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Neural Network Modeling Of The Head-Related Transfer Function, Damion Reinhardt Mar 1998

Neural Network Modeling Of The Head-Related Transfer Function, Damion Reinhardt

Theses and Dissertations

Battlefield synthesis of 3-D audio may require the interpolation and compression of head-related transfer function (HRTF) data. This thesis is an implementation of a functional model of the HRTF using artificial neural networks (ANNs), the model provides both compression and interpolation.

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Analyzing Horizontal Distances Between Wsr-88d Thunderstorm Centroids And Cloud-To-Ground Lightning Strikes, Steve L. Renner Mar 1998

Analyzing Horizontal Distances Between Wsr-88d Thunderstorm Centroids And Cloud-To-Ground Lightning Strikes, Steve L. Renner

Theses and Dissertations

On April 29, 1996, lightning struck the airfield at Hurlburt Field, FL, killing one Airmen and injuring ten others. This cloud to ground lightning strike hit eight minutes after a lightning advisory was canceled. At the time of the strike, thunderstorms were observed 7 to 10 miles north and south of the airfield. The incident raised questions about Air Force Weather Agency's lightning criteria. Soon after the incident, a Lightning Safety Review Panel was assembled to determine the adequacy of lightning advisories. One of the questions posed to the panel was could an incident like Hurlburt happen again? The review …

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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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A Game-Theoretic Improvement Model For Stochastic Networks: Reliability Vs. Throughput, Jeffrey A. Schavland Mar 1998

A Game-Theoretic Improvement Model For Stochastic Networks: Reliability Vs. Throughput, Jeffrey A. Schavland

Theses and Dissertations

Prescriptive models used to allocate resources for network improvement traditionally have used reliability or flow as Measures of Effectiveness (MOEs). Such metrics do not give value to efforts which make a component more difficult to exploit. This study developed an entirely new MOE for stochastic network improvement, flow damage utility, which uses a two person, zero-sum, non-cooperative game to optimize a probabilistic network for an estimate of expected flow minus performance degradation after a worst case component loss. A multiple criteria optimization problem that uses flow damage utility and an analogous, previously developed metric for the reliability problem is used …

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A Validation Study Of The Air Force Weather Agency (Afwa) Jetrax Contrail Forecast Algorithm, Jeffrey D. Shull Mar 1998

A Validation Study Of The Air Force Weather Agency (Afwa) Jetrax Contrail Forecast Algorithm, Jeffrey D. Shull

Theses and Dissertations

Accurate contrail forecasts allow pilots to avoid levels of the atmosphere which are conducive to contrail formation, reducing their likelihood of being visually detected by enemy forces. The primary objective of this thesis is to evaluate the performance of the JETRAX contrail forecast algorithm currently used by the Air Force Weather Agency to support military air operations. A total of 397 ground-based contrail observations were collected at Wright-Patterson Air Force Base on 27 different days. Observations were collected with the aid of air traffic control radar, which greatly facilitated the positive identification of overflying aircraft and provided necessary information such …

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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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The Application Of Sequential Convex Programming To Large-Scale Structural Optimization Problems, Todd A. Sriver Mar 1998

The Application Of Sequential Convex Programming To Large-Scale Structural Optimization Problems, Todd A. Sriver

Theses and Dissertations

Structural design problems are often modeled using finite element methods. Such models are often characterized by constraint functions that are not explicitly defined in terms of the design variables. These functions are typically evaluated through numerical finite element analysis (FEA). Optimizing large-scale structural design models requires computationally expensive FEAs to obtain function and gradient values. An optimization approach which uses the SCP sequential convex programming algorithm of Zillober, integrated as the optimizer in the Automated Structural Optimization System (ASTROS), is tested. The traditional approach forms an explicitly defined approximate subproblem at each design iteration that is solved using the method …

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Damage Detection Using Pattern Classifiers, Eric D. Swenson Mar 1998

Damage Detection Using Pattern Classifiers, Eric D. Swenson

Theses and Dissertations

The research focused on developing and tuning finite element models to train pattern classifiers to detect and locate damage in a real structure. The research was broken into three distinct phases: finite element (FE) model development, FE model tuning, and pattern classifier training and testing. In the finite element development phase, a low order FE model called the baseline model and a high order model called the stiff model were created. In the FE model tuning phase, these FE models were tuned using measured Frequency Response Functions (FRFs), and the results were compared with previous research in which tuning was …

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Using Bayesian Statistics In Operational Testing, Thuan H. Tran Mar 1998

Using Bayesian Statistics In Operational Testing, Thuan H. Tran

Theses and Dissertations

This research explored the applicability of Bayesian methods to the problem of determining the reliability of a series system, a parallel system, and a bridge system. The time to failure of each component in each system is assumed to be exponentially distributed. A basic exponential case and a basic binomial case are also evaluated. In general, using simulated data and real data when possible, the Bayesian methods produced confidence intervals that were much tighter than the classical inference methods, thus allowing a decision maker to have higher confidence in making a decision. System level data and aggregated component level data …

