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Theses and Dissertations

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Articles 7891 - 7920 of 11510

Full-Text Articles in Engineering

Deeply-Integrated Feature Tracking For Embedded Navigation, Jeffery R. Gray Mar 2009

Deeply-Integrated Feature Tracking For Embedded Navigation, Jeffery R. Gray

Theses and Dissertations

The Air Force Institute of Technology (AFIT) is investigating techniques to improve aircraft navigation using low-cost imaging and inertial sensors. Stationary features tracked within the image are used to improve the inertial navigation estimate. These features are tracked using a correspondence search between frames. Previous research investigated aiding these correspondence searches using inertial measurements (i.e., stochastic projection). While this research demonstrated the benefits of further sensor integration, it still relied on robust feature descriptors (e.g., SIFT or SURF) to obtain a reliable correspondence match in the presence of rotation and scale changes. Unfortunately, these robust feature extraction algorithms are computationally …

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Waypoint Generation Based On Sensor Aimpoint, Shannon M. Farrell Mar 2009

Waypoint Generation Based On Sensor Aimpoint, Shannon M. Farrell

Theses and Dissertations

Secretary of Defense Robert M. Gates has emphasized a need for a greater number of intelligence, surveillance, and reconnaissance (ISR) assets to support combatant commanders and military operations globally. Unmanned systems, especially MAVs, used as ISR platforms provide the ability to maintain covertness during missions and help reduce the risk to human life. This research develops waypoint generation algorithms required to keep a point of interest (POI) in the field of view (FOV) of a fixed sensor on a micro air vehicle (MAV) in the presence of a constant wind.
Fixed sensors, while cheaper and less prone to mechanical failure …

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A Finite Element Evaluation Of An Experiment Related To Coating Damping Properties, Armando Deleon Mar 2009

A Finite Element Evaluation Of An Experiment Related To Coating Damping Properties, Armando Deleon

Theses and Dissertations

Typically turbine engine blades gain protection from thermal damage by the use of hard coatings, such as magnesium aluminate spinel. Known as Thermal Barrier Coatings (TBC's), they have material properties that include several nonlinearities. These TBC's create damping primarily due to their nonlinear dissipation of energy. In order to effectively represent their damping properties, it is necessary to create a method which combines experimentation and analysis. Previous work has shown the need for a beam bounded and loaded in such a fashion that external support energy dissipation functions i.e. boundary conditions and aerodynamics are eliminated. Thus, a new experimental apparatus …

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Architecting Human Operator Trust In Automation To Improve System Effectiveness In Multiple Unmanned Aerial Vehicles (Uav), Eric A. Cring, Adam G. Lenfestey Mar 2009

Architecting Human Operator Trust In Automation To Improve System Effectiveness In Multiple Unmanned Aerial Vehicles (Uav), Eric A. Cring, Adam G. Lenfestey

Theses and Dissertations

Current Unmanned Aerial System (UAS) designs require multiple operators for each vehicle, partly due to imperfect automation matched with the complex operational environment. This study examines the effectiveness of future UAS automation by explicitly addressing the human/machine trust relationship during system architecting. A pedigreed engineering model of trust between human and machine was developed and applied to a laboratory-developed micro-UAS for Special Operations. This unprecedented investigation answered three primary questions. Can previous research be used to create a useful trust model for systems engineering? How can trust be considered explicitly within the DoD Architecture Framework? Can the utility of architecting …

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Host-Based Multivariate Statistical Computer Operating Process Anomaly Intrusion Detection System (Paids), Glen R. Shilland Mar 2009

Host-Based Multivariate Statistical Computer Operating Process Anomaly Intrusion Detection System (Paids), Glen R. Shilland

Theses and Dissertations

No abstract provided.

