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Articles 1981 - 2010 of 5602
Full-Text Articles in Entire DC Network
Experimental Uncertainty Associated With Traveling Wave Excitation, Geofrey S. Cox
Experimental Uncertainty Associated With Traveling Wave Excitation, Geofrey S. Cox
Theses and Dissertations
This dissertation research produces the experimental techniques required to evaluate mistuning in any rotor. Within operation, a rotor is subjected to a unique pattern of frequencies acting to excite the rotor. Utilizing traveling wave excitation, a rotor's critical frequencies and the respective excitation pattern are reproduced. Individual rotor blade frequency response functions are evaluated and statistically analyzed. The experimental results serve to not only verify the degree to which a rotor is mistuned, but also to provide an indication of the forced response amplification the mistuning induces. Within the experiment, definitive specifications were developed to ensure peak rotor responses. Numerical …
Optimal Control Of Fully Routed Air Traffic In The Presence Of Uncertainty And Kinodynamic Constraints, Christopher D. Arendt
Optimal Control Of Fully Routed Air Traffic In The Presence Of Uncertainty And Kinodynamic Constraints, Christopher D. Arendt
Theses and Dissertations
A method is presented to extend current graph-based Air Traffic Management optimization frameworks. In general, Air Traffic Management is the process of guiding a finite set of aircraft, each along its pre-determined path within some local airspace, subject to various physical, policy, procedural and operational restrictions. This research addresses several limitations of current graph-based Air Traffic Management optimization methods by incorporating techniques to account for stochastic effects, physical inertia and variable arrival sequencing. In addition, this research provides insight into the performance of multiple methods for approximating non-differentiable air traffic constraints, and incorporates these methods into a generalized weighted-sum representation …
Epaminondas: Exploring Combat Tactics, David W. King, Gilbert L. Peterson
Epaminondas: Exploring Combat Tactics, David W. King, Gilbert L. Peterson
Faculty Publications
Epaminondas is a two-person, zero-sum strategy game that combines long-term strategic play with highly tactical move sequences. The game has two unique features that make it stand out from other games. The first feature is the creation of phalanxes, which are groups of pieces that can move as a whole unit. As the number of pieces in a phalanx increases, the mobility and capturing power of the phalanx also increases. The second feature differs from many other strategy games: when a player makes a crossing, a winning move in the game, the second player has an opportunity to respond. This …
Observation Of Heavy- And Light-Hole Split Direct Bandgap Photoluminescence From Tensile-Strained Gesn (0.03% Sn), Thomas R. Harris, Yung Kee Yeo, Mee-Yi Ryu, Richard T. Beeler, John Kouvetakis
Observation Of Heavy- And Light-Hole Split Direct Bandgap Photoluminescence From Tensile-Strained Gesn (0.03% Sn), Thomas R. Harris, Yung Kee Yeo, Mee-Yi Ryu, Richard T. Beeler, John Kouvetakis
Faculty Publications
Temperature- (T-) and laser power-dependent photoluminescence (PL) measurements have been made for the tensile-strained, undoped GeSn (0.03% Sn) film grown on Si substrate. The PL results show not only clear strain-split direct bandgap transitions to the light-hole (LH) and heavy-hole (HH) bands at energies of 0.827 and 0.851 eV at 10 K, respectively, but also clearly show both strong direct and indirect bandgap related PL emissions at almost all temperatures, which are rarely observed. This split of PL emissions can be directly observed only at low T and moderate laser power, and the two PL peaks merge into one broad …
A Method To Develop Neck Injury Criteria To Aid Design And Test Of Escape Systems Incorporating Helmet Mounted Displays, Jeffrey C. Parr
A Method To Develop Neck Injury Criteria To Aid Design And Test Of Escape Systems Incorporating Helmet Mounted Displays, Jeffrey C. Parr
Theses and Dissertations
