36,742 research outputs found

    Turbine vane coolant flow variations and calculated effects on metal temperatures

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    Seventy-two air-cooled turbine vanes were tested to determine coolant flow variations among the vanes. Calculations were made to estimate the effect of measured coolant flow variations on local vane metal temperatures. The calculations were based on the following assumed operating conditions: turbine inlet temperature, 1700 K (2600 F); turbine inlet pressure, 31 N/sq cm (45 psia); coolant inlet temperature, 811 K (1000 F); and total coolant to gas flow ratio, 0.065. Variations of total coolant flow were not large (about 10 percent from the arithmetic mean) for all 72 vanes, but variations in local coolant flows were large. The local coolant flow variations ranged from 8 to 75 percent, and calculated metal temperature variations ranged from 8 to 60 K (15 to 180 F)

    Three-dimensional modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn

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    While lightning activity in Venus is still controversial, its existence in Jupiter and Saturn was first detected by the Voyager missions and later on confirmed by Cassini and New Horizons optical recordings in the case of Jupiter, and recently by Cassini on Saturn in 2009. Based on a recently developed 3D model we investigate the influence of lightning-emitted electromagnetic pulses (EMP) on the upper atmosphere of Venus, Saturn and Jupiter. We explore how different lightning properties such as total energy released and orientation (vertical, horizontal, oblique) can produce mesospheric transient optical emissions of different shapes, sizes and intensities. Moreover, we show that the relatively strong background magnetic field of Saturn can enhance the lightning-induced quasi-electrostatic and inductive electric field components above 1000 km of altitude producing stronger transient optical emissions that could be detected from orbital probes

    An excess of damped Lyman alpha galaxies near QSOs

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    We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within 6000 km/s of the QSO's systemic redshift (z_sys). Our sample is based on 731 2.5 < z_sys < 4.5 non-broad-absorption-line (non-BAL) QSOs from Data Release 3 (DR3) of the SDSS. We estimate that our search is ~100 % complete for absorbers with N(HI) >= 2e20 cm^-2. The derived number density of DLAs per unit redshift, n(z), within v < 6000 km/s is higher (3.5 sigma significance) by almost a factor of 2 than that of intervening absorbers observed in the SDSS DR3, i.e. there is evidence for an overdensity of galaxies near the QSOs. This provides a physical motivation for excluding DLAs at small velocity separations in surveys of intervening 'field' DLAs. In addition, we find that the overdensity of proximate DLAs is independent of the radio-loudness of the QSO, consistent with the environments of radio-loud and radio-quiet QSOs being similar.Comment: Accepted for publication in MNRAS (13 pages, 6 figures

    Fiber optic control system integration

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    A total fiber optic, integrated propulsion/flight control system concept for advanced fighter aircraft is presented. Fiber optic technology pertaining to this system is identified and evaluated for application readiness. A fiber optic sensor vendor survey was completed, and the results are reported. The advantages of centralized/direct architecture are reviewed, and the concept of the protocol branch is explained. Preliminary protocol branch selections are made based on the F-18/F404 application. Concepts for new optical tools are described. Development plans for the optical technology and the described system are included

    Acrylamide Production Using Encapsulated Nitrile Hydratase from \u3cem\u3ePseudonocardia thermophila\u3c/em\u3e in a Sol–gel Matrix

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    The cobalt-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase) was successfully encapsulated in tetramethyl orthosilicate sol–gel matrices to produce a PtNHase:sol–gel biomaterial. The PtNHase:sol–gel biomaterial catalyzed the conversion of 600 mM acrylonitrile to acrylamide in 60 min at 35 °C with a yields of \u3e90%. Treatment of the biomaterial with proteases confirmed that the catalytic activity is due to the encapsulated enzyme and not surface bound NHase. The biomaterial retained 50% of its activity after being used for a total of 13 consecutive reactions for the conversion of acrylonitrile to acrylamide. The thermostability and long-term storage of the PtNHase:sol–gel are substantially improved compared to the soluble NHase. Additionally, the biomaterial is significantly more stable at high concentrations of methanol (50% and 70%, v/v) as a co-solvent for the hydration of acrylonitrile than native PtNHase. These data indicate that PtNHase:sol–gel biomaterials can be used to develop new synthetic avenues involving nitriles as starting materials given that the conversion of the nitrile moiety to the corresponding amide occurs under mild temperature and pH conditions

    Japanese investment in U.S. real estate : status, trends and outlook

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    Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 204-214.by Russell C. Lindner and Edward L. Monahan, Jr.M.S

    Hiding in plain sight, Ficus desertorum (Moraceae), a new species of rock fig for Central Australia

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    A new species of lithophytic fig, Ficus desertorum B.C.Wilde & R.L.Barrett, endemic to arid Central Australia, is described and illustrated. It is distinguished from other species in Ficus section Malvanthera Corner by having stiff lanceolate, dark green, discolorous leaves; many parallel, often obscure lateral veins; petioles that are continuous with the midrib; with minute, usually white hairs and non- or slightly sunken intercostal regions on the lower surface. Previously included under broad concepts of either Ficus platypoda (Miq.) Miq. or Ficus brachypoda (Miq.) Miq., this species has a scattered distribution throughout Central Australia on rocky outcrops, jump-ups (mesas) and around waterholes. This culturally significant plant, colloquially referred to as the desert fig, grows on elevated landscapes in central Australia, including Uluru (Ayers Rock), Kata Tjuta (The Olgas) and Karlu Karlu (Devils Marbles), three of Central Australia’s best-known natural landmarks. Evidence is provided to show these plants are geographically and morphologically distinct from Ficus brachypoda, justifying the recognition of F. desertorum as a new species. Taxonomic issues with F. brachypoda and F. atricha D.J.Dixon are also discussed. Lectotypes are selected for Urostigma platypodum forma glabrior Miq. and Ficus platypoda var. minor Benth

    Bush Blitz collections and iNaturalist observations assist the recognition of a new species from New South Wales, Lomandra briggsiana (Asparagaceae)

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    A new species of Lomandra Labill., Lomandra briggsiana R.L.Barrett &amp; T.C.Wilson, is described from the Great Dividing Range and Western Slopes of New South Wales. The new species has affinity to the widespread south-eastern Australian species Lomandra multiflora (R.Br.) Britten, and to L. decomposita (R.Br.) Jian Wang ter &amp; A.R.Bean and Lomandra ramosissima Jian Wang ter from Queensland. It has previously been included under L. multiflora as a ‘terete-leaved’ form in the Flora of New South Wales and recognised as Lomandra sp. Oxley Wild Rivers (T.M. Collins 924) on PlantNET. While the taxon has been known for some time, many of the existing collections are sterile or have only immature or old inflorescences present, and all but one of the collections represent only a single sex. Formal description has been prompted by the collection of fertile material during a Bush Blitz expedition in Oxley Wild Rivers National Park and good-quality photographs of flowering material posted on iNaturalist

    EC171 Stubble Mulch Farming

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    Extension circular 171 discusses the importance and details of stubble mulch farming
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