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Articles 3031 - 3060 of 5700
Full-Text Articles in Engineering
Integration Of Information Operations Theory Into The Corporate Air Force, Thomas R. Kettles Jr.
Integration Of Information Operations Theory Into The Corporate Air Force, Thomas R. Kettles Jr.
Theses and Dissertations
The purpose of this research was to determine the desired end-state for company grade officers in terms of an information operations education. Specifically, an examination of company grade officer curricula from the pre-commissioning sources to the Squadron Officer College was performed. This assessment was then compared to the Air Force Institute of Technology Cyber Competency Areas Framework. Any areas that were missing from the current company grade officer curricula were identified and a proposed implementation plan was presented to correct these deficiencies. To aid in developing an implementation plan, redundancies between the two Squadron Officer College courses were identified. Furthermore, …
Design And Optimization Of Broadband High Impedance Ground Planes (Higp) For Surface Mount Antennas, Murat Dogrul
Design And Optimization Of Broadband High Impedance Ground Planes (Higp) For Surface Mount Antennas, Murat Dogrul
Theses and Dissertations
Gain and bandwidth metrics of broad-band low-profile antennas severely deteriorate when they are placed conformally onto the conductive skins of air, sea, and ground platforms. This detrimental effect is primarily due to out-of-phase reflections from the conductive body interfering with the antenna’s self radiation. Furthermore, lateral waves launched by the antenna couple into the thin substrate placed between the antenna and the platform, giving rise to surface waves resulting in significant diffraction from the edges of the substrate. To remedy these two major mechanisms degrading antenna performance, high impedance ground planes (HIGP) were designed. HIGPs made of a 2-dimensional periodic …
Developing An Excel Decision Support System Using In-Transit Visibility To Decrease Dod Transportation Delays, Brian B. Stone
Developing An Excel Decision Support System Using In-Transit Visibility To Decrease Dod Transportation Delays, Brian B. Stone
Theses and Dissertations
The United States Air Force's Air Mobility Command (AMC) is responsible for efficiently transporting military personnel and cargo throughout the world. Organizations throughout the transportation system search for ways to decrease cargo transportation time as part of their ongoing mission to provide timely airlift services to the DoD. As cargo is transported through the transportation system it is in one of two states; waiting at an air base for transportation or in some phase of the loading, transportation, or unloading process. The loading and unloading process has been streamlined throughout the transportation system to a point which leaves little room …
Impacts Of Weather Variations On Energy Consumption Efforts At U.S. Air Force Installations, James S. Griffin
Impacts Of Weather Variations On Energy Consumption Efforts At U.S. Air Force Installations, James S. Griffin
Theses and Dissertations
Energy consumption is a national concern, as evidenced by federal laws aimed toward facility energy conservation measures for federal organizations. Factors, primarily weather variables, that significantly impact energy consumption must be addressed and understood to align resources and programs to meet federal energy reduction goals. An energy model was created and tested to produce an appropriate forecasting tool for energy consumption. Energy demand at Air Force installations primarily depends on climatic conditions, with a small portion attributed to a base level of non-climatic conditions, such as interior lighting and appliance loads. By gathering all energy consumption and meteorological data covering …
Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican
Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican
Theses and Dissertations
The current research is focused on the design and fabrication of an electrically programmable diffraction grating using standard micro electro mechanical systems (MEMS) technology. The goal is to design a beam steering element required to build very small hyperspectral imaging (HSI) sensors. The diffraction grating will be used to perform beam-dispersion - a critical step in the imaging process. The proposed transmissive diffraction grating based approach will minimize the overall size and the number of components in the physical design of the hyperspectral imagers, thereby enabling us to exploit the traditional advantages of MEMS such as increased reliability, smaller size, …
Multi-Class Classification Fusion Using Boosting For Identifying Steganography Methods, Benjamin M. Rodriguez, Gilbert L. Peterson
Multi-Class Classification Fusion Using Boosting For Identifying Steganography Methods, Benjamin M. Rodriguez, Gilbert L. Peterson
Faculty Publications
No abstract provided.
