26,452 research outputs found

    Lasers incorporating two-dimensional photonic crystal mirrors

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    Photonic bandgap crystals are expected to be of use in defining microcavities for modifying spontaneous emission and as highly reflective mirrors. There are several reports of microfabricating one-dimensional structure. Here, we describe the incorporation of a microfabricated two-dimensional photonic lattice in an edge-emitting semiconductor laser structure. We demonstrate laser operation in a cavity formed between a cleaved facet and a microfabricated periodic lattice

    The Effect of Mentoring on the Academic Success of College Sophomores

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    A review of the higher education literature indicates that the majority of retention research has focused on first-year students and that additional research is needed for other class levels – particularly sophomores (Graunke & Woosley, 2005). However, the reality is that sophomores benefit from a minimal number of special programs, minimal contact with faculty and others in leadership positions, and minimal attention from student affairs personnel (Anderson & Schreiner, 2000). An unintended consequence of this reduced attention is higher than expected rates of sophomore attrition. This exploratory research study employs a quasi-experimental quantitative research design to evaluate the results of a mentoring program for sophomore students. The instruments utilized to support the study are the Student Role Commitment Scale and the Academic Skills Comfort Scale from the Transition to College Inventory (TCI). Academic success was assessed using cumulative GPA and retention of students from sophomore to junior status. The findings of the study are analyzed and presented, and areas for future research are highlighted. The findings indicate that mentoring can have a significant impact on sophomore student academic success, which can lead to higher grades and persistence. Finally, the study suggested directions for continued research and actions that might taken to increase student academic success in higher education settings

    Weighted feature selection criteria for visual servoing of a telerobot

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    Because of the continually changing environment of a space station, visual feedback is a vital element of a telerobotic system. A real time visual servoing system would allow a telerobot to track and manipulate randomly moving objects. Methodologies for the automatic selection of image features to be used to visually control the relative position between an eye-in-hand telerobot and a known object are devised. A weighted criteria function with both image recognition and control components is used to select the combination of image features which provides the best control. Simulation and experimental results of a PUMA robot arm visually tracking a randomly moving carburetor gasket with a visual update time of 70 milliseconds are discussed

    GOES-next navigation operations

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    The next generation of Geostationary Operational Environmental Satellites, GOES-I through -M (hereafter referred to as GOES-Next), begins a new era in the operation of weather satellites by the National Oceanic and Atmospheric Administration (NOAA). With a new spacecraft design, three-axis attitude stabilization, new ground support equipment, and improved methods of image navigation and registration that use on board compensation techniques to correct images for satellite motion, NOAA expects improved performance over the current series of dual-spin spacecraft. To meet these expectations, planning is currently underway for providing the complex and intensive operational environment that will meet the challenge of operating the GOES-Next spacecraft. This paper describes that operational environment
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