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Articles 1471 - 1500 of 5699
Full-Text Articles in Engineering
Space-Based Maneuver Detection And Characterization Using Multiple Model Adaptive Estimation, Justin D. Katzovitz
Space-Based Maneuver Detection And Characterization Using Multiple Model Adaptive Estimation, Justin D. Katzovitz
Theses and Dissertations
An increasingly congested space environment requires real-time and dynamic space situational awareness (SSA) on both domestic and foreign space objects in Earth orbits. Current statistical orbit determination (SOD) techniques are able to estimate and track trajectories for cooperative spacecraft. However, a non-cooperative spacecraft performing unknown maneuvers at unknown times can lead to unexpected changes in the underlying dynamics of classical filtering techniques. Adaptive estimation techniques can be utilized to build a bank of recursive estimators with different hypotheses on a system's dynamics. The current study assesses the use of a multiple model adaptive estimation (MMAE) technique for detecting and characterizing …
Quasi-Static Nonlinear Analysis Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Kyle D. Moore
Quasi-Static Nonlinear Analysis Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Kyle D. Moore
Theses and Dissertations
Due to the many drawbacks associated with a traditional lighter than air vehicle (LTAV), there is a desire for a LTAV which generates lift from an internal vacuum. To date, two feasible designs (the icosahedron and the hexakis icosahedron) for this so called vacuum lighter than air vehicle (VLTAV) have been studied at the Air Force Institute of Technology (AFIT). This research looks to show the feasibility of a new design for a VLTAV, the celestial icosahedron. This research includes a boundary condition study which proves the symmetric nature of the celestial icosahedron's frame with laterally constrained and unconstrained vertices. …
Navigation Using Vector And Tensor Measurements Of The Earth's Magnetic Anomaly Field, Lauren A. Mount
Navigation Using Vector And Tensor Measurements Of The Earth's Magnetic Anomaly Field, Lauren A. Mount
Theses and Dissertations
This research explores the viability of using a navigation system that relies on measurements of the magnetic anomaly field as an alternative to GPS navigation. Previous research has been conducted on developing a navigation system using the intensity of the Earth's magnetic anomaly field as an alternative signal. This research focuses on using vector and tensor measurements, as opposed to scalar measurements of the anomaly field, as a means of obtaining accurate position and orientation solutions. This paper presents two navigation systems. The first uses an Extended Kalman Filter (EKF) with vector measurements of the magnetic anomaly field to aid …
Effects Of Position Uncertainty On Passive Multistatic Sar Resolution Measures, Duy K. Nguyen
Effects Of Position Uncertainty On Passive Multistatic Sar Resolution Measures, Duy K. Nguyen
Theses and Dissertations
Given numerous exciting potentials including substantial cost savings, passive multistatic synthetic aperture radar (PMSAR) has been gaining more attention in the radar community. However, PMSAR research efforts such as emitters of opportunity selection thus far have not considered radar position uncertainty. Seeking to fill this knowledge gap, we run Monte Carlo trials to simulate transmitter position uncertainty and examine the effects on the multistatic resolution of radar sets of different geometries, center frequencies and bandwidths. By monitoring the 3dB contour of the multistatic point spread function, we find that the multistatic resolution worsens on average and the data spread grows …
They're Only Nuclear Weapons: An Exploratory Analysis Of Safety Climate Within The Nuclear Enterprise, Brandon M. Clements
They're Only Nuclear Weapons: An Exploratory Analysis Of Safety Climate Within The Nuclear Enterprise, Brandon M. Clements
Theses and Dissertations
By possessing nuclear weapons, the United States Air Force is inherently exposed to extreme safety concerns. With multiple setbacks in recent years (e.g., unauthorized transport of nuclear weapons, cheating scandals, and career dissatisfaction), some have begun to wonder how safe the nuclear enterprise truly is. Building upon the concept of safety climate, this study explores safety climate constructs and trends associated with current nuclear maintenance safety climate survey data.
