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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2010 - 20112

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    EFFECT OF KINEMATIC VARIATIONS ON VISCOUS PUMPING BY A ROBOTIC GILL PLATE ARRAY
    (2011) Larson, Mary Alexandra; Kiger, Kenneth; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    As the Reynolds number of a system decreases, traditional pumping techniques become less effective. In nature, oscillating appendage systems exhibit distinct patterns of movement based on their Reynolds number. Studies of pumping by mayfly nymph gill arrays have shown different kinematics over Reynolds numbers from 2 to 22. To understand why and how this pumping mechanism might be optimized, a robotic oscillating plate array was constructed allowing stroke and pitch variation as well as phase lag variation between adjacent gills. Stereoscopic PIV was used to obtain three dimensional velocity data, allowing computation of the net pumping rate and flow induced dissipation for five cases, focusing on the role of the gill plate interactions and their dependence on the phase lag. The results indicate that mayfly gills most likely use a phase lag of 90° because it produces the highest net mass flow rate and has the highest specific flux efficiency.
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    Meeting the Needs of the Nontraditional Student:: A Study of the Effectiveness of Synchronous Online Writing Center Tutorials
    (2010) Hawkinson Melkun, Cheryl Lee; Donawerth, Jane; English Language and Literature; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In the fall of 2007, 3.9 million students took at least one online course, reflecting an online education growth rate of 12.9 percent. Many online students are nontraditional, possessing one or more of the following characteristics: delayed enrollment, part time attendance, full-time worker, financially independent as related to financial aid, dependents other than a spouse, single parent, a GED or did not finish high school. While these students bring diversity and life experience to the classroom, they are often ill-prepared for college writing. Though they need help, hectic schedules make it difficult to meet with a writing consultant. This study investigates whether synchronous writing center tutorials can effectively address this client population's needs. Currently, there is a dearth of scholarship relating to online writing tutorials, particularly synchronous tutorials. This two-year study of 189 face-to-face clients and 90 online clients employs quantitative and qualitative research to determine (1) the demographic profile of online users, (2) reasons clients meet online, (3) help sought online, (4) online client preparation, (5) client perceptions of online sessions, and (6) advantages and disadvantages of online sessions. Data were culled from a client questionnaire, online session logs, and consultant and client interviews. Statistically significant differences in client demographics between face-to-face and online users were found in age, ethnicity, and gender: online clients are younger, are more likely to be white, and are more likely to be male. Clients meet online primarily for convenience; however, there is no correlation between distance from campus and online client usage. There were no significant differences in client preparation. Spelling was the only statistically significant category in help sought: online clients seek more spelling help than their face-to-face counterparts. Face-to-face and online clients both viewed their sessions as successful with no statistically significant difference between the groups. Over one-third of clients reported technical problems during their session, and some clients expressed a preference for the emphatic cues found in face-to-face consultations. Advantages of online sessions included assistance with word processing features, the ability to make revisions to the working document, and the ability to record the session.