Joint Image And Pupil Plane Reconstruction Algorithm Based On Bayesian Techniques, James D. Phillips
Joint Image And Pupil Plane Reconstruction Algorithm Based On Bayesian Techniques, James D. Phillips
Theses and Dissertations
The focus of this research was to develop an joint pupil and focal plane image recovery algorithm for use with coherent LADAR systems. The benefits of such a system would include increased resolution with little or no increase in system weight and volume as well as allowing for operation in the absence of natural light since the target of interest would be actively illuminated. Since a pupil plane collection aperture can be conformal, such a system would also potentially allow for the formation of large synthetic apertures. The system is demonstrated to be robust and in all but extreme cases …
A Systematic Approach For Securing Our Space Assets, Heather Yates, Michael R. Grimaila
A Systematic Approach For Securing Our Space Assets, Heather Yates, Michael R. Grimaila
Faculty Publications
We are surrounded by the use of space assets, but for the most part are unaware of their impact on our lives. On a daily basis, space assets contribute to our well-being and others around the world. Space activities have enhanced security, monitored the environment, improved and increased information growth and flow, created economic growth, and changed the way people around the world live and work.[1] Since the 1991 Gulf War, we have also come to understand how much the US military depends on space. Military forces use satellite information for communications, intelligence, surveillance, reconnaissance, warning, weather, navigation, and timing. …
Graduate School Academic Catalog 2008-2009, Graduate School Of Engineering And Management, Air Force Institute Of Technology
Graduate School Academic Catalog 2008-2009, Graduate School Of Engineering And Management, Air Force Institute Of Technology
AFIT Documents
The Graduate Catalog represents the offerings, programs, and requirements in effect at the time of publication.
Network Formation Using Ant Colony Optimization -- A Systematic Review, Steven C. Oimoen, Gilbert L. Peterson, Kenneth M. Hopkinson
Network Formation Using Ant Colony Optimization -- A Systematic Review, Steven C. Oimoen, Gilbert L. Peterson, Kenneth M. Hopkinson
Faculty Publications
A significant area of research in the field of hybrid communications is the Network Design Problem (NDP) [1]. The NDP is an NP complete problem [1] that focuses on identifying the optimal network topology for transmitting commodities between nodes, under constraints such as bandwidth, limited compatible directed channels, and link and commodity costs. The NDP focuses on designing a flexible network while trying to achieve optimal flow or routing. If a link (or arc) is used, then an associated fixed cost of the edge is incurred. In addition, there is a cost for using the arc depending on the flow. …
Performance Comparison Of Pb(Zr0.52Ti0.48)O3-Only And Pb(Zr0.52Ti0.48)O3-On-Silicon Resonators, Hengky Chandrahalim, Sunil A. Bhave, Ronald G. Polcawich, Jeff Pulskamp, Dan Judy, Roger Kaul, Madan Dubey
Performance Comparison Of Pb(Zr0.52Ti0.48)O3-Only And Pb(Zr0.52Ti0.48)O3-On-Silicon Resonators, Hengky Chandrahalim, Sunil A. Bhave, Ronald G. Polcawich, Jeff Pulskamp, Dan Judy, Roger Kaul, Madan Dubey
Faculty Publications
This paper provides a quantitative comparison and explores the design space of lead zirconium titanate (PZT)–only and PZT-on-silicon length-extensional mode resonators for incorporation into radio frequency microelectromechanical system filters and oscillators. We experimentally measured the correlation of motional impedance (RX) and quality factor (Q) with the resonators’ silicon layer thickness (tSi). For identical lateral dimensions and PZT-layer thicknesses (tPZT), the PZT-on-silicon resonator has higher resonant frequency (fC), higher Q (5100 versus 140), lower RX (51 Ω versus 205 Ω), and better linearity [third-order input intercept …
Forensics Image Background Matching Using Scale Invariant Feature (Sift)Transform And Speeded Up Robust Features (Surf), Paul N. Fogg Ii
Forensics Image Background Matching Using Scale Invariant Feature (Sift)Transform And Speeded Up Robust Features (Surf), Paul N. Fogg Ii
Theses and Dissertations
