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Air Force Institute of Technology

1998

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Articles 61 - 75 of 75

Full-Text Articles in Engineering

Cross-Resolution Combat Model Calibration Using Bootstrap Sampling, Bryan S. Livergood Mar 1998

Cross-Resolution Combat Model Calibration Using Bootstrap Sampling, Bryan S. Livergood

Theses and Dissertations

The US Air Force uses many combat simulation models to assist them in performing combat analyses. BRAWLER is a high-resolution air-to-air combat simulation model used for engagement-level analyses of few-on-few air combat. THUNDER is a low-resolution combat simulation model used for campaign-level analyses of theater-level warfare. BRAWLER is frequently used to ensure that THUNDER air-to-air inputs are valid. This thesis describes the confederation of THUNDER and BRAWLER by clearly showing how one particular BRAWLER output, the effectiveness of a missile type, is transformed into THUNDER air-to-air input data. Since BRAWLER is a stochastic simulation model, it is necessary to replicate …

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Optimizing The Efficiency Of A Multi-Stage Axial-Flow Compressor: An Application Of Stage-Wise Optimization, Shawn A. Miller Mar 1998

Optimizing The Efficiency Of A Multi-Stage Axial-Flow Compressor: An Application Of Stage-Wise Optimization, Shawn A. Miller

Theses and Dissertations

The development of jet engines has become an integral part of maintaining air superiority. In order to achieve the most advanced engine, research has turned to traditional optimization methods to aid in creating new engine designs. To develop simplified mathematical models representative of the engine, the engine can be separated into its components. A jet engine has three major elements, the compressor, combustion chamber and turbine. This research attempts to make an initial analysis of a two stage compressor to determine values of blade angles and spacing to chord ratios for both stages that produce the highest possible efficiency for …

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Improved Mathematical Modeling For Gps Based Navigation, Salvatore Nardi Mar 1998

Improved Mathematical Modeling For Gps Based Navigation, Salvatore Nardi

Theses and Dissertations

This thesis is concerned with the development of new closed form GPS position determination algorithms that work in the presence of pseudorange measurement noise. The mathematical derivation of two closed form algorithms, based on stochastic modeling and estimation techniques, is presented. The algorithms provide an estimate of the GPS solution parameters (viz., the user position and the user clock bias) as well as the estimation error covariance. The experimental results are analyzed by comparison to the baseline results from the conventional Iterative Least Squares (ILS) algorithm. In typical GPS scenarios, the closed form algorithms are extremely sensitive to noise, making …

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Preliminary Design Of A Joint Simulation, Analysis, And Wargaming Center For The Turkish General Staff, Oguz Okuyucu Mar 1998

Preliminary Design Of A Joint Simulation, Analysis, And Wargaming Center For The Turkish General Staff, Oguz Okuyucu

Theses and Dissertations

This study develops a framework for the design of a Joint Simulation, Analysis, and Wargaming Center (JSAWC). JSAWC is proposed as the primary decision support center for the Turkish General Staff. The complexity of warfare systems and the fog of future wars make military planning, problem solving, and decision making processes difficult to accomplish without using computerized analysis support tools. The proposed JSAWC will use modeling and simulation technology to provide analytical support for Turkish military decision-makers and planners in operations planning, force structuring, and training. An iterative systems engineering process is defined and applied to the primary design of …

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A Variable-Complexity Modeling Approach To Scramjet Fuel Injection Array Design Optimization, Michael D. Payne Mar 1998

A Variable-Complexity Modeling Approach To Scramjet Fuel Injection Array Design Optimization, Michael D. Payne

Theses and Dissertations

The analysis of fuel air mixing in a scramjet is often accomplished either with Computational Fluid Dynamics (CFD) algorithms or through experimental research. These approaches, while accurate and reliable, are extremely expensive and thus not well suited for use with conventional design optimization methods. In this investigation, Variable Complexity Modeling (VCM) is used to significantly reduce the number of complex, expensive analyses required to optimize the design of a scramjet fuel injection array. A design problem formulation for a lateral transverse injection array is developed and a VCM approach to design optimization is conducted in two stages. Initially, a simplified …

