Engineering Commons^™

Wing-Section Optimization For Supersonic Viscous Flow, Cem Cihan Item

Mechanical & Aerospace Engineering Theses & Dissertations

The recent interest in the High Speed Civil Transport (HSCT) has resulted in renewed research studies of optimized supersonic cruise transport configurations. Incorporation of flow viscosity effects in the design process of such a supersonic wing is currently under investigation. This may lead to more accurate problem formulations and, in tum, greater aerodynamic efficiency than can be obtained by the traditional, inviscid, linear theories. In this context, for a design code to be a candidate for a complex optimization problem, such as three-dimensional viscous supersonic wing design, it should be validated using simpler building-block shapes.

To optimize the shape of …

Open-Loop State-Space Model Identification From Closed-Loop Data, Lori Guy

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis provides an investigation of a system identification algorithm which identifies an open-loop state-space model from a linear system that is operating under closed-loop conditions. In order to investigate the system identification algorithm some basic ideas of system identification theory are reviewed. Examples using simulated data are presented to characterize the effects of varying the parameters for open-loop and closed-loop system identification processes. Both noise· free and noise contaminated cases are simulated. Linear Quadratic Gaussian (LQG) control theory is reviewed and the motivation for using iterative LQG control feedback is discussed. The derivation of the proposed system identification algorithm …

Fetal Heart Rate Detection With A Passive Acoustic Sensor System, Zongyao Zhou

Electrical & Computer Engineering Theses & Dissertations

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones from noise contaminated signals obtained from passive acoustic sensors. A nonlinear Teager energy operator is utilized for detection of the fetal heart tone event. Autocorrelation and a parallel redundancy correction algorithm derives fetal heart rates. A real time monitoring system is described which records and plots the time history of both the fetal heart rate and the acoustic fetal heart signal. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a …

Thermal Effects On Y2O3:Eu3+ For Fiber Optic Temperature Sensing, Arnel C. Lavarias

Electrical & Computer Engineering Theses & Dissertations

Fiber optic methods have gained acceptance in the past several years as non­ intrusive optical techniques of measuring environmental variables, particularly under hostile conditions. Fiber optic temperature sensors are required for many applications which have a large operating range. One way to implement this sensor is to introduce rare earth-doped materials into a fiber showing temperature-dependent optical emission characteristics. The thermal effects on optical emission characteristics of Y₂O₃:Eu³⁺ were studied. The thermal broadening and temperature dependence of the lifetime (τ) of the 611.4 nm emission due to the ⁵D₀ ➔ 7F …

Generalization Metrics For Neural Modeling Applications In System Identification, Denise M. Reeves

Electrical & Computer Engineering Theses & Dissertations

In this thesis a procedure to design multilayer feedforward networks for system identification with good prediction properties is presented. Central to the design procedure is a means to characterize the prediction capabilities of various trained neural networks. Such knowledge will allow for the identification of the best network design. For system identification purposes, a "good" model is one that is good at predicting, In particular, a good model is one that produces small prediction errors when applied to a set of cross-validation data. We formulate and implement a criterion function designed to measure the size of a trained neural network's …

Development Of A Knowledge-Based System For Generating Process Plans Using Group Technology: A Study For Norfolk Naval Shipyard, William P. Keene Jr.

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this research was to study and analyze the Norfolk Naval Shipyard's manufacturing methods of determining part families and generating part process plans for parts in the machine shop. A knowledge-based decision support system was designed based on knowledge acquired from machinist experts and documented sources of the Norfolk Naval Shipyard. The system interprets specific part information provided by the user, categorizes parts into part families and generates process plans to manufacture the parts. The system was evaluated and tested for parts provided by Norfolk Naval Shipyard.

Predicting Utility Bills For Air Combat Command A Study Of Forecasting Techniques, William L. Luthie

Engineering Management & Systems Engineering Theses & Dissertations

Many companies use forecasting techniques as a tool in managing their assets. Trends in such items as sales, population and inventory levels have all been determined at one time or another using forecasting, yet research indicates that these tools have not been utilized to predict utility budgets. This research was conducted to determine if such techniques could be applied to the specific task of predicting the utility bill at an Air Force base. Three quantitative models were chosen, the Moving Average, Exponential Smoothing and Regression, to determine their applicability to the task at hand. One base within Air Combat Command, …

Component Mode Synthesis-Based Design Methodology For Structural Modification And Synthesis, Venkateshwarlu Maroju

Mechanical & Aerospace Engineering Theses & Dissertations

In this work, structural modification and synthesis techniques based on component mode synthesis are presented. The component mode synthesis method formulates the eigenvalue equation of an entire structure in terms of the vibration characteristics of individual components in the assembly. Through this functional relationship, the individual components are successfully treated as the design entities in the proposed methodology. Unlike conventional design modification techniques that can only treat the properties of the finite elements as the design variables, this technique uses the vibration and static responses of the individual components as the design entities. The sensitivity derivatives of the global responses …

