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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2005 - 20102

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    A Tannakian Description for Parahoric Bruhat-Tits Group Schemes
    (2010) Wilson, Kevin Michael; Haines, Thomas; Mathematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Let K be a field which is complete with respect to a discrete valuation and let O be the ring of integers in K. We study the Bruhat-Tits building B(G) and the parahoric Bruhat-Tits group schemes GF associated to a connected reductive split linear algebraic group G defined over O. In order to study these objects we use the theory of Tannakian duality, developed by Saavedra Rivano, which shows how to recover G from its category of finite rank projective representations over O. We also use Moy-Prasad filtrations in order to define lattice chains in any such representation. Using these two tools, we give a Tannakian description to B(G). We also define a functor AutF associated to a facet F in B(G) in terms of lattice chains in a Tannakian way. We show that AutF is representable by an affine group scheme of finite type, has the same generic fiber as G, and satisfies AutF(OE) = GF (OE) for every unramified Galois extension E of K. Moreover, we show that there is a canonical morphism from GF to AutF, which we conjecture to be an isomorphism. We prove that it is an isomorphism when the residue characteristic of K is zero and G is arbitrary, when G = GLn and K is arbitrary, and when F is the minimal facet containing the origin and G and K are arbitrary.
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    Experimental and Theoretical Investigation of Integrated Engine Generator - Liquid Desiccant System
    (2005-11-30) Nayak, Sandeep M; Radermacher, Reinhard; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Combined heat and power (CHP) involves on-site generation of electricity by using gas-fired equipment along with utilization of waste heat available from the power generation process. This research focuses on the design, installation and analysis of integration options of a modular CHP system involving the integration of a natural gas fired reciprocating engine generator with a liquid desiccant dehumidification system in a medium sized commercial office building. The engine generator provides 75 kW of electrical power fed parallel to the grid while the combined waste heat from the exhaust gases and jacket water from the engine is used to regenerate the liquid desiccant. The liquid desiccant unit dehumidifies the outdoor air and supplies it to the mixed air section of the roof top unit of the building. The experimental part of the research discusses the various aspects involved in the design and installation of the system such as the mechanical design of the structure, the heat recovery loop design and the electrical interconnection with the grid. Extensive testing and data analysis was conducted to characterize the performance of the integrated system and compare the performance with a traditional power plant as well as conventional HVAC systems. A comprehensive steady state thermodynamic model of the integrated CHP system was coded in Visual Basic .Net. After validation with experimental results, an economic and climate model was integrated into the thermodynamic model with actual electricity and gas prices as well as the climate data for different representative states in the United States to demonstrate the feasibility of the system under different scenarios. This research addresses and assesses the different integration opportunities and issues encountered during the integration of the engine generator - liquid desiccant system with the existing electrical grid and the roof top unit. Based on the hands-on experience gained during the design, installation, operation and maintenance of the integrated system as well as the results obtained from extensive simulation of the system, this research develops valuable design guidelines on the integration and operation of the packaged engine generator-liquid desiccant system in commercial office buildings for future designers and system integrators.