Physical Sciences and Mathematics Commons^™

A Study Of The Impacts Of Freeze-Thaw On Cliff Recession At The Calvert Cliffs In Calvert County, Maryland, Bonnie Elizabeth Zwissler

Dissertations, Master's Theses and Master's Reports - Open

The Calvert Cliffs, which form much of the western coastline of the Chesapeake Bay in Calvert County, Maryland, are actively eroding and destabilizing, resulting in a critical situation for many homes in close proximity to the slope's crest. Past studies have identified that where waves directly interact with the toe of the slope, wave action controls cliff recession; however, where waves do not regularly interact with the slope toe, the past work identified that freeze-thaw controls recession. This study investigated the validity of this second claim by analyzing the recession rate and freeze-thaw behavior of six study sites along the …

Evaluation Of Non-Stationarity In Annual Maximum Flood Series Of Moderately Impaired Watersheds In The Upper Midwest And Northeastern United States, Neila Salvadori

Dissertations, Master's Theses and Master's Reports - Open

United States federal agencies assess flood risk using Bulletin 17B procedures which assume annual maximum flood series are stationary. This represents a significant limitation of current flood frequency models as the flood distribution is thereby assumed to be unaffected by trends or periodicity of atmospheric/climatic variables and/or anthropogenic activities. The validity of this assumption is at the core of this thesis, which aims to improve understanding of the forms and potential causes of non-stationarity in flood series for moderately impaired watersheds in the Upper Midwest and Northeastern US. Prior studies investigated non-stationarity in flood series for unimpaired watersheds; however, as …

An Investigation Of Waste Glass-Based Geopolymers Supplemented With Alumina, Mary U. Christiansen

Dissertations, Master's Theses and Master's Reports - Open

An increased consideration of sustainability throughout society has resulted in a surge of research investigating sustainable alternatives to existing construction materials. A new binder system, called a geopolymer, is being investigated to supplement ordinary portland cement (OPC) concrete, which has come under scrutiny because of the CO2 emissions inherent in its production.

Geopolymers are produced from the alkali activation of a powdered aluminosilicate source by an alkaline solution, which results in a dense three-dimensional matrix of tetrahedrally linked aluminosilicates. Geopolymers have shown great potential as a building construction material, offering similar mechanical and durability properties to OPC. Additionally, geopolymers have …

Stilling Basin Scour Remediation Using Air Injection And Flat Plate Extension, Rachael Barlock

Dissertations, Master's Theses and Master's Reports - Open

The South Florida Water Management District (SFWMD) is responsible for managing over 2500 miles of waterways and hundreds of water control structures. Many of these control structures are experiencing erosion, known as scour, of the sediment downstream of the structure. Laboratory experiments were conducted in order to investigate the effectiveness of two-dimensional air diffusers and plate extensions (without air injection) on a 1/30 scale model of one of SFWMD gated spillway structures, the S65E gated spillway. A literature review examining the results of similar studies was conducted. The experimental design for this research was based off of previous work done …

Terpene And Terpenoid Emissions And Secondary Organic Aerosol Production, Rosa M. Flores

Dissertations, Master's Theses and Master's Reports - Open

Approximately 90% of fine aerosol in the Midwestern United States has a regional component with a sizable fraction attributed to secondary production of organic aerosol (SOA). The Ozark Forest is an important source of biogenic SOA precursors like isoprene (> 150 mg m^-2 d^-1), monoterpenes (10-40 mg m^-2 d^-1), and sesquiterpenes (10-40 mg m^-2d^-1). Anthropogenic sources include secondary sulfate and nitrate and biomass burning (51-60%), vehicle emissions (17-26%), and industrial emissions (16-18%). Vehicle emissions are an important source of volatile and vapor-phase, semivolatile aliphatic and aromatic hydrocarbons that are important …