21,472 research outputs found
LO-Net: Deep Real-time Lidar Odometry
We present a novel deep convolutional network pipeline, LO-Net, for real-time
lidar odometry estimation. Unlike most existing lidar odometry (LO) estimations
that go through individually designed feature selection, feature matching, and
pose estimation pipeline, LO-Net can be trained in an end-to-end manner. With a
new mask-weighted geometric constraint loss, LO-Net can effectively learn
feature representation for LO estimation, and can implicitly exploit the
sequential dependencies and dynamics in the data. We also design a scan-to-map
module, which uses the geometric and semantic information learned in LO-Net, to
improve the estimation accuracy. Experiments on benchmark datasets demonstrate
that LO-Net outperforms existing learning based approaches and has similar
accuracy with the state-of-the-art geometry-based approach, LOAM
Holographic entanglement of purification for thermofield double states and thermal quench
We explore the properties of holographic entanglement of purification (EoP)
for two disjoint strips in the Schwarzschild-AdS black brane and the Vaidya-AdS
black brane spacetimes. For two given strips on the same boundary of
Schwarzschild-AdS spacetime, there is an upper bound of the separation beyond
which the holographic EoP will always vanish no matter how wide the strips are.
In the case that two strips are in the two boundaries of the spacetime
respectively, we find that the holographic EoP exists only when the strips are
wide enough. If the width is finite, the EoP can be nonzero in a finite time
region. For thermal quench case, we find that the equilibrium time of
holographic EoP is only sensitive to the width of strips, while that of the
holographic mutual information is sensitive not only to the width of strips but
also to their separation.Comment: 23 pages, 12 figures, major correction of section
A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet
The group velocity of light in material around the AGN jet is acquiescently
one (c as a unit), but this is only a hypothesis. Here, we re-derive apparent
superluminal and Doppler formulas for the general case (it is assumed that the
group velocity of light in the uniform and isotropic medium around a jet (a
beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010)
thought that there may be dense clouds around AGN jet base), and show that the
group velocity of light close to one could seriously affect apparent
superluminal phenomena and Doppler effect in the AGN jet (when the viewing
angle and Lorentz factor take some appropriate values).Comment: 4 pages, 2 figures, new version accepted for publication in Journal
of Astrophysics and Astronom
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