Engineering Commons^™

Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli

Theses and Dissertations

Micro-Raman (µ-Raman) spectroscopy is used to measure residual stress in two silicon carbide (SiC) poly-types: single-crystal, hexagonally symmetric 6H-SiC, and polycrystalline, cubic 3C-SiC thin films deposited on Si substrates. Both are used in micro-electrical-mechanical systems (MEMS) devices. By employing an incorporated piezoelectric stage with submicron positioning capabilities along with the Raman spectral acquisition, spatial scans are performed to reveal areas in the 6H-SiC MEMS structures that contain residual stress. Shifts in the transverse optical (TO) Stokes peaks of up to 2 cm^-1 are correlated to the material strain induced by the MEMS fabrication process through the development of phonon …

Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz

Theses and Dissertations

There are a number of analytical and semi-empirical models that describe the behavior of particulate matter in the atmosphere. Many of these require modification for all types of weather, dry versus wet deposition, and overall effects can be quite non-linear. Rainfall (rate, drop size, etc.), snowfall (rate, flake size, etc.), humidity, pressure, temperature, and combination of these greatly affect particle settling and washout rates. To that end, a method for tracking released constituents using the Regional Atmospheric Modeling System (RAMS) microphysics package is developed by modifying one of the hydrometeor categories (hail) in the microphysics package. The RAMS microphysics package …

A Comparison Of The Heft Subsurface And Delfic Particle Size Distributions And Effects In Hpac, Eric T. Skaar

Theses and Dissertations

The Heft subsurface three component lognormal fallout particle size distribution is compared and contrasted with the single lognormal fallout particle size distribution used by the Defense Land Fallout Interpretive Code (DELFIC). Comparison of the two distributions is accomplished with results from the AFIT smear code and the Hazard Prediction and Assessment Capability (HPAC). The effect of the distributions is explored in HPAC for varying yield weapons, varying surfaces, precipitation conditions, varying wind effects and varying dose rate times. The results from the two distributions are quantitatively compared using the concepts of grounded source normalization constant and the rate at which …

Temperature Dependent Current-Voltage Measurements Of Neutron Irradiated Al0.27Ga0.73N/Gan Modulation Doped Field Effect Transistors, Troy A. Uhlman

Theses and Dissertations

In this research, the first ever neutron irradiation study of AlGaN/GaN MODFETs was conducted. Devices irradiated to a total 1 MeV Eq (Si) neutron fluence of 1.2x10¹⁶ n/sq cm demonstrated the temperature dependence of irradiation and annealing. Devices irradiated at 80 K exhibited significant persistent electrical degradation at only 5.4 rad (Si), whereas those irradiated at elevated temperatures exhibit transient increases in gate and drain current up to 400 krad (Si). I-V measurements indicate substantial radiation-induced increased gate and drain currents occur only at low-temperature irradiations. The introduction of a high-density of donor defects is hypothesized as the primary …

Modeling Groundwater Flow And Contaminant Transporting Fractured Aquifers, Jason M. Bordas

Theses and Dissertations

The hybrid discrete fracture network/equivalent porous medium (DFN/EPM) model was selected for analysis and application to simulate a contaminated site in this study. The DFN/EPM was selected because it appeared to have the potential to aid decision making by remedial project managers at contaminated DoD fractured aquifer sites. This model can use data that are typically available at a site while incorporating the important processes relevant to describing contaminant transport in a fractured medium. The model was applied to simulate the operation of a pump-and-treat remedial action at a trichloroethene-contaminated fractured aquifer at Pease AFB. The model was able to …

Using Value-Focused Thinking To Evaluate The Practicality Of Ground-Source Heat Pumps At Military Installations, Jimmy J. Jeoun

Theses and Dissertations

Because of potential cost and energy savings, military decision-makers may want to consider the use of energy-efficient heating, ventilating, and air-conditioning (HVAC) systems at their installations. Ground source heat pumps (GSHPs), in particular, show great promise because of their low energy requirements and low life-cycle costs. However, there currently exists no design guidance or established criteria for HVAC selection. Consequently, military decision-makers have no basis for comparing conventional HVAC systems and GSHPs. The Value-Focused Thinking (VFT) methodology was used to create a multi-objective decision analysis model that measures the value of different HVAC systems. Consisting of five bottom-tier values and …

Comparing Management Approaches For Automatic Test Systems: A Strategic Missile Case Study, William C. Ford