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Project Scheduling To Maximize Positive Impacts Of Reconstruction Operations, Andrew D. Chaney Mar 2009

Project Scheduling To Maximize Positive Impacts Of Reconstruction Operations, Andrew D. Chaney

Theses and Dissertations

Since the decline of the Cold War, the risk of major conflict between powerful industrialized nations has significantly decreased. Insecurity in the twenty-first century is forecast to arise rather from the debris of imploding states. Such situations may require intervention | military or otherwise | by concerned states, and the frequency with which these interventions occur is increasing. To meet this new operational challenge, the US military must adapt its planning procedures to account for Security, Stabilization, Transition, and Reconstruction Operations (SSTRO). This research develops a project scheduling based framework for post-conflict reconstruction that prioritizes and schedules reconstruction activities in …

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An Advanced Tabu Search Approach To Solving The Mixed Payload Airlift Load Planning Problem, Robert Larry Nance Mar 2009

An Advanced Tabu Search Approach To Solving The Mixed Payload Airlift Load Planning Problem, Robert Larry Nance

Theses and Dissertations

This paper presents a new tabu search based two-dimensional bin packing algorithm which produces high quality solutions to the Mixed Payload Airlift Load Planning (MPALP) problem using C-5 and C-17 aircraft. This algorithm, called Mixed Payload Airlift Load Planning Tabu Search (MPALPTS), surpasses previous research conducted in this area because, in addition to pure pallet cargo loads, MPALPTS can accommodate rolling stock cargo (i.e. tanks, trucks, HMMMVs, etc.) while still maintaining aircraft feasibility with respect to aircraft center of balance, mandatory cargo separations, aircraft floor structural limitations, etc. Furthermore, while this research is currently restricted to C-5 and C-17 aircraft, …

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Value-Driven Enterprise Architecture Score: Evaluation Applied To Joint Force Protection Future State Design, Larry D. Cotton, Gary A. Haase Mar 2009

Value-Driven Enterprise Architecture Score: Evaluation Applied To Joint Force Protection Future State Design, Larry D. Cotton, Gary A. Haase

Theses and Dissertations

This research presents a methodology to evaluate the quality of a system's architecture using principles drawn from Value-Focused Thinking (VFT) and resulting in a Value-Driven Enterprise Architecture Score (VDEA-Score). This is an overall numerical architecture quality score useful to a system's management team to identify the advantages and disadvantages of a system design and associated architecture documentation or to track its quality across discrete evaluation epochs. This effort determined which aspects of the architecture are most valuable to the stakeholder in the areas of (1) the system effectiveness values (quality of the instantiated system being represented and its ability to …

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Using Multiple Robust Parameter Design Techniques To Improve Hyperspectral Anomaly Detection Algorithm Performance, Matthew T. Davis Mar 2009

Using Multiple Robust Parameter Design Techniques To Improve Hyperspectral Anomaly Detection Algorithm Performance, Matthew T. Davis

Theses and Dissertations

Detecting and identifying objects of interest is the goal of all remote sensing. New advances, specifically in hyperspectral imaging technology have provided the analyst with immense amounts of data requiring evaluation. Several filtering techniques or anomaly detection algorithms have been proposed. However, most new algorithms are insufficiently verified to be robust to the broad range of hyperspectral data being made available. One such algorithm, AutoGAD, is tested here via two separate robust parameter design techniques to determine optimal parameters for consistent performance on a range of data with large attribute variances. Additionally, the results of the two techniques are compared …

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Misregistration In Adaptive Optics Systems, Nathan D. Engstrom Mar 2009

Misregistration In Adaptive Optics Systems, Nathan D. Engstrom

Theses and Dissertations

An adaptive optics (AO) system is most effective when there is a known alignment between the wave front sensor (WFS) and the deformable mirror (DM). Misregistration is the term for the unknown alignment between the WFS and DM. Misregistration degrades system performance and can make the system unstable. An AO system uses a reconstruction matrix to transform WFS measurements into DM commands. A standard AO system uses a model reconstruction matrix that assumes perfect registration between the WFS and DM. The object of this research is to mitigate the negative effects of misregistration by using offline WFS measurements to create …