In criminal investigations, it is not uncommon for investigators to obtain a photograph or image that shows a crime being committed. Additionally, thousands of pictures may exist of a location, taken from the same or varying viewpoints. Some of these images may even include a criminal suspect or witness. One mechanism to identify criminals and witnesses is to group the images found on computers, cell phones, cameras, and other electronic devices into sets representing the same location. One or more images in the group may then prove the suspect was at the crime scene before, during, and/or after a crime. …
Electrical Activation Studies Of Silicon Implanted Aluminum Gallium Nitride With High Aluminum Mole Fraction, Elizabeth A. Moore
Electrical Activation Studies Of Silicon Implanted Aluminum Gallium Nitride With High Aluminum Mole Fraction, Elizabeth A. Moore
Theses and Dissertations
This research demonstrates a method for producing highly conductive Si-implanted n-type aluminum gallium nitride (AlxGa1-xN) alloys, and represents a comprehensive analysis of the resulting material's electrical and optical properties as a function of Al mole fraction, anneal temperature, anneal time, and implantation dose. Highly conductive alloys are critical to the fabrication of devices operating in deep UV, high-temperature, high-power, and high-frequency environments, and thus this research is significant in regard to the application of such devices. The AlxGa1-xN wafers of this study, with Al concentrations of 10 to 50%, were implanted at …
Piezo-Electrochemical Transducer Effect (Pect) Intercalated Graphite Micro-Electromechanical Actuators, Glen A. Kading
Piezo-Electrochemical Transducer Effect (Pect) Intercalated Graphite Micro-Electromechanical Actuators, Glen A. Kading
Theses and Dissertations
The purpose of this research is to investigate the Piezo-Electrochemical Transducer (PECT) effect in intercalated graphite as a possible mechanism of actuation for micro-electromechanical systems (MEMS). This dissertation presents the results of research into the PECT effect in H2SO4-intercalated graphitized carbon fibers, including both electrical and mechanical characteristics of this effect. PECT fibers achieve up to 1.7% strain at 1.4 V of applied potential. In contrast, the piezoelectric material polyvinylidene difluoride (PVDF) generates only 0.01% strain and polysilicon thermal expansion between 0.02 and 0.06% strain depending on the thermal conductivity of the particular polysilicon that the actuators are fabricated in. …
A Nondestructive Technique For Determining Complex Permittivity And Permeability Of Magnetic Sheet Materials Using Two Flanged Rectangular Waveguides, Milo W. Hyde Iv, Michael J. Havrilla
A Nondestructive Technique For Determining Complex Permittivity And Permeability Of Magnetic Sheet Materials Using Two Flanged Rectangular Waveguides, Milo W. Hyde Iv, Michael J. Havrilla
Faculty Publications
In this paper, a nondestructive technique for determining the complex permittivity and permeability of magnetic sheet materials using two flanged rectangular waveguides is presented. The technique extends existing single probe methods by its ability to simultaneously measure reflection and transmission coefficients imperative for extracting both permittivity and permeability over all frequencies. Using Love’s Equivalence Principle, a system of coupled magnetic field integral equations (MFIEs) is formed. Evaluation of one of the two resulting spectral domain integrals via complex plane integration is discussed. The system, solved via the Method of Moments (MoM),yields theoretical values for the reflection and transmission coefficients. These …
Time Dependent Discrete Ordinates Neutron Transport Using Distribution Iteration In Xyz Geometry, James R. Dishaw
Time Dependent Discrete Ordinates Neutron Transport Using Distribution Iteration In Xyz Geometry, James R. Dishaw
Theses and Dissertations
The DI algorithm is an alternative to source iteration that, in our testing, does not require an accelerator. I developed a formal verification plan and executed it to verify the results produced by my code that implemented DI with the above features. A new, matrix albedo, boundary condition treatment was developed and implemented so that infinite-medium benchmarks could be included in the verification test suite. The DI algorithm was modified for parallel efficiency and the prior instability of the refinement sweep was corrected. The testing revealed that DI performed as well or faster than source iteration with DSA and that …
Global Positioning System Systems Engineering Case Study, Air Force Center For Systems Engineering, Patrick J. O'Brien, John M. Griffin
Global Positioning System Systems Engineering Case Study, Air Force Center For Systems Engineering, Patrick J. O'Brien, John M. Griffin
AFIT Documents
No abstract provided.
