Engineering Commons^™

Quantifying A Key Injection Molding Attribute Defect, Kristopher Bryan Horton

Masters Theses

A mounting demand for high quality, low cost plastic injection molded products brings with it goals such as low or even zero defects. In order to achieve these types of "world class" expectations, resources are used to monitor and control variable data such as cycle time, part weight or dimensions. Despite this emphasis on variable data, parts are often rejected based on attribute molding defects such as sink marks or splay that are measured by subjective criteria and therefore difficult to control. Appearance of a part once considered acceptable may no longer be, due to changing expectations or subjective interpretation …

Estimation Of Parameters For Calibration And Validation Of Monochlorobenzene Flux, Christina Hill

Electronic Dissertations and Theses

Research is currently being conducted to enhance the existing pump-and-treat remediation strategy at the Petro Processors, Incorporated site (PPI)-a petrochemical disposal site consisting of two locations in East Baton Rouge Parish (Louisiana). Monochlorobenzene, a biodegradation byproduct of hexaclorobenzene, is a toxic chemical prevalent at the site; the diffusivity of monochlorobenzene is being studied through desorption experiments. The objective of soil desorption experiments is to determine soil-water distribution or partition coefficients. Partitioning is the distribution of solutes between two phases such as solid phase and a liquid (aqueous) phase. The derivation of acceptable partition coefficients "are used in [models] to determine …

Analysis And Correctional Procedure For The Operation Of The Huntsville Botanical Garden Reciprocating Constructed Wetland, Amy Louisa Cunningham

Honors Capstone Projects and Theses

No abstract provided.

Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr

Theses and Dissertations

Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms …

Network Security Versus Network Connectivity: A Framework For Addressing The Issues Facing The Air Force Medical Community, Franklin E. Cunningham Jr.

Theses and Dissertations

The Air Force has instituted Barrier Reef to protect its networks. The Air Force medical community operates network connections that are incompatible with Barrier Reef. To overcome this problem, OASD(HA) directed the Tri-Service Management Program Office (TIMPO) to develop an architecture that protects all military health systems and allows them to link with all three services and outside partners. This research studied the underlying networking issues and formed a framework based on data from network experts from the Air Force's medical centers and their base network organizations. The findings were compared TIMPO and a composite framework was developed that more …

Power, Performance, And Perception (P3): Integrating Usability Metrics And Technology Acceptance Determinants To Validate A New Model For Predicting System Usage, Alan P. Fiorello

Theses and Dissertations

Currently, there are two distinct approaches to assist information technology managers in the successful implementation of office automation software. The first approach resides within the field of usability engineering, while the second approach is derived from the discipline of management information systems (MIS). However, neither approach has successfully produced conclusive evidence that explains what characteristics facilitate system use as well as influence user acceptance of the system. This study reports on the validity of a new model, entitled the Power, Performance, Perception (P3) model, that links the constructs of usability engineering to user acceptance. Additionally, speech recognition software (SRS) was …

Effects Of Foreign Object Damage From Small Hard Particles On The High-Cycle Fatigue Life Of Ti-6a1-4v, Joseph L. Hamrick Ii

Theses and Dissertations

Thin rectangular samples of Ti-6Al-4V were damaged by four methods to represent foreign object damage found in turbine engine blades: 1) impact with 2 mm and 5 mm diameter glass spheres at 305 m/s, 2) impact with 2 mm and 4 mm diameter steel spheres at 305 m/s, 3) quasi-static displacement controlled indentation using steel chisels with 1 mm, 2 mm and 5 mm diameter tips and 4) shearing notches with a 2 mm diameter chisel point under a quasi-static loading condition. Finite element analysis was used to study the relationship between the stress state created by the plastic damage …

Reverse Engineering Of Foreign Missiles Via Genetic Algorithm, Jon D. Wollam

Theses and Dissertations

One mission of the National Air Intelligence Center (NAIC) is the reverse engineering of foreign missile weapon systems from incomplete observational data. In the past, intuition and repeated runs of a missile performance model were required to converge to a solution compatible with observed flight characteristics. This approach can be cumbersome and time consuming, as well as being subject to undesirable influences from the analyst's preconceptions and biases. An alternative approach has been created to apply genetic algorithm (GA) techniques to allow automation of the process, wider exploration of the design space, and more optimal solutions matching the observational data. …

Electrical And Optical Characterization Of Intrinsic And Ion-Implantation Induced Defects In 6h- And 4h-Sic, Michael B. Scott

