Engineering Commons^™

Modeling Space In The Air Force Command Exercise System (Aces), Robert Payne Jr.

Theses and Dissertations

In response to the increased influence of space forces on today's battlefield, several theater level models were analyzed for the presentation of space forces. These models were the Extended Air Defense Simulation (EADSIM), the Joint Theater Level Simulation (JTLS), the Integrated Theater Engagement Model (ITEM), the Tactical Warfare Model (TACWAR), Thunder, Janus, and the Aggregate Level Simulation Protocol (ALSP). While ALSP is not a model but a simulation protocol connecting various models, it was studied because it appears to be the future of modeling. The consensus of the analysis was that space forces are virtually ignored by most of the …

Text-Independent, Open-Set Speaker Recognition, Stephen V. Pellissier

Theses and Dissertations

Speaker recognition, like other biometric personal identification techniques, depends upon a person's intrinsic characteristics. A realistically viable system must be capable of dealing with the open-set task. This effort attacks the open-set task, identifying the best features to use, and proposes the use of a fuzzy classifier followed by hypothesis testing as a model for text-independent, open-set speaker recognition. Using the TIMIT corpus and Rome Laboratory's GREENFLAG tactical communications corpus, this thesis demonstrates that the proposed system succeeded in open-set speaker recognition. Considering the fact that extremely short utterances were used to train the system (compared to other closed-set speaker …

The Effects Of Changing Force Structure On Thunder Output, Michael R. Farmer

Theses and Dissertations

In today's reduction of America's national defense, campaign level models are being used more in the development of force structure. The effects of drawdown are of significant interest to those at the highest levels of authority. Campaign models can bring those high ranking officials the answers they seek with high confidence. THUNDER is a campaign model used frequently by the United States Air Force and many of its contractors. The effects of changing the force structure within THUNDER require modifying variables before executing a new experimental run. Changes in such issues as force structure cannot be immediately addressed. Response Surface …

Replicative Use Of An External Model In Simulation Variance Reduction, Thomas H. Irish

Theses and Dissertations

The use of control variates is a well-known variance reduction technique for discrete event simulation experiments. Currently, internal control variates are used almost exclusively by practitioners and researchers when using control variates. The primary objective of this study is to explore the variance reduction achieved by the replicative use of an external, analytical model to generate control variates. Performance for the analytical control variates is compared to the performance of typical internal and external control variates for both an open and a closed queueing network. Performance measures used are confidence interval width reduction, realized coverage, and estimated Mean Square Error. …

Forecasting And Explanatory Models For Middle Eastern Defense Budgets: A Case Study Of Saudi Arabia, Robert S. Renfro Ii

Theses and Dissertations

This thesis focuses on means of forecasting Saudi Arabian military expenditures and the effect of such expenditures on the United States. Saudi Arabia is one of the largest purchasers of American arms and will continue to be for many years. Saudi Arabia has experienced several recent changes in economic and government policy. Using exponential smoothing techniques and linear regression, we isolated several trends in Saudi Arabian military expenditures. Using two linear regression models, military expenditures were then forecast with excellent results. The first model considered the assumption that Gulf War spending would continue. This model uses Saudi Arabian Gross Domestic …

Airlift System Sensitivity To Perturbed Time-Phased Force Deployment Data, Glenn G. Rousseau

Theses and Dissertations

This research evaluated the effects of perturbations in time phased force deployment data (TPFDD) on airlift system performance. Four characteristics of two TPFDD files were perturbed according to a 2(4-1) fractional factorial experimental design and then fed into the Airlift Flow Module (AFM) simulation. Specifically, small, constrained perturbations were made to the specified locations, the timeline, the amounts of cargo and passengers, and the proportion of outsize and oversize cargo categories. The effects these perturbations had on AFM output were interpreted using factor analysis. The computed factor scores, when plotted against one another, provided sensitivity plots, graphically depicting the sensitivity …

