37,437 research outputs found
Expulsion bladder-equipped storage tank structure Patent
Expulsion bladder equipped storage tank structur
The linear boom actuator designed for the Galileo spacecraft
Because the linear boom actuator is to be used on a flight spacecraft, as opposed to a ground based application, there is a comprehensive set of requirements. First, of course, the actuator must be capable of positioning and holding the load. Initially the load as predicted to be 4448 N (1000 lb) but with subsequent spacecraft configuration changes the load has been greatly reduced to a constant tensile pull of 1477 N (332 lb) due to centrifugal force. Lesser compressive loads of 1317 N (296 centrifugal lb) may be experienced during launch and deployment. This actuator must have the maximum redundancy possible. Life requirements were defined by the 10.16 to 15.24 cm (4 to 6 in.) total liner travel expected during the five-year flight duration. Liner range required of the actuator was set at plus and minus 5.08 cm to accommodate configuration changes
Remotely operated gas-pressure regulator and shuttle valve
Valve features precise gas-pressure regulation and shuts off flow by remote control. Valve is made up of regulator valve cavity and spring-compression adjusts cavity. Elements in regulator cavity are conventional and include high-pressure inlet, ball which mates with seat, push rod, and pressure-sensing diaphragm
Combined pressure regulator and shutoff valve
A remotely operable pressure regulator and shutoff valve particularly suited for achieving high resolution and flow control, and positive shutoff is described. The valve is characterized by a spring-loaded ball coaxially aligned with a fluid port to be sealed, a spring-loaded pintle extended through the port into engagement with the ball, for controlling the position, a spring-loaded diaphragm for controlling the position of the pintle, and an axially displaceable spring supported by a movable stop which, in turn, is repositioned by a selectively operable stepper motor. Thus, the pressure-response characteristics for the valve can be varied through a selective repositioning of the stop
R-process and alpha-elements in the Galactic disk: Kinematic correlations
Recent studies of elemental abundances in the Galactic halo and in the
Galactic disk have underscored the possibility to kinematically separate
different Galactic subcomponents. Correlations between the galactocentric
rotation velocity and various element ratios were found, providing an important
means to link different tracers of star formation and metal enrichment to the
Galactic components of different origin (collapse vs. accretion). In the
present work we determine stellar kinematics for a sample of 124 disk stars,
which we derive from their orbits based on radial velocities and proper motions
from the the literature. Our stars form a subsample of the Edvardsson et al.
(1993) sample and we concentrate on three main tracers: (i) Europium as an
r-process element is predominantly produced in Supernovae of type II. (ii)
Likewise, alpha-elements, such as Ca, Si, Mg, are synthesised in SNe II,
contrary to iron, which is being produced preferentially in SNe Ia. (iii) The
s-process element Barium is a measure of the relative contribution of AGB stars
to the Galaxy's enrichment history and has been shown to be an indicator for
distinguishing between thin and thick disk stars. All such studies reveal,
basically, that stars with low galactocentric rotational velocity tend to have
high abundances of alpha-elements and Eu, but lower abundances of, e.g., Ba.Comment: 5 pages, 2 figures, Poster contribution to appear in "Planets To
Cosmology: Essential Science In Hubble's Final Years", proceedings of the May
2004 STScI Symposium, M. Livio (ed.), (Cambridge University Press
Remotely operated gripper provides vertical control rod movement
Remote actuation of a gripper shaft affects vertical engagement between a drive shaft and control rod. A secondary function of the gripper is to provide remote indication of positive completion of the gripping or ungripping operation
Discrete Hubbard-Stratonovich transformations for systems with orbital degeneracy
A discrete Hubbard-Stratonovich transformation is presented for systems with
an orbital degeneracy and a Hubbard Coulomb interaction without multiplet
effects. An exact transformation is obtained by introducing an external field
which takes values. Alternative approximate transformations are
presented, where the field takes fewer values, for instance two values
corresponding to an Ising spin.Comment: 4 pages, revtex, 1 eps figure, additional material avalable at
http://librix.mpi-stuttgart.mpg.de/docs/ANDERSEN/fullerene
Analysis of pressure distortion testing
The development of a distortion methodology, method D, was documented, and its application to steady state and unsteady data was demonstrated. Three methodologies based upon DIDENT, a NASA-LeRC distortion methodology based upon the parallel compressor model, were investigated by applying them to a set of steady state data. The best formulation was then applied to an independent data set. The good correlation achieved with this data set showed that method E, one of the above methodologies, is a viable concept. Unsteady data were analyzed by using the method E methodology. This analysis pointed out that the method E sensitivities are functions of pressure defect level as well as corrected speed and pattern
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