15,851 research outputs found
Quantifying and Transferring Contextual Information in Object Detection
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Difference of optical conductivity between one- and two-dimensional doped nickelates
We study the optical conductivity in doped nickelates, and find the dramatic
difference of the spectrum in the gap (\alt4 eV) between one- (1D)
and two-dimensional (2D) nickelates. The difference is shown to be caused by
the dependence of hopping integral on dimensionality. The theoretical results
explain consistently the experimental data in 1D and
2D nickelates, YCaBaNiO and LaSrNiO,
respectively. The relation between the spectrum in the X-ray aborption
experiments and the optical conductivity in LaSrNiO is
discussed.Comment: RevTeX, 4 pages, 4 figure
Dust-to-gas ratio, factor and CO-dark gas in the Galactic anticentre: an observational study
We investigate the correlation between extinction and H~{\sc i} and CO
emission at intermediate and high Galactic latitudes (|b|>10\degr) within the
footprint of the Xuyi Schmidt Telescope Photometric Survey of the Galactic
anticentre (XSTPS-GAC) on small and large scales. In Paper I (Chen et al.
2014), we present a three-dimensional dust extinction map within the footprint
of XSTPS-GAC, covering a sky area of over 6,000\,deg at a spatial angular
resolution of 6\,arcmin. In the current work, the map is combined with data
from gas tracers, including H~{\sc i} data from the Galactic Arecibo L-band
Feed Array H~{\sc i} survey and CO data from the Planck mission, to constrain
the values of dust-to-gas ratio and CO-to-
conversion factor for the entire GAC
footprint excluding the Galactic plane, as well as for selected star-forming
regions (such as the Orion, Taurus and Perseus clouds) and a region of diffuse
gas in the northern Galactic hemisphere. For the whole GAC footprint, we find
\, and \,. We have also
investigated the distribution of "CO-dark" gas (DG) within the footprint of GAC
and found a linear correlation between the DG column density and the -band
extinction: . The mass fraction of DG is found to be toward
the Galactic anticentre, which is respectively about 23 and 124 per cent of the
atomic and CO-traced molecular gas in the same region. This result is
consistent with the theoretical work of Papadopoulos et al. but much larger
than that expected in the cloud models by Wolfire et al.Comment: 11 pages, 7 figures, accepted for publication in MNRA
Cross-Layer Optimization of Fast Video Delivery in Cache-Enabled Relaying Networks
This paper investigates the cross-layer optimization of fast video delivery
and caching for minimization of the overall video delivery time in a two-hop
relaying network. The half-duplex relay nodes are equipped with both a cache
and a buffer which facilitate joint scheduling of fetching and delivery to
exploit the channel diversity for improving the overall delivery performance.
The fast delivery control is formulated as a two-stage functional non-convex
optimization problem. By exploiting the underlying convex and quasi-convex
structures, the problem can be solved exactly and efficiently by the developed
algorithm. Simulation results show that significant caching and buffering gains
can be achieved with the proposed framework, which translates into a reduction
of the overall video delivery time. Besides, a trade-off between caching and
buffering gains is unveiled.Comment: 7 pages, 4 figures; accepted for presentation at IEEE Globecom, San
Diego, CA, Dec. 201
Re-identification by Relative Distance Comparison
Abstract—Matching people across nonoverlapping camera views at different locations and different times, known as person reidentification, is both a hard and important problem for associating behavior of people observed in a large distributed space over a prolonged period of time. Person reidentification is fundamentally challenging because of the large visual appearance changes caused by variations in view angle, lighting, background clutter, and occlusion. To address these challenges, most previous approaches aim to model and extract distinctive and reliable visual features. However, seeking an optimal and robust similarity measure that quantifies a wide range of features against realistic viewing conditions from a distance is still an open and unsolved problem for person reidentification. In this paper, we formulate person reidentification as a relative distance comparison (RDC) learning problem in order to learn the optimal similarity measure between a pair of person images. This approach avoids treating all features indiscriminately and does not assume the existence of some universally distinctive and reliable features. To that end, a novel relative distance comparison model is introduced. The model is formulated to maximize the likelihood of a pair of true matches having a relatively smaller distance than that of a wrong match pair in a soft discriminant manner. Moreover, in order to maintain the tractability of the model in large scale learning, we further develop an ensemble RDC model. Extensive experiments on three publicly available benchmarking datasets are carried out to demonstrate the clear superiority of the proposed RDC models over related popular person reidentification techniques. The results also show that the new RDC models are more robust against visual appearance changes and less susceptible to model overfitting compared to other related existing models. Index Terms—Person reidentification, feature quantification, feature selection, relative distance comparison Ç
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