Physical Sciences and Mathematics Commons^™

Uncommon Numerical Instability In The Method Of Characteristic Applied To Hyperbolic Equations, Zihao Deng

Graduate College Dissertations and Theses

This thesis presents the stability analysis of the numerical method of characteristic (MoC) that is applied to hyperbolic partial differential equations (PDEs). Simple Euler method, Modified Euler method and Leapfrog method are used for numerical integration along the characteristics. The corresponding MoC schemes are referred to as MoC-SE, MoC-ME, and MoC-LF respectively.

We discovered and explained two unusual phenomena. First, certain non-periodic boundary condition (b.c.) could eliminate the numerical instability for some schemes such as the MoC-ME, where the instability exists for periodic b.c. However, it is commonly believed that

if von Neumann analysis, i.e., assuming periodic b.c., predicts numerical …

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 …

The Impacts Of Climate Change On Precipitation And Hydrology In The Northeastern United States, Justin Guilbert

Graduate College Dissertations and Theses

Shifting climatic regimes can increase or decrease the frequency of extreme hydrologic events (e.g., high and low streamflows) causing large societal and environmental impacts. The impacts are numerous and include human health and safety, the destruction of infrastructure, water resources, nutrient and sediment transport, and within stream ecological health. It is unclear how the hydrology of a given region will shift in response to climate change. This is especially the case in areas that are seasonally snow covered as the interplay of changing temperature, precipitation, and resulting snowpack can lead to an increased risk of flood or drought.

This research …

Ecological Dynamics In Compost-Amended Soils And The Resulting Effects On Escherichia Coli Survival, Anya Cutler

Graduate College Dissertations and Theses

Escherichia coli (E. coli) are common and typically innocuous copiotrophic bacteria found in the mammalian gut microbiome. However, over the past 30 years, pathogenic E. coli have been responsible for several outbreaks of foodborne illness linked to contaminated produce. The introduction of Escherichia coli to an agricultural soil, via contaminated water, compost, or raw manure, exposes the bacterium to a medley of ecological forces not found in a mammalian gut environment. This study assesses a variety of abiotic and biotic soil factors that influence the ability of an "invasive" copiotrophic coliform bacterium to survive in compost-amended agricultural soil. The study …

Importance Of Agricultural Systems As Multifunctional Landscapes, Flavio Sutti

Graduate College Dissertations and Theses

Agricultural landscapes provide our society with many benefits. While food production is the primary role of these landscapes, sociocultural and ecological benefits are also provided. However, the full scope of benefits that we obtain from agricultural landscapes are not always taken into account, and with the intensification of agricultural activities, more complex multifunctional landscapes are converted into simpler and less-functional landscapes. I used a heterogeneous agricultural landscape, the Champlain Valley of Vermont, as a case study to examine the interactions between landscape structure and the provision of landscape functions and services.

I analyzed sociocultural and production functions indices obtained via …

A Genetic Programming Approach To Cost-Sensitive Control In Wireless Sensor Networks, Afsoon Yousefi Zowj

Graduate College Dissertations and Theses

In some wireless sensor network applications, multiple sensors can be used to measure the same variable, while differing in their sampling cost, for example in their power requirements. This raises the problem of automatically controlling heterogeneous sensor suites in wireless sensor network applications, in a manner that balances cost and accuracy of sensors. Genetic programming (GP) is applied to this problem, considering two basic approaches. First, a hierarchy of models is constructed, where increasing levels in the hierarchy use sensors of increasing cost. If a model that polls low cost sensors exhibits too much prediction uncertainty, the burden of prediction …

Unprecedented Ractivity Of 1-Aza-2-Azoniaallene Salts: New Methodologies And Mechanistic Studies For The Formation Of Diazenium Salts And Tetrahydropyridazines, Nezar Al-Bataineh

Graduate College Dissertations and Theses

This thesis describes the research conducted towards the overall goal of developing new synthetic organic methods to facilitate the synthesis of structurally complex nitrogen-containing polycyclic compounds. More specifically, I will describe the diverse reactivity of 1-aza-2-azoniaallene systems to make polycyclic diazenium salts and tetrahydropyridazine rings. I will also describe mechanistic studies undertaken to better understand this reactivity.

