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Theses and Dissertations

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Full-Text Articles in Engineering

Attitude Control Of A Satellite Simulator Using Reaction Wheels And A Pid Controller, Ryan E. Snider Mar 2010

Attitude Control Of A Satellite Simulator Using Reaction Wheels And A Pid Controller, Ryan E. Snider

Theses and Dissertations

Attitude requirements of a satellite are determined by its mission: telecommunications, optical imagery, and meteorology to name a few. A satellite's ability to orient its mission critical hardware (solar arrays, attitude sensors, etc.), as well as its mission specific payload, is incumbent upon the performance of the satellite's attitude control system (ACS). For a highly accurate ACS and for moderately fast maneuverability, reaction wheels are preferred because they allow continuous and smooth control while inducing the smallest possible disturbance torques. The objective of this research is to design, build, test, and evaluate the performance of a reaction wheel ACS on-board …

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Design Analysis Of A Sapce Based Chromotomographic Hyperspectral Imaging Experiment, Todd A. Book Mar 2010

Design Analysis Of A Sapce Based Chromotomographic Hyperspectral Imaging Experiment, Todd A. Book

Theses and Dissertations

This research develops the design of several components and/or systems for an experimental space-based chromotomographic hyperspectral imager that is being built by the Air Force Institute of Technology. The design work includes three separate topics. The first topic was the development of a structure utilizing finite element analysis and eigenanalysis for the ground-based version of the chromotomographic experiment (CTEx). The ground-based experiment was performed as a risk mitigation measure for the space-based experiment. The second topic includes a design review of a contractor's proposed off-axis Mersenne telescope for the space-based chromotomographic hyperspectral imager. The work included the creation of preliminary …

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Relative Orbit Elements For Satellites In Elliptical Orbits, Kirk W. Johnson Mar 2010

Relative Orbit Elements For Satellites In Elliptical Orbits, Kirk W. Johnson

Theses and Dissertations

The purpose of this research was to describe the unperturbed relative motion of Earth satellites in elliptical orbits using a simple dynamics model whose parameters allow significant geometrical insight and operational efficacy. The goal was to retain the advantages of the Relative Orbit Elements (ROE) realization of the Hill-Clohessy-Wiltshire (HCW) equations, a linearized dynamics model for circular reference orbits. Specifically, this thesis analyzed the geometry of satellite rendezvous and proximity operations using the ROE parameters to characterize the model’s utility. Next, through a comprehensive literature review, this thesis sought possible approaches for developing a similarly useful parameterization for chief orbits …

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Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller Mar 2010

Mission Analysis And Design For Space Based Inter-Satellite Laser Power Beaming, Nicholas M. Keller

Theses and Dissertations

This research effort develops an interdisciplinary design tool to optimize an orbit for the purpose of wirelessly beaming power from the International Space Stations (ISS) Japanese Experimental Module Exposed Facility (JEM/EF) to a target satellite. For the purpose of this initiative, the target satellite will be referred to as FalconSAT6, a reference to the proposed follow-on satellite to the U.S. Air Force Academy’s (USAFA) FalconSAT5 program. The USAFA FalconSAT program provides cadets an opportunity to design, analyze, build, test and operate small satellites to conduct Department of Defense (DoD) space missions. The tool developed for this research is designed to …

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Estimating Characteristics Of A Maneuvering Reentry Vehicle Observed By Multiple Sensors, Evan M. Brooks Mar 2010

Estimating Characteristics Of A Maneuvering Reentry Vehicle Observed By Multiple Sensors, Evan M. Brooks

Theses and Dissertations

Post flight analysis of ballistic missile reentry vehicles is an area of focus for the U.S. Government, especially for those involved in ballistic missile defense. Typically, this analysis incorporates either a model-driven least squares filter or a data-following Kalman filter. The research performed here developed a filter that attempts to integrate the strengths of both filters. A least squares filter operates on observation data collected during exoatmospheric free flight and a Kalman filter is used to analyze data collected lower in the atmosphere, where potential maneuvers could be performed. Additionally, the filter was written to incorporate data from multiple sensors. …

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Investigation Of A Novel Compact Vibration Isolation System For Space Applications, Steven D. Miller Mar 2010

Investigation Of A Novel Compact Vibration Isolation System For Space Applications, Steven D. Miller

Theses and Dissertations

A novel compact vibration isolation system was designed, built, and tested for the Space Chromotomography Experiment (CTEx) being built by Air Force Institute of Technology (AFIT) researchers. CTEx is a multifunctional experimental imaging chromotomographic spectrometer designed for flight on the International Space Station (ISS) and is sensitive to jitter caused by vibrations both through the support structure as well as those produced on the optical platform by rotating optical components. CTEx demands a compact and lightweight means of vibration isolation and suppression from the ISS structure. Vibration tests conducted on an initial isolator design resulted in changes in the chosen …

