6,351 research outputs found
Sparse Vector Distributions and Recovery from Compressed Sensing
It is well known that the performance of sparse vector recovery algorithms
from compressive measurements can depend on the distribution underlying the
non-zero elements of a sparse vector. However, the extent of these effects has
yet to be explored, and formally presented. In this paper, I empirically
investigate this dependence for seven distributions and fifteen recovery
algorithms. The two morals of this work are: 1) any judgement of the recovery
performance of one algorithm over that of another must be prefaced by the
conditions for which this is observed to be true, including sparse vector
distributions, and the criterion for exact recovery; and 2) a recovery
algorithm must be selected carefully based on what distribution one expects to
underlie the sensed sparse signal.Comment: Originally submitted to IEEE Signal Processing Letters in March 2011,
but rejected June 2011. Revised, expanded, and submitted July 2011 to EURASIP
Journal special issue on sparse signal processin
The GTZAN dataset: Its contents, its faults, their effects on evaluation, and its future use
The GTZAN dataset appears in at least 100 published works, and is the
most-used public dataset for evaluation in machine listening research for music
genre recognition (MGR). Our recent work, however, shows GTZAN has several
faults (repetitions, mislabelings, and distortions), which challenge the
interpretability of any result derived using it. In this article, we disprove
the claims that all MGR systems are affected in the same ways by these faults,
and that the performances of MGR systems in GTZAN are still meaningfully
comparable since they all face the same faults. We identify and analyze the
contents of GTZAN, and provide a catalog of its faults. We review how GTZAN has
been used in MGR research, and find few indications that its faults have been
known and considered. Finally, we rigorously study the effects of its faults on
evaluating five different MGR systems. The lesson is not to banish GTZAN, but
to use it with consideration of its contents.Comment: 29 pages, 7 figures, 6 tables, 128 reference
Mrk 1014: An AGN Dominated ULIRG at X-rays
In this paper we report on an XMM-Newton observation of the ultraluminous
infrared QSO Mrk 1014. The X-ray observation reveals a power-law dominated
(photon index of about 2.2) spectrum with a slight excess in the soft energy
range. AGN and starburst emission models fit the soft excess emission equally
well, however, the most plausible explanation is an AGN component as the
starburst model parameter, temperature and luminosity, appear physically
unrealistic. The mean luminosity of Mrk 1014 is about 2 times 10^44 erg s^-1.
We have also observed excess emission at energies greater than 5 keV. This
feature could be attributed to a broadened and redshifted iron complex, but
deeper observations are required to constrain its origin. The light curve shows
small scale variability over the 11 ks observation. There is no evidence of
intrinsic absorption in Mrk 1014. The X-ray observations support the notion of
an AGN dominated central engine. We establish the need for a longer observation
to constrain more precisely the nature of the X-ray components.Comment: 5 pages incl. 3 figures, MNRAS in pres
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