Engineering Commons^™

Spin Polarized Transport In Nanoscale Devices, Sandipan Pramanik

Theses and Dissertations

The ultimate goal in the rapidly burgeoning field of spintronics is to realize semiconductor-based devices that utilize the spin degree of freedom of a single charge carrier (electron or hole) or an ensemble of such carriers to achieve novel and/or enhanced device functionalities such as spin based light emitting devices, spin transistors and femto-Tesla magnetic field sensors. These devices share a common feature: they all rely on controlled transport of spins in semiconductors. A prototypical spintronic device has a transistor-like configuration in which a semiconducting channel is sandwiched between two contacts (source and drain) with a gate electrode sitting on …

Design And Validation Of A Full Contact Gait Simulator For The Cadaveric Lower Extremity, Joseph Michael Iaquinto

Theses and Dissertations

The projects goal was to create a device to simulate full contact gait in the cadaveric lower extremity. The Contact Gait Simulation System loads specific muscles to recreate anatomical dorsi and plantar flexion of the ankle under axial loading. A system of pneumatic load generation was connected a LabVIEW virtual instrument (VI), which controlled the application of these loads. The loads were roughly based off literature cited EMG data, and further modified from feedback. In addition to controlling the load system, the VI also coordinates external sensor timing. Along with this simulator, software was developed specifically for analyzing pressure data …

Detection, Identification And Classification Of Suck, Swallow And Breathing Activity In Premature Infants During Bottle-Feeding, Fedra Adnani

Theses and Dissertations

Prematurity, especially if extreme, is one of the leading causes of problems and/or death after delivery. Among all the problems encountered by premature infants, feeding difficulties are very common. Many premature infants are fed intravenously at first, and they progress to milk feedings provided by a tube passed into the stomach. At around 34 weeks of gestation, premature infants should be able to breastfeed or take a bottle. At the same time such premature infants are usually faced with difficulty making the transition from tube-feeding to full oral feeding. In this study three physiological measurements of premature infants including sucking, …

Experimental Study Of The Entrainment Of Nanoparticles From Surfaces, Srirupa Ganguly

Theses and Dissertations

The adhesion and resuspension of nanoparticles is important in applications ranging from semiconductor manufacturing to pollution management. The objective of this work is to understand the effect of particle size on re-entrainment of nanometer scale particles. One of the major contributions is to reduce the randomness introduced in past measurements on resuspension by controlling humidity, temperature, material and the distribution of shape and particle sizes. In the process of studying particle size, the effect of surface roughness was also found. Measurements of the detachment fraction of carbon particles as a function of flow rate show three distinct regimes that we …

Optical Characterization Of Electrochemically Self-Assembled Compound Semiconductor Nanowires, Sivakumar Ramanathan

Theses and Dissertations

Semiconductor nanowires have attracted considerable attention as possible source for lasers and optical storage media. We report the fabrication and optical characterization of ZnO and CdS nanowires. The former are produced by electrochemical deposition of Zn inside nanoporous alumina films containing regimented arrays of 10nm, 25nm and 50 nm diameter pores, followed by room temperature chemical oxidization. Fluorescence spectroscopy shows different characteristics associated with different sample diameter. The 50 nm ZnO nanowires show an exciton recombination peak and an additional peak related to the deep trap levels. 25 nm ZnO nanowires show a only the exciton recombination peak, which is …

Computational Modeling To Predict Mechanical Function Of Joints: Validations And Applications Of Lower Leg Simulations, Peter C. Liacouras

Theses and Dissertations

Computational models of musculoskeletal joints and limbs can provide useful information about joint mechanics. Validated models can be used as a predictive device for understanding joint function and serve as a clinical tool for predicting the outcome of surgical procedures. A new computational modeling approach was developed for simulating joint kinematics that are dictated by bone/joint anatomy, ligamentous constraints, and applied loading.Three-dimensional computational models of the lower leg were created. Model development involved generating three-dimensional surfaces from CT images, followed by importing these surfaces into SolidWorks and COSMOSMotion. ThroughSolidWorks and COSMOSMotion, each bone surface was created into a solid object …

