Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Operations Research, Systems Engineering and Industrial Engineering (28)
- Aerospace Engineering (22)
- Computer Engineering (9)
- Electrical and Computer Engineering (9)
- Operational Research (9)
-
- Civil and Environmental Engineering (8)
- Physical Sciences and Mathematics (8)
- Computer Sciences (6)
- Systems Engineering (6)
- Astrodynamics (5)
- Digital Communications and Networking (5)
- Information Security (5)
- Space Vehicles (5)
- Systems and Communications (5)
- Environmental Engineering (4)
- Construction Engineering and Management (3)
- Materials Science and Engineering (3)
- Navigation, Guidance, Control and Dynamics (3)
- Other Operations Research, Systems Engineering and Industrial Engineering (3)
- Aerodynamics and Fluid Mechanics (2)
- Business (2)
- Computer and Systems Architecture (2)
- Environmental Sciences (2)
- Industrial Technology (2)
- Medicine and Health Sciences (2)
- Occupational Health and Industrial Hygiene (2)
- Public Health (2)
- Signal Processing (2)
- Structures and Materials (2)
- Keyword
-
- #antcenter (8)
- Industrial control systems (3)
- Hypersonic vehicles (2)
- 3D printing (1)
- Absolute Position (1)
-
- Additive manufacturing (1)
- Admission control (1)
- Advanced oxidation processes (1)
- Air pollution (1)
- Aircraft availability (1)
- Amplitude scintillation (1)
- Atmospheric fluctuations (1)
- Attrition (1)
- Automated Aerial Refueling (1)
- Bipartite matching (1)
- Blended retirement system (1)
- CRM (Collision Radiative Model) (1)
- Carbon fiber reinforced plastic (1)
- Ceramic materials (1)
- Clutter models (1)
- Cold regions (1)
- Computational fluid dynamics (CFD) (1)
- Cost sharing (1)
- Crack propagation (1)
- CubeSat geolocation (1)
- Cyber defense training (1)
- Cyber first responders (1)
- Cyber incident response (1)
- Cyber security (1)
- Cyber threat (1)
Articles 1 - 30 of 73
Full-Text Articles in Engineering
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 …
Characterization Of Jet Fuel Combustion Emissions During A C-130 Aeromedical Evacuation Engines Running Onload, Michelle L. Page
Characterization Of Jet Fuel Combustion Emissions During A C-130 Aeromedical Evacuation Engines Running Onload, Michelle L. Page
Theses and Dissertations
The purpose of this research was to characterize jet fuel combustion emissions (JFCE) in an occupational setting. Prior research demonstrated that aircraft emit hazardous species, especially at engine start-up and ground idle. Complaints of eye, nose, and throat irritation from occupational exposures near aircraft exist. In this study JFCE were tested during an aeromedical evacuation engines running patient onload (ERO) on a C-130 Hercules at the 179th Airlift Wing, Mansfield-Lahm Air National Guard. Ultrafine particles, VOC, formaldehyde, carbon monoxide (CO), sulfuric acid, and metals were sampled simultaneously in approximate crew and patient breathing zones. Testing methods were portable condensation …
A Location-Aware Middleware Framework For Collaborative Visual Information Discovery And Retrieval, Andrew J.M. Compton
A Location-Aware Middleware Framework For Collaborative Visual Information Discovery And Retrieval, Andrew J.M. Compton
Theses and Dissertations
This work addresses the problem of scalable location-aware distributed indexing to enable the leveraging of collaborative effort for the construction and maintenance of world-scale visual maps and models which could support numerous activities including navigation, visual localization, persistent surveillance, structure from motion, and hazard or disaster detection. Current distributed approaches to mapping and modeling fail to incorporate global geospatial addressing and are limited in their functionality to customize search. Our solution is a peer-to-peer middleware framework based on XOR distance routing which employs a Hilbert Space curve addressing scheme in a novel distributed geographic index. This allows for a universal …
Dynamics Of Chemical Degradation In Water Using Photocatalytic Reactions In An Ultraviolet Light Emitting Diode Reactor, John E. Stubbs
Dynamics Of Chemical Degradation In Water Using Photocatalytic Reactions In An Ultraviolet Light Emitting Diode Reactor, John E. Stubbs
Theses and Dissertations
