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Electronic Theses and Dissertations

2011

The University of Maine

Articles 1 - 11 of 11

Full-Text Articles in Physical Sciences and Mathematics

Synthesis And Characterization Of Catalysts For The Selective Transformation Of Biomass-Derived Materials, Isaac Tyrone Ghampson Dec 2011

Synthesis And Characterization Of Catalysts For The Selective Transformation Of Biomass-Derived Materials, Isaac Tyrone Ghampson

Electronic Theses and Dissertations

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silicasupported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, …

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Event Discovery And Classification In Space-Time Series: A Case Study For Storms, Avinash Rude May 2011

Event Discovery And Classification In Space-Time Series: A Case Study For Storms, Avinash Rude

Electronic Theses and Dissertations

Recent advancement in sensor technology has enabled the deployment of wireless sensors for surveillance and monitoring of phenomenon in diverse domains such as environment and health. Data generated by these sensors are typically high-dimensional and therefore difficult to analyze and comprehend. Additionally, high level phenomenon that humans commonly recognize, such as storms, fire, traffic jams are often complex and multivariate which individual univariate sensors are incapable of detecting. This thesis describes the Event Oriented approach, which addresses these challenges by providing a way to reduce dimensionality of space-time series and a way to integrate multivariate data over space and/or time …

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Exfoliated Graphite Nanoplatelet-Filled Impact Modified Polypropylene Nanocomposites, Alex Duguay May 2011

Exfoliated Graphite Nanoplatelet-Filled Impact Modified Polypropylene Nanocomposites, Alex Duguay

Electronic Theses and Dissertations

Exfoliated graphite nanoplatelets (xGnP)-filled polymer composites have demonstrated superior electrical, mechanical, physical and thermal properties and are becoming a major focus for both academic and industrial research and development (R&D) activities. The main objective of this study was to characterize the influence of xGnP particle diameter, filler loading and the addition of coupling agents on the mechanical, rheological and thermal properties of xGnP-filled impact modified polypropylene (IMPP) composites. IMPP is currently being used at the AEWC Advanced Structures and Composites Center in polymer impregnated (pre-preg) fiber reinforced polymer (FRP) tapes consisting of an IMPP matrix polymer and E-glass continuous fibers. …

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Interannual Variability In American Lobster Settlement: Correlations With Sea Surface Temperature, Wind Stress And River Discharge, Mahima Jaini May 2011

Interannual Variability In American Lobster Settlement: Correlations With Sea Surface Temperature, Wind Stress And River Discharge, Mahima Jaini

Electronic Theses and Dissertations

Recruitment to benthic marine populations is fundamentally a biophysical problem. The American Lobster Settlement Index is an annual diver-based survey of the young-of-year American lobsters (Homarus americanus) found in inshore nurseries in New England, USA and Atlantic Canada at the end of the postlarval settlement season. The considerable interannual variability in the settlement index suggests that environmental factors play an important role in regulating planktonic larval supply and transport. In this study, I focused on the longest settlement time series from three oceanographically contrasting regions: Midcoast Maine, coastal Rhode Island and the lower Bay of Fundy. Sampling in these regions …

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Photonic Non-Destructive Measurement Methods For Investigating The Evolution Of Polar Firn And Ice, Daniel James Breton Jan 2011

Photonic Non-Destructive Measurement Methods For Investigating The Evolution Of Polar Firn And Ice, Daniel James Breton

Electronic Theses and Dissertations

When snow falls on glaciers or ice sheets, it persists for many tens, hundreds and sometimes thousands of years before becoming ice. The granular material in between fresh snow and glacial ice is known as firn and is generally 50 to 100 m thick over polar ice sheets. The compaction mechanism of firn into ice (called densification) has important glaciological ramifications in determination of ice sheet stability and related sea level rise effects via remote sensing altimetry. Firn densification is also important for correctly interpreting ice core paleoclimate records, especially those analyzing gases trapped in air bubbles within the glacial …

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Late-Pleistocene Glacial And Climate Fluctuations In The Torres Del Paine Region (51ºs), Southern South America, Juan Luis Garcia Jan 2011

Late-Pleistocene Glacial And Climate Fluctuations In The Torres Del Paine Region (51ºs), Southern South America, Juan Luis Garcia