Theses and Dissertations

Deep level transient spectroscopy (DLTS), Hall effect, and cathodolummescence (CL) measurements are used to characterize the intrinsic and ion-implantation induced defects in high-temperature (475 and 500 °C) ion-implanted epitaxial n-type 6H- and 4H-SiC, ion-implanted with Cr, Mg, Ar, N, and P atoms. Comparison of room-temperature and high-temperature ion-implanted 6H-SiC:Mg and :Cr indicate the significance of high-temperature ion implantation on the activation of the ion-implanted atoms and damage-recovery of the crystalline lattice. The effects of high-temperature annealing on both damage-recovery and implanted ion activation are detected and analyzed, from 1200 to 1800 °C. Trap parameters of both damage-related and species-related defects …

Defining Virtual Interactions: A Taxonomy For Researchers And Practitioners, Glade G. Oxborrow

Theses and Dissertations

Many uses for virtual technology are being identified by diverse organizational entities around the world. Before these technologies can be fully utilized, it is important to have a common definition and understanding of what is meant by the term virtual. It is also important to understand the structural configurations possible using virtual technology and the types of virtual interactions that may occur using these technologies. This thesis will define the basic premises, structures, and definitions applicable to vial interactions. It also defines various types of virtual interactions that may occur using virtual technology. These designations will help both practitioners and …

Approximation And Optimization Of An Auditory Model For Realization In Vlsi Hardware, Samuel L. Sangregory

Theses and Dissertations

The Auditory Image Model (AIM) is a software tool set developed to functionally model the role of the ear in the human hearing process. AIM includes detailed filter equations for the major functional portions of the ear. Currently, AIM is run on a workstation and requires 10 to 100 times real-time to process audio information and produce an auditory image. An all-digital approximation of the AIM which is suitable for implementation in very large scale integrated circuits is presented. This document details the mathematical models of AIM and the approximations and optimizations used to simplify the filtering and signal processing …

Flight Testing Amateur-Built Helicopters, Jeffrey Scott Bender

Masters Theses

Test-flight procedures for the amateur-built helicopter are presented. Test methods were acquired from acceptable practices for flight testing Normal Category Rotorcraft, Amateur-Built Aircraft and Ultralights. These acceptable practices were modified to overcome the challenges faced by the amateur-built helicopter test pilot. These challenges include limited in-flight instrumentation. A significant modification of procedures was to establish a methodology of flight testing using collective control stick position as an indicator of power during performance testing. Additionally, this procedure provides a method structured to overcome limited instrumentation during testing of stability and control. In-flight test data of a United States Army OH-58 was …

Thermodynamic Model And The Controlling Variables Of Phosphate Lattice Loss, Mohammad Abutayeh

USF Tampa Graduate Theses and Dissertations

A thermodynamic model was developed based upon five equilibrium reactions to predict the limits of distribution of phosphates between the liquid and the solid phases in a reactor used to extract phosphoric acid from phosphate rock. A computer code was generated to carry out different simulations of the model using several inputs of temperatures and liquid phase sulfuric acid contents. Ideal Solution, Debye-Hückel, and Robinson-Guggenheim-Bates electrolyte activity coefficient models were employed alternately in each simulation to complete the thermodynamic model and the outputs were compared to one another.

Experimental data of equilibrium constants were regressed to adjust the values of …

Feasibility Study Of An Integrated Safety Seat For Infants And Children Under The Age Of Two Traveling In Commercial Aircraft, Muneer A. Bakhsh

Master's Theses - Daytona Beach

The purpose of this study was to investigate the feasibility of integrated safety seat for children and infants onboard commercial aircraft. The researcher collected and analyzed data on the subject of safety seats for children and infants onboard commercial aircraft. The 115 participants for this study were randomly selected from the population of parents boarding commercial aircraft with infants and/or children. The research method used was descriptive and also compared the integrated safety seats for infants and children in automobiles to commercial aircraft. The survey examined whether or not parents were interested and willing to pay for an integrated safety …

The Impact Of The Simulated Digital Data Radio Communication Induced Interference On Voice Radio Communication, Daniela T. Kratchounova

Master's Theses - Daytona Beach

The transition of air/ground communications, from its present analog structure to a new digital communications architecture, will span a 10-year time frame. Testing to date indicates that the potential for interference from the digital system to the analog system would be critical, especially for General Aviation (GA) aircraft. This type of interference can be described as short, random bursts of noise capable of completely obliterating parts of the voice communication. The subsequent degrading effects on voice radio communications could jeopardize flight safety. The masking of parts of important information would result in distracted attention, debilitated cognitive performance, high level of …

General Aviation Aircraft: A Comparative Analysis Of Analog Instrument Display And Conceptual Primary Flight Display, Ungul Laptaned

Master's Theses - Daytona Beach

The primary purpose of this study was to evaluate the effects that analog instrument display versus primary flight display (PFD) had on pilot performance. Pilot performance was evaluated by: (a) time, and (b) number of errors. There were twenty subjects with a minimum of a private pilot license selected from the Aeronautical Science department at Embry-Riddle Aeronautical University. Three flight conditions (spoiler problem, engine problem, and flap failure) acting as a control group was given to the flight students while flying a traffic pattern. A Silicon Graphics® flight simulation software program and a video camera were used as the data …

