed Pumping Schedule Using Calculus Of Variation Methodology, Tay W. Johannes Mar 1999

Optimal Pulsed Pumping Schedule Using Calculus Of Variation Methodology, Tay W. Johannes

Theses and Dissertations

Application of a variational optimization technique has demonstrated the potential strength of pulsed pumping operations for use at existing pump-and-treat aquifer remediation sites. The optimized pulsed pumping technique has exhibited notable improvements in operational effectiveness over continuous pumping. The optimized pulsed pumping technique has also exhibited an advantage over uniform time intervals for pumping and resting cycles. The most important finding supports the potential for managing and improving pumping operations in the absence of complete knowledge of plume characteristics. An objective functional was selected to minimize mass of water removed and minimize the non-essential mass of contaminant removed. General forms …

Go to article

Individual Housing Choices Among Air Force Members, Michael J. Johnson Mar 1999

Individual Housing Choices Among Air Force Members, Michael J. Johnson

Theses and Dissertations

Air Force members have three different housing choices: live in MFH, rent in the local community, or buy a house in the local community. A set of six constructs (Housing Attributes, Safety, Pet Importance, Location, Military Housing Perception, and Community) that encompass members' considerations is developed and analyzed. The data was extracted from a survey that was specifically designed to illicit the relative importance of each construct during the housing decision making process. Each construct was measured using a Likert scale score. Statistical analysis was performed to determine the overall Likert mean score for each construct. Using the Likert mean …

Go to article

Expeditious Methods For Site Characterization And Risk Assessment At Department Of Defense Hazardous Waste Sites In The Republic Of Korea, Dean H. Hartman Mar 1999

Expeditious Methods For Site Characterization And Risk Assessment At Department Of Defense Hazardous Waste Sites In The Republic Of Korea, Dean H. Hartman

Theses and Dissertations

The overall goal of this research was to provide Department of Defense (DoD) decision-makers in the Republic of Korea (ROK) with preferred innovative site characterization technologies and risk assessment methods to meet their needs in obtaining hazardous waste site data and then prioritizing those sites for remediation based upon risk. The study examined the following: primary sources and types of existing contamination at DoD installations in the ROK; available site characterization data; criteria to be used in selecting innovative site characterization technologies; costs and capabilities of the innovative site characterization technologies; risk assessment or risk-based corrective action (RBCA) methods available …

Go to article

Development Of Site Characterization Simulator, Neil W. Kassel Mar 1999

Development Of Site Characterization Simulator, Neil W. Kassel

Theses and Dissertations

The purpose of this study was to develop a tool for Remedial Project Managers (RPMs) to learn and practice the site characterization process. One of the key difficulties encountered by RPMs during site characterization is the need to develop a model of the site based on limited data. These limited data are used to determine parameters that describe hydrogeologic and contaminant properties (aquifer hydraulic conductivity, contaminant concentration, etc.) and are obtained using sampling techniques that interrogate a very small volume, usually much smaller than node spacing of the computer model used to simulate site conditions. The value of the parameter …

Go to article

Sorption Of The Aircraft Deicing Fluid Component Methyl-Benzotriazole In Soil, David L. Kellner Mar 1999

Sorption Of The Aircraft Deicing Fluid Component Methyl-Benzotriazole In Soil, David L. Kellner

Theses and Dissertations

The air transportation industry requires deicing/anti-icing (ADAF) fluids to maintain flight operations in cold weather conditions. Additives to the ADAF aid in the performance of these agents. Approximately 52M liters of concentrated aircraft deicing fluid are used in North America per year in an attempt to correct this safety problem. Among the additives to ADAF are corrosion inhibitors flame retardants, wetting agents, and thickening agents. Some of these agents are known to be toxic to microorganisms. Identification of the transport processes of these agents in the environment is a necessary first step to understanding how to remediate ADAF. Methyl-Benzotriazole (MeBT) …

Go to article

First Prev Next Last