Theses and Dissertations

From 1980 to 1992, the DoD spent over $50 billion acquiring Automatic Test Systems (ATS) used to test weapon systems. At that time, procuring unique ATS to support single weapon systems was the norm. In 1994, the DoD made a dramatic change to their ATS acquisition policy; common ATS that supported multiple weapon systems was preferred over ATS tailored to support a single weapon system. Expected benefits of this new policy included: more reliable equipment, increased supportability, decreased cost, smaller logistics footprint, and decreased manning. To date, the common ATS initiative has garnered little support AF-wide due to lack of …

Output Analysis And Comparison Of Deployment Models With Varying Fidelity, Matthew M. Gill

Theses and Dissertations

This thesis explores the changes in insights that result from using different types of models to assess the capability of deploying the Stryker Brigade within specific timeline goals. The thesis uses as its primary base a study conducted in 2002 by USTRANSCOM to evaluate the ability of Stryker to meet stated deployment timeline goals. Specifically, the author compares the outputs from four different models as they change over three different deployment scenarios and 10 different routes. The study investigates the relationships among the outputs of spreadsheet models, spreadsheet models with elements of variability added, and low- and high-level discrete-event simulations. …

Evaluating Management Strategies For Automated Test Systems/Equipment (Ats/E): An F-15 Case Study, Jeremy A. Howe

Theses and Dissertations

The management of United States Air Force ATS/E presents a variety of issues that affect the long-term capability and mission readiness of weapon systems. Traditional procurement processes suggest that individual aircraft platform System Program Offices (SPOs) developed, improved and replaced ATE on an "as-required" basis. Increased obsolescence, however, and a concern for maintaining longer-term viability provided the necessary inertia for a movement towards the procurement and development of consolidated, common test equipment that would support multiple weapon systems. In 1998, the Air Force Chief of Staff directed HQ AFMC to establish a Common Support Equipment office to facilitate the combination …

Estimating Resource Requirements To Support Multi-Echelon F-15e Deployments, David R. Maxwell

Theses and Dissertations

Since the end of the Cold War, the United States has become focused on developing the capability to rapidly respond to emerging crises. Strategic and operation planning play key roles in order to effectively implement this concept. During the planning process, separate courses of action (COAs) are developed. These COAs are evaluated based upon their operational effect, resource availability, nuclear and transportation feasibility. Currently, transportation feasibility assessments are based on the resources contained within a full Unit Type Code (UTC). Some COAs are eliminated based on these factors. However, most deployments occur at reduced levels. Situational factors, such as the …

Determining Pacaf Transportation Alternatives To The General Purpose Vehicle, Andrew H. Pate

Theses and Dissertations

Vehicle fleets under gird the mission of Air Force bases. Under funding for vehicle replacement requirements raised concerns and has led to purchasing alternative vehicles classified as equipment items to supplement budget shortfalls. In order to effectively use funds and meet mission requirements, Pacific Air Force (PACAF) commanders need an adjustable multifactor decision tool that will allow them to make an informed purchasing decision from among appropriately classified equipment item vehicles. This research will discuss existing regulatory restrictions to alternative transportation purchases, consider available alternative vehicles, and determine the attributes important to vehicle purchases. A review of current Air Force …

Optimization Model For Base-Level Delivery Routes And Crew Scheduling, Young-Ho Cha

Theses and Dissertations

In the U.S. Air Force, a Logistic Readiness Squadron (LRS) provides material management, distribution, and oversight of contingency operations. Dispatchers in the LRS must quickly prepare schedules that meet the needs of their customers while dealing with real-world constraints, such as time windows, delivery priorities, and intermittent recurring missions. Currently, LRS vehicle operation elements are faced with a shortage of manpower and lack an efficient scheduling algorithm and tool. The purpose of this research is to enhance the dispatchers' capability to handle flexible situations and produce "good" schedules within current manpower restrictions. In this research, a new scheduling model and …

Stochastic Capability Models For Degrading Satellite Constellations, Cole W. Gulyas

Theses and Dissertations

This thesis proposes and analyzes a new measure of functional capability for satellite constellations that incorporates the instantaneous availability and mission effectiveness of individual satellites. The capability measure yields a continuous score between zero and one accounting for the degree to which the constellation meets operational requirements. The measure is computed from an average of satellite capabilities, composed of the product of the satellite's instantaneous availability and value score. Instantaneous availability is acquired by modeling the satellite degradation status as either a time-homogenous, continuous-time Markov chain (CTMC) if it possesses functions with exponential lifetime distributions, or as a time-homogenous, semi-Markov …

