Engineering Commons^™

Making The Business Case For Sustainable Design In The Department Of Defense, David M. Warnke

Theses and Dissertations

Buildings are one of the largest consumers of natural resources, a major source of ecological pollution, and occasionally toxic to human health. Sustainable design is the common term associated with buildings which, during their construction, use, and eventual disposal, seek to minimize their negative impact on the environment and human health. The U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) rating system helps to assess a building's sustainability level. In the Federal Government's push to set the example for the rest of the nation, nearly every Federal Agency has chosen to adopt the LEED assessment tool. Each …

Stepped Waveguide Electromagnetic Material Characterization Technique, Sean P. Dorey

Theses and Dissertations

Electromagnetic material characterization is the process of determining the complex permittivity and permeability of a material. A new waveguide material measurement technique is developed to reduce test sample size requirements for low-frequency applications. Specifically, a waveguide sample holder having a reduced aperture is utilized to decrease the time and cost spent producing large precision test samples. This type of sample holder causes a disruption in the waveguide-wall surface currents that results in the excitation of higher-order modes. This thesis will demonstrate how these higher-order modes can be accommodated using a modal-analysis technique, thus resulting in the ability to measure smaller …

An Analysis Of Coast Guard Hh-65 Engine Reliability: A Comparison Of Malfunctions To Component Removals, Donna L. Cottrell

Theses and Dissertations

The Coast Guard HH-65 helicopter experienced 31 in-flight loss of power incidents during FY 2003 and 21 during the first two months of FY 2003. Concurrent with this apparent decrease in reliability, the Coast Guard seeks ways to expand the HH- 65’s Airborne Use of Force capabilities as a result of the September 11th, 2001 terrorists’ attacks. This study is an exploratory, empirical analysis of engine and airframe component replacements as related to engine mishaps and reliability in the HH-65. We use contingency table analysis, ordinary least squares regression, and logistic regression to examine the mishap history and component replacement …

Optimal Constellation Design For Orbital Munitions Delivery System, Jason Anderson

Theses and Dissertations

Rather than delivering conventional munitions through the airspace of uncooperative nations, a constellation of space-stored weapons could potentially target any point on the Earth and arrive within the time it takes to de-orbit and re-enter through the atmosphere. The research involves applying the dynamics of atmospheric re-entry to a Common Aero Vehicle (CAV) and defining a footprint of attainable touchdown points. The footprint is moved forward to create a swath representing all the possible touchdown points in a 90 minute window. A nominal constellation of CAVs is established using a streets of coverage technique, and both analytic studies and numeric …

Effects Of Friction Stir Welding On Polymer Microstructure, Seth R. Strand

Theses and Dissertations

This work establishes the relationships between several key Friction Stir Welding process parameters and the resulting microstructural and flexural properties of the welded joint. A series of four single parameter experiments were run. The parameters investigated were pin diameter, feedrate, shoe temperature, and pressure time. Butt welds were made in 6 mm thick stress-relieved extruded polypropylene sheet. Three-point bend tests were used to determine the ultimate flexural strength and coincident strain. The maximum bend angle before failure was used to label the welds as "good or bad." An optical microscope capable of cross polarization was used to examine and photograph …

Integrated Microbattery Charger For Autonomous Systems, Brian W. Lefevre

Theses and Dissertations

This thesis presents a microbattery recharging circuit suitable for autonomous microsystems. The battery charger chosen for this design is a constant current battery charger. Two methods of regulating the constant-current are discussed. A published shunt regulator design is analyzed and is presented with enhancements to the design. A series regulator that controls the current to the battery with a switch is designed and fabricated in a 1.5µm CMOS process. The fabricated prototype occupies less than 2.20x2.20mm and is expected to dissipate less than 25µW of power. A discrete model of the integrated circuit is constructed and tested to demonstrate that …