Sentiment Analysis Of Twitter Data, Evan L. Munson
Sentiment Analysis Of Twitter Data, Evan L. Munson
Theses and Dissertations
The rapid expansion and acceptance of social media has opened doors into users’ opinions and perceptions that were never as accessible as they are with today's prevalence of mobile technology. Harvested data, analyzed for opinions and sentiment can provide powerful insight into a population. This research utilizes Twitter data due to its widespread global use, in order to examine the sentiment associated with tweets. An approach utilizing Twitter #hashtags and Latent Dirichlet Allocation topic modeling were utilized to differentiate between tweet topics. A lexicographical dictionary was then utilized to classify sentiment. This method provides a framework for an analyst to …
The Developmental Test Scheduling Problem, Joseph E. Schoenbeck
The Developmental Test Scheduling Problem, Joseph E. Schoenbeck
Theses and Dissertations
Developmental testing of aircraft systems in the United States Air Force requires a complex set of resources for each test. The optimal scheduling of those resources is the job of the 412th Test Wing at Edwards Air Force Base. With more than 20 different Combined Task Forces requesting resources for roughly 300 flying missions each week, manual scheduling is a difficult task. The current process takes a team of schedulers several days to get a workable result from which they can start tailoring the final schedule. While concepts and techniques can be taken from industry scheduling problems, the body of …
Aerial Port Of The Future: Developing Paperless Operations, Peter J. Williams
Aerial Port Of The Future: Developing Paperless Operations, Peter J. Williams
Theses and Dissertations
Air Mobility Command (AMC) is combatting manning mismatches with antiquated processes and equipment in Aerial Port operations, and has chosen to address these issues through an initiative called “Aerial Port of the Future.” This initiative is designed to understand challenges in Aerial Ports and implement technological tools, where appropriate, to aid AMC Airmen in their duties of transporting goods and personnel through military channels. Oftentimes, personnel are forced to utilize technology that may not meet their needs, and in turn may resist implementation of the imposed technology. Therefore, first, this research identifies potential technologies designed to improve Aerial Port efficiency …
Assessing The Reliability Of The B-1b Lancer Using Survival Analysis, Francisco J. Rodriguez
Assessing The Reliability Of The B-1b Lancer Using Survival Analysis, Francisco J. Rodriguez
Theses and Dissertations
During the 2017 posture statement to the US Senate Armed Services Committee, the Secretary of the Air Force and Chief of Staff of the Air Force stated the Air Force suffers from shrinking aircraft inventory, aging aircraft fleets, and flying beyond the expected service life. These trends are not an exception to the B-1B Lancer, which has been in service since 1986. Recently, the B-1B Lancer has maintained the lowest mission capable (MC) rates of 47.7 percent. The purpose of this research is to explore the failure rates of the B-1B Lancer using survival analysis that investigates the failure behavior …
Utilizing Supercomputing To Analyze Risks Of An Emergent Large-Scale Debris Field In Low Earth Orbit, David J. Buehler
Utilizing Supercomputing To Analyze Risks Of An Emergent Large-Scale Debris Field In Low Earth Orbit, David J. Buehler
Theses and Dissertations
The likelihood of on-orbit breakups, whether spontaneous or the result of collision, will likely continue to grow as the barriers of entry to and use of space are reduced. In all orbital regimes, especially low Earth orbit (LEO), preparation to respond quickly when the next breakup occurs is critical. This research utilizes high-performance parallel computation along with python-driven Systems Tool Kit (STK) to model a large-scale on-orbit breakup in LEO, with the goal of returning data in less than 90 minutes. The breakup is characterized by the National Aeronautics and Space Administration (NASA) EVOLVE 4.0 breakup model and is both …
An Analysis Of Aircraft Operating And Support Cost Element Structures, Garrett B. O'Hanlon
An Analysis Of Aircraft Operating And Support Cost Element Structures, Garrett B. O'Hanlon
Theses and Dissertations