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Prototype Development And Dynamic Characterization Of Deployable Cubesat Booms, Grant M. Thomas Mar 2010

Prototype Development And Dynamic Characterization Of Deployable Cubesat Booms, Grant M. Thomas

Theses and Dissertations

The current barrier to CubeSat proliferation is their lack of utility depth. These small satellites are exceptionally well suited for specific space missions such as space weather observation and other scientific data gathering exploits; however, they are not suited for every mission. The 10cm-cube form factor that gives the CubeSat its unique advantage is also its greatest hindrance. A potential bridge over this gap is the successful integration of deployable booms onto the CubeSat structure. With this research, the Air Force Institute of Technology (AFIT) explored the parameters of deployable tapespring booms using the triangular retractable and collapsible (TRAC) cross- …

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Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse Mar 2010

Preliminary Electrical Designs For Ctex And Afit Satellite Ground Station, Arthur L. Morse

Theses and Dissertations

This thesis outlines the design of the electrical components for the space-based ChromoTomography Experiment (CTEx). CTEx is the next step in the development of high-speed chromotomography at the Air Force Institute of Technology. The electrical design of the system is challenging due to the large amount of data that is acquired by the imager and the limited resources that is inherent with space-based systems. Additional complication to the design is the need to know the angle of a spinning prism that is in the field of view very precisely for each image. Without this precise measurement any scene that is …

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Accurate Dynamic Response Predictions Of Pnpsat I, Michael D. Trottier Mar 2010

Accurate Dynamic Response Predictions Of Pnpsat I, Michael D. Trottier

Theses and Dissertations

Researchers at the Air Force Institute of Technology (AFIT) and the Operationally Responsive Space (ORS) Office have conducted extensive vibration testing and structural modeling on the first ORS Plug-and-Play Satellite (PnPSAT I). The intent of this research effort is to evaluate the premise that current post-integration spacecraft environmental test requirements can be reduced or modified using accurately tuned finite element (FE) models. As part of this research, modal testing was conducted on the PnPSAT I structural panels at AFIT. The modal testing was part of a much larger series of experimental trials on various configurations of PnPSAT I at the …

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Minimizing Losses In A Space Laser Power Beaming System, Charlie T. Bellows Mar 2010

Minimizing Losses In A Space Laser Power Beaming System, Charlie T. Bellows

Theses and Dissertations

A mathematical model is developed to track the amount of power delivered in a wireless laser power beaming system. In a wireless system the power proceeds through several different stages before being delivered to a payload for use. Each of these stages results in power losses that are thoroughly examined and modeled, allowing for the calculation of the likely amount of power delivered. Adjusting variable factors within the model allows for the optimization of the system for a specific task. The model shows that an optimized wireless power transfer system can deliver enough power to meet the space experiment objectives. …

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Development Of A Remotely Operated Autonomous Satellite Tracking System, Michael E. Graff Mar 2010

Development Of A Remotely Operated Autonomous Satellite Tracking System, Michael E. Graff

Theses and Dissertations

AFIT is currently developing a capability to remotely and autonomously track LEO satellites using commercial telescopes. Currently, the system is capable of open-loop tracking based on Two-Line Element sets (TLEs) downloaded from NORAD’s space object catalog. The ability to actively track using a closed-loop control system would allow tracking of satellites which deviated from the published TLEs along with providing some information about the object’s new orbital elements. To accomplish closed-loop tracking, the object is imaged by a digital camera connected to a wide field-of-view (WFOV) spotting scope. Software was developed to provide azimuth and elevation inputs in order to …

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Mission Analysis For Multiple Rendezvous Of Near-Earth Asteroids Using Earth Gravity Assist, Uriah J. Tobey Mar 2010

Mission Analysis For Multiple Rendezvous Of Near-Earth Asteroids Using Earth Gravity Assist, Uriah J. Tobey

Theses and Dissertations

The Jet Propulsion Laboratory (JPL) catalog of near-Earth objects (NEOs) such as asteroids and comets contains over 6600 asteroids and 150 comets as of February of 2010. This includes over 1000 potentially hazardous asteroids, or objects with orbits that pass close enough to Earth to pose a potential impact threat. The asteroid community believes there are a significant number of objects still undiscovered, which makes finding, tracking, and calculating missions to study these objects an active area of research. This study was based on finding orbit solutions using Earth gravity assist to visit one near-Earth object (NEO) a year for …