Evaluation Of Interlayer Bonding In Hot Mix Asphalt Pavements, Stephen M. Gomba

Theses and Dissertations

This study investigates the potential of falling weight deflectometer (FWD) data for use in quantifying the level of interlayer bonding achieved in pavements. Data was obtained and used from the Federal Aviation Administration's (FAA) National Airport Pavement Test Facility located in Atlantic City, New Jersey. In this test facility, a section of the pavement had encountered a loss of bond between lifts of the surface hot mix asphalt (HMA) layer. FWD tests had been performed at locations throughout the pavement, on a monthly basis for the duration of the loading period. The FWD data, along with detailed material property data, …

Outside Loop Control In Asymmetrical Trimmed Flight Conditions, Gary D. Miller

Theses and Dissertations

Traditionally flight control systems have used linearized equations of motion solved around a single trim point. This thesis proposes a nested-loop controller directly solved from the equations of motion. The control equations were developed as a solution to asymmetrically trimmed flight conditions. A two-loop design was proposed for the controller. The outer loop modeled the aircraft as a point mass and all forces were balanced to find the aircraft states. The equations input the control variables and output the aircraft states. The inner-loop utilizes the six-degree of freedom model of the aircraft to solve the moment equations. With the input …

Studies In Multiple-Antenna Wireless Communications, Christian Bruce Peel

Theses and Dissertations

Wireless communications systems are used today in a variety of milieux, with a recurring theme: users and applications regularly require higher throughput. Multiple antennas enable higher throughput and/or more robust performance than single-antenna communications, with no increase in power or frequency bandwidth. Systems are required which achieve the full potential of this "space-time" communication channel under the significant challenges of time-varying fading, multiple users, and the choice of appropriate coding schemes. This dissertation is focused on solutions to these problems. For the single-user case, there are many well-known coding techniques available; in the first part of this dissertation, the performance …

Rocket Plume Particulate Characterization By Multiple Wavelength Opacity And Mie Scattering, Andrew P. Chouinard

Theses and Dissertations

In the presented work, experiments were conducted to assess the utility of plume opacity monitoring for hybrid rocket diagnostics. The first phase of the work involved measuring plume opacity at a single wavelength and then at two wavelengths simultaneously. Results showed excellent correlation between plume opacity and rocket motor firing cycle and correlation between plume opacity and oxidizer flow rate, thereby validating the utility of the technique. Additionally, a spectral dependence of plume opacity was demonstrated that indicated the possible presence of transparent particulates in the plume. Further phase 1 experiments investigated the performance requirements of a laser-based instrument to …

Electrospinning As A Processing Method For Electroactive Polymers And Composites, Kristin Joy Pawlowski

Theses and Dissertations

Electrospinning was examined for its potential to create functional materials. Three distinct electroactive materials were electrospun into fibers and fiber mats and then characterized with the intent of determining their utility in aerospace and biomedical applications such as micro-air vehicles and the cardiovascular system. Electrospun Graft Elastomers demonstrated potential as actuators, as electromechanical strain testing showed comparable response to the film form of this material. Further improvement of electroactive response was realized with high dielectric inclusions and fiber orientation. Electrospin processing imparted piezoelectric properties to the fibers of poly(vinylidene fluoride). Differential scanning calorimetry and infrared spectroscopy indicated a degree of …

Characterization Of Aligned Carbon Nanotube/Polymer Composites, Sumanth Banda

Theses and Dissertations

The main objective of this thesis is to efficiently disperse and align SWNTs in two different polymer matrices to obtain an orthotropic composite whose strength, stiffness and electrical properties depend on the orientation of the SWNTs. The SWNTs are successfully dispersed and aligned in a polyimide matrix and a polymer blend of UDMA/HDDMA. In-situ polymerization under sonication is used to disperse the SWNTs in polyimide matrix and sonication is used to disperse SWNTs in the UDMA/HDDMA matrix. In both cases, an electric field is used to align the SWNTs in the polymer matrices. In the polyimide, the SWNTs are aligned …

Luminescence In Zno, Jin Xu

Theses and Dissertations

As a wide band semiconductor with a large binding energy (about 60meV), ZnO is a promising candidate semiconductor material for the next generation of optoelectronic , light emission or high power and high frequency devices. In order to make electrical device from ZnO, it is necessary to investigate optical properties of ZnO.In this thesis, PL setup and the properties of ZnO are introduced briefly and the optical properties of ZnO are investigated in detail. Temperature dependence of PL spectra of ZnO are measured and analyzed. Sharp emission line of PL spectra of rare earth (RE) doped ZnO are also investigated.