Design And Development Of Oligonucleotide Microarrays And Their Application In Diagnostic And Prognostic Estimation Of Human Gliomas, G. Scott Taylor

Theses and Dissertations

DNA microarrays represent an ultra-high throughput gene expression assay employed to study the transcriptomic profiles of biological tissues. These devices are increasingly being used to study many aspects of gene regulation, and there is growing interest in the biotechnology and pharmaceutical industries for developing such devices in efforts toward rational product/drug design. The DNA microarray also provides a unique and objective means for diagnosis and prognosis of human diseases based on patterns of gene expression. This is especially important in cancer research and the thrust toward personalized medicine. This dissertation details the design and development of oligonucleotide microarrays and the …

A Wireless Surface Electromyography (Wsemg) System, Aleeta E. Bell

Theses and Dissertations

Surface Electromyography (SEMG) systems are utilized throughout the medical industry to study abnormal electrical activity of the human muscle. Historically, SEMG systems employ surface (skin) mounted sensors that transmit electrical muscle data to a computer base via an umbilical cord. A typical SEMG analysis may exercise multiple sensors, each representing a unique data channel, positioned about the patient's body. Data transmission cables are linked between the surface mounted sensor nodes and a backpack worn by the patient. As the number of sensors increases, the patient's freedom of mobility decreases due to the lengthy data cables linked between the surface sensors …

The Implementation Of Nanoimprint Lithography For The Fabrication Of Patterned Magnetic Media, Daniel David Marks

Theses and Dissertations

Advances in technology are having profound effects throughout society. This is no truer than in the way information is being stored. The primary form of information storage for at least the past millennium has been paper. Today, an ever increasing amount of information is being stored electronically. An increased demand for high-performance, low-cost information storage has been a major catalyst in increasing the popularity of hard drives. In 2002, two exabytes of original information was stored on hard drives. This is ten times the amount of all printed material in the world if it were converted to electronic files. To …

An Algebraic Reconstruction Technique (Art) For The Synthesis Of Three-Dimensional Models Of Particle Aggregates From Projective Representations, Daniel Jonathan Randall-Barrot

Theses and Dissertations

There exists considerable evidence that the shear behavior and flow behavior of granular materials is significantly dependent on particle morphology. However, quantification of this dependence is a challenging task owing to a dearth of quantitative models for describing particle shape and the difficulty of modeling angular particle assemblies. The situation becomes more complex when discrete element analyses of realistic 3-D particle shapes are required. The thesis attempts to address this problem by adapting the algebraic reconstruction technique (ART) to synthesize composite 3-D granular particles from statistically obtained 3-D shape descriptors of the particles in an aggregate mixture. This thesis extends …

Predicted Redidual Strength Of Damaged Isotrussâ® Structures, Travis S. Carroll

Theses and Dissertations

This thesis utilized a linear analytical approach to explore the damage tolerance or residual strength as a function of increasing damage in traditional single and hybrid-grid IsoTruss® structures. Residual strength was studied for structures subjected to axial compression, torsion and flexural bending, independently. Carbon/epoxy material properties were applied in all load cases, and fiberglass/epoxy material properties were also applied in the flexural bending case. Prior to imposing damage conditions, the IsoTruss® structures were parametrically optimized to achieve the highest strength-to-weight ratios. Typical compression strut, driveshaft, and utility pole specifications governed the design strength dimensions and boundary conditions. Damage growth was …

Dynamic Aeroelastic Analysis Of Wing/Store Configurations, Gregory H. Parker

Theses and Dissertations

Limit-cycle oscillation, or LCO, is an aeroelastic phenomenon characterized by limited amplitude, self-sustaining oscillations produced by fluid-structure interactions. In order to study this phenomenon, code was developed to interface a modal structural model with a commercial computational fluid dynamics program. LCO was simulated for a rectangular wing, referred to as the Goland⁺ wing. It was determined that the aerodynamic nonlinearity responsible for LCO in the Goland+ wing was the combination of strong trailing-edge and lambda shocks which periodically appear and disappear. This mechanism limited the flow of energy into the structure which quenched the growth of the flutter, resulting …