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Image Processing For Multiple-Target Tracking On A Graphics Processing Unit, Michael A. Tanner Mar 2009

Image Processing For Multiple-Target Tracking On A Graphics Processing Unit, Michael A. Tanner

Theses and Dissertations

Multiple-target tracking (MTT) systems have been implemented on many different platforms, however these solutions are often expensive and have long development times. Such MTT implementations require custom hardware, yet offer very little flexibility with ever changing data sets and target tracking requirements. This research explores how to supplement and enhance MTT performance with an existing graphics processing unit (GPU) on a general computing platform. Typical computers are already equipped with powerful GPUs to support various games and multimedia applications. However, such GPUs are not currently being used in desktop MTT applications. This research explores if and how a GPU can …

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The Modular Clock Algorithm For Blind Rendezvous, Nicholas C. Theis Mar 2009

The Modular Clock Algorithm For Blind Rendezvous, Nicholas C. Theis

Theses and Dissertations

This thesis examines the problem in initializing communications whereby cognitive radios need to find common spectrum with other cognitive radios, a process known as frequency rendezvous. It examines the rendezvous problem as it exists in a dynamic spectrum access cognitive network. Specifically, it addresses the problem of rendezvous in an infrastructureless environment. A new algorithm, the modular clock algorithm, is developed and analyzed as a solution for the simple rendezvous environment model, coupled with a modified version for environment models with less information. The thesis includes a taxonomy of commonly used environment models, and analysis of previous efforts to solve …

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Probabilistic Estimation Of Rare Random Collisions In 3-Space, Timothy Holzmann Mar 2009

Probabilistic Estimation Of Rare Random Collisions In 3-Space, Timothy Holzmann

Theses and Dissertations

A study of risk assessment for artillery fire randomly colliding with fixed wing aircraft is presented. The research lends itself to a general study of collision models. Current models of object collisions fall under one of three categories: the historical model, the gas particle model, and the satellite model. These three vary in data requirements and mathematical representation of the impact event. The gas particle model is selected for its flexibility and robust estimation. However, current mathematical development in the literature does not include certain spatial and dynamic components necessary for a general encounter (collision) model. These are derived in …

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A Cost Assessment Of The Dayton Public Schools Vehicle Routing Problem, Frankie L. Woods Jr. Mar 2009

A Cost Assessment Of The Dayton Public Schools Vehicle Routing Problem, Frankie L. Woods Jr.

Theses and Dissertations

The routing and scheduling problem involves both constructing efficient routes to deliver goods or services to and from customers from a single depot or set of depots, as well as scheduling particular vehicles to these routes such that customers receive their goods within a specified time window. There have been several different methods developed to reduce the costs incurred in transporting goods or services (i.e. students) to customers (i.e. schools). This problem may be used to model many circumstances in logistics and public transportation. Several school districts do not utilize operations research techniques to minimize, as much as possible, the …

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Tunable Diode Laser Absorption Spectroscopy Verification Analysis For Use In The Combustion Optimization And Analysis Laser Laboratory, Christina R. Serianne Mar 2009

Tunable Diode Laser Absorption Spectroscopy Verification Analysis For Use In The Combustion Optimization And Analysis Laser Laboratory, Christina R. Serianne

Theses and Dissertations

The AFIT Combustion Optimization and Analysis Laser (COAL) laboratory has state-of-the-art laser diagnostic capability for combustion process. The research for this thesis served to enhance the COAL lab's capability. Currently, there are no known commercially available tunable diode lasers that produce Ultra-Violet radiation required for this analysis. Sum-frequency generation at 313.5 nm was utilized for high speed OH absorption and temperature measurements at a rate of 2kHz. The Tunable Diode Laser Absorption Spectroscopy system was validated by comparison with theoretical and well characterized experimental data by operating the system over a wide range of conditions for an H2 laminar flame …

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Rigidizable Inflatable Get-Away-Special Experiment (Rigex) Post Flight Analysis, Ground Testing, Modeling, And Future Applications, Brett J. Cooper Mar 2009