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Analysis Of Alternatives: Multivariate Considerations, John J. Siegner Mar 1998

Analysis Of Alternatives: Multivariate Considerations, John J. Siegner

Theses and Dissertations

The Aeronautical System Center (ASC) is developing a Simulation and Analysis Facility (SIMAF) that will link models, simulations, hardware-in-the-loop, and system-in-the-loop resources to create a robust virtual environment supporting assessment of alternate systems in the defense acquisition process. ENS is assisting ASC with scenario development, experimental design, and battleroom visualization efforts for a SIMAF capability demonstration. This thesis uses multivariate analysis and visualization tools to develop an approach for reducing the dimensionality of multiple campaign level measures of effectiveness for a notional Analysis of Alternatives (AoA) study. Additionally, the thesis advances an AoA visualization paradigm for the SIMAF capability demonstration. …

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Effect Of High Free Stream Turbulence On Film Cooling Using Double Row Of 30° Slant-Hole Injectors, Lilith I. Sorensen Mar 1998

Effect Of High Free Stream Turbulence On Film Cooling Using Double Row Of 30° Slant-Hole Injectors, Lilith I. Sorensen

Theses and Dissertations

In this study free stream turbulence levels from 7.3% to 17.8% are applied to film cooling over a flat plate with two rows of 30° slant holes using a wall jet as the main stream air supply and source of turbulence. Blowing ratios are varied from 0.25 to 2.0 and free stream velocities at injection range from 10 m/s to 85 m/s. A constant density ratio of 1.07 is kept throughout the experiment. Results show that for different magnitudes of blowing ratio free stream turbulence has a different influence on effectiveness. At the forward stations, where blow off was present …

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The Measurement Of Human Intellectual Capital In The United States Air Force, Thomas J. Wagner Mar 1998

The Measurement Of Human Intellectual Capital In The United States Air Force, Thomas J. Wagner

Theses and Dissertations

For centuries, companies used basically the same accounting system developed in the fifteenth century to measure economic performance. Through much of this period the tangible value of a firm, its plants, property and equipment, was closely related to the market value of the firm. With the dawning of the information age, America has evolved from a manufacturing based economy to a service oriented economy. Closely related to this change from a blue collar to white collar workplace has been the widening gap between the market value of a company and its tangible assets. Roughly equal before, now the tangible assets …

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An Analytical Tool To Assess Aeromedical Evacuation Systems For The Department Of Defense, Scott A. Wilhelm Mar 1998

An Analytical Tool To Assess Aeromedical Evacuation Systems For The Department Of Defense, Scott A. Wilhelm

Theses and Dissertations

The research was commissioned by, and conducted for, the HQ AMC Surgeon General to assist him in making a hard decision. Should the McDonnell-Douglas C-9A Nightingale be replaced, and, if so, with what? Using tools based in Keeney's Value-Focused Thinking methodology, the SG's values for this decision were quantified, alternatives that addressed these values were generated, and those alternatives were evaluated using his values to suggest preferred alternatives.

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A Value Focused Thinking Approach To Academic Course Scheduling, Shane A. Knighton Mar 1998

A Value Focused Thinking Approach To Academic Course Scheduling, Shane A. Knighton

Theses and Dissertations

In 1997, the School of Engineering of the United States Air Force Institute of Technology began exploring ways of automating the academic course scheduling process. The administration desired an expedient approach for course scheduling which supports the institute's mission of "providing scientific and technological education" to officers from all branches of military service, as well as international military forces. The scheduling approach needed to be flexible, efficient, and represent the institute's values and principles. Decision Analysis (DA) and specifically, Value Focused Thinking (VFT), is used to decompose the complex problem of academic course scheduling and determine the factors that are …

