12,826 research outputs found
High voltage solid-state relay
Hybrid microelectronics relay has characteristics significantly superior to conventional solid state relays. Relay provides 2500 Vdc input to output isolation and operates from high threshold logic signal to switch load of 400 Vdc at 2 mA. Technology should be of interest to manufacturers of discrete components
A Ka-band (32 GHz) beacon link experiment (KABLE) with Mars Observer
A proposal for a Ka-Band (32 GHz) Link Experiment (KABLE) with the Mars Observer mission was submitted to NASA. The experiment will rely on the fourth harmonic of the spacecraft X-band transmitter to generate a 33.6 GHz signal. The experiment will rely also on the Deep Space Network (DSN) receiving station equipped to simultaneously receive X- and Ka-band signals. The experiment will accurately measure the spacecraft-to-Earth telecommunication link performance at Ka-band and X-band (8.4 GHz)
Second Epoch Global VLBI Observations of Compact Radio Sources in the M82 Starburst Galaxy
We have presented the results of a second epoch of global Very Long Baseline
Interferometry observations, taken on 23 February 2001 at a wavelength of 18
cm, of the central kiloparsec of the nearby starburst galaxy Messier 82. These
observations were aimed at studying the structural and flux evolution of some
of the compact radio sources in the central region that have been identified as
supernova remnants. The objects 41.95+575 and 43.31+592 have been studied,
expansion velocities of 2500 +/- 1200 km/s and 7350 +/- 2100 km/s respectively
have been derived. Flux densities of 31.1 +/- 0.3 mJy and 17.4 +/- 0.3 mJy have
been measured for the two objects. These results are consistent with
measurements and predictions from previous epochs.Comment: 5 pages, 3 figures. To be published on the accompanying CD of the
Proceedings of IAU Colloquium 192: Supernova
Dilaton in a Multicritical 3+epsilon-D Parity Violating Field Theory
The multi-critical behaviour of an approximately scale and conformal
invariant quantum field theory, which can be regarded as the deformation of the
critical Gross-Neveu model in 3+epsilon dimensions by a nearly marginal parity
violating operator, is studied using a large expansion. When epsilon is
greater than a number of order 1/N, the deformation is marginally relevant and
it is found to exhibit spontaneous breaking of the approximate scale symmetry
accompanied by the appearance of a light scalar in its spectrum. The scalar
mass is parametrically small, of order epsilon times the fermion mass and it
can be identified with a light dilaton. When the dimension is reduced to 3 the
deformation of the Gross-Neveu model becomes marginally irrelevant, what was a
minimum of the potential becomes a maximum and the theory has a
non-perturbative global instability. There is a metastable perturbative phase
where the scalar does not condense and the fermions are massless separated by
an energy barrier with height of order one (rather than N) from an
energetically favoured phase with a runaway condensate
Rubidium spacecraft atomic timing system Final report
Rubidium 87 atomic time and frequency reference system for manned space fligh
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