An Experimental Technique For The Evaluation Of Strain Dependent Material Properties Of Hard Coatings, Shad A. Reed, Anthony N. Palazotto, William P. Baker
An Experimental Technique For The Evaluation Of Strain Dependent Material Properties Of Hard Coatings, Shad A. Reed, Anthony N. Palazotto, William P. Baker
Faculty Publications
A novel vibration experiment consisting of a free-free boundary condition, an electromagnetic excitation source, a vacuum chamber, and a laser vibrometer based surface measurement system has been developed that permits high levels of excitation on highly damped specimens with a minimal amount of unwanted systematic error. While some of the aspects of this experiment are not unique, when combined with a processing technique that accounts for the nonlinearities present in the system, this experiment permits, accurate measurement of strain dependent stiffness and damping properties of hard coatings at high strain levels. This procedure has been demonstrated using a titanium beam …
Search Techniques For Multi-Objective Optimization Of Mixed Variable Systems Having Stochastic Responses, Jennifer G. Walston
Search Techniques For Multi-Objective Optimization Of Mixed Variable Systems Having Stochastic Responses, Jennifer G. Walston
Theses and Dissertations
A research approach is presented for solving stochastic, multi-objective optimization problems. First, the class of mesh adaptive direct search (MADS) algorithms for nonlinearly constrained optimization is extended to mixed variable problems. The resulting algorithm, MV-MADS, is then extended to stochastic problems (MVMADS-RS), via a ranking and selection procedure. Finally, a two-stage method is developed that combines the generalized pattern search/ranking and selection (MGPS-RS) algorithms for single-objective, mixed variable, stochastic problems with a multi-objective approach that makes use of interactive techniques for the specification of aspiration and reservation levels, scalarization functions, and multi-objective ranking and selection. A convergence analysis for the …
Hybrid Micro-Electro-Mechanical Tunable Filter, Edward M. Ochoa
Hybrid Micro-Electro-Mechanical Tunable Filter, Edward M. Ochoa
Theses and Dissertations
While advantages such as good thermal stability and processing-chemical compatibilities exist for common monolithic-integrated micro-electro-mechanically tunable filters (MEM-TF) and MEM-tunable vertical cavity surface emitting lasers (MT-VCSEL), they often require full processing to determine device characteristics. Alternatively, the MEM actuators and the optical parts may be fabricated separately, then subsequently bonded. This "hybrid approach" potentially increases design flexibility. Since hybrid techniques allow integration of heterogeneous material systems, "best of breed" compound optoelectronic devices may be customized to enable materials groups to be optimized for tasks they are best suited. Thus, as a first step toward a hybrid (AlxGa1- …
Final Assembly, Testing And Processing Of The Rigidizable Inflatable Get-Away-Special Experiment (Rigex) For Spaceflight Qualification, Jeremy J. Owens
Final Assembly, Testing And Processing Of The Rigidizable Inflatable Get-Away-Special Experiment (Rigex) For Spaceflight Qualification, Jeremy J. Owens
Theses and Dissertations
The purpose of this research is to complete the building, testing, verification, and qualification of the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX) for spaceflight. The process of qualifying a payload for spaceflight is discussed, specifically addressing the issues of operability and survivability verification of a general payload. The spaceflight qualification process is then applied to the RIGEX payload at the Air Force Institute of Technology (AFIT) and at the Johnson Spaceflight Center (JSC) in Houston, TX, capstoning the work of 12 masters students and 3 summer interns that has already gone into the RIGEX project over the last 7 years. The …
Optimal Control Strategies For Constrained Relative Orbits, David J. Irvin Jr.
Optimal Control Strategies For Constrained Relative Orbits, David J. Irvin Jr.
Theses and Dissertations
The US Air Force's ability to protect space assets is enhanced by a proficiency in satellite proximity operations and Space Situational Awareness (SSA). In pursuit of that proficiency, this research develops a key capability of interest to mission planners; the ability of a deputy satellite to "hover" within a defined volume fixed in the vicinity of a chief satellite for an extended period of time. This research finds optimal trajectories, produced with discrete-thrusts, that minimize fuel spent per unit time and stay within the user-defined volume, thus providing a practical hover capability in the vicinity of the chief. The work …
Radar System Characterization Extended To Hardware In The Loop Simulation For The Lab-Volt™ Training System, Oscar C. Mayhew
Radar System Characterization Extended To Hardware In The Loop Simulation For The Lab-Volt™ Training System, Oscar C. Mayhew
Theses and Dissertations
Modeling RADAR signals in software allows the testing of potential electronic counter measures and electronic counter counter measures without the associated RADAR hardware and test facilities. Performing a characterization process on a real world RADAR system reveals all imperfections within the system. The Lab-Volt™ RADAR system served as the characterized real world RADAR system. The characterization process consisted of measurements at selected front panel locations on the Lab-Volt™ transmitter module, antenna pedestal, receiver module, and dual channel sampler module. Due to the overwhelming influence of antenna parameters on a received signal, the characterization process also attempted to derive an antenna …
Raman Scattering Study Of Supercritical Bi-Component Mixtures Injected Into A Subcritical Environment, Young Man An
Raman Scattering Study Of Supercritical Bi-Component Mixtures Injected Into A Subcritical Environment, Young Man An
Theses and Dissertations
