Physical Sciences and Mathematics Commons^™

Vapor Synthesis And Thermal Evolution Of Supportless, Metal Nanotubes And Application As Electrocatalysts, Robert William Atkinson

Doctoral Dissertations

One of the major limitations of proton exchange membrane fuel cells (PEMFCs) is the high cost and poor durability of the currently preferred catalyst design, small Pt nanoparticles supported on high surface area carbon (Pt/C). Unsupported, high-aspect ratio nanostructured catalysts, or extended surface catalysts, are a promising paradigm as electrocatalysts for a number of electrochemical reactions. These extended surface catalysts generally exhibit higher specific activities compared to their carbon-supported nanoparticle counterparts that have been ascribed to their unique electronic, surface and structural properties. Extended surface catalysts frequently maintain enhanced durability over supported catalysts during fuel cell operation because they are …

Ion Transport In Polymer Electrolytes, Fei Fan

Doctoral Dissertations

Batteries with superior performance will advance many technologies, such as the field of energy storage and electrochemical devices. Traditional lithium ion batteries based on liquid electrolytes have intrinsic problems such as leaking, dendrite growth, and those problems are associated with fire or even explosion hazard. Extensive efforts have been devoted into the development of solid polymer electrolytes (SPEs), which would not only reduce the size and weight of the batteries, but also solve safety related issues. However, none of current dry SPEs have reached the desired conductivity of 10^-3 [0.001] S/cm at ambient temperature. The ion conductivity is controlled …

The Effects Of Realistic Nuclear Kinetics, Dimensionality, And Resolution On Detonations In Low-Density Type Ia Supernovae Environments, Thomas L. Papatheodore

Doctoral Dissertations

Type Ia supernovae are most likely thermonuclear explosions of carbon/oxygen white dwarves in binary stellar systems. These events contribute to the chemical and dynamical evolution of their host galaxies and are essential to our understanding of the evolution of our universe through their use as cosmological distance indicators. Nearly all of the currently favored explosion scenarios for these supernovae involve detonations. However, modeling astrophysical detonations can be complicated by numerical effects related to grid resolution. In addition, the fidelity of the reaction network chosen to evolve the nuclear burning can alter the time and length scales over which the burning …

Experimental And Ab Initio Computational Study Of Azobenzene And Several Of Its Derivatives, Mohammadreza Rezaee

Doctoral Dissertations

In this dissertation we studied azobenzene and seven of its derivatives experimentally in addition to comprehensive ab initio computational investigation. Gas phase ion chemistry studies sre a rich and important area of chemical physics. We used an energy resolved collision induced dissociation technique to study the chemical bonding of these molecule negative or positive ions. We studied the fragment ions which we have detected in the mass spectrum computationally as well. Doing so we experimentally measured the bond dissociation energies and compared them with those resulting from the quantum chemistry computations. We also performed other experiments such as Raman spectroscopy, …

Nucleosynthesis In Self-Consistent Core-Collapse Supernova Models Using Multidimensional Chimera Simulations, James Austin Harris

Doctoral Dissertations

Observations of nuclear abundances in core-collapse supernova (CCSN) ejecta, highlighted by γ-ray [gamma-ray] observations of the ⁴⁴Ti [titanium-44] spatial distribution in the nearby supernova remnants Cassiopeia A and SN 1987A, allow nucleosynthesis calculations to place powerful constraints on conditions deep in the interiors of supernovae and their progenitor stars. This ability to probe where direct observations cannot makes such calculations an invaluable tool for understanding the CCSN mechanism. Unfortunately, despite knowing for two decades that supernovae are intrinsically multi-dimensional events, discussions of CCSN nucleosynthesis have been predominantly based on spherically symmetric (1D) models, which employ a contrived energy source …

Investigations Into The Tectonics Of Uranian And Saturnian Icy Satellites, Chloe Brett Beddingfield

Doctoral Dissertations

This dissertation reports a range of analyses of tectonic structures on various icy satellites and the implications of these analyses for each satellite’s geologic history. On Miranda, I tested the hypothesis that faults of the Arden Corona boundary and the 340º [degree] Chasma are listric in geometry. A listric fault geometry implies the presence of a subsurface detachment, which likely marked Miranda’s brittle-ductile transition (BDT) at the time of faulting. Results support the hypothesis for the Arden Corona boundary, although not for the 340˚ [degree] Chasma. Using the Arden Corona fault system geometry, the BDT depth, thermal gradient, and heat …