Requirement For C-130 Aircraft In The Intratheater Korean Scenario, Philip B. Oglesby

Theses and Dissertations

In an effort to provide a timely and reasonably accurate methodology for determining C-130 intratheater airlift requirements, this research concentrated on a rough-cut capacity approach using a straight forward linear programming spreadsheet model. To provide more detailed analysis, a more sophisticated linear program was investigated. Specifically, the spreadsheet model calculated the minimum number of C-130s required to carry required cargo, passenger, and aeromedical loads based on user-defined daily requirements. For a given scenario, inputs include the daily requirements and the expected capacity for C-130 aircraft, trucks, and 22-car trains. Included in the capacity inputs are the number of daily cycles …

Modeling Mobility Engineering In A Theater Level Combat Model, Brian K. Hobson

Theses and Dissertations

This thesis describes the development of a methodology to model theater-level mobility engineering assets in the Joint Staff's Joint Warfare Analysis Experimental Prototype (JWAEP) and to quantify the joint and Army doctrine that guides the task organization of engineers for combat and which quantifies engineer mobility effects in combat. The methodology incorporates theater-level mobility engineering assets into the JWAEP by using Mission, Enemy, Troops available, Terrain, and Time (MET-T principles which reflect joint and Army doctrine, and combines them with the existing basic concepts in other theater-level models. Additional aspects of the problem include determining the manmade and natural obstacles' …

Modeling Diminishing Marginal Returns: An Application To The Aircraft Availability Model, Wayne L. Zorn

Theses and Dissertations

The Aircraft Availability Model (AAM) provides the Air Force with a worldwide peacetime requirement for reparable spare parts. This research models AAM methodology as it relates to the concept of diminishing marginal returns in resource application. Three separate modeling techniques are investigated with the goal of reformulating the AAM as a mathematical programming model that provides a comparable solution and a capable tool for the conduct of sensitivity analysis. The general formulations presented here are continuous non-linear, continuous linear, and piecewise linear discrete/continuous models. Two formulations of the piecewise linear discrete/continuous model are presented. The piecewise linear model based on …

A Response Surface Methodology Approach To Groundwater Model Calibration, Jeffrey B. Rowland

Theses and Dissertations

This thesis examined the effect of parameter bounding, a reduced data set, and data enrichment techniques on a response surface methodology (RSM) approach to groundwater model calibration. The four phases of the study included a calibration using a very dense data matrix, a calibration using a sparse calibration matrix, an evaluation of several data enrichment techniques, and a calibration using a data matrix enlarged with the use of the best enrichment technique. All calibrations were conducted using only a first order approximation to the response surface and with bounds placed on the input parameters. The first two calibrations using the …

Statistical Process Control And Medical Surveillance. An Application With Liver Function Tests, Bryan D. Richardson

Theses and Dissertations

Traditionally, medical surveillance of liver disease generally involves a battery of tests. This research used multivariate analysis techniques to reduce the number of measures required to identify liver dysfunction and found using a Transferase Index (a combination of three tests; ALT, AST, and GGT) provided the most satisfying assessment, but the single best indicator, ALT, may be sufficient. Transferase Index and ALT criterion were both applied to SPC control charts. Through the use of statistical process control (SPC), this research identified work zones possessing signs of adverse effects to an individual's liver as a possible result of their work environment …

Optimization Analysis For Design And Planning Of Multi-Project Programs, Victor D. Wiley

Theses and Dissertations

Program Management concerns the long-term planning, coordination, and control of major technological, engineering, scientific, and/or developmental activities. In general, programs tend to be exceptionally large, consisting of several parallel or sequential projects or groups of projects. While many of the approaches developed for projects have been used in program management, there are critical differences between programs and projects. A key difference is the magnitude of programs, both in program duration and number of tasks to be coordinated. In addition, project parameters are driven by program decisions. While a large number of modeling efforts have focused at the project level, very …