This work examined ultraviolet (UV) light emitting diodes (LED) and hydrogen peroxide in an advanced oxidation process in support of a USAF installation net zero water initiative. A UV LED reactor was used for degradation of soluble organic chemicals. There were linear relationships between input drive current, optical output power, and first order degradation rate constants. When drive current was varied, first order degradation rates depended on chemical identities and the drive current. When molar peroxide ratios were varied, kinetic profiles revealed peroxide-limited or radical-scavenged phenomena. Molar absorptivity helped explain the complexity of chemical removal profiles. Degradation kinetics were used …
Evaluating Process Improvement Courses Of Action Through Modeling And Simulation, Joseph R. Owens
Evaluating Process Improvement Courses Of Action Through Modeling And Simulation, Joseph R. Owens
Theses and Dissertations
Quantifying an expected improvement when considering moderate-complexity changes to a process is time consuming and has potential to overlook stochastic effects. By modeling a process as a Numerical Design Structure Matrix (NDSM), simulating the proposed changes, and evaluating performance, quantification can be rapidly accomplished to understand stochastic effects. This thesis explores a method to evaluate complex process changes within Six Sigma DMAIC process improvement to identify the most desirable outcome amongst several improvement options. A tool to perform the modeling and evaluation is developed. This process evaluation tool is verified for functionality, then is demonstrated against generic processes, a case …
Satellite Propulsion Spectral Signature Detection And Analysis For Space Situational Awareness Using Small Telescopes, Pamela L. Wheeler
Satellite Propulsion Spectral Signature Detection And Analysis For Space Situational Awareness Using Small Telescopes, Pamela L. Wheeler
Theses and Dissertations
Safe satellite operations are of utmost importance. Maintaining precise orbital maintenance places stringent performance requirements on current propulsion systems, which are often electric propulsion systems. Electron temperature is a commonly used diagnostic to determine the performance of a Hall thruster, and recent work has correlated near infrared (NIR) spectral measurements of ionization lines of xenon and krypton to electron temperature measurements. In the research herein, appropriate line spectra ratios are identified for each propellant type when used with remote space-to-ground observations. NIR plume emissions were used to characterize a 600 Watt Hall thruster for a variety of observation angles and …
Optimal Control Methods For Missile Evasion, Ryan W. Carr
Optimal Control Methods For Missile Evasion, Ryan W. Carr
Theses and Dissertations
Optimal control theory is applied to the study of missile evasion, particularly in the case of a single pursuing missile versus a single evading aircraft. It is proposed to divide the evasion problem into two phases, where the primary considerations are energy and maneuverability, respectively. Traditional evasion tactics are well documented for use in the maneuverability phase. To represent the first phase dominated by energy management, the optimal control problem may be posed in two ways, as a fixed final time problem with the objective of maximizing the final distance between the evader and pursuer, and as a free final …
Analysis Of An Experimental Space Debris Removal Mission, Krista L.L. Roth
Analysis Of An Experimental Space Debris Removal Mission, Krista L.L. Roth
Theses and Dissertations
Encountering space debris is an ever-increasing problem in space exploration and exploitation, especially in Low Earth Orbit. While many space-faring governing bodies have attempted to control the orbital lifetime post mission completion of satellites and rocker bodies, objects already in orbit pose a danger to future mission planning. Currently, governments and academic institutions are working to develop missions to remove space debris; however, the proposed missions are typically costly primary missions. This research proposes an alternative to use an upper stage rocket, to be called a chaser, already launching a primary mission near the desired debris as a host for …
Analyzing The Critical Supply Chain For Unmanned Aircraft Systems, Megan L. Muniz
Analyzing The Critical Supply Chain For Unmanned Aircraft Systems, Megan L. Muniz
Theses and Dissertations
