15,393 research outputs found

    MS-171: Corporal Luther Jacob ā€œJakeā€ Thomas Papers

    Full text link
    This collection consists of letters, photographs, documents, and artifacts relating to Luther J. ā€œJakeā€ Thomasā€™s military service during the Second World War. The majority of the collection features correspondence between Thomas and his family, particularly his mother Anna Thomas, between 1943 and 1945. While serving as an MP in the Army Air Corps, Thomas regularly mailed letters and photographs home detailing his training, travels, and experiences as a soldier. The collection also includes Thomasā€™s military documentation (for example, induction and separation papers), training materials, wartime souvenirs and artefacts, and post-war awards and honors. The collection includes documents related to Thomasā€™s veteran status following his discharge in late 1945, as well as his subsequent enrollment in the Philadelphia College of Pharmacy. Finally, the collection contains general information about the Thomas family, including photographs, obituaries, and documents concerning Luther C. Thomas (Thomasā€™s father)ā€™s military service in World War I. Special Collections and College Archives Finding Aids are discovery tools used to describe and provide access to our holdings. Finding aids include historical and biographical information about each collection in addition to inventories of their content. More information about our collections can be found on our website http://www.gettysburg.edu/special_collections/collections/.https://cupola.gettysburg.edu/findingaidsall/1142/thumbnail.jp

    Shallow grooves in journal improve air bearing performance

    Get PDF
    Bearing designs, which shape the surface to create artificial fluid-film wedges in the absence of any applied radial load, generate radial restoring forces to keep journals from whirling. Helical- or herringbone-grooved journals or rotors show most promise of stable operation, with no sacrifice in load capacity

    Case studies to enhance online student evaluation: Bond University ā€“ Surveying students online to improve learning and teaching

    Get PDF
    One of the most sensible ways of improving learning and teaching is to ask the students for feedback. At the end of each teaching period (i.e. semester or term) all universities and many schools survey their students. Usually these surveys are managed online. Questions ask for student perceptions about teaching, assessment and workload. The survey administrators report four common problems

    Experimental dynamic stiffness and damping of externally pressurized gas-lubricated journal bearings

    Get PDF
    A rigid vertical shaft was operated with known amounts of unbalance at speeds to 30,000 rpm and gas supply pressure ratios to 4.8. From measured amplitude and phase angle data, dynamic stiffness and damping coefficients of the bearings were determined. The measured stiffness was proportional to the supply pressure, while damping was little affected by supply pressure. Damping dropped rapidly as the fractional frequency whirl threshold was approached. A small-eccentricity analysis overpredicted the stiffness by 20 to 70 percent. Predicted damping was lower than measured at low speeds but higher at high speeds

    Experiments on rotating externally pressurized air journal bearings. Part 2 - Attitude angle and air flow

    Get PDF
    Air flow and attitude angle compared with theory for rotating externally pressurized air journal bearing

    Empirical wind model for the middle and lower atmosphere. Part 1: Local time average

    Get PDF
    The HWM90 thermospheric wind model was revised in the lower thermosphere and extended into the mesosphere and lower atmosphere to provide a single analytic model for calculating zonal and meridional wind profiles representative of the climatological average for various geophysical conditions. Gradient winds from CIRA-86 plus rocket soundings, incoherent scatter radar, MF radar, and meteor radar provide the data base and are supplemented by previous data driven model summaries. Low-order spherical harmonics and Fourier series are used to describe the major variations throughout the atmosphere including latitude, annual, semiannual, and longitude (stationary wave 1). The model represents a smoothed compromise between the data sources. Although agreement between various data sources is generally good, some systematic differences are noted, particularly near the mesopause. Root mean square differences between data and model are on the order of 15 m/s in the mesosphere and 10 m/s in the stratosphere for zonal wind, and 10 m/s and 4 m/s, respectively, for meridional wind

    James J. Kaput (1942ā€“2005) imagineer and futurologist of mathematics education

    Get PDF
    Jim Kaput lived a full life in mathematics education and we have many reasons to be grateful to him, not only for his vision of the use of technology in mathematics, but also for his fundamental humanity. This paper considers the origins of his ā€˜big ideasā€™ as he lived through the most amazing innovations in technology that have changed our lives more in a generation than in many centuries before. His vision continues as is exemplified by the collected papers in this tribute to his life and work

    PARAMETER DEPENDENCE OF ACOUSTOELECTRIC AMPLIFICATION IN InSb

    Full text link
    On the basis of a hydrodynamical theory of the acoustoelectric interaction (Fleming-Rowe) reported earlier which included electron inertial terms it is found that for sufficiently large electron drift velocities sharp high-gain peaks occur. Furthermore the peak values of gain achieved greatly exceed the maximum gain of the corresponding theory of Steele. Excellent agreement with recently reported experimental measurements of microwave acoustic gain in InSb is obtained. It is also noted that for large applied fields, empirical field factors are required to give agreement with experiment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70684/2/APPLAB-18-3-96-1.pd
    • ā€¦
    corecore