33,638 research outputs found

    Tool for installing or extracting small bulbs in limited-access spaces

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    Installing and extracting component of tool is plastic tubing with inside diameter which provides snug fit over bulb. Other components, which provide sturdiness and ease of operation, consist of metal tube, with collar near one end, and plunger, with knob on one end and Teflon tip on the other

    Weather data dissemination to aircraft

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    Documentation exists that shows weather to be responsible for approximately 40 percent of all general aviation accidents with fatalities. Weather data products available on the ground are becoming more sophisticated and greater in number. Although many of these data are critical to aircraft safety, they currently must be transmitted verbally to the aircraft. This process is labor intensive and provides a low rate of information transfer. Consequently, the pilot is often forced to make life-critical decisions based on incomplete and outdated information. Automated transmission of weather data from the ground to the aircraft can provide the aircrew with accurate data in near-real time. The current National Airspace System Plan calls for such an uplink capability to be provided by the Mode S Beacon System data link. Although this system has a very advanced data link capability, it will not be capable of providing adequate weather data to all airspace users in its planned configuration. This paper delineates some of the important weather data uplink system requirements, and describes a system which is capable of meeting these requirements. The proposed system utilizes a run-length coding technique for image data compression and a hybrid phase and amplitude modulation technique for the transmission of both voice and weather data on existing aeronautical Very High Frequency (VHF) voice communication channels

    Fracture toughness of SiC/Al metal matrix composite

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    An experimental study was conducted to evaluate fracture toughness of SiC/Al metal matrix composite (MMC). The material was a 12.7 mm thick extrusion of 6061-T6 aluminum alloy with 40 v/o SiC particulates. Specimen configuration and test procedure conformed to ASTM E399 Standard for compact specimens. It was found that special procedures were necessary to obtain fatigue cracks of controlled lengths in the preparation of precracked specimens for the MMC material. Fatigue loading with both minimum and maximum loads in compression was used to start the precrack. The initial precracking would stop by self-arrest. Afterwards, the precrack could be safely extended to the desired length by additional cyclic tensile loading. Test results met practically all the E399 criteria for the calculation of plane strain fracture toughness of the material. A valid K sub IC value of the SiC/Al composite was established as K sub IC = 8.9 MPa square root of m. The threshold stress intensity under which crack would cease to grow in the material was estimated as delta K sub th = 2MPa square root of m for R = 0.09 using the fatigue precracking data. Fractographic examinations show that failure occurred by the micromechanism involved with plastic deformation although the specimens broke by brittle fracture. The effect of precracking by cyclic loading in compression on fracture toughness is included in the discussion

    Relation Between Einstein And Quantum Field Equations

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    We show that there exists a choice of scalar field modes, such that the evolution of the quantum field in the zero-mass and large-mass limits is consistent with the Einstein equations for the background geometry. This choice of modes is also consistent with zero production of these particles and thus corresponds to a preferred vacuum state preserved by the evolution. In the zero-mass limit, we find that the quantum field equation implies the Einstein equation for the scale factor of a radiation-dominated universe; in the large-mass case, it implies the corresponding Einstein equation for a matter-dominated universe. Conversely, if the classical radiation-dominated or matter-dominated Einstein equations hold, there is no production of scalar particles in the zero and large mass limits, respectively. The suppression of particle production in the large mass limit is over and above the expected suppression at large mass. Our results hold for a certain class of conformally ultrastatic background geometries and therefore generalize previous results by one of us for spatially flat Robertson-Walker background geometries. In these geometries, we find that the temporal part of the graviton equations reduces to the temporal equation for a massless minimally coupled scalar field, and therefore the results for massless particle production hold also for gravitons. Within the class of modes we study, we also find that the requirement of zero production of massless scalar particles is not consistent with a non-zero cosmological constant. Possible implications are discussed.Comment: Latex, 24 pages. Minor changes in text from original versio

    Procedures for management control of computer programming in Apollo

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    Procedures for management control of computer programming in Apollo projec

    Populations of Pear Thrips, \u3ci\u3eTaeniothrips Inconsequens\u3c/i\u3e (Thysanoptera: Thripidae) in Sugar Maple Stands in Vermont: 1989-2005

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    Development of an effective IPM strategy for pear thrips, Taeniothrips inconsequens (Uzel) (Thysanoptera: Thripidae), a pest of sugar maple, Acer saccharum Marshall, demands an understanding of their population fluctuations over time. Pear thrips populations were monitored using a standardized soil sampling method every fall from 1989 – 2005 in 14 counties of Vermont (U.S.). Data from individual sites were combined into north, central and south regions. High numbers of thrips emerged from soil sampled in 1989, 1990, 1993 and 2001, particularly in the north region (Washington, Lamoille, and Franklin counties). The central and south regions had lower pear thrips populations over all years. These results provide, for the first time, fundamental knowledge of pear thrips populations across a wide geographical area of Vermont and will assist in the design of suitable control strategies for pear thrips in the future

    The scientific evaluation of music content analysis systems: Valid empirical foundations for future real-world impact

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    We discuss the problem of music content analysis within the formal framework of experimental design

    Spatial curvature effects on molecular transport by diffusion

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    For a substance diffusing on a curved surface, we obtain an explicit relation valid for very small values of the time, between the local concentration, the diffusion coefficient, the intrinsic spatial curvature and the time. We recover the known solution of Fick's law of diffusion in the flat space limit. In the biological context, this result would be useful in understanding the variations in the diffusion rates of integral proteins and other molecules on membranes.Comment: 10 page

    New World of Gossamer Superconductivity

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    Since the discovery of the high-Tc_{c} cuprate superconductor La2−x_{2-x}BaCuO4_{4} in 1986 by Bednorz and M\"{u}ller, controversy regarding the nature or origin of this remarkable superconductivity has continued. However, d-wave superconductivity in the hole-doped cuprates, arising due to the anti-paramagnon exchange, was established around 1994. More recently we have shown that the mean field theory, like the BCS theory of superconductivity and Landau's Fermi liquid theory are adequate to describe the cuprates. The keys for this development are the facts that a)the pseudogap phase is d-wave density wave (dDW) and that the high-Tc_{c} cuprate superconductivity is gossamer (i.e. it exists in the presence of dDW).Comment: 6 pages, 4 figure
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