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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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Improving Cape Canaveral's Day-2 Thunderstorm Forecasting Using Meso-Eta Numerical Model Output, Christian S. Wohlwend Mar 1998

Improving Cape Canaveral's Day-2 Thunderstorm Forecasting Using Meso-Eta Numerical Model Output, Christian S. Wohlwend

Theses and Dissertations

The 45th Weather Squadron (WS) is responsible for the protection of billions of dollars worth of Air Force and NASA equipment from weather hazards. They produce a seven day planning forecast as one tool to support the space launch community. Improving this forecast can potentially save millions of dollars of government funds. This research focuses on the feasibility of improving the day two thunderstorm forecast by applying Meso Eta numerical forecasts to the Neumann-Pfeffer Thunderstorm Index (NPTI). The NPTI is currently used by the 45th WS for same day thunderstorm probability forecasting utilizing the morning radiosonde as input. The perfect …

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Multiple Model Adaptive Estimation Using Filter Spawning, Kenneth A. Fisher Mar 1998

Multiple Model Adaptive Estimation Using Filter Spawning, Kenneth A. Fisher

Theses and Dissertations

Multiple Model Adaptive Estimation with Filter Spawning is used to detect and estimate partial actuator failures on the VISTA F-16. The truth model is a full six-degree-of-freedom simulation provided by Calspan and General Dynamics. The design models are chosen as 13-state linearized models, including first order actuator models. Actuator failures are incorporated into the truth model and design model assuming a "failure to free stream . Filter Spawning is used to include additional filters with partial actuator failure hypotheses into the Multiple Model Adaptive Estimation (MMAE) bank. The spawned filters are based on varying degrees of partial failures (in terms …

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The Influence Of Surface Roughness On Supersonic High Reynolds Number Turbulent Boundary Layer Flow, Robert M. Latin Mar 1998

The Influence Of Surface Roughness On Supersonic High Reynolds Number Turbulent Boundary Layer Flow, Robert M. Latin

Theses and Dissertations

A comprehensive study of rough-wall high speed (M=2.9) high Reynolds number (Re/m = 1.9 x 107) turbulent boundary layer flow was performed consisting of experimental, analytical, and numerical methods. Six wall topologies consisting of a smooth and five rough surfaces (two and three dimensional machined roughness plates; and 80, 36, and 20 grit sand-grain roughened plates) were studied. A confocal laser scan microscope was used to measure the topography of the sand grain roughnesses. The experimental measurement techniques included a convention Pitot pressure probe, laser Doppler velocimetry, hot wire anemometry; color schlieren and laser …

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Optical Physics Of Microcavity Surface Emitting Lasers, Michael J. Noble Mar 1998

Optical Physics Of Microcavity Surface Emitting Lasers, Michael J. Noble

Theses and Dissertations

This dissertation consists of an in-depth theoretical analysis of the optical impact of transverse index confinement on the lasing modes of microcavity surface emitting lasers. Two different variational techniques were employed to calculate the relevant optical laser parameters: (1) modal resonance, field profile, (2) confinement factor, and (3) threshold gain. Through a semianalytic field analysis, two new confinement related effects were discovered: (1) a polarization dependent change in mirror reflectance with aperture radius, and (2) a mode dependent blueshift. Through a numerical field analysis, the physical mechanisms governing diffraction were ascertained. These are: (1) the transverse confinement of the optical …

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Linear Reconstruction Of Non-Stationary Image Ensembles Incorporating Blur And Noise Models, Stephen D. Ford Mar 1998

Linear Reconstruction Of Non-Stationary Image Ensembles Incorporating Blur And Noise Models, Stephen D. Ford

Theses and Dissertations

Two new linear reconstruction techniques are developed to improve the resolution of images collected by ground-based telescopes imaging through atmospheric turbulence. The classical approach involves the application of constrained least squares (CLS) to the deconvolution from wavefront sensing (DWFS) technique. The new algorithm incorporates blur and noise models to select the appropriate regularization constant automatically. In all cases examined, the Newton-Raphson minimization converged to a solution in less than 10 iterations. The non-iterative Bayesian approach involves the development of a new vector Wiener filter which is optimal with respect to mean square error (MSE) for a non-stationary object class degraded …

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Analysis Of Turbulence Models As Applied To Two- And Three-Dimensional Injection Flows, Clarence R. Chenault Mar 1998

Analysis Of Turbulence Models As Applied To Two- And Three-Dimensional Injection Flows, Clarence R. Chenault