Rigidizable Inflatable Get-Away-Special Experiment (Rigex) Post Flight Analysis, Ground Testing, Modeling, And Future Applications, Brett J. Cooper

Theses and Dissertations

The Rigidizable Inflatable Get-Away-Special EXperiment (RIGEX) Space Shuttle experiment was run successfully onboard STS-123 (Endeavour) in March 2008. The objective of this thesis is to analyze the space flight and post space flight test data, correlate the data to previous ground tests, and update finite element models. In turn, this research will help demonstrate the feasibility of using lightweight and low stowage volume (high packaging ratio) inflatable/rigidizable space structures in remote sensing applications. RIGEX was an Air Force Institute of Technology graduate-student-built Space Shuttle cargo bay experiment intended to heat and inflate three 20-inch long carbon fiber tubes in a …

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Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez Mar 2009

Fatigue Evaluation Of Nanocomposites As Lightweight Electronic Enclosures For Satellites' Applications, Javier Rodriguez

Theses and Dissertations

Existing nanocomposite materials used for satellite applications don't offer the required conductivity and electromagnetic shielding protection, requiring metal shields in order to survive in space. The AFRL Materials and Manufacturing Directorate in conjunction with the private sector have developed a material that promises to blend the attributes of nanocomposites and metal materials. The M55J/RS3 material consists of carbon fibers combined with a polyisocyanate matrix, in which Nickel nanostrandsTM are added. The research effort investigated the changes in the EMI and ESD of the material after being subjected to cyclic loads. Four configurations of a symmetric layup with fibers oriented …

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Effects Of Contact Load On The Fretting Fatigue Behavior Of In-100 At Elevated Temperature, Alfred G. Traylor Ii Mar 2009

Effects Of Contact Load On The Fretting Fatigue Behavior Of In-100 At Elevated Temperature, Alfred G. Traylor Ii

Theses and Dissertations

This thesis studied the effects of contact load of 8006 N on the fretting fatigue behavior of IN-100 at an elevated temperature of 600°C. First, S-N curves were created for a range of applied axial stresses at an identical stress ratio of 0.03 at 8006 N. A condition of partial slip condition necessary to fretting fatigue was verified by generating hysteresis loops, plotting shear force against axial stress. The half-contact width and the crack initiation location were determined for all of the fretting specimens using optical and scanning electron microscopes. The contact widths were consistent with expected analytical values and …

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Surveillance Using Multiple Unmanned Aerial Vehicles, Christopher E. Booth Mar 2009

Surveillance Using Multiple Unmanned Aerial Vehicles, Christopher E. Booth

Theses and Dissertations

This study examines the performance and limitations of a heuristic cooperative control (CC) surveillance algorithm for multiple unmanned aerial vehicles (UAVs) under both simulation and demonstration. The algorithm generates Dubin's based paths and provides velocity feedback to accomplish simultaneous arrival onto a surveillance orbit around the target and maintains position while orbiting. The CC algorithm has two modes: one that generates commands to multiple UAVs for simultaneous arrival to a surveillance orbit, and one that maintains equal angular spacing about the orbit. In addition to positional performance metrics, percentage of target in-view time was also measured based on the UAV's …

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Effects Of Prior Aging At 316°C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 316°C: Experiment And Modeling, Ozgur Ozmen Mar 2009

Effects Of Prior Aging At 316°C In Argon On Inelastic Deformation Behavior Of Pmr-15 Polymer At 316°C: Experiment And Modeling, Ozgur Ozmen

Theses and Dissertations

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature polymer, was investigated at 316 deg C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain at zero stress and creep response are strongly affected by …

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Characterizing The Exhaust Plume Of The Three-Electrode Micro Pulsed Plasma Thrusters, Myeongkyo Seo Mar 2009

Characterizing The Exhaust Plume Of The Three-Electrode Micro Pulsed Plasma Thrusters, Myeongkyo Seo