The Brewer research group has discovered that hydrazones undergo an oxidation reaction with chlorodimethylsulfonium chloride to afford -chloroazo compounds, which react intramolecularly with pendent alkene units to give bicyclic ring fused and bridged diazenium salts. My work includes a mechanistic study to understand …

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 …

Evaluating Stormwater Pollutant Removal Mechanisms By Bioretention In The Context Of Climate Change, Amanda Cording

Graduate College Dissertations and Theses

Stormwater runoff is one of the leading causes of water quality impairment in the U.S. Bioretention systems are ecologically engineered to treat stormwater pollution and offer exciting opportunities to provide local climate change resiliency by reducing peak runoff rates, and retaining/detaining storm volumes, yet implementation is outpacing our understanding of the underlying physical, biological, and chemical mechanisms involved in pollutant removal. Further, we do not know how performance will be affected by increases in precipitation, which are projected to occur in the northeastern U.S. as a result of climate change, or if these systems could act as a source or …

Edge-Of-Field Water And Phosphorus Losses In Surface And Subsurface Agricultural Runoff, Laura B. Klaiber

Graduate College Dissertations and Theses

Quantifying effectiveness of soil management practices on surface and subsurface water quality at the field scale is becoming increasingly important in the Lake Champlain Basin and other agricultural watersheds. During 2012 and 2013, field plots (22.9 x 45.7 m) were established at the Lake Alice Wildlife Area in Chazy, NY to begin a long-term water quality monitoring study. Plots were established in a cool season grass field (1 ha) leased and managed by the William H. Miner Agricultural Research Institute in Chazy, NY. The soil type transitions from an excessively drained outwash soil on the upslope to a very poorly …

Invasive Plant Ecology In Vermont: Insights From Spatial Analysis And Interactions Of Garlic Mustard (Alliaria Petiolata) With Native Plants And Invertebrates, Chenin Kathleen Limback

Graduate College Dissertations and Theses

Causes and patterns of invasive plant species establishment and success depend broadly upon their ecology, including habitat suitability and interactions with other plants and animals. Here I examine the traits and distribution of invasive plants in Vermont, using spatial analysis, laboratory and field studies. I used GIS to investigate environmental factors correlated with presence of 19 invasive plant species in Vermont campgrounds. My results support the assumption that human dispersal of invasive plant seed and stock may be more important than natural dispersal of these plant species to new sites. I also investigate in-depth the relationships of invasive herbaceous garlic …

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 …

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 …

Impacts Of Forest Disturbance On Small Mammal Distribution, Allyson Lenora Degrassi

Graduate College Dissertations and Theses

Natural habitat in the eastern United States has diminished over the past century because of the effects of invasive species. Both plant and animal invaders can alter habitat structure and may decrease survival of native species. The degree to which an invasive species alters ecosystem function depends on the functional characteristics of affected species and the resulting cascading effects. The loss of important native species, such as foundation species, can potentially influence the structure and distribution of animal communities because of the foundation species' unique ecosystem roles. The foundation species concept is relatively new to the terrestrial ecology and the …

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, …

Quantifying Soil Greenhouse Gas Emissions And Soil Carbon Storage To Determine Best Management Practices In Agroecosystems, Tyler Goeschel

Graduate College Dissertations and Theses

Intensive agriculture, coupled with an increase in nitrogen fertilizer use, has contributed significantly to the elevation of atmospheric greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Rising GHG emissions usually mean a decrease in soil carbon. Currently, soil C is twice that of all standing crop biomass, making it an extremely important player in the C cycle. Fortunately, agricultural management practices have the potential to reduce agricultural GHG emissions whilst increasing soil C. Management practices that impact GHG emissions and soil C include various tillage practices, different N fertilization amounts and treatments (synthetic N, cattle …

Oxygen-Sensitive Luminophores: A Survey Of The Literature And Efforts Toward A Novel Porphyrin-Pillared Zirconium Phosphonate, Joseph Wright

