Engineering Commons^™

The Current Voltage Characteristics Of Electron Beam Controlled Thin Film Diamond Switches, Christopher Anthony Molina

Electrical & Computer Engineering Theses & Dissertations

The dark current of natural diamond thin films and the induced current due to electron-beam irradiation was measured up to a range of 7000Ncm'. The contact material was aluminum, annealed and unannealed. Switching experiments were performed with electron energies ranging from 70keV to 172keV. The switching results obtained are strongly dependent on the biasing polarity, incident electron energy, and whether the contact is blocking or Ohmic in nature. A simple model which takes traps into consideration allows us to explain the various switching responses. The range of electrons which define, in part, the switch mode was measured for one sample …

An Approach For Representation Of Organizational Mental Models Using System Dynamics, Jörg-Peter Theissen

Engineering Management & Systems Engineering Theses & Dissertations

The concept of mental models has received much attention within recent years, especially within the context of organizational learning. This research is based on and departs from the Organizational Learning Process as developed by Keating, Robinson, and Clemson (1994). That process, which is based on a verbal representation of mental models, does not call forth the kind of change that is desired in Organizational Learning. This research investigates if mental models can be represented in the form of system dynamics models and inquires if this representation is beneficial to the process of Organizational Learning.

The research was designed as a …

Generalized Reverse Theorems For Multipass Applications In Matrix Optics, Lee W. Casperson, Anthony A. Tovar

Electrical and Computer Engineering Faculty Publications and Presentations

The reverse theorem that governs backward propagation through optical systems represented by transfer matrices is examined for various matrix theories. We extend several reverse theorems to allow for optical systems represented by matrices that may or may not be unimodular and that may be 2 × 2 or take on an augmented 3 × 3 form. As an example, we use the 3 × 3 form of the reverse theorem to study a laser with intracavity misaligned optics. It is shown that, by tilting one of the laser's mirrors, we can align the laser output arbitrarily, and the mirror tilt …

Biofeedback Gait Training Auditory Vs. Visual Techniques, Timothy D. Hiemenz

Electrical & Computer Engineering Theses & Dissertations

Training lower extremity amputees to walk normally is quite a difficult task. Amputees must wear a prosthesis so they can walk at all. This allows them some mobility, but their walking pattern may be unnatural. If their gait is temporally asymmetric, they need to exert more energy to move about. This research was initiated to help lower extremity amputees to walk more efficiently using biofeedback gait training. Two types of feedback were developed and tested to determine which method gave the most understandable feedback, validating its use in a clinical setting.

A normal gait cycle uses the lower limbs to …

Defining Locally Shared Memory Constructs For Special Purpose Parallel Architectures, David J. Nielsen

Electrical & Computer Engineering Theses & Dissertations

Locally shared memory systems offer significant advantages over other parallel processing systems for specific classes of problems. Locally shared memory systems tend to be easier to program because explicit passing of messages is not necessary. The goal in defining a locally shared memory system is to allow only a small number of processors access to any single memory. If this goal is met, locally shared memory systems provide an architecture which is relatively simple to implement.

To make shared memory architectures attractive to designers of special purpose parallel architectures, the architectures must be scalable. To be scalable, the number of …

A Novel Microwave Method For Detection Of Long Surface Cracks In Metals, Chin-Yung Yeh, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

A novel microwave technique for detecting long surface cracks in metals is described. This technique utilizes an open-ended waveguide to probe the surface of a metal. In the absence of a crack the metal surface is seen as a relatively good short-circuit load. However, in the presence of a crack higher order modes are generated which in turn change the reflection properties at the waveguide aperture. This change brings about a perturbation in the standing wave characteristics which is then probed by a diode detector. The experimental and theoretical foundations of this technique are given, along with several examples. It …

Analysis Of Motor Vehicle-Deer Accidents In Kentucky, Kenneth R. Agent

Kentucky Transportation Center Research Report

An analysis of motor vehicle-deer (deer) accidents for the five-year period of 1989 through 1993 was conducted. There was an average of about 2,800 deer accidents per year. This type of accident was generally not severe with almost 96 percent property-damage-only accidents. Trends were noted in time and date of the accidents. The highest percentage of deer accidents occurred between 6 and 10 pm and in November and December. The percentage of this type of accident was highest in western and northern Kentucky and lowest in southeastern and central Kentucky. The accident rate for this type of accident was highest …

