2,078 research outputs found
Electrically conductive thermal control coatings
A coating characterized by low thermal absorption, high thermal emittance and high electrical conductivity comprises: (1) a fired oxide pigment comprising a minor amount of aluminum oxide and a major amount of zinc oxide; (2) sufficient water to provide a mixture suitable for application to a substrate, is presented. The fired oxide pigment may further include a minor amount of cobalt oxide. The resulting coating is particularly useful for coating the surfaces of spacecraft and similar objects
AdS/CFT for Unprotected Operators
We consider the four-point function of the lowest scalar in the stress-energy
tensor multiplet in ABJ(M) theory \cite{Aharony:2008ug,
Aharony:2008gk}. At large central charge , this correlator is
given by the corresponding holographic correlation function in 11d supergravity
on . We use Mellin space techniques to compute the leading
correction to anomalous dimensions and OPE coefficients of operators
that appear in this holographic correlator. For half and quarter-BPS operators,
we find exact agreement with previously computed localization results. For the
other BPS and non-BPS operators, our results match the
numerical bootstrap for ABJ(M) at large , which provides a precise check
of unprotected observables in AdS/CFT.Comment: 22 pages, 1 figure, v4, fixed typo
Formulation of electrically conductive thermal-control coatings
The development and formulation of electrically conductive thermal control coating was undertaken for use on the International Sun Earth Explorer spacecraft. The primary effort was to develop a coating with a bulk resistivity of less than 100,000 ohm/sqm, an optical absorptance of approximately 0.55, and a normal emittance of 0.90. The required stability in space called for a bulk resistivity of less than 100,000 ohm/sq m, an absorptance of less than 0.67, and a normal emittance of 0.90 after exposure to approximately 4 x 10 to the 16th proton/sq cm of solar-wind particles and 5300 equivalent sun-hours. These exposures represent 2 years of ISEE flight conditions. Both the unsuccessful formulation efforts and the successful use of oxide pigments fired at 1448 K are described. Problems relative to the reactivity of specific coating vehicles exposed to high humidity are discussed
M-Theory Reconstruction from (2,0) CFT and the Chiral Algebra Conjecture
We study various aspects of the M-theory uplift of the series of
CFTs in 6d, which describe the worldvolume theory of M5 branes in
flat space. We show how knowledge of OPE coefficients and scaling dimensions
for this CFT can be directly translated into features of the momentum expansion
of M-theory. In particular, we develop the expansion of the four-graviton
S-matrix in M-theory via the flat space limit of four-point Mellin amplitudes.
This includes correctly reproducing the known contribution of the term
from 6d CFT data. Central to the calculation are the OPE coefficients for
half-BPS operators not in the stress tensor multiplet, which we obtain for
finite via the previously conjectured relation [arXiv:1404.1079] between
the quantum algebra and the CFT. We further
explain how the expansion of structure constants exhibits
the structure of protected vertices in the M-theory action. Conversely, our
results provide strong evidence for the chiral algebra conjecture.Comment: 30+18 pages. v2: added refs, fixed typos/notatio
Diffusely reflecting paints including polytetrafluoroethylene and method of manufacture
The invention pertains to a high diffuse, reflective paint comprising an alcohol soluble binder, polytetrafluoroethylene (TFE) and an alcohol for coating a substrate and forming an optical reference with a superior Lambertian characteristic. A method for making the paint by first mixing the biner and alcohol, and thereafter by mixing in outgassed TFE is described. A wetting agent may be employed to aid the mixing process
Towards Bootstrapping QED
We initiate the conformal bootstrap study of Quantum Electrodynamics in
space-time dimensions (QED) with flavors of charged fermions by
focusing on the 4-point function of four monopole operators with the lowest
unit of topological charge. We obtain upper bounds on the scaling dimension of
the doubly-charged monopole operator, with and without assuming other gaps in
the operator spectrum. Intriguingly, we find a (gap-dependent) kink in these
bounds that comes reasonably close to the large extrapolation of the
scaling dimensions of the singly-charged and doubly-charged monopole operators
down to and .Comment: 29 pages plus an appendix, 5 figures, v2 minor improvements, refs
adde
Formulation of MS-74 white thermal-control coating and revised application procedures
Procedures are given for formulating, blending, and applying MS-74 white thermal-control coating and CC-1 primer to spacecraft structures. Improved ultraviolet stability, higher emittance and low absorptivity, and enhanced adhesion characteristics result from the revised procedures
Alkali metal silicate protective coating Patent
Composition and production method of alkali metal silicate paint with ultraviolet reflection propertie
Black silicate paints: Formulation and performance data on OSO-H
Formulations and general procedures are given for making and applying space environmentally, as well as atmospherically stable black silicate paints. Compositions are given which meet spacecraft self-contamination requirements, have excellent heat resistance, and are strongly semiconductive
Formulation procedures, rationale, and preliminary IMP-H flight data for silicone paints with improved stability
Results are given of a class of silicone paints undergoing space qualification on IMP-H. In addition to ultraviolet irradiation, samples are presently reclining about 10 to the 16th power solar wind protons per year. Preliminary data, covering the time span of the first anniversary, give incremental solar absorptances of 0.03 for two white paints, and 0.01 for leafing aluminum and a green tinted white paint. Complementing these data are complete descriptions of techniques used in making these paints, stabilizing the zinc oxide pigment, and choosing a solvent. Outgassing characteristics of finished coatings are also included. An attempt toward unification of these various aspects of the aerospace paint problem is provided through documented photochemical reactions, and a generalized band representation of the problem and its solutions
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