Engineering Commons^™

A Mechanistically Guided Approach To Treatment Of Multi-Wavelet Reentry: Experiments In A Computational Model Of Cardiac Propagation, Richard T. Carrick

Graduate College Dissertations and Theses

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the United States today. However, treatment options remain limited despite the enormous magnitude of both AF prevalence and the associated economic cost. Of those treatment options that are available, ablation-based interventional methods have demonstrated the highest rates of long-term cure. Unfortunately, these methods have substantially lower efficacy in patients with heavier burdens of disease, thus leaving the most affected individuals with the least hope for successful treatment.

The focus of this research is to develop a mechanistically guided approach towards the treatment of multi-wavelet reentry (MWR), one of the primary …

Evaluation Of The Engine Exhaust Particle Sizer (Eeps) For Real-Time Measurements Of Diesel And Biodiesel Exhaust Particulate Matter, James Robert Dunshee

Graduate College Dissertations and Theses

Even at low concentrations, the criteria air pollutant particulate matter (PM) is an environmental and public health hazard. Emissions levels legislated for modern diesel vehicles are so low (~90% lower than 2003) that it has become difficult to accurately measure PM by the regulatory metric: the mass of particles collected on a filter (i.e., the gravimetric method). Additionally, gravimetric analysis cannot measure real-time emission rates, and therefore is unable to characterize high-emitting transient events (e.g., engine starts, stop-and-go driving). By an alternate method, PM can be estimated by measuring the number-weighted particle size distribution (PSD) and calculating mass with a …

An Alternative Sensor Fusion Method For Object Orientation Using Low-Cost Mems Inertial Sensors, Joshua Lee Bouffard

Graduate College Dissertations and Theses

This thesis develops an alternative sensor fusion approach for object orientation using low-cost MEMS inertial sensors. The alternative approach focuses on the unique challenges of small UAVs. Such challenges include the vibrational induced noise onto the accelerometer and bias offset errors of the rate gyroscope. To overcome these challenges, a sensor fusion algorithm combines the measured data from the accelerometer and rate gyroscope to achieve a single output free from vibrational noise and bias offset errors.

One of the most prevalent sensor fusion algorithms used for orientation estimation is the Extended Kalman filter (EKF). The EKF filter performs the fusion …

Cascading Failure Risk Estimation And Mitigation In Power Systems, Pooya Rezaei

Graduate College Dissertations and Theses

Electricity is a critical component in our daily life. Because it is almost always available, we take it for granted. However, given the proper conditions, blackouts do happen every once in a while and can cause discomfort at a minimum, and a catastrophe in rare circumstances. The largest blackouts typically include cascading failures, which are sequences of interdependent outages. Although timely and effective operator intervention can often prevent a cascade from spreading, such interventions require ample situational awareness.

The goals of this dissertation are twofold: to provide power system operators with insight into the risk of blackouts given the space …

Reviewing Power Outage Trends, Electric Reliability Indices And Smart Grid Funding, Shawn Adderly

Graduate College Dissertations and Theses

As our electric power distribution infrastructure has aged, considerable investment

has been applied to modernizing the electrical power grid through weatherization

and in deployment of real-time monitoring systems. A key question is whether or not

these investments are reducing the number and duration of power outages, leading to

improved reliability.

Statistical methods are applied to analyze electrical disturbance data (from the

Department of Energy, DOE) and reliability index data (from state utility public service

commission regulators) to detect signs of improvement. The number of installed

smart meters provided by several utilities is used to determine whether the number

of smart …

Development Of A Physical And Electronic Model For Ruo2 Nanorod Rectenna Devices, Justin Dao

Graduate College Dissertations and Theses

Ruthenium oxide (RuO2) nanorods are an emergent technology in nanostructure devices. As the physical size of electronics approaches a critical lower limit, alternative solutions to further device miniaturization are currently under investigation. Thin-film nanorod growth is an interesting technology, being investigated for use in wireless communications, sensor systems, and alternative energy applications.