Simulations Of Directed Energy Thrust On Rotating Asteroids, Janelle Griswold, Jonathan Madajian, Isabella Johansson, Krysten Pfau, Philip Lubin, Gary B. Hughes, Aidan Gilkes, Peter Meinhold, Caio Motta, Travis Brashears, Qicheng Zhang

Statistics

Asteroids that threaten Earth could be deflected from their orbits using directed energy to vaporize the surface, as the ejected plume creates a reaction thrust that alters the asteroid’s trajectory. In this situation, a critical issue is the rotation of the asteroid relative to the directed energy beam, as this will reduce the average thrust magnitude and modify the thrust direction. Flux levels required to evaporate surface material depend on the surface material composition, rotation rate, albedo, and thermal and bulk mechanical properties of the asteroid. The observed distribution of asteroid rotation rates is used, along with an estimated range …

Directed Energy Interstellar Propulsion Of Wafersats, Travis Brashears, Philip Lubin, Gary B. Hughes, Kyle Mcdonough, Sebastian Arias, Alex Lang, Caio Motta, Peter Meinhold, Payton Batliner, Janelle Griswold, Qicheng Zhang, Yusuf Alnawakhtha, Kenyon Prater, Jonathan Madajian, Olivia Sturman, Jana Gergieva, Aidan Gilkes, Bret Silverstein

Statistics

In the nearly 60 years of spaceflight we have accomplished wonderful feats of exploration and shown the incredible spirit of the human drive to explore and understand our universe. Yet in those 60 years we have barely left our solar system with the Voyager 1 spacecraft launched in 1977 finally leaving the solar system after 37 years of flight at a speed of 17 km/s or less than 0.006% the speed of light. As remarkable as this is, we will never reach even the nearest stars with our current propulsion technology in even 10 millennium. We have to radically rethink …

Local Phase Control For A Planar Array Of Fiber Laser Amplifiers, Patrick Steffanic, Benjamin T. Johannes, Claudia A. Sison, Gary B. Hughes, Philip Lubin, Peter Meinhold, Johnathan Suen, Hugh O'Neill, Miikka Kangas, Travis Brashears, Qicheng Zhang, Janelle Griswold, Jordan Riley, Caio Motta

Statistics

Arrays of phase-locked lasers have been developed for numerous directed-energy applications. Phased-array designs are capable of producing higher beam intensity than similar sized multi-beam emitters, and also allow beam steering and beam profile manipulation. In phased-array designs, individual emitter phases must be controllable, based on suitable feedback. Most current control schemes sample individual emitter phases, such as with an array-wide beam splitter, and compare to a master phase reference. Reliance on a global beam splitter limits scalability to larger array sizes due to lack of design modularity. This paper describes a conceptual design and control scheme that relies only on …

Stand-Off Molecular Composition Analysis, Gary B. Hughes, Philip Lubin, Peter Meinhold, Hugh O'Neill, Travis Brashears, Qicheng Zhang, Janelle Griswold, Jordan Riley, Caio Motta

Statistics

Composition of distant stars can be explored by observing absorption spectra. Stars produce nearly blackbody radiation that passes through the cloud of vaporized material surrounding the star. Characteristic absorption lines are discernible with a spectrometer, and atomic composition is investigated by comparing spectral observations with known material profiles. Most objects in the solar system—asteroids, comets, planets, moons—are too cold to be interrogated in this manner. Material clouds around cold objects consist primarily of volatiles, so bulk composition cannot be probed. Additionally, low volatile density does not produce discernible absorption lines in the faint signal generated by cold objects. We propose …

Directed Energy Deflection Laboratory Measurements, Travis Brashears, Philip Lubin, Gary B. Hughes, Peter Meinhold, Jonathan Suen, Payton Batliner, Caio Motta, Janelle Griswold, Miikka Kangas, Isabella Johansson, Yusuf Alnawakhtha, Kenyon Prater, Alex Lang, Jonathan Madajian

Statistics

We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR and DE-STARLITE are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid’s orbit. In a series of papers, we have developed a theoretical basis …

