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

Digital Commons Network™

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

Air Force Institute of Technology

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 2101 - 2130 of 5603

Full-Text Articles in Entire DC Network

Iron-Doped Zinc Selenide: Spectroscopy And Laser Development, Jonathan W. Evans Mar 2014

Iron-Doped Zinc Selenide: Spectroscopy And Laser Development, Jonathan W. Evans

Theses and Dissertations

We examine the quantum mechanics of optically active ions in crystals. Insight is developed which qualitatively explains the shape of the optical absorption and emission spectra of Fe2+ ions in II-VI materials. In addition to a discussion of the relevant theory, this work explores experimental techniques for absorption spectroscopy, laser-induced fluorescence spectroscopy, and upper-state lifetime measurements in detail. The data collected from these experiments are interpreted in the context of the theories developed herein. The theory and data are used to develop a simple model of the temperature dependence of the upper-state lifetime of Fe2+ ions in ZnSe. …


About Phase: Synthetic Aperture Radar And The Phase Retrieval Problem, Aaron A. Nelson Mar 2014

About Phase: Synthetic Aperture Radar And The Phase Retrieval Problem, Aaron A. Nelson

Theses and Dissertations

Synthetic aperture radar (SAR) uses relative motion to produce fine resolution images from microwave frequencies and is a useful tool for regular monitoring and mapping applications. Unfortunately, if target distance is estimated poorly, then phase errors are incurred in the data, producing a blurry reconstruction of the image. In this thesis, we introduce a new multistatic methodology for determining these phase errors from interferometry-inspired combinations of signals. To motivate this, we first consider a more general problem called phase retrieval, in which a signal is reconstructed from linear measurements whose phases are either unreliable or unavailable. We make significant theoretical …


Impact Of The Shodan Computer Search Engine On Internet-Facing Industrial Control System Devices, Roland C. Bodenheim Mar 2014

Impact Of The Shodan Computer Search Engine On Internet-Facing Industrial Control System Devices, Roland C. Bodenheim

Theses and Dissertations

The Shodan computer search engine crawls the Internet attempting to identify any connected device. Using Shodan, researchers identified thousands of Internet-facing devices associated with industrial controls systems (ICS). This research examines the impact of Shodan on ICS security, evaluating Shodan's ability to identify Internet-connected ICS devices and assess if targeted attacks occur as a result of Shodan identification. In addition, this research evaluates the ability to limit device exposure to Shodan through service banner manipulation. Shodan's impact was evaluated by deploying four high-interaction, unsolicited honeypots over a 55 day period, each configured to represent Allen-Bradley programmable logic controllers (PLC). All …


Improved Dictionary Formation And Search For Synthetic Aperture Radar Canonical Shape Feature Extraction, Matthew P. Crosser Mar 2014

Improved Dictionary Formation And Search For Synthetic Aperture Radar Canonical Shape Feature Extraction, Matthew P. Crosser

Theses and Dissertations

ATR requires detecting and estimating distinguishing characteristics of a target of interest. Radar data provides range and amplitude information; range distinguishes location relative to the radar whereas amplitude determines strength of reflectivity. Strong reflecting scattering features of targets are detected from a combination of radar returns, or radar PH data. Strong scatterers are modeled as canonical shapes (a plate, dihedral, trihedral, sphere, cylinder, or top-hat). Modeling the scatterers as canonical shapes takes the high dimensional radar PH from each scatterer and parameterizes the scatterer according to its location, size, and orientation. This thesis e ciently estimates the parameters of canonical …


Design, Fabrication And Testing Of Two Dimensional Radio Frequency Metamaterials, Russell P. Krones Mar 2014

Design, Fabrication And Testing Of Two Dimensional Radio Frequency Metamaterials, Russell P. Krones

Theses and Dissertations

This project focused on radio frequency (RF) metamaterials (MTM) structures using two different methods: wet etching copper (Cu) on insulating glass reinforced epoxy resin (FR4) and silver nano-particle ink printed SRR meta-atoms on photo paper (Ag on paper). Once the MTMs were fabricated, RF properties were measured using a 0-4 GHz stripline and the 2-18 GHz broad antenna near-field test and measurement range two dimensional focus beam system. Through electromagnetic (EM) material property extraction of these RF measurements, the EM properties of the MTM were also shown. Three tests were employed: scattering parameter measurements, near-field testing, and empty PPWG application …


A Test Methodology For Evaluating Cognitive Radio Systems, Jared J. Thompson Mar 2014

