15,592 research outputs found
White primer permits a corrosion-resistant coating of minimum weight
White primer for coating 2219 aluminum alloy supplies a base for a top coating of enamel. A formulation of pigments and vehicle results in a primer with high corrosion resistance and minimum film thickness
Testing and evaluation of solid lubricants for gas bearings
The testing and results of testing solid film lubricants for gas lubricated bearing applications are reported. The tests simulated operational hazards of tilting pad gas bearings. The presence of a low coefficient of friction and the endurance of the solid film lubricant were the criteria for judging superior performance. All solid lubricants tested were applied to a plasma sprayed chrome oxide surface. Molybdenum disulfide and graphite fluoride were the solid lubricants tested; other test parameters included the method of application of the solid lubricant and the surface finish of the plasma sprayed coating. In general, the application of a solid film lubricant was found to significantly improve the coefficient of friction of the rubbing surfaces
Development of corrosion inhibiting white primer final report, 26 jun. - 30 nov. 1964
Corrosion resisting white prime
Structure formation by cosmic strings with a cosmological constant
Final published version.Comment: 4 Page
Curvature Constraints from the Causal Entropic Principle
Current cosmological observations indicate a preference for a cosmological
constant that is drastically smaller than what can be explained by conventional
particle physics. The Causal Entropic Principle (Bousso, {\it et al}.) provides
an alternative approach to anthropic attempts to predict our observed value of
the cosmological constant by calculating the entropy created within a causal
diamond. We have extended this work to use the Causal Entropic Principle to
predict the preferred curvature within the "multiverse". We have found that
values larger than are disfavored by more than 99.99% and a
peak value at and
for open universes. For universes that allow only positive curvature or both
positive and negative curvature, we find a correlation between curvature and
dark energy that leads to an extended region of preferred values. Our universe
is found to be disfavored to an extent depending the priors on curvature. We
also provide a comparison to previous anthropic constraints on open universes
and discuss future directions for this work.Comment: 5 pages, 3 Figure
Characterization of nanometer-sized, mechanically exfoliated graphene on the H-passivated Si(100) surface using scanning tunnelling microscopy
We have developed a method for depositing graphene monolayers and bilayers
with minimum lateral dimensions of 2-10 nm by the mechanical exfoliation of
graphite onto the Si(100)-2x1:H surface. Room temperature, ultra-high vacuum
(UHV) tunnelling spectroscopy measurements of nanometer-sized single-layer
graphene reveal a size dependent energy gap ranging from 0.1-1 eV. Furthermore,
the number of graphene layers can be directly determined from scanning
tunnelling microscopy (STM) topographic contours. This atomistic study provides
an experimental basis for probing the electronic structure of nanometer-sized
graphene which can assist the development of graphene-based nanoelectronics.Comment: Accepted for publication in Nanotechnolog
Cosmic Strings in an Open Universe with Baryonic and Non-Baryonic Dark Matter
We study the effects of cosmic strings on structure formation in open
universes. We calculate the power spectrum of density perturbations for two
class of models: one in which all the dark matter is non baryonic (CDM) and one
in which it is all baryonic (BDM). Our results are compared to the 1 in 6 IRAS
QDOT power spectrum. The best candidates are then used to estimate , the
energy per unit length of the string network. Some comments are made on
mechanisms by which structures are formed in the two theories.Comment: uu-encoded compressed tar of postscript files, Imperial/TP/94-95/0
Optical diode based on the chirality of guided photons
Photons are nonchiral particles: their handedness can be both left and right.
However, when light is transversely confined, it can locally exhibit a
transverse spin whose orientation is fixed by the propagation direction of the
photons. Confined photons thus have chiral character. Here, we employ this to
demonstrate nonreciprocal transmission of light at the single-photon level
through a silica nanofibre in two experimental schemes. We either use an
ensemble of spin-polarised atoms that is weakly coupled to the nanofibre-guided
mode or a single spin-polarised atom strongly coupled to the nanofibre via a
whispering-gallery-mode resonator. We simultaneously achieve high optical
isolation and high forward transmission. Both are controlled by the internal
atomic state. The resulting optical diode is the first example of a new class
of nonreciprocal nanophotonic devices which exploit the chirality of confined
photons and which are, in principle, suitable for quantum information
processing and future quantum optical networks
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