Physical Sciences and Mathematics Commons^™

Improving The Efficiency Of Organic Solar Cells By Varying The Material Concentration In The Photoactive Layer, Kevin Anthony Latimer

Electrical & Computer Engineering Theses & Dissertations

Polymer-fullerene bulk heterojunction solar cells have been a rapidly improving technology over the past decade. To further improve the relatively low energy conversion efficiencies of these solar cells, several modifications need to be made to the overall device structure. Emerging technologies include cells that are fabricated with interfacial layers to facilitate charge transport, and tandem structures are being introduced to harness the absorption spectrum of polymers with varying bandgap energies.

When new structures are implemented, each layer of the cell must be optimized in order for the entire device to function efficiently. The most volatile layer of these devices is …

Controls On The Formation Of Algal Blooms In The Lower Chesapeake Bay And Its Tributaries, Ryan Eric Morse

OES Theses and Dissertations

Algal blooms occur seasonally in the Chesapeake Bay and its tributaries, and while the consequences of algal blooms have been qualitatively and quantitatively assessed, the causes of algal blooms and mechanisms of bloom initiation are still not well understood despite decades of research. In order to understand nutrient dynamics and other factors that promote the initiation of algal blooms, the Lafayette River, a tidal sub-estuary of Chesapeake Bay that experiences seasonal algal blooms, was sampled daily in the fall of 2005. Three phytoplankton blooms (Chlorophyll a concentrations exceeding twice the average of monthly measurements from 2000-2009) occurred during this period, …

The Effect Of An Offshore Wind Turbine Array On Circulation In An Idealized Coastal Ocean, Mahmoud Kamel

OES Theses and Dissertations

The effect of arrays of wind turbines on circulation in the coastal ocean is analyzed with a coastal numerical model applied to a shallow coastal area like the Mid Atlantic Bight (MAB). A simplified model domain is specified with a linearly deepening shelf along a straight coastline. The initial density structure is a quasi-two layer situation with a sharp thermocline. Wind stress in most of the cases is either upwelling or downwelling favorable with constant amplitude continuing after a smooth start. There are two cases where oscillating wind forcing is used. Simulations consider wind arrays having different widths, different locations …

Effects Of 11 Years Of Co2 Enrichment On Root Biomass And Spatial Distribution In A Florida Scrub-Oak Ecosystem, Rachel Eilenfield Schroeder

Biological Sciences Theses & Dissertations

A Florida (USA) scrub-oak ecosystem was exposed to elevated atmospheric CO₂ in open-top chambers from 1996-2007. Minirhizotrons and ground-penetrating radar (GPR) were used to measure fine root (< 2 mm diameter) and coarse root (> 5 mm diameter) biomass, respectively. After 11 years of CO₂ enrichment, there was a trend of greater total root biomass under elevated CO₂. Fine root biomass exhibited a pattern of recovery and steady state throughout the study, with significant CO₂ stimulation observed only after disturbance. Greater root biomass under elevated CO₂ during recovery periods could result in greater carbon inputs belowground, alteration of the soil carbon …

Spatially-Explicit Agent-Based Modeling Of Ecosystem Change And Epizootiological Impacts On Caribbean Spiny Lobster, Panulirus Argus, Thomas William Dolan Iii

Biological Sciences Theses & Dissertations

Agent-based models explicitly incorporate interactions and variation at the individual level, just as in the real world. As a result, agent-based models are realistic, intuitive, and generally less complex mathematically than their analytical counterparts. Their primary disadvantage is the large amount of detailed data required to construct and parameterize them. Although the use of agent-based simulation is increasing in ecology, they are highly specific, so are rarely used for development of theory. To demonstrate the flexibility and utility of this approach I developed a multi-species, agent-based, spatially-explicit model of the spiny lobster nursery of southern Florida that incorporates changing salinities, …

Elementary Teachers' Views Of Environmental Education, Rose M. Hotchkiss

Teaching & Learning Theses & Dissertations

The purpose of this research is to examine teachers' views of environmental education (EE) at the elementary level. The study addresses teachers' attitudes toward the EE at the elementary school level and their self-efficacy in teaching EE.

The study's sample consisted of 201 randomly selected kindergarten through fifth grade United States public school teachers. The participants completed an on-line survey with eight percent of the respondents participating in follow up interviews. The questionnaire measured two constructs; Teachers Attitudes Toward EE and Teacher Efficacy in EE. Teachers Attitudes Toward EE had 3 subscales; Advocacy for EE, Stewardship in EE, …

Hybrid Inorganic/Organic Nanostructured Tandem Solar Cells: Simulation And Fabrication Methods, Patrick Michael Boland Jr.

Electrical & Computer Engineering Theses & Dissertations

Organic solar cell technologies continue to be an extremely active area of scientific research. With their promise of providing low-cost, easily-processable, multi-application photovoltaics, these devices could very possibly be the most viable and practical form of renewable energy among many being explored. However, significant technological obstacles remain that must be overcome if this technology is to successfully realize the goal of providing abundant energy while simultaneously reducing dependence on fossil fuel-based sources. Compared with inorganic solar photovoltaics, power conversion efficiencies in organics are still too low to compete economically.

Much research has been accomplished over the past three decades in …