UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    USING A BURNING RATE EMULATOR (BRE) TO EMULATE CONDENSED FUELS AND STUDY POOL FIRE BEHAVIOR IN 1G
    (2019) Auth, Eric; Sunderland, Peter B; Quintiere, James G; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The Burning Rate Emulator (BRE) is a device constructed to emulate condensed fuels using gaseous fuel mixtures by matching heat of combustion, heat of gasification, smoke point, and surface temperature. The burner’s heat flux gauges are calibrated for local heat flux measurements and the copper top-plate calorimeter is calibrated for measuring net heat flux to the surface, which allows for determination of an effective heat of gasification to compare to condensed fuels. Seven condensed fuels with known properties are burned and emulated using methane, ethylene, and propylene gas diluted with nitrogen. Propane gas is used to study the general pool fire characteristics displayed by gaseous flames on the BRE. Flame anchoring, flammability regions, flame height, and convective heat transfer are analyzed. Based on a radial heat flux distribution, the readings from the heat flux sensors agree with the calorimeter when applied to a flame. Example flame images are shown.
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    Rapid Harvest of Algae for Biofuel Production with the Aggregating Bacterium Bacillus sp. strain RP1137.
    (2014) Powell, Ryan Joseph; Hill, Russell T; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Algal biofuels represent one of the most promising means of sustainably replacing liquid fuels. However significant challenges remain before algal based fuels become competitive with fossil fuels. One of the largest challenges is the ability to harvest the algae in an economic and low energy manner. In this dissertation I describe the isolation of the bacterium, Bacillus sp. strain RP1137, which can rapidly aggregate several algae that are candidates for biofuel production. This bacterium aggregates algae in a pH dependent and reversible manner and retains its aggregation ability after paraformaldehyde fixation. The optimal ratio of bacteria to algae is described as well as the robustness of aggregation at different salinities and temperatures. Aggregation is dependent on the presence of calcium or magnesium ions and likely occurs via charge neutralization through binding of calcium ions to the cell surface of both algae and bacteria. I show charge neutralization occurs at least in part through binding of calcium to negatively charged teichoic acid residues. A comparison of the aggregation efficiency of RP1137, Bacillus megaterium QM B1551 and Bacillus subtilis SMY showed that RP1137 and B1551 are equally efficient at aggregating algae while SMY does not aggregate algae. The genome of RP1137 was sequenced to understand the molecular underpinning of the mechanism of aggregation. The difference in aggregation phenotypes between the three bacilli was used to inform a genomic comparison which revealed two putative proteins that are predicted to be bound to the cell wall and are found only in RP1137 and B1551 but not SMY. This work characterizes the conditions under which Bacillus sp. RP1137 aggregates algae and the mechanism by which that aggregation occurs.
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    Fire Safety of Today's and Tomorrow's Vehicles
    (2008-05-02) Levy, Kevin Martin; Sunderland, Peter B; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis considers fire hazards in the existing vehicle fleet and uses failure modes and effects analyses of three generic designs to identify and rank potential fire hazards in the Emerging Fuel Vehicle (EFV) fleet. A statistics based predictive quantitative risk assessment framework and estimated uncertainty analysis is presented to predict risk of EFV fleets. The analysis also determines that the frequency of fire occurrence is the greatest factor that contributes to risk of death in fire. These preliminary results predict 420±14 fire related deaths per year for a fleet composed entirely of gasoline-electric hybrid vehicles, 910±340 for compressed natural gas vehicles, and 1300±570 for hydrogen fuel-cell vehicles relative to the statistical record of 350 for traditional fuel vehicles. The results are intended to provide vital fire safety information to the traveling public as well as to emergency response personnel to increase safety when responding to EFV fire hazards.