2,292 research outputs found
Standardization of Rational BĂ©zier Surfaces
National audienceThe sufficient and necessary condition for the existence of linear Möbius transformations that can standardize the rational Bézier surfaces is given based on Möbius reparameterization theorem. To obtain the standard form of an arbitrary cubic rational Bézier surface, we then present a quadratic reparameterization algorithm to reparameterize the surface so that all the corner weights of the surface are equal to one. Examples are included to show the performance of the new method.
Studies of Stability and Robustness for Artificial Neural Networks and Boosted Decision Trees
In this paper, we compare the performance, stability and robustness of
Artificial Neural Networks (ANN) and Boosted Decision Trees (BDT) using
MiniBooNE Monte Carlo samples. These methods attempt to classify events given a
number of identification variables. The BDT algorithm has been discussed by us
in previous publications. Testing is done in this paper by smearing and
shifting the input variables of testing samples. Based on these studies, BDT
has better particle identification performance than ANN. The degradation of the
classifications obtained by shifting or smearing variables of testing results
is smaller for BDT than for ANN.Comment: 23 pages, 13 figure
Exploring the total Galactic extinction with SDSS BHB stars
Aims: We used 12,530 photometrically-selected blue horizontal branch (BHB)
stars from the Sloan Digital Sky Survey (SDSS) to estimate the total extinction
of the Milky Way at the high Galactic latitudes, and in each line
of sight. Methods: A Bayesian method was developed to estimate the reddening
values in the given lines of sight. Based on the most likely values of
reddening in multiple colors, we were able to derive the values of and
.
Results: We selected 94 zero-reddened BHB stars from seven globular clusters
as the template. The reddening in the four SDSS colors for the northern
Galactic cap were estimated by comparing the field BHB stars with the template
stars. The accuracy of this estimation is around 0.01\,mag for most lines of
sight. We also obtained to be around 2.40 and map within
an uncertainty of 0.1\,mag. The results, including reddening values in the four
SDSS colors, , and in each line of sight, are released on line. In
this work, we employ an up-to-date parallel technique on GPU card to overcome
time-consuming computations. We plan to release online the C++ CUDA code used
for this analysis.
Conclusions: The extinction map derived from BHB stars is highly consistent
with that from Schlegel, Finkbeiner & Davis(1998). The derived is around
2.40. The contamination probably makes the be larger.Comment: 16 pages, 13 figures, 4 tables, accepted for publication in A&
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