Theses and Dissertations

Three-electrode micro-PPTs are a new version of two electrode micro-PPTs devices. Performance predictions and contamination expectations are essential characteristics needed by satellite designers. In order to focus on thruster specific impulse, thrust and efficiency, measuring the exhaust velocity or impulse bit and propellant consumption rate is essential. While this is not always possible to measure directly, focusing on the ejected mass from the PPT provides significant information allowing determination of these performance statistics. Specifically, focusing on exhaust angle distribution and velocity of the exhaust particles is the emphasis of this work. The results show that the three-electrode micro-PPT is more …

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Effects Of Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Composite With ±45º Fiber Orientation At 1200ºc, Muzaffer Ozer Mar 2009

Effects Of Environment On Creep Behavior Of Nextel720/Alumina-Mullite Ceramic Composite With ±45º Fiber Orientation At 1200ºc, Muzaffer Ozer

Theses and Dissertations

The present effort will investigate the off-axis creep behavior of the Nexte720/Alumina-Mullite CMC, a material system which relies on a porous alumina/mullite matrix for damage tolerance as compared to the pure alumina matrix in earlier studies. This research evaluated the creep behavior of N720/AM with a ± 45° fiber orientation at 1200°C in: laboratory air, steam, and argon environments. Creep-rupture tests at the creep stress levels of: 32, 30, 26, and 20 MPa were conducted in each environment. Additionally 35 MPa stress level examined in air and 13 MPa stress level examined both in air and steam. The N720/AM with …

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Hyperspectral Imaging Of A Turbine Engine Exhaust Plume To Determine Radiance, Temperature, And Concentration Spatial Distributions, Spencer J. Bowen Mar 2009

Hyperspectral Imaging Of A Turbine Engine Exhaust Plume To Determine Radiance, Temperature, And Concentration Spatial Distributions, Spencer J. Bowen

Theses and Dissertations

The usefulness of imaging Fourier transform spectroscopy (IFTS) when looking at a rapidly varying turbine engine exhaust scene was explored by characterizing the scene change artifacts (SCAs) present in the plume and the effect they have on the calibrated spectra using the Telops, Inc.-manufactured Field-portable Imaging Radiometric Spectrometer Technology, Midwave Extended (FIRST-MWE). It was determined that IFTS technology can be applied to the problem of a rapidly varying turbine engine exhaust plume due to the zero mean, stochastic nature of the SCAs, through the use of temporal averaging. The FIRST-MWE produced radiometrically calibrated hyperspectral datacubes, with calibration uncertainty of 35% …

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Predicting Solar Protons: A Statistical Approach, Jonathan C. Spaulding Mar 2009

Predicting Solar Protons: A Statistical Approach, Jonathan C. Spaulding

Theses and Dissertations

A small fraction of solar flares are accompanied by high energy (>10 MeV) protons. These events can cause degradation or failure of satellite systems and can be harmful to humans in space or in high altitude flight. For risk management purposes, the Air Force is interested in predicting these events. Several algorithms exist to do this operationally, but none predict when these events will occur with much accuracy. Here, we analyzed 3610 M1 and greater flares including 106 with proton events from the GOES sensors from 1 Jan 1986 to 31 Dec 2004 to produce new results, including a …

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Advanced Radiometry For High Discrimination Explosive Fireball Discrimination, Steven E. Slagle Mar 2009

Advanced Radiometry For High Discrimination Explosive Fireball Discrimination, Steven E. Slagle

Theses and Dissertations

The high explosive fireball phenomenological model for the mid wave infrared spectrum, developed by AFIT, performs classification from spectral signatures was modified to use radiometric intensities. Five bands were sequentially fit to derive the five physical fit parameters describing the fireball's temperature, size, soot absorption coefficient within 16% and emissions from the H2O and CO2 concentrations within 333% of the spectral model. This was improved by changing the model's band sizes, center, and fitting methods where all five fit parameters were matched to within 17% of spectral model. This demonstrated that a combination of radiometric intensities could …