HMDs are becoming common human-machine interface equipment in manned military flight, but introducing this equipment into the overall aircraft escape system poses new and significant system design, development, and test concerns. Although HMDs add capabilities, which improve operator performance, the increased capability is often accompanied by increased head supported mass. The increased mass can amplify the risk of pilot neck injury during ejection when compared to lighter legacy helmets. Currently no adequate USAF neck injury criteria exist to effectively guide the requirements, design, and test of escape systems for pilots with HMDs. This research effort presents a novel method to …
Initial Capabilities Documents: A 10-Year Retrospective Of Tools, Methodologies, And Best Practices, Bryan D. Main, Michael P. Kretser, Joshua Shearer, Darrin A. Ladd
Initial Capabilities Documents: A 10-Year Retrospective Of Tools, Methodologies, And Best Practices, Bryan D. Main, Michael P. Kretser, Joshua Shearer, Darrin A. Ladd
Faculty Publications
The Joint Capabilities Integration and Development System (JCIDS) is 10 years old and ripe for review. A central output document of the JCIDS process is an Initial Capabilities Document (ICD) used by the Department of Defense to define gaps in a functional capability area and define new capabilities required. The research team analyzed 10 years of ICDs to identify methods and trends. The team found that several methodologies were favored and a convergence emerged in format and necessary content. Additionally, potential shortfalls in current best practices of interest to implementers and decision makers are identified. Guidelines and best practices are …
Narratives As A Fundamental Component Of Consciousness, Sandra L. Vaughan, Robert F. Mills, Michael R. Grimaila, Gilbert L. Peterson, Steven K. Rogers
Narratives As A Fundamental Component Of Consciousness, Sandra L. Vaughan, Robert F. Mills, Michael R. Grimaila, Gilbert L. Peterson, Steven K. Rogers
Faculty Publications
In this paper, we propose a conceptual architecture that models human (spatially-temporally-modally) cohesive narrative development using a computer representation of quale properties. Qualia are proposed to be the fundamental "cognitive" components humans use to generate cohesive narratives. The engineering approach is based on cognitively inspired technologies and incorporates the novel concept of quale representation for computation of primitive cognitive components of narrative. The ultimate objective of this research is to develop an architecture that emulates the human ability to generate cohesive narratives with incomplete or perturbated information.
Windows Memory Forensic Data Visualization, James B. Baum
Windows Memory Forensic Data Visualization, James B. Baum
Theses and Dissertations
Modern criminal investigators face an increasing number of computer-related crimes that require the application of digital forensic science. The major challenge facing digital forensics practitioners is the complicated task of acquiring an understanding of the digital data residing in electronic devices. Currently, this task requires significant experience and background to correctly aggregate the data their tools provide from the digital artifacts. Most of the tools available present their results in text files or tree lists. It is up to the practitioner to mentally capture a global understanding of the state of the device at the time of seizure and find …
Imaging Fourier Transform Spectroscopy Of The Boundary Layer Plume From Laser Irradiated Polymers And Carbon Materials, Roberto I. Acosta
Imaging Fourier Transform Spectroscopy Of The Boundary Layer Plume From Laser Irradiated Polymers And Carbon Materials, Roberto I. Acosta
Theses and Dissertations
Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid wave infrared (MWIR) imaging Fourier transform infrared (FTIR) spectrometer. Polymer and graphite targets were irradiated with a 1.064 µm Nd:YAG and a 1.07 µm ytterbium continuous wave (CW) fiber lasers respectively. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emissions from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900 cm-1 and 4000 cm-1. A single-layer radiative …