An Investigation Of The Effects Of Correlation And Autocorrelation In Classifier Fusion With Non-Declarations, Frank M. Mindrup

Theses and Dissertations

Air Force doctrine requires reliable and accurate information when striking targets. Further, this doctrine states that fusion should be utilized whenever possible to ensure the best possible information is conveyed; there is no specific guidance as to how to fuse this information. This thesis extends the research found in Leap, Bauer, and Oxley (2004) to include a non-declared class. The Identification system operating characteristic (ISOC) was adapted to allow for non-declarations both at the individual sensor level as well as the fused output level. A probabilistic neural network (PNN) was also used as a fusion technique. A cost function was …

Selection And Application Of Distorted Risk Measures, Edwin J. Offutt

Theses and Dissertations

This thesis develops and illustrates a methodology for the selection of probability distributions and distortion functions associated with risk scenarios resulting from military capability shortfalls. Distorted (or transformed) risk measures are analyzed and applied to account for loss scenarios that may occur with low frequency but result in catastrophic outcomes. After reviewing the rudimentary concepts of distortion, four well-known continuous distributions, suitable for modeling risk scenarios, are chosen using defined criteria. Based on subject matter expert inputs, a simple method for assigning exactly one of the four distributions to any risk scenario is proposed. Four parametric distortion functions from the …

Optimal Sampling Of A Chemical Hazard Area, Jennifer R. Plourde

Theses and Dissertations

This thesis proposes a methodology for optimally sampling a chemical hazard area subsequent to a chemical weapons attack. The objective is to identify the maximum number of areas that no longer require protective gear for safe operations. We model the area as an undirected graph and employ network analysis techniques to provide a methodological framework for identifying an optimal sampling sequence within a fixed time limit. We propose four models that characterize the secondary vapor concentrations: i) static and deterministic, ii) static and stochastic, iii) dynamic and deterministic, and iv) dynamic and stochastic. Comparisons of the static cases and their …

Strategic Airlift En Route Analysis And Considerations To Support The Global War On Terrorism, Michael C. Sere

Theses and Dissertations

The Global War on Terrorism has mandated the need for additional global en route airfields. En route airfields consist of bases that are strategically located at intermediate locations between the Continental United States and the intended theater of operations. These airfields serve as refueling, crew staging, or maintenance stops for strategic airlift aircraft flying transoceanic routes. The focus of this study is to examine concepts to meet this need and to address important aspects that should be considered in devising new en route strategies. Based on various important factors associated with potential en route airfields, a goal programming methodology was …

An Evaluation Of Wind Turbine Technology At Peterson Afb, Randy C. Combs

Theses and Dissertations

Wind energy technology is a viable source for attaining the emission reduction and renewable energy use goals set forth by the executive office. In accordance with Executive Orders, the Air Force must reduce greenhouse emissions and energy consumption, and expand the use of renewable energy sources within its facilities nation-wide by year 2010. This mandate requires that the Air Force look at alternative electrical production and rely more on such renewable energy resources as wind power. The specific problem addressed by this research is whether on-site wind energy generation can be more economically feasible than the conventional energy consumption at …

A Qualitative Study Of Industry And Air Force Commodity Council Processes, Robert J. Irvine

Theses and Dissertations

The purpose of this research was to compare industry and Air Force commodity council processes. More specifically, this research used a survey to gather strategic sourcing philosophies and procedures (with respect to small business participation in procurement strategies) from successful industry firms. Industry source selection documentation, applicable government contracting guidelines, and a literature review of strategic sourcing materials were also reviewed. The current Air Force commodity council process and associated historical documents were then studied using a business process modeling tool. It was determined that the Air Force process differs from industry in how small business participation is addressed, the …

Vfr Into Imc: Helping Students Avoid Ga's Number One Killer, Dale R. Wilson

All Faculty Scholarship for the College of Education and Professional Studies

No abstract provided.