As the cost of DoD Weapon Systems continue to increase, the ability to more accurately predict the Operating and Support (O&S) costs for the various weapon systems has become more vital for long run affordability. The investigation into the O&S arena has been overshadowed by the research and development (R&D) and acquisition fields. This research focuses on the O&S portion of the total life cycle costs, specifically the OSD-CAPE Cost Element Structure (CES) elements and sub-elements. The research investigates seven categories of 52 aircrafts and their cost expenditures within the CES from the years 1996-2016. The first portion of the …
The Effect Of Ms2 Bacteriophage On The Activity And Performance Of Activated Sludge, Sean M. Stuntz
The Effect Of Ms2 Bacteriophage On The Activity And Performance Of Activated Sludge, Sean M. Stuntz
Theses and Dissertations
As a medical waste product, the MS2 bacteriophage has been discharged into wastewater distribution and treatment networks. To categorize its impact to suspended growth treatment methods, this research investigated the effect of the MS2 bacteriophage on activated sludge through a series of respirometry tests. The effects of MS2 bacteriophage at a concentration of 3.2x108 PFU/mL were assessed by determining peak O2 consumption, cumulative O2 consumption, molar CO2/O2 ratios, and shape factors. None of the MS2 samples caused statistically significant effects on the peak or cumulative O2 consumption. The molar CO2/O2 …
Influencing Effective Electrical Distribution Modernization Through Advanced Metering, Jared R. Erickson
Influencing Effective Electrical Distribution Modernization Through Advanced Metering, Jared R. Erickson
Theses and Dissertations
In 2013, the Department of Defense (DoD) required its services to implement advanced metering for the purpose of reducing energy usage (Department of Defense, 2013). Additionally, the DoD has aimed to improve its ability to assure a continuous energy supply to all of its installations. This study investigated processes for applying advanced meters on Air Force bases to increase energy assurance. This study also identified strategies for using advanced meters to influence infrastructure funding. This was accomplished through the use of extensive advanced meter data. The data was analyzed for outages and a procedure was created to locate outages in …
Occupational Noise Dose Reduction Via Behavior Modification Using In-Ear Dosimetry Among Usaf Personnel Exposed To Continuous Impulse Noise, Jesse A. Trawick
Occupational Noise Dose Reduction Via Behavior Modification Using In-Ear Dosimetry Among Usaf Personnel Exposed To Continuous Impulse Noise, Jesse A. Trawick
Theses and Dissertations
The purpose of this research was to investigate the use of in-ear noise dosimetry and worker feedback to reduce noise exposures among combat arms instructors and heavy equipment operators in the Air Force. Specifically, this thesis sought to determine how effectively hearing protection devices (HPDs) are being utilized currently, and whether providing at-ear noise exposure data to workers results in reduced noise exposures or changes in worker attitude. These questions were addressed by performing a six-month field study using dosimeters to record worker noise exposures under HPDs. Subjects served as their own control, receiving feedback in only the latter half …
Techniques For Low-Latency In Software-Defined Radio-Based Networks, Daniel D. Hart
Techniques For Low-Latency In Software-Defined Radio-Based Networks, Daniel D. Hart
Theses and Dissertations
Decreased budgets have pushed the United States Air Force towards using existing systems in new ways. The use of unmanned aerial vehicle swarms is one example of reuse of existing systems. One problem with the increased utilization of these swarms is the congestion of the electromagnetic spectrum. Software-defined or cognitive radios have been proposed as a basis for a potential robust communications solution. The present research aims to develop and test a genetic algorithm-based cognitive engine to begin looking at real-time engines that could be used in future swarms. Here, latency is the optimization objective of primary importance. In testing …
Analysis Of Cross-Cultural Training Provided To United States Air Force Civil Engineer Officers, And How Engineering Efforts Are Affected On Overseas Air Force Installations: A Delphi Study, Bianca E. Boney
Theses and Dissertations
U.S. military personnel perform a wide array of roles and missions at locations all over the world. As such, this research investigates and describes the current process of cultural training, its adequacy, and examines how cultural differences and collaboration efforts may impede or enhance project management and engineering efforts. This qualitative analysis is conducted through a Delphi study of U.S. Air Force officers consisting of 15 subject matter experts (SMEs) with experiences from 13 different countries. All reported to have daily to weekly interactions with locals and foreign partners due to job requirements; however, no set standard of cultural training …
