14,376 research outputs found
Detachable caster adapter
Detachable caster adapter moves heavy welding tables when fork lift trucks are not practical. A support saddle on the adapter, connected to the caster platform by means of a hinge, fits the leg of the welding table, but can be modified to fit other leg configurations
Optical Turbulence Measurements and Models for Mount John University Observatory
Site measurements were collected at Mount John University Observatory in 2005
and 2007 using a purpose-built scintillation detection and ranging system.
profiling indicates a weak layer located at 12 - 14 km above sea
level and strong low altitude turbulence extending up to 5 km. During calm
weather conditions, an additional layer was detected at 6 - 8 km above sea
level. profiling suggests that tropopause layer velocities are nominally
12 - 30 m/s, and near-ground velocities range between 2 -- 20 m/s, dependent on
weather. Little seasonal variation was detected in either and
profiles. The average coherence length, , was found to be cm for
the full profile at a wavelength of 589 nm. The average isoplanatic angle,
, was arcsec. The mean turbulence altitude,
, was found to be km above sea level. No average in the
Greenwood frequency, , could be established due to the gaps present in the
\vw\s profiles obtained. A modified Hufnagel-Valley model was developed to
describe the profiles at Mount John, which estimates at 6 cm
and at 0.9 arcsec. A series of models were developed, based
on the Greenwood wind model with an additional peak located at low altitudes.
Using the model and the suggested model for moderate ground
wind speeds, is estimated at 79 Hz.Comment: 14 pages; accepted for publication in PAS
Magnetic Trapping of Metastable Calcium Atoms
Metastable calcium atoms, produced in a magneto-optic trap (MOT) operating
within the singlet system, are continuously loaded into a magnetic trap formed
by the magnetic quadrupole field of the MOT. At MOT temperatures of 3 mK and
240 ms loading time we observe 1.1 x 10^8 magnetically trapped 3P2 atoms at
densities of 2.4 x 10^8 cm^-3 and temperatures of 0.61 mK. In a modified scheme
we first load a MOT for metastable atoms at a temperature of 0.18 mK and
subsequently release these atoms into the magnetic trap. In this case 240 ms of
loading yields 2.4 x 10^8 trapped 3P2 atoms at a peak density of 8.7 x 10^10
cm^-3 and a temperature of 0.13 mK. The temperature decrease observed in the
magnetic trap for both loading schemes can be explained only in part by trap
size effects.Comment: 4 figure
Navigation systems for approach and landing of VTOL aircraft
The formulation and implementation of navigation systems used for research investigations in the V/STOLAND avionics system are described. The navigation systems prove position and velocity in a cartestian reference frame aligned with the runway. They use filtering techniques to combine the raw position data from navaids (e.g., TACAN, MLS) with data from onboard inertial sensors. The filtering techniques which use both complementary and Kalman filters, are described. The software for the navigation systems is also described
QED self-energy contribution to highly-excited atomic states
We present numerical values for the self-energy shifts predicted by QED
(Quantum Electrodynamics) for hydrogenlike ions (nuclear charge ) with an electron in an , 4 or 5 level with high angular momentum
(). Applications include predictions of precision transition
energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure
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