A Methodology To Assess The Air Force Materiel Command's Exercise Support Program's Weighting Scheme, Gilbert D. Ness

Theses and Dissertations

This research performs analysis on the Air Force Materiel Command's Exercise Support Program's Weighting Scheme so that decision makers can create a more efficient and effective Resource Allocation - Integrated Process Team (RA-IPT) manpower allocation process. A linear programming (LP) model was derived from the Exercise Support Program (ESP) to assign manpower reductions throughout the Mission Element Board (MEB) organizational level in AFMC. Parametric analysis was performed on the LP model by simultaneously changing multiple objective function coefficients with the use of various direction vectors. These direction vectors were applied with the use of an incrementally increasing scalar step size …

Statistical Process Control In Medical Surveillance. An Application Using Spirometry, Paul W. Mcaree

Theses and Dissertations

This research effort concentrated on applying statistical process control techniques to the results of seven years worth of spirometry exams of workers at Wright-Patterson AFB in helping the occupational health squadron identify potential work hazard areas. Each spirometry exam was classified as abnormal or normal based on a comparison with established normals or a significant loss of function from the previous year's exam for the individual. Each test was classified into the work area of the individual and the number of abnormalities per population of the work area was examined.

Modeling Of Progressive Damage In Fiber-Reinforced Ceramic Matrix Composites, James P. Solti

Theses and Dissertations

An analytic methodology is developed to model the response of fiber-reinforced ceramic matrix composites (CMOs) when subjected to monotonic and fatigue loadings. The analysis requires the formulation of (1) a micromechanics model which defines the laminate's geometry and constitutive relationship; (2) failure criteria which estimate the extent of microstructural damage, and, finally, (3) a means of analyzing frictional slip, fiber pull-out, interfacial wear and laminate failure. For the present study, the behavior of unidirectional and crossply CMOs is investigated using modified shear-lag theory in conjunction with a set of failure criteria with a minimum reliance on empirical data. The damage …

An Investigation Into The Effects Of Lateral Aerodynamic Asymmetries, Lateral Weight Asymmetries, And Differential Stabilator Bias On The F-15 Directional Flight Characteristics At High Angles Of Attack, David R. Evans

Theses and Dissertations

The F-15 is a stable aircraft throughout most of its flight envelope. However, it still exhibits an uncommanded yawing and rolling tendency at high angles-of-attack. Identified influencing factors of this uncommanded motion are lateral aerodynamic asymmetries, lateral weight asymmetries, and differential stabilator bias. Previous research into the effects of these influencing factors has been qualitative. This thesis quantifies the effects and then identifies a symmetric F-15 configuration. The quantifying metric presented is net yaw acceleration. This thesis used both computer simulation and experimental flight test to quantify these effects. A discussion of each influencing factors effects on the F-15B high …

International Space Station Traffic Modeling And Simulation, Jillene B. Rylaarsdam

Theses and Dissertations

In an effort to provide NASA with an alternative perspective and some insights to the operational planning of the International Space Station (ISS), this research developed a simulation environment for the ISS and devised a method to evaluate various altitude strategies. The simulation environment allowed us to incorporate the natural random behaviors which affect the lifetime of objects in low earth orbit. We created prototype models of the operational planning process to analyze current altitude strategy approaches and acquire new strategies from insights observed. In addition, by extrapolating random future solar activity values from the interpolation of historical data, we …

Performance Study Of Shared Versus Nonshared Bandwidth On A Packet-Switched Network, John P. Stevens

Theses and Dissertations

In wide area computer data communications, many networks have evolved by satisfying increased user demands in the most expedient manner. In some cases, new users’ demands are satisfied by installing a new link, rather than sharing the links that are already in place. This research investigates the differences in performance between using a dedicated link for each source destination pair (nonshared bandwidth) and using a single link to be used by all source destination pairs (shared bandwidth). Simulation models are developed for a wide area network using shared bandwidth, and a wide area network using nonshared bandwidth. The quality of …