A Study Of The Thermodynamic And Heat Transfer Characteristics Of Two-Phase Two-Component Flow With Application To A Solar-Assisted Heat Pump, Walid A. Aziz

Mechanical & Aerospace Engineering Theses & Dissertations

Two-phase flow of single component refrigerants has been studied, theoretically and experimentally, for many CFCs, in many industrial applications, including the solar-assisted heat pump system. This study extends the thermodynamic and heat transfer analysis in the phase transition boiling region, to newly proposed refrigerant mixtures, which are candidates for replacing the classical CFCs for future HVAC applications. The goal of this study is to develop a methodology, to design the collector/evaporator tubes of a solar-assisted heat pump, using a binary refrigerant mixture as the working fluid. The method is implemented numerically as a computer algorithm. In order to do that, …

Bs News

Building Services Engineering

No abstract provided.

Complex Index-Of-Refraction Measurements For Rp-1 Liquid Rocket Fuel, Dennis R. Alexander, Ramu Kaiwala, Robert D. Kubik, Scott A. Schaub

Department of Electrical and Computer Engineering: Faculty Publications

Complex index-of-refraction values of RP-1 liquid rocket fuel are reported at laser wavelengths of 0.193 m (ArF excimer), 0.4765 m (argon ion), 0.488 im (argon ion), 0.5145 ji.m (argon ion), 0.532 m (Nd-YAG, frequency doubled), 0.6328 pm (He-Ne), 1 .064 im (Nd-YAG), and 10.5915 im (C02). The imaginary part of the index of refraction (k) is determined by traditional transmission methods. The real part (flr) at the specific laser lines is determined using reflectance measurements, critical-angle measurements, Mueller matrix elements, and Michelson interferometric measurements. Reflectance measurements are used to obtam n at a wavelength of 0.193 m. The critical-angle method …

Resonant Tunneling Through Quantum Dot Arrays, Guanlong Chen, Gerhard Klimeck, Supriyo Datta, Guanhua Chen, William A. Goddard Iii

Birck and NCN Publications

We apply the Hubbard Hamiltonian to describe quantum-dot arrays weakly coupled to two contacts. Exact diagonalization is used to calculate the eigenstates of the arrays containing up to six dots and the linear-response conductance is then calculated as a function of the Fermi energy. In the atomic limit the conductance peaks form two distinct groups separated by the intradot Coulomb repulsion, while in the band limit the peaks occur in pairs. The crossover is studied. A finite interdot repulsion is found to cause interesting rearrangements in the conductance spectrum.

Circuit Modeling Of Switched Linear Networks, Fardin Ansari

Dissertations and Theses

The use of switched linear networks is prevalent in power processing systems such as dc-to-dc power converters. These converters provide regulated dc output power and are widely used in the power supplies for computers and peripherals. As with most systems where high performance is a criterion, the power converter is usually enclosed in a feedback loop. Feedback design usually entails the use of small signal (linear) models with linear feedback design techniques. There exists a large number of small signal models, but most of them are ad hoc. A describing function approach has previously been presented which determines the exact …

Using Polyster Waste With Cotton Waste On Open - End Spinning Machine, Rizk El-Bealy, Ismail Mousa Rakha, F. Fahim

Mansoura Engineering Journal

The present work intended to study the spinning performance of mixed "cotton/polyester" waste fibers from existing mills on open-end spinning machine, cotton waste fibers "comber nolls, card strips and penu mafil" were extracted from cotton fiber Giza 75 and polyester card strips were used. The blends and preliminary processing equipment are selected correctly and rotor machine is set correctly. The mixed waste fibers are spun mainly into yarn ranging from 98 tex to 22.7 tex at maximum properties. The results fédiéete that the blend of polyester waste fibres with cotton waste composition resulted in increasing the effective fibre length of …

Acuta Enews September 1994, Vol. 23, No. 9

ACUTA Newsletters

In This Issue

Board report

President's message

Just Say Yes

Developing Excellence

Conference photos

The Confident Decision Maker

Positive about Change

Information Highway

An Econometric Analysis Of The Canada - Florida Air Passenger Market, Craig W. Poteet

Master's Theses - Daytona Beach

This thesis evaluates the Canada - Florida commercial air passenger market and explains fluctuations in the demand for air passenger service based on an econometric modeling process. Canada - Florida commercial air passenger traffic is segmented into those passengers flying on scheduled air services and those travelling on chartered air services. Two separate multiple regression equations are constructed to address the two segments of the Canada - Florida market. Both equations are formulated utilizing the same three independent variables. It was expected that the three chosen independent variables, Canadian GDP, a ratio of chartered air fare levels by scheduled air …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 7, September 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

An eight page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Analysis Of Efficiency Measures For Block Diagonal Machine-Component Charts, Hamid Seifoddini, Manocher Djassemi

Industrial Technology and Packaging

Group efficiency measures have been developed to evaluate machine-component charts for the formation of cellular manufacturing systems. In this paper the existing grouping efficiency measures will be evaluated by determining the relationship between the values of a grouping efficiency measure and the performance of the corresponding cellular manufacturing system.