In this investigation, self-assembled RuO2 nanorods are grown on a variety of substrates via a high density plasma, reactive sputtering process. Nanorods have been found to grow on substrates that form native oxide layers when exposed to air, namely silicon, aluminum, and titanium. Samples were analyzed with Scanning …

Zero-Group-Velocity Propagation Of Electromagnetic Wave Through Nanomaterial, Taian Fan

Graduate College Dissertations and Theses

This research will investigate the problem on the propagation of electromagnetic wave through a specific nanomaterial. The nanomaterial analyzed is a material consisting of a field of Pt nanorods. This field of Pt nanorods are deposited on a substrate which consists of a RuO2 nano structure. When the nanorod is exposed to an electron beam emitted by a TEM (Transmission electron microscopy). A wave disturbance has been observed. A video taken within the chamber shows a wave with a speed in the scale of um/s (Á?10Á?^(-6) m/s), which is 14 orders of magnitude lower than speed of light in free …

Renewable Energy Transition: Dynamic Systems Analysis, Policy Scenarios, And Trade-Offs For The State Of Vermont, Christopher Ernest Clement

Graduate College Dissertations and Theses

There is broad consensus that a transition to renewable energy and a low-carbon economy is crucial for future development and prosperity, yet there are differing perspectives on how such a transition should be achieved. The overarching goal of this dissertation, which is comprised of three interrelated studies, is to analyze and compare energy futures scenarios to achieve a renewable energy transition and low-carbon economy in the State of Vermont. In the first study, an analysis is presented of the role of energy pricing regimes and economic policy in the context of pursuing a renewable energy transition in the State of …

Two-Dimensional Numerical Study Of Micronozzle Geometry, Jason M. Pearl

Graduate College Dissertations and Theses

Supersonic micronozzles operate in the unique viscosupersonic flow regime, characterized by large Mach numbers (M>1) and low Reynolds numbers (Re<1000). Past research has primarily focused on the design and analysis of converging-diverging de Laval nozzles; however, plug (i.e. centerbody) designs also have some promising characteristics that might make them amenable to microscale operation. In this study, the effects of plug geometry on plug micronozzle performance are examined for the Reynolds number range Re = 80-640 using 2D Navier-Stokes-based simulations. Nozzle plugs are shortened to reduce viscous losses via three techniques: one - truncation, two - the use of parabolic contours, and three - a geometric process involving scaling. Shortened nozzle are derived from a full length geometry designed for optimal isentropic performance. Expansion ratio (ε = 3.19 and 6.22) and shortened plug length (%L = 10-100%) are varied for the full Reynolds number range. The performance of plug nozzles is then compared to that of linear-walled nozzles for equal pressure ratios, Reynolds numbers, and expansion ratios. Linear-walled nozzle half-angle is optimized to to ensure plug nozzles are compared against the best-case linear-walled design.

Results indicate that the full length plug nozzle delivers poor performance on the microscale, incurring excessive viscous losses. Plug performance is increased by shortening the nozzle plug, with the scaling technique providing the best performance. The benefit derived from reducing plug length depends upon the Reynolds number, with a 1-2% increase for high Reynolds numbers an up to 14% increase at the lowest Reynolds number examined. In comparison to Linear-walled nozzle, plug nozzles deliver superior performance when under-expanded, however, …

The Role Of Uncertainty In Categorical Perception Utilizing Statistical Learning In Robots, Nathaniel V. Powell

Graduate College Dissertations and Theses

At the heart of statistical learning lies the concept of uncertainty.

Similarly, embodied agents such as robots

and animals must likewise address uncertainty, as sensation

is always only a partial reflection of reality. This

thesis addresses the role that uncertainty can play in

a central building block of intelligence: categorization.

Cognitive agents are able to perform tasks like categorical perception

through physical interaction (active categorical perception; ACP),

or passively at a distance (distal categorical perception; DCP).