A Test Methodology For Evaluating Cognitive Radio Systems, Jared J. Thompson

Theses and Dissertations

The cognitive radio field currently lacks a standardized test methodology that is repeatable, flexible, and effective across multiple cognitive radio architectures. Furthermore, the cognitive radio field lacks a suitable framework that allows testing of an integrated cognitive radio system and not solely specific components. This research presents a cognitive radio test methodology, known as CRATM, to address these issues. CRATM proposes to use behavior-based testing, in which cognition may be measured by evaluating both primary user and secondary user performance. Data on behavior based testing is collected and evaluated. Additionally, a unique means of measuring secondary user interference to the …


Copper Doping Of Zinc Oxide By Nuclear Transmutation, Matthew C. Recker Mar 2014

Copper Doping Of Zinc Oxide By Nuclear Transmutation, Matthew C. Recker

Theses and Dissertations

This research verifies that neutron irradiation of zinc oxide leads to Cu-doping of the material by nuclear transmutation. After irradiation, both 65Zn and 69mZn were detected and positively identified. 65Zn was visible at all times while 69mZn was visible when the samples were measured within a few Zn-69m half-lifes. All decay paths of 65Zn lead to 65Cu and the detection of the 1115.5 keV characteristic gamma ray from this decay clearly indicated that 65Cu was being created. Previous electron paramagnetic resonance (EPR) spectroscopic results were replicated to determine the spectrum of copper impurities …


Wigner Distribution Functions As A Tool For Studying Gas Phase Alkali Metal Plus Noble Gas Collisions, Keith A. Wyman Mar 2014

Wigner Distribution Functions As A Tool For Studying Gas Phase Alkali Metal Plus Noble Gas Collisions, Keith A. Wyman

Theses and Dissertations

Wave packet propagation methods are used to compute scattering Wigner Distribution Functions (WDF) for the square well potential, square barrier potential, and the H+H2 and OH+CO, and several M+Ng collisions. The scattering WDF are used to interpret how probabilities flow among various potential energy surfaces as a function of time during a collision. Positive values of the scattering WDF correspond to the addition of probability to scatter into the state that corresponds to the asymptotic limit of the potential energy surface of interest. Negative values correspond to the loss of probability to scatter into the state that corresponds to the …


Application Of A Multi-Objective Network Model To A Combat Simulation Game: "The Drive On Metz" Case Study, Timothy D. Frawley Mar 2014

Application Of A Multi-Objective Network Model To A Combat Simulation Game: "The Drive On Metz" Case Study, Timothy D. Frawley

Theses and Dissertations

War games are routinely analyzed by the Department of Defense to study the players decision making process. This research develops a multicriteria model that enhances a war game players decision-making capability. The war game consists of a hexagonal-grid map of varying terrain that will be represent as a two-dimensional directed network. The network is obstructed by multiple enemy threats that expose a unit traversing the network to possible attack. The player is faced with the decision of choosing a route to a target node that balances the objectives of following the shortest path and maximizing the probability of success. A …


Complexity, Heuristic, And Search Analysis For The Games Of Crossings And Epaminondas, David W. King Jr. Mar 2014

Complexity, Heuristic, And Search Analysis For The Games Of Crossings And Epaminondas, David W. King Jr.

Theses and Dissertations

Games provide fertile research domains for algorithmic research. Often, game research helps solve real-world problems through the testing and refinement of search algorithms in game domains. Other times, game research finds limits for certain algorithms. For example, the game of Go proved intractable for the Min-Max with Alpha-Beta pruning algorithm leading to the popularity of Monte-Carlo based search algorithms. Although effective in Go, and game domains once ruled by Alpha-Beta such as Lines of Action, Monte-Carlo methods appear to have limits too as they fall short in tactical domains such as Hex and Chess. In a continuation of this type …


2013 Annual Report Of The Graduate School Of Engineering And Management, Air Force Institute Of Technology, Office Of Research And Sponsored Programs, Graduate School Of Engineering And Management, Afit Mar 2014

2013 Annual Report Of The Graduate School Of Engineering And Management, Air Force Institute Of Technology, Office Of Research And Sponsored Programs, Graduate School Of Engineering And Management, Afit

AFIT Documents

The Graduate School's Annual Report highlights research focus areas, new academic programs, faculty accomplishments and news, and provides top-level sponsor-funded research data and information.


