10,872 research outputs found

    Method for repair of thin glass coatings

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    A method of repairing cracks or damaged areas in glass, in particular, glass coatings provided on tile. The method includes removing the damaged area using a high speed diamond burr drilling out a cavity that extends slightly into the base material of the tile. All loose material is then cleaned from the drilled out cavity and the cavity is filled adjacent the upper surface of the coating with a filler material including chopped silica fibers mixed with a binder. The filler material is packed into the cavity and a repair coating is applied by means of a brush or sprayed thereover. The repair includes borosilicate suspended in solution. Heat is applied at approximately 2100 F. for approximately five minutes for curing the coating, causing boron silicide particles of the coating to oxidize forming a very fluid boron-oxide rich glass which reacts with the other frits to form an impervious, highly refractory layer

    Study of vortex valve for medium temperature solid propellants

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    Fluid state vortex valve secondary injection control system shows considerable promise for future application to solid propellant rocket engine thrust vector control. The single axis injection system tested would be capable of providing secondary injection thrust vector control using 2000 deg F gas

    Research study of the vortex valve for medium-temperature solid propellants

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    Fluid state control system with vortex valves for solid propellant gas generator flow throttlin

    Spaceborne memory organization, an associative data acquisition system, phase II Final report, Apr. - Dec. 1966

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    Spaceborne memory organization, associative data acquisition system design, and data compression technique

    Microscopic Restoration of Proton-Neutron Mixed Symmetry in Weakly Collective Nuclei

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    Starting from the microscopic low-momentum nucleon-nucleon interaction V{low k}, we present the first systematic shell model study of magnetic moments and magnetic dipole transition strengths of the basic low-energy one-quadrupole phonon excitations in nearly-spherical nuclei. Studying in particular the even-even N=52 isotones from 92Zr to 100Cd, we find the predicted evolution of the predominantly proton-neutron non-symmetric state reveals a restoration of collective proton-neutron mixed-symmetry structure near mid-shell. This provides the first explanation for the existence of pronounced collective mixed-symmetry structures in weakly-collective nuclei.Comment: 5 Pages, 3 figure

    Identifying Potential Breeding Areas of Short-Eared Owls Prior to Nesting Using Roadside Surveys to Detect Courtship and Territoriality Behavior: A Comparison of Visual and Audio Techniques

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    We piloted a roadside survey technique for detecting Short-eared Owls during the courtship period in western Montana.  Thirty-five surveys were conducted between 2009 and 2012 and were timed to coincide with pair-formation and courtship behavior. Short-eared Owls perform courtship flights and vocalizations which can be observed and heard during the crepuscular period.  Surveys were designed to compare visual and audio survey techniques.  Visual surveys occurred during the crepuscular period at the end of civil twilight and were immediately followed by a nocturnal audio survey.  Visual survey techniques accounted for over 91% (N=240) of all detections.  Detections associated with audio survey techniques were almost always associated with survey points where at least one owl was detected during visual survey.  Nearly three-quarters of visual detections (N=220) occurred between 30 and 70 min before the end of civil twilight.  Over 75% of visual detections and 90% of nocturnal detections occurred in areas where vegetation was uncut and ungrazed and most frequently associated with vegetation heights greater than approximately 60cm.  Short-eared Owls were never detected in areas where livestock was present.  We recommend visual surveys during the courtship to identify potential breeding areas prior to the onset of incubation

    Shell model description of the 14C dating beta decay with Brown-Rho-scaled NN interactions

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    We present shell model calculations for the beta-decay of the 14C ground state to the 14N ground state, treating the states of the A=14 multiplet as two 0p holes in an 16O core. We employ low-momentum nucleon-nucleon (NN) interactions derived from the realistic Bonn-B potential and find that the Gamow-Teller matrix element is too large to describe the known lifetime. By using a modified version of this potential that incorporates the effects of Brown-Rho scaling medium modifications, we find that the GT matrix element vanishes for a nuclear density around 85% that of nuclear matter. We find that the splitting between the (J,T)=(1+,0) and (J,T)=(0+,1) states in 14N is improved using the medium-modified Bonn-B potential and that the transition strengths from excited states of 14C to the 14N ground state are compatible with recent experiments.Comment: 4 pages, 5 figures Updated to include referee comments/suggestion

    Rapid, Precise, and High-Sensitivity Acquisition of Paleomagnetic and Rock-Magnetic Data: Development of a Low-Noise Automatic Sample Changing System for Superconducting Rock Magnetometers

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    Among Earth sciences, paleomagnetism is particularly linked to the statistics of large sample sets as a matter of historical development and logistical necessity. Because the geomagnetic field varies over timescales relevant to sedimentary deposition and igneous intrusion, while the fidelity of recorded magnetization is modulated by original properties of rock units and by alteration histories, "ideal" paleomagnetic results measure remanent magnetizations of hundreds of samples at dozens of progressive demagnetization levels, accompanied by tests of magnetic composition on representative sister specimens. We present an inexpensive, open source system for automating paleomagnetic and rock magnetic measurements. Using vacuum pick-and-place technology and a quartz-glass sample holder, the system can in one hour measure remanent magnetizations, as weak as a few pAm2, of ~30 specimens in two vertical orientations with measurement errors comparable to those of the best manual systems. The system reduces the number of manual manipulations required per specimen ~8 fold

    Magnetic forming studies

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    Investigation of the tensile strength dependability on the characteristic time over which a pressure pulse is applied to a metal workpiece shows that the mechanical properties of these materials are functions of the rate at which the material is undergoing strain. These results and techniques are used in magnetomotive metal forming
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