Using Data Visualization Software To Aid In The Analysis Of Geographical Data, Matthew R. Evers, Inzamam Rahaman

STAR Program Research Presentations

NASA Web World Wind (Web WW) is designed to visualize and manage geographical data. As a first implementation of visualization and analysis, we designed an application to map earthquake data onto the globe. Portions of this code were merged with application monitoring magnetic field anomalies possibly associated with earthquake precursor activity. Web WW enabled the visualization of the directional vectors from this data to point to the source location of the earthquake. We also developed a prototype urban management application which utilizes OpenStreetMaps to provide simple features such as route navigation, geographical and services information in an area of interest. …

Design And Fabrication Of Liquid Scintillator Counter, Andrea Calderon Saucedo, John L. Orrell

STAR Program Research Presentations

Pacific Northwest National Laboratory (PNNL) is currently developing an ultra-low background liquid scintillator counter (ULB LSC) in the shallow underground laboratory. At a depth of 35-meters water-equivalent, the underground laboratory has a multi-layered shielding to keep out cosmic-ray induced background. The ULB LSC, which is located in a clean room facility, is a multi-layered design made up of various materials, including plastic scintillator veto panels, borated polyethylene, lead and copper. These layers help lower the contributions of the terrestrial background and intrinsic background, resulting from the impurities present in the materials, to the overall background count rate observed by the …

Fortifying Glass, David Guo

STAR Program Research Presentations

Glass can be very fragile, and many techniques have appeared to try to resolve this problem. One technique that has been developed to fortify glass is the depositing of metal atoms into the glass. The specific term for this technique is called “doping.” By combining different metals at different composition ratios, different levels of glass fortifications can be achieved. A pump-probe is applied to the glass which expands and contracts. By shooting electrons at the glass films, an electron diffraction pattern is achieved which contains data from the contraction and expansion of the glass film. This is where this poster …

Mapping Open Water Bodeis With Optical Remote Sensing, Mary Ellen O'Donnell, Erika Podest

STAR Program Research Presentations

There is interest in mapping open water bodies using remote sensing data. Coverage and persistence of open water is currently a poorly measured variable due to its spatial and temporal variability across landscapes, especially in remote areas. The presence and persistence of open water is one of the primary indicators of conditions suitable for mosquito breeding habitats. Predicting the risk of mosquito caused disease outbreaks is a required step towards their control and eradication. Satellite observations can provide needed data to support agency decisions for deployment of preventative measures and control resources. This study, which will try to map open …

Calculating The Energy Barriers Required To Join Metal-Organic Framework Synthesis Intermediates With Non-Equilibrium Molecular Simulation, Marcus A. Tubbs, David Cantu, Roger Rousseau, Vassiliki-Alexandra Glezakou

STAR Program Research Presentations

Metal organic frameworks (MOFs) are synthetic materials made of a cage-like lattice of metal nodes connected by organic linkers. The pores between the nodes define the characteristics of the material. A MOF, MIL-101, has shown great capacity in the adsorption of carbon dioxide and methane, as well as in hydrogenation catalysis with palladium. While there has been success in synthesizing MIL-101 and other MOFs, the mechanistic details behind their assembly remain unknown. Understanding the synthesis mechanism is necessary to understand the kinetics involved and be able to produce this useful material on an industrial scale. Using MIL-101 as a prototypical …

The Effect Of Drought On Stomatal Conductance In The Biosphere 2 Rainforest, Justin Gay, Joost Van Haren

STAR Program Research Presentations

Drought is a major climate change concern for the Earth’s rainforests; however little is currently known about how these forests and individual plants will respond to water stress. At the individual level, the ability of plants to regulate their stomatal conductance is an important preservation mechanism that helps to cool leaves, regulate water loss, and uptake carbon dioxide. At the ecosystem level, transpiration in rain forests is a major contributor to the feedback loop that returns moisture to the atmosphere for continued rains. Nearly 60% of atmospheric moisture in the Amazon rain forests has been traced back to origins of …

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al₂O₃ nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …

An Interactive User Interface Improves Data Visualization In R, Nathan Sweem

STAR Program Research Presentations

An interactive user interface application was created using the R statistical computing environment and the Shiny package to visualize historical data on the performance of mutual funds and exchange-traded funds (ETFs). Historical data for these funds is scraped from the Yahoo! Finance webpage. The application allows the user to analyze this historical data by category and fund family, which are also scraped from Yahoo! Finance. The application generates interactive plots to compare the performance of selected mutual funds and ETFs given the baseline and center determined by the user. The application has been modified to attentively match the data with …

Evaluation Of Anthropogenic Marine Debris And Sargassum Fluitans And Its Potential Impact On Sea Turtle Hatchlings At Sandy Point National Wildlife Refuge, Christina Macmillan

STAR Program Research Presentations

Anthropogenic debris, particularly plastic, has become a significant threat for marine species with the increased use of plastics over the years. Marine birds and sea turtles, mostly green, loggerhead and leatherback turtles, are especially vulnerable to mistaking plastic debris for food and ingesting it. There has been a rise in the incidence of turtles having plastic fragments in their GI tracts; even small amounts of plastic may have major long-term health and reproductive effects. On the nesting beaches, both adults and hatchlings may become entangled in debris or have trouble navigating around beach debris during their crawl to the sea. …

Biochemical, Physiological, And Anatomical Insights Into Aphid-Bioenergy Switchgrass Interactions, Travis J. Prochaska

Department of Entomology: Dissertations, Theses, and Student Research

Switchgrass, Panicum virgatum L., a perennial, warm-season grass native to North America, is a candidate for development as a bioenergy crop. Previously, warm-season grasses were considered to be relatively pest free in their native habitats. However, recent studies using the hemipteran family Aphididae have shown phloem-feeding insects can lead to significant injury in switchgrass. The objectives of this research were to: 1) gain physiological, biochemical, and anatomical insights into insect-bioenergy switchgrass interactions to determine potential insect resistance mechanisms among susceptible and resistant switchgrass genotypes; and 2) to generate and evaluate diverse segregating populations of switchgrass, both resistant and susceptible, to …

Chemistry Of The Protolunar Disk And Volatile Depletion Of The Moon, Channon Visscher, Robin M. Canup, Julien Salmon, Bruce Fegley Jr.

Faculty Work Comprehensive List

In the giant impact theory for lunar origin, the Moon forms from a circumterrestrial disk of silicate debris produced by the collision of a planetary-sized impactor with the early Earth. Recent accretion models suggest that the final 10-60% of the lunar mass may be provided by the accretion of melt material spreading outward from the inner (Roche-interior) disk over the first ~102 years following the giant impact. The chemical and thermal evolution of the inner disk material is thus expected to strongly influence the bulk chemical composition of the Moon.

In a previous study we explored the chemistry of the …

Regional Ocean-Colour Chlorophyll Algorithms For The Red Sea, Robert J.W. Brewin, Dionysios E. Raitsos, Giorgio Dall'olmo, Nikolaos Zarokanellos, Thomas Jackson, Marie Fanny Racault, Emmanuel S. Boss, Shubha Sathyendranath, Burt H. Jones, Ibrahim Hoteit

Marine Sciences Faculty Scholarship

The Red Sea is a semi-enclosed tropical marine ecosystem that stretches from the Gulf of Suez and Gulf of Aqaba in the north, to the Gulf of Aden in the south. Despite its ecological and economic importance, its biological environment is relatively unexplored. Satellite ocean-colour estimates of chlorophyll concentration (an index of phytoplankton biomass) offer an observational platform to monitor the health of the Red Sea. However, little is known about the optical properties of the region. In this paper, we investigate the optical properties of the Red Sea in the context of satellite ocean-colour estimates of chlorophyll concentration. Making …

An Analysis Of Spatio-Temporal Landscape Patterns For Protected Areas In Northern New England: 1099-2010, Spencer Meyer, Mary-Kate Beard-Tisdale, Christopher S. Cronan, Robert Lilieholm

Publications

Context: Landscape ecology theory provides insight about how large assemblages of protected areas (PAs) should be configured to protect biodiversity. We adapted these theories to evaluate whether the emergence of decentralized land protection in a largely private landscape followed the principles of reserve design. Objectives: Our objectives were to determine: (1) Are there distinct clusters of PAs in time and space? (2) Are PAs becoming more spatially clustered through time? and (3) Does the resulting PA portfolio have traits characteristic of ideal reserve design? Methods: We developed an historical dataset of the PAs enacted since 1900 in the northern New …