Development Of A Decision Support System For The Department Of Energy's Selection Of Waste Site Remediation Technologies, Brian E. Ralston

Theses and Dissertations

The Department of Energy is faced with the complex decision of selecting technologies for waste site remediation. This research focused on developing a decision support system to aid the decision maker in selecting the best strategy of remediation technologies. A decision analysis model was developed which incorporates life cycle cost data, risk information, and user input, to analyze the technology choices. The research outlined the use of multiple attribute utility theory using exponential attribute utility functions with a simple additive objective function. The best available data was used to demonstrate the capabilities of the model. The model provides the decision …

Measuring The Impact Of Programmed Depot Maintenance Funding Shortfalls On Weapon System Availability, Donald F. Hurry

Theses and Dissertations

This study used the Poisson regression technique, bootstrap estimates, and the Kaplan-Meier estimates for survivor curves to determine the impact of Programmed Depot Maintenance (PDM) on weapon system availability. More specifically, these techniques estimated the effect in the number failures per year due to PDM, but the bootstrap technique also estimated the effect in the amount of downtime experienced by a weapon system due to PDM. Although the Poisson regression model did not pass the rigors of statistical testing, the Poisson regression suggested differences in the number of failures per year between PDM and no-PDM weapon systems. The results of …

An Investigation Of Preliminary Feature Screening Using Signal-To-Noise Ratios, David B. Sumrell

Theses and Dissertations

A new saliency metric and a new saliency screening method are developed. This new metric, the SN saliency metric, is based upon signal-to-noise ratios, where the signal is provided by a sum of squared weights associated with a given feature, and the noise is based upon a sum of squared weights associated with a reference noise feature which is injected into the data. The resultant metric allows for a direct comparison of the feature of interest with a reference noise feature which is known to be nonsalient. The SN saliency screening method, which uses the SN saliency metric, offers the …

Applying Response Surface Methodology To Readiness-Based Leveling Of Reparable Items, Todd E. May

Theses and Dissertations

Reparable items play a large role in determining the readiness of United States Air Force weapon systems. Many factors characterizing flying tempo and item repair and transit time influence the level of fleet readiness. Readiness-Based Leveling (RBL) considers these factors as it seeks to maximize aircraft readiness as it allocates spare reparable items between bases and a depot. The purpose of this research was to demonstrate the validity of using response surface methodology (RSM) within the context of RBL in an effort to quantify the influences these factors have on aircraft readiness. RSM applied designed experiments and least squares regressions …

Surveillance Plan For Monitoring The Shelf-Life Of Chemical Defense Coveralls, Robert E. Neher Jr.

Theses and Dissertations

This thesis found a surveillance plan to be used to monitor the shelf-life of the Air Force's chemical defense coveralls. The sampling tests are destructive and the objective was to find a surveillance plan that would minimize the number of suits sampled yet provide enough information to accurately determine if the chemical defense coveralls had degraded past a minimum acceptable level. Six sampling plans were developed and analyzed. The sampling plans included the Air Force's original fixed sampling plan, several variations of sequential sampling plans, a Bayesian sampling plan, and an ad hoc pre-posturing plan. Each of the sampling plans …

Estimating Risks In Emerging Soil Remediation Technologies, Thomas J. Timmerman

Theses and Dissertations

The Department of Energy is focusing a long-term development effort on producing cheaper, safer, and faster state-of-the-art soil remediation technologies. To assist with the management of these innovative technology development projects, ways of quantifiably measuring technical risk were investigated through a detailed literature review. 'Technical risk' was defined in this study as the combination of the consequences of undesired events and their likelihood. Careful design of the inputs into a technology selection decision support system accounted for the uncertainty in forecasting final characteristics of remediation technologies still in the early phases of R&D. Experts made subjective probability estimates of these …

Procedures For Testing Deterministic Scheduling Models: A Dakota Case Study, Keith H. Mccready