It is possible that the former scaffolds the learning of

the latter. However, it is unclear whether DCP indeed scaffolds

ACP in humans and …

Modeling The Spatiotemporal Dynamics Of Cells In The Lung, Joshua Jeremy Pothen

Graduate College Dissertations and Theses

Multiple research problems related to the lung involve a need to take into account the spatiotemporal dynamics of the underlying component cells. Two such problems involve better understanding the nature of the allergic inflammatory response to explore what might cause chronic inflammatory diseases such as asthma, and determining the rules underlying stem cells used to engraft decellularized lung scaffolds in the hopes of growing new lungs for transplantation. For both problems, we model the systems computationally using agent-based modeling, a tool that enables us to capture these spatiotemporal dynamics by modeling any biological system as a collection of agents (cells) …

Excitonic States In Crystalline Organic Semiconductors: A Condensed Matter Approach, Lane Wright Manning

Graduate College Dissertations and Theses

In this work, a new condensed matter approach to the study of excitons based on crystalline thin films of the organic molecule phthalocyanine is introduced. The premise is inspired by a wealth of studies in inorganic semiconductor ternary alloys (such as AlGaN, InGaN, SiGe) where tuning compositional disorder can result in exciton localization by alloy potential fluctuations. Comprehensive absorption, luminescence, linear dichroism and electron radiative lifetime studies were performed on both pure and alloy samples of metal-free octabutoxy-phthalocyanine and transition metal octabutoxy-phthalocyanines, where the metal is Mn, Co, Ni, and Cu. Varying the ratios of the metal to metal-free phthalocyanines …

A Study Of The Physicochemical Properties Of Dense And Mesoporous Silica Nanoparticles That Impact Protein Adsorption From Biological Fluids, Alden Michael Clemments

Graduate College Dissertations and Theses

At the intersection of materials chemistry and biology, biomaterials have been successfully employed in an array of medical applications. From diagnostic tools to targeted drug delivery, the modular physical and chemical properties of these materials provide numerous applications. For example, porous nanoparticles have been widely integrated as vehicles to carry chemotherapeutics to localized tumor sites. By encapsulating these cytotoxic compounds within a porous framework, the commonly associated adverse side effects of conventional chemotherapeutics, such as Doxorubicin, have been greatly reduced. One such material, mesoporous silica, has received widespread attention due to its excellent biocompatibility, high surface area to mass ratio, …

A Drift Eliminated Attitude & Position Estimation Algorithm In 3d, Ruoyu Zhi

Graduate College Dissertations and Theses

Inertial wearable sensors constitute a booming industry. They are self contained, low powered and highly miniaturized. They allow for remote or self monitoring of health-related parameters. When used to obtain 3-D position, velocity and orientation information, research has shown that it is possible to draw conclusion about issues such as fall risk, Parkinson disease and gait assessment.

A key issues in extracting information from accelerometers and gyroscopes is the fusion of their noisy data to allow accurate assessment of the disease. This, so far, is an unsolved problem. Typically, a Kalman filter or its nonlinear, non-Gaussian version are implemented for …

A Wide Band Adaptive All Digital Phase Locked Loop With Self Jitter Measurement And Calibration, Bo Jiang

Graduate College Dissertations and Theses

The expanding growth of mobile products and services has led to various wireless communication standards that employ different spectrum bands and protocols to provide data, voice or video communication services. Software deffned radio and cognitive radio are emerging techniques that can dynamically integrate various standards to provide seamless global coverage, including global roaming across geographical regions, and interfacing with different wireless networks. In software deffned radio and cognitive radio, one of the most critical RF blocks that need to exhibit frequency agility is the phase lock loop (PLL) frequency synthesizer. In order to access various standards, the frequency synthesizer needs …

Structure And Dynamics Of Two Flow Fields Used For Particle Deposition Onto And Removal From A Substrate, Adam Green

