Engineering Commons^™

Superharmonic Resonance Of Second Order For Electrostatically Actuated Mems Cantilevers, Martin Amador Botello

Theses and Dissertations

The nonlinear dynamics of electrostatically actuated micro-electro-mechanical system (MEMS) cantilever resonators are investigated. The applied Alternating Current (AC) voltage is in the realm of superharmonic resonance of the second order (near one-fourth of the natural frequency of the resonator) and hard excitations. Method of Multiple Scales (MMS) and Reduced Order Models (ROMs) are used to solve the dimensionless partial differential equation (PDE) of motion along with boundary and initial conditions. MMS transforms the PDE of motion into zero-order and first-order problems. ROMs uses mode shapes of vibration for undamped cantilever resonator as a basis of functions. ROM is …

Multifunctional Carbon Systems (Interlaminated Carbon Nanofiber Mats/ Carbon Nanotubes Polymer Composites), Homero Gonzalez Guardiola

Theses and Dissertations

Carbon nanomaterials have been an attractive topic within diverse industrial sectors given their outstanding properties for decades. One of the properties that has been calling attention is it’s shielding effectiveness (SE) for electromagnetic interference (EMI), because of the constant race of improving portable electronic and wireless communication devices among other applications. The present study, analyzes the properties of interlaminated Carbon Nanofiber (CNF) mats/Carbon Nanotubes (CNT) polymer composites, emphasizing in its capability to shield EMI. The CNF mats were developed with Polyvinyl alcohol (PVA) as a precursor and by means of the Forcespinning® technology which uses centrifugal force to create fibers …

Lead Doped Carbon Nanofibers In Li-Ion Batteries, Omar Torres

Theses and Dissertations

Lead acid batteries have been a very reliable rechargeable battery since its inception in the mid-1800s. Lithium-Ion batteries have been sought out for their light-weight and capacity of holding large amounts of energy in a small amount of space. Few studies have been conducted in the use of lead in lithium-ion batteries.

In this thesis, lead-doped carbon nanofibers were produced by using the Forcespinning® method and used as an anode on a lithium-ion battery. The morphology, material characterization and thermal properties of the anode material were analyzed using the Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Thermogravimetric Analysis …

Fibers For Skin Regeneration, Astrid Michelle Rodriguez Negron

Theses and Dissertations

This thesis presents the successful development of biocompatible Polyvinyl Butyral (PVB), PVB/Polylysine and PVB/Tannic Acid (TA)/Polylysine fibers from an ethanol solution, Polyhydroxybutyrate (PHB), PHB/Polylysine, PHB/TA/Polylysine fibers from a chloroform solution and Chitosan (CH)/Pullulan (PL)/TA and CH/PL/TA/Polylysine fibers from an aqueous solution. The fibers were mass produced utilizing the Forcespinning® (FS) technology. The morphology of the fibers was characterized using a scanning electron microscope (SEM) and the fibers average diameter was calculated. The thermal properties of the fibers were characterized using a thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC). The antibacterial activity of the fibers was assessed using against …

The Effect Of Heat Generation In The Railroad Bearing Thermoplastic Elastomer Suspension Element On The Thermal Behavior Of Railroad Bearing Assembly, Oscar Osvaldo Rodriguez

Theses and Dissertations

Understanding the internal heat generation of the railroad bearing elastomer suspension element during operation is essential to predict its dynamic response and structural integrity, as well as to predict the thermal behavior of the complete railroad bearing assembly including the bearing adapter. The latter is essential for sensor selection and placement within the adapter (e.g., typical temperature sensors have operating ranges of up to 125°C or 257°F). The internal heat generation is a function of the loss modulus, strain, and frequency. Based on experimental studies, estimations of internally generated heat within the thermoplastic elastomer pad were obtained. The calculations show …

The Use Of Mixed Organic/Ionic Liquid Electrolytes With Forcespun Metal Oxides/Carbon Microfiber Electrodes In Lithium Ion Batteries, Jahaziel Villarreal

Theses and Dissertations

Conventional Lithium-Ion Battery (LIB) electrolytes have serious safety concerns because of highly flammability. In order to mitigate this drawback, alternative electrolytes with low volatility and non-flammable need to be synthesis. Ionic liquids (ILs) and mixed organic ionic liquid electrolytes (MOILEs) are the most suitable replacement for the highly flammable commercial organic electrolytes. In this academic investigation, a new perspective on the electrochemical performance of the ionic liquid EMI-TFSI as an alternate non-flammable electrolyte. In parallel, the use of Forcespun nanofibers as binder-free anodes will be analyzed to further improve overall electrochemical performance.