Unmanned aerial systems (UAS) play a vital role in present day operations due their asset capability and ability to reduce risk to pilots’ lives. A complex supply chain network capable of producing and integrating all raw materials, components, sub- systems, and systems supports the successful acquisition of a UAS. Such a complex network is supported by vital supply chain decisions. Two important decisions regarding supply chain design include supplier selection and optimal flow of material and product Whether a decision maker wishes to design or interdict a supply chain, the methodology developed in this thesis provides a suite of tailorable …
Feasibility And Environmental Implications Of Using Waste Motor Oil As Alternative Supplemental Fuel In Contingency Prime Power Generation, Zachary S. Bierhaus
Feasibility And Environmental Implications Of Using Waste Motor Oil As Alternative Supplemental Fuel In Contingency Prime Power Generation, Zachary S. Bierhaus
Theses and Dissertations
In an era of strict hazardous material restrictions and intense energy savings projects, DoD has an opportunity for a waste-to-energy initiative by looking to vintage diesel engine technology for inspiration. The idea comes in the form of recycled Waste Motor Oil (WMO) which can be used as a fuel in compression-ignition engines. When mixed at a low blend ratio, WMO can supplement diesel fuels to extend the range of fuel stores for electrical power generating equipment at contingency military bases while simultaneously decreasing the burden on fuel supply chain management and the hazardous waste disposal stream. This research looked at …
A Portfolio Decision Analysis Study For Improving Consequence Of Facility Failure Indices, Michael J. Blaess
A Portfolio Decision Analysis Study For Improving Consequence Of Facility Failure Indices, Michael J. Blaess
Theses and Dissertations
The United States Air Force partially integrated the Mission Dependency Index (MDI) into its portfolio project selection model by assigning an MDI value to a facility type or real property category code (CATCODE) in lieu of assigning a unique MDI value to each facility through a structured interview process. This took an initial step to improve the Air Forces asset management practices; however, it failed to accurately capture the consequence of facility failure in some cases. Although a process to adjudicate the MDI value of individual facilities was created, it is still unknown how much the surveyed MDI value deviates …
Relating Film Cooling Performance Between Ambient And Near Engine Temperatures, Christopher J. Vorgert
Relating Film Cooling Performance Between Ambient And Near Engine Temperatures, Christopher J. Vorgert
Theses and Dissertations
This thesis explores multiple topics, including the relative importance of nondimensional parameters that relate film cooling performance within different temperature regimes and the effects of internal coolant flow and coolant temperature on overall film cooling effectiveness. A Hastelloy model representative of a turbine blade was utilized for IR tests. Near engine temperatures were produced via premixed propane and air combustion in a Well-Stirred Reactor (WSR) with air supplied as the film coolant gas. Near ambient conditions used heated air for freestream flow and carbon dioxide, argon, or air as film coolant gases. It was found that even with multiple matched …
Applying Cyber Threat Intelligence To Industrial Control Systems, Matthew P. Sibiga
Applying Cyber Threat Intelligence To Industrial Control Systems, Matthew P. Sibiga
Theses and Dissertations
A cybersecurity initiative known as cyber threat intelligence (CTI) has recently been developed and deployed. The overall goal of this new technology is to help protect network infrastructures. Threat intelligence platforms (TIPs) have also been created to help facilitate CTI effectiveness within organizations. There are many benefits that both can achieve within the information technology (IT) sector. The industrial control system (ICS) sector can also benefit from these technologies as most ICS networks are connected to IT networks. CTI and TIPs become resourceful when using indicators of compromise (IOCs) from known ICS malware attacks and an open source intrusion detection …
A Scenario-Based Parametric Analysis Of Stable Marriage Approaches To The Army Officer Assignment Problem, Matthew D. Ferguson
A Scenario-Based Parametric Analysis Of Stable Marriage Approaches To The Army Officer Assignment Problem, Matthew D. Ferguson
Theses and Dissertations