High Quality Zno Epitaxial Grown By Plasma Assisted Molecular Beam Epitaxy, Yun Zhang

Theses and Dissertations

Described in this thesis are the growth and characterization of high quality ZnO epitaxy layers.Zinc oxide (ZnO) epitaxy layers were grown on sapphire and epi-GaN substrates respectively, using plasma assisted molecular beam epitaxy (MBE) . Various growth conditions, such as growth temperature, II/VI ratio, and buffer layers, were employed to optimize the quality of the ZnO film. The subsequent characterization of the films was carried out to evaluate the surface, optical and crystalline properties of the film, using AFM, SEM, PL and XRD techniques. It was found out that the high quality of the ZnO film was grown on epi-GaN …

Incorporation Of Tetracycline Hydrochloride Into Electrospun Fibrinogen: A Study Of Mechanical Properties And Time Release, Charles Dudley Anderson Jr.

Theses and Dissertations

Electrospinning has the capacity to create fibers of natural or synthetic polymers with dimensions that are similar to analogous fibers in native tissue. Mats consisting of fibers of these sub-micron dimensions have shown promise in provoking little immune response and in offering a habitable environment for cell proliferation. Fibrinogen is a natural protein capable of being electrospun and offers the benefit of existing as part of the natural coagulation cascade. Mats of fibrinogen could be utilized as possible hemostatic dressings or as an early scaffold for cell migration for either wound repair or tissue engineering. The addition of antibiotic into …

Gan Epitaxy On Melt Grown Thermally Prepared Bulk Zno Substrates, Xing Gu

Theses and Dissertations

Different methods were developed for the preparation of bulk ZnO substrates. Remarkable improvement on the surface, optical and crystalline quality of the bulk ZnO substrate was achieved. ZnO substrates with an atomically flat surface exhibiting terrace-like features were used as a substrate for GaN grown by MBE. High-resolution x-ray diffraction and low temperature PL results show that similar high quality GaN layers can be achieved on both annealed O-face and Zn-face ZnO substrates. The prospect of the device applications of GaN epitaxy on ZnO, including AlGaN/GaN MODFET structure on ZnO and GAN/ZnO based p-n junction were discussed.

Iii-Nitride Semiconductors Grown By Plasma Assisted Molecular Beam Epitaxy, Lei He

Theses and Dissertations

III-nitride semiconductors are of great interest owing to their commercial and military applications due to their optoelectronic and mechanical properties. They have been synthesized successfully by many growth methods. Among them, molecular beam epitaxy (MBE) is a promising epitaxial growth method owing to precise control of growth parameters, which significantly affect the film properties, composition, and thickness. However, the understanding of growth mechanism of III-nitride materials grown in this growth regime is far from being complete.In this dissertation, GaN and AIGaN growth mechanism under metal-rich conditions were investigated. The Ga surface desorption behavior during the growth was investigated systematically using …

Novel Apparatus To Control Electrospinning Fiber Orientation For The Production Of Tissue Engineering Scaffolds, Eugene David Boland

Theses and Dissertations

The conception of electrospinning can trace its roots back more than 400 years, when it was observed that rubbed amber can deform a droplet of water on a smooth surface, and is based upon simple concepts of charge separation and surface tension. Since that time, considerable effort has been directed at both the cause and utility of this phenomenon. The specific aim of this dissertation project was to develop an automated electrostatic processing apparatus that was capable of controlling the three-dimensional architecture of an electrospun scaffold to further improve its utility in tissue engineering. The efficacy of using this technique …