Automatic Differentiation For First- And Second-Order Sensitivity Derivatives Of A Cfd Code, Laura Lee Sherman

Mechanical & Aerospace Engineering Theses & Dissertations

The straightforward automatic-differentiation and the hand-differentiated incremental iterative methods are interwoven to produce a hybrid scheme that captures some of the strengths of each strategy. With this compromise, discrete aerodynamic sensitivity derivatives are calculated with the efficient incremental iterative solution algorithm of the original flow code. Moreover, the principal advantage of automatic differentiation is retained (i.e., all complicated source code for the derivative calculations is constructed quickly with accuracy). The basic equations for second-order sensitivity derivatives are presented; four methods are compared. Each scheme requires that large systems are solved first for the first-order derivatives and, in all but one …

Non-Linear Boundary-Layer Receptivity Due To Distributed Surface Roughness, Tahani R. Amer

Mechanical & Aerospace Engineering Theses & Dissertations

The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting mode shapes due to surface roughness receptivity have also been determined, analyzed, and shown to be in agreement with theory and other experimental work. It has been shown that there is a linear relationship between the surface roughness and receptivity for certain roughness configurations …

Modeling And Simulation Of Load Introduction For Fuselage Crown Panel Testing, Kevin P. Belack

Mechanical & Aerospace Engineering Theses & Dissertations

This paper discusses the mechanism and behavior of load introduction to internally pressurized fuselage crown panels. Emphasis is placed on the finite element modeling of a simulated pressure-box test machine and representative fuselage crown panel. The geometry and mesh requirements for the finite element model are examined through numerical studies which gradually increase in complexity. These numerical studies culminate in the detailed specification of boundary conditions, mesh densities, load introduction mechanisms, element choice and solution process for the simulation of a pressure-box test machine and test panel.

The results obtained using the finite element model are then compared with experimental …

Identification And Characterization Of The Iron-Zinc Intermetallics Formed In Galvanneal Steel, Richard Frederick George Grant

Physics Theses & Dissertations

The demand to improve the corrosion resistance of steel sheet, particularly for use within the automotive industry, has led to a dramatic increase in the use of coated steels in place of cold-rolled sheet steel. Galvanneal steel results from the post annealing of the zinc-coated steel sheet, in which iron and zinc are interdiffused to form an iron-zinc alloy coating. Within this alloy coating, four main iron-zinc phases, Zeta, Delta, Gamma-1, and Gamma may be present. Manufacture of the most suitable coating requires identifying which phases form during the galvannealing process, an understanding of the properties of each phase and …

Automatic Synthesis Of Vlsi Layout For Analog Continuous-Time Filters, David Lyle Robinson

Dissertations and Theses

Automatic synthesis of digital VLSI layout has been available for many years. It has become a necessary part of the design industry as the window of time from conception to production shrinks with ever increasing competition. However, automatic synthesis of analog VLSI layout remains rare.

With digital circuits, there is often room for signal drift. In a digital circuit, a signal can drift within a range before hitting the threshold which triggers a change in logic state. The effect of parasitic capacitances for the most part, hinders the timing margins of the signal, but not its functionality. The logic functionality …

Flight-Deck Automation: The Attitudes And Perceptions Of Selected Boeing 757/767 Air Carrier Pilots, William Woodrow Clark

Master's Theses - Daytona Beach

Development in electronic displays and computers have enabled avionics designers to present the pilot with ever increasing amounts of information in greater detail and with more accuracy- However, technological developments have not always brought about enhancement of the pilot's role. Investigating the interaction of cockpit crew members and the vast array of automated systems they control and monitor will contribute to the determination the effect this interface has on the performance of the cockpit team. This study utilized a questionnaire to determine if the opinions of the flight crew suggested performance is impacted negatively by automation. There was no significant …

Nonlinear Analysis Of Composite Beams Under Random Excitations, Snorri Gudmundsson

Master's Theses - Daytona Beach

The vibration responses of three unsymmetrically laminated beams, that are excited with a Gaussian random forcing function, are studied in this thesis. The beams are analyzed nonlinearly and compared to linear results, indicating some important corrections. The solution procedure begins with the derivation of the general equation of motion using Galerkin's method. Then, two approaches are taken in the solution. First, the equation of motion is attacked directly employing a real time Runge-Kutta numerical analysis. Second, the method of equivalent linearization is used. The thesis finds the results from the two approaches to be in a close agreement, although some …

