22,597 research outputs found
Docking and retrieval mechanism
An engineering prototype docking and retrieval mechanism (DRM) which enables two spacecraft to dock and be structurally joined on-orbit is described. The joining of two spacecraft or payloads on-orbit supports future planned space activities such as payload servicing, deployment and retrieval, and assembly or large space systems. Advantages of the DRM include: it is a nonimpact docking mechanism; does not require impact absorbing mechanisms or attitude stabilization on the target spacecraft; is capable of docking to a spinning spacecraft; and can spin up and deploy a spinning spacecraft or payload
Safety shield for vacuum/pressure chamber viewing port
Observers are protected from flying debris resulting from a failure of a vacuum or pressure chamber viewing port following an implosion or explosion by an optically clear shatter resistant safety shield which spaced apart from the viewing port on the outer surface of the chamber
Review and analysis of the DNW/Model 360 rotor acoustic data base
A comprehensive model rotor aeroacoustic data base was collected in a large anechoic wind tunnel in 1986. Twenty-six microphones were positioned around the azimuth to collect acoustic data for approximately 150 different test conditions. A dynamically scaled, blade-pressure-instrumented model of the forward rotor of the BH360 helicopter simultaneously provided blade pressures for correlation with the acoustic data. High-speed impulsive noise, blade-vortex interaction noise, low-frequency noise, and broadband noise were all captured in this extensive data base. Trends are presentes for each noise source, with important parametric variations. The purpose of this paper is to introduce this data base and illustrate its potential for predictive code validation
A simplified holographic-interferometry technique for real-time flow visualization and analysis
A holographic-interferometry technique for flow visualization and analysis that produces real-time moire fringes is described from both experimental and application considerations. It has three chief advantages: real-time data for continuous observation and photography, ease of optical adjustment, and capability of using ordinary-glass test-section windows without affecting the results. A theoretical discussion is presented describing the formation of the fringes in holographic terms and then comparing this result to that which is obtained from a conventional moire approach. A discussion on obtaining density information from the fringe pattern is also included
An evaluation of relationships between fatigue and depression in patients with chronic obstructive pulmonary disease
Loki, Io: New groundbased observations and a model describing the change from periodic overturn
Loki Patera is the most powerful volcano in the solar system. We have
obtained measurements of Loki's 3.5 micron brightness from NASA's Infrared
Telescope Facility (IRTF) and have witnessed a change from the periodic
behavior previously noted. While Loki brightened by a factor of several every
540 days prior to 2001, from 2001 through 2004 Loki remained at a constant,
medium brightness. We have constructed a quantitative model of Loki as a
basaltic lava lake whose solidified crust overturns when it becomes buoyantly
unstable. By altering the speed at which the overturn propagates across the
patera, we can match our groundbased brightness data. In addition, we can match
other data taken at other times and wavelengths. By slowing the propagation
speed dramatically, we can match the observations from 2001-2004. This slowing
may be due to a small change in volatile content in the magma
The Modular Temperley-Lieb Algebra
We investigate the representation theory of the Temperley-Lieb algebra,
, defined over a field of positive characteristic. The principle
question we seek to answer is the multiplicity of simple modules in cell
modules for over arbitrary rings. This provides us with the
decomposition numbers for this algebra, as well as the dimensions of all simple
modules. We obtain these results from diagrammatic principles, without
appealing to realisations of as endomorphism algebras of
modules.Comment: 27 pages, fix typo
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