An Intermittent-Combustion General Aviation Aircraft Engine Exhaust Noise Prediction Algorithm, Hiroko Tada

Master's Theses - Daytona Beach

From an environmental point of view, the reduction of aircraft noise has become an important factor recently. There are two factors that make airplane noise: propeller noise and engine noise. This report puts emphasis on only the engine noise in order to begin understanding what airplane engine exhaust noise is. At first, the engine exhaust noise is comprehended using the Dobrzynski's engine noise theory. Next, a discussion about an Embry-Riddle Aeronautical University (ERAU) engine system, engine exhaust system configurations, and microphone setting standards that show the ERAU engine system exhaust noise data. Finally, an Intermittent-Combustion (IC) General Aviation (GA) aircraft …

A Thin-Film Micromanufactured Oxygen Microelectrode, James Clay Mcguyer Jr.

Doctoral Dissertations

The methods for production of recessed oxygen microelectrodes developed by Whalen, et al. (1967) and improved upon by Linsenmeier, et al. (1987) are dated production methods by the standards of sensor production of the current time. The production process for this type of polarographic oxygen sensing electrode has remained unchanged for over 10 years, and is a time consuming, extremely low-yield process. The goal of this project has been to use the techniques of micromanufacturing available at the Institute for Micromanufacturing at Louisiana Tech University to construct a recessed oxygen microelectrode with a batch process that has higher yield than …

The Microchannel Flow Of A Micropolar Fluid, Guohua Liu

Doctoral Dissertations

Micro-channel flows have been computed to investigate the influence of Navier-Stokes formulation for the slip-flow boundary condition, and a micro-polar fluid model, respectively.

The results of the slip boundary condition show that the current methodology is valid for slip-flow regime (i.e., for values of Knudsen number less than approximately 0.1). Drag reduction phenomena apparent in some micro-channels can be explained by slip-flow theory. These results are in agreement with some computations and experiments.

An ad hoc micro-polar fluid model is developed to investigate the influence of micro effects, such as micro-gyration, in micro-scale flows. The foundation of the ad hoc …

Cost-Benefit Analysis Of Leasing Versus Buying Air Force General Purpose Vehicles In The Continental United States, Robert J. Neal Jr.

Theses and Dissertations

Given the increasingly aging vehicle fleet and declining vehicle budget, this research performed a cost-benefit analysis of leasing versus buying various Air Force general purpose vehicles for the entire continental United States (CONUS). In contrast to previous analyses, which have examined the leasing versus buying issue on a base-by-base basis, this analysis studies the issue from an Air Force-wide perspective using a cost-buying model. Costs and benefits are calculated for three purchasing options (Air Force ownership, GSA leasing, and commercial leasing) to determine and recommend the best alternative for the Air Force. Finally, a sensitivity analysis is to test the …

The Challenge Of Maintaining Or Replacing An Aging Airlift Fleet: A Cost/Capability Analysis For The Brazilian Air Force Mobility System, Julio C. Messias

Theses and Dissertations

Despite the high Operational and Support costs incurred, the Brazilian Air Force's (BAF) declining budget has led to the establishment of conservative policies that favor short run solutions for a critical BAF airlift problem of operating an aging fleet. As a result of this policy, service life extensions of older airlift aircraft are the preferred solution. Using an equal airlift capacity approach to examine the Brazilian Air Force mobility system, this research performs a cost comparison analysis between two aircraft currently in operation at Brazilian's airlift command: C-130 Hercules and C-95 Bandeirante. To accomplish the cost analysis, this research develops …

An Ex Post Facto Analysis Of E-3 Maintenance Indicators In The 552d Air Control Wing Since Reorganization Under An Aircraft Generation Squadron Concept, Larry J. Stetz

Theses and Dissertations

Organizational restructuring sometimes occurs in the aircraft maintenance field, yet seldom are in-depth analyses performed after the fact to see if productivity improved. In December 1995, the 552D Air Control Wing restructured its flight line maintenance into an aircraft generation squadron concept. This study looked at before and after maintenance indicators to see if productivity improved. Maintenance data was collected from December 1993 to December 1997. Nineteen maintenance indicators were identified, and the key indicators were analyzed using means comparison and regression analysis to determine if efficiency and effectiveness had increased. The variables Mission Capable rate and Man-hours per Flying …

Space-Available Transportation: An Analysis Of The Cost Of Providing 'Free' Travel, Frank J. Long