Theses and Dissertations

A steady state solution of the full, three dimensional Favre averaged Navier Stokes equations, coupled with a second order Reynolds stress turbulence model (RSTM) and an eddy viscosity model were used to numerically simulate oblique injection into supersonic flow. Numerical results were compared to experimental data and the turbulence models were evaluated for accurate prediction of thermomechanical mean flow variables, Reynolds stresses, flowfield shock structure and boundary layer phenomena. The RSTM simulation resulted in physically consistent and accurate predictions for the mean flow and turbulent quantities. Simulations with the eddy viscosity model resulted in non-physical and inconsistent turbulence predictions. RSTM …

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Modified Multiple Model Adaptive Estimation (M3Ae) For Simultaneous Parameter And State Estimation, Mikel M. Miller Mar 1998

Modified Multiple Model Adaptive Estimation (M3Ae) For Simultaneous Parameter And State Estimation, Mikel M. Miller

Theses and Dissertations

In many estimation problems, it is desired to estimate system states and parameters simultaneously. However, inherent to traditional estimation architectures of the past, the designer has had to make a trade-off decision between designs intended for accurate state estimation versus designs concerned with accurate parameter estimation. This research develops one solution to this trade-off decision by proposing a new architecture based on Kalman filtering (KF) and Multiple Model Adaptive Estimation (MMAE) techniques. This new architecture, the Modified-MMAE (M3AE), exploits the benefits of an MMAE designed for accurate parameter estimation, and yet performs at least as well in state …

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Anderson-Darling And Cramer-Von Mises Based Goodness-Of-Fit Tests For The Weibull Distribution With Known Shape Using Normalized Spacings, Eric W. Frisco Mar 1998

Anderson-Darling And Cramer-Von Mises Based Goodness-Of-Fit Tests For The Weibull Distribution With Known Shape Using Normalized Spacings, Eric W. Frisco

Theses and Dissertations

Two new goodness-of-fit tests are developed for the three-parameter Weibull distribution with known shape parameter. These procedures eliminate the need for estimating the unknown location and scale parameters prior to initiating the tests and are easily adapted for censored data. This is accomplished by employing the Anderson-Darling and Cramer-von Mises statistics based on the normalized spacings of the sample data. Critical values of the new tests are obtained for common significance levels by large Monte Carlo simulations for shapes 0.5(0.5)4.0 and sample sizes 5(5)40 with up to 40% censoring (Type II) from the left and/or right. An extensive Monte Carlo …

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An Operational Review Of Air Campaign Planning Automation, William R. Haas Mar 1998

An Operational Review Of Air Campaign Planning Automation, William R. Haas

Theses and Dissertations

The air campaign planning process is a complex and dynamic process. Operations research has been applied to this problem to shorten the planning cycle with mixed results. The Joint Force Air Component Commander Planning Tool was developed as an air campaign planning aid. It uses the Conventional Targeting and Effectiveness Model (CTEM) as the force analysis model for master air attack plan (MAAP) planning. This thesis reviews the limitations and assumptions of CTEM and CTEM in JPT from and operational perspective. A new approach to using models in air campaign planning, collaborative planning, is being developed for use with JPT. …

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Regression Analysis Of Radar Measured Optical Turbulence With Synoptic Scale Meteorological Variables, Diana L. Hajek Mar 1998

Regression Analysis Of Radar Measured Optical Turbulence With Synoptic Scale Meteorological Variables, Diana L. Hajek

Theses and Dissertations

A key issue to the USAF's Airborne Laser (ABL) program is the ability to accurately predict the level of optical turbulence that the ABL will encounter at its flight levels. The optical turbulence must be characterized so that the range and range variation of the ABL can be determined. Gravity wave spectra resulting from frontal or jet stream passage are presumed to cause layers of optical turbulence; however, exact relationships between optical turbulence and synoptic scale meteorological phenomena are unclear. This study assesses the statistical relationship between optical turbulence and synoptic scale variables through multiple linear regression. The optical turbulence …

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Investigating Sorbent Geometry Response Surfaces From Sorption Rate Data, H. Michael Harrison Mar 1998

Investigating Sorbent Geometry Response Surfaces From Sorption Rate Data, H. Michael Harrison

Theses and Dissertations

Sorption and desorption of hydrophobic organic compounds (HOCs) into soil particles occurs at Air Force contamination sites. Long-term desorption extends clean up time, costing billions. Accurately modeling desorption will reduce costs and improve clean up designs. State of the art models depict soil as uniform spherical particles which lose the effect of longer sorption path lengths. An alternate approach, the multiple sites in series (MSS) model, describes the sorption capacity of a mixture of soil particle sizes and shapes using a composite particle defined by a two parameter statistical distribution. When the MSS model uses a general radial geometry function …

