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

Engineering Commons™

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

Air Force Institute of Technology

Theses and Dissertations

2000

Discipline
Keyword

Articles 1 - 30 of 84

Full-Text Articles in Engineering

Estimating Budget Relationships With A Leontief Input-Output Model, Guenever L. R. Shariff Dec 2000

Estimating Budget Relationships With A Leontief Input-Output Model, Guenever L. R. Shariff

Theses and Dissertations

Forty years ago, the Office of the Secretary of Defense proposed using the Leontief input-output model to assess tradeoffs in the Department of Defense's (DoD) budget. We demonstrate that the Leontief input-output model can assess tradeoffs in the Air Force's budget. To increase one part of the Air Force's budget, we need to know the interrelationships between that budget area and the other areas. In this research, we look at different methods of how the functional areas might interact. We demonstrate our methodology on two data sets - DoD and the Air Force aggregate budget data. By looking at how …

Go to article

Computer-Based Methods For Constructing Two-Level Fractional-Factorial Experimental Designs With A Requirement Set, Steven L. Forsythe Dec 2000

Computer-Based Methods For Constructing Two-Level Fractional-Factorial Experimental Designs With A Requirement Set, Steven L. Forsythe

Theses and Dissertations

This dissertation developed four methodologies for computer-aided experimental design of two-level fractional factorial designs with requirement sets (DOE/RS). The requirement sets identify all the experimental factors and the appropriate interaction terms to be evaluated in the experiment. Taguchi graphs and similar manual methods provide techniques for solving the DOE/RS problem. Unfortunately, these methods are limited because they become difficult to use as the number of factors or interaction terms exceeds ten. This research showed that the DOE/RS problem belongs to a class of difficult-to-solve problems known as NP-Complete. It is the combinatorial nature of NP-Complete problems that causes them to …

Go to article

Covalidation Of Dissimilarly Structured Models, Samuel A. Wright Dec 2000

Covalidation Of Dissimilarly Structured Models, Samuel A. Wright

Theses and Dissertations

A methodology is presented which allows comparison between models constructed under different modeling paradigms. Consider the following situation: Two models are constructed to study different aspects of the same system. One model simulates a fleet of aircraft moving a given combination of cargo and passengers from an onload point to an offload point. A second model is a linear programming model that optimizes the aircraft and route selection required for the same scenario. We develop a methodology to structure the comparison between large-scale models such as these. Models that compare favorably using this methodology are deemed covalid. Models that perform …

Go to article

Simulation And Analysis Of Wing Rock Physics For A Generic Fighter Model With Three Degrees-Of-Freedom, Ahmed Saad Aug 2000

Simulation And Analysis Of Wing Rock Physics For A Generic Fighter Model With Three Degrees-Of-Freedom, Ahmed Saad

Theses and Dissertations

Modern fighter designs have been associated with lateral self-excited oscillations own as "Wing Rock". Simulations of wing rock by flow visualization utilities have been encouraged to develop a complete understanding of the fluid mechanism that drives the motion as well as for prediction purposes. Previous wind/water tunnel simulations have been limited to a single degree-of freedom (DoF) in roll. In this study, for the first time, wing rock is computationally simulated in three DoF: roll, sideslip, and vertical motion to study the effect of adding file sideslip and vertical motion. The results are for a generic fighter model consisting of …

Go to article

Three-Dimensional Dynamic Stress Analysis Of Sandwich Panels, Victor Y. Perel Jul 2000

Three-Dimensional Dynamic Stress Analysis Of Sandwich Panels, Victor Y. Perel

Theses and Dissertations

A layerwise geometrically nonlinear theory for a thick sandwich plate was developed by introducing assumptions on a variation of transverse strains in the thickness direction of the faces and the core of the plate. An effect of transverse extensibility or compressibility of the core and the face sheets is taken into account, and the terms associated with transverse shear strain of the face sheets and the core are included into the expression for the strain energy. Displacements, obtained by integration of the strain-displacement relations, depend nonlinearly on a coordinate in the thickness direction, and are continuous at the boundaries between …

Go to article

Turbo Codes For Wireless Mobile Communication Systems Applications, Moataz M. Salah Jun 2000

Turbo Codes For Wireless Mobile Communication Systems Applications, Moataz M. Salah

Theses and Dissertations

Research in coding theory has seen many proposals aimed at the construction of powerful codes using block and convolutional codes. Recently, a new forward error control code, known as turbo code, was introduced. This new code yields very good performance (near the Shannon limit) with relatively simple component codes and large interleavers in combination with an iterative decoding process. Among the most important applications of turbo codes are wireless mobile communication systems. A significant performance metric for this application is the minimization of end-to-end delay. In this dissertation, different ways to enhance the performance of turbo codes with short frames …