Triplet Ground State Of The Neutral Oxygen-Vacancy Donor In Rutile Tio2, A. T. Brant, Eric M. Golden, Nancy C. Giles, Shan Yang, M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton Mar 2014

Triplet Ground State Of The Neutral Oxygen-Vacancy Donor In Rutile Tio2, A. T. Brant, Eric M. Golden, Nancy C. Giles, Shan Yang, M. A. R. Sarker, S. Watauchi, M. Nagao, I. Tanaka, D. A. Tryk, A. Manivannan, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) is used to investigate the triplet (S = 1) ground state of the neutral oxygen vacancy in bulk rutile TiO2 crystals. This shallow donor consists of an oxygen vacancy with two nearest-neighbor, exchange-coupled 3+ ions located along the [001] direction and equidistant from the vacancy. The spins of the two trapped electrons, one at each 3+ ion, align parallel to give the S = 1 state. These neutral oxygen vacancies are formed near 25 K in as-grown oxidized TiO2 crystals by illuminating with sub-band-gap 442 nm laser light. The angular dependence of the EPR …


Neutral Nitrogen Acceptors In Zno: The 67Zn Hyperfine Interactions, Eric M. Golden, S. M. Evans, Larry E. Halliburton, Nancy C. Giles Mar 2014

Neutral Nitrogen Acceptors In Zno: The 67Zn Hyperfine Interactions, Eric M. Golden, S. M. Evans, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR) is used to characterize the 67Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N−) initially present in the crystal are converted to their paramagnetic neutral charge state (N0) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N0 acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion …


Characterization Of Construction Material Properties Through Gamma Spectroscopy, X-Ray Fluorescence, And Hyper-Spectral Imagery For Background Correction Applications In Nuclear Detection, Jared D. Casebolt Mar 2014

Characterization Of Construction Material Properties Through Gamma Spectroscopy, X-Ray Fluorescence, And Hyper-Spectral Imagery For Background Correction Applications In Nuclear Detection, Jared D. Casebolt

Theses and Dissertations

Material identification through hyper-spectral imagery provides a potentially useful data input for background radiation prediction models for gamma spectrum correction in mobile nuclear detection applications. Traditional background correction methods which rely on prior information are often impractical in mobile detection. Prediction models could combine material information with spatial data to develop a suitable substitute to actual background radiation measurements. This research investigates the relationship hyper-spectral properties and natural radioactivity of construction materials. A selection of construction materials are analyzed using three instrumentation methods: 1) gamma-spectroscopy, 2) X-ray fluorescence (XRF), and 3) hyper-spectral imagery. Gamma-spectroscopy focuses on the presence of potassium …


Polarimetric Calibration And Characterization Of The Telops Field Portable Polarimetric-Hyperspectral Imager, Joel G. Holder Mar 2014

Polarimetric Calibration And Characterization Of The Telops Field Portable Polarimetric-Hyperspectral Imager, Joel G. Holder

Theses and Dissertations

The Telops polarimetric-hyperspectral imager combines polarimetric and hyperspectral technologies to enable enhanced scene characterization. The Defense Threat Reduction Agency funded research at AFIT to leverage this capability to provide more accurate scene information to radiation transport models that will allow for more effective location of radiation sources within a region of interest. To support the objectives of the DTRA effort, there is a requirement for highly accurate radiometric, polarimetric, and spectral data on a pixel-by-pixel basis. The complex nature of the Telops instrument combined with working in the thermal IR waveband makes achieving this accuracy a challenge. This thesis develops …


Comparative Analysis Of Reconstructed Image Quality In A Simulated Chromotomographic Imager, Ryan L. Tervo Mar 2014

Comparative Analysis Of Reconstructed Image Quality In A Simulated Chromotomographic Imager, Ryan L. Tervo

Theses and Dissertations

A hyperspectral chromotomographic instrument has been developed to determine the spatial and spectral distribution of a target. It does this by recording the dispersed images produced by a rotating direct vision prism with a high speed camera. The recorded images are processed through a tomographic reconstruction algorithm to produce a reconstructed hypercube. A physics-based system model was developed to investigate three areas. The first was how the prism angle selection and range of angles used impacted the reconstructed image quality. The second was an assessment of a new iterative reconstruction algorithm developed to remove artifacts produced in the Back Projection …


Band Gap Transition Studies Of U:Tho2 Using Cathodoluminescence, Joshua D. Reding Mar 2014

Band Gap Transition Studies Of U:Tho2 Using Cathodoluminescence, Joshua D. Reding

Theses and Dissertations

The Department of Defense has expressed interest in thorium dioxide (ThO2) and uranium dioxide (UO2) as possible candidates for use as special nuclear material in designing neutron detectors. Both materials have large neutron interaction cross sections. Uranium dioxide is particularly attractive due to its semiconducting properties and a relatively small band gap of 2 eV. Both materials fluoresce under ionizing radiation making them candidates for scintillating detectors. Three Ux:Th1-xO2 (x= 0.00, 0.01, 0.22) hydrothermally grown single crystals were examined using cathodoluminescence to interrogate the changing electronic properties of ThO2 as …


