11,541 research outputs found
5,5′-Bis[(2,2,2-trifluoroethoxy)methyl]-2,2′-bipyridine
The complete molecule of the title compound, C16H14F6N2O2, is generated by crystallographic inversion symmetry, which results in two short intramolecular C—H⋯N hydrogen-bond contacts per molecule. In the crystal, aromatic π–π stacking [centroid–centroid distance = 3.457 (2) Å] and weak C—H⋯π interactions occur. A short H⋯H [2.32 (3) Å] contact is present
Coordinated Multicasting with Opportunistic User Selection in Multicell Wireless Systems
Physical layer multicasting with opportunistic user selection (OUS) is
examined for multicell multi-antenna wireless systems. By adopting a two-layer
encoding scheme, a rate-adaptive channel code is applied in each fading block
to enable successful decoding by a chosen subset of users (which varies over
different blocks) and an application layer erasure code is employed across
multiple blocks to ensure that every user is able to recover the message after
decoding successfully in a sufficient number of blocks. The transmit signal and
code-rate in each block determine opportunistically the subset of users that
are able to successfully decode and can be chosen to maximize the long-term
multicast efficiency. The employment of OUS not only helps avoid
rate-limitations caused by the user with the worst channel, but also helps
coordinate interference among different cells and multicast groups. In this
work, efficient algorithms are proposed for the design of the transmit
covariance matrices, the physical layer code-rates, and the target user subsets
in each block. In the single group scenario, the system parameters are
determined by maximizing the group-rate, defined as the physical layer
code-rate times the fraction of users that can successfully decode in each
block. In the multi-group scenario, the system parameters are determined by
considering a group-rate balancing optimization problem, which is solved by a
successive convex approximation (SCA) approach. To further reduce the feedback
overhead, we also consider the case where only part of the users feed back
their channel vectors in each block and propose a design based on the balancing
of the expected group-rates. In addition to SCA, a sample average approximation
technique is also introduced to handle the probabilistic terms arising in this
problem. The effectiveness of the proposed schemes is demonstrated by computer
simulations.Comment: Accepted by IEEE Transactions on Signal Processin
Self-Tuned Deep Super Resolution
Deep learning has been successfully applied to image super resolution (SR).
In this paper, we propose a deep joint super resolution (DJSR) model to exploit
both external and self similarities for SR. A Stacked Denoising Convolutional
Auto Encoder (SDCAE) is first pre-trained on external examples with proper data
augmentations. It is then fine-tuned with multi-scale self examples from each
input, where the reliability of self examples is explicitly taken into account.
We also enhance the model performance by sub-model training and selection. The
DJSR model is extensively evaluated and compared with state-of-the-arts, and
show noticeable performance improvements both quantitatively and perceptually
on a wide range of images
Do environmental regulations cause enterprises to exit from market? Quasi-natural experiments based on China’s Cleaner Production Standards
Taking the implementation of Cleaner Production Standards at
the industry level in China as a quasi-natural experiment, the
impact of these standards on enterprises’ exit behavior was
empirically analyzed by using the Difference-in-Differences
method. Results suggested that the implementation of Cleaner
Production Standards reduced the probability of enterprises exiting
the market. A parallel trend test, Propensity Score Matching
(PSM), and the exclusion of other policy factors were then used
to verify the robustness of this finding. The impact mechanism
test showed that implementation of the standards reduced the
probability of enterprises exiting the market through improving
total factor productivity and promoting enterprise product innovation.
The heterogeneity test revealed that, on the one hand, the
implementation of Cleaner Production Standards can reduce the
probability of R&D intensive industries and medium-sized enterprises
exiting the market, and protect innovative and moderately
sized enterprises. On the other hand, the implementation of
Cleaner Production Standards can increase the probability of
state-owned enterprises and small-scale enterprises exiting the
market and optimize the allocation of resources among enterprises.
This paper has important implications for China’s future
approach to environmental policy formulation as well as the optimization
of domestic enterprise structur
Two-component polariton condensate in optical microcavity
We present a scheme for engineering the extended two-component Bose-Hubbard
model using polariton condensate supported by optical microcavity. Compared to
the usual two-component Bose-Hubbard model with only Kerr nonlinearity, our
model includes a nonlinear tunneling term which depends on the number
difference of the particle in the two modes. In the mean field treatment, this
model is an analog to a nonrigid pendulum with a variable pendulum length whose
sign can be also changed. We study the dynamic and ground state properties of
this model and show that there exists a first-order phase transition as the
strength of the nonlinear tunneling rate is varied. Furthermore, we propose a
scheme to obtain the polariton condensate wave function.Comment: 9 pages, 8 figure
Remarks on CLEO New Measurements for Upsilon(1S) Decays to Charmonium Final States and Investigations on Associate Strange Particle Enhancement in Upsilon to J/Psi +X
The recent measurements by CLEO Collaboration for the inclusive J/Psi and
Psi(2S) production in Upsilon(1S) decay and our previous calculation are
analyzed. The J/Psi momentum spectrum and the production ratio of Psi(2S)
versus J/Psi favour Upsilon to J/Psi(Psi(2S)) + ccbar g as the dominant
contribution. We point out that the differences between the experimental data
and our previous results are mainly originated from the setting of the
parameter charm quark mass. We further suggest the associate strange particle
enhancement as a probe for the open charm particles in Upsilon to J/Psi
(Psi(2S)) + ccbar g.Comment: minor corrections during proof-readin
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