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

Engineering Commons™

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

Theses and Dissertations

Discipline
Institution
Keyword
Publication Year

Articles 10471 - 10500 of 11503

Full-Text Articles in Engineering

A Methodology For Evaluating Military Systems In A Counterproliferation Role, Stanley Stafira Jr. Mar 1995

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 …

Go to article

The Development Of A Metamodel For A Major Weapon System Cost Model, Paul W. Campbell Mar 1995

The Development Of A Metamodel For A Major Weapon System Cost Model, Paul W. Campbell

Theses and Dissertations

Cost estimation is an integral part of the procurement process of major weapon systems. Despite this essential role, the cost estimation process is able to provide the decision makers and analysts with a limited amount of insight. This is due to the complex nature of the cost models that typically contain 20-30 cost estimating relationships (CERs) and 50-100 variables. In an effort to provide the decision makers and analysts with additional insight to the cost estimate, this research demonstrates a methodology that will (1) identify the cost drivers of the cost model, ( 2) estimate the effects of these cost …

Go to article

Patient-Aircraft Forecasting For The Strategic Aeromedical Evacuation "Lift-Bed Process", Donald F. Kimminau Mar 1995

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. …

Go to article

Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman Mar 1995

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 …

Go to article

Right-Hand-Side Multidimensional Optimality Analysis Of A Large Scale Linear Program Using Metamodelling Techniques, Osman Iyde Mar 1995

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 …

Go to article

A Methodology To Generate Air Force Materiel Command Manpower Reduction Alternatives, Steven T. Bishop Mar 1995

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 …

Go to article

Modified Goodness-Of-Fit Tests For The Inverse Gaussian Distribution With Two Unknown Parameter, Huseyin Gunes Mar 1995

Modified Goodness-Of-Fit Tests For The Inverse Gaussian Distribution With Two Unknown Parameter, Huseyin Gunes

Theses and Dissertations

Modified Kolmogorov- Smirnov (KS), Anderson-Darling (AD), Cramer-von Mises (CV), Kupier (V), and Watson (W) goodness-of-fit tests are generated for the inverse Gaussian distribution with unknown parameters. The inverse Gaussian parameters are estimated by maximum likelihood estimation. A Monte Carlo simulation of 50,000 repetitions is used to generate critical values for sample sizes of 5 through 50 with an increment of five, sample sizes of 60 through 100 with an increment of 10, and 24 different values of the inverse Gaussian shape parameter. A 50,000-repetition Monte Carlo power study is carried out using data with sample sizes of 5 through 100 …

Go to article

Estimation Of The Captive-Carry Survival Function For The Advanced Medium Range Air-To-Air Missile (Amraam), David R. Denhard Mar 1995

Estimation Of The Captive-Carry Survival Function For The Advanced Medium Range Air-To-Air Missile (Amraam), David R. Denhard

Theses and Dissertations

This thesis considers the problem of estimating the survival function of an item (probability that the item functions for a time greater than a given time t) from sampling data subject to partial right censoring (a portion of the items in the sampling data have not yet been observed to fail). Specifically the thesis describes several parametric and non-parametric statistical models that can be used when the sampling data is subject to partial right censoring. These models are applied to the case of estimating the captive-carry survival function of the AIM-120A Advanced Medium Range Air-to-Air Missile (AMRAAM).

Go to article

Investigation Of Ground Target Detection Methods In Fully Polarimetric Wide Angle Synthetic Aperture Radar Images, Wayne B. Mclaggan Mar 1995

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 …

Go to article

A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard Mar 1995

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 …

Go to article

Analysis And Modeling Of An Airport Departure Process, Joseph E. Hebert Mar 1995

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 …

Go to article

Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers Mar 1995

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 …

Go to article

The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson Mar 1995

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 …

Go to article

Modeling Corps Artillery In A Theater Level Combat Model, Richard F. Bowyer Mar 1995

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 …

Go to article

A New Goodness-Of-Fit Test For The Gamma Distribution Based On Sample Spacings From Complete And Censored Samples, Huseyin Duman Mar 1995

A New Goodness-Of-Fit Test For The Gamma Distribution Based On Sample Spacings From Complete And Censored Samples, Huseyin Duman

Theses and Dissertations

This thesis studies a new goodness-of-fit test for the gamma distribution with known shape parameter. This test statistic, Z*, is based on spacings from complete or censored samples. The size of samples varied between 5 and 35. The critical value tables were generated for the Z* test statistic for complete and censored samples. The critical values were obtained for five different significance levels: 0.20 0.15, 0.10, 0.05, and 0.01. An extensive power study, containing 50,000 Monte Carlo runs was conducted using nine alternative distributions, Ha. It was observed that the Z* test statistic was more powerful against certain …

Go to article

Dynamic Maintenance Scheduling For A Stochastic Telecommunication Network: Determination Of Performance Factors, Todd S. Patterson Mar 1995

