71,983 research outputs found
Decomposition unit Patent
Unit for generating thrust from catalytic decomposition of hydrogen peroxide, for high altitude aircraft or spacecraft reaction contro
The Moduli Space and Phase Structure of Heterotic Strings in Two Dimensions
We explore the moduli space of heterotic strings in two dimensions. In doing
so, we introduce new lines of compactified theories with Spin(24) gauge
symmetry and discuss compactifications with Wilson lines. The phase structure
of d=2 heterotic string theory is examined by classifying the hypersurfaces in
moduli space which support massless quanta or discrete states. Finally, we
compute the torus amplitude over much of the moduli space.Comment: 23 pages, 1 figure, harvmac.tex; v2: minor changes to introduction,
version to be published in Phys. Rev.
Rolling contact fatigue life of chromium ion plated 440C bearing steel
Rolling contact fatigue (RCF) test specimens of heat treated 440C bearing steel were chromium ion plated in thicknesses from 0.1 to 8.0 micron and tested in RCF tester using 700 ksi maximum Hertzian stress. Heavy coatings, greater than about 5 micron in thickness, peeled off or spalled readily, whereas thin coatings, less than 3 micron thick, were tenacious and did not come off. Furthermore, significant improvement in RCF life was obtained with thin chromium ion plated test specimens. The average increase in B10 life was 75% compared with unplated 440C. These preliminary results indicate that ion plating is a promising way to improve bearing life
Specific Heat of Disordered He
Porous aerogel is a source of elastic scattering in superfluid 3He and
modifies the properties of the superfluid, suppressing the transition
temperature and order parameter. The specific heat jumps for the B-phase of
superfluid 3He in aerogel have been measured as a function of pressure and
interpreted using the homogeneous and inhomogeneous isotropic scattering
models. The specific heat jumps for other p-wave states are estimated for
comparison.Comment: Manuscript prepared for LT 2
Water Vapour Effects in Mass Measurement
Water vapour inside the mass comparator enclosure is a critical parameter. In
fact, fluctuations of this parameter during mass weighing can lead to errors in
the determination of an unknown mass. To control that, a proposal method is
given and tested. Preliminary results of our observation of water vapour
sorption and desorption processes from walls and mass standard are reported
Debris/ice/TPS assessment and integrated photographic analysis for Shuttle Mission STS-54
A Debris/Ice/TPS assessment and integrated photographic analysis was conducted for Shuttle Mission STS-54. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/TPS conditions and integrated photographic analysis of Shuttle Mission STS-54, and the resulting effect on the Space Shuttle Program
Debris/ice/TPS assessment and integrated photographic analysis for Shuttle Mission STS-46
A Debris/Ice/TPS assessment and integrated photographic analysis was conducted for Shuttle Mission STS-46. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/TPS conditions and integrated photographic analysis of Shuttle Mission STS-46, and the resulting effect on the Space Shuttle Program
Debris/ice/TPS assessment and photographic analysis for Shuttle Mission STS-42
A Debris/Ice/TPS (Thermal Protection System) assessment and photographic analysis was conducted for Shuttle Mission STS-42. Debris inspection of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flighr anomalies. The debris/ice/TPS conditions are documented along with photographic analysis of Mission STS-42, and their overall effect on the Space Shuttle Program
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