Theses and Dissertations

The DAKOTA scheduling system has been proposed for use in the United States Air Forces Europe's (USAFE's) Operational Support Airlift (OSA) scheduling. This thesis examines the OSA scheduling topic and reviews the relevant literature on vehicle routing, concluding that exact methods are intractable for large problem sizes. Consequently, heuristic methods must be considered. This thesis takes a detailed look at the DAKOTA heuristic. It examines the concepts of Validation, Verification and Accreditation (VV&A), particularly as they apply to heuristics and algorithms. It then defines what measures of performance may prove useful in judging heuristics and algorithms in general, and details …

Nonlinearities In The Base Emitter Junction Of Heterojunction Bipolar Transistors, Oliver Woywode

Dissertations and Theses

The nonlinear behaviour of the base emitter junction in HBTs is investigated. Nonlinearities cause troublesome distortion and intermodulation of signals and raise the bit error rate. They are therefore a key issue in microwave communication systems. Hewlett-Packard's Microwave Design System (MDS) software package has been used to simulate these phenomena. The simulation results are verified by an analytical method called nonlinear current method which is a derivative of the Volterra series approach. With the aid of this method new analytical expressions are derived that provide insight into the subtleties of nonlinear phenomena. These expressions are evaluated by the program MAPLE …

The Discrete Laguerre Transform: Derivation And Applications, Giridhar Dhati Mandyam

Electrical and Computer Engineering ETDs

The discrete Laguerre transform (DLT) belongs to the family of unitary transforms known as Gauss-Jacobi transforms. Using classical methodology, the DLT is derived from the orthonormal set of Laguerre functions. Moreover, using recursion relationships common to all sets of orthonormal polynomials, generalized systolic arrays for forward and inverse unitary transform operations are derived and applied to the DLT. By examining the basis vectors of the transform matrix, the types of signals that can be best represented by the DLT are determined, namely oscillatory and damped oscillatory signals. Applications are demonstrated in the area of frequency domain adaptive filters, where the …

Riblet Effects On Gortler Vortex Development Over A Concave Surface, James A. Rothenflue

Theses and Dissertations

Riblet effects on Goertler vortex development in laminar and transitional flows were measured using three-dimensional laser-Doppler anemometry. Three freestream velocities were tested such that riblet spacing corresponded to Goertler vortex (GV) wavelengths which presumably would be either strongly amplified, weakly amplified, or attenuated by centrifugal forces on a curved surface. Experiments revealed the development of paired, counterrotating vortices within the riblet valleys over both flat and concave surfaces. For riblet spacings equivalent to weakly or non-amplified GV wavelengths, GV development on a curved surface was above the riblets and was delayed by the addition of riblets. The GV wavelength was …

On The Adaptive Multi-Stage Detector For Cancellation Of Multiuser Interference In Cdma Wireless Communication Systems, Nadir Sezgin

Dissertations

The classical multiple access techniques such as Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) schemes are band limited in terms of their capacity to be used for mobile radio communication. Recent developments in the area of digital signal processing, makes Code Division Multiple Access (CDMA) as a possible solution to the demand of capacity for the mobile radio communication. The capacity of CDMA is limited by multiuser interference, that is the interference from the other users.

The goal of this dissertation is to improve the multiuser CDMA detector with high Bit Error Rate (BER) performance, low …

Real Time Control Of Nonlinear Dynamic Systems Using Neuro-Fuzzy Controllers, Amitava Jana

Dissertations

The problem of real time control of a nonlinear dynamic system using intelligent control techniques is considered. The current trend is to incorporate neural networks and fuzzy logic into adaptive control strategies. The focus of this work is to investigate the current neuro-fuzzy approaches from literature and adapt them for a specific application. In order to achieve this objective, an experimental nonlinear dynamic system is considered. The motivation for this comes from the desire to solve practical problems and to create a test-bed which can be used to test various control strategies. The nonlinear dynamic system considered here is an …