This paper compares linear programming and stable marriage approaches to the assignment problem under conditions of uncertainty. Robust solutions should exhibit reduced variability in the presence of one or more additional constraints. Several variations of each approach are compared with respect to solution quality, as measured by the overall social welfare among Officers and Assignments, and robustness as measured by the number of changes after a number of randomized perturbations. We examine the contrasts between these methods in the context of assigning Army Officers among a set of identified assignments. Additional constraints are modeled after realistic scenarios faced by Army …
Survival Analysis Of Us Air Force Officer Retention Rate, Courtney N. Franzen
Survival Analysis Of Us Air Force Officer Retention Rate, Courtney N. Franzen
Theses and Dissertations
Personnel retention is a matter of great interest in the private and public sectors. In the public sector--specifically the US Air Force--maintaining appropriate retention levels of rated officers is paramount as these officers are the backbone of the Air Force’s mission. As part of the effort to ensure proper retention rates for rated officers, retention models are created by the Air Force Personnel division that assist in predicting future retention patterns and accession needs. The techniques for creating these models, known as the "sustainment line," involve utilizing average retention percentages obtained from historical data. In this study, more statistical-based methods …
Reliability And Cost Impacts For Attritable Systems, Bryan R. Bentz
Reliability And Cost Impacts For Attritable Systems, Bryan R. Bentz
Theses and Dissertations
Attritable systems trade system attributes like reliability and reparability to achieve lower acquisition cost and decrease cost risk. Ultimately, it is hoped that by trading these attributes the amount of systems able to be acquired will be increased. However, the effect of trading these attributes on system-level reliability and cost risk is difficult to express complicated reparable systems like an air vehicle. Failure-time and cost data from a baseline limited-life air vehicle is analyzed for this reliability and reparability trade study. The appropriateness of various reliability and cost estimation techniques are examined for these data. This research employs the cumulative …
Optimal Configurations For Aerosol Monitoring With Multi-Rotor Small Unmanned Aerial Systems, Inna D. Chavez
Optimal Configurations For Aerosol Monitoring With Multi-Rotor Small Unmanned Aerial Systems, Inna D. Chavez
Theses and Dissertations
Applicability of aerosol sampling on multi-rotor unmanned aerial systems (UAS) platform was investigated. Multi-rotor UAS have impacts of wind speed, turbulence, and orientation possibly contributing to sampling bias. The SKC IMPACT sampler, Tecora C.A.Th.I.A., and modified three-dimensionally printed Universal Inlet for Airborne-Particle Size-Selective Sampling were selected based on particle size-selectivity and operational independence to wind. Airflow visualizations concluded that below UAS fuselage was optimal sampler placement. Tests were conducted with Arizona Road Dust in a still-air chamber, and aerosolized sugar in a wind tunnel. Inlet mounting was evaluated in, upright, upside-down, and horizontal orientations. Horizontal orientations of all inlets resulted …
The Impacts Of Climate Change And Anthropogenic Processes On Permafrost Soils And Usaf Infrastructure Within Northern Tier Bases, Alexander J. Graboski
The Impacts Of Climate Change And Anthropogenic Processes On Permafrost Soils And Usaf Infrastructure Within Northern Tier Bases, Alexander J. Graboski
Theses and Dissertations
The Department of Defense is planning over $552M in military construction on Eielson Air Force Base within the next three fiscal years. Although many studies have been conducted on permafrost and climate change, the future of our climate as well as any impacts on permafrost soils, remains unclear. This research focused on future climate predictions to determine likely scenarios for the United States Air Force’s Strategic Planners to consider. The most recent 2013 International Panel on Climate Change report predicts a 2.2ºC to 7.8ºC temperature rise in Arctic regions by the end of the 21st Century in the Representative Concentration …
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 900°C In Air And In Silicic Acid-Saturated Steam, Ronald K. Mitchell
Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 900°C In Air And In Silicic Acid-Saturated Steam, Ronald K. Mitchell
