385 research outputs found
3-D Motion Capture of an Unmodified Drone with Single-chip Millimeter Wave Radar
Accurate motion capture of aerial robots in 3-D is a key enabler for
autonomous operation in indoor environments such as warehouses or factories, as
well as driving forward research in these areas. The most commonly used
solutions at present are optical motion capture (e.g. VICON) and Ultrawideband
(UWB), but these are costly and cumbersome to deploy, due to their requirement
of multiple cameras/sensors spaced around the tracking area. They also require
the drone to be modified to carry an active or passive marker. In this work, we
present an inexpensive system that can be rapidly installed, based on
single-chip millimeter wave (mmWave) radar. Importantly, the drone does not
need to be modified or equipped with any markers, as we exploit the Doppler
signals from the rotating propellers. Furthermore, 3-D tracking is possible
from a single point, greatly simplifying deployment. We develop a novel deep
neural network and demonstrate decimeter level 3-D tracking at 10Hz, achieving
better performance than classical baselines. Our hope is that this low-cost
system will act to catalyse inexpensive drone research and increased autonomy.Comment: Submitted to The 2021 International Conference on Robotics and
Automation (ICRA 2021
Frugivory and seed dispersal by the yellow-throated marten (Martes flavigula), in a subtropical forest of China
The yellow-throated marten, Martes flavigula, is the only living species of the genus Martes found in subtropical and tropical forests (Harrison et al. 2004). It is distributed throughout central and southern Asia in a wide variety of habitats. Despite its extensive geographical range, the ecology and behaviour of this species has so far received little attention, aside from a study of habitat use (Grassman et al. 2005). Studies on other martens have shown that fruits are an important food resource (e.g. M. martes, Bermejo & Guitian 2000; M. foina, Pandolfi et al. 1996). Thus, they are considered to be important potential seed dispersers (Corlett 1998, Herrera 1989, Willson 1993), as confirmed by recent studies (M. melampus, Otani 2002; M. americana, Hickey et al. 1999; M. foina and M. martes, Schaumann & Heinken 2002). Although no systematic study of the diet of M. flavigula has been conducted (Harrison et al. 2004), it is known to be omnivorous and to consume fruit (Gao & Wang 1987). To date, however, there has been no comprehensive study of frugivory and seed dispersal by M. flavigula (but see Corlett 1998)
AtLoc: Attention Guided Camera Localization
Deep learning has achieved impressive results in camera localization, but
current single-image techniques typically suffer from a lack of robustness,
leading to large outliers. To some extent, this has been tackled by sequential
(multi-images) or geometry constraint approaches, which can learn to reject
dynamic objects and illumination conditions to achieve better performance. In
this work, we show that attention can be used to force the network to focus on
more geometrically robust objects and features, achieving state-of-the-art
performance in common benchmark, even if using only a single image as input.
Extensive experimental evidence is provided through public indoor and outdoor
datasets. Through visualization of the saliency maps, we demonstrate how the
network learns to reject dynamic objects, yielding superior global camera pose
regression performance. The source code is avaliable at
https://github.com/BingCS/AtLoc
Gemini GNIRS near-infrared spectroscopy of 50 quasars at z>~5.7
We report initial results from a large Gemini program to observe z>~5.7
quasars with GNIRS near-IR spectroscopy. Our sample includes 50 quasars with
simultaneous ~0.85-2.5 micron spectra covering the rest-frame ultraviolet and
major broad emission lines from Ly-alpha to MgII. We present spectral
measurements for these quasars and compare to their lower-redshift counterparts
at z=1.5-2.3. We find that when quasar luminosity is matched, there are no
significant differences between the rest-UV spectra of z>~5.7 quasars and the
low-z comparison sample. High-z quasars have similar continuum and emission
line properties and occupy the same region in the black hole mass and
luminosity space as the comparison sample, accreting at an average Eddington
ratio of ~0.3. There is no evidence for super-Eddington accretion or
hypermassive (>10^10 Msun) black holes within our sample. We find a mild excess
of quasars with weak CIV lines relative to the control sample. Our results,
corroborating earlier studies but with better statistics, demonstrate that
these high-z quasars are already mature systems of accreting supermassive black
holes operating with the same physical mechanisms as those at lower redshifts.Comment: replaced with the accepted version (ApJ); improved the fitting
results and replaced all figures and tables (w/ minor changes); conclusions
unchange
Probing the interstellar medium and star formation of the Most Luminous Quasar at z=6.3
We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the
ultraluminous quasar SDSSJ010013.02+280225.8 (hereafter, J0100+2802) at z=6.3,
which hosts the most massive supermassive black hole (SMBH) of 1.24x10^10 Msun
known at z>6. We detect the [C II] 158 m fine structure line and molecular
CO(6-5) line and continuum emission at 353 GHz, 260 GHz, and 3 GHz from this
quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also
marginally detected. The [C II] and CO detections suggest active star formation
and highly excited molecular gas in the quasar host galaxy. The redshift
determined with the [C II] and CO lines shows a velocity offset of ~1000 km/s
from that measured with the quasar Mg II line. The CO (2-1) line luminosity
provides direct constraint on the molecular gas mass which is about
(1.0+/-0.3)x10^10 Msun. We estimate the FIR luminosity to be (3.5+/-0.7)x10^12
Lsun, and the UV-to-FIR spectral energy distribution of J0100+2802 is
consistent with the templates of the local optically luminous quasars. The
derived [C II]-to-FIR luminosity ratio of J0100+2802 is 0.0010+/-0.0002, which
is slightly higher than the values of the most FIR luminous quasars at z~6. We
investigate the constraint on the host galaxy dynamical mass of J0100+2802
based on the [C II] line spectrum. It is likely that this ultraluminous quasar
lies above the local SMBH-galaxy mass relationship, unless we are viewing the
system at a small inclination angle.Comment: 19 pages, 4 figures, published by the Astrophysical Journal, minimal
changes in acknowledgement to match the published versio
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