Graduate College Dissertations and Theses

A series of experimental studies was performed to investigate two separate fluid impingement flow systems intended for removal of particles from a surface or deposition of particles onto a surface. One of these flow systems is generated using a nozzle that incorporates both tilted jets and suction to create what we call a "bounded vortex flow", consisting of an annular swirling jet and a wall-normal vortex with axial upflow into a suction outlet. The other flow system is generated by a combination of acoustic streaming and substrate heating from an ultrasonic source. The primary methods used in the study for …

Development Of An Additively Manufactured Microthruster For Nanosatellite Applications, Kevin Russell Gagne

Graduate College Dissertations and Theses

Next generation small satellites, also known as nanosatellites, have masses significantly lower than traditional satellites. Including the propellant mass, the total mass of a nanosatellite is often in the range of 1 to 4 $kg$. These satellites are being developed for numerous applications related to research, defense, and industry. Since their popularity began in the early 2000's, limitations on the downscaling of propulsion systems has proven to be problematic. Due to this, the vast majority of nanosatellite missions have limited lifespans of 90-120 days in low Earth orbit before they reenter the Earth's atmosphere. Although satellites on this scale have …

Impact Of Acl Injury On Patellar Cartilage Thickness, Ethan Leveillee

Graduate College Dissertations and Theses

ACL injury has been shown to have long-lasting and severe consequences on the different structures of the knee such as the articular cartilage and meniscus. Cartilage thickness changes in particular are indicative of osteoarthritic changes in the tibiofemoral joint. While there has been significant research focused on cartilage changes of the tibia and femur, there has been little work looking at patellar cartilage. The following goals were set forth for this study. First, to establish a robust coordinate system to accurately determine the location and orientation of the patella. Secondly, to determine the effects of ACL injury on patellar cartilage …

Leveraging The Information Content Of Process-Based Models Using Differential Evolution And The Extended Kalman Filter, Lucas Howard

Graduate College Dissertations and Theses

Process-based models are used in a diverse array of fields, including environmental engineering to provide supporting information to engineers, policymakers and stakeholdes. Recent advances in remote sensing and data storage technology have provided opportunities for improving the application of process-based models and visualizing data, but also present new challenges. The availability of larger quantities of data may allow models to be constructed and calibrated in a more thorough and precise manner, but depending on the type and volume of data, it is not always clear how to incorporate the information content of these data into a coherent modeling framework. In …

Factors Influencing Mode Choice For Intercity Travel From Northern New England To Major Northeastern Cities, Sean Patrick Neely

Graduate College Dissertations and Theses

Long-distance and intercity travel generally make up a small portion of the total number of trips taken by an individual, while representing a large portion of aggregate distance traveled on the transportation system. While some research exists on intercity travel behavior between large metropolitan centers, this thesis addresses a need for more research on travel behavior between non-metropolitan areas and large metropolitan centers. This research specifically considers travel from home locations in northern New England, going to Boston, New York City, Philadelphia, and Washington, DC. These trips are important for quality of life, multimodal planning, and rural economies. This research …

Real-Time Strategies For The Deployment Of Wireless Repeaters In Uncharacterized Environments, Andrew Giroux

Graduate College Dissertations and Theses

Modern society relies heavily on communication networks that in turn rely on both wired and wireless infrastructure. This work pertains to scenarios where a group of people or robots need to communicate in an environment where there is no preexisting communications infrastructure. These include sites of emergencies and disasters (e.g., inside burning buildings, search and rescue operations) and unexplored areas on Earth and other planets. Wireless ad hoc or mesh networks offer the ability to keep such entities connected, but they falter when any single entity wishes to leave the developed coverage area. Utilizing mobile repeater nodes can help, but …

A Preliminary Study On The Interfacial Strength Of Red Abalone, Saleh Jaman Alghamdi

Graduate College Dissertations and Theses

Nacre is a hierarchical material found within the tough shells of red abalone. Despite being composed of calcium carbonate, nacre exhibits remarkable mechanical properties resulting from the nanoscale brick-and-mortar structure made from aragonite polygons. The objective of this research is to elucidate the toughening mechanisms associated with the interfacial resistance of red abalone. This was achieved by studying the mechanical behavior of dry nacre under pure shear and tension, and characterizing the associated fracture mechanisms using optical and scanning electron microscopes. Mathematical modeling was applied to further quantify the contribution of protein chains, nano-asperities and shear pillars to interfacial strengths. …