Theses and Dissertations

The purpose of this study is to estimate the costs borne by the government for providing space-available travel to eligible uniformed services personnel and their dependents. As the primary provider of the space-available privilege, it is important that the Air Force have an estimate of the burden that the administration of that privilege places on the budget. In January 1993, the Air Force discontinued its 15-year-old practice of charging a fee for space-available travel aboard AMC-owned or controlled aircraft. The fee had been set at $10 in 1978 and was collected to recover a portion of the costs associated with …

Operational Risk Management And Military Aviation Safety, Park D. Ashley

Theses and Dissertations

The Air Force Class A aviation mishap rate has hovered around 1.5 mishaps per 100,000 flight hours since 1985. Recent attention on Air Force accidents has caused the leadership to seek to reduce its mishap rate. The Army's Class A aviation mishap rate declined after it implemented risk management (RM) principles in 1987. This reduction caught the attention of Air Force leadership who have since stated that the application of operational risk management (ORM) is how the Air Force will reduce, even eliminate, mishaps. With current budget constraints, ORM is considered to be the most cost-effective way the Air Force …

An Exploratory Analysis Of The Responsiveness Capability Of The Air Expeditionary Wing (Aew) Concept, Robert L. Charlesworth

Theses and Dissertations

Seven AEF deployments have been accomplished in the Southwest Asia area of responsibility; none have met the Air Force's stringent 72 hour criterion. This exploratory study quantifies the responsiveness capability of the AEW concept. Based on a Monte Carlo simulation methodology this study concludes that the on call AEW at Mountain Home AFB does not have the capability to meet the 72 hour criterion. Additionally, this study examined the effect of three departures from the baseline model on responsiveness capability. These departures included: increasing airlift throughput capacity, incorporating limited airlift failure, and employing an air refueling scenario. The simulation models …

Reparable Inventory Reduction: Impacts On Air Force Fighter Aicraft Mission Capability, Gregory E. Hutson

Theses and Dissertations

During the 1990's the Air Force experienced severe declines in serviceable inventory levels and a rise in their TNMCS rates. Air Force predictions of TNMCS hours during this time period did not account for the upward trend in TNMCS rates. The Air Force uses a regression equation, consisting of possessed hours, flying hours, and sorties, to predict TNMCS hours. This research, through simple linear regression, found a significant relationship between serviceable inventory levels and TNMCS rates for 8 of the 10 aircraft studied. Using this relationship, serviceable inventory levels were then added to the Air Force equations and new multiple …

The Privatization Of The Aerospace Guidance And Metrology Center At Newark Air Force Base, Richard H. Fillman Jr.

Theses and Dissertations

The Aerospace Guidance and Metrology Center (AGMC) at Newark AFB was privatized in place as a result of the 1993 BRAC process. This was a first of a kind for the DoD repair depot system. The justification was too much excess depot capacity and by closing Newark the Air Force would rid itself of this excess capacity and obtain savings by privatizing the repair workload. This thesis concentrates on whether excess capacity at AGMC was as large as it was identified and if cost saving had materialized at the depot since the privatization. To determine how well the depot repairs …

Professional Contracting Certification: An Examination And Model Development, Robert D. Lorton, Daniel I. Dunn

Theses and Dissertations

This study compared the elements of existing contracting certification programs to an ideal contracting certification model developed by experts. The expert panel responded to an open-ended electronic interview to convey their ideas regarding the individual elements for the model. Input received from the initial interviews was used to develop a survey for the panel members. The surveys were completed and results were recorded and conveyed back to the panel members. This process was repeated until a majority was reached on each individual element of the model, resulting in the ideal certification model. The final model contained elements of both the …

The Effect Of Action Workouts On Aircraft Mission Capability Measurements, Michael P. Allison

Theses and Dissertations

Previous studies concerning quality improvement and the Action Workout Process attempted to define and describe the difficult concept of quality. A logical next step is to study to what extent implementation of a quality improvement program, such as ACC's Action Workout Process, positively or negatively affects performance factors within an Air Force organization. This study focused on exploring the fundamental question of whether there was, as a result of the Action Workout, a noticeable, statistically verifiable, positive or negative change in the mission capability of aircraft assigned to the units carrying out this quality improvement initiative. Research questions were developed …

Comparison Of The Effects Of Eight-Hour And Twelve-Hour Shifts On Air Force Aircraft Maintenance Production Levels, David P. Collette

Theses and Dissertations

his is a follow-on study that examined the effects of converting a large aircraft maintenance squadron from 8-hour shifts to 12-hour shifts. The squadron studied converted its 24-hour maintenance work force from three 8-hour work shifts to two 12-hour work shifts. Data was collected from four different time periods. Three time periods were used for a primary analysis and all four time periods were used for trend analysis. To determine if the 12-hour work shift was effective, workforce productivity was measured during the different work shift periods. Results showed an increase in two productivity measurements, no-change in two productivity measurements, …