Theses and Dissertations
Advanced SiC/SiC ceramic matrix composites (CMCs) are being considered for demanding aerospace applications such as aircraft engine hot-section components. In these applications the composites will be subjected to cyclic and sustained loadings at elevated temperature in aggressive combustion environments. Current aircraft engines employ Nickel-based superalloys in applications such turbine blades, where the metallic alloys must perform at or near their operating temperature limits in highly corrosive environments. The SiC/SiC composites, which offer low density, high strength and fracture toughness at elevated temperatures could potentially replace Nickel-based superalloy in aircraft engine applications. However, before the SiC/SiC composites can be safely used …
Real-Time Heuristic Algorithms For The Static Weapon-Target Assignment Problem, Alexander G. Kline
Real-Time Heuristic Algorithms For The Static Weapon-Target Assignment Problem, Alexander G. Kline
Theses and Dissertations
The problem of targeting and engaging individual missiles (targets) with an arsenal of interceptors (weapons) is known as the weapon target assignment problem. As many solution techniques are based upon a transformation of the objective function, their final solutions rarely produce optimal solutions. We propose a nonlinear branch and bound algorithm to provide the first optimization approach to the untransformed problem found in the literature. Further, we propose a new heuristic based upon the branch and bound algorithm which dominates other heuristics explored in optimality gap. We also propose a heuristic based upon the optimal solution to the quiz problem …
Formation Flight Of Earth Satellites On Kam Torus Using Classical Orbital Elements, Marissa C. Reabe
Formation Flight Of Earth Satellites On Kam Torus Using Classical Orbital Elements, Marissa C. Reabe
Theses and Dissertations
This research uses the KAM theory that has been refined by Wiesel to show that Earth-satellites dynamics can be represented by an integrable Hamiltonian system with a small perturbation, like Earths geopotential. The satellite will follow a torus in phase space and remain on that KAM torus for all time unless acted on by a non-conservative force. A torus frequency was calculated, in this research, using a truth model in System Tool Kit (STK) and the High Precision Orbit Propagator (HPOP) to develop an accurate ephemeris file listing the Classical Orbital Elements (COEs). The frequencies found from the truth model …
Investigating Analytical And Numerical Methods To Predict Satellite Orbits Using Two-Line Element Sets, Adam T. Rich
Investigating Analytical And Numerical Methods To Predict Satellite Orbits Using Two-Line Element Sets, Adam T. Rich
Theses and Dissertations
As Low Earth Orbit (LEO) contains an ever-increasing number of objects, the prediction of future object positions must be precise in order to avoid collisions. Object positions are distributed in two-line element (TLE) sets and are generated using the analytical propagator known as Simplified General Perturbations 4 (SGP4). However, a numerical integrator called Special Perturbations (SP) provides an alternative approach to TLE generation and propagation. In this thesis, TLE accuracy was determined with both models, and the length of time that a single element set can provide valid information was also established. With two-line element sets as data, comparisons were …
United States Air Force Unaccompanied Housing Divestiture: An Economic Analysis, Dustin L. Gooden
United States Air Force Unaccompanied Housing Divestiture: An Economic Analysis, Dustin L. Gooden
Theses and Dissertations
The objective of this research is to determine potential cost savings associated with Air Force unaccompanied housing divestiture. This research uses Air Education and Training Command (AETC) installations as the data sample for the analysis, and will analyze the status quo, privatization, and identical FSRM options. With 16% of Air Force unaccompanied housing currently rated at various levels of inadequacy and the PRV for the inadequate housing at $2,315,773,149.00, the costs associated with renovating the inadequate unaccompanied housing is substantial. Moreover, the inadequacy of unaccompanied housing is part of the Air Force’s acceptance of risk in facilities and infrastructure to …
An Investigation Into The Indicators Of A Successful Total Force Association, Greg E. Hoyt