Go to article

Tool-Based Integration And Code Generation Of Object Models, Michael Ray Ashby Mar 2000

Tool-Based Integration And Code Generation Of Object Models, Michael Ray Ashby

Theses and Dissertations

Today many organizations are faced with multiple large legacy data stores in different formats and the need to use data from each data store with tools based on the other data stores' formats. This thesis presents a tool-based methodology for integrating object-oriented data models with automatic generation of code. The generated code defines a global data format, generates views of global data in individual integrated data formats, and parses data from individual formats to the global formats and from the global format to the individual formats. This allows for legacy data to be translated into the global format, and all …

Go to article

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 …

Go to article

Modeling And Simulation Of Communication Systems In Opnet, David M. Banker Mar 2000

Modeling And Simulation Of Communication Systems In Opnet, David M. Banker

Theses and Dissertations

This research aims to present accurate computer models of a communication link and a Super High Frequency (SHF) radio communication system. Network Warfare Simulation (NETWARS) is a J-6 initiative aimed at modeling all communication traffic in the Department of Defense (DoD) for testing and analysis of specific real world scenarios. The AN/TSC-94 is a SHF radio system with satellite communication capabilities. The AN/TSC-94 incorporates a Direct Sequence Spread Spectrum (DSSS) radio link for certain Anti-Jam (AJ) features. A DSSS spreads' signal power over a large bandwidth, reducing power previously concentrated within the original system bandwidth. The simulations were performed using …

Go to article

A Hybrid Jump Search And Tabu Search Metaheuristic For The Unmanned Aerial Vehicle (Uav) Routing Problem, Gary W. Kinney Jr. Mar 2000

A Hybrid Jump Search And Tabu Search Metaheuristic For The Unmanned Aerial Vehicle (Uav) Routing Problem, Gary W. Kinney Jr.

Theses and Dissertations

In this research, we provide a new meta-heuristic, a jump search I tabu search hybrid, for addressing the vehicle routing problem with real-life constraints. A tour construction heuristic creates candidate solutions or jump points for the problem. A tabu search algorithm uses these jump points as starting points for a guided local search. We provide statistical analysis on the performance of our algorithm and compare it to other published algorithms. Our algorithm provides solutions within 10% of the best known solutions to benchmark problems and does so in a fraction of the time required by competing algorithms. The timeliness of …

Go to article

Post-Processing Resolution Enhancement Of Open Skies Photographic Imagery, Daniel E. Sperl Mar 2000

Post-Processing Resolution Enhancement Of Open Skies Photographic Imagery, Daniel E. Sperl

Theses and Dissertations

The Treaty on Opens Skies allows any signatory nation to fly a specifically equipped reconnaissance aircraft anywhere over the territory of any other signatory nation. For photographic images, this treaty allows for a maximum ground resolution of 30 cm. The National Air Intelligence Center (NAIC), which manages implementation of the Open Skies Treaty for the US Air Force, wants to determine if post-processing of the photographic images can improve spatial resolution beyond 30 cm, and if so, determine the improvement achievable. Results presented in this thesis show that standard linear filters (edge and sharpening) do not improve resolution significantly and …

Go to article

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. …

Go to article

Realtime Color Stereovision Processing, Byron P. Formwalt Mar 2000

Realtime Color Stereovision Processing, Byron P. Formwalt

Theses and Dissertations

Recent developments in aviation have made micro air vehicles (MAVs) a reality. These featherweight palm-sized radio-controlled flying saucers embody the future of air-to-ground combat. No one has ever successfully implemented an autonomous control system for MAVs. Because MAVs are physically small with limited energy supplies, video signals offer superiority over radar for navigational applications. This research takes a step forward in real time machine vision processing. It investigates techniques for implementing a real time stereovision processing system using two miniature color cameras. The effects of poor-quality optics are overcome by a robust algorithm, which operates in real time and achieves …

Go to article

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 …

Go to article

Evaluation Of A Method For Kinematic Gps Carrier-Phase Ambiguity Resolution Using A Network Of Reference Receivers, Brian L. Bracy Mar 2000

Evaluation Of A Method For Kinematic Gps Carrier-Phase Ambiguity Resolution Using A Network Of Reference Receivers, Brian L. Bracy

Theses and Dissertations

New applications for GPS have driven a demand for increased positioning accuracy. The emerging GPS technology particularly affects the test community. The testing equipment and method must provide a solution that is an order of magnitude more precise than the tested equipment to achieve the desired accuracy. Carrier-phase differential GPS methods using a network of reference receivers can provide the centimeter-level accuracy required over a large geographical area. This thesis evaluates the performance of a 5-receiver network over a 50 km x 120 km area of New Mexico, using a GPS network algorithm called NetAdjust. The percentage of time a …

