Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
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 give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item IDENTIFYING SMOKE DETECTION BIASES WITHIN DIFFERING ROOM CONFIGURATIONS FOR ZONE AND COMPUTATIONAL FLUID DYNAMIC MODELS(2022) Lee, Adam; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research project aims to identify room configuration conditions in which FDS, a CFD model, and CFAST, a zone model, may differ in detector activation time. A total of four configurations, with varying aspect ratios, were explored. Additionally, a range of four ceiling heights were also modeled. Furthermore, a total of three statistically significant models were developed to relate the differences between detection times within CFAST and FDS. It was found that FDS and CFAST discrepancies were a result of the compartment volume to doorway area ratios. Larger volumes compared to the doorway area resulted in better agreement between FDS and CFAST. Additionally, for larger ceilings in FDS, larger variability in activation times were present. Furthermore, for higher ceilings, FDSs’ ability to account for thermal buoyancy within the smoke plume resulted in quicker activation within FDS.Item Microturbulent transport of non-Maxwellian alpha particles(2015) Wilkie, George John; Dorland, William; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A burning Deuterium-Tritium plasma is one which depends upon fusion-produced alpha particles for self-heating. Whether a plasma can reach a burning state requires knowledge of the transport of alpha particles, and turbulence is one such source of transport. The alpha particle distribution in collisional equilibrium forms a non-Maxwellian tail which spans orders of magnitude in energy, and it is this tail that is responsible for heating the plasma. Newly-born high-energy alpha particles are not expected to respond to turbulence as strongly as alpha particles that have slowed down to the bulk plasma temperature. This dissertation presents a low-collisionality derivation of gyrokinetics relevant for alpha particles and describes the upgrades made to the GS2 flux-tube code to handle general non-Maxwellian energy distributions. With the ability to run self-consistent simulations with a population of alpha particles, we can examine certain assumptions commonly made about alpha particles in the context of microturbulence. It is found that microturbulence can compete with collisional slowing-down, altering the distribution further. One assumption that holds well in electrostatic turbulence is the trace approximation, which is built upon to develop a model for efficiently calculating the coupled radial-energy turbulent transport of a non-Maxwellian species. A new code was written for this purpose and corrections to the global alpha particle heating profile due to microturbulence in an ITER-like scenario are presented along with sensitivity studies.Item Relating Movement and Adjunction in Syntax and Semantics(2010) Hunter, Timothy; Weinberg, Amy; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this thesis I explore the syntactic and semantic properties of movement and adjunction in natural language, and suggest that these two phenomena are related in a novel way. In a precise sense, the basic pieces of grammatical machinery that give rise to movement, also give rise to adjunction. In the system I propose, there is no atomic movement operation and no atomic adjunction operation; the terms "movement" and "adjunction" serve only as convenient labels for certain combinations of other, primitive operations. As a result the system makes non-trivial predictions about how movement and adjunction should interact, since we do not have the freedom to stipulate arbitrary properties of movement while leaving the properties of adjunction unchanged, or vice-versa. I focus first on the distinction between arguments and adjuncts, and propose that the differences between these two kinds of syntactic attachment can be thought of as a transparent reflection of the differing ways in which they contribute to neo-Davidsonian logical forms. The details of this proposal rely crucially on a distinctive treatment of movement, and from it I derive accurate predictions concerning the equivocal status of adjuncts as optionally included in or excluded from a maximal projection, and the possibility of counter-cyclic adjunction. The treatment of movement and adjunction as interrelated phenomena furthermore enables us to introduce a single constraint that subsumes two conditions on extraction, namely adjunct island effects and freezing effects. The novel conceptions of movement and semantic composition that underlie these results raise questions about the system's ability to handle semantic variable-binding. I give an unconventional but descriptively adequate account of basic quantificational phenomena, to demonstrate that this important empirical ground is not given up. More generally, this thesis constitutes a case study in (i) deriving explanations for syntactic patterns from a restrictive, independently motivated theory of compositional semantics, and (ii) using a computationally explicit framework to rigourously investigate the primitives and consequences of our theories. The emerging picture that is suggested is one where some central facts about the syntax and semantics of natural language hang together in a way that they otherwise would not.