Assessment Of The Evolving Low-Cost Business Model For The Future Importance Of U.S. Secondary Airports, Nurettin Dinler

Theses and Dissertations

Airline deregulation caused a profound reshape in the aviation industry. The liberalization of the aviation sector resulted in a favorable environment for the emergence of low-cost carriers (LCCs). Following deregulation, airlines saw many attempts at their business strategies to gain more passengers in air transportation market. To capture additional market shares of passenger traffic, the business models of LCCs have evolved to mirror the more common business models employed by the traditional legacy airlines. The purpose of this study was to examine what effect, if any, exists between LCCs’ market share of passenger enplanements at secondary airports and their business …

Positive Experiences As Countermeasures To Stress In Spaceflight: An Investigation Of The Experiences Of Astronauts, Morgan M. Eudy

Theses and Dissertations

Long-duration space mission targets such as asteroids, the Moon and Mars in coming years will increase the need to stress management techniques to support crews on increasingly risky, autonomous missions. New stress management approaches may be found by better understanding the reported positive effects resulting from factors in these environments. This study utilized an exploratory case study approach to leverage quantitative and qualitative data to yield research questions for future correlational analysis. This study found that positive experiences and changes in environmental perspectives occurred from viewing Earth from orbit. Furthermore, this study found that personality factors such as extraversion may …

Modeling And Control Of A 6-Dof Multi-Rotorcraft: Air-Ball, Jerry Ja Wang

Theses and Dissertations

The Air-Ball project seeks to develop an omnidirectional, unmanned aerial vehicle with six degrees of freedom. The Air-Ball vehicle uses six propellers powered by six independent electric motors for propulsion and control. Each motor is attached to a hollow shaft that can rotate ±360° actuated by electric servos. Four of these propulsion shafts are configured in an orientation resembling a quad-copter, where the shafts are 90° apart. The other two propulsion shafts extrude perpendicular from each side of the plane of the quadcopter configuration. Under this unique configuration, Air-Ball is capable of decoupling the motion in the translational and rotational …

Using Dispersive Raman Spectroscopy To Assess Remodeling In Vascular Constructs Used In Tissue Engineering, Andrea S. Theus

Theses and Dissertations

Tissue engineered vascular grafts (TEVGs) are a promising alternative to surgery for the treatment of thrombotic occlusion of small diameter (< 6 mm) arteries. It is important that TEVG composition prevent compliance mismatch. Both initial protein incorporation and cellular remodeling are important for blended TEVG compliance. Understanding the distribution of extracellular matrix (ECM) components is also important and may dictate the remodeling response. Raman spectroscopy has been used to assess components of engineered scaffolds non-destructively. However, Raman has not been applied to semi-quantitatively assess 3D engineered-tissues and cellular remodeling of blended materials with low-scattering natural and high-scattering synthetic components. This is important due to the increased use of synthetic biomaterials for TEVG applications. The overall goal of this study was to develop a technique to assess the cellular and matrix remodeling response. Electrospun meshes were prepared with 100% poly(ε-caprolactone) (PCL), 90% PCL/collagen, and 90% PCL/fibrinogen. XPS and Raman results showed differences of protein distribution when incorporated into a PCL scaffold and differences in the resulting effects with cell culturing and incubation. Raman spectra was acquired for all pure materials individually (e.g. PCL, collagen, and fibrinogen) to determine the unique spectral fingerprint of each material. Protein peaks of interest were identified (e.g. 740 and 1040 cm-¹ ) and were analyzed when protein was incorporated into the electrospun meshes. Raman spectra was acquired for the pure PCL control and blended scaffold conditions. The protein peaks remained relevant for proteins even when incorporated into the high scattering PCL polymer and showed remodeling due to incubation and cell culturing over 21 days. Spectra were also analyzed with multi-factor processing techniques (e.g. MFA) and showed that separation between appropriate sample groups can be achieved even with large amounts of spectral data sets. Biochemical analysis (e.g. Hyp, µ-BCA assay) was done to determine if specific remodeling responses, degradation and/or release occur with incubation and culturing of smooth muscle cells. These results showed a negligible loss of protein within electrospun meshes with incubation and culture. Overall, we have shown that Raman spectroscopy can be used to semi-quantitatively detect the incorporation of low levels of specific proteins (e.g. collagen and fibrinogen) within electrospun meshes as well as changes that occur with mesh remodeling.