Go to article

Development Of A Real Time Guidance System For A Kinematic Test Vehicle, Orhan Cekic Mar 2000

Development Of A Real Time Guidance System For A Kinematic Test Vehicle, Orhan Cekic

Theses and Dissertations

Differential carrier phase GPS measurements are capable of giving centimeter-level accuracies. These accuracies have many potential applications for safety and control of various types of vehicles. For this research, a real-time guidance system is developed. The real-time guidance system can be divided into two components: hardware and software. The hardware component consists of two GPS receivers (one base, one mobile), two wireless 115 Kbaud transceivers, and two laptop computers. One computer is for the reference station and other is for the mobile receiver interface and graphical display. The guided vehicle is a golf car called the Remote Sensing Autonomous Vehicle …

Go to article

Design And Validation Of An Accurate Gps Signal And Receiver Truth Model For Comparing Advanced Receiver Processing Techniques, Phillip Martin Corbell Mar 2000

Design And Validation Of An Accurate Gps Signal And Receiver Truth Model For Comparing Advanced Receiver Processing Techniques, Phillip Martin Corbell

Theses and Dissertations

Recent increases in the computational power of computers and digital signal processors have made possible new, novel signal tracking techniques in GPS receivers. One such technique is known as Direct Correlators Output Processing (DCOP). This technique replaces individual traditional tracking loops with a single Kalman Filter, which jointly processes the received signals while exploiting their correlated noises. DCOP is innovative in its potential to replace the tried and true classical signal tracking loops. It is also an enabling technology for ultra-tightly coupled GPS/INS (Global Positioning System/Inertial Navigation System). Potential benefits of these new tracking techniques include an order-of-magnitude improvement in …

Go to article

Linking Engineer Career Orientation And Human Resource Management Practices: Does Fit Affect Retention?, Cynthia M. Davis Mar 2000

Linking Engineer Career Orientation And Human Resource Management Practices: Does Fit Affect Retention?, Cynthia M. Davis

Theses and Dissertations

Turnover of the Air Force civil engineering (CE) officers is becoming increasingly important, as levels of CE Captains consistently decreases. Allen and Katz (1986) identified three career orientations of engineers based on their job preference-project, professional, and management engineers. Shepard (1958) suggested a dual-ladder promotion system to meet the cancer desires of technical and management workers. Additional research has proposed "desired" Human Resource Management (HRM) practices to facilitate the retention of each type of career-based engineer (Lee and Maurer, 1997). In an effort to determine if these career orientations, along with Air Force HRM practices, were linked to declining retention, …

Go to article

Simulations Of Flowing Supercritical N-Decane, Jeffery T. Thornburg Mar 2000

Simulations Of Flowing Supercritical N-Decane, Jeffery T. Thornburg

Theses and Dissertations

The Air Force is interested in the research of supercritical jet and rocket fuels, as well as the effects of thermally induced fuel degradation. As future flight vehicles travel at ever increasing Mach numbers, greater heat loads will be imposed upon the fuel. The primary purpose of this study is to develop a computational model for predicting fuel decomposition and bulk fuel temperatures in a stimulated heated flow reactor. The System for Thermal Diagnostic Studies (STDS), located in the Air Force Research Laboratory's Fuels Branch, is used to analyze fuels under supercritical temperatures and pressures. Computational simulations of the STDS …

Go to article

Optical Metrology Of Adaptive Membrane Mirrors, John W. Wagner Mar 2000

Optical Metrology Of Adaptive Membrane Mirrors, John W. Wagner

Theses and Dissertations

Current space-based imaging platforms are significantly constrained in both size and weight by the launch vehicle. Increased payload size and weight results in increased cost and a decrease in launch responsiveness. The USAF Scientific Advisory Board (SAB) identified "Large lightweight structures for optics and antennas" as a revolutionary primary technology to be developed for the Air Force of the 21st Century. A membrane primary mirror in a space-based imaging system has the ability to overcome current payload constraints and meet evolutionary needs of the future. The challenge of membrane optics in space is the process of implementing adaptive optics technology …

Go to article

Determining The Aircraft Requirement For Turkish Air Mobility System, Mehmet M. Ari Mar 2000

Determining The Aircraft Requirement For Turkish Air Mobility System, Mehmet M. Ari

Theses and Dissertations

Aircraft technology develops very rapidly. To keep up with the modem technology, we should update our systems and material over time. In order to do so, we should keep track of modem technologies, and implement them in our military. Turkish Air Force Command operates a vital logistical system for which routing and scheduling are done on a weekly basis. This research reviewed weekly schedules and determined the average required weekly missions which would be flown during the week. By carefully examining the job - machine formulation, this research devised a method for determining the aircraft required to perform for weekly …