Range Finding With A Plenoptic Camera, Robert A. Raynor Mar 2014

Range Finding With A Plenoptic Camera, Robert A. Raynor

Theses and Dissertations

The plenoptic camera enables simultaneous collection of imagery and depth information by sampling the 4D light field. The light field is distinguished from data sets collected by stereoscopic systems because it contains images obtained by an N by N grid of apertures, rather than just the two apertures of the stereoscopic system. By adjusting parameters of the camera construction, it is possible to alter the number of these `subaperture images,' often at the cost of spatial resolution within each. This research examines a variety of methods of estimating depth by determining correspondences between subaperture images. A major finding is that …


Applicability Of Latent Dirichlet Allocation To Multi-Disk Search, George E. Noel, Gilbert L. Peterson Mar 2014

Applicability Of Latent Dirichlet Allocation To Multi-Disk Search, George E. Noel, Gilbert L. Peterson

Faculty Publications

Digital forensics practitioners face a continual increase in the volume of data they must analyze, which exacerbates the problem of finding relevant information in a noisy domain. Current technologies make use of keyword based search to isolate relevant documents and minimize false positives with respect to investigative goals. Unfortunately, selecting appropriate keywords is a complex and challenging task. Latent Dirichlet Allocation (LDA) offers a possible way to relax keyword selection by returning topically similar documents. This research compares regular expression search techniques and LDA using the Real Data Corpus (RDC). The RDC, a set of over 2400 disks from real …


An Experimental Evaluation Of Image Quality For Various Scenarios In A Chromotomographic System With A Spinning Prism, Kyle J. Dufaud Mar 2014

An Experimental Evaluation Of Image Quality For Various Scenarios In A Chromotomographic System With A Spinning Prism, Kyle J. Dufaud

Theses and Dissertations

A lab and eld based hyperspectral chromotomographic imager has been developed at the Air Force Institute of Technology. It is a prototype used to study the requirements for a space-based system. The imager uses a high speed visible band camera behind a direct-vision prism to image both spatial dimensions and the spectral dimension at the same time. Capturing all 3 simultaneously allows for the hyperspectral imaging of transient events. The prism multiplexes the spectral and spatial information, so tomographic reconstruction algorithms must be used to separate hyperspectral channels. Experiments were conducted to compare reconstructed image quality as a function of …


Air Force Institute Of Technology Research Report 2013, Office Of Research And Sponsored Programs, Graduate School Of Engineering And Management, Afit Jan 2014

Air Force Institute Of Technology Research Report 2013, Office Of Research And Sponsored Programs, Graduate School Of Engineering And Management, Afit

AFIT Documents

This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems Engineering and Management, Operational Sciences, Mathematics, Statistics and Engineering Physics.


Digital Display With Integrated Computing Circuit, Ronald S. Cok, John W. Harmer, Michael E. Miller Jan 2014

Digital Display With Integrated Computing Circuit, Ronald S. Cok, John W. Harmer, Michael E. Miller

AFIT Patents

A digital display device includes a display substrate; an array of pixels formed on the display substrate; an array of driving circuits located on the display substrate, each driving circuit electrically connected to one or more pixels for controlling a pixel current provided to each pixel; an array of computing circuits located on the display substrate, each computing circuit including circuits for signal or image processing and for communicating with neighboring computing circuits; a plurality of electrical conductors formed on the display substrate and connected to each of the driving circuits and digital computing circuits, wherein each computing circuit is …


Graduate School Of Engineering And Management Catalog 2014-2015, Graduate School Of Engineering And Management, Air Force Institute Of Technology Jan 2014

Graduate School Of Engineering And Management Catalog 2014-2015, 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.


Using Software-Based Decision Procedures To Control Instruction-Level Execution, William B. Kimball Dec 2013

Using Software-Based Decision Procedures To Control Instruction-Level Execution, William B. Kimball

AFIT Patents

An apparatus, method and program product are provided for securing a computer system. A digital signature of an application is checked, which is loaded into a memory of the computer system configured to contain memory pages. In response to finding a valid digital signature, memory pages containing instructions of the application are set as executable and memory pages other than those containing instructions of the application are set as non-executable. Instructions in executable memory pages are executed. Instructions in non-executable memory pages are prevented from being executed. A page fault is generated in response to an attempt to execute an …


Development Of A Resource Manager Framework For Adaptive Beamformer Selection, Jeremy P. Stringer Dec 2013