Monte Carlo Simulations Of Three-Dimensional Electromagnetic Gaussian Schell-Model Sources, Milo W. Hyde Iv, Santasri Bose-Pillai, Olga Korotkova
Monte Carlo Simulations Of Three-Dimensional Electromagnetic Gaussian Schell-Model Sources, Milo W. Hyde Iv, Santasri Bose-Pillai, Olga Korotkova
Faculty Publications
This article presents a method to simulate a three-dimensional (3D) electromagnetic Gaussian-Schell model (EGSM) source with desired characteristics. Using the complex screen method, originally developed for the synthesis of two-dimensional stochastic electromagnetic fields, a set of equations is derived which relate the desired 3D source characteristics to those of the statistics of the random complex screen. From these equations and the 3D EGSM source realizability conditions, a single criterion is derived, which when satisfied guarantees both the realizability and simulatability of the desired 3D EGSM source. Lastly, a 3D EGSM source, with specified properties, is simulated; the Monte Carlo simulation …
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Copper-Doped Lithium Triborate (Lib3o5) Crystals: A Photoluminescence, Thermoluminescence, And Electron Paramagnetic Resonance Study, Brant E. Kananen, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Faculty Publications
When doped with copper ions, lithium borate materials are candidates for use in radiation dosimeters. Copper-doped lithium tetraborate (Li2B4O7) crystals have been widely studied, but little is known thus far about copper ions in lithium triborate (LiB3O5) crystals. In the present investigation, Cu+ ions (3d10) were diffused into an undoped LiB3O5 crystal at high temperature. These ions occupy both Li+ and interstitial positions in the crystal. A photoluminescence (PL) band peaking near 387 nm and a photoluminescence excitation (PLE) band peaking near 273 nm verify that a portion of these Cu+ ions are located at regular Li+ sites. After an …
Metastable Ar(1s5) Density Dependence On Pressure And Argon-Helium Mixture In A High Pressure Radio Frequency Dielectric Barrier Discharge, Daniel J. Emmons, David E. Weeks, Ben Eshel, Glen P. Perram
Metastable Ar(1s5) Density Dependence On Pressure And Argon-Helium Mixture In A High Pressure Radio Frequency Dielectric Barrier Discharge, Daniel J. Emmons, David E. Weeks, Ben Eshel, Glen P. Perram
Faculty Publications
Simulations of an α-mode radio frequency dielectric barrier discharge are performed for varying mixtures of argon and helium at pressures ranging from 200 to 500 Torr using both zero and one-dimensional models. Metastable densities are analyzed as a function of argon-helium mixture and pressure to determine the optimal conditions, maximizing metastable density for use in an optically pumped rare gas laser. Argon fractions corresponding to the peak metastable densities are found to be pressure dependent, shifting from approximately 15% Ar in He at 200 Torr to 10% at 500 Torr. A decrease in metastable density is observed as pressure …
Effects Of Edge Inclination Angles On Whispering-Gallery Modes In Printable Wedge Microdisk Lasers, Cong Chen, Lei Wan, Hengky Chandrahalim
Effects Of Edge Inclination Angles On Whispering-Gallery Modes In Printable Wedge Microdisk Lasers, Cong Chen, Lei Wan, Hengky Chandrahalim
Faculty Publications
The ink-jet technique was developed to print the wedge polymer microdisk lasers. The characterization of these lasers was implemented using a free-space optics measurement setup. It was found that disks of larger edge inclination angles have a larger free spectral range (FSR) and a lower resonance wavelength difference between the fundamental transverse electric (TE) and transverse magnetic (TM) whispering-gallery modes (WGMs). This behavior was also confirmed with simulations based on the modified Oxborrow’s model with perfectly matched layers (PMLs), which was adopted to accurately calculate the eigenfrequencies, electric field distributions, and quality parameters of modes in the axisymmetric microdisk resonators. …
Investigation Into Reynolds Number Effects On A Biomimetic Flapping Wing, Daniel K. Hope, Anthony M. Deluca, Ryan P. O'Hara
Investigation Into Reynolds Number Effects On A Biomimetic Flapping Wing, Daniel K. Hope, Anthony M. Deluca, Ryan P. O'Hara
Faculty Publications
