7,031 research outputs found
Exploring hypotheses in attitude control fault diagnosis
A system which analyzes telemetry and evaluates hypotheses to explain any anomalies that are observed is described. Results achieved from a sample set of failure cases are presented, followed by a brief discussion of the benefits derived from this approach
Controlling basins of attraction in a neural network-based telemetry monitor
The size of the basins of attraction around fixed points in recurrent neural nets (NNs) can be modified by a training process. Controlling these attractive regions by presenting training data with various amount of noise added to the prototype signal vectors is discussed. Application of this technique to signal processing results in a classification system whose sensitivity can be controlled. This new technique is applied to the classification of temporal sequences in telemetry data
Detecting the Dusty Debris of Terrestrial Planet Formation
We use a multiannulus accretion code to investigate debris disks in the
terrestrial zone, at 0.7-1.3 AU around a 1 solar mass star. Terrestrial planet
formation produces a bright dusty ring of debris with a lifetime of at least 1
Myr. The early phases of terrestrial planet formation are observable with
current facilities; the late stages require more advanced instruments with
adaptive optics.Comment: 11 pages of text, 3 figures, accepted for ApJ Letters, additional
info at http://cfa-www.harvard.edu/~kenyon/pf/terra/td
Grothendieck's constant and local models for noisy entangled quantum states
We relate the nonlocal properties of noisy entangled states to Grothendieck's
constant, a mathematical constant appearing in Banach space theory. For
two-qubit Werner states \rho^W_p=p \proj{\psi^-}+(1-p){\one}/{4}, we show
that there is a local model for projective measurements if and only if , where is Grothendieck's constant of order 3. Known bounds
on prove the existence of this model at least for ,
quite close to the current region of Bell violation, . We
generalize this result to arbitrary quantum states.Comment: 6 pages, 1 figur
Characterizing dw1335-29, a recently discovered dwarf satellite of M83
The number, distribution, and properties of dwarf satellites are crucial
probes of the physics of galaxy formation at low masses and the response of
satellite galaxies to the tidal and gas dynamical effects of their more massive
parent.To make progress, it is necessary to augment and solidify the census of
dwarf satellites of galaxies outside the Local Group. M\"uller et al. (2015)
presented 16 dwarf galaxy candidates near M83, but lacking reliable distances,
it is unclear which candidates are M83 satellites. Using red giant branch stars
from the HST/GHOSTS survey in conjunction with ground-based images from
VLT/VIMOS, we confirm that one of the candidates, dw1335-29-- with a projected
distance of 26 kpc from M83 and a distance modulus of -- is a satellite of M83. We estimate an absolute magnitude
, an ellipticity of , a half light
radius of pc, and [Fe/H] = . Owing to
dw1335-29's somewhat irregular shape and possible young stars, we classify this
galaxy as a dwarf irregular or transition dwarf. This is curious, as with a
projected distance of 26 kpc from M83, dw1335-29 is expected to lack recent
star formation. Further study of M83's dwarf population will reveal if star
formation in its satellites is commonplace (suggesting a lack of a hot gas
envelope for M83 that would quench star formation) or rare (suggesting that
dw1335-29 has a larger M83-centric distance, and is fortuitously projected to
small radii).Comment: 7 pages, 5 figures, accepted for publication in MNRA
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