Automatic Speech Recognition Adaptation For Various Noise Levels, Azhar Sabah Abdulaziz

Theses and Dissertations

The automatic speech recognition (ASR) is a set of complicated algorithms that convert the intended spoken utterance into a textual form. Acoustic features, which are extracted from the speech signal, are matched against a trained network of linguistic and acoustic models. The ASR performance is degraded significantly when the ambient noise is different than that of the training data. Many approaches have been introduced to address this problem with various degrees of complexity and improvement rates. The general pattern of solving this issue lies in three categories: empowering features, train a general acoustic model and transform models to match noisy …

Speech Emotion Recognition Using Connectionist Models In A Tandem System, Mary Najafi

Theses and Dissertations

This article presents a tandem Speech Emotion Recognition (SER) system by which 8 archetypal emotions can be differentiated based upon two different types of acoustic features as inputs to Artificial Neural Network (ANN) models. The two types of features that are fed into the classifiers reveal the degree of excitement and pleasentness of speech. The author has implied the time-based characteristics of speech in the feature extraction method by monitoring the trend of local features through time. Thus, two global features are proposed that are derived from Teager Energy Operator (TEO)-based (T EOg) and spectral features, Mel-Frequency Cepstral Coeffcients (MF …

Infrared Resonant-Coupled Metamaterial Sensing And Phonon-Polariton-Enhanced Infrared Interconnects, Michael Francis Finch

Theses and Dissertations

Coupled-mode theory has been applied to various fields of endeavor from waveguide splitters/combiners and molecular sensing to light-matter interactions. Metamaterials, engineered periodic or aperiodic structures, are employed to sense molecular vibrational fingerprints in the mid to long infrared wavelengths. A metasurface, a 2D metamaterial, can be designed such that it has a resonance at a molecular vibrational frequency. Mode splitting results from the coupling of two electromagnetic field distributions, or modes, spatially and/or temporally. Metamaterial and molecular resonance coupling is a result of near field interaction. Fano resonances have an asymmetric line-shape that results from the coupling of a continuum …

Effect Of Cavitation Regimes On Stepped Diesel Injectors, David Michael Sykes

Theses and Dissertations

The objective of this work was to determine the effects of different cavitating flow regimes on a stepped orifice geometry relevant to diesel injectors. Conventional diesel orifice geometries consist of a single tapered or straight circular passage. The geometry used in this work had two circular passages in series: a first orifice that was similar to conventional geometries and a second larger orifice immediately downstream that induced cavitation. The large orifice served to stabilize the flow, allowing for different flow regimes to exist at the exit plane of the large orifice (single-phase, intermittent bubbly, bubbly, annular, etc.). A series of …

Cfd Analysis Of Resistance For Stepless And Stepped Planing Hulls, Bhanu Prakash Valtheru

Theses and Dissertations

It is the endeavour of naval architects to design hull forms with the least amount of power consumption. In this respect, Naval Architects have been obsessed with the design of various hull forms optimized for a particular service requiring the lowest amount of fuel consumption keeping in mind effects on the climate change and sustainability. Regardless of the way that a considerable measure of research has been done around this area, there remains a level of uncertainty in the reasonably accurate resistance prediction of stepped hull forms in the early design stage. Model tests and full-scale tests are still the …

An Advanced Context Aware Operator Support System (Caoss) For Chemical Plant Operation, Sujin Babu Alfred Retna Dhason

Theses and Dissertations

Analyzing potential causes for recent industrial accidents and production losses highlights that the majority of these incidents are due to human factor failure: operator error, poor decision-making and violations (Dźwiarek, 2004). In the meantime, the process equipment design, fabrication, metallurgy and control system has improved significantly to combat these unpredictable failures. This research focus on the errors due to human-machine interaction (HMI) in chemical plant. This paper presents an advanced support system for operators in chemical plants, to perform safe and reliable plant operation and maintenance (O&M). In chemical industry, almost every tasks involving human interaction with the machines are …

Helping College Students To Manage Stress: A Human Centered Smartphone Application For Stress Relief, Saad R. Almesalm

Theses and Dissertations

This dissertation represents a Human Centered Design research to evaluate the perception and handling of stress. To successfully evaluate this research, an iOS smartphone application was developed. This research includes five HCD stages: identify needs, research/analysis, design, evaluation and delivery. The importance of this topic was revealed when we realized that stress can affect students internally and externally. We started with understanding the topic and gathering information about stressed students specifically in college. We created an ontology representing the causes of stress based on previous studies. The ontology includes three main factors: Academic, Social, and Personal/Family stress. In addition, the …