An Analysis Of The Impact Of Variation In Mean Time Between Demand On Air Force Fleet Level Aircraft Parts Inventories, Andrew J. Berger, Caleb S. Murphy
An Analysis Of The Impact Of Variation In Mean Time Between Demand On Air Force Fleet Level Aircraft Parts Inventories, Andrew J. Berger, Caleb S. Murphy
Theses and Dissertations
This thesis researched the accuracy of demand forecasting and impact of demand variation on requirements definition for Air Force aircraft secondary items. Specifically, this thesis sought to answer three questions: How does the Air Force calculate item requirements? , How accurate is the current system at predicting future item requirements? , and How do variations in predicted demand change item requirements? The literature review described the Air Force supply system for aircraft secondary items. Analysis into current demand forecast accuracy found that the level of error between actual and predicted historic demand was as high as 92% for the items …
Different Formulations Of The Orthogonal Array Problem And Their Symmetries, Andrew J. Geyer
Different Formulations Of The Orthogonal Array Problem And Their Symmetries, Andrew J. Geyer
Theses and Dissertations
Modern statistical experiments routinely feature a large number of input variables that can each be set to a variety of different levels. In these experiments, output response changes as a result of changes in the individual factor level settings. Often, an individual experimental run can be costly in time, money or both. Therefore, experimenters generally want to gain the desired information on factor effects from the smallest possible number of experimental runs. Orthogonal arrays provide the most desirable designs. However, finding orthogonal arrays is a very challenging problem. There are numerous integer linear programming formulations (ILP) in the literature whose …
Android Based Behavioral Biometric Authentication Via Multi-Modal Fusion, Anthony J. Grenga
Android Based Behavioral Biometric Authentication Via Multi-Modal Fusion, Anthony J. Grenga
Theses and Dissertations
Because mobile devices are easily lost or stolen, continuous authentication is extremely desirable for them. Behavioral biometrics provides non-intrusive continuous authentication that has much less impact on usability than active authentication. However single-modality behavioral biometrics has proven less accurate than standard active authentication. This thesis presents a behavioral biometric system that uses multi-modal fusion with user data from touch, keyboard, and orientation sensors. Testing of ve users shows that fusion of modalities provides more accurate authentication than each individual modalities by itself. Using the BayesNet classification algorithm, fusion achieves False Acceptance Rate (FAR) and False Rejection Rate (FRR) values of …
Non-Linear Optimization Applied To Angle-Of-Arrival Satellite-Based Geolocation, Stephen D. Hartzell
Non-Linear Optimization Applied To Angle-Of-Arrival Satellite-Based Geolocation, Stephen D. Hartzell
Theses and Dissertations
Geolocation is a common application for satellite systems. This involves estimating an object's location (herein called the subject) based on noisy satellite data. Many geolocation methods exist; however, none are tailored specifically for the unique problems faced by satellite systems. Some satellites are so far from the subject being localized that by the time the satellite receives a signal from the subject it might have moved appreciably. Furthermore, some satellites or terrestrial sensors may be much closer to the subject than others. Therefore, sensors may need to be weighted based upon their distance to the subject being localized. In addition, …
Enhanced Polarimetric Radar Imaging Using Cross-Channel Coupling Constraints, Andrea E. Perhai
Enhanced Polarimetric Radar Imaging Using Cross-Channel Coupling Constraints, Andrea E. Perhai
Theses and Dissertations