An Investigation Into The Indicators Of A Successful Total Force Association, Greg E. Hoyt
Theses and Dissertations
The Air Force, since adopting and subsequently developing the Total Force concept in the early 1970s, has not thoroughly outlined clear objectives by which the progress toward and realization of this strategic vision should be defined and measured. Without clear definition, direction, and method of evaluation, the ability to credibly claim any subsequent successes or failures in the pursuit of this vision become vulnerable to challenge. Indeed, the mere claim that a single, clear vision exists may be challenged. The Total Force concepts degree of success has, on multiple occasions through its history, been critiqued with the most recent instance …
Transient Nonlinear Optical Properties Of Thin Film Titanium Nitride, Sarahkatie Thomas
Transient Nonlinear Optical Properties Of Thin Film Titanium Nitride, Sarahkatie Thomas
Theses and Dissertations
nitride (TiN) and scandium nitride (ScN), using the beam deflection characterization technique. The thin films were made at the Air Force Research Lab by controllably unbalanced magnetron sputtering. Transition metal nitrides, specifically TiN, are used widely in industry because of their unique properties, including extreme hardness and high damage threshold. The properties of thin film transition metal nitrites are dependent on the chemical structure of the thin film, which can be heavily influenced by substrate and deposition method. This durability and tunability is an asset in applications such as sensor protection and all optical computing. Two substrates, sapphire (Al2 …
On Proportionate And Truthful International Alliance Contributions: An Analysis Of Incentive Compatible Cost Sharing Mechanisms To Burden Sharing, William N. Caballero
On Proportionate And Truthful International Alliance Contributions: An Analysis Of Incentive Compatible Cost Sharing Mechanisms To Burden Sharing, William N. Caballero
Theses and Dissertations
Burden sharing within an international alliance is a contentious topic, especially in the current geopolitical environment, that in practice is generally imposed by a central authority's perception of its members' abilities to contribute. Instead, we propose a cost sharing mechanism such that burden shares are allocated to nations based on their honest declarations of the alliance's worth. Specifically, we develop a set of multiobjective nonlinear optimization problem formulations that respectively impose Bayesian Incentive Compatible (BIC), Strategyproof (SP), and Group Strategyproof (GSP) mechanisms based on probabilistic inspection efforts and deception penalties that are budget balanced and in the core. Any feasible …
Optimal Design Of A Hexakis Icosahedron Vacuum Based Lighter Than Air Vehicle, Joseph R. Schwemmer
Optimal Design Of A Hexakis Icosahedron Vacuum Based Lighter Than Air Vehicle, Joseph R. Schwemmer
Theses and Dissertations
Due to the rising cost and scarcity of helium, new methods to ensure buoyancy for lighter-than-air vehicles (LTAVs) are being sought. One alternative under study uses an internal vacuum to reduce the weight to buoyancy ratio. It's a novel approach; however, the vacuum presents challenges for the vehicle's structure. The structure must have minimum mass while preventing buckling and excess stress throughout the frame and membrane. The structure under analysis is a hexakis icosahedron with a membrane covering. Achieving minimum mass involves optimizing the structure under the loading conditions. Finite-element analysis (FEA) and direct-search methods are employed, providing an optimal …
Application Of Enlisted Force Retention Levels And Career Field Stability, Jamie T. Zimmermann
Application Of Enlisted Force Retention Levels And Career Field Stability, Jamie T. Zimmermann
Theses and Dissertations
The Air Force’s success is influenced by the manpower it has. The end-strength is Congressionally mandated. Predicting personnel retention is critical to the operations of the military. Over 10 years ago, the Air Force produced enlisted career field sustainment lines based on manning. If a career field was over manned the authorizations were decreased, likewise if a career field was under manned the authorizations were increased. The constant fluctuation of manning caused bathtubs to be created and requirements to go unfilled. Currently, the Air Force produces enlisted career field sustainment lines based on the 5-year historical retention rates. This method …