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4,052 results on '"Li, Si"'

3. MDKB-Bot: A Practical Framework for Multi-Domain Task-Oriented Dialogue System

Author

Lao, Yadi, Liu, Weijie, Gao, Sheng, and Li, Si

Subjects
Information technology, T58.5-58.64
Abstract

One of the major challenges to build a task-oriented dialogue system is that dialogue state transition frequently happens between multiple domains such as booking hotels or restaurants. Recently