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Full-Text Articles in Engineering

Empirical Evaluation Of The Civil Engineer Career Pyramid And Career Guidance, Travis K. Leighton Mar 2000

Empirical Evaluation Of The Civil Engineer Career Pyramid And Career Guidance, Travis K. Leighton

Theses and Dissertations

Air Force civil engineer officers rely on published guidance to assist in establishing their career objectives. This thesis uses empirical data to evaluate the published Air Force career guidance. The data set is comprised of complete duty histories from all active duty lieutenant colonels in the civil engineer career field. The guidance implies a career path to become a civil engineer squadron commander but provides no empirical validation. This thesis follows a rigorous procedure to objectively evaluate the Air Force guidance. The guidance is translated into 24 research questions based on its main tenets. Each duty occurrence is categorized by …


An Intelligent User Interface To Support Air Force Weather Product Generation And Automated Metrics, Darryl N. Leon Mar 2000

An Intelligent User Interface To Support Air Force Weather Product Generation And Automated Metrics, Darryl N. Leon

Theses and Dissertations

Air Force pilots require dependable weather reports so they may avoid unsafe flying conditions. In order to better gauge the accuracy of its weather products, Air Force Weather has established the requirement for an Air Force-wide automated weather metrics program. Under the guidelines for this program, forecasts will automatically be compared to observed weather to determine their accuracy. Statistics will be collected in the hopes of determining forecast error trends that can be corrected through education and training. In order for the statistical data produced by such a program to draw reliable conclusions about forecast accuracy, however, the correct format …


Optical Investigation Of Molecular Beam Epitaxy AlXGa1-XN To Determine Material Quality, Judith L. Mcfall Mar 2000

Optical Investigation Of Molecular Beam Epitaxy AlXGa1-XN To Determine Material Quality, Judith L. Mcfall

Theses and Dissertations

The purpose of this research was to determine the quality of AIGaN samples with various mole fractions of aluminum doped with silicon. The samples utilized for this study were composed of an AIN buffer layer sandwiched between the sapphire substrate and AIGaN epilayer grown by molecular beam epitaxy (MBE). Cathodoluminescence (CL) and photoluminescence (PL) were employed to determine the mole fraction of aluminum in each sample. These techniques also gave insight into the material's nonuniformity, defects, and impurities. CL was run at 4 different beam energies (2,5,10, & 15 keV) with four different currents (1,10,50, & 90 µA) for the …


Investigation Into The Adaptation Of A Steam Injector For Use On A Liquid Rocket Engine, Charles B. Mcfarland Mar 2000

Investigation Into The Adaptation Of A Steam Injector For Use On A Liquid Rocket Engine, Charles B. Mcfarland

Theses and Dissertations

This thesis investigated the properties of a steam injector to see if the concept might be suitable for use on a liquid rocket engine. A steam injector is a device developed in the 1850's to inject feedwater into the boiler on a steam locomotive without any moving parts. The injectors uses a small portion of the steam generated in the boiler to increase the pressure of the feedwater to a level high than the pressure in the boiler. Previous experiments claim that condensation of steam to water was necessary for an injector to work. This experiment tested injection without condensation …


Mechanics Of A Functionally-Graded Titanium Matrix Composite, G. Brandt Miller Mar 2000

Mechanics Of A Functionally-Graded Titanium Matrix Composite, G. Brandt Miller

Theses and Dissertations

Functionally-graded Titanium Matrix Composites, (F/G TMCs) combine the ideal properties of titanium matrix composites with the more practical machining qualities of monolithic (unreinforced) alloy. This material shows great promise in application to aerospace structural components - even in parts whose design requirements have defied the use of composite materials in the past. Successful implementation of such a material would lead to enhanced aircraft performance. However, the basic properties of a functionally-graded titanium matrix composite need to be investigated. The composite/alloy transition region, or joint area, may be less strong than its constituents and therefore determine the overall performance of the …


Leontief Metamodeling For Military Strategic Effects, Anthony W. Snodgrass Mar 2000

Leontief Metamodeling For Military Strategic Effects, Anthony W. Snodgrass

Theses and Dissertations

In this research, we propose and demonstrate an approach to incorporate currently un-modeled interactions into an existing or a new combat model or simulation. We apply the Leontief Input-Output model, which is a macro-economic model that measures the interactions between major industrial sectors of an economy, as a metamodel that periodically assesses the status of various combat units and support functions. If needed resources are insufficient, appropriate degrades are input into the combat model. As a result, dependencies that are not in the combat model are incorporated. Hence, we can assess the strategic or cascading effects of destroying a set …