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Investigation Of Electrical And Optical Properties Of Bulk Iii-V Ternary Semiconductors, Travis C. Gomez Mar 2009

Investigation Of Electrical And Optical Properties Of Bulk Iii-V Ternary Semiconductors, Travis C. Gomez

Theses and Dissertations

Bulk grown III-V ternary semiconductors of In0.08Ga0.92Sb and In0.15Ga0.85As were investigated through Hall-effect and photoluminescence measurements to determine carrier concentration, mobility, sheet resistivity, and luminescence spectrum. In the past, epitaxial layers of ternary compounds have been grown on binary compound substrates, and thus very limited lattice matched ternary alloys were available. Recently, bulk grown ternary substrates have been developed, and it has presented a renewed interest in using these substrates to grow high quality ternary compounds for use in many next generation optoelectronic devices. The results of photoluminescence (PL) study for the …

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Wave Optics Simulation Of Optically Augmented Retroreflections For Monostatic/Bistatic Detection, John J. Tatar Iii Mar 2009

Wave Optics Simulation Of Optically Augmented Retroreflections For Monostatic/Bistatic Detection, John J. Tatar Iii

Theses and Dissertations

Optical devices interrogated with a laser in the appropriate band can exhibit strong, deterministic reflections of the incident beam. This characteristic could be exploited for optical target detection and identification. The distribution of reflected power is strongly dependent on the geometry of the interrogation scenario, atmospheric conditions, and the cross section of the target optical device. Previous work on laser interrogation systems in this area has focused on analytic models or testing. To the best of my knowledge, I am presenting for the first time an approach to predict reflected power for a variety of interrogation configurations, targets, and propagation …

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Non-Destructive Evaluation Of Aerospace Composites, Jeremy D. Johnson Mar 2009

Non-Destructive Evaluation Of Aerospace Composites, Jeremy D. Johnson

Theses and Dissertations

Five methods of non-destructive material evaluation (NDE) were used to inspect various forms of damage commonly found in aerospace fiberglass composites: voids, edge and sub-surface delaminations, surface burning, and cracking. The images produced by X-ray, X-ray Computed Tomography, terahertz (THz) imaging, ultrasound, and flash IR thermography were analyzed for the detection of defects. Test results and analysis of each NDE method's capabilities provide a comparison study of conventional techniques versus the emerging technology of THz imaging for the non-destructive evaluation of aerospace composite materials. A comparison guide to the five methods' damage detection effectiveness for fiberglass composites is provided by …

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Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary Mar 2009

Electrostatic Discharge Properties Of Irradiated Nanocomposites, Joshua D. Mcgary

Theses and Dissertations

Modernization in space systems requires employment of new light-weight, high performance composite materials that reduce bulk weight and increase structural integrity. This thesis explored the behavior of one such material prior to and following a 35-year simulated space radiation life-cycle. Select electrical properties of nickel nanostrandTM-carbon composites in seven configurations were characterized prior to electron irradiation via surface and bulk resistivity measurements and contact electrostatic discharge (ESD) measurements. Following irradiation at a fluence of 1016 e-/cm2 at an average energy of 500 keV, measurements were repeated and compared against pre-irradiation data. Configuration D is …

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Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler Mar 2009

Patterning And Characterization Of Carbon Nanotubes Grown In A Microwave Plasma Enhanced Chemical Vapor Deposition Chamber, Mauricio Kossler

Theses and Dissertations

This research studies the growth of carbon nanotubes (CNT) from a nickel catalyst to be used on a field emission device. This thesis can be divided into three sections: the construction of a vacuum chamber for field emission testing, the design and fabrication of a triode structure to enable improved electron emission, and the pretreatment and growth of CNTs. To experimentally test the field emission of CNTs, a vacuum chamber must attain a vacuum of at least 10-5 torr. Our vacuum chamber designed and built achieved a maximum, final pressure of 10-8 torr. A triode structure was designed …

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