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A Simulation Based Methodology To Examine The B-1b'S An/Alq-161 Maintenance Process, Ricardo R. Garza Mar 2010

A Simulation Based Methodology To Examine The B-1b'S An/Alq-161 Maintenance Process, Ricardo R. Garza

Theses and Dissertations

The B-1 Bomber is the Air Force’s only supersonic, conventional-only strike platform. This thesis looks at the maintenance procedures associated with the defensive electronic counter measure (ECM) system on the B-1B, designated the AN/ALQ-161. Computer simulation of the current line-replaceable-unit maintenance network for Ellsworth AFB and Dyess AFB is modeled. In addition, two hypothetical repair networks are proposed and analyzed. This research considers the applicability of this type of computer simulation, using ARENA software to study the AN/ALQ-161 repair system. The contribution of this research is a discrete simulation methodology specific to the AN/ALQ-161 LRU repair line. Two response variables …

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Simulation Analysis Of High Velocity Maintenance For The B-1b, Anson R. Park Mar 2010

Simulation Analysis Of High Velocity Maintenance For The B-1b, Anson R. Park

Theses and Dissertations

This thesis explores the impact that High Velocity Maintenance (HVM) will have on aircraft availability rates for the B-1B by examining the proposed changes to the field maintenance and supply processes for the two B-1B squadrons of the 28th Bombardment Wing located at Ellsworth AFB, SD. There is a significant restructuring of depot level maintenance planned with the implementation of HVM, and the impact that this will have on base-level operations is important to determine, for it will provide insight as to whether or not HVM will be a feasible program with a high probability of successfully improving B-1B aircraft …

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Development Of Measures To Assess Product Modularity And Reconfigurability, Amie C. Stryker Mar 2010

Development Of Measures To Assess Product Modularity And Reconfigurability, Amie C. Stryker

Theses and Dissertations

Several fundamental benefits of modularity are agreed upon by industry including reusability, flexibility, reconfigurability and extensibility. Interfaces within or between modules which establish provide/depend relationships are the focus of current modularity measures. This research outlines a new method and measures for assessing product modularity in terms of degree of coupling and the recognized modularity benefits. A five–step analysis process is developed and used to guide the modularity assessment. Defining and decomposing products are performed first. Using the resultant functional model from the first step, the identified functions are mapped to modules in a product in the second step. In the …

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Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy, Douglas E. Thornton Mar 2010

Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy, Douglas E. Thornton

Theses and Dissertations

To better understand the laser kinetics of an alkali gain medium, hard collisions, or velocity-changing collisions, has been studied and a velocity-changing collisional rate has been calculated. Previous works have studied these collisions, but no rate has been calculated. Using the precise tool of sub-Doppler spectroscopy, atomic hard collisions can be observed. The collected spectra are fitted with two different line shapes to demonstrate the accuracy of this method. From the fits, the number of hard collisions can be extracted. The time scale of the hard collisions in rubidium is interpolated by varying the chopping frequency of the pump beam, …

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Cca: Exploratory Case Study Of Construction In A Contingency Environment, Michael J. Pluger Mar 2010

Cca: Exploratory Case Study Of Construction In A Contingency Environment, Michael J. Pluger

Theses and Dissertations

Top military leadership has identified problems with the timeliness and effectiveness of DoD contingency construction support. Qualitative data was collected in order to gain clarity on the problem space and lay a foundation for solution generation and selection. Interviews were conducted with agents with experience within the Iraq and Afghanistan theater of operation as well as support functions for the Pentagon. Commanders, Engineers, Lawyers, Acquisition Attorneys, Staff Officers and Program Managers have been interviewed. The interviews have been analyzed using open coding to answer research question and identify to emergent themes and concepts. The data collected has revealed that Contingency …

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Knowledge Transformation In The United States Air Force Civil Engineer Career Field: A System Dynamics Approach, Gregory J. Ward Mar 2010

Knowledge Transformation In The United States Air Force Civil Engineer Career Field: A System Dynamics Approach, Gregory J. Ward

Theses and Dissertations

Recent operations in Iraq and Afghanistan have brought the level of expeditionary contractors to historically unprecedented levels, altering the work composition for military engineers. The alteration has shifted emphasis from technical knowledge areas toward managerial knowledge associated with supervising the increased number of contractors. This research utilizes System Dynamics modeling to analyze this shift in the United States Air Force Civil Engineer officer career field and resulting transformative effect on career field knowledge levels, both technical and managerial. The model is then tested with multiple external policy adjustments in the areas of career field structure, training, and operating policy. Results …

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Part Count: Monolithic Part Effects On Manufacturing Labor Cost, An Aircraft Applied Model, Aaron M. Lemke Mar 2010