The Air Force Institute Of Technology (Afit) Micro Electro-Mechanical Systems (Mems) Interferometric Gyroscope (Mig), Jeremy P. Stringer Mar 2000

The Air Force Institute Of Technology (Afit) Micro Electro-Mechanical Systems (Mems) Interferometric Gyroscope (Mig), Jeremy P. Stringer

Theses and Dissertations

With the invention of Micro Electro-Mechanical Systems (MEMS) it has become possible to fabricate micro-inertial sensors. These new sensors have application in creating autonomous guided weapons systems. New technologies like Micro Unmanned Aerial Vehicles (UAVs), which cannot use conventional inertial sensors, rely on technologies like micro-inertial sensors to operate. Also, such sensors have the capability to reduce both power and space consumption on conventional aircraft. This technology is not yet mature, and current micro-inertial sensors do not have the accuracy required for highly precise navigation. To try to increase the accuracy of micro-inertial sensors, researchers are turning toward micro-optical gyroscopes. …


A Greedy Multiple-Knapsack Heuristic For Solving Air Mobility Command’S Intratheater Airlift Problem, Nicholas J. Zeisler Mar 2000

A Greedy Multiple-Knapsack Heuristic For Solving Air Mobility Command’S Intratheater Airlift Problem, Nicholas J. Zeisler

Theses and Dissertations

This research develops a methodology using a greedy heuristic to solve Air Mobility Command's intratheater airlift scenario as a multiple knapsack problem. The objective is to maximize throughput in a theater given a vehicle mixture and assignment scheme. The model allows for a heterogeneous, user defined vehicle mix in a theater consisting of up to five bed down locations and up to seven forward operating locations. First, we preprocess routes, eliminating the large number of unattractive route choices in the problem. Then using a greedy heuristic, we select routes and assign them to aircraft located at any or all of …


A Performance Analysis Of A Joint Lmds/ Satellite Communication Network, Ronald J. Zwickel Mar 2000

A Performance Analysis Of A Joint Lmds/ Satellite Communication Network, Ronald J. Zwickel

Theses and Dissertations

The goal of this research is to provide a performance analysis of a joint terrestrial/ satellite communication network. The systems of interest are the Local Multipoint Distribution Service (LMDS) terrestrial system and the proposed Teledesic satellite network. This analysis is performed using the OPNET network simulation tool. Simulations are run for twelve separate scenarios involving three factors which include: number of users, modulation type, and Quality of Service (QoS). The key metrics for characterizing simulation scenarios are the end-to-end delay, bit error rate, and average system throughput. The results obtained display the benefit of improved throughput, approximately 20 Mbps for …


Simulation Evaluation Of The Combat Value Of A Standoff Precision Airdrop Capability, Michael W. Varner Mar 2000

Simulation Evaluation Of The Combat Value Of A Standoff Precision Airdrop Capability, Michael W. Varner

Theses and Dissertations

This project is a simulation evaluation of the developmental standoff precision airdrop (SOPAD) capability. SOPAD is a new technology under consideration to deliver supplies to forward-deployed units using either a semi-rigid wing or a guided parafoil. These delivery systems allow airdrop of supplies from altitudes of 25,000 feet and distances 25 miles from the delivery point. Using global positioning system guidance, on board navigational computers, and automatic steering mechanisms, the delivery system flies to the target following a designated flight plan. The concept includes delivering supplies to remote and potentially hostile areas without endangering the supply aircraft. In addition, supplies …


A Tabu Search Metaheuristic For The Air Refueling Tanker Assignment Problem, Shay R. Capehart Mar 2000

A Tabu Search Metaheuristic For The Air Refueling Tanker Assignment Problem, Shay R. Capehart

Theses and Dissertations

In a joint effort between Air Mobility Command (AMC) and the Air Force Institute of Technology, we present a Tanker Assignment Problem (TAP) Tool capable of providing tanker mission plans for deployment scenarios. Due to the complex nature of extracting a mission plan from the Combined Mating and Ranging Planning System (CMARPS), AMC requires a tool to provide similar results in a simpler and less time consuming manner. The tool developed allows AMC to input several receiver groups consisting of various aircraft types and numbers. Each receiver group contains a point of origin and destination, with the option of providing …


Network Security Versus Network Connectivity: A Framework For Addressing The Issues Facing The Air Force Medical Community, Franklin E. Cunningham Jr. Dec 1999

Network Security Versus Network Connectivity: A Framework For Addressing The Issues Facing The Air Force Medical Community, Franklin E. Cunningham Jr.