Graduate College Dissertations and Theses

Measurement and mapping of the pressure distribution across the surface of a suitably scaled model is an integral step in the design of any aircraft or automobile. For this purpose, the traditional workhorses of the aeronautic and automotive industries have been pressure taps--small orifices that contain electronic pressure transducers. Unfortunately, in addition to the limited spatial resolution achievable with such devices, their technical complexity and cost constitute serious disadvantages. For more than 35 years, researchers have pursued a fundamentally different alternative: indirect measurement of pressure via oxygen-induced quenching of the luminescence emitted by certain chemical species. Porphyrin complexes of dipositive …

Using Aqueous Soil Extracts To Study Organic Matter Leaching From Soils Of Different River Corridor Land Covers In Vermont, Alyson Hampsch

Graduate College Dissertations and Theses

Soils represent an important terrestrial carbon (C) sink, storing up to three times the amount of atmospheric C, however climate and land use changes may transform soils into C sources. River corridor (RC) soils and associated C are at risk to become mobilized by erosion such as bank failure and scour events. Once soil-derived organic C is transferred into the stream, microbial processes and photodegradation of the dissolved, labile (or bioavailable) fractions can lead to the production of CO2, which can evade and increase atmospheric CO2 levels. Because predicted increases in heavy precipitation will likely increase this type of riverine …

Measurement And Modeling Of Stormwater From Small Suburban Watersheds In Vermont, Joel Nipper

Graduate College Dissertations and Theses

Despite decades of U.S. water quality management efforts, over half of assessed waterbody units were threatened or impaired for designated uses in the most recent assessments, with urban runoff being a leading contributor to those impairments. This cumulative research explores several aspects of urban runoff dynamics through a combination of field study and modeling.

Stormwater ponds are ubiquitous in developed landscapes due to their ability to provide multiple forms of treatment for stormwater runoff. However, evolving design goals have reduced the applicability of much of the early work that was done on pond effectiveness. In this study, we instrumented 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 …

Placing Natural Resource Decisions In Social And Historical Contexts: Sociological Inquiries Into Agency Communications, Management Rationalities, And Community Change, Emilian Geczi

Graduate College Dissertations and Theses

A sociological understanding of natural resource management decisions traces the links between historical change (How does this historical period differ from other periods?), society (What social relations exist at this time and how do they persist or change?), and individuals (What types of conduct and discourse prevail in this society and in this period?). The papers submitted for this dissertation examine the connections between identity, social milieu, and historical change relative to three resource management issues:

(1) The promotion of nature play areas as a novel landscape form. Analysis of agency materials suggests that these spaces are advertised as bucolic …

The Relationship Between Magmatism And Deformation During The Acadian Orogeny: A Case Study From Eastern-Central Vermont, Samuel William Lagor

Graduate College Dissertations and Theses

The Silurian-Devonian metasedimentary rocks of the Connecticut Valley-Gaspé trough (CVGT) were subjected to multiple deformational and metamorphic events during the Acadian orogeny in the Middle-Late Devonian. Plutons intruding the Devonian Waits River and Gile Mountain Formations have been considered post-tectonic, but microstructural studies of the intrusions and their metamorphic aureoles indicate some of these plutons intruded syntectonically. This study investigates the relationship between Acadian deformation and intrusion of the Knox Mountain pluton (KMP) of central Vermont. Structural and geochronological data were collected along a c. 15 km transect from the western limit of the CVGT, where the unconformable Richardson Memorial …

Polarization Charge Density In Strained Graphene, Noah Wilson

Graduate College Dissertations and Theses

Graphene, the world's first truly two-dimensional material, is unique for having an electronic structure described by an effective Lorentz invariant theory. One important consequence is that the ratio or Coulomb energy to kinetic energy is a constant, depending only on conditions within the lattice rather than on the average charge density as in a typical Galilean invariant material. Given this unusual property, a natural question would be how do phenomena, such as screening of a Coulomb impurity, happen in graphene? Moreover, how does the addition of uniaxial strain enhance or diminish this behavior? Here I discuss our work to calculate …

Enabling Machine Science Through Distributed Human Computing, Mark David Wagy

Graduate College Dissertations and Theses

Distributed human computing techniques have been shown to be effective ways of accessing the problem-solving capabilities of a large group of anonymous individuals over the World Wide Web. They have been successfully applied to such diverse domains as computer security, biology and astronomy. The success of distributed human computing in various domains suggests that it can be utilized for complex collaborative problem solving. Thus it could be used for "machine science": utilizing machines to facilitate the vetting of disparate human hypotheses for solving scientific and engineering problems.

