5,109 research outputs found
Redundant actuator development study
Current and past supersonic transport configurations are reviewed to assess redundancy requirements for future airplane control systems. Secondary actuators used in stability augmentation systems will probably be the most critical actuator application and require the highest level of redundancy. Two methods of actuator redundancy mechanization have been recommended for further study. Math models of the recommended systems have been developed for use in future computer simulations. A long range plan has been formulated for actuator hardware development and testing in conjunction with the NASA Flight Simulator for Advanced Aircraft
High-resolution UKIRT observations of circumnuclear star formation in M100
We present high-resolution, near-infrared imaging of the circumnuclear region
of the barred spiral galaxy M100 (=NGC 4321), accompanied by near-infrared
spectroscopy. We identify a total of 43 distinct regions in the K-band image,
and determine magnitudes and colours for 41 of them. By comparison with other
near-infrared maps we also derive colour excesses and K-band extinctions for
the knots. Combining the imaging and spectroscopic results, we conclude that
the knots are the result of bursts of star formation within the last 15-25 Myr.
We discuss the implications of these new results for our dynamical and
evolutionary understanding of this galaxy.Comment: 10 pages, 4 figures, uses mn-1.4.sty. Accepted for publication in
Monthly Notices of the Royal Astronomical Societ
Proca equations derived from first principles
Gersten has shown how Maxwell equations can be derived from first principles,
similar to those which have been used to obtain the Dirac relativistic electron
equation. We show how Proca equations can be also deduced from first
principles, similar to those which have been used to find Dirac and Maxwell
equations. Contrary to Maxwell equations, it is necessary to introduce a
potential in order to transform a second order differential equation, as the
Klein-Gordon equation, into a first order differential equation, like Proca
equations.Comment: 6 page
Redundancy of hydraulic flight control actuators
The constraint of requiring airplanes to have inherent aerodynamic stability can be removed by using active control systems. The resulting airplane requires control system reliability approaching that of the basic airframe. Redundant control actuators can be used to achieve the required reliability, but create mechanization and operational problems. Of numerous candidate systems, two different approaches to solving the problems associated with redundant actuators which appear the most likely to be used in advanced airplane control systems are described
A postmortem investigation of the Type IIb supernova 2001ig
We present images taken with the GMOS instrument on Gemini-South, in
excellent (<0.5 arcsec) seeing, of SN 2001ig in NGC 7424, ~1000 days after
explosion. A point source seen at the site of the SN is shown to have colours
inconsistent with being an H II region or a SN 1993J-like remnant, but can be
matched to a late-B through late-F supergiant with A_V<1. We believe this
object is the massive binary companion responsible for periodic modulation in
mass loss material around the Wolf-Rayet progenitor which gave rise to
significant structure in the SN radio light curve.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS Letters. Fig. 1
resolution degraded to meet size limitations; full resolution version
available from http://www.aao.gov.au/local/www/sdr/pubs/sn2001ig_gmos.ps.g
Workshop on Geology of the Apollo 17 Landing Site
The topics covered include the following: petrology, lithology, lunar rocks, lunar soil, geochemistry, lunar geology, lunar resources, oxygen production, ilmenite, volcanism, highlands, lunar maria, massifs, impact melts, breccias, lunar crust, Taurus-Littrow, minerals, site selection, regolith, glasses, geomorphology, basalts, tectonics, planetary evolution, anorthosite, titanium oxides, chemical composition, and the Sudbury-Serenitatis analogy
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