1,343 research outputs found
Handwritten and Printed Text Separation in Real Document
The aim of the paper is to separate handwritten and printed text from a real
document embedded with noise, graphics including annotations. Relying on
run-length smoothing algorithm (RLSA), the extracted pseudo-lines and
pseudo-words are used as basic blocks for classification. To handle this, a
multi-class support vector machine (SVM) with Gaussian kernel performs a first
labelling of each pseudo-word including the study of local neighbourhood. It
then propagates the context between neighbours so that we can correct possible
labelling errors. Considering running time complexity issue, we propose linear
complexity methods where we use k-NN with constraint. When using a kd-tree, it
is almost linearly proportional to the number of pseudo-words. The performance
of our system is close to 90%, even when very small learning dataset where
samples are basically composed of complex administrative documents.Comment: Machine Vision Applications (2013
Spitzer Observations of Transient, Extended Dust in Two Elliptical Galaxies: New Evidence of Recent Feedback Energy Release in Galactic Cores
Spitzer observations of extended dust in two optically normal elliptical
galaxies provide a new confirmation of buoyant feedback outflow in the hot gas
atmospheres around these galaxies. AGN feedback energy is required to prevent
wholesale cooling and star formation in these group-centered galaxies. In NGC
5044 we observe interstellar (presumably PAH) emission at 8 microns out to
about 5 kpc. Both NGC 5044 and 4636 have extended 70 microns emission from cold
dust exceeding that expected from stellar mass loss. The sputtering lifetime of
this extended dust in the ~1keV interstellar gas, ~10^7 yrs, establishes the
time when the dust first entered the hot gas. Evidently the extended dust
originated in dusty disks or clouds, commonly observed in elliptical galaxy
cores, that were disrupted, heated and buoyantly transported outward. The
surviving central dust in NGC 5044 and 4636 has been disrupted into many small
filaments. It is remarkable that the asymmetrically extended 8 micron emission
in NGC 5044 is spatially coincident with Halpha+[NII] emission from warm gas. A
calculation shows that dust-assisted cooling in buoyant hot gas moving out from
the galactic core can cool within a few kpc in about ~10^7 yrs, explaining the
optical line emission observed. The X-ray images of both galaxies are
disturbed. All timescales for transient activity - restoration of equilibrium
and buoyant transport in the hot gas, dynamics of surviving dust fragments, and
dust sputtering - are consistent with a central release of feedback energy in
both galaxies about 10^7 yrs ago.Comment: 13 pages. Accepted by ApJ; minor typos correcte
The influence of twin boundaries on the Flux Line Lattice structure in YBaCuO: a study by Small Angle Neutron Scattering
The influence of Twin Boundaries (TB) on the Flux Line Lattice(FLL) structure
was investigated by Small Angle Neutron Scattering (SANS). YBaCuO single
crystals possessing different TB densities were studied. The SANS experiments
show that the TB strongly modify the structure of the FLL. The flux lines
meander as soon as the magnetic field makes an angle with the TB direction.
According to the value of this angle but also to the ratio of the flux lines
density over the TB density, one observes that the FLL exhibits two different
unit cells in the plane perpendicular to the magnetic field. One is the
classical hexagonal and anisotropic cell while the other is affected by an
additional deformation induced by the TB. We discuss a possible relation
between this deformation and the increase of the critical current usually
observed in heavily twinned samples.Comment: accepted for publication in Phys Rev
-Poincar\'e invariant quantum field theories with KMS weight
A natural star product for 4-d -Minkowski space is used to
investigate various classes of -Poincar\'e invariant scalar field
theories with quartic interactions whose commutative limit coincides with the
usual theory. -Poincar\'e invariance forces the integral
involved in the actions to be a twisted trace, thus defining a KMS weight for
the noncommutative (C*-)algebra modeling the -Minkowski space. The
associated modular group and Tomita modular operator are characterized. In all
the field theories, the twist generates different planar one-loop contributions
to the 2-point function which are at most UV linearly diverging. Some of these
theories are free of UV/IR mixing. In the others, UV/IR mixing shows up in
non-planar contributions to the 2-point function as a polynomial singularity at
exceptional zero external momenta while staying finite at non-zero external
momenta. These results are discussed together with the possibility for the KMS
weight relative to the quantum space algebra to trigger the appearance of KMS
state on the algebra of observables.Comment: 32 pages, several paragraphs added, published in PR
Détermination des substrats lacustres par hydroacoustique : application au suivit de qualité morphologique
