Theses and Dissertations from UMD
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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
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Item Cycling the City: Locating Cycling in the Continued (Re)Structuring of North American Cities(2014) Rick, Oliver James Collard; Andrews, David L; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bicycling is a growing mobility practice within contemporary U.S. cities that has multiple effects on the formation of the urban as “We are surrounded by cycling” (Horton et al, 2007, p. 1). This project investigates how cycling has shaped the city by analyzing the role that the governance and practice of cycling currently plays in the political, economic, social, spatial, and affective re-formation of the urban. Through the use of a combination of methods, working at various levels of analysis, the aim is to locate the impact of cycling policies and practices on the structural, discursive, and embodied dimensions of contemporary urban (re)structuring. It is an analysis of macro political processes, the formation of cycling communities, and the experiential dimension of riding in the city. Latham & McCormack (2010) state “cities are constantly generating new forms of collective life, novel ways of being together” (p.55). Thus, this project interrogates the various ways in which cycling impacts upon cities, and influences their (re)formation in potentially “historically unprecedented ways” (Wachsmuth et al, 2011, p. 741). Through studying cycling in Boston, Baltimore, and Washington DC this project provides a multi-sited analysis of how cycling is positioned within U.S. cities currently, as well as the complex and diverse processes that inform the contemporary organization of these urban spaces. U.S. cities currently exist within a broad “climate of cuts, austerity and state retrenchment” (Newman, 2013, p. 1) that has defined current patterns of urban governance. I have researched the ways in which cycling has underpinned and simultaneously challenged these broad shifts toward neoliberal governance. Cycling is both drawn into “marketing of urban “culture” and history by entrepreneurial governance” (Cherot and Murray, 2002, p. 432), but also underpins cities as entities that “defy efforts to be classified into types, reduced to essential characteristics, and fixed by boundaries (intellectual or otherwise)” (Prytherch, 2002, p. 772). As such this project investigates this simultaneously overlapping and contradictory impact of cycling on the city, mapping the multiple locations of cycling within the perpetual (re)formation of the urban.Item DEVELOPMENT OF A DYNAMIC TEST FACILITY FOR ENVIRONMENTAL CONTROL SYSTEMS(2006-04-06) Gado, Amr El-Sayed Alaa El-Din; Radermacher, Reinhard; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Passenger cars and light trucks consume 80% of the total oil imported by U.S.A. Mobile air conditioners (MACs) increase vehicle fuel consumption and exhaust gas emissions. They operate most of the time in a transient state. It is currently impossible to test the performance of an air conditioner during transient operation without it being associated with its intended conditioned space, the car cabin. In this research work a new smart test facility is designed, built, and verified. This facility makes it possible to test the MAC independent of the vehicle, but yet under realistic dynamic conditions. The facility depends on simulation software that measures the conditions of the air supplied by the MAC and subsequently adjusts the conditions of the air returning to the MAC depending on the results of a thermal numerical model of the car cabin that takes into consideration sensible and latent loads, as well as passengers' control settings. It was successful in controlling the temperature and relative humidity within ±0.9°C and ±5% of their respective intended values. The test facility is used to investigate the dynamic performance of a typical R134a MAC system. The tests include pull-down, drive cycle, and cyclic on/off tests. The analysis focuses on the latent capacity and moisture removal due to the difficulty in measuring these variables during field tests. The results show that the most energy efficient method to pull-down the air temperature inside a hot-soaked cabin is to start with fresh air as long as the temperature in the cabin exceeds that of the ambient and then switch to recirculated air. The effect of re-evaporation is illustrated by showing the off-cycle latent capacity. Cyclic tests show that the net moisture removal rate has a minimum at around a 2 minute duty cycles. This implies a means of controlling the coil latent heat factor by varying duty cycle. The automotive air conditioning system is numerically modeled and used in cooperation with the cabin model to conduct numerical tests. The numerical simulation results are compared to the experimental results and the error is less than 1.5 K of cabin air temperature.