Data for a scene of interest may be collected over multiple polarization channels. In the case of polarimetric synthetic aperture radar images, regularization techniques are typically applied independently to each polarimetric channel. However, independent processing does not account for cross-channel coupling and may corrupt the polarimetric information in the signals. Recent consideration of joint enhancement techniques has shown promising results for multi- channel datasets with similar regions of signal magnitude and/or phase. However, in the case of polarimetric SAR data, scattering may be present in some channels and not in others. This thesis mathematically formulates multi-channel sparse imaging for polarimetric …
Finite Element Analysis Modeling Of Chemical Vapor Deposition Of Silicon Carbide, Brandon M. Allen
Finite Element Analysis Modeling Of Chemical Vapor Deposition Of Silicon Carbide, Brandon M. Allen
Theses and Dissertations
Fiber-reinforced silicon carbide (SiC) composite materials are important for many applications due to their high temperature strength, excellent thermal shock and impact resistance, high hardness, and good chemical stability. The microstructure and phase composition of SiC composites can be tailored by fiber surface modification, the process parameters, and/or fiber preform architecture. One process by which SiC composites can be produced is chemical vapor deposition (CVD). This thesis primarily focuses on mass transport by gas-phase flow and diffusion, chemical reaction in gas phase and on solid surfaces, and thin film formation on curved surfaces, which are fundamental to the CVD process. …
Advanced Composite Air Frame Life Cycle Cost Estimating, Mohamed M. Al Romaihi
Advanced Composite Air Frame Life Cycle Cost Estimating, Mohamed M. Al Romaihi
Theses and Dissertations
Because of their versatility, advanced composite materials are being used at an increasing rate in the manufacturing of aircraft, as well as other products, such as autos, sporting goods, and medical products. Airframe structure materials used throughout aerospace manufacturing processes consist of significantly greater percentages of advanced composite materials. However, these manufacturing processes and the associated reduction in part counts are not considered in the aircraft procurement and life cycle cost (LCC) management processes in the United States Air Force (USAF) community or the Department of Defense (DoD). This situation led the leaders of USAF and DoD to restudy the …
The Scattering Of Partially Coherent Electromagnetic Beam Illumination From Statistically Rough Surfaces, Mark F. Spencer
The Scattering Of Partially Coherent Electromagnetic Beam Illumination From Statistically Rough Surfaces, Mark F. Spencer
Theses and Dissertations
Much of the rough surface scattering theory developed to date considers only the effects of fully coherent and fully incoherent illumination in the formation of solutions— a problem studied in earnest since the late 1800’s. In response, this dissertation extends the theory currently available in modeling rough surface scattering to include the effects of partially coherent illumination. Such illumination plays a pivotal role in our understanding of active-illumination systems, similar to those found in directed-energy and remote-sensing applications, which use the light scattered from distant targets for tactical purposes. Specifically, this dissertation uses the physical optics approximation (Kirchhoff boundary conditions) …
The Prospect Of Responsive Spacecraft Using Aeroassisted, Trans-Atmospheric Maneuvers, Robert A. Bettinger
The Prospect Of Responsive Spacecraft Using Aeroassisted, Trans-Atmospheric Maneuvers, Robert A. Bettinger
Theses and Dissertations
Comprised of exo- and trans-atmospheric trajectory segments, atmospheric re-entry represents a complex dynamical event which traditionally signals the mission end-of-life for low-Earth orbit spacecraft. Transcending this paradigm, atmospheric re-entry can be employed as a means of operational maneuver whereby aerodynamic forces can be exploited to create an aeroassisted maneuver. Utilizing a notional trans-atmospheric, lifting re-entry vehicle with L/D =6, the first phase of research demonstrates the terrestrial reachability potential for skip entry aeroassisted maneuvers. By overflying a geographically diverse set of ground targets, comparative analysis indicates a significant savings in delta V expenditure for skip entry compared with exo-atmospheric maneuvers. …
