19,796 research outputs found
Fluidized combustion of coal
A combustion technology that permits the burning of low quality coal, and other fuels, while maintaining stack emissions within State and Federal EPA limits is discussed. Low quality fuels can be burned directly in fluidized beds while taking advantage of low furnace temperatures and chemical activity within the bed to limit SO2 and NOx emissions. The excellent heat transfer characteristics of the fluidized beds also result in a reduction of total heat transfer surface requirements. Tests on beds operating at pressures of one to ten atmospheres, at temperatures as high as 1600 F, and with gas velocities in the vicinity of four to twelve feet per second, have proven the concept. The progress that has been made in the development of fluidized bed combustion technology and work currently underway are discussed
Automatic patient respiration failure detection system with wireless transmission
Automatic respiration failure detection system detects respiration failure in patients with a surgically implanted tracheostomy tube, and actuates an audible and/or visual alarm. The system incorporates a miniature radio transmitter so that the patient is unencumbered by wires yet can be monitored from a remote location
Miniature ingestible telemeter devices to measure deep-body temperature
A telemetry device comprised of a pill-size ingestible transmitter developed to obtain deep body temperature measurements of a human is described. The device has particular utility in the medical field where deep body temperatures provide an indication of general health
Zero gravity separator Patent
Describing apparatus for separating gas from cryogenic liquid under zero gravity and for venting gas from fuel tan
Protective encapsulation of implantable biotelemetry units
Development of materials for encapsulating electronic devices used in biotelemetry is discussed. Chemical resistance of materials to effects of animal fluids is described. Silicone rubber is recommended as basic material with polymers applied to outer surface for protective coating
Non-Abelian Black Holes in D=5 Maximal Gauged Supergravity
We investigate static non-abelian black hole solutions of anti-de Sitter
Einstein-Yang-Mills-Dilaton gravity, which is obtained as a consistent
truncation of five-dimensional maximal gauged supergravity. If the dilaton is
(consistently) set to zero, the remaining equations of motion, with a
spherically-symmetric ansatz, may be derived from a superpotential. The
associated first-order equations admit an explicit solution supported by a
non-abelian SU(2) gauge potential, which has a logarithmically growing mass
term. In an extremal limit the horizon geometry becomes AdS. If
the dilaton is also excited, the equations of motion cannot easily be solved
explicitly, but we obtain the asymptotic form of the more general non-abelian
black holes in this case. An alternative consistent truncation, in which the
Yang-Mills fields are set to zero, also admits a description in terms of a
superpotential. This allows us to construct explicit wormhole solutions
(neutral spherically-symmetric domain walls). These solutions may be
generalised to dimensions other than five.Comment: Author's address, and a reference, adde
Domain Walls and Massive Gauged Supergravity Potentials
We point out that massive gauged supergravity potentials, for example those
arising due to the massive breathing mode of sphere reductions in M-theory or
string theory, allow for supersymmetric (static) domain wall solutions which
are a hybrid of a Randall-Sundrum domain wall on one side, and a dilatonic
domain wall with a run-away dilaton on the other side. On the anti-de Sitter
(AdS) side, these walls have a repulsive gravity with an asymptotic region
corresponding to the Cauchy horizon, while on the other side the runaway
dilaton approaches the weak coupling regime and a non-singular attractive
gravity, with the asymptotic region corresponding to the boundary of spacetime.
We contrast these results with the situation for gauged supergravity potentials
for massless scalar modes, whose supersymmetric AdS extrema are generically
maxima, and there the asymptotic regime transverse to the wall corresponds to
the boundary of the AdS spacetime. We also comment on the possibility that the
massive breathing mode may, in the case of fundamental domain-wall sources,
stabilize such walls via a Goldberger-Wise mechanism.Comment: latex file, 11 pages, 3 figure
Consistent Kaluza-Klein Sphere Reductions
We study the circumstances under which a Kaluza-Klein reduction on an
n-sphere, with a massless truncation that includes all the Yang-Mills fields of
SO(n+1), can be consistent at the full non-linear level. We take as the
starting point a theory comprising a p-form field strength and (possibly) a
dilaton, coupled to gravity in the higher dimension D. We show that aside from
the previously-studied cases with (D,p)=(11,4) and (10,5) (associated with the
S^4 and S^7 reductions of D=11 supergravity, and the S^5 reduction of type IIB
supergravity), the only other possibilities that allow consistent reductions
are for p=2, reduced on S^2, and for p=3, reduced on S^3 or S^{D-3}. We
construct the fully non-linear Kaluza-Klein Ansatze in all these cases. In
particular, we obtain D=3, N=8, SO(8) and D=7, N=2, SO(4) gauged supergravities
from S^7 and S^3 reductions of N=1 supergravity in D=10.Comment: 27 pages, Latex, typo correcte
Entropy-Product Rules for Charged Rotating Black Holes
We study the universal nature of the product of the entropies of all horizons
of charged rotating black holes. We argue, by examining further explicit
examples, that when the maximum number of rotations and/or charges are turned
on, the entropy product is expressed in terms of angular momentum and/or
charges only, which are quantized. (In the case of gauged supergravities, the
entropy product depends on the gauge-coupling constant also.) In two-derivative
gravities, the notion of the "maximum number" of charges can be defined as
being sufficiently many non-zero charges that the Reissner-Nordstrom black hole
arises under an appropriate specialisation of the charges. (The definition can
be relaxed somewhat in charged AdS black holes in .) In
higher-derivative gravity, we use the charged rotating black hole in
Weyl-Maxwell gravity as an example for which the entropy product is still
quantized, but it is expressed in terms of the angular momentum only, with no
dependence on the charge. This suggests that the notion of maximum charges in
higher-derivative gravities requires further understanding.Comment: References added. 24 page
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