1,131 research outputs found

    Feasibility of JP-8 to Jet a Fuel Conversion at U. S. Military Facilities

    Get PDF
    In FY06, The Department of Defense (DoD) military grade jet fuel expenditures eclipsed $6.6 billion dollars. In a search for more cost effective options, the Office of the Secretary of Defense Comptroller recently expressed interest in the quantity of commercial Jet A fuel that the United States Transportation Command uses in lieu of military grade JP-8. In accordance with AFSO 21 and LEAN concepts, this research examines the technical feasibility and opportunity for cost avoidance of a conversion from JP-8 to Jet A at six Northwestern United States military installations. The technical feasibility analysis examines the chemical likeness of JP-8 and Jet A and identifies any aircraft or equipment that may impede a complete conversion. Accordingly, the opportunity for cost avoidance is considered through an analysis of military and commercial grade jet fuel influenced by West Coast refinery prices. The results show no technical barriers to a complete conversion, but there is no opportunity for cost avoidance

    Friction Pull Plug Welding in Aluminum Alloys

    Get PDF
    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis

    Kinetic simulations of X-B and O-X-B mode conversion

    Full text link
    We have performed fully-kinetic simulations of X-B and O-X-B mode conversion in one and two dimensional setups using the PIC code EPOCH. We have recovered the linear dispersion relation for electron Bernstein waves by employing relatively low amplitude incoming waves. The setups presented here can be used to study non-linear regimes of X-B and O-X-B mode conversion.Comment: 4 pages, 3 figure

    Learning from the Experiences of Collegiate Athletes Living through a Season- or Career-Ending Injury

    Get PDF
    An athlete’s identity is often related to the goals of their team and their ability to achieve excellence in sport. A threat to an athlete’s identity is a season- or career-ending injury. Athletes can respond to season- or career-ending injuries in ways detrimental to their psychosocial well-being (Ivarsson, Tranaeus, Johnson, & Stenling 2017). This study built upon existing knowledge by seeking to better understand the lived experiences of Division I collegiate athletes who experienced a season- or career-ending injury. There is a need for ongoing recommendations for helping athletes process their injuries. Researchers used a descriptive phenomenological approach. Researchers interviewed ten college athletes who experienced a season- or career-ending injury. Themes included: (1) physical and emotional stress, (2) resistance to resiliency, (3) importance of relationships with others, and (4) appreciation and cultivation for new possibilities outside of sport. This research provided insight for behavioral health professionals on injury response. This included the need for Posttraumatic Growth responses such as (1) building strong support pre- and post-injury, (2) recognizing healthy coping mechanisms, (3) cultivating new identities for athletes, (4) helping an athlete with identity loss, (5) helping athletes recognize new possibilities post-injury, and (6) helping an athlete maintain an appreciation for life

    Cytological and ultrastructural preservation in Eocene \u3cem\u3eMetasequoia\u3c/em\u3e leaves from the Canadian High Arctic

    Get PDF
    The ultrastructural examination by transmission electron microscopy of 45-million-year-old mummified leaves of Metasequoia extracted from the Upper Coal member of the Buchanan Lake Formation in Napartulik on Axel Heiberg Island revealed the preservation of intact chloroplasts and chloroplast components. Abundant tanniferous cell inclusions may indicate that the 3-mo period of constant daylight during the Arctic summer induced high concentrations of tannins in the leaf tissues, which may have arrested microbial degradation of the litter. Quantified differences in the extent of chloroplast preservation through a vertical section of the lignite suggest that short-term shifts in the depositional environment took place, perhaps influencing the exposure of the leaf tissues to conditions that would either promote or inhibit decomposition

    Radar derived spatial statistics of summer rain. Volume 3: Appendices

    Get PDF
    A collection of selected important memoranda written during the course of the experiment. It contains detailed information on: (1) frequency diversity, (2) radar controller and radar video processor, (3) SPANDAR calibration, and (4) meteorological summaries
    corecore