26,772 research outputs found
End-to-end Projector Photometric Compensation
Projector photometric compensation aims to modify a projector input image
such that it can compensate for disturbance from the appearance of projection
surface. In this paper, for the first time, we formulate the compensation
problem as an end-to-end learning problem and propose a convolutional neural
network, named CompenNet, to implicitly learn the complex compensation
function. CompenNet consists of a UNet-like backbone network and an autoencoder
subnet. Such architecture encourages rich multi-level interactions between the
camera-captured projection surface image and the input image, and thus captures
both photometric and environment information of the projection surface. In
addition, the visual details and interaction information are carried to deeper
layers along the multi-level skip convolution layers. The architecture is of
particular importance for the projector compensation task, for which only a
small training dataset is allowed in practice. Another contribution we make is
a novel evaluation benchmark, which is independent of system setup and thus
quantitatively verifiable. Such benchmark is not previously available, to our
best knowledge, due to the fact that conventional evaluation requests the
hardware system to actually project the final results. Our key idea, motivated
from our end-to-end problem formulation, is to use a reasonable surrogate to
avoid such projection process so as to be setup-independent. Our method is
evaluated carefully on the benchmark, and the results show that our end-to-end
learning solution outperforms state-of-the-arts both qualitatively and
quantitatively by a significant margin.Comment: To appear in the 2019 IEEE Conference on Computer Vision and Pattern
Recognition (CVPR). Source code and dataset are available at
https://github.com/BingyaoHuang/compenne
The Variation in Molecular Gas Depletion Time among Nearby Galaxies: What are the Main Parameter Dependencies?
We re-analyze correlations between global molecular gas depletion time (Tdep)
and galaxy parameters including stellar mass, specific star formation rate
(sSFR), stellar mass surface density and concentration index. The analysis is
based on the COLD GASS survey, which includes galaxies with stellar mass in the
range 10^10 - 10^11.5 Msun with molecular gas mass estimates derived from
CO(1-0) line measurements. We improve on previous work by Saintonge et al.
(2011b) by estimating SFRs using the combination of GALEX FUV and WISE 22
micron data and by deriving Tdep within a fixed aperture set by the IRAM beam
size. In our new study we find correlations with much smaller scatter.
Dependences of the Tdep on galaxy structural parameters such as stellar mass
surface density and concentration index are now weak or absent. Differences
with previous work arise because dust extinction correlates strongly with
galaxy structural parameters. We further demonstrate that the 'primary' global
parameter correlation is between Tdep and sSFR; all other remaining
correlations can be shown to be induced by this primary dependence. This
implies that galaxies with high current-to-past-averaged star formation
activity, will drain their molecular gas reservoir sooner. We then analyze
molecular gas depletion times on 1-kpc scales in galactic disks using data from
the HERACLES survey. There is remarkably good agreement between the global Tdep
versus sSFR relation for the COLD GASS galaxies and that derived for 1 kpc
scale grid regions in disks. The strong correlation between Tdep and sSFR
extends continuously over a factor of 10 in Tdep from log(SFR/M*) = -11.5 to
-9, i.e. from nearly quiescent patches of the disk to disk regions with very
strong star formation. This leads to the conclusion that the local molecular
gas depletion time in galactic disks is dependent on the local fraction of
young-to-old stars.Comment: Revised to version published in MNRA
Effects of Atmospheric Absorption of Incoming Radiation on the Radiation Limit of the Troposphere: Reply
In response to a comment on their previous note about the Voigt line profile, here the authors clarify relevant statements and numeric algorithms in the original note
The variation in molecular gas depletion time among nearby galaxies: II the impact of galaxy internal structures
We use a data set of nearby galaxies drawn from the HERACLES, ATLAS3D, and
COLD GASS surveys to study variations in molecular gas depletion time (Tdep) in
galaxy structures such as bulges, grand-design spiral arms, bars and rings.
Molecular gas is traced by CO line emission and star formation rate (SFR) is
derived using the combination of far-ultraviolet and mid-infrared (MIR) data.
The contribution of old stars to MIR emission for the ATLAS3D sample is
corrected using 2MASS K-band images. We apply a two-dimensional image
decomposition algorithm to decompose galaxies into bulges and discs. Spiral
arms, bars and rings are identified in the residual maps, and molecular gas
depletion times are derived on a square grid of 1 kpc^2 size. In previous work,
we showed that Tdep correlates strongly with specific star formation rate
(sSFR). We now find that at a given sSFR, the bulge has shorter Tdep than the
disc. The shift to shorter depletion times is most pronounced in the inner
bulge (R < 0.1Re). Grids from galaxies with bars and rings are similar to those
from galactic bulges in that they have reduced Tdep at a given sSFR. In
contrast, the Tdep versus sSFR relation in the discs of galaxies with spiral
arms is displaced to longer Tdep at fixed sSFR. We then show that the
differences in the Tdep-sSFR relation for bulges, discs, arms, bars and rings
can be linked to variations in "stellar", rather than gas surface density
between different structures. Our best current predictor for Tdep, both
globally and for 1 kpc grids, is given by Tdep=
-0.36log(Sigma_SFR)-0.5log(Sigma_*)+5.87.Comment: 14 pages, 13 figures, revised to version accepted in MNRA
Combating China’s Export Contraction: Fiscal Expansion or Accelerated Industrial Reform?
Initially, the global financial crisis caused a surge of financial inflows to China, raising investment, but this abated in 2008, leaving a substantial contraction in export demand. The government’s key response was to commit to an unprecedented fiscal expansion. Two oftignored consequences are, first that government spending is on non-traded goods and services and so enlarges the consequent real appreciation and, second, that a more inward-looking economy causes firms to face less elastic demand and hence to increase oligopoly rents, further enlarging the real appreciation. Both are important for China because of the contribution of its real-exchange-rate sensitive, low-margin labour-intensive export sector to total employment. An economy-wide analysis is offered, using a model that takes explicit account of oligopoly behaviour. The results suggest that a conventional fiscal expansion would further contract the Chinese economy. On the other hand, notwithstanding the export contraction further industrial reform, emphasising the largely state-owned sectors, would reduce costs and foster growth in both output and modern sector employment.China, financial crisis, fiscal expansion, oligopoly, price caps, privatisation
Energy Efficient Coordinated Beamforming for Multi-cell MISO Systems
In this paper, we investigate the optimal energy efficient coordinated
beamforming in multi-cell multiple-input single-output (MISO) systems with
multiple-antenna base stations (BS) and single-antenna mobile stations
(MS), where each BS sends information to its own intended MS with cooperatively
designed transmit beamforming. We assume single user detection at the MS by
treating the interference as noise. By taking into account a realistic power
model at the BS, we characterize the Pareto boundary of the achievable energy
efficiency (EE) region of the links, where the EE of each link is defined
as the achievable data rate at the MS divided by the total power consumption at
the BS. Since the EE of each link is non-cancave (which is a non-concave
function over an affine function), characterizing this boundary is difficult.
To meet this challenge, we relate this multi-cell MISO system to cognitive
radio (CR) MISO channels by applying the concept of interference temperature
(IT), and accordingly transform the EE boundary characterization problem into a
set of fractional concave programming problems. Then, we apply the fractional
concave programming technique to solve these fractional concave problems, and
correspondingly give a parametrization for the EE boundary in terms of IT
levels. Based on this characterization, we further present a decentralized
algorithm to implement the multi-cell coordinated beamforming, which is shown
by simulations to achieve the EE Pareto boundary.Comment: 6 pages, 2 figures, to be presented in IEEE GLOBECOM 201
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