59,326 research outputs found
Boundary-Layer Similar Solutions for Equilibrium Dissociated Air and Application to the Calculation of Laminar Heat-Transfer Distribution on Blunt Bodies in High-Speed Flow
No abstract availabl
Decoherence and dephasing in strongly driven colliding Bose-Einstein condensates
We report on a series of measurements of decoherence and wavepacket dephasing
between two colliding, strongly coupled, identical Bose-Einstein condensates.
We measure, in the strong excitation regime, a suppression of the mean-field
shift, compared to the shift which is observed for a weak excitation. This
suppression is explained by applying the Gross-Pitaevskii energy functional. By
selectively counting only the non-decohered fraction in a time of flight image
we observe oscillations for which both inhomogeneous and Doppler broadening are
suppressed, in quantitative agreement with a full Gross-Pitaevskii equation
simulation. If no post selection is used, the decoherence rate due to
collisions can be extracted, and is in agreement with the local density average
calculated rate.Comment: 4 pages, 5 figure
First Results of the 74 MHz VLA-Pie Town Link. Hercules A at Low Frequencies
We present the results of the first successful observations of the Pie Town
link with the Very Large Array (VLA) at 74 MHz on Hercules A. The improvement
in resolution from 25 arcsec to 10 arcsec resolves the helical- and ring-like
features seen at higher frequencies. We also present new high dynamic range
images of this powerful radio galaxy at 325 MHz. Our low frequency observations
confirm the multiple outburst interpretation of the spectral index differences
at high frequencies. Comparison between our radio and ROSAT X-ray data does not
reveal any association between the X-ray emission from the cluster and the
radio lobes. There are no extra regions of radio emission at 74 MHz.Comment: 9 pages, 7 figures, accepted for publication in MNRA
Splitting in the Excitation Spectrum of A Bose-Einstein Condensate Undergoing Strong Rabi Oscillations
We report on a measurement of splitting in the excitation spectrum of a
condensate driven by an optical travelling wave. Experimental results are
compared to a numerical solution of the Gross Pitaevskii equation, and analyzed
by a simple two level model and by the more complete band theory, treating the
driving beams as an optical lattice. In this picture, the splitting is a
manifestation of the energy gap between neighboring bands that opens on the
boundary of the Brillouin zone.Comment: 5 pages, 5 figure
Large Magnetic Fields and Motions of OH Masers in W75 N
We report on a second epoch of VLBA observations of the 1665 and 1667 MHz OH
masers in the massive star-forming region W75 N. We find evidence to confirm
the existence of very strong (~40 mG) magnetic fields near source VLA 2. The
masers near VLA 2 are dynamically distinct and include a very bright spot
apparently moving at 50 km/s relative to those around VLA 1. This fast-moving
spot may be an example of a rare class of OH masers seen in outflows in
star-forming regions. Due to the variability of these masers and the rapidity
of their motions, tracking these motions will require multiple observations
over a significantly shorter time baseline than obtained here. Proper motions
of the masers near VLA 1 are more suggestive of streaming along magnetized
shocks rather than Keplerian rotation in a disk. The motions of the easternmost
cluster of masers in W75 N (B) may be tracing slow expansion around an unseen
exciting source.Comment: 7 pages including 4 figures (2 color) & 3 tables, to appear in Ap
Low speed aerodynamic characteristics of an 0.075-scale F-15 airplane model at high angles of attack and sideslip
An 0.075 scale model representative of the F-15 airplane was tested in the Ames 12 foot pressure wind tunnel at a Mach number of 0.16 to determine static longitudinal and lateral directional characteristics at spin attitudes for Reynolds numbers from 1.48 to 16.4 million per meter (0.45 to 5.0 million per foot). Angles of attack ranged from 0 to +90 deg and from -40 deg to -80 deg while angles of sideslip were varied from -20 deg to +30 deg. Data were obtained for nacelle inlet ramp angles of 0 to 11 deg with the left and right stabilators deflected 0, -25 deg, and differentially 5 deg and -5 deg. The normal pointed nose and two alternate nose shapes were also tested along with several configurations of external stores. Analysis of the results indicate that at higher Reynolds numbers there is a slightly greater tendency to spin inverted than at lower Reynolds numbers. Use of a hemispherical nose in place of the normal pointed nose provided an over correction in simulating yawing moment effects at high Reynolds numbers
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