Malware Target Recognition, Thomas E. Dube, Richard A. Raines, Steven K. Rogers
Malware Target Recognition, Thomas E. Dube, Richard A. Raines, Steven K. Rogers
AFIT Patents
A method, apparatus and program product are provided to recognize malware in a computing environment having at least one computer. A sample is received. An automatic determination is made by the at least one computer to determine if the sample is malware using static analysis methods. If the static analysis methods determine the sample is malware, dynamic analysis methods are used by the at least one computer to automatically determine if the sample is malware. If the dynamic analysis methods determine the sample is malware, the sample is presented to a malware analyst to adjudicate the automatic determinations of the …
Broadband, Non-Destructive Characterisation Of Pec-Backed Materials Using A Dual-Ridged-Waveguide Probe, Milo W. Hyde Iv, Michael J. Havrilla
Broadband, Non-Destructive Characterisation Of Pec-Backed Materials Using A Dual-Ridged-Waveguide Probe, Milo W. Hyde Iv, Michael J. Havrilla
Faculty Publications
A new probe which utilises a dual-ridged waveguide to provide broadband, non-destructive (ND) material characterisation measurements of a perfect electric conductor (PEC)-backed material is introduced. The new probe possesses a bandwidth similar to existing coaxial probes and is structurally robust like rectangular waveguide probes. The combinations of these two qualities make it especially attractive for ND inspection/evaluation applications in the field. The theoretical development of the dual-ridged-waveguide probe is discussed. A magnetic field integral equation is derived by applying Love’s equivalence theorem and enforcing the continuity of transverse fields at the dual-ridged-waveguide aperture. The magnetic field integral equation is then …
Copper Doping Of Zno Crystals By Transmutation Of 64Zn To 65Cu: An Electron Paramagnetic Resonance And Gamma Spectroscopy Study, Matthew C. Recker, John W. Mcclory, Maurio S. Holston, Eric M. Golden, Nancy C. Giles, Larry E. Halliburton
Copper Doping Of Zno Crystals By Transmutation Of 64Zn To 65Cu: An Electron Paramagnetic Resonance And Gamma Spectroscopy Study, Matthew C. Recker, John W. Mcclory, Maurio S. Holston, Eric M. Golden, Nancy C. Giles, Larry E. Halliburton
Faculty Publications
Transmutation of 64Zn to 65Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the 65Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of 64Zn nuclei to 65Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu2+ ions (where 63Cu and 65 …
User Identification And Authentication Using Multi-Modal Behavioral Biometrics, Kyle O. Bailey, James S. Okolica, Gilbert L. Peterson
User Identification And Authentication Using Multi-Modal Behavioral Biometrics, Kyle O. Bailey, James S. Okolica, Gilbert L. Peterson
Faculty Publications
Biometric computer authentication has an advantage over password and access card authentication in that it is based on something you are, which is not easily copied or stolen. One way of performing biometric computer authentication is to use behavioral tendencies associated with how a user interacts with the computer. However, behavioral biometric authentication accuracy rates are worse than more traditional authentication methods. This article presents a behavioral biometric system that fuses user data from keyboard, mouse, and Graphical User Interface (GUI) interactions. Combining the modalities results in a more accurate authentication decision based on a broader view of the user's …
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Investr: An R Package For Inverse Estimation, Brandon M. Greenwell, Christine M. Schubert Kabban
Faculty Publications
Inverse estimation is a classical and well-known problem in regression. In simple terms, it involves the use of an observed value of the response to make inference on the corresponding unknown value of the explanatory variable. To our knowledge, however, statistical software is somewhat lacking the capabilities for analyzing these types of problems. In this paper, we introduce investr (which stands for inverse estimation in R), a package for solving inverse estimation problems in both linear and nonlinear regression models.