Optimization Of Chemical Kinetic Mechanism For Efficient Computation Of Combustion Process In Advanced Internal Combustion Engine Configurations, Muzammil Arshad

Theses and Dissertations

For the development and optimization of future fuels and automotive engines, computer modeling and simulation has proved itself as an inseparable, efficient and cost effective tool to experimental studies. The traditional reliance of computer models on simplified global reaction steps to simulate the combustion and engine performance parameters, such as in-cylinder pressure, heat release rate and pollutant formation could reduce credibility of the predictions as the global reaction steps depend on arbitrary adjustment of model parameters. This study has incorporated detailed chemistry by augmenting the combustion model of a three dimensional unsteady compressible turbulent Navier-Stokes solver with liquid spray injection …

Simulation Based Cost-Benefit Analysis For The Inspection Of Highway Bridges Using Small Unmanned Aerial Systems, Rashmi Kadamkulangara Balagopalan

Theses and Dissertations

Visual inspections remain significantly important in surveying the present decay and deterioration status of bridge inspections. These inspections are critical to conduct patch-up remedies and maintenance assignments to guarantee the continued serviceability of structures. Given the high inventory of bridges nationwide (over of 600,000 bridges), increasing costs of bridge inspections are becoming a concern for departments of transportation (DOTs). The conventional inspection method is costly due to various factors. For example, the current approach often requires specialized equipment (e.g., bucket trucks) to conduct underside bridge inspections that significantly affect safety levels on the field and overall costs, and inspectors need …

Intersection Safety Analysis Methodology For Utah Roadways, Joshua Daniel Gibbons

Theses and Dissertations

Roadway safety continues to be a priority for the Utah Department of Transportation (UDOT) Traffic and Safety Division. UDOT has participated in and managed several research projects in recent years to determine the roadway segments of highest safety concern in the state. This research has provided UDOT with more tools to assist in safety project prioritization. Researchers in Department of Civil and Environmental Engineering at Brigham Young University (BYU) have worked with UDOT and the Statistics Department at BYU to create two network screening statistical tools called the Utah Crash Prediction Model (UCPM) and the Utah Crash Severity Model (UCSM) …

Digital Automatic Speech Recognition Using Kaldi, Sarah Habeeb Alyousefi

Theses and Dissertations

The Automatic speech recognition (ASR) system is one of most important technologies that used for human-machine interaction. The main goal of the ASR system is to recognize different natural languages that are spoken by humans. The difficulties of these recognition systems depend on many factors, such as noises, variability of the speakers, and problems of continuous speech. For that reason, many researchers and foundations have designed different kinds of licensed toolkits and software that are specialized in building speech recognition systems, including , Julius, Sphinx-4, RWTH ASR, and HTK toolkits. In this thesis, Kaldi toolkit, which is one of the …

Pollen Grains Recognition Based On Computer Vision Methods, Amar Idrees Daood

Theses and Dissertations

The classification of pollen grains is a main task in many disciplines including ecology, forensic sciences, allergy control, and oil exploration. In these application areas, visual inspection is the common method used for classifying pollen. However, recognition by visual inspection consumes much time and effort. Even though some level of automation exists, the automatic recognition of pollen grains remains an open problem. Current pollen-classification solutions rely on measurements of visual cues such as contour or texture. However, these features do not capture the visual complexity of information needed for discriminating among various species of pollen, especially when both a large-scale …

Design And Optimization Of A Passive Magnetic Thrust Bearing, Thomas Matthew Lasko

Theses and Dissertations

High-speed turbomachines present a number of unique challenges and problems. Large centrifugal forces create high stresses in rotating components, friction leads to elevated temperatures and component failure, and rotordynamic instability makes control difficult. The weak link in these high-speed systems is often the bearings because they provide the interface between the rotating and stationary components. Traditional bearings often fail in these conditions, especially when relatively large force capacities are required. In miniature gas turbines for unmanned aerial vehicle (UAV) applications, traditional bearings exhibit a typical lifetime of only 25 hours due to excessive axial loading. This research presents a passive …

Development Of Recyclability Index: A Design For Assembly And Disassembly Approach, Darshan Yadav