Stay Awhile And Listen: User Interactions In A Crowdsourced Platform Offering Emotional Support, Derek Doran, Samir P. Yelne, Luisa Massari, Maria-Carla Calzarossa, Latrelle D. Jackson, Glen Moriarty

Computer Science and Engineering Faculty Publications

Internet and online-based social systems are rising as the dominant mode of communication in society. However, the public or semi-private environment under which most online communications operate under do not make them suitable channels for speaking with others about personal or emotional problems. This has led to the emergence of online platforms for emotional support offering free, anonymous, and confidential conversations with live listeners. Yet very little is known about the way these platforms are utilized, and if their features and design foster strong user engagement. This paper explores the utilization and the interaction features of hundreds of thousands of …

Forensic Significance Of Teal Colored Cashmere And Black Acrylic Fibers, Nicole M. Martin

Forensic Science Theses

Textile fibers are a valuable type of trace evidence within forensic cases. They have the ability to connect a perpetrator to a victim and or a crime scene. Some types of fibers are more prevalent than others. The purpose of this research was to conduct a target fiber study in order to determine the significance of the selected fibers in a forensic case. Two fibers were selected from two different garments, black acrylic fiber and a teal colored cashmere fiber. Unknown fibers were collected from three local clothing stores and counted. Using light microscopy, all 20,164 fibers were eliminated as …

Gender And Climate Change In The Indian Himalayas: Global Threats, Local Vulnerabilities, And Livelihood Diversification At The Nanda Devi Biosphere Reserve, Monica V. Ogra, Ruchi Badola

Environmental Studies Faculty Publications

Global climate change has numerous implications for members of mountain communities who feel the impacts in both physical and social dimensions. In the western Himalayas of India, a majority of residents maintain a livelihood strategy that includes a combination of subsistence or small-scale agriculture, livestock rearing, seasonal or long-term migration, and localized natural resource extraction. While warming temperatures, irregular patterns of precipitation and snowmelt, and changing biological systems present challenges to the viability of these traditional livelihood portfolios in general, we find that climate change is also undermining local communities’ livelihood assets in gender-specific ways. In this paper, we present …

Shark Bay Prawn Managed Fishery, M. I. Kangas, E. C. Sporer, S. A. Hesp, K. L. Travaille, S. J. Brand-Gardner, P. Cavalli, A. V. Harry

WA Marine Stewardship Council report series

This report provides a comprehensive description of the Shark Bay Prawn Managed Fishery (SBPMF) and contains information relevant to assist the assessment of this fishery against the Marine Stewardship Council (MSC) standard (v1.3) for sustainable fishing. The SBPMF is located in Shark Bay, Western Australia and uses demersal otter trawl gear to predominantly target brown tiger prawns (Penaeus esculentus) and western king prawns (Penaeus latisulcatus).

Study Of Surface Plasmon Resonance In Metal And Alloy Nanofilms Using Maxwell Description And Metamaterial Simulation In Comsol, Heesoo Park

Graduate Theses - Physics and Optical Engineering

Metamaterials are artificial metallic structures having, possibly, simultaneously negative permittivity and negative permeability which is called a double negative medium. To achieve a visible light range of the metamaterial, the unit cell of the metamaterial units should be 10-200nm. It is a much bigger structure than a size of normal atom. Still, the resolution of fabrication, which is difficult part, should typically be a few nanometers to achieve a nano-level unit. We study Ag thin-film as a convenient candidate for metamaterial over a specific frequency range. Because, the thin film metal is composed of disk shape island structures itself. These …

Effects Of Visualization On Algorithm Comprehension, Matthew Mulvey

Theses and Dissertations

Computer science students are expected to learn and apply a variety of core algorithms which are an essential part of the field. Any one of these algorithms by itself is not necessarily extremely complex, but remembering the large variety of algorithms and the differences between them is challenging. To address this challenge, we present a novel algorithm visualization tool designed to enhance students understanding of Dijkstra’s algorithm by allowing them to discover the rules of the algorithm for themselves. It is hoped that a deeper understanding of the algorithm will help students correctly select, adapt and apply the appropriate algorithm …