7,574 research outputs found
Wind tunnel tests of Space Shuttle external tank insulation material in the aerothermal tunnel at elevated (1440 deg F) total temperatures
Tests of the space shuttle external tank foam insulation were conducted in the von Karman Gas Dynamics Facility Tunnel C. For these tests, Tunnel C was run at Mach 4 with a total temperature of 1440 F and a total pressure which varied from 30-100 psia. Cold wall heating rates were changed by varying the test article support wedge angle and by adding and removing a shock generator or a cylindrical protuberance. Selected results are presented to illustrate the test techniques and typical data obtained
A Plan of Farm Organization for Hill Land Farms in Southeastern Ohio
Exact date of bulletin unknown.PDF pages: 2
Rational approximation and arithmetic progressions
A reasonably complete theory of the approximation of an irrational by
rational fractions whose numerators and denominators lie in prescribed
arithmetic progressions is developed in this paper. Results are both, on the
one hand, from a metrical and a non-metrical point of view and, on the other
hand, from an asymptotic and also a uniform point of view. The principal
novelty is a Khintchine type theorem for uniform approximation in this context.
Some applications of this theory are also discussed
Simulation of MeV/atom cluster correlations in matter
We present an efficient algorithm able to predict the trajectories of individual cluster constituents as they penetrate relatively thick amorphous targets. Our algorithm properly treats both the intracluster Coulomb repulsion and the collisions between cluster constituents and target atoms. We have compared our simulation predictions to experimental measurements of the distribution of lateral exit velocities, and demonstrated that the in-target Coulomb explosion of 2MeV/atom carbon clusters in carbon foils must be shielded with a screening length of less than 2.5 Å. We also present a simple phenomenological model for the suppression of the exit-side charge of ions in clusters which depends on the enhanced ionization potential that an electron near an ion feels due to the ion’s charged comoving neighbors. By using our simulation algorithm we have predicted the exit correlations of the cluster constituents and verified that the charge suppression model fits the observed charge suppression of ions in clusters to within the experimental uncertainties
Wind tunnel tests of space shuttle solid rocket booster insulation material in the aerothermal tunnel c
Wind tunnel tests of the space shuttle Solid Rocket Booster Insulation were conducted in the von Karman Gas Dynamics Facility Tunnel C. For these tests, Tunnel C was run at Mach 4 with a total temperature of 1100-1440 and a total pressure of 100 psia. Cold wall heating rates were changed by varying the test article support wedge angle. Selected results are presented to illustrate the test techniques and typical data obtained
Superconducting Hair on Charged Black String Background
Behaviour of Dirac fermions in the background of a charged black string
penetrated by an Abelian Higgs vortex is elaborated. One finds the evidence
that the system under consideration can support fermion fields acting like a
superconducting cosmic string in the sence that a nontrivial Dirac fermion
field can be carried by the system in question. The case of nonextremal and
extremal black string vortex systems were considered. The influence of electric
and Higgs charge, the winding number and the fermion mass on the fermion
localization near the black string event horizon was studied. It turned out
that the extreme charged black string expelled fermion fields more violently
comparing to the nonextremal one.Comment: RevTex, 16 pages, 12 figures, to be published in Phys.REvD1
New Capacitive-Array Sensors for Post-Process Cure Verification and NDE of Polymers and Composites
A new capacitive array sensor has been developed for process verification and NDE of polymers and composites. Unlike existing dielectrometer technology, the new sensor incorporates several innovations to maximize sensitivity to material properties while minimizing the effects of temperature, humidity and electromagnetic interference. Conventional dielectric measurement systems require sensors to be embedded within a material and discarded after a single use. Furthermore, conventional sensors are so sensitive to environmental variables that cure monitoring is based solely on changes in the material ionic conductivity; no absolute measure of cure state is possible. The configuration of these new sensors greatly reduces sensitivity to environmental variables and permits external, rather than embedded, measurement making both post-process cure verification and NDE possible. Since the sensor is not discarded, the cost per measurement is greatly reduced
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