Decision Support Model To Compare Hazardous Waste Site Remediation Process Alternatives, Christopher E. Findall

Theses and Dissertations

This research focuses on the development of a decision support model to identify the preferred methods of site characterization and treatment technology identification using the principles of decision analysis theory. The model provides an effective decision making tool to evaluate and compare the feasibility of using alternative methods of completing the RIFS process. Given a specific site remediation project, the users of this model can enter site- specific cost, duration and likelihood values to determine the expected value for various alternative processes. This thesis postulates that the alternative having the highest expected value is considered the preferred alternative. In calculating …

An Analysis Of Alternative Methods Of Measuring Hazardous Waste Reduction Progress At The Air Force Materiel Command's Air Logistic Centers, Edward C. Finke

Theses and Dissertations

his study investigated the relationship between aircraft related maintenance activity and the amount of hazardous waste (HW) disposed of by Air Force Materiel Command's (AFMC) Air Logistic Centers (ALC). These ALCS, along with the Aircraft Guidance and Meteorology Center, generate approximately 76 percent of the HW generated by the Air Force. The activity indexing and least squares curve fitting methods were used to predict the amount of HW that would have been disposed of based on the relative level of aircraft related maintenance activity had no pollution prevention efforts been implemented. These predictions were then compared to what historically occurred …

Application Of A Risk Model To Quantify Relative Risk Of Remedial Actions, Timothy L. Fuller

Theses and Dissertations

To properly manage the Installation Restoration Program (IRP) in the future, Air Force remedial project managers (RPMs) need a metric to assist in the selection of remedial alternatives for the safe and effective clean up of waste contamination sites. If the baseline site risk assessment indicates that it is necessary to remediate a waste contamination site, it is important to the RPM that the selection process for remediation alternatives considers the potential human health and ecological risks associated with the proposed remediation process. In some instances, the risks may be significant when compared to the baseline conditions. The Air Force …

Modeling Trihalomethane Formation Potential From Wastewater Chlorination, Carol A. Mccormick

Theses and Dissertations

The deletion of federally mandated fecal coliform limits has led many states to review and modify their wastewater disinfection requirements. One issue in analyzing wastewater disinfection is the discharge of potentially carcinogenic halogenated organics formed during the chlorination process. This research investigates the formation of one class of the halogenated organics, the trihalomethanes. The applicability of using drinking water trihalomethane formation models for use with wastewater effluent is examined. Three models are compared for predictive capability by using measured trihalomethane values from previous research data. The results show that a previously developed model is applicable for use based on assumptions …

Optimal Utilization Of Field Generated Analytical Data For Site Characterization And Remedial Decision Making, Ronald J. Lester

Theses and Dissertations

This study developed data quality standards for assessing environmental analytical data quality and its use in remedial decision making, specifically in risk assessment calculations. The primary purpose was to increase the use of field generated data in environmental site investigations versus the continued reliance on costly and time consuming EPA Contract Lab Program data. Increased reliance on field lab data could significantly reduce remedial investigation costs. The standards developed are based on regulatory criteria for data useability, achievable quality in a CLP lab setting, and basic statistical methods. The standards were applied to sets of Volatile Organic Compound data in …

Volatile Organic Compound Emissions From Usaf Wastewater Treatment Plants In Ozone Nonattainment Areas, Brian A. Ouellette

Theses and Dissertations

In accordance with the 1990 Clean Air Act Amendments CAAA, this research conducts an evaluation of the potential emission of volatile organic compounds VOCs from selected Air Force wastewater treatment plants. Using a conservative mass balance analysis and process specific simulation models, volatile organic emission estimates are calculated for four individual facilities--Edwards AFB, Luke AFB, McGuire AFB, and McClellan AFB--which represent a cross section of the current inventory of USAF wastewater plants in ozone nonattainment areas. From these calculations, maximum facility emissions are determined which represent the upper limit for the potential VOC emissions from these wastewater plants. Based on …