Development Of A Resource Manager Framework For Adaptive Beamformer Selection, Jeremy P. Stringer

Theses and Dissertations

Adaptive digital beamforming (DBF) algorithms are designed to mitigate the effects of interference and noise in the electromagnetic (EM) environment encountered by modern electronic support (ES) receivers. Traditionally, an ES receiver employs a single adaptive DBF algorithm that is part of the design of the receiver system. While the traditional form of receiver implementation is effective in many scenarios it has inherent limitations. This dissertation proposes a new ES receiver framework capable of overcoming the limitations of traditional ES receivers. The proposed receiver framework is capable of forming multiple, independent, simultaneous adaptive digital beams toward multiple signals of interest in …


Timing And Spectroscopy Requirements For A Plastic Scintillating Fiber Bundle Time-Of-Flight Neutron Spectrometer, Paul A. Clement Dec 2013

Timing And Spectroscopy Requirements For A Plastic Scintillating Fiber Bundle Time-Of-Flight Neutron Spectrometer, Paul A. Clement

Theses and Dissertations

The design parameters of a Time-of-Flight (TOF) neutron spectrometer composed of BCF-12 plastic scintillating fibers were investigated. A GEANT4 transport model was developed for analyzing the interaction of 2.5 MeV neutrons with a 14 x 14 BCF-12 fiber bundle. The bundle simulation demonstrated that 0.359% of all neutrons incident on the bundle will double scatter. The timing and data collection e efficiencies of a Tektronix DPO7104 series digital oscilloscope were examined to determine the signal processing requirements for future fiber bundle measurements. The minimum detectable neutron energy was computed by taking into account the bundle scintillation e efficiency, light collection …


Electronic And Physical Characterization Of Hydrothermally Grown Single Crystal Tho2, Tony D. Kelly Ii Dec 2013

Electronic And Physical Characterization Of Hydrothermally Grown Single Crystal Tho2, Tony D. Kelly Ii

Theses and Dissertations

Actinide single crystals are important to the fabrication of next generation electronic devices that could possibly have radiation with the atmosphere and surroundings. Th02 single crystals were obtained previous to this work by hydrothermal synthesis. As these crystals were the first of their kind, the geometric and electric structure of the crystals needed to be extracted. The valence and conduction bands were studied in order to ascertain the band gap using ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES). The unoccupied structure was further characterized using x-ray absorption near edge structure (XANES) and relativistic, real-space Green's functions calculations. The …


Network Interdependency Modeling For Risk Assessment On Built Infrastructure Systems, Vhance V. Valencia Dec 2013

Network Interdependency Modeling For Risk Assessment On Built Infrastructure Systems, Vhance V. Valencia

Theses and Dissertations

As modern infrastructures become more interconnected, the decision-making process becomes more difficult because of the increased complexity resulting from infrastructure interdependencies. Simulation and network modeling provide a way to understand system behavior as a result of interdependencies. One area within the asset management literature that is not well covered is infrastructure system decay and risks associated with that decay. This research presents an enhanced version of Haimes' input-output inoperability model (IIM) in the analysis of built infrastructure systems. Previous applications of the IIM characterized infrastructure at the national level utilizing large economic databases. This study develops a three-phased approach that …


Situational Awareness/Triage Tool For Use In A Chemical, Biological, Radiological Nuclear Explosive (Cbrne) Environment, John N. Scarlett, Heather L. Gallup, David A. Smith Dec 2013

Situational Awareness/Triage Tool For Use In A Chemical, Biological, Radiological Nuclear Explosive (Cbrne) Environment, John N. Scarlett, Heather L. Gallup, David A. Smith

AFIT Patents

A method of managing patient care and emergency response following a Chemical, Biological, Radiological, or Nuclear Explosive (CBRNE) attack and maintaining compliance with the Health Insurance Portability and Accountability Act (HIPAA). The method including identifying each patient with a unique patient identifier, the identifier based upon the geospatial location of the patient, the geospatial location including at least the latitude and longitude of the patient when first treated, the unique patient identifier being part of patient data. Providing a collection point of patient data to form a patient data database where in the patient location data may be used to …


Aerodynamic Performance And Particle Image Velocimetery Of Piezo Actuated Biomimetic Manduca Sexta Engineered Wings Towards The Design And Application Of A Flapping Wing Flight Vehicle, Anthony M. Deluca Dec 2013

Aerodynamic Performance And Particle Image Velocimetery Of Piezo Actuated Biomimetic Manduca Sexta Engineered Wings Towards The Design And Application Of A Flapping Wing Flight Vehicle, Anthony M. Deluca

Theses and Dissertations

Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing element model (BEM). An …