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Evaluation Of Satellite Microwave Derived Surface Temperature Algorithms For The Period August 1996 To February 1997, Charles H. Harris Mar 1998

Evaluation Of Satellite Microwave Derived Surface Temperature Algorithms For The Period August 1996 To February 1997, Charles H. Harris

Theses and Dissertations

The Air Force Weather Agency (AFWA) has two operational algorithms that derive surface temperatures from microwave observations taken by the Special Sensor Microwave Imager (SSM/I) which rides aboard space platforms of the Defense Meteorological Satellite Program (DMSP). The algorithm called Temperature from Satellite Microwave Imager (TS) is used to analyze global cloud coverage. The second algorithm is fittingly called Calibration and Validation (CV), as it was the algorithm used to calibrate and validate the first SSM/I in 1987. Multiple linear regression defined the algorithms from empirically gathered brightness temperatures and simultaneous surface temperatures. The key questions were how much data …

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An Evaluation Of Frequency Domain Ensemble Averaging To Improve Aircraft Stability Derivative Estimation, Lawrence M. Hoffman Mar 1998

An Evaluation Of Frequency Domain Ensemble Averaging To Improve Aircraft Stability Derivative Estimation, Lawrence M. Hoffman

Theses and Dissertations

This research evaluated a process to improve aircraft stability derivative estimation results. The Have Derivatives process used overlap ensemble averaging in the frequency domain to minimize noise on the original time domain signals. The process estimated average complex frequency response functions that were then transformed back into the time domain as a set of discrete pulse responses with far less noise than the original signals. These clean signals were used in a parameter estimation program to estimate better stability derivatives than were estimated with the original noisy signals. Both simulation and flight test data were used to study the effects …

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Nowcasting Thunderstorms At Cape Canaveral, Florida, Using An Improved Neumann-Pfeffer Thunderstorm Index, Cindy L. Howell Mar 1998

Nowcasting Thunderstorms At Cape Canaveral, Florida, Using An Improved Neumann-Pfeffer Thunderstorm Index, Cindy L. Howell

Theses and Dissertations

The Neumann-Pfeffer Thunderstorm Index (NPTI) is used daily by the 45th Weather Squadron during the convective season to estimate the probability of afternoon thunderstorms. The current I , developed by Charles J. Neumann in the 1960s, i based on only 13 years of data taken over 30 years ago. The index was in desperate need of an upgrade. Following the multiple regression techniques outlined by Neumann, this thesis examines whether or not including additional data would improve the performance of the NPTI. After performing the multiple regressions and retuning the regression coefficients, both NPTs were validated using a 2-year independent …

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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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A Network Disruption Modeling Tool, James A. Leinart Mar 1998

A Network Disruption Modeling Tool, James A. Leinart

Theses and Dissertations

Given that network disruption has been identified as a military objective and C2-attack has been identified as the mechanism to accomplish this objective, a target set must be acquired and priorities assigned to each target set. In order to move beyond subjective target prioritization, development and implementation of a methodology and model, that quantitatively measures the value of each target in achieving the objective, is needed in prioritizing targets. This thesis effort uses a vertex cut-set algorithm on a transformation of the graph representing a notional network of interest. The cut-sets generated represent potential target sets. Value-focused thinking and decision …

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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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Forecasting Wet Microbursts Associated With Summertime Airmass Thunderstorms Over The Southeastern United States, James B. Mackey Mar 1998

Forecasting Wet Microbursts Associated With Summertime Airmass Thunderstorms Over The Southeastern United States, James B. Mackey

Theses and Dissertations

Microbursts are intense downbursts from thunderstorms that affect an area less than 4 km and have a lifespan less than 10 minutes. Wet microbursts are associated with heavy precipitation and are common in the eastern and southeastern part of the country. The greatest threat from microbursts is to low flying aircraft, where the rapid fluctuations in horizontal and vertical airflow create tremendous shear zones. Microbursts have been determined to be the causal factor behind at least three major aircraft accidents resulting in numerous fatalities. Due to the short lifespan of microbursts, they often strike without warning and pose a serious …

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Application Of Decision Analysis To Evaluate Alternative Research And Development Investments, Michael J. Artelli Mar 1998

Application Of Decision Analysis To Evaluate Alternative Research And Development Investments, Michael J. Artelli

Theses and Dissertations

This thesis is an application of decision analysis techniques to the problem of evaluating competing research and development investments and selecting the best portfolio from among the alternatives. In contrast to the current ad hoc approach, decision analysis provides an explicit and easily explained rationale for investment choices, complete and consistent incorporation of multiple objectives, and direct insight into the effects of uncertain investment returns. A hierarchical objective decomposition was used to capture the user's preference structure. The hierarchy was then used to develop a computer-based decision aid to allow the users to quickly and consistently evaluate technology investment options. …

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