Part Count: Monolithic Part Effects On Manufacturing Labor Cost, An Aircraft Applied Model, Aaron M. Lemke

Theses and Dissertations

There are significantly different manufacturing processes and part counts associated with composites that are not currently addressed within the aircraft procurement and life cycle management processes in the Department of Defense (DoD). A series of affordability initiatives have culminated in significant evidence over the last decade to better quantify the impact of primarily composite structures in aircraft. An Air Force Research Laboratory program, Advanced Composite Cargo Aircraft (ACCA), provides substantial support for the impact of part size on life cycle cost for payload aircraft. This research evaluates select methods used and seeks to introduce modifications to the projected manufacturing hours …

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Development Of Morphing Aircraft Structure Using Smp, Soo-Chan Jee Mar 2010

Development Of Morphing Aircraft Structure Using Smp, Soo-Chan Jee

Theses and Dissertations

The U.S Air Force needs new aircraft which provide longer flight time, less fuel consumption, better aerodynamics in order to perform Air Force missions successfully as the mission environment changes rapidly. A morphing wing aircraft is considered as a potential new aircraft for those missions. This thesis explores Shape Memory Polymer (SMP) properties test results and its application for morphing wing skin. Several SMP composite laminates were considered for investigating shape changing characteristics required for morphing skin. The braided composite preforms used in making SMP composites were explored in morphing wing operating system based on the results of property tests. …

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Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris Mar 2010

Optical Properties Of Si, Ge, Gaas, Gasb, Inas, And Inp At Elevated Temperatures, Thomas R. Harris

Theses and Dissertations

Investigation of the optical and electrical behavior of some semiconductors at very high temperatures has not been an area of much study, at least not experimentally. The importance of such research becomes obvious due to the effects of high temperatures on semiconductor devices such as infrared detectors and light emitters. Besides the destructive effects of thermal stress and melting, changes in the optical properties of the material can greatly affect device performance. In this research, the infrared absorption of Si, Ge, GaAs, GaSb, InAs, and InP was measured from 0.6 to 25 μm at temperatures ranging from 295 up to …

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Application Of Satellite-Derived Wind Profiles To Joint Precision Airdrop System (Jpads) Operations, David C. Meier Mar 2010

Application Of Satellite-Derived Wind Profiles To Joint Precision Airdrop System (Jpads) Operations, David C. Meier

Theses and Dissertations

The Joint Precision Airdrop System has revolutionized military airdrop capability, allowing accurate delivery of equipment and supplies to smaller drop zones, from higher altitudes than was previously possible. This capability depends on accurate wind data which is currently provided by a combination of high-resolution forecast models and GPS dropsondes released in the vicinity of the dropzone shortly before the airdrop. This research develops a windprofiling algorithm to derive the needed wind data from passive IR satellite soundings, eliminating the requirement for a hazardous dropsonde pass near the drop zone, or allowing the dropsonde to be dropped farther from the dropzone. …

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Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller Mar 2010

Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller

Theses and Dissertations

Laser induced fluorescence was used to study how pump pulse duration and alkali recycle time effects maximum power output in a Diode Pumped Alkali Laser (DPAL) system. A high intensity short pulsed pump source was used to excited rubidium atoms inside a DPAL-type laser. The maximum output power of the laser showed a strong dependence upon the temporal width of the pump pulse in addition to the input pump intensity. A linear relationship was observed between the maximum output power and the pulse width due to the effective lifetime of the excited state, defined as the time it takes for …

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Development And Demonstration Of A Field-Deployable Fast Chromotomographic Imager, Daniel C. O'Dell Mar 2010

Development And Demonstration Of A Field-Deployable Fast Chromotomographic Imager, Daniel C. O'Dell

Theses and Dissertations

A field deployable hyperspectral imager utilizing chromotomography (CT), with a direct vision prism (DVP) as the dispersive element, has been constructed at AFIT. This research is focused on the development and demonstration of the CT imager. An overview of hyperspectral imaging, chromotomography, a synopsis of reconstruction algorithms, and other CT instruments are given. The importance of component alignment, instrument calibration, and exact prism angular position data are discussed. A simplistic \shift and add" reconstruction algorithm was utilized for this research. Although limited in its ability to reconstruct a spatially and spectrally diverse scene, the algorithm was adequate for the testing …

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Gadolinium Oxide/Silicon Thin Film Heterojunction Solid-State Neutron Detector, Christopher M. Young Mar 2010

Gadolinium Oxide/Silicon Thin Film Heterojunction Solid-State Neutron Detector, Christopher M. Young

