6,379 research outputs found

    Gas turbine engine with convertible accessories

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    Drive means for connecting a gas turbine engine to its accessories are so constructed as to allow the accessories to be selectively positioned to any one of several predetermined circumferential positions about the perimeter of the engine. This feature permits convenient mounting of the same engine upon vehicles demanding radically different engine mounting arrangements

    Barium cloud evolution and striation formation in the magnetospheric release on September 21, 1971

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    The joint NASA-Max Planck Institute Barium Ion Cloud (BIC) Experiment on September 21, 1971 involved the release of 1.7 kg of neutral barium at an altitude of 31,500 km at a latitude of 6.93 deg N. and a longitude of 74.40 deg W. A theoretical model describing the barium neutral cloud expansion and the ion cloud formation is developed. The mechanism of formation of the striational features observed in the release is also discussed. Two candidate instabilities, which may contribute to striation formation, are examined. The drift instability stemming from the outwardly directed drag force exerted on the ions by the outstreaming neutrals is rejected on the grounds that the ion density is too low during the collision-dominated phase of the cloud expansion to support this kind of instability. The joint action of Rayleigh-Taylor and flute instabilities plausibly accounts for the observed striational structure. This same mechanism may well be operative at times of sudden injection of plasma into the inner magnetosphere during geomagnetic storms and may thus contribute to the formation of field-alined inhomogeneities which serve as whistler ducts

    The Basin Plan, the buy-back and climate change: determining an optimal water entitlements portfolio

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    The theme for 2012 was 'Water and climate: policy implementation challenges'.The long-term success of the Basin Plan and the Buy-Back will be judged by the capacity of the allocated public funding to deliver water to the environment, potable water supplies for the community and water for irrigation. Water property rights in the Murray-Darling Basin can be divided into four distinct groups (ground water, high security, general security and supplementary) reflecting their inherent capacity to deliver water supplies in response to climatic conditions in a given year. The price paid for these entitlements reflects their ability to provide water under known climate variability. The optimal portfolio of water entitlements needs to encapsulate this information in order to determine which entitlements to purchase, the number needed and their location in the river system in order to deliver net social benefits. The optimal portfolio of entitlements is further complicated by the climate transitioning from a known mean and variance to a new mean and variance. The spatial impact of climate change on water resources is not uniform. Hence what is seen as a good portfolio now may in fact be sub-optimal in the future. The aim of this paper is to illustrate the benefits of a state contingent framework for describing the optimal portfolio of water entitlements under a changing climate. By explicitly determining the real value of water entitlements in normal, drought and wet states of nature, we can determine the Buy- Back’s ability to achieve the Basin Plan’s goals and suggest an optimal entitlement mix to deliver long- term economic, social and environmental benefits under climate change.D. Adamso

    The 3 micron spectrum of NGC 4565

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    Researchers spectrum of NGC 4565 is essentially featureless. The absence of the 3.0 micron feature (Tau 3.0 less than 0.05) implies that the extinction to the nucleus does not arise to a significant degree in molecular clouds. Researchers deduce Tau 3.0/A sub V less than 0.01, compared with approx. 0.022 for GC-IRS7. These results support the conclusion (McFadzean et al. 1989) that the 3.0 micron absorption in the GC-IR sources is due to the presence of ice in a (probably single) foreground molecular cloud. The 3.4 micron feature is also weak or absent in the researchers spectrum of NGC 4565 (Tau 3.4 less than or equal to 0.07), hence, Tau 3.4/A sub V less than or equal to 0.016, compared with approx. 0.008 towards GC-IRS7. The absence of the feature in NGC 4565 at the signal-to-noise level of the current observations is consistent with a probable moderate degree of extinction towards the nucleus. The observations of NGC 4565 provide a useful comparison for studies of dust in the Galaxy. Limits have been set on the strengths of the 3.0 and 3.4 micron features in NGC 4565. The absence of 3.0 micron absorption is significant, and supports the view that the feature at this wavelength in the Galactic Centre is due to water-ice absorption in a foreground molecular cloud. The non-detection of the 3.4 micron absorption is less surprising and provides indirect support for the association between this feature and the diffuse interstellar medium. The current spectrum probably represents the best that can be achieved with a single-detector instrument within reasonable integration times. It will clearly be of interest in the future to obtain spectra of higher signal-to-noise, as a positive detection of the 3.4 micron feature in an external galaxy, even at a low level, would be of considerable astrophysical significance