Go to article

A Tabu Search For Scheduling And Rescheduling Combat Aircraft, Kevin M. Calhoun Mar 2000

A Tabu Search For Scheduling And Rescheduling Combat Aircraft, Kevin M. Calhoun

Theses and Dissertations

Scheduling an air campaign is time and labor intensive. Exacerbating the problem, combat planners use manual methods to accomplish much of this daunting but critical task. While some work has been done to automate the process, the approaches used generate schedules that must undergo major modifications before they are "flyable." Planners, therefore, distrust the results and use the automated features of the software sparingly. Additional problems arise due to the lag time between the publication of the Air Tasking Order (ATO) and the start of the ATO day. During this time, conditions change in the dynamic battlespace (aircraft break, runways …

Go to article

Damage Identification In A Real Structure Using Resonant And Anti-Resonant Frequencies, Douglas E. Gaeta Mar 2000

Damage Identification In A Real Structure Using Resonant And Anti-Resonant Frequencies, Douglas E. Gaeta

Theses and Dissertations

There exists a need to remotely monitor the structural integrity of large space structures without costly manned missions. This work focused on further damage detection characterization of the Air Force Institute of Technology's Flexible Truss Experiment (FTE). The FTE is intended to be representative of a large space structure. Several damage detection algorithms were developed and tested for the FTE using 112 different damage conditions and the one undamaged condition. The algorithms were trained using two frequency response functions (FRFs) from each damage case and then tested using the same two FRFs, but from newly acquired data. A data reduction …

Go to article

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 …

Go to article

Navigation Of Satellite Clusters, Jeffrey S. Davis Mar 2000

Navigation Of Satellite Clusters, Jeffrey S. Davis

Theses and Dissertations

The relative position determination of a cluster of satellites in near circular orbit was investigated in previous thesis work. The purpose of this thesis is to extend the concept to cover absolute position determination. A Bayes filter is used for the estimator with dynamics based on the two-body problem extended to account for J2 perturbations. Measurements consist of combining Global Positioning System (GPS) data for each satellite and range data between the satellites. Simulations were conducted investigating the accuracy obtainable when combining the measurements for input into the filter. Performance results consist of comparing the magnitude of the time error …

Go to article

Data Warehouse Techniques To Support Global On-Demand Weather Forecast Metrics, Meriellen C. Joga Mar 2000

Data Warehouse Techniques To Support Global On-Demand Weather Forecast Metrics, Meriellen C. Joga

Theses and Dissertations

Air Force pilots and other operators make crucial mission planning decisions based on weather forecasts; therefore, the ability to forecast the weather accurately is a critical issue to Air Force Weather (AFW) and its customers. The goal of this research is to provide Air Force Weather with a methodology to automate statistical data analysis for the purpose of providing on-demand metrics. A data warehousing methodology is developed and applied to the weather metrics problem in order to present an option that will facilitate on-demand metrics. On-line analytical processing (OLAP) and data mining solutions are also discussed.

Go to article

Using Simulation To Model An Army Recruiting Station With Seasonality Effects, David C. Longhorn Mar 2000

Using Simulation To Model An Army Recruiting Station With Seasonality Effects, David C. Longhorn

Theses and Dissertations

One of the toughest jobs in the Army is that of the recruiter. Recruiters are tasked with the awesome job of convincing young men and women to lay down their lives and freedoms for their country, and oftentimes for less money than can be earned in the safer environment of America's booming economy. Recruiters face enormous pressure from commanders to meet the mandated Army manning levels set each year by Congress. As the Army begins the 21st century, it is faced with having to support an increasing number of deployments with fewer soldiers. Soldiers face long and difficult days with …

Go to article

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 …

Go to article

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 …

Go to article

Mission Route Planning With Multiple Aircraft & Targets Using Parallel A* Algorithm, Ergin Sezer Mar 2000

Mission Route Planning With Multiple Aircraft & Targets Using Parallel A* Algorithm, Ergin Sezer

Theses and Dissertations

The general Mission Route Planning (MRP) Problem is the process of selecting an aircraft flight path in order to fly from a starting point through defended terrain to target(s), and return to a safe destination. MRP is a three-dimensional, multi-criteria path search. Planning of aircraft routes involves an elaborate search through numerous possibilities, which can severely task the resources of the system being used to compute the routes. Operational systems can take up to a day to arrive at a solution due to the combinatorial nature of the problem, which is not acceptable, because time is critical in aviation. Also, …

Go to article

Next Last