Spatially Varying Threshold Models For The Automated Segmentation Of Radiodense Tissue In Digitized Mammograms, Richard Edson Eckert Iii

Theses and Dissertations

The percentage of radiodense (bright) tissue in a mammogram has been correlated to an increased risk of breast cancer. This thesis presents an automated method to quantify the amount of radiodense tissue found in a digitized mammogram. The algorithm employs a radial basis function neural network in order to segment the breast tissue region from the remainder of the X-ray. A spatially varying Neyman-Pearson threshold is used to calculate the percentage of radiodense tissue and compensate for the effects of tissue compression that occurs during a mammography procedure. Results demonstrating the efficacy of the technique are demonstrated by exercising the …

Multi-Sensor Data Fusion Using Geometric Transformations For The Nondestructive Evaluation Of Gas Transmission Pipelines, Philip James Kulick

Theses and Dissertations

Nondestructive evaluation (NDE) plays a vital component in the operation and maintenance of large infrastructure such as gas transmission pipelines, nuclear power plants, aircraft, bridges and highways, etc. As this infrastructure continues to age it is essential that the inspection techniques reliably and accurately predict the integrity of these systems. No single NDE method is capable of inspecting all types of anomalies and extracting all required information – a combination of methods must be used and the resulting data fused. Moreover, newer systems that are developed are often made of composite materials that include metals and dielectrics. One interrogation modality …

Hdl Implementation Of A Controller Area Network Node, Anthony Richard Marino

Theses and Dissertations

With increasing technology inside automobiles, especially law enforcement vehicles, there is a growing need for centralized wiring and device interconnection methods. Each new technology, such as GPS navigation units and in-vehicle video systems, includes a corresponding wiring harness that needs installation. The summation of all these hardwired technologies leads to large volumes of wire that negatively affect safety, power demands, and future design opportunities. A new trend among automotive manufacturers is to design and implement innovative networks that allow for shared communications between technologies.

This thesis presents the design, development, and implementation of an in-vehicle network that will centralize connections …

Evaluation Of The Flail Space Model Utilizing Event Data Recorder Technology, Douglas John Gabauer

Theses and Dissertations

Developed in the early 1980's, the flail space model has become the standard method for estimating occupant risk in full-scale crash tests involving roadside safety features. The widespread availability of airbags and increased seat belt usage rates in today's vehicle fleet, however, raise serious questions regarding the validity of the model. Recent implementation of Event Data Recorder (EDR) technology in a number of late model vehicles presents a different perspective on the assessment of the validity of occupant risk based on the flail space model. EDRs are capable of electronically recording data such as vehicle speed, brake status and throttle …

Development Of An Augmented Haptic Control For In-Vehicle Law Enforcement Applications, Edward R. Guest Iii

Theses and Dissertations

Typical police vehicles are filled with as much technology as the department can afford. Everything from the newest digital camera system to a simple entertainment radio is within the reach of an officer. Currently, most of these systems are installed without any consideration toward the other systems or the interaction required between the driver and the car. The lack of a systems approach in the installation has spawned a project to look at the safety and overall system installation in the New Jersey State Police vehicles.

The research presented in this thesis suggests consolidation of the various controls into one …

Wind Scatterometry With Improved Ambiguity Selection And Rain Modeling, David W. Draper

Theses and Dissertations

Although generally accurate, the quality of SeaWinds on QuikSCAT scatterometer ocean vector winds is compromised by certain natural phenomena and retrieval algorithm limitations. This dissertation addresses three main contributers to scatterometer estimate error: poor ambiguity selection, estimate uncertainty at low wind speeds, and rain corruption. A quality assurance (QA) analysis performed on SeaWinds data suggests that about 5% of SeaWinds data contain ambiguity selection errors and that scatterometer estimation error is correlated with low wind speeds and rain events.