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 …

Go to article

An Analytical Framework For Assessing Future Force Structure Requirements Under Uncertainty, Michael L. Fredley Mar 1995

An Analytical Framework For Assessing Future Force Structure Requirements Under Uncertainty, Michael L. Fredley

Theses and Dissertations

The objective of this research was to develop an analytical framework to assess future force structure requirements under the major uncertainties inherent in the post-Cold War era. Among the uncertainties are the frequency and nature of future threats to U.S. interests and the cost of maintaining, building, and demobilizing forces. The centerpiece of the methodology is a computer model which simulates the development of threats to U.S. interests and the actions the U.S. takes to protect those interests. From this simulation, the costs and risks associated with different policy alternatives can be estimated. The simulation is set within a broader …

Go to article

A Methodology For Comparing The Value Of Competing Afmc Manpower Allocation Strategies, Sandra K. Smith Mar 1995

A Methodology For Comparing The Value Of Competing Afmc Manpower Allocation Strategies, Sandra K. Smith

Theses and Dissertations

This research effort develops a methodology for Air Force Materiel Command (AFMC) decision makers to use during mandated resource allocation exercises for comparing competing manpower allocation strategies. A value model is used to represent the hierarchical objectives of the command, with the primary objective being the attainment of maximum mission effectiveness in the face of constrained resources. Value model decomposition is patterned according to the command's organizational structure. Scoring functions derived using direct assessment survey techniques capture the relationship between manpower and mission effectiveness for lowest level organizations. An additive value function represents the model mathematically; the primary objective value …

Go to article

Multipoint Quadratic Approximation For Numerical Optimization, Michael A. Blaylock Mar 1995

Multipoint Quadratic Approximation For Numerical Optimization, Michael A. Blaylock

Theses and Dissertations

A quadratic approximation for nonlinear functions is developed in order to realize computational savings in solving numerical optimization problems. Function and gradient information accumulated from multiple design points during the iteration history is used in estimating the Hessian matrix. The approximate Hessian matrix is the available for a second order Taylor series approximation to the functions of interest. Several truss and frame models will be used to demonstrate the effectiveness of the new Multipoint Quadratic Approximation (MQA) in solving structural optimization problems.

Go to article

Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert Mar 1995

Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert

Theses and Dissertations

This study investigated an analytical means of selecting the quickening time constant for the standardized Heads-Up Display flight path marker. The theoretically determined time constant allowed a faster, less resource intensive means of selecting the quickening time constant. The theoretically best time constant for pilot-aircraft handling qualities was equal to the airframe pitch attitude high frequency zero time constant, Tθ2. Flight test indicated an empirical, more labor intensive method yielded better handling qualities, even though paper analysis indicated the theoretical method was better. The theoretically determined time constant gave slightly lower handling qualities. but was less costly to …

Go to article

Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes Jan 1995

Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes

Theses and Dissertations

The purpose of this thesis was to improve the process of modeling and analyzing ballistic vulnerability data. This was accomplished by addressing two of the more urgent needs of vulnerability analysts; the ability to display fault tree data and to edit target descriptions. A vulnerability data visualization program called VISAGE was modified to meet these needs. VISAGE was originally created to preview static shotline plots and subsequently grew into a full-featured visualization package for vulnerability target descriptions and analyses data. The next logical step in the programs evolution was to include the needed editing and fault tree display capabilities. The …

Go to article

Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis Jan 1995

Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis

Theses and Dissertations

This research developed a comprehensive description of the simulation environment of Architect, a domain-oriented application composition system being developed at the Air Force Institute of Technology to explore new software engineering technologies. The description combines information from several previous research efforts and Architect's source code into a single, comprehensive document. A critical evaluation of the simulation environment was also performed, identifying improvements and modifications that enhance Architecture's application execution capabilities by reducing complexity and execution time. The analysis was then taken one step further and presented extensions to the current simulation environment. The extensions included investigating the feasibility of mixed-mode …

Go to article

Study Of The Time Efficiency And Volume Of Wood Used For Three Types Of Stove In The Salitrón Community Of San Juan Ermita, Department Of Chiquimula, Fredy Samuel Coronado López Jan 1995

Study Of The Time Efficiency And Volume Of Wood Used For Three Types Of Stove In The Salitrón Community Of San Juan Ermita, Department Of Chiquimula, Fredy Samuel Coronado López

Theses and Dissertations

In developing countries such as Guatemala, firewood is increasingly being used for cooking in most rural areas. Consequently, there is a shortage of firewood in these areas beca use trees do not grow at the same rate as they are consumed. Some authors report that 90% of the heat from firewood is lost during combustion. Several alternatives to open pit fires exist to reduce the amount of firewood used. However, these alternatives need to be evaluated to determine their efficiency. This project compared the time efficiency and volume of firewood used in the Finlandia style improved stoves, Josefina stoves, and …