Theses and Dissertations

Designing products for recyclability is driven by environmental and economic goals. Several Design for Assembly(DFA) rules and parameters can be used to gauge the recyclability index of product designs. These indices can be used for comparative analysis of the recyclability of different products. This assists the designer in making design choices related to the product’s end of life. However, many of the existing recyclability indices are only available after design and manufacturing decisions are made. If such design decisions could be made earlier in the design process, when the design space is less bound, recyclability could be considered earlier. A …

Risk Analysis Of Autonomous Vehicle And Its Safety Impact On Mixed Traffic Stream, Plaban Das

Theses and Dissertations

In 2016, more than 35,000 people died in traffic crashes, and human error was the reason for 94% of these deaths. Researchers and automobile companies are testing autonomous vehicles in mixed traffic streams to eliminate human error by removing the human driver behind the steering wheel. However, recent autonomous vehicle crashes while testing indicate the necessity for a more thorough risk analysis. The objectives of this study were (1) to perform a risk analysis of autonomous vehicles and (2) to evaluate the safety impact of these vehicles in a mixed traffic stream. The overall research was divided into two phases: …

Adaptive Control For Inflatable Soft Robotic Manipulators With Unknown Payloads, Jonathan Spencer Terry

Theses and Dissertations

Soft robotic platforms are becoming increasingly popular as they are generally safer, lighter, and easier to manufacture than their more rigid, heavy, traditional counterparts. These soft platforms, while inherently safer, come with significant drawbacks. Their compliant components are more difficult to model, and their underdamped nature makes them difficult to control. Additionally, they are so lightweight that a payload of just a few pounds has a significant impact on the manipulator dynamics. This thesis presents novel methods for addressing these issues. In previous research, Model Predictive Control has been demonstrably useful for joint angle control for these soft robots, using …

A Definition And Demonstration Of Developable Mechanisms, Trent Karl Zimmerman

Theses and Dissertations

There is an increasing need for compact mechanical systems that can accomplish sophisticated tasks. Technologies like ortho-planar and lamina emergent mechanisms (LEMs) have been developed to satisfy needs like these by stowing in planar sheets from which they emerge to perform their function. They can be compact, lightweight, monolithic, scalable, and can withstand harsh environments. They are limited, however, by their base element---planar surfaces. Applications requiring these advantages often include curved surfaces, like aircraft wings, needles, and automotive bodies. In this research, developable mechanisms are presented as a solution to satisfy the need for mechanisms that can conform to or …

Nonlinear Model Predictive Control For A Managed Pressure Drilling With High-Fidelity Drilling Simulators, Junho Park

Theses and Dissertations

The world's energy demand has been rapidly increasing and is projected to continue growing for at least the next two decades. With increasing global energy demand and competition from renewable energy, the oil and gas industry is striving for more efficient petroleum production. Many technical breakthroughs have enabled the drilling industry to expand the exploration to more difficult drilling such as deepwater drilling and multilateral directional drilling. For example, managed pressure drilling (MPD) offers ceaseless operation with multiple manipulated variables (MV) and wired drill pipe (WDP) provides two-way, high-speed measurements from bottom hole and along-string sensors. These technologies have maximum …

Using Collapsible Systems To Mitigate Buckling In Thin Flexible Instruments In Robotic Surgery, Brandon Scott Sargent

Theses and Dissertations

Robotic surgery procedures may include long, thin flexible instruments that are inserted by the robot into the patient. As the robot inserts these devices, due to their geometry, they are prone to buckling failure. To mitigate buckling failure, a support system is needed on the robot. This system supports the device but also adapts to the varying ex vivo length of the device as it is inserted. This work presents four collapsible support systems designed to mitigate buckling failure of long, thin instruments while accounting for changing length. The Ori-Guide is an origami-inspired system that has enabled a part reduction …

Large-Scale Strength Testing Of High-Speed Railway Bridge Embankments: Effects Of Cement Treatment And Skew Under Passive Loading, Daniel Ethan Schwicht

Theses and Dissertations

To investigate the passive force-displacement relationships provided by a transitional zoned backfill consisting of cement treated aggregate (CTA) and compacted gravel, a series of full-scale lateral abutment load tests were performed. The transitional zoned backfill was designed to minimize differential settlement adjacent to bridge abutments for the California High Speed Rail project. Tests were performed with a 2-D or plane strain backfill geometry to simulate a wide abutment. To investigate the effect of skew angle on the passive force, lateral abutment load tests were also performed with a simulated abutment with skew angles of 30º and 45º. The peak passive …