Ambiguity selection errors are partly due to the "nudging" step (initialization from outside data). A sophisticated new non-nudging ambiguity selection approach …

Establishing A Quantitative Foundation For Exactly Constrained Design, Alisha M. Hammond

Theses and Dissertations

Exactly constrained (EC) design is a robust design method which can be used for mechanical assemblies. It entails using the minimum number of constraints to eliminate all desired motion.

While found by some engineers in industry to have many benefits (including robust assembly, no binding or play, ease of assembly, and the ability to tolerate the wear of parts), EC designs remain somewhat unrecognized by academia. One reason for this minimal exposure may be the lack of a quantitative foundation for such designs. This thesis describes the history and current background for EC designs, and it also begins to develop …

Selecting Appropriate Product Concepts For Manufacture In Developing Countries, Danielle Johnson

Theses and Dissertations

There is a noticeable lack of production of indigenously engineered and manufactured products in Less Developed Countries (LDC's). Few products developed in these LDC's could be viable in competitive markets or even sold as components and supplies to other manufacturers of competitive goods. Assumintg that these less developed countries do not innovate and manufacture because they cannot, the next logical question to ask is why can they not?

This thesis looks at the problems of manufacture and design in LDC's from the standpoint of Product Development. It begins by looking at development theories, namely top down and bottom up and …

Rotational Molding Of Acrylonitrile-Butadiene-Styrene Polymers And Blends, Mark Grant Spencer

Theses and Dissertations

The development of acrylonitrile-butadiene-styrene (ABS) resins for use in rotational molding would provide a medium performance material, thus opening doors to new markets for the rotational molding industry. Unfortunately, ABS resins have shown serious problems during the rotational molding process, namely discoloration, bridging, and poor impact strength. It is believed that these effects are due to degradation of the carbon-carbon double bond in the butadiene, through attack by either oxygen or heat. Previous efforts have shown some success in addressing these issues. However, additional improvements are necessary to make ABS resins commercially viable to rotational molders. This study, fourth in …

Satellite Scatterometers: Calibration Using A Ground Station And Statistical Measurement Theory, Peter Kenneth Yoho

Theses and Dissertations

Satellite scatterometers have recently gained popularity due to their unique ability to measure global geophysical data on a daily basis. Increased interest in scatterometry mandates improved design and calibration of these instruments. This dissertation presents new techniques for scatterometer calibration and addresses issues related to the design of future instruments and applications. First, the use of a calibration ground station is considered. A new methodology is established for calibration of SeaWinds, NASA's current scatterometer, using a receive-only ground station. Principles of the methodology are implemented, new analysis techniques developed, and important results obtained for instrument timing, frequency, power, position, and …

Evaluation Of Event Data Recorders In Real World Crashes And Full-Scale Crash Tests, Lewis Thomas Clayton Jr.

Theses and Dissertations

With the advent of advanced safety systems in U.S. passenger vehicles, there has been increased interest shown by automakers in recording crash related parameters that ultimately lead to the deployment of these safety systems in what are known as Event Data Recorders (EDRs). Since the only other record of these parameters, specifically crash pulse, comes from staged crash tests in a controlled environment, the advent of the EDR has become increasingly important to crash researchers. The purpose of this study is to quantify the performance of EDRs in full-scale crash tests and real world crashes.

Comparison of EDRs with staged …

Modeling The Transient Response Of A Thermosyphon, James Kirk Storey

Theses and Dissertations

Thermosyphon transient operation was numerically modeled. The numerical model presented in this work overcame the limitations of previous studies by including transient conduction in the vessel wall, shear stress between the rising vapor and the falling film in the thermosyphon, the influence of the mass in the liquid pool in the evaporator, and by using a more refined and accurate numerical grid. Unique to this model was the accounting for temporal changes in the effective length of the vapor space due to the expanding and contracting of non-condensable gases in the vapor space. The model assumed quasi-steady one-dimensional vapor flow, …