188 research outputs found
Graphene-based spintronic components
A major challenge of spintronics is in generating, controlling and detecting
spin-polarized current. Manipulation of spin-polarized current, in particular,
is difficult. We demonstrate here, based on calculated transport properties of
graphene nanoribbons, that nearly +-100% spin-polarized current can be
generated in zigzag graphene nanoribbons (ZGNRs) and tuned by a source-drain
voltage in the bipolar spin diode, in addition to magnetic configurations of
the electrodes. This unusual transport property is attributed to the intrinsic
transmission selection rule of the spin subbands near the Fermi level in ZGNRs.
The simultaneous control of spin current by the bias voltage and the magnetic
configurations of the electrodes provides an opportunity to implement a whole
range of spintronics devices. We propose theoretical designs for a complete set
of basic spintronic devices, including bipolar spin diode, transistor and logic
gates, based on ZGNRs.Comment: 14 pages, 4 figure
A GAN-based Tunable Image Compression System
The method of importance map has been widely adopted in DNN-based lossy image
compression to achieve bit allocation according to the importance of image
contents. However, insufficient allocation of bits in non-important regions
often leads to severe distortion at low bpp (bits per pixel), which hampers the
development of efficient content-weighted image compression systems. This paper
rethinks content-based compression by using Generative Adversarial Network
(GAN) to reconstruct the non-important regions. Moreover, multiscale pyramid
decomposition is applied to both the encoder and the discriminator to achieve
global compression of high-resolution images. A tunable compression scheme is
also proposed in this paper to compress an image to any specific compression
ratio without retraining the model. The experimental results show that our
proposed method improves MS-SSIM by more than 10.3% compared to the recently
reported GAN-based method to achieve the same low bpp (0.05) on the Kodak
dataset
The Kagome Antiferromagnet: A Schwinger-Boson Mean-Field Theory Study
The Heisenberg antiferromagnet on the Kagom\'{e} lattice is studied in the
framework of Schwinger-boson mean-field theory. Two solutions with different
symmetries are presented. One solution gives a conventional quantum state with
order for all spin values. Another gives a gapped spin liquid
state for spin and a mixed state with both and
orders for spin . We emphasize that the mixed
state exhibits two sets of peaks in the static spin structure factor. And for
the case of spin , the gap value we obtained is consistent with the
previous numerical calculations by other means. We also discuss the
thermodynamic quantities such as the specific heat and magnetic susceptibility
at low temperatures and show that our result is in a good agreement with the
Mermin-Wagner theorem.Comment: 9 pages, 5 figure
C2F-FWN: Coarse-to-Fine Flow Warping Network for Spatial-Temporal Consistent Motion Transfer
Human video motion transfer (HVMT) aims to synthesize videos that one person
imitates other persons' actions. Although existing GAN-based HVMT methods have
achieved great success, they either fail to preserve appearance details due to
the loss of spatial consistency between synthesized and exemplary images, or
generate incoherent video results due to the lack of temporal consistency among
video frames. In this paper, we propose Coarse-to-Fine Flow Warping Network
(C2F-FWN) for spatial-temporal consistent HVMT. Particularly, C2F-FWN utilizes
coarse-to-fine flow warping and Layout-Constrained Deformable Convolution
(LC-DConv) to improve spatial consistency, and employs Flow Temporal
Consistency (FTC) Loss to enhance temporal consistency. In addition, provided
with multi-source appearance inputs, C2F-FWN can support appearance attribute
editing with great flexibility and efficiency. Besides public datasets, we also
collected a large-scale HVMT dataset named SoloDance for evaluation. Extensive
experiments conducted on our SoloDance dataset and the iPER dataset show that
our approach outperforms state-of-art HVMT methods in terms of both spatial and
temporal consistency. Source code and the SoloDance dataset are available at
https://github.com/wswdx/C2F-FWN.Comment: This work is accepted by AAAI202
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