Theses and Dissertations

The Air Force has instituted Barrier Reef to protect its networks. The Air Force medical community operates network connections that are incompatible with Barrier Reef. To overcome this problem, OASD(HA) directed the Tri-Service Management Program Office (TIMPO) to develop an architecture that protects all military health systems and allows them to link with all three services and outside partners. This research studied the underlying networking issues and formed a framework based on data from network experts from the Air Force's medical centers and their base network organizations. The findings were compared TIMPO and a composite framework was developed that more …


Defining Virtual Interactions: A Taxonomy For Researchers And Practitioners, Glade G. Oxborrow Dec 1999

Defining Virtual Interactions: A Taxonomy For Researchers And Practitioners, Glade G. Oxborrow

Theses and Dissertations

Many uses for virtual technology are being identified by diverse organizational entities around the world. Before these technologies can be fully utilized, it is important to have a common definition and understanding of what is meant by the term virtual. It is also important to understand the structural configurations possible using virtual technology and the types of virtual interactions that may occur using these technologies. This thesis will define the basic premises, structures, and definitions applicable to vial interactions. It also defines various types of virtual interactions that may occur using virtual technology. These designations will help both practitioners and …


Approximation And Optimization Of An Auditory Model For Realization In Vlsi Hardware, Samuel L. Sangregory Dec 1999

Approximation And Optimization Of An Auditory Model For Realization In Vlsi Hardware, Samuel L. Sangregory

Theses and Dissertations

The Auditory Image Model (AIM) is a software tool set developed to functionally model the role of the ear in the human hearing process. AIM includes detailed filter equations for the major functional portions of the ear. Currently, AIM is run on a workstation and requires 10 to 100 times real-time to process audio information and produce an auditory image. An all-digital approximation of the AIM which is suitable for implementation in very large scale integrated circuits is presented. This document details the mathematical models of AIM and the approximations and optimizations used to simplify the filtering and signal processing …


Electrical And Optical Characterization Of Intrinsic And Ion-Implantation Induced Defects In 6h- And 4h-Sic, Michael B. Scott Dec 1999

Electrical And Optical Characterization Of Intrinsic And Ion-Implantation Induced Defects In 6h- And 4h-Sic, Michael B. Scott

Theses and Dissertations

Deep level transient spectroscopy (DLTS), Hall effect, and cathodolummescence (CL) measurements are used to characterize the intrinsic and ion-implantation induced defects in high-temperature (475 and 500 °C) ion-implanted epitaxial n-type 6H- and 4H-SiC, ion-implanted with Cr, Mg, Ar, N, and P atoms. Comparison of room-temperature and high-temperature ion-implanted 6H-SiC:Mg and :Cr indicate the significance of high-temperature ion implantation on the activation of the ion-implanted atoms and damage-recovery of the crystalline lattice. The effects of high-temperature annealing on both damage-recovery and implanted ion activation are detected and analyzed, from 1200 to 1800 °C. Trap parameters of both damage-related and species-related defects …


Power, Performance, And Perception (P3): Integrating Usability Metrics And Technology Acceptance Determinants To Validate A New Model For Predicting System Usage, Alan P. Fiorello Dec 1999

Power, Performance, And Perception (P3): Integrating Usability Metrics And Technology Acceptance Determinants To Validate A New Model For Predicting System Usage, Alan P. Fiorello

Theses and Dissertations

Currently, there are two distinct approaches to assist information technology managers in the successful implementation of office automation software. The first approach resides within the field of usability engineering, while the second approach is derived from the discipline of management information systems (MIS). However, neither approach has successfully produced conclusive evidence that explains what characteristics facilitate system use as well as influence user acceptance of the system. This study reports on the validity of a new model, entitled the Power, Performance, Perception (P3) model, that links the constructs of usability engineering to user acceptance. Additionally, speech recognition software (SRS) was …


Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii Dec 1999

Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii

Theses and Dissertations

Thin rectangular samples of Ti-6Al-4V were damaged by four methods to represent foreign object damage found in turbine engine blades: 1) impact with 2 mm and 5 mm diameter glass spheres at 305 m/s, 2) impact with 2 mm and 4 mm diameter steel spheres at 305 m/s, 3) quasi-static displacement controlled indentation using steel chisels with 1 mm, 2 mm and 5 mm diameter tips and 4) shearing notches with a 2 mm diameter chisel point under a quasi-static loading condition. Finite element analysis was used to study the relationship between the stress state created by the plastic damage …


Reverse Engineering Of Foreign Missiles Via Genetic Algorithm, Jon D. Wollam Dec 1999