La diversitĂ© des Ă©cosystĂšmes lacustres sâexplique en partie par la variĂ©tĂ© hydromorphologique des lacs ; la nature et la rĂ©partition du substrat qui tapisse leur fond sont des composantes de ce paramĂštre. Câest pour cela que la Directive Cadre sur lâEau impose une description de la nature des sĂ©diments des plans dâeau. Plus gĂ©nĂ©ralement, la rĂ©partition des substrats peut ĂȘtre considĂ©rĂ©e comme un facteur de structuration des espĂšces biologiques quâabrite un lac. Des outils traditionnels comme lâutilisation dâune benne Ă sĂ©diment ou dâune camĂ©ra subaquatique permettent de dĂ©terminer la nature des substrats de maniĂšre trĂšs ponctuelle mais ces techniques atteignent leurs limites lorsque tout un plan dâeau doit ĂȘtre caractĂ©risĂ©. Depuis les annĂ©es 1980 des mĂ©thodes de caractĂ©risation des sĂ©diments utilisant des outils acoustiques qui permettent dâobtenir des informations en continu le long de parcours rĂ©alisĂ©s par un navire ont Ă©tĂ© dĂ©veloppĂ©es et commercialisĂ©es. Pour lâapplication aux Ă©cosystĂšmes lacustres, de part leur mise en oeuvre, les systĂšmes utilisant les Ă©chosondeurs monoâfaisceau paraissent les plus appropriĂ©s. Ces appareils permettent de rĂ©aliser des cartes de la rĂ©partition des substrats Ă lâĂ©chelle du lac. Les informations pertinentes qui permettent de dĂ©crire un Ă©tat biologique potentiel ou de dĂ©finir un Ă©tat initial peuvent ĂȘtre ainsi intĂ©grer dans la mise en place des rĂ©seaux de suivi de la qualitĂ© des milieux. / The lake ecosystem diversity is explained, in part, by the hydromorphological diversity of lakes; nature and repartition of the substrata give information about this parameter. That is the reason why the European Water Framework imposes a substrata nature description of lakes. The substrata repartition could be considered as a factor of the biological structuring presents in lakes. Traditional tools like grab samplers or video cameras enable to determine the substrata nature but they are not appropriate for getting a high resolution description for an entire lake. From the beginning of the 80âs, acoustic devices specialized in seabed classification have been developed and commercialized. For lakebed surveys, systems using single beam sounders seem to be more appropriate; they enable to obtain maps of the lakebed at the whole lake scale. Information which describes a potential biological state can be used for the establishment of a quality monitoring
Les statistiques financiĂšres permettent-elles dâapprĂ©hender les Ă©volutions liĂ©es Ă la mondialisation ?
Les difficultĂ©s dâapprĂ©hension des diverses Ă©volutions liĂ©es Ă la globalisation financiĂšre invitent Ă un examen critique des dispositifs statistiques existants.Mondialisation, statistiques financiĂšres, sociĂ©tĂ©s multinationales, Ă©crans statistiques, hedge funds, marchĂ©s de grĂ© Ă grĂ©, contreparties, rĂ©glementation, centres offshore, obligations dĂ©claratives (reporting requirements), balance des paiements, comptes nationaux financiers.
The Stellar Population Histories of Early-Type Galaxies. II. Controlling Parameters of the Stellar Populations
We analyze single-stellar-population (SSP) equivalent parameters for 50 local
elliptical galaxies as a function of their structural parameters. These
galaxies fill a two-dimensional plane in the four-dimensional space of [Z/H],
log t, log , and [E/Fe]. SSP age and velocity dispersion can be taken
as the two independent parameters that specify a galaxy's location in this
``hyperplane.'' The hyperplane can be decomposed into two sub-relations: (1) a
``Z-plane,'' in which [Z/H] is a linear function of log and log t; and
(2) a relation between [E/Fe] and in which [E/Fe] is larger in
high- galaxies. Cluster and field ellipticals follow the same
hyperplane, but their (,t) distributions within it differ. Nearly all
cluster galaxies are old; the field ellipticals span a large range in SSP age.
The tight Mg-- relations of these ellipticals can be understood as
two-dimensional projections of the metallicity hyperplane showing it edge-on;
the tightness of these relations does not necessarily imply a narrow range of
ages at fixed . The relation between [E/Fe] and is consistent
with a higher effective yield of Type II SNe elements at higher . The
Z-plane is harder to explain and may be a powerful clue to star formation in
elliptical galaxies if it proves to be general. Present data favor a
``frosting'' model in which low apparent SSP ages are produced by adding a
small frosting of younger stars to an older base population. If the frosting
abundances are close to or slightly greater than the base population, simple
two-component models run along lines of constant in the Z-plane, as
required. This favors star formation from well-mixed pre-enriched gas rather
than unmixed low-metallicity gas from an accreted object. (Abridged)Comment: To be published in the June 2000 issue of the Astronomical Journal.
28 pages, 13 figures, uses emulateap
The Surface Brightness Fluctuations and Globular Cluster Populations of M87 and its Companions
Using the surface brightness fluctuations in HST WFPC-2 images, we determine
that M87, NGC 4486B, and NGC 4478 are all at a distance of ~16 Mpc, while NGC
4476 lies in the background at ~21 Mpc. We also examine the globular clusters
of M87 using archived HST fields. We detect the bimodal color distribution, and
find that the amplitude of the red peak relative to the blue peak is greatest
near the center. This feature is in good agreement with the merger model of
elliptical galaxy formation, where some of the clusters originated in
progenitor galaxies while other formed during mergers.Comment: 5 pages, 2 figure
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