Swelling Pavement: Ky 499 Estill County, Tony L. Beckham, Tommy C. Hopkins

Kentucky Transportation Center Research Report

A field and laboratory investigation was performed to determine why excessive swelling was occurring on a pavement section of KY Route 499 that was about four years old. Swelling occurred on a section of roadway that had been constructed with a hydrated lime-stabilized subgrade. As shown by laboratory swell tests, swelling of the pavement was due to the absorption of water and expansion of the compacted clay shale subgrade. Results of laboratory swell tests showed that the hydrated lime stabilization of the shale actually reduced swelling. Chemical reactions between calcium, present in the hydrated lime, and sulfates, which were present …

Development Of Multiple Growth Strategies For Use In Developing Traffic Forecasts: A Robustness Approach, Deogratias Eustace, Eugene R. Russell, E. Dean Landman

Civil and Environmental Engineering and Engineering Mechanics Faculty Publications

Decisions that may be based on misleading forecasts may lead to a misallocation of funds and to under-performing projects during construction and operation. Poor projections of demographic and socioeconomic data are usually cited as the major source of poor traffic assignment projections and hence, unfavorably conceived planning and construction of street and highway infrastructure facilities.

This report evaluated the accuracy of long range projections by using a transportation study done the in 1970s, projecting transportation demand 20 years into the future. The projected travel model inputs were compared with what actually happened after the horizon year had been reached and …

Review Of Traffic Provisions Of Krs/Kar And Kentucky Drivers Manual, Kenneth R. Agent, Jerry G. Pigman

Kentucky Transportation Center Research Report

No abstract provided.

Environmental Commitment Follow-Up, Theodore Hopwood Ii, Sudhir Palle

Kentucky Transportation Center Research Report

Three recently completed road construction projects were investigated to determine Kentucky Transportation Cabinet (KYTC) effectiveness in implementing project commitments (including environmental commitments). Documentation was obtained from KYTC districts in which the projects were constructed and KYTC officials involved with the projects from planning through construction were interviewed. The projects were inspected to audit completion of project commitments. Key stakeholders (officials of local governments, resource agencies, MPOs, interest groups, and adjacent landowners) were interviewed about the projects. They were asked to grade KYTC for implementation of project commitments using a standard report card format. The findings for these investigations are presented. …

Analysis And Design Of Switched Capacitor Converters, Jonathan W. Kimball, Philip T. Krein

Electrical and Computer Engineering Faculty Research & Creative Works

Switched capacitor converters have become more common in recent years. Crucial to understanding the maximum power throughput and efficiency is a model of the converter's equivalent resistance. A new form for equivalent resistance is derived and discussed in a design context. Quasi-resonant operation is also explored and compared to non-resonant operation. Several capacitor technologies are evaluated and compared.

Application Of Nonlinear Dynamics Tools For Diagnosis Of Cracked Rotor Vibration Signatures, Jerzy T. Sawicki, Xi Wu, Andrew L. Gyekenyesi, George Y. Baaklini

Mechanical Engineering

The nonlinear model of the cracked Jeffcott rotor is investigated, with the particular focus on study of rotor’s vibrational response using tools of nonlinear dynamics. The considered model accounts for nonlinear behavior of the crack and coupling between lateral and torsional modes of vibrations. Load torque is applied to the rotor which is laterally loadedwith a constant radial force (gravity force) and unbalance excitation. The co-existence of frequencies of lateral modes in the frequency spectra of torsional mode are characteristics of the coupling response of lateral and torsional vibrations. When only the lateral excitations are applied, vibration amplitude bifurcation plot …

Effects Of Central Island Landscape Treatments At Single-Lane Roundabouts, Karen Schurr, Jorge Abos-Sanchez

Nebraska Department of Transportation: Research Reports

No abstract provided.

Multiple-Model Optimization Of Proportional Integral Controllers On Canals, P. J. Van Overloop, J. Schuurmans, R. Brouwer, Charles M. Burt

BioResource and Agricultural Engineering

Canals or open channels that convey water often consist of pools in series separated by control structures. Successful implementation of water-level control with these structures using decentralized proportional integral (PI) controllers depends heavily on the tuning of the control parameters. These parameters are hard to determine due to the interactions between the pools and the varying flow conditions in the canal. This paper presents a procedure for tuning any linear controller (including decentralized PI controllers) that guarantees stability of the controlled canal. It minimizes a cost function that weights the water-level deviations from the target level against control efforts at …

Site Assessments, Martyn Keen

Natural resources published reports

The processes of collecting and recording site data as part of the preliminary tasks leading to a landscape or project design.

This standard applies to landscape and project designs for catchments of any size. Designs include: the installation of conservation earthworks; revegetation; land use planning; or implementation of erosion and sediment control practices. The design may also include any combination of the above

Roaded Catchments, Martyn Keen

Natural resources published reports

A roaded catchment is one of the water harvesting structures known collectively as improved catchments. It has a broad 'V' shaped cross section and a surface cover of clay. It is used to increase run-off yield and divert water to farm dams.