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Real Time Detection Of Anomalous Satellite Behavior Has Ground Based Telescope Images, Geoffrey S. Maron Mar 1998

Real Time Detection Of Anomalous Satellite Behavior Has Ground Based Telescope Images, Geoffrey S. Maron

Theses and Dissertations

Air Force analysts are faced with the task of monitoring satellites with ground based telescopes. Images are collected and analyzed in a time consuming and subjective effort to detect any behavior that is anomalous. This research maximizes use of a priori information to create an automated, real time satellite behavior classification tool. Using modeling software and knowledge of a satellite's orbit, reference imagery is created for each measured image in a satellite pass. Features are extracted from the measured and reference image pairs that provide good overall Gaussian classification accuracy (85%), reduce the dimensionality of the problem (from 32,768 down …

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An Advanced Visualization Method For An Operations Research Analysis, Steven C. Oimoen Mar 1998

An Advanced Visualization Method For An Operations Research Analysis, Steven C. Oimoen

Theses and Dissertations

Visualizing multidimensional data using only two dimensions and conventional visualization techniques limits the understanding of the data set. Underlying structures or patterns within the data can easily go unnoticed. In order to gain additional insight into an analysis, incorporation of visualization and multidimensional graphics into the analysis results should be accomplished. The results must ensure that the information portrayed is not misleading or misunderstood. The integrity of the data must be preserved throughout the transformation. The primary objective of this research effort is to identify techniques to visualize multidimensional data and then develop a software tool to display the multidimensional …

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Verification And Validation Of Faarr Model And Data Envelopment Analysis Models For United States Army Recruiting, Gene M. Piskator Mar 1998

Verification And Validation Of Faarr Model And Data Envelopment Analysis Models For United States Army Recruiting, Gene M. Piskator

Theses and Dissertations

This research has two objectives-to verify and validate the U.S. Army's Forecast and Allocation of Army Recruiting Resources (FAARR) model and to develop a Data Envelopment Analysis (DEA) modeling strategy. First, the FAARR model was verified using a simulation of a known production function and validated using sensitivity analysis and ex-post forecasts. FAARR model forecasts were not accurate and were extremely sensitive to any changes in the model's linear programming constraints and to changes in recruiting resource levels. Second, this research describes a three phase modeling strategy to build accurate DEA models. DEA has become a popular tool to evaluate …

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Embedding A Reactive Tabu Search Heuristic In Unmanned Aerial Vehicle Simulations, Joel L. Ryan Mar 1998

Embedding A Reactive Tabu Search Heuristic In Unmanned Aerial Vehicle Simulations, Joel L. Ryan

Theses and Dissertations

We apply a Reactive Tabu Search (RTS) heuristic within a discrete event simulation to solve routing problems for Unmanned Aerial Vehicles (UAVs). Our formulation represents this problem as a multiple Traveling Salesman Problem with time windows (mTSPTW), with the objective of attaining a specified level of target coverage using a minimum number of vehicles. Incorporating weather and probability of UAV survival at each target as random inputs, the RTS heuristic in the simulation searches for the best solution in each realization of the problem scenario in order to identify those routes that are robust to variations in weather, threat, or …

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Optimum Preventive Maintenance Policies For The Amraam Missile, Scott J. Ruflin Feb 1998

Optimum Preventive Maintenance Policies For The Amraam Missile, Scott J. Ruflin

Theses and Dissertations

The overall objective of this research effort was to formulate a preventive maintenance strategy for AMRAAM missiles subject to extended captive carry flight time. A preventive maintenance policy is only applicable if the item in question is aging, or deteriorating with time. Therefore, a supporting objective of this research is to characterize the aging process of the missile system through a non-parametric analysis of its Mean Residual Life (MRL) function. Three non-parametric, censored-data MRL function estimation techniques discussed in the literature are examined via a numerical example. All three estimation techniques provide MRL functions that exhibit greatly exaggerated decreasing trends …

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