Toward Automating Web Protocol Configuration For A Programmable Logic Controller Emulator, Deanna R. Fink
Toward Automating Web Protocol Configuration For A Programmable Logic Controller Emulator, Deanna R. Fink
Theses and Dissertations
Industrial Control Systems (ICS) remain vulnerable through attack vectors that exist within programmable logic controllers (PLC). PLC emulators used as honeypots can provide insight into these vulnerabilities. Honeypots can sometimes deter attackers from real devices and log activity. A variety of PLC emulators exist, but require manual figuration to change their PLC pro le. This limits their flexibility for deployment. An automated process for configuring PLC emulators can open the door for emulation of many types of PLCs. This study investigates the feasibility of creating such a process. The research creates an automated process for figuring the web protocols of …
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Lu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Lu, Lu Wang, Wai-Ning Mei, Peter A. Dowben
Faculty Publications
The four dopants (Nd, Gd, Dy, and Er) substitutionally occupy the Li+ sites in lithium tetraborate (Li2B4O7: RE) glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 Å, depending on the rare earth. The inverse relationship between the RE-O coordination distance and rare earth (RE) atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE …
Multi-Objective Optimization Of Dead-Reckoning Error Thresholds For Virtual Environments, Jeremy R. Millar, Douglas D. Hodson, Gary B. Lamont, Gilbert L. Peterson
Multi-Objective Optimization Of Dead-Reckoning Error Thresholds For Virtual Environments, Jeremy R. Millar, Douglas D. Hodson, Gary B. Lamont, Gilbert L. Peterson
Faculty Publications
Design trade-offs between state consistency and system response time are commonplace in virtual environments. Systems typically rely on predictive consistency algorithms such as dead-reckoning to control consistency and response time. Dead-reckoning error threshold selection determines the consistency/response time trade-off. We extend this trade-off space to explicitly account for the concept of system fairness. We derive a multi-objective optimization problem and apply multi-objective evolutionary algorithms to solve for Pareto optimal error thresholds. Abstract ©2014 IEEE.
Adverse Impacts Of Furlough Programs On Employee Work Rate And Organizational Productivity, Adedeji B. Badiru
Adverse Impacts Of Furlough Programs On Employee Work Rate And Organizational Productivity, Adedeji B. Badiru
Faculty Publications
This article is primarily a research-provoking exposition against the management approach used in the 2013 government furlough program. It is intended to prompt potentially productive research investigations on the impact of personnel furloughs, particularly on defense acquisition programs. Defense acquisition programs are time-sensitive and systems oriented. What appears as a minor delay in one unit of an acquisition life cycle can lead to long-term encumbrances within the entire defense system, resulting in enormous cost escalation. Pertinent analytical techniques/methodologies are provided to illustrate potential pathways for further research studies of furloughs and how they adversely impact organizational productivity. The author’s intent …
Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal
Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal
Faculty Publications
Thermospheric density impacts satellite position and lifetime through atmospheric drag. More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model, can decrease model density errors. This paper improves the model of Burke et al. (2009) to model thermospheric temperatures using the magnetospheric convective electric field as a driver. In better alignment with Air Force satellite tracking operations, we model the arithmetic mean temperature, T 1/2, defined by the Jacchia (1977) model as the mean of the daytime maximum and nighttime minimum exospheric temperatures occurring in opposite hemispheres at a …
Optimization Of Graphene Sensors To Detect Biological Warfare Agents, Matthew J. Quinton
Optimization Of Graphene Sensors To Detect Biological Warfare Agents, Matthew J. Quinton
Theses and Dissertations
The Defense Threat Reduction Agency and the Air Force Office of Scientific Research require sensors to detect biological agents better, faster, and cheaper. This research explores the use of graphene functionalized with single strand deoxyribonucleic acid (ssDNA) aptamers as a detection method for the Sterne strain of Bacillus anthracis. This research is interesting because of the unique electrical and chemical binding properties of graphene and its interaction with ssDNA and DNA. The interactions of graphene functionalized with ssDNA in response to B. anthracis spores, non-complimentary and complimentary DNA were explored in static and dynamic aqueous environments with indirect complimentary binding …
Radio Frequency Emitter Geolocation Using Cubesats, Andrew J. Small
Radio Frequency Emitter Geolocation Using Cubesats, Andrew J. Small
Theses and Dissertations
The ability to locate an RF transmitter is a topic of growing interest for civilian and military users alike. Geolocation can provide critical information for the intelligence community, search and rescue operators, and the warfighter. The technology required for geolocation has steadily improved over the past several decades, allowing better performance at longer baseline distances between transmitter and receiver. The expansion of geolocation missions from aircraft to spacecraft has necessitated research into how emerging geolocation methods perform as baseline distances are increased beyond what was previously considered. The CubeSat architecture is a relatively new satellite form which could enable small-scale, …