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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Author: search.filters.author.Hall, Sarah Elizabeth

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    Factors Affecting University GPA of Maryland Community College Transfer Students Who Persist to Graduation
    (2005-05-27) Hall, Sarah Elizabeth; Clement, Linda; Counseling and Personnel Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This study examined Maryland community college transfer students who persist to graduation. Personal characteristics, academic qualifications, and major were examined to determine if any of these factors were predictors of university GPA. These characteristics were: age, race, gender, community college, transfer GPA, first semester GPA, accepted transfer credits, completion of freshmen fundamental studies, Associates degree completion, and college of major. The sample consisted of 530 subjects. The data analysis revealed significant results. Age, race, gender, transfer GPA, first semester GPA, and college of major were all significant predictors of variance in cumulative GPA for community college transfer students. Women, White subjects, and College of Education graduates were significantly more likely to earn higher cumulative GPAs than other subjects within each of these variables. University GPA was significantly correlated with age, transfer GPA, and first semester GPA. These findings have practical implications for admissions and student support services at four-year institutions.
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    Model Following Control Strategies and Human Interface Techniques for the Treatment of Time Delay During Teleoperation
    (2004-11-24) Hall, Sarah Elizabeth; Sanner, Robert M; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Teleoperation of remotely located space/underwater vehicles requires the human operator to interact with time delayed vehicle responses to issued commands. This often results in the adoption of a ``move and wait'' strategy whereby the vehicle operator waits to view the results of the previous command before issuing the next command. This work investigates combining a command display (CD) located at the operator control station with a model following controller residing on the remote vehicle to allow the teleoperator to interact with the vehicle in a more seamless manner in time delayed environments. Command displays differ from more traditional predictive displays in two major ways. First, in a CD system, a trajectory tracking controller is located on the remote vehicle; the teleoperator interacts with an ideal kinematic model of the vehicle at the control station, with the controller forcing the vehicle to fly the indicated trajectory. Second, model information resides on board the vehicle controller in a CD. In a predictor display system the prediction model is located at the control station. The utility of implementing a CD on a full 6 DOF dynamic simulation of an underwater remotely operated vehicle (UROV) is examined. The task involves 18 subjects maneuvering the UROV through an obstacle course. Sensitivity of the CD to model accuracy is addressed, i.e. does implementation of a vehicle controller capable of adaptation in the presence of model uncertainty improve performance. Successful implementation of an adaptive CD is demonstrated. Results indicate that the CD is instrumental in improving performance for teleoperated systems with signal transmission delays as seen by decreased completion times, improved accuracy and more consistent use of hand controllers. In addition, the CD proves surprisingly robust to model inaccuracy when time delay is present. On the other hand, results indicate that implementation of a CD may be contraindicated in the absence of time delay. There is evidence that discrepancies between the actual and desired vehicle due to controller accuracy may have confused the test subjects. Task completion times are higher and subjects are less accurate when the CD is implemented with no time delay.