Use Of Sacrificial Embankments To Minimize Bridge Damage From Scour During Extreme Flow Events, Matthew Willi Brand

Graduate College Dissertations and Theses

The leading cause of bridge failure has often been identified as bridge scour, which is generally defined as the erosion or removal of streambed and/or bank material around bridge foundations due to flowing water. These scour critical bridges are particularly vulnerable during extreme flood events, and pose a major risk to human life, transportation infrastructure, and economic sustainability. Climate change is increasing the intensity and persistence of large flow events throughout the world, further straining bridge infrastructure. Retrofitting the thousands of undersized and scour critical bridges to more rigorous standards is prohibitively expensive, and current countermeasures inadequately address the core …

Using Real Time Statistical Data To Improve Long Term Voltage Stability In Stochastic Power Systems, Samuel Chevalier

Graduate College Dissertations and Theses

In order to optimize limited infrastructure, many power systems are frequently operated close to critical, or bifurcation, points. While operating close to such critical points can be economically advantageous, doing so increases the probability of a blackout. With the continued deployment of Phasor Measurement Units (PMUs), high sample rate data are dramatically increasing the real time observability of the power grids. Prior research has shown that the statistics of these data can provide useful information regarding network stability and associated bifurcation proximity. Currently, it is not common practice for transmission and distribution control centers to leverage the higher order statistical …

Investigating The Influence Of Gold Nanoparticles On The Photocatalytic And Catalytic Reactivity Of Porous Tungsten Oxide Microparticles, Daniel P. Depuccio

Graduate College Dissertations and Theses

Tungsten oxide (WO3) is a semiconducting transition metal oxide with interesting electronic, structural, and chemical properties that have been exploited in applications including catalysis, gas sensing, electrochromic displays, and solar energy conversion. Nanocrystalline WO3 can absorb visible light to catalyze heterogeneous photooxidation reactions. Also, the acidity of the WO3 surface makes this oxide a good thermal catalyst in the dehydration of alcohols to various industrially relevant chemicals. This dissertation explores the photocatalytic and thermal catalytic reactivity of nanocrystalline porous WO3 microparticles. Furthermore, investigations into the changes in WO3 reactivity are carried out after modifying the porous WO3 particles with gold …

A Framework For Estimating Nutrient And Sediment Loads That Leverages The Temporal Variability Embedded In Water Monitoring Data, Baxter G. Miatke

Graduate College Dissertations and Theses

Rivers deliver significant macronutrients and sediments to lakes that can vary substantially throughout the year. These nutrient and sediment loadings, exacerbated by winter and spring runoff, impact aquatic ecosystem productivity and drive the formation of harmful algae blooms. The source, extent and magnitude of nutrient and sediment loading can vary drastically due to extreme weather events and hydrologic processes, such as snowmelt or high flow storm events, that dominate during a particular time period, making the temporal component (i.e., time over which the loading is estimated) critical for accurate forecasts. In this work, we developed a data-driven framework that leverages …

Assessment Of Surface-Catalyzedreaction Products From Hightemperature Materials In Plasmas, Luke Daniel Allen

Graduate College Dissertations and Theses

Current simulations of atmospheric entry into both Mars and Earth atmospheres for the design of thermal protections systems (TPS) typically invoke conservative assumptions regarding surface-catalyzed recombination and the amount of energy deposited on the surface. The need to invoke such assumptions derives in part from lack of adequate experimental data on gas-surface interactions at trajectory relevant conditions. Addressing this issue, the University of Vermont's Plasma Test and Diagnostics Laboratory has done extensive work to measure atomic specie consumption by measuring the concentration gradient over various material surfaces. This thesis extends this work by attempting to directly diagnose molecular species production …