    Integrated gas turbine engine-nacelle

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    A nacelle for use with a gas turbine engine is provided with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus, while the outer surface of the nacelle defines a streamlined envelope for the engine

    Integrated gas turbine engine-nacelle

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    A nacelle for use with a gas turbine engine is presented. An integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine, provides lightweight support. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus while the outer surface of the nacelle defines a streamlined envelope for the engine

    Strategic Positioning of United States Air Force Civil Engineer Contingency Equipment within the Supply Chain

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    The consolidation and forward positioning of critical inventories often provides substantial benefits over a geographically dispersed posture. Such benefits include, but are not limited to: increased inventory visibility, reduced transportation costs, and fewer manpower requirements. Presently, the United States Air Force (USAF) Civil Engineer (CE) community maintains a disseminated posture of equipment Unit Type Codes (UTCs), which regularly experiences inconsistencies in handling, tracking, and capability reporting. Provided the aforementioned discrepancies, this research effort examines several aspects surrounding the decision to potentially centralize critical CE inventories to either one or two locations. Specifically, the areas of cost, risk, and manpower are scrutinized to facilitate an objective decision by USAF CE senior leaders on whether or not to pursue an alternative equipment posture. Three scholarly articles are presented covering each area of interest and data supported recommendations are provided. The research offers insight concerning the decision of inventory consolidation as well as available methods to facilitate such a determination

    The Salt Lake Group in Cache Valley, Utah and Idaho

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    Fluvial and lacustrine sediments of great thickness accumulated in the intermountain basins of the western United States during Tertiary time. The Salt Lake group in northern Utah and parts of surrounding states is a conspicuous stratigraphic unit of these basins. The beds of light color in Morgan Valley in the Wasatch Mountains of northern Utah were named the Salt Lake group by Hayden (1869) because of similar occurrences in Salt Lake Valley and because he reasoned that the succession could be divided into formations. Similar rocks crop out in Ogden Valley, north of Morgan Valley, and in Cache Valley, Utah and Idaho. Cache Valley is bounded by the Wasatch and Malad Ranges to the west and the Bear River Range to the east (Fig. 1). It extends from the divide between Ogden and Cache valleys about 18 miles south of Los an. Utah. to Red Rock Pass. about 19 miles northwest of Preston. Idaho. The Bear River enters Cache Valley northeast of Preston. Idaho. and leaves through the Bear River Narrows west of Logan. Utah. at a point between the northern end of the Wasatch Range and the Malad Range. Red Rock Pass, northwest of Preston, Idaho, was the outlet of Lake Bonneville

    Results of magnetospheric barium ion cloud experiment of 1971

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    The barium ion cloud experiment involved the release of about 2 kg of barium at an altitude of 31 482 km, a latitude of 6.926 N., and a longitude of 74.395 W. Significant erosion of plasma from the main ion core occurred during the initial phase of the ion cloud expansion. From the motion of the outermost striational filaments, the electric field components were determined to be 0.19 mV/m in the westerly direction and 0.68 mV/m in the inward direction. The differences between these components and those measured from balloons flown in the proximity of the extremity of the field line through the release point implied the existence of potential gradients along the magnetic field lines. The deceleration of the main core was greater than theoretically predicted. This was attributed to the formation of a polarization wake, resulting in an increase of the area of interaction and resistive dissipation at ionospheric levels. The actual orientation of the magnetic field line through the release point differed by about 10.5 deg from that predicted by magnetic field models that did not include the effect of ring current
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