The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson

Theses and Dissertations

This study investigated the effect on simulation output of repeatedly sampling an embedded metamodel. A metamodel is said to be embedded within a simulation if it is used to replace a submodule of that simulation. Replacing a deterministic module with an embedded deterministic metamodel poses no apparent mathematical problems. However, using a deterministic metamodel to replace a stochastic simulation component could require additional corrective actions. This research was performed in two phases. The first phase dealt with a set of tandem queues. It was shown that as each queue was sequentially replaced with a metamodel, the total system variance was …

Dynamic Maintenance Scheduling For A Stochastic Telecommunication Network: Determination Of Performance Factors, Todd S. Patterson

Theses and Dissertations

This research proposes an analytical approach to access the relationship between maintenance facility location and communication network performance measurement using a selected dynamic maintenance scheduling protocol. There were three objectives established for this effort. The first objective was the determination of an upper-bound upon the level of performance for a telecommunication network using dynamically scheduled maintenance to evaluate maintenance depot location. This was achieved by using a two-stage algorithm, first locate a maintenance depot by using stochastic algorithms, and then to measure the resulting impact upon performance with a multi-commodity network flow model. The second objective was to develop the …

Applications Of Statistical Process Control In Monitoring Aircrew Bombing Proficiency, Kirk G. Horton

Theses and Dissertations

The current tools used by squadron supervisors to monitor the bombing performance of aircrews flying F-111E aircraft are monthly reports that have little predictive capability. No real-time methodology exists for monitoring and predicting aircrew bombing performance and preventing bombing problems that might cause an individual to become unqualified. It has been suggested that Statistical process Control (SPC) can be applied to the bombing process to develop tools for managing the process, correcting problems, and improve the bombing performance of a squadron. This study investigates the application of SPC to the bombing process. It examines data taken from an F-111E Fighter …

Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman

Theses and Dissertations

This thesis examined the use of response surface methodology (RSM) to estimate the parameters of a finite-element groundwater model. An existing two-dimensional, steady-state flow model of a fractured carbonate groundwater system in southwestern Ohio served as the calibration target data set. A Plackett-Burman screening design showed that only four of the ten hydraulic conductivity zones significantly contributed to the output of the finite-element model. Also, the effective porosity parameter did not significantly affect the model's output. Using only the four significant hydraulic conductivity parameters; four two-level, four-factor designed experiments were conducted to exploit the first-order response surface defined by a …

Right-Hand-Side Multidimensional Optimality Analysis Of A Large Scale Linear Program Using Metamodelling Techniques, Osman Iyde

Theses and Dissertations

A methodology for optimality analysis of linear programs was developed by Johnson, Bauer, Moore, and Grant to create metamodels using response surface methodology techniques such as experimental design and least squares regression, and a geostatistical estimation technique, namely kriging. Metamodels have the form of a simple polynomial, and they predict the optimal objective function value of an LP for various levels of the constraints. They eliminate the necessity of determining which critical region contains the right-hand-side (RHS) vector of interest since they are valid over multiple critical regions. The methodology of Johnson, et al. can be applied to large scale …

Selecting Optimal Experiments For Feedforward Multilayer Perceptrons, Lisa M. Belue

Theses and Dissertations

Where should a researcher conduct experiments to provide training data for a multilayer perceptron? This question is investigated and a statistically-based method for optimally selecting experimental design points for multilayer perceptrons is introduced. Specifically, a criterion is developed based on the size of an estimated confidence ellipsoid for the weights in the multilayer perceptron. This criterion is minimized over a set of exemplars to find optimal design points. Initially, single output networks are examined. An example is used to demonstrate the superiority of optimally selected design points over randomly chosen points and points chosen in a grid pattern. Also, two …

Investigation Of Ground Target Detection Methods In Fully Polarimetric Wide Angle Synthetic Aperture Radar Images, Wayne B. Mclaggan

Theses and Dissertations

Target detection is a high priority of the Air Force for the purpose of reconnaissance and bombardment. This research investigates and develops methods to distinguish ground targets from clutter (i.e. foliage, landscape etc.) in Wide Angle Synthetic Aperture Radar (WASAR) images. WASAR uses multiple aspect angle SAR images of the same target scene. The WASAR data was generated from a pre-release software package (XPATCH-ES) provided by the sponsor (WL-AARA). A statistical analysis and feature extraction is performed on the XPATCH-ES data. Polarimetric and wide angle covariance matrices are estimated and analyzed. From an analysis of the wide angle covariance matrix …

A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard

Theses and Dissertations

Environmental managers must compare the potential impacts of waste products when deciding upon courses of action. The estimation and comparison of these impacts is a subjective process, and few methods of comprehensive, quantitative comparison of waste products currently exist. The intent of this study is to develop a decision methodology to evaluate the environmental impacts of waste products and to score them for comparison. The method will follow established system design principles and incorporate significant characteristics of the waste material. Scores derived to represent the environmental impacts of materials will then he analyzed employing statistical and probabilistic methods to assess …