This research investigated the behavior of a Manduca sexta inspired biomimetic wing as a function of Reynolds number by measuring the aerodynamic forces produced by varying the characteristic wing length and testing at air densities from atmospheric to near vacuum. A six degree of freedom balance was used to measure forces and moments, while high speed cameras were used to measure wing stroke angle. An in-house created graphical user interface was used to vary the voltage of the drive signal sent to the piezoelectric actuator which determined the wing stroke angle. The Air Force Institute of Technology baseline 50 mm …
Wavelet Anova Bisection Method For Identifying Simulation Model Bias, Andrew D. Atkinson, Raymond R. Hill, Joseph J. Pignatiello Jr., G. Geoffrey Vining, Edward D. White, Eric Chicken
Wavelet Anova Bisection Method For Identifying Simulation Model Bias, Andrew D. Atkinson, Raymond R. Hill, Joseph J. Pignatiello Jr., G. Geoffrey Vining, Edward D. White, Eric Chicken
Faculty Publications
High-resolution computer models can simulate complex systems and processes in order to evaluate a solution quickly and inexpensively. Many simulation models produce dynamic functional output, such as a set of time-series data generated during a process. These computer models require verification and validation (V&V) to assess the correctness of these simulations. In particular, the model validation effort evaluates if the model is an appropriate representation of the real-world system that it is meant to simulate. However, when assessing a model capable of generating functional output, it is useful to learn more than simply whether the model is valid or invalid. …
Unmasking Cost Growth Behavior: A Longitudinal Study, Cory N. D'Amico, Edward D. White, Jonathan D. Ritschel, Scott R. Kozlak
Unmasking Cost Growth Behavior: A Longitudinal Study, Cory N. D'Amico, Edward D. White, Jonathan D. Ritschel, Scott R. Kozlak
Faculty Publications
This article examines how cost growth factors (CGF) change over a program’s acquisition life cycle for 36 Department of Defense aircraft programs. Starting from Milestone B, the authors examine CGFs at five gateways: Critical Design Review, First Flight (FF), the end of Developmental Test and Evaluation (DT&E), Initial Operational Capability, and Full Operational Capability. Each CGF is assigned a color rating based upon the program’s cost growth: Green (low), Amber (moderate), or Red (high). Significant findings include dependencies among similar CGF color ratings and cost growth occurring primarily between FF and the end of DT&E during a program’s life cycle.
Evaluating Smartphones For Infrastructure Work Order Management, Victor L. Guinn, Brent T. Langhals, John J. Elshaw
Evaluating Smartphones For Infrastructure Work Order Management, Victor L. Guinn, Brent T. Langhals, John J. Elshaw
Faculty Publications
Infrastructure managers require timely and accurate state information to diagnose, prioritize, and repair the substantial infrastructure assets supporting modern society. Challenges in obtaining sufficient information can often be attributed to inadequate data collection procedures (phone calls, paper reports, etc.) or a general lack of knowledge or ability on the part of the reporting individual to accurately convey what is actually wrong with the facility. Fortunately, modern smart-phone technology offers the potential to improve maintenance work requests by providing better geolocation and problem description accuracy. An experiment simulating real-world maintenance requests was conducted comparing smart-phones with traditional verbal work order request …
Transferable Multiparty Computation, Michael R. Clark, Kenneth M. Hopkinson
Transferable Multiparty Computation, Michael R. Clark, Kenneth M. Hopkinson
AFIT Patents
A method and apparatus are provided for secure multiparty computation. A set of first parties is selected from a plurality of first parties for computation. Inputs for computation associated with each party in the set of first parties are divided into shares to be sent to other parties in the set of first parties. The computation on the shares is performed by the set of first parties using multiparty computation functions. In response to a trigger event, shares of the set of first parties are transferred to a set of second parties selected from a plurality of second parties. The …
Load Planning Processes To Enhance Cargo Compartment Utilization, Nathan J. Carlson, Adam D. Reiman, Robert E. Overstreet, Matthew A. Douglas
Load Planning Processes To Enhance Cargo Compartment Utilization, Nathan J. Carlson, Adam D. Reiman, Robert E. Overstreet, Matthew A. Douglas
Faculty Publications
Purpose: The United States Air Force often provides effective airlift for cargo distribution, but is at times inefficient. This paper aims to address the under-utilization of military airlift cargo compartments that plagues the airlift system.
