28,594 research outputs found

    Assessment of the NASA Flight Assurance Review Program

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    The NASA flight assurance review program to develop minimum standard guidelines for flight assurance reviews was assessed. Documents from NASA centers and NASA headquarters to determine current design review practices and procedures were evaluated. Six reviews were identified for the recommended minimum. The practices and procedures used at the different centers to incorporate the most effective ones into the minimum standard review guidelines were analyzed and guidelines for procedures, personnel and responsibilies, review items/data checklist, and feedback and closeout were defined. The six recommended reviews and the minimum standards guidelines developed for flight assurance reviews are presented. Observations and conclusions for further improving the NASA review and quality assurance process are outlined

    Shuttle orbiter Ku-band radar/communications system design evaluation. Ku band bent-pipe channel performance evaluation

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    Because of difficulties with the bit detector of the SPA mode 1 channel 3 input port, a new bit synchronizer was required. The two prime candidate designs are described and analyzed. The selected design is a modification of one which utilizes a phase frequency detector to track the received data clock frequency and a mid-bit transition point sample detector to generate a bit timing error (phase error) signal to control the relative phase between the local clock and the local data stream. The model used to calculate the effects of cable attenuation and rise time degradation is discussed

    Action of lithium in radiation hardened silicon solar cells Quarterly report, 23 Apr. - 15 Jul. 1968

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    Recovery properties of lithium containing p-n silicon solar cells after radiation damag

    Radiation damage in lithium-containing solar cells Final report, 21 Jun. 1966 - 20 Mar. 1968

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    Interaction of lithium with defects induced in silicon solar cells by one MeV electron bombardmen

    Study to determine and improve design for lithium-doped solar cells Quarterly report, 1 Apr. - 30 Jun. 1970

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    Lithium action effects on spontaneous annealing of radiation damage in bulk silicon and silicon solar cell

    Preliminary Centaur Systems Analysis

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    The Centaur is stored in the Orbiter payload bay on the Centaur Integrated Support System (CISS). The CISS not only cradles the Centaur prior to deployment but also provides any signal conditioning required to make the Centaur/Orbiter hardwire interfaces compatible. In addition, the CISS provides other Centaur functions such as controlling all the avionics safety features and providing all the helium supplies for tank pressurizations. Problems associated with a Centaur design concept using a transponder and two switchable antennas are defined. Solutions to these problems are presented

    A comparison of the in vitro and in planta responses of Phytophthora cinnamomi isolates to phosphite

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    Research in plant pathology often relies on testing interactions between a fungicide and a pathogen in vitro and extrapolating from these results what may happen in planta. Likewise, results from glasshouse experiments are used to estimate what will happen if the fungicide is applied in the field. However, it is difficult to obtain conditions in vitro and in the glasshouse which reflect the conditions where the fungicide may eventually be used, in the field. The aim of this paper is to compare results of the effect of phosphite on P. cinnamomi isolates in vitro and in planta

    Quantum signatures of chaos in the dynamics of a trapped ion

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    We show how a nonlinear chaotic system, the parametrically kicked nonlinear oscillator, may be realised in the dynamics of a trapped, laser-cooled ion, interacting with a sequence of standing wave pulses. Unlike the original optical scheme [G.J.Milburn and C.A.Holmes, Phys. Rev A, 44, p4704, (1991)], the trapped ion enables strongly quantum dynamics with minimal dissipation. This should permit an experimental test of one of the quantum signatures of chaos; irregular collapse and revival dynamics of the average vibrational energy.Comment: 9 pages, 9 Postscript figures, Revtex, submitted to Phys. Rev.
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