Go to article

Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis Dec 1994

Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis

Theses and Dissertations

The Mission Route Planning (MRP) Problem falls into the general class of multicriteria path search problems. Multiple criteria are evaluated to select an optimal aircraft mission route through a hostile environment. Criteria for distance travelled and radar exposure are combined into a single cost function for route evaluation. Radar calculations are performed dynamically. The A* search algorithm is applied to the MRP problem, and a parallel implementation is developed and tested. A unique combination of distributed OPEN lists with a global CLOSED list strategy produced fast execution times on the Paragon. Test cases for scenarios with 15 radars took less …

Go to article

Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter Dec 1994

Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter

Theses and Dissertations

Mean flow and compressible turbulence measurements have been obtained upstream and within a shock boundary interaction and a compression ramp in Mach 3 flow. Compressible turbulence models have met with little success in the accurate prediction of high-speed flows involving complicated shock boundary interactions and adverse pressure gradients because of a crucial lack of experimental data. Data were collected using conventional Pitot and cone static probes, single overheat cross-wire anemometry, multiple overheat cross-wire anemometry, and flow visualization techniques. Direct measurements of the total Reynolds shear stress were obtained using a turbulence transformation. Results indicate that compressibility effects, as evidenced by …

Go to article

Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey Dec 1994

Investigation Into The Behavior Of Geometrically Nonlinear Composite Arches, John C. Bailey

Theses and Dissertations

This research modifies the existing finite element formulation of a potential energy based large deformation and moderate rotation theory. Hermitian shape functions replace the existing linear bending angle interpolations. Negligible differences between the two formulations indicate the underlying kinematics limit the accuracy, not the finite element interpolations. Using the new program, numerous nonlinear arch geometries are modeled to investigate the effects of arc length and thickness variations. Local and global snapping phenomena are captured as well as through the thickness shear driven nonlinearities.

Go to article

Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker Dec 1994

Flight Control Design Using Mixed H2/Μ Optimization, Douglas D. Decker

Theses and Dissertations

This thesis examines the use of the mixed H2-Microns optimal control synthesis method in the design of a flight control system for the lateral-directional axes of the F-16 Variable Stability In-Flight Simulator Test Aircraft (VISTA). The method is designed to minimize the H2 norm (two-norm) for a given value of microns. This should provide adequate noise and disturbance rejection while maintaining robustness against several types of uncertainties in the system. This thesis finds that, for this problem, the two-norm is not an accurate representation of the outputs of interest. When the two-norm is broken up into its constituent parts an …

Go to article

The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter Dec 1994

The Effects Of Transverse Vibration On The Performance Of An Axial Groove Wick Heat Pipe, Kenneth A. Carpenter

Theses and Dissertations

An experimental investigation was performed to determine the effects of transverse vibrations on the performance of an ammonia-aluminum axial groove wick heat pipe. Theoretical calculations predicted a performance degradation due to the working fluid being shaken out of the upper capillary grooves. A benchtop shaker was used to apply transverse, sinusoidal vibrations of 30, 35, and 40 Hertz, corresponding to peak acceleration amplitudes of 1.84g, 2.50g, and 3.27g, respectively. Maximum heat throughput, Q sub max, of the vibrating heat pipe was measured. A comparison of these values and static Q sub max values indicated a degradation in heat pipe performance. …

Go to article

Effects Of Blowing Ratio On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Joseph L. Lenertz Dec 1994

Effects Of Blowing Ratio On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Joseph L. Lenertz

Theses and Dissertations

This experiment analyzed the effects of blowing ratio on heat transfer to the throat region of a porous-walled nozzle, using the AFIT low speed shock tube. Heat flux data were taken from both sides of a two-dimensional Mach 2.0 Re-m=5.2x107 nozzle using thin film resistance thermometers. One side was transpiration-cooled by secondary air injection through a sintered wall, while the other side served as a control. Control results were validated using empirical relations, and cooled side results showed up to a 14% reduction in heat transfer coefficient at blowing ratios of only 0.51%. The linear nature of cooling effectiveness …

Go to article

Investigation Of Boundary Layer And Performance Effects Of Transpiration Cooling Through A Porous Plate In A Rocket Nozzle, David N. Keener Dec 1994

Investigation Of Boundary Layer And Performance Effects Of Transpiration Cooling Through A Porous Plate In A Rocket Nozzle, David N. Keener

Theses and Dissertations

This study used a range of low blowing ratios with air through an area of porous material in a Mach 2.0 nozzle to quantity the change in boundary layer thickness as a function of blowing ratio. Also, exit and wall Mach number profiles at each blowing ratio were collected to characterize performance losses as a result of blowing. Performance in terms of specific impulse was also studied. As expected, the boundary layer thickness increased and nozzle performance in terms of exit Mach number decreased with increasing blowing ratio.

Go to article

First Prev Next Last