Evaluation Of Alternative Methods For Wastewater Disinfection, David C. Piech

Theses and Dissertations

This study investigated the alternative methods of wastewater disinfection. Areas of interest included methods of operation, ease of maintenance, and effectiveness for various types of wastewater. A literature search revealed three major disinfection options, which include chlorination dechlorination, ultraviolet light, and ozone. A questionnaire was sent to the active duty Air Force installations that operate wastewater treatment plants, requesting permit limitations and monthly averages for a variety of wastewater parameters. The majority of Air Force wastewater treatment plants use chlorine for disinfection. Using the data obtained from the questionnaire responses and established wastewater parameters from other research, the basic design …

Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio

Theses and Dissertations

This research focuses on the development of a simulation model to determine the effects of hydrological influences on a wetland ecosystem. The model allows perturbations to the inputs of various wetland data which in turn, influences the successional development of the ecosystem. This research consisted of converting a grassland ecosystem model to one which simulates wetland conditions. The critical factor in determining the success of wetland creation is the hydrology of the system. There are four of the areas of the original model which are affected by the hydrology. The model measures the health or success of the ecosystem through …

Standardization Of Protocol For The Sampling, Testing And Abatement Of Asbestos Containing Joint Compound, Gary J. Schneider

Theses and Dissertations

This study investigated the differing regulatory guidelines from the Occupational Safety and Health Administration and the Environmental Protection Agency concerning the abatement of Asbestos Containing Joint Compound (ACJC). The specific interest was whether or not adequate protection was being afforded demolition workers when exposed to working with ACJC materials that contain less than 1.0 percent asbestos. A spreadsheet was written to estimate the exposure scenario which might be experienced within a given room size on a demolition or renovation jobsite. Spreadsheets were calculated for ACJC with an asbestos content of 0.1 to 0.9 percent in 0.1 increments for rooms ranging …

A Preliminary System Dynamics Model Of A Constructed Wetland For The Mitigation Of Metals In Usaf Storm Water, Mark P. Smekrud

Theses and Dissertations

This thesis determines the potential removal and corresponding accumulation of trace metals from Air Force storm water in a constructed wetland through the use of a System Dynamics model. The goal is to determine whether constructed wetlands used as storm water best management practices provide efficient metal removal while creating only benign accumulations of such pollutants. Its purpose is to allow Base Civil Engineers and Environmental Managers a better tool to assess the long-term effects of a constructed wetland used as a storm water mitigation technique. The research is limited to the assessment of typical metal concentrations found in Air …

Solvent Substitution Methodology Using Multiattribute Utility Theory And The Analytical Hierarchical Process, Jaimie S. Tiley

Theses and Dissertations

This study developed a multicriteria decision making methodology for the ranking of solvent cleaning process alternatives. This includes development of univariate value functions and criteria and the incorporation or required alternative attributes. It also compares the Analytical Hierarchical Process and Multiattribute Utility Theory in reference to a cleaning substitution process. An actual Air Force cleaning process evaluation problem is considered to verify the research. The test problem ranks several cleaning alternatives for the replacement of a hazardous solvent used in the general cleaning of aircraft engine components.

Status Of Storm Water Pollution In The United States, Lynne A. Urquhart

Theses and Dissertations

The purpose of this study was to determine the status of storm water pollution in the United States Air Force. This is important since most AF bases are now required to have applied for a NPDES storm water permit. The objectives of the study were to: evaluate the sampling rates used at AF bases; determine the pollutants tested for by the AF bases; compare the pollutant concentrations of the AF bases to an EPA water quality standard; and determine if there were any trends in sampling or pollutant concentrations due to seasonal changes or across AF Commands or EPA Regions. …

Developing An Emission Factor For Hazardous Air Pollutants For An F-16 Using Jp-8 Fuel, Donald J. Van Schaack

Theses and Dissertations

The 1990 Clean Air Act amendments drastically changed the legislation of hazardous air pollutants HAPs or air toxics. Title 3 of the act which specifically addresses HAPs now lists 189 substances which may require regulation as air toxics. Consequently, the reporting of HAP emissions from all Air Force operations will be required in the future. However, the Department of Defense DoD does not have methods available to report this information. This thesis develops emission factors for selected HAPs from an F-16 CD aircraft F110 engine operating on JP-8 fuel. The methodology included determining which HAPs should be selected, using past …