This research studies the species distribution profiles of methane/ethylene bi-components at downstream locations filled with subcritical nitrogen in a closed chamber. Unique thermodynamic and transport properties of supercritical fluids along with phase transition phenomena during fuel injection process can significantly change combustion characteristics inside a scramjet combustor. Plume properties of supercritical jets are of great interests to the studies of fuel/air mixing and subsequent combustion. The primary goal of this research is to help to clarify whether there is any preferential condensation within the condensed jets. The Raman Scattering technique is used to quantify spatial distribution of injected methane and …
The Effects Of Signal And Image Compression Of Sar Data On Change Detection Algorithms, Kiran Shenoy
The Effects Of Signal And Image Compression Of Sar Data On Change Detection Algorithms, Kiran Shenoy
Theses and Dissertations
With massive amounts of SAR imagery and data being collected, the need for effective compression techniques is growing. One of the most popular applications for remote sensing is change detection, which compares two geo-registered images for changes in the scene. While lossless compression is needed for signal compression, the same is not often required for image compression. In almost every case the compression ratios are much higher in lossy compression making them more appealing when bandwidth and storage becomes an issue. This research analyzes different types of compression techniques that are adapted for SAR imagery, and tests these techniques with …
Bipolar Cascade Vertical Cavity Surface Emitting Lasers For Rf Photonic Link Applications, William J. Siskaninetz
Bipolar Cascade Vertical Cavity Surface Emitting Lasers For Rf Photonic Link Applications, William J. Siskaninetz
Theses and Dissertations
The development and demonstration of bipolar cascade vertical cavity surface emitting lasers is presented. The systematic approach to designing, fabricating, and characterizing the critical tunnel junction, incorporating the tunnel junction into an edge emitting bipolar cascade laser, and finally the transition to a VCSEL structure is detailed. A novel approach prior to growing and characterizing BC VCSELs was to investigate bipolar cascade light emitting diodes which incorporate the microcavity designs and disentangles the VCSEL cavity effects from the microcavity. The best performing p-doped oxide aperture microcavity design was then used as the microcavity for 1-, 2-, and 3-stage BC …
Energy-Efficient Querying Of Wireless Sensor Networks, Christopher R. Mann
Energy-Efficient Querying Of Wireless Sensor Networks, Christopher R. Mann
Theses and Dissertations
Due to the distributed nature of information collection in wireless sensor networks and the inherent limitations of the component devices, the ability to store, locate, and retrieve data and services with minimum energy expenditure is a critical network function. Additionally, effective search protocols must scale efficiently and consume a minimum of network energy and memory reserves. A novel search protocol, the Trajectory-based Selective Broadcast Query protocol, is proposed. An analytical model of the protocol is derived, and an optimization model is formulated. Based on the results of analysis and simulation, the protocol is shown to reduce the expected total network …
Polarimeter Blind Deconvolution Using Image Diversity, David M. Strong
Polarimeter Blind Deconvolution Using Image Diversity, David M. Strong
Theses and Dissertations
This research presents an algorithm that improves the ability to view objects using an electro-optical imaging system with at least one polarization sensitive channel in addition to the primary channel. An innovative algorithm for detection and estimation of the defocus aberration present in an image is also developed. Using a known defocus aberration, an iterative polarimeter deconvolution algorithm is developed using a generalized expectation-maximization (GEM) model. The polarimeter deconvolution algorithm is extended to an iterative polarimeter multiframe blind deconvolution (PMFBD) algorithm with an unknown aberration. Using both simulated and laboratory images, the results of the new PMFBD algorithm clearly outperforms …
Finite Element Analysis Of Lamb Waves Acting Within A Thin Aluminum Plate, Sejin Han
Finite Element Analysis Of Lamb Waves Acting Within A Thin Aluminum Plate, Sejin Han
Theses and Dissertations
Structural health monitoring (SHM) is an emerging technology that can be used to identify, locate and quantify structural damages before failure. Among SHM techniques, Lamb waves have become widely used since they can cover large areas from one single location. Due to the development of various structural simulation programs, there is increasing interest in whether SHM data obtained from the simulation can be verified by experimentation. The objective of this thesis is to determine Lamb wave responses using SHM models in ABAQUS CAE(a Finite Element Analysis(FEA) program). These results are then compared to experimental results and theoretical predictions under isothermal …
Flight Dynamic Response Of Hale Aircraft To Kc-135 Flowfield, Amanda J. Devuono
Flight Dynamic Response Of Hale Aircraft To Kc-135 Flowfield, Amanda J. Devuono
Theses and Dissertations
This research effort examines the static effects of a KC-135 flowfield on a flexible winged Sensorcraft model. The KC-135 flowfield data is generated by a vortex lattice code and integrated into Sensorcraft model for analysis. Building on previous research, a refueling situation was modeled to note the effects of the Sensorcraft at varying locations within the flowfield. The Sensorcraft model was analyzed for both rigid and flexible wings as a means of comparision. Flowfield locations of interest were determined and trimmed conditions were computed for each flowfield location. Utilizing the trimmed condition and flowfield locations, the nonlinear set of EOM's …