Theses and Dissertations

The internal conversion electron emission from the de-excitation of the Gd-158m nucleus was explored as a means for neutron detection. Thin film gadolinium oxide (Gd2O3) and p-type silicon heterojunction diodes were produced using a supercritical water deposition process. Pulse height spectroscopy was conducted on the novel diodes while they were subjected to a moderated plutonium-beryllium (PuBe) source flux of 104 thermal neutrons/cm2 s. Coincident gamma spectroscopy was employed to verify the 1107.6 keV photon emissions from the diode indicative of successful neutron capture by Gd-157 and the subsequent de-excitation of the Gd-158m nucleus. Neutron …

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Synchronization Voter Insertion Algorithms For Fpga Designs Using Triple Modular Redundancy, Jonathan Mark Johnson Mar 2010

Synchronization Voter Insertion Algorithms For Fpga Designs Using Triple Modular Redundancy, Jonathan Mark Johnson

Theses and Dissertations

Triple Modular Redundancy (TMR) is a common reliability technique for mitigating single event upsets (SEUs) in FPGA designs operating in radiation environments. For FPGA systems that employ configuration scrubbing, majority voters are needed in all feedback paths to ensure proper synchronization between the TMR replicates. Synchronization voters, however, consume additional resources and impact system timing. This work introduces and contrasts seven algorithms for inserting synchronization voters while automatically performing TMR. The area cost and timing impact of each algorithm on a number of circuit benchmarks is reported. The work demonstrates that one of the algorithms provides the best overall timing …

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Particle Image Velocimetry Analysis On The Effects Of Stator Loading On Transonic Blade-Row Interactions, Scott B. Reynolds Mar 2010

Particle Image Velocimetry Analysis On The Effects Of Stator Loading On Transonic Blade-Row Interactions, Scott B. Reynolds

Theses and Dissertations

Experiments have been performed using the Air Force Research Laboratory (AFRL) Blade-Row Interaction (BRI) rig to investigate interactions between a loaded stator and transonic rotor. The BRI rig is a high-speed, highly loaded compressor consisting of a swirler/deswirler, a transonic rotor and a stator. The swirler/deswirler of the BRI rig is used to simulate an embedded transonic fan stage with realistic geometry which produces a wake through diffusion. Details of the unsteady flow field between the stator and rotor were obtained using Particle Image Velocimetry (PIV). Flow visualization images and PIV data that facilitate analysis of vortex shedding, wake motion, …

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Flexible Computing Architecture For Real Time Skin Detection, Matthew P. Hornung Mar 2010

Flexible Computing Architecture For Real Time Skin Detection, Matthew P. Hornung

Theses and Dissertations

In both the Air Force and Search and Rescue Communities, there is a current need to detect and characterize persons. Existing methods use red-green-blue (RGB) imagery, but produce high false alarm rates. New technology in multi-spectral skin detection is better than the existing RGB methods, but lacks a control and processing architecture to make them efficient for real time problems. We hypothesize that taking a minimalistic approach to the software design, we can perform image preprocessing, feature computation, and skin detection in real time. A number of applications require accurate detection and characterization of persons, human measurement and signature intelligence …

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Multi-Objective Constraint Satisfaction For Mobile Robot Area Defense, Kenneth W. Mayo Mar 2010

Multi-Objective Constraint Satisfaction For Mobile Robot Area Defense, Kenneth W. Mayo

Theses and Dissertations

In developing multi-robot cooperative systems, there are often competing objectives that need to be met. For example in automating area defense systems, multiple robots must work together to explore the entire area, and maintain consistent communications to alert the other agents and ensure trust in the system. This research presents an algorithm that tasks robots to meet the two specific goals of exploration and communication maintenance in an uncoordinated environment reducing the need for a user to pre-balance the objectives. This multi-objective problem is defined as a constraint satisfaction problem solved using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). Both …

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Analysis Of A Rumor Routing Protocol With Limited Packet Lifetimes, Peter R. Francik Mar 2010

Analysis Of A Rumor Routing Protocol With Limited Packet Lifetimes, Peter R. Francik

Theses and Dissertations

Wireless sensor networks require specialized protocols that conserve power and minimize network traffic. Therefore, it is vitally important to analyze how the parameters of a protocol affect these metrics. In doing so, a more efficient protocol can be developed. This research evaluates how the number of nodes in a network, time between generated agents, lifetime of agents, number of agent transmissions, time between generated queries, lifetime of queries, and node transmission time affect a modified rumor routing protocol for a large-scale, wireless sensor network. Furthermore, it analyzes how the probability distribution of certain protocol parameters affects the network performance. The …

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