Multiple Channel Laser Beam Combination And Phasing Using Stimulated Brillouin Scattering In Optical Fibers, Brent W. Grime

Theses and Dissertations

Brightness scaling lasers using stimulated Brillouin scattering (SBS) in optical fibers is explored. A multiple-channel amplifier approach is used to increase the total power of a laser system while avoiding a significant burden on a single channel. The work explores two approaches utilizing both SBS beam cleanup and SBS piston error conjugation. A unique beam combiner that takes advantage of the SBS beam cleanup properties of a long, gradient-index multimode fiber was designed and tested. The beam combiner was developed to combine multiple-channel laser beams simultaneously with high input and output coupling efficiency. The design for the SBS beam combiner …

A Detailed Approach For Concept Generation And Evaluation In A Technology Push Product Development Environment, Andrew Nelson

Theses and Dissertations

Many companies rely on successful product development as a means to increase their revenues and expand their operations. Market pull, the most common form of product development, begins with a specific customer, and focuses on how to satisfy that customer's needs. Technology push is a product development process where a technology is first discovered, then embodied in products that may be marketed to specific customers. Technology push presents several obstacles not encountered in market pull processes, such as a lack of a defined market, lack of established processes and difficulty in execution. These complications keep technology push from being more …

Statnamic Lateral Load Testing And Analysis Of A Drilled Shaft In Liquefied Sand, Seth I. Bowles

Theses and Dissertations

Three progressively larger statnamic lateral load tests were performed on a 2.59 m diameter drilled shaft foundation after the surrounding soil was liquefied using down-hole explosive charges. An attempt to develop p-y curves from strain data along the pile was made. Due to low quality and lack of strain data, p-y curves along the test shaft could not be reliably determined. Therefore, the statnamic load tests were analyzed using a ten degree-of-freedom model of the pile-soil system to determine the equivalent static load-deflection curve for each test. The equivalent static load-deflection curves had shapes very similar to that obtained from …

Leveraging Itil To Govern Aoc Information Technology, Robert V. Weaver Iii

Theses and Dissertations

The Air Operations Center (AOC) is a complex system of systems that is resistant to traditional engineering controls and management strategies. The US Air Force (USAF) seeks to transform its antiquated AOC Information Technology (IT) management function into an agile enterprise capable of leveraging cutting-edge technology by aligning the AOC's infrastructure with its organizational strategies and vision. The USAF calls this effort a transformation. Private industry calls it IT Governance. To achieve AOC IT Governance, the USAF must stop managing infrastructure components and start managing IT services. IT Service Management abstracts business processes from the technology supporting them by creating …

Characterization Of Binary Offset Carrier (Boc) Systems Coexisting With Other Wideband Signals, John M. Hedenberg

Theses and Dissertations

Results for modeling, simulation, and analysis of interference effects that modern interfering signals have on the system performance of the Binary Offset Carrier (BOC) signals, such as the Global Positioning System (GPS) Military System (M-Code signal) are addressed in this work. Three signals are addressed as potential interferers. These include the current GPS clear/acquisition code (C/A-Code) signal, the current GPS precision code (P-Code) signal, and an Orthogonal Frequency Division Multiplexed (OFDM) signal. All of these potential interferers are modeled as coexisting within the same bandwidth as the M-Code signal. Interference effects are characterized by comparing the bit error performance of …

Modeling, Stability, And Control Of A Rotatable Tail On A Micro Air Vehicle, Travis J. Higgs

Theses and Dissertations

This research uses existing experimental wind tunnel data to develop a non-linear model that is used to characterize the stability of a flexible wing Micro Air Vehicle (MAV) with a rotatable tail. The experimental data are curve fit based on either angle of attack or angle of sideslip, and the coupled effect of tail rotation and tail deflection on the force and moment coefficients. Static optimization trims the input and state variables for Steady Level Unaccelerated Flight (SLUF). The resulting initial conditions are fed to an open loop non-linear Simulink/Matlab simulation. The study found that the bare MAV design is …

