11,809 research outputs found
Unruh effect for a Dvali-Gabadadze-Porrati Brane
In braneworld cosmology the brane accelerates in the bulk, and hence it
perceives Unruh radiations in the bulk. We discuss the Unruh effect for a
Dvali-Gabadadze-Porrati (DGP) brane. We find that the Unruh temperature is
proportional to the acceleration of the brane, but chemical potential appears
in the distribution function for massless modes. The Unruh temperature does not
vanish even at the limit , which means the gravitational effect
of the 5th dimension vanishes. The Unruh temperature equals the
temperature when the the density of matter on the brane goes to zero for branch
, no matter what the value of the cross radius and the
spatial curvature of the brane take. And if the state equation of the matter on
the brane satisfies , the Unruh temperature always equals the
geometric temperature of the brane for both the two branches, which is also
independent of the cross radius and the spatial curvature. The Unruh
temperature is always higher than geometric temperature for a dust dominated
brane.Comment: 11 pages, 2 eps figures, the Green function for DGP brane is
correcte
Learning Multimodal Word Representation via Dynamic Fusion Methods
Multimodal models have been proven to outperform text-based models on
learning semantic word representations. Almost all previous multimodal models
typically treat the representations from different modalities equally. However,
it is obvious that information from different modalities contributes
differently to the meaning of words. This motivates us to build a multimodal
model that can dynamically fuse the semantic representations from different
modalities according to different types of words. To that end, we propose three
novel dynamic fusion methods to assign importance weights to each modality, in
which weights are learned under the weak supervision of word association pairs.
The extensive experiments have demonstrated that the proposed methods
outperform strong unimodal baselines and state-of-the-art multimodal models.Comment: To be appear in AAAI-1
Circular Convolution Filter Bank Multicarrier (FBMC) System with Index Modulation
Orthogonal frequency division multiplexing with
index modulation (OFDM-IM), which uses the subcarrier indices
as a source of information, has attracted considerable interest
recently. Motivated by the index modulation (IM) concept, we
build a circular convolution filter bank multicarrier with index
modulation (C-FBMC-IM) system in this paper. The advantages
of the C-FBMC-IM system are investigated by comparing the
interference power with the conventional C-FBMC system. As
some subcarriers carry nothing but zeros, the minimum mean
square error (MMSE) equalization bias power will be smaller
comparing to the conventional C-FBMC system. As a result,
our C-FBMC-IM system outperforms the conventional C-FBMC
system. The simulation results demonstrate that both BER and
spectral efficiency improvement can be achieved when we apply
IM into the C-FBMC system
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