Reverse Engineering Of Foreign Missiles Via Genetic Algorithm, Jon D. Wollam

Theses and Dissertations

One mission of the National Air Intelligence Center (NAIC) is the reverse engineering of foreign missile weapon systems from incomplete observational data. In the past, intuition and repeated runs of a missile performance model were required to converge to a solution compatible with observed flight characteristics. This approach can be cumbersome and time consuming, as well as being subject to undesirable influences from the analyst's preconceptions and biases. An alternative approach has been created to apply genetic algorithm (GA) techniques to allow automation of the process, wider exploration of the design space, and more optimal solutions matching the observational data. …


Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr Dec 1999

Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr

Theses and Dissertations

Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms …


Professional Contracting Certification: An Examination And Model Development, Robert D. Lorton, Daniel I. Dunn Sep 1999

Professional Contracting Certification: An Examination And Model Development, Robert D. Lorton, Daniel I. Dunn

Theses and Dissertations

This study compared the elements of existing contracting certification programs to an ideal contracting certification model developed by experts. The expert panel responded to an open-ended electronic interview to convey their ideas regarding the individual elements for the model. Input received from the initial interviews was used to develop a survey for the panel members. The surveys were completed and results were recorded and conveyed back to the panel members. This process was repeated until a majority was reached on each individual element of the model, resulting in the ideal certification model. The final model contained elements of both the …


A Methodology For The Analysis And Prediction Of Air Force Enlisted Aircraft Maintenance Personnel Retention Rates Using Economic Statistics, Peter D. Lommen Sep 1999

A Methodology For The Analysis And Prediction Of Air Force Enlisted Aircraft Maintenance Personnel Retention Rates Using Economic Statistics, Peter D. Lommen

Theses and Dissertations

The purpose of this study is to investigate the effects of certain national economic indicators on enlisted aircraft maintenance personnel retention rates. To fulfill this purpose, this study builds a linear regression equation that can predict the retention rate using the civilian unemployment rate and the index of 11 leading economic indicators as the independent variables. Journal literature and economic texts were reviewed to identify the indicators as good predictors for changes in employee turnover. The method of linear regression was used to build the model needed to predict the changes in the retention rate. The equation developed with this …


Space-Available Transportation: An Analysis Of The Cost Of Providing 'Free' Travel, Frank J. Long Sep 1999

Space-Available Transportation: An Analysis Of The Cost Of Providing 'Free' Travel, Frank J. Long

Theses and Dissertations

The purpose of this study is to estimate the costs borne by the government for providing space-available travel to eligible uniformed services personnel and their dependents. As the primary provider of the space-available privilege, it is important that the Air Force have an estimate of the burden that the administration of that privilege places on the budget. In January 1993, the Air Force discontinued its 15-year-old practice of charging a fee for space-available travel aboard AMC-owned or controlled aircraft. The fee had been set at $10 in 1978 and was collected to recover a portion of the costs associated with …


The Privatization Of The Aerospace Guidance And Metrology Center At Newark Air Force Base, Richard H. Fillman Jr. Sep 1999

The Privatization Of The Aerospace Guidance And Metrology Center At Newark Air Force Base, Richard H. Fillman Jr.

Theses and Dissertations

The Aerospace Guidance and Metrology Center (AGMC) at Newark AFB was privatized in place as a result of the 1993 BRAC process. This was a first of a kind for the DoD repair depot system. The justification was too much excess depot capacity and by closing Newark the Air Force would rid itself of this excess capacity and obtain savings by privatizing the repair workload. This thesis concentrates on whether excess capacity at AGMC was as large as it was identified and if cost saving had materialized at the depot since the privatization. To determine how well the depot repairs …


Reparable Inventory Reduction: Impacts On Air Force Fighter Aicraft Mission Capability, Gregory E. Hutson Sep 1999

Reparable Inventory Reduction: Impacts On Air Force Fighter Aicraft Mission Capability, Gregory E. Hutson

Theses and Dissertations

During the 1990's the Air Force experienced severe declines in serviceable inventory levels and a rise in their TNMCS rates. Air Force predictions of TNMCS hours during this time period did not account for the upward trend in TNMCS rates. The Air Force uses a regression equation, consisting of possessed hours, flying hours, and sorties, to predict TNMCS hours. This research, through simple linear regression, found a significant relationship between serviceable inventory levels and TNMCS rates for 8 of the 10 aircraft studied. Using this relationship, serviceable inventory levels were then added to the Air Force equations and new multiple …


Comparison Of The Effects Of Eight-Hour And Twelve-Hour Shifts On Air Force Aircraft Maintenance Production Levels, David P. Collette Sep 1999

Comparison Of The Effects Of Eight-Hour And Twelve-Hour Shifts On Air Force Aircraft Maintenance Production Levels, David P. Collette