In this thesis, we show that machine science is possible through distributed human …

Establishing Chemical Mechanisms And Estimating Phase State Of Secondary Organic Aerosol From Atmospherically Relevant Organic Precursors, Shashank Jain

Graduate College Dissertations and Theses

Organic aerosol (OA) is a ubiquitous component of atmospheric particulate that influences both human health and global climate. A large fraction of OA is secondary in nature (SOA), being produced by oxidation of volatile organic compounds (VOCs) emitted by biogenic and anthropogenic sources. Despite the integral role of SOA in atmospheric processes, there remains a limited scientific understanding of the chemical and physical changes induced in SOA as it ages in the atmosphere. This thesis describes work done to increase the knowledge of processes and properties of atmospherically relevant SOA.

In the work presented in this thesis, I have worked …

Second Coordination Sphere Of Heme In Mycobacterium Tuberculosis Mhud, And The Mechanism Of Heme Degradation, Amanda Graves

Graduate College Dissertations and Theses

MhuD is a heme degrading enzyme from Mycobacterium tuberculosis that catalyzes both monooxygenation and dioxygenation leading to novel chromophores, mycobilins. The X-ray crystal structure of heme-bound, cyanide-inhibited MhuD displays a ruffled heme substrate where pyrrole rings are rotated around the Fe-N bonds, distorting the heme. The electronic structure of the heme in heme-bound, cyanide-inhibited MhuD (MhuD-heme-CN) is characterized here to provide insight into the mechanism of heme degradation by MhuD. Analysis of nuclear magnetic resonance (NMR) and magnetic circular dichroism (MCD) data for MhuD-heme-CN leads to the conclusion that the ground, (dxz,yz)4(dxy)1 electron configuration (2B2g state) and excited (dxy)2(dxz,yz)3 electron …

The Structural Evolution Of A Portion Of The Median Batholith And Its Host Rock In Central Fiordland, New Zealand: Examples Of Partitioned Transpression And Structural Reactivation, Hannah Jane Blatchford

Graduate College Dissertations and Theses

This thesis presents the results of structural analyses and detailed field mapping from a region near Adams Burn in central Fiordland, New Zealand. The region preserves assemblages of metasedimentary and metaigneous rocks deposited, intruded, and ultimately metamorphosed and deformed during the growth of a Gondwana-margin continental arc from Cambrian-Early Cretaceous. Evidence of arc growth is preserved in the Late Devonian-Early Cretaceous Median Batholith, a belt of intrusive rock whose growth culminated with the emplacement of the Western Fiordland Orthogneiss (WFO) into the middle-lower crust of the margin. Following this magmatic flare-up, the margin experienced Late Cretaceous extensional orogenic collapse and …

Master's Project - Solar Farming In Vermont - What's The Harvest?, Sam Carlson

Rubenstein School Masters Project Publications

An operational research project to investigate net economic, environmental and public policy benefits from converting land from agriculture to solar electricity generation was undertaken on a 15-acre farm in Proctor, Vermont. Two solar arrays (66 KW AC and 500 KW AC) were established.

The net after-tax financial return on cash equity of the 66 KW AC solar project was calculated to be 21% for the investor over a 25-year period (less than 1% average annual rate of return), while the financial return for the 500 KW AC solar project was 145% over a similar period (5.8% average annual rate of …

Integrating Management For Old-Growth Characteristics With Enhanced Carbon Storage Of Northern Hardwood-Conifer Forests, Sarah Eliot Ford

Graduate College Dissertations and Theses

Forest management practices emphasizing stand structural complexity are of interest across the northern forest region of the United States because of their potential to enhance carbon storage. Our research is nested within a long-term study evaluating how silvicultural treatments promoting late-successional forest characteristics affect aboveground biomass development in northern hardwood forests. We are testing the hypothesis that biomass development (carbon storage) will be greater in structural complexity enhancement (SCE) treatments when compared to conventional uneven-aged treatments. SCE treatments were compared against selection systems (single-tree and group) modified to retain elevated structure. Manipulations and controls were replicated across 2-hectare treatment units …

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 …