Design/methodology/approach: The authors examine seven techniques designed to increase cargo compartment utilization and increase airlift utilization rates. The techniques were applied through load planning software to 30 real-world movements consisting of 159 sorties. They then ran each post-technique movement through a modeled flight environment to obtain cycle movement data. The metrics gained from both the load planning software and the modeled environment were regressed to …
Use Of A Novel Infrared Wavelength-Tunable Laser Mueller-Matrix Polarimetric Scatterometer To Measure Nanostructured Optical Materials, Jason C. Vap, Stephen E. Nauyoks, Michael R. Benson, Michael A. Marciniak
Use Of A Novel Infrared Wavelength-Tunable Laser Mueller-Matrix Polarimetric Scatterometer To Measure Nanostructured Optical Materials, Jason C. Vap, Stephen E. Nauyoks, Michael R. Benson, Michael A. Marciniak
Faculty Publications
Nanostructured optical materials, for example, metamaterials, have unique spectral, directional, and polarimetric properties. Samples designed and fabricated for infrared (IR) wavelengths have been characterized using broadband instruments to measure specular polarimetric transmittance or reflectance as in ellipsometry or integrated hemisphere transmittance or reflectance. We have developed a wavelength-tunable IR Mueller-matrix (Mm) polarimetric scatterometer which uses tunable external-cavity quantum-cascade lasers (EC-QCLs) to tune onto and off of the narrowband spectral resonances of nanostructured optical materials and performed full polarimeteric and directional evaluation to more fully characterize their behavior. Using a series of EC-QCLs, the instrument is tunable over 4.37-6.54 μm wavelengths …
Characterization And Scaling Study Of Energy Pathways In Small Four-Stroke Internal Combustion Engines, Jason R. Blantin
Characterization And Scaling Study Of Energy Pathways In Small Four-Stroke Internal Combustion Engines, Jason R. Blantin
Theses and Dissertations
A study of the efficiency and energy losses of a selection of five small (40 - 200 cm3 displacement) single cylinder, four-stroke engines was accomplished. The study was performed as part of a larger effort to improve the range and endurance of small internal combustion engines (ICE) that power Group II Unmanned Aerial Vehicles (UAVs). Little is known about the performance, efficiency, and allocation of energy losses for four-stroke ICEs in this size range. The goal of the study was to characterize these parameters for use in future research efforts. Three research objectives were developed to guide the study …
Engineered Surfaces To Control Secondary Electron Yield For Multipactor Suppression, James M. Sattler
Engineered Surfaces To Control Secondary Electron Yield For Multipactor Suppression, James M. Sattler
Theses and Dissertations
A significant problem for satellites, vacuum electron devices, and particle accelerators is multipactor: an avalanche of electrons caused by recurring secondary electron emission (SEE) in a time-varying electric field. The consequences of multipactor range from temporary to permanent device failure. This research studied how surface topography can be engineered to minimize SEE and suppress multipactor. Two new semi-empirical models (one based on a 2D pore, the other based on a 3D pore) were developed to predict the secondary electron yield (SEY) of a porous surface based on pore aspect ratio and porosity. The models were validated with experimental SEY measurements …
Effect Of Fused Filament Fabrication Process Parameters On The Mechanical Properties Of Carbon Fiber Reinforced Polymers, Abdulrahman S. Alwabel
Effect Of Fused Filament Fabrication Process Parameters On The Mechanical Properties Of Carbon Fiber Reinforced Polymers, Abdulrahman S. Alwabel
Theses and Dissertations
Carbon fiber reinforced polymer manufactured using additive manufacturing process is relatively a new process. The ability to predict the mechanical properties of these parts with high confidence will spread the use of these high-strength materials in more applications. The purpose of this research was to determine the effect of the build time between successive layers, arrangement of fiber and nylon layers, fiber start location, and the use of support material on the mechanical properties CFRP produced by additive manufacturing process using the MarkForged (MarkOne) 3D printer. A design of experiment (DOE) we preformed to develop a mathematical model describing the …