Theses and Dissertations

his is a follow-on study that examined the effects of converting a large aircraft maintenance squadron from 8-hour shifts to 12-hour shifts. The squadron studied converted its 24-hour maintenance work force from three 8-hour work shifts to two 12-hour work shifts. Data was collected from four different time periods. Three time periods were used for a primary analysis and all four time periods were used for trend analysis. To determine if the 12-hour work shift was effective, workforce productivity was measured during the different work shift periods. Results showed an increase in two productivity measurements, no-change in two productivity measurements, …


The Effect Of Action Workouts On Aircraft Mission Capability Measurements, Michael P. Allison Sep 1999

The Effect Of Action Workouts On Aircraft Mission Capability Measurements, Michael P. Allison

Theses and Dissertations

Previous studies concerning quality improvement and the Action Workout Process attempted to define and describe the difficult concept of quality. A logical next step is to study to what extent implementation of a quality improvement program, such as ACC's Action Workout Process, positively or negatively affects performance factors within an Air Force organization. This study focused on exploring the fundamental question of whether there was, as a result of the Action Workout, a noticeable, statistically verifiable, positive or negative change in the mission capability of aircraft assigned to the units carrying out this quality improvement initiative. Research questions were developed …


Operational Risk Management And Military Aviation Safety, Park D. Ashley Sep 1999

Operational Risk Management And Military Aviation Safety, Park D. Ashley

Theses and Dissertations

The Air Force Class A aviation mishap rate has hovered around 1.5 mishaps per 100,000 flight hours since 1985. Recent attention on Air Force accidents has caused the leadership to seek to reduce its mishap rate. The Army's Class A aviation mishap rate declined after it implemented risk management (RM) principles in 1987. This reduction caught the attention of Air Force leadership who have since stated that the application of operational risk management (ORM) is how the Air Force will reduce, even eliminate, mishaps. With current budget constraints, ORM is considered to be the most cost-effective way the Air Force …


An Exploratory Analysis Of The Responsiveness Capability Of The Air Expeditionary Wing (Aew) Concept, Robert L. Charlesworth Sep 1999

An Exploratory Analysis Of The Responsiveness Capability Of The Air Expeditionary Wing (Aew) Concept, Robert L. Charlesworth

Theses and Dissertations

Seven AEF deployments have been accomplished in the Southwest Asia area of responsibility; none have met the Air Force's stringent 72 hour criterion. This exploratory study quantifies the responsiveness capability of the AEW concept. Based on a Monte Carlo simulation methodology this study concludes that the on call AEW at Mountain Home AFB does not have the capability to meet the 72 hour criterion. Additionally, this study examined the effect of three departures from the baseline model on responsiveness capability. These departures included: increasing airlift throughput capacity, incorporating limited airlift failure, and employing an air refueling scenario. The simulation models …


The Challenge Of Maintaining Or Replacing An Aging Airlift Fleet: A Cost/Capability Analysis For The Brazilian Air Force Mobility System, Julio C. Messias Sep 1999

The Challenge Of Maintaining Or Replacing An Aging Airlift Fleet: A Cost/Capability Analysis For The Brazilian Air Force Mobility System, Julio C. Messias

Theses and Dissertations

Despite the high Operational and Support costs incurred, the Brazilian Air Force's (BAF) declining budget has led to the establishment of conservative policies that favor short run solutions for a critical BAF airlift problem of operating an aging fleet. As a result of this policy, service life extensions of older airlift aircraft are the preferred solution. Using an equal airlift capacity approach to examine the Brazilian Air Force mobility system, this research performs a cost comparison analysis between two aircraft currently in operation at Brazilian's airlift command: C-130 Hercules and C-95 Bandeirante. To accomplish the cost analysis, this research develops …


An Ex Post Facto Analysis Of E-3 Maintenance Indicators In The 552d Air Control Wing Since Reorganization Under An Aircraft Generation Squadron Concept, Larry J. Stetz Sep 1999

An Ex Post Facto Analysis Of E-3 Maintenance Indicators In The 552d Air Control Wing Since Reorganization Under An Aircraft Generation Squadron Concept, Larry J. Stetz

Theses and Dissertations

Organizational restructuring sometimes occurs in the aircraft maintenance field, yet seldom are in-depth analyses performed after the fact to see if productivity improved. In December 1995, the 552D Air Control Wing restructured its flight line maintenance into an aircraft generation squadron concept. This study looked at before and after maintenance indicators to see if productivity improved. Maintenance data was collected from December 1993 to December 1997. Nineteen maintenance indicators were identified, and the key indicators were analyzed using means comparison and regression analysis to determine if efficiency and effectiveness had increased. The variables Mission Capable rate and Man-hours per Flying …