Green Engineering And Gate-To Gate Life Cycle Assessments For Pharmaceutical Products, Daniel Fichana

Theses and Dissertations

The research of this thesis focused on the environmental and processing metrics during the development of two different drugs. Previous research in life cycle assessments and green engineering have focused on other products and processes, but only a limited amount of studies have been conducted for pharmaceutical applications. This analysis concerned a gate-to-gate analysis of two distinct pharmaceutical products along with the development of a solvent selection table. The goal of this research was to determine how various processing and environmental metrics were affected by process improvements.

The first drug was the pravastatin, which was made via a fermentation route. …

Performance Measurements Of Direct Air Injection In A Cavity-Based Flameholder For A Supersonic Combustor, Scott G. Edens

Theses and Dissertations

For several years the Air Force Research Lab Propulsion Directorate has been studying the difficulties in fueling supersonic combustion ramjet engines with hydrocarbon based fuels. Recent investigations have focused on the use of direct air injection into a directly-fueled cavity-based flameholder. Direct air injection has been shown qualitatively to be a valuable tool for improving cavity combustion. Little quantitative data is available that characterizes the performance of cavity-based flameholders. The objective of this research was to quantitatively determine the specific advantages and disadvantages of the direct air injection scheme. This was accomplished via intrusive probing into a supersonic free stream …

Wind Tunnel Study Of Interference Effects Relating To Aft Supersonic Ejection Of A Store, Timothy P. Jung

Theses and Dissertations

An investigation into the issues surrounding the release of a store into a supersonic wake was conducted. A 10-degree half-angle cone was used to model the carrier vehicle as well as the store. The store was 42% than the vehicle. The experiments were conducted at a freestream Mach number of 2.93 and at zero degrees angle of attack. This study analyzed the effects of a support or strut mounted under the wind tunnel model. Research was conducted on the effects of a store at various positions in the wake, as well as the effects of a rear cavity in the …

Gaussian Mixture Reduction For Bayesian Target Tracking In Clutter, David J. Petrucci

Theses and Dissertations

The Bayesian solution for tracking a target in clutter results naturally in a target state Gaussian mixture probability density function (pdf) which is a sum of weighted Gaussian pdf's, or mixture components. As new tracking measurements are received, the number of mixture components increases without bound, and eventually a reduced-component approximation of the original Gaussian mixture pdf is necessary to evaluate the target state pdf efficiently while maintaining good tracking performance. Many approximation methods exist, but these methods are either ad hoc or use rather crude approximation techniques. Recent studies have shown that a measure-function-based mixture reduction algorithm (MRA) may …

Preliminary Design Approach For Prosthetic Ankle Joints Using Compliant Mechanisms, Jason Matthew Wiersdorf

Theses and Dissertations

The objective of this thesis is to develop design approaches and models for prosthetic ankle joints using kinematic models of the human ankle and compliant mechanisms technology. Compliant mechanisms offer several potential design advantages over traditional rigid-body designs including high reliability and low cost. These design advantages are ideal for use in prosthetics. Some prosthetic ankle/foot systems currently on the market have multiple degrees of freedom yet are expensive. Additionally, even though these systems have multiple degrees of freedom, none of them are designed after the actual movements of the biological ankle. In this thesis a two, single degree-of-freedom hinge …

Simulation For Evaluating The Usability Of Integrated Flight Decks, Troy Ricardo Weeks

Theses and Dissertations

There is a modern revolution of pilot interface designs as technological advancements force industrial progress in general aviation (GA). Recent accident statistics and safety reports indicate that computerized flight decks in Technically Advanced Aircraft (TAA) present novel safety hazards. Little empirical data have been used to measure the usability of integrated flight decks due to the complexity and time-consuming nature of flight data assessment. The objectives of this thesis are (1) to describe the human factors issues that are induced by the design of the integrated flight deck, (2) to demonstrate the evaluative capabilities of a TAA flight simulator, and …