Electronic Theses and Dissertations

Variations in Earth‘s orbital parameters affect insolation and are thought to drive ice-age cycles (Milankovitch Theory). Northern and southern mid-latitudes show opposing insolation signals, because of the effect of precession. Despite this difference, paleoclimate records from both hemispheres display broadly synchronous glacialinterglacial climate changes tied to northern hemisphere insolation. This would imply that southern hemisphere glaciers advanced in the face of increasing local summer insolation during the last glacial maximum and thus raises questions about the orbital theory of ice ages. Well-dated paleoclimate records are important for testing hypotheses concerning the origin of ice ages, particularly in the southern hemisphere. …

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Electronic Transport Properties Of Ruthenium And Ruthenium Dioxide Thin Films, Michael M. Steeves Jan 2011

Electronic Transport Properties Of Ruthenium And Ruthenium Dioxide Thin Films, Michael M. Steeves

Electronic Theses and Dissertations

Resistivities (ρ) and Hall coefficients (RH) of polycrystalline Ru and RuO2 thin films were measured from 293 to 600 K in vacuum, O2, and CO. Differing nanostructures and textures were sputtered at normal, confocal, and glancing incidences to 20 - 300 nm thickness. For Ru in planar or nanorod morphologies, defects have negligible effect on RH, which is similar to RH in bulk metal. Models of effective thickness are derived for the nanorod morphology. For Ru and RuO2 films, decreases in ρ on first heating are caused by defect annealing; subsequent …

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Identifying And Addressing Specific Student Difficulties In Advanced Thermal Physics, Trevor I. Smith Jan 2011

Identifying And Addressing Specific Student Difficulties In Advanced Thermal Physics, Trevor I. Smith

Electronic Theses and Dissertations

As part of an ongoing multi-university research study on student understanding of concepts in thermal physics at the upper division, I identified several student difficulties with topics related to heat engines (especially the Carnot cycle), as well as difficulties related to the Boltzmann factor. In an effort to address these difficulties, I developed two guided-inquiry worksheet activities (a.k.a. tutorials) for use in advanced undergraduate thermal physics courses. Both tutorials seek to improve student understanding of the utility and physical background of a particular mathematical expression. One tutorial focuses on a derivation of Carnot's theorem regarding the limit on thermodynamic efficiency, …

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High Resolution Antarctic Glaciochemical Climate Proxy Records And Their Global Implications, Daniel Arthur Dixon Jan 2011

High Resolution Antarctic Glaciochemical Climate Proxy Records And Their Global Implications, Daniel Arthur Dixon

Electronic Theses and Dissertations

The first section of this study presents major ion, trace element, heavy metal, rare earth element and oxygen isotope data from a series of surface snow samples and shallow firn sections collected along four US ITASE traverses across extensive regions of East and West Antarctica. In each sample the dissolved major ion, total trace element, and d18O concentrations are measured. This provides a baseline from which changes in the chemistry of the atmosphere over Antarctica can be monitored under expected warming scenarios and continued intensification of industrial activities in the Southern Hemisphere. Satellite remote sensing measurements of microwave backscatter and …

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Crenulation Cleavage Development And The Influence Of Rock Microstructure On Crustal Seismic Anisotropy, Felice Maria Johanna Naus-Thijssen Jan 2011

Crenulation Cleavage Development And The Influence Of Rock Microstructure On Crustal Seismic Anisotropy, Felice Maria Johanna Naus-Thijssen

Electronic Theses and Dissertations

This thesis investigates the cause of mass transfer during crenulation cleavage formation and the role that elastically anisotropic minerals and fabric development play in promoting seismic anisotropy in the crust. Crenulation cleavage is the most common fabric in multiplydeformed, phyllosilicate-rich metamorphic rocks. During its formation the originally planar fabric gets crenulated, eventually leading to the differentiation of quartz- and feldspar-rich regions (QFdomains) in the crenulation hinges, and phyllosilicate-rich regions (P-domains) in the crenulation limbs. This differentiation is driven by the dissolution of quartz and feldspar in the P-domains, and the precipitation of those minerals in the QF-domains. Finite element models …

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The Extended Kalman-Consensus Filter, Andrew Pellett Jan 2011

The Extended Kalman-Consensus Filter, Andrew Pellett

Electronic Theses and Dissertations

An algorithm called the extended Kalman-Consensus filter is developed as an extension of the Kalman-Consensus filter to the non-linear case. The extended Kalman- Consensus filter is a technique for estimating the state of a non-linear process disturbed by noise using multiple observations from a distributed set of sense nodes. All sense nodes attempt to estimate the same state by determining how their observations affect that state, and by communicating with neighbor nodes. The algorithm is designed to be more accurate through measurement diversity, scalable to a large number of nodes, and robust against loss of nodes during operation. Simulations are …

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