87 research outputs found
Image Super-resolution with An Enhanced Group Convolutional Neural Network
CNNs with strong learning abilities are widely chosen to resolve
super-resolution problem. However, CNNs depend on deeper network architectures
to improve performance of image super-resolution, which may increase
computational cost in general. In this paper, we present an enhanced
super-resolution group CNN (ESRGCNN) with a shallow architecture by fully
fusing deep and wide channel features to extract more accurate low-frequency
information in terms of correlations of different channels in single image
super-resolution (SISR). Also, a signal enhancement operation in the ESRGCNN is
useful to inherit more long-distance contextual information for resolving
long-term dependency. An adaptive up-sampling operation is gathered into a CNN
to obtain an image super-resolution model with low-resolution images of
different sizes. Extensive experiments report that our ESRGCNN surpasses the
state-of-the-arts in terms of SISR performance, complexity, execution speed,
image quality evaluation and visual effect in SISR. Code is found at
https://github.com/hellloxiaotian/ESRGCNN
Substitution of Ni for Fe in superconducting FeTeSe depresses the normal-state conductivity but not the magnetic spectral weight
We have performed systematic resistivity and inelastic neutron scattering
measurements on FeNiTeSe samples to study the
impact of Ni substitution on the transport properties and the low-energy (
12 meV) magnetic excitations. It is found that, with increasing Ni doping, both
the conductivity and superconductivity are gradually suppressed; in contrast,
the low-energy magnetic spectral weight changes little. Comparing with the
impact of Co and Cu substitution, we find that the effects on conductivity and
superconductivity for the same degree of substitution grow systematically as
the atomic number of the substituent deviates from that of Fe. The impact of
the substituents as scattering centers appears to be greater than any
contribution to carrier concentration. The fact that low-energy magnetic
spectral weight is not reduced by increased electron scattering indicates that
the existence of antiferromagnetic correlations does not depend on electronic
states close to the Fermi energy.Comment: 6 pages, 5 figure
Kilonovae and Optical Afterglows from Binary Neutron Star Mergers. II. Optimal Search Strategy for Serendipitous Observations and Target-of-opportunity Observations of Gravitational Wave Triggers
In the second work of this series, we explore the optimal search strategy for serendipitous and gravitational-wave-triggered target-of-opportunity (ToO) observations of kilonovae and optical short-duration gamma-ray burst (sGRB) afterglows from binary neutron star (BNS) mergers, assuming that cosmological kilonovae are AT2017gfo-like (but with viewing-angle dependence) and that the properties of afterglows are consistent with those of cosmological sGRB afterglows. A one-day cadence serendipitous search strategy with an exposure time of ∼30 s can always achieve an optimal search strategy of kilonovae and afterglows for various survey projects. We show that the optimal detection rates of the kilonovae (afterglows) are ∼0.3/0.6/1/20 yr−1 (∼50/60/100/800 yr−1) for Zwicky the Transient Facility (ZTF)/Multi-channel Photometric Survey Telescope (Mephisto)/Wide Field Survey Telescope (WFST)/Large Synoptic Survey Telescope (LSST), respectively. A better search strategy for SiTian than the current design is to increase the exposure time. In principle, a fully built SiTian can detect ∼7(2000) yr−1 kilonovae (afterglows). Population properties of electromagnetic (EM) signals detected by serendipitous observations are studied in detail. For ToO observations, we predict that one can detect ∼11 yr−1 BNS gravitational wave (GW) events during the fourth observing run (O4) by considering an exact duty cycle of the third observing run. The median GW sky localization area is expected to be ∼10 deg2 for detectable BNS GW events. For O4, we predict that ZTF/Mephisto/WFST/LSST can detect ∼5/4/3/3 kilonovae (∼1/1/1/1 afterglows) per year, respectively. The GW detection rates, GW population properties, GW sky localizations, and optimistic ToO detection rates of detectable EM counterparts for BNS GW events at the Advanced Plus, LIGO Voyager, and ET&CE eras are detailedly simulated in this paper
Searching for candidates of coalescing binary black holes formed through chemically homogeneous evolution in GWTC-3
The LIGO, Virgo, and KAGRA (LVK) collaboration has announced 90 coalescing
binary black holes (BBHs) with to date, however, the
origin of their formation channels is still an open scientific question. Given
various properties of BBHs (BH component masses and individual spins) inferred
using the default priors by the LVK, independent groups have been trying to
explain the formation of the BBHs with different formation channels. Of all
formation scenarios, the chemically homogeneous evolution (CHE) channel has
stood out with distinguishing features, namely, nearly-equal component masses
and preferentially high individual spins aligned with the orbital angular
momentum. We perform Bayesian inference on the BBH events officially reported
in GWTC-3 with astrophysically-predicted priors representing different
formation channels of the isolated binary evolution (CEE: common-envelope
evolution channel; CHE; SMT: stable mass transfer). Given assumed models, we
report strong evidence for GW190517\_055101 being most likely to have formed
through the CHE channel. Assuming the BBH events in the subsample are all
formed through one of the isolated binary evolution channels, we obtain the
lower limits on the local merger rate density of these channels at (CEE), (CHE), and
(SMT) at credible level.Comment: 13 pages, 4 figures, 1 tabl
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