2,125 research outputs found
SCMA with Low Complexity Symmetric Codebook Design for Visible Light Communication
Sparse code multiple access (SCMA) is attracting significant research
interests currently, which is considered as a promising multiple access
technique for 5G systems. It serves as a good candidate for the future
communication network with massive nodes due to its capability of handling user
overloading. Introducing SCMA to visible light communication (VLC) can provide
another opportunity on design of transmission protocols for the communication
network with massive nodes due to the limited communication range of VLC, which
reduces the interference intensity. However, when applying SCMA in VLC systems,
we need to modify the SCMA codebook to accommodate the real and positive signal
requirement for VLC.We apply multidimensional constellation design methods to
SCMA codebook. To reduce the design complexity, we also propose a symmetric
codebook design. For all the proposed design approaches, the minimum Euclidean
distance aims to be maximized. Our symmetric codebook design can reduce design
and detection complexity simultaneously. Simulation results show that our
design implies fast convergence with respect to the number of iterations, and
outperforms the design that simply modifies the existing approaches to VLC
signal requirements
An iterative formula of smallest singular value of nonsingular matrices
We obtain an iterative formula that converges incrementally to the smallest
singular value. Similarly, we obtain an iterative formula that decreases to
converge to the largest singular value
Doc2EDAG: An End-to-End Document-level Framework for Chinese Financial Event Extraction
Most existing event extraction (EE) methods merely extract event arguments
within the sentence scope. However, such sentence-level EE methods struggle to
handle soaring amounts of documents from emerging applications, such as
finance, legislation, health, etc., where event arguments always scatter across
different sentences, and even multiple such event mentions frequently co-exist
in the same document. To address these challenges, we propose a novel
end-to-end model, Doc2EDAG, which can generate an entity-based directed acyclic
graph to fulfill the document-level EE (DEE) effectively. Moreover, we
reformalize a DEE task with the no-trigger-words design to ease the
document-level event labeling. To demonstrate the effectiveness of Doc2EDAG, we
build a large-scale real-world dataset consisting of Chinese financial
announcements with the challenges mentioned above. Extensive experiments with
comprehensive analyses illustrate the superiority of Doc2EDAG over
state-of-the-art methods. Data and codes can be found at
https://github.com/dolphin-zs/Doc2EDAG.Comment: Accepted by EMNLP 201
Driving positron beam acceleration with coherent transition radiation
Positron acceleration in plasma wakefield faces significant challenges since
the positron beam must be pre-generated and precisely coupled into the
wakefield, and most critically, suffers from defocusing issues. Here we propose
a scheme that utilizes laser-driven electrons to produce, inject and accelerate
positrons in a single set-up. The high-charge electron beam from wakefield
acceleration creates copious electron-positron pairs via the Bethe-Heitler
process, followed by enormous coherent transition radiation due to the
electrons' exiting from the metallic foil. Simulation results show that the
coherent transition radiation field reaches up to 10's GV m-1, which captures
and accelerates the positrons to cut-off energy of 1.5 GeV with energy peak of
500 MeV and energy spread is about 24.3%. An external longitudinal magnetic
field of 30 T is also applied to guide the electrons and positrons during the
acceleration process. This proposed method offers a promising way to obtain GeV
fast positron sources
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A Case Study on the Application of DIY Corpus to Translation Criticism: Exemplified by the Four Renderings of Chinese Essayist Zhu Ziqing's Congcong
One-loop Matching and Running via On-shell Amplitudes
In this work, we put forward a straightforward and simple approach to
construct the low-energy effective field theory (EFT) from a given ultraviolet
(UV) full theory by integrating heavy particles out. By calculating the
on-shell amplitudes, we demonstrate how to directly achieve the one-loop
matching of the UV full theory onto the EFT with the complete set of
independent operators in the physical basis, which are usually obtained by
removing the redundant operators in the Green's basis via the equations of
motion. Furthermore, taking specific examples, we explain how to implement the
on-shell-amplitude approach to derive the one-loop renormalization-group
equations for the Wilson coefficients, and to find out the contributions from
the evanescent operators.Comment: 22 pages, 3 figure
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