510 research outputs found

    Design of an autonomous teleoperated cargo transporting vehicle for lunar base operations

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    At the turn of the century NASA plans to begin construction of a lunar base. The base will likely consist of developed areas (i.e., habitation, laboratory, landing and launching sites, power plant) separated from each other due to safety considerations. The Self-Repositioning Track Vehicle (SRTV) was designed to transport cargo between these base facilities. The SRTV operates by using two robotic arms to raise and position segments of track upon which the vehicle travels. The SRTV utilizes the semiautonomous mobility (SAM) method of teleoperation; actuator-controlled interlocking track sections; two robotic arms each with five degrees of freedom; and these materials: titanium for structural members and aluminum for shell members, with the possible use of light-weight, high-strength composites

    Left-invariant almost complex structures on the higher dimensional Kodaira-Thurston manifolds

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    We develop computational techniques which allow us to calculate the Kodaira dimension as well as the dimension of spaces of Dolbeault harmonic forms for left-invariant almost complex structures on the generalised Kodaira-Thurston manifolds.Comment: 15 pages, comments are welcom

    Cold and Warm Gas Outflows in Radio AGN

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    The study of the conditions and the kinematics of the gas in the central region of AGN provides important information on the relevance of feedback effects connected to the nuclear activity. Quantifying these effects is key for constraining galaxy evolution models. Here we present a short summary of our recent efforts to study the occurrence and the impact of gas outflows in radio-loud AGN that are in their first phase of their evolution. Clear evidence for AGN-induced outflows have been found for the majority of these young radio sources. The outflows are detected both in (warm) ionized as well in (cold) atomic neutral gas and they are likely to be driven (at least in most of the cases) by the interaction between the expanding jet and the medium. The mass outflow rates of the cold gas (HI) appear to be systematically higher than those of the ionized gas. The former reach up to ~50 Msun/yr, and are in the same range as "mild" starburst-driven superwinds in ULIRGs, whilst the latter are currently estimated to be a few solar masses per year. However, the kinetic powers associated with these gaseous outflow are a relatively small fraction (a few x 10^-4) of the Eddington luminosity of the galaxy. Thus, they do not appear to match the requirements of the galaxy evolution feedback models.Comment: Invited talk, to appear in the Proceedings of the IAU Symposium 267, "Co-Evolution of Central Black Holes and Galaxies", B.M. Peterson, R.S. Somerville, T. Storchi-Bergmann, eds., in pres

    Glaciological and geomorphological map of Glacier Noir and Glacier Blanc, French Alps

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    <p>This paper presents and describes a glaciological and geomorphological map of Glacier Noir and Glacier Blanc, French Alps. Glacier Noir is a debris-covered glacier and is adjacent to Glacier Blanc, a clean-ice (debris-free) glacier. The glaciological and geomorphological evolution of Glacier Blanc is well known, but the evolution of Glacier Noir is poorly understood, as is the case for many debris-covered glaciers globally, despite their importance in a number of mountain ranges around the world (e.g. European and Southern Alps, the Himalayas and the Rockies). The accompanying map was created by manually digitising aerial ortho-images and historical georeferenced photographs from 1952 to 2013. The main glacial and geomorphological features of both glaciers were mapped, including debris cover, crevasses, moraines, hummocky terrain and scree areas. Hydrological features (supra- and pro-glacial streams and meltwater ponds) were also mapped. The map illustrates the key differences between Glacier Noir and Glacier Blanc, and is important for understanding future glaciological and geomorphological changes.</p

    Ice shelf history determined from deformation styles in surface debris

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    AbstractThis paper presents InSAR-derived ice shelf velocities and observations of surface debris deformation on the McMurdo Ice Shelf (MIS). Ice shelf velocities show that the MIS has a low surface velocity, with debris-laden parts of the ice shelf in the area known as the ‘swirls’ averaging speeds of c. 3 m a-1 increasing to c. 16 m a-1 at the ice front. Analysis of the fold patterns within moraine ridges on the ice surface reveals a deformational history inconsistent with the present velocity measurements. Polyphase, isoclinal folding within moraine ridges at the surface are interpreted to have formed through intense deformation by past ice flow in a NNW orientation. The velocities and styles of deformation indicate that the majority of debris on the ice shelf was originally transported into the area by a large and dynamic ice sheet/ice shelf system entirely different to that of the present configuration. Although the age of this event is unknown, it is possible that this debris has been exposed on the surface of the ice shelf since the last glacial maximum.</jats:p