Analysis And Modeling Of An Airport Departure Process, Joseph E. Hebert

Theses and Dissertations

This study analyzes departure delays at a major airport using probability models to represent this non-homogeneous process. The models developed in this study expand on the Markovian models presently used by employing the method of stages to represent some of the model processes. This technique improves the user's ability to achieve a close fit for the service time probability distribution while maintaining the advantages of the Markovian model. The three types of models developed and compared all assume a Markovian system entry process. The first model uses an exponential distribution to model the service process. The second uses an Erlang …

Life-Cycle Cost Analysis For Radioactive Waste Remediation Alternatives, Thomas P. White, Ronald J. Toland, Dorian Y. Buitrago

Theses and Dissertations

This research has two primary objectives. The first is to develop a generic, interactive, spreadsheet-based life-cycle cost model that uses net present value and risk analysis techniques for cost comparison. The second is to apply the model specifically to the vitrification and cementation methods of waste remediation. By using spreadsheet analysis and graphics capabilities, the model will provide direct and objective comparisons of remediation alternatives. Since vitrification is a new technology, the plant design and operations are conceptual. Therefore, computer simulation and engineering judgement are integral to the vitrification LCC estimate.

Patient-Aircraft Forecasting For The Strategic Aeromedical Evacuation "Lift-Bed Process", Donald F. Kimminau

Theses and Dissertations

The goal of this research is to develop a tool for the Global Patient Movement Requirements Center (GPMRC) to efficiently forecast Aeromedical Evacuation (AE) aircraft and schedule patients in the lift-bed process. During a contingency, GPMRC is responsible for requesting required airlift, and providing lift-bed candidates to the Theater Patient Movement Requirements Center. The objective is to evacuate all waiting patients while minimizing the number of C-141 aircraft which must be dedicated to the AE mission. In the solution process, a short-term forecast of patient movement requirements is input, including number of patients, bed and aircraft availability, and hub preferences. …

Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers

Theses and Dissertations

The purpose of this study is to evaluate response surface methodology as a sensitivity analysis tool in the area of decision analysis. The advent of low-cost personal computer software, such as DPLTM, has created an accessible tool with the ability to frame and solve influence diagrams for decision problems. This study provides a comparison of current sensitivity analysis techniques vs those made possible through response surface methodology (RSM). Sensitivity analysis alternatives are demonstrated on a decision problem concerning the evaluation of force structure options for the Department of Defense. Sensitivity analysis is performed on both one-way and two-way perturbations of …

A Methodology For Evaluating Military Systems In A Counterproliferation Role, Stanley Stafira Jr.

Theses and Dissertations

This thesis develops a methodology to evaluate how dissimilar military systems support the accomplishment of the United States? counterproliferation objectives. The overall scope is to develop a model of the counterproliferation decision process that enables systems to be evaluated against common criteria. By using decision analysis, an influence diagram model is developed which represents military activities in the counterproliferation process. The key questions which must be asked in evaluating counterproliferation systems are highlighted. An analysis of perfect intelligence, perfect defensive, and perfect offensive systems reveal that a perfect intelligence system provides the greatest potential to meet the United States' counterproliferation …

A Methodology To Generate Air Force Materiel Command Manpower Reduction Alternatives, Steven T. Bishop

Theses and Dissertations

The purpose of this study is to generate manpower authorization reduction alternatives for Air Force Materiel Command. The advent of low-cost personal computer software applications, such as Excel, has created an assessable tool with the ability to solve linear programming problems. This research examines the manpower resource reduction process of Air Force Materiel Command and models the Resources Allocation - Integrated Process Team (RA-IPT) decision process. A linear programming model is developed to assign these reduction through a weighted sum. The linear programming model is developed as a Microsoft Excel spreadsheet model, the Exercise Support Program (ESP), using Visual Basic …

Modeling Corps Artillery In A Theater Level Combat Model, Richard F. Bowyer

Theses and Dissertations

This thesis describes the development of a methodology to explicitly model corps artillery assets in the Joint Staff's Joint Stochastic Analysis Research (J-STOCHWAR) and to quantify Army doctrine that guides organization of artillery for combat. The methodology incorporates corps artillery into the J-STOCHWAR by using the five fundamentals for organizing for combat, which reflect Army doctrine, and combines them with basic concepts already used in existing theater-level models. Other aspects of the problem include determining the appropriate level of detail, identifying techniques to solve the problem, and verifying the results. The proposed decision analysis solution technique provides a feasible method …