An Investigation Of Employee Satisfaction And Employee Empowerment Specific To On-Site Supervisors In The Residential Construction Industry, David Lars Halvorsen

Theses and Dissertations

Employee satisfaction and empowerment are vital elements to businesses in most industries. The construction industry has various types of employees, ranging from managers and executives to on-site supervisors and laborers. This study was conducted to obtain a greater understanding about the elements and levels of satisfaction and empowerment of on-site supervisors in the residential construction industry. An on-site supervisor in the residential construction industry is responsible for coordinating and managing employees, materials, equipment, budgets, schedules, contracts, and the safety of employees and the general public. They are also the employees most frequently perceived as accountable for the success or failure …

A New Method For The Rapid Calculation Of Finely-Gridded Reservoir Simulation Pressures, Benjamin Arik Hardy

Theses and Dissertations

A new method for the determination of finely-gridded reservoir simulation pressures has been developed. It is estimated to be as much as hundreds to thousands of times faster than other methods for very large reservoir simulation grids. The method extends the work of Weber et al. Weber demonstrated accuracies for the pressure solution normally requiring millions of cells using traditional finite-difference equations with only hundreds of cells. This was accomplished through the use of finite-difference equations that incorporate the physics of the flow. Although these coarse-grid solutions achieve accuracies normally requiring orders of magnitude more resolution, their coarse resolution does …

Interior Node Projection Techniques In Sweeping Algorithms, Michael Andrew Scott

Theses and Dissertations

The enhancement of node projection techniques in sweeping is the subject of this thesis. Sweeping is a method used to produce all-hexahedral finite element meshes on certain classes of geometry. The placement of nodes in the interior of the geometry during the sweeping process remains a difficult problem. This thesis presents advancements in this area which improve the speed of the algorithm and the resulting element quality. A comparison of existing projection methods was performed. The existing Faceted projection sweeping method was extended to be applicable to more general classes of sweepable geometry. This comparison and extension of node projection …

A Gasless Method Of Spraying Thermoplastic Resin, Dan T. Rogers

Theses and Dissertations

This spraying method for thermoplastic resins is a new manufacturing process for applying thermoplastics to a mold or surface in an efficient way that has the potential of reducing cycle time. Spraying thermoplastic resins is similar to spraying other polymers, such as paint, with the differences being higher pressure and temperature. This method uses an injection molding machine with a modified nozzle to spray the plastic material. In this study, temperature, pressure, and nozzle size were factors that influenced the success of this spraying method. The method of spraying in this study proved spraying without a gas is possible, a …

Object Oriented Cae Software For The Exploration And Design Of Microstructures, Stephen D. Sintay

Theses and Dissertations

Through the use of generalized spherical harmonic basis functions a spectral representation is used to model the microstructure of cubic materials. This model is then used to predict the macroscopic elastic and plastic properties of materials with cubic crystal symmetry and various sample symmetry including triclinic and axial—symmetric. Building on the work of citeN{Barnett-FractureMechanics} the influence that anisotropy has on the fatigue response of the material is also modeled. This is accomplished through using the effective elastic stiffness tensor in the computation of crack extension force G. The resulting material model and macroscopic property calculations are the foundation for …

Mpsa Effects On Copper Electrodeposition: Understanding Molecular Behavior At The Electrochemical Interface, Clint Gordon Guymon

Theses and Dissertations

In this work the structure of the electrochemical metal-liquid interface is determined through use of quantum mechanics, molecular simulation, and experiment. Herein are profiled the molecular dynamics details and results of solid-liquid interfaces at flat non-specific solid surfaces and copper metal electrodes. Ab initio quantum-mechanical calculations are reported and define the interatomic potentials in the simulations. Some of the quantum-mechanical calculations involve small copper clusters interacting with 3-mercaptopropanesulfonic acid (MPSA), sodium, chloride, bisulfate and cuprous ions. In connection with these I develop the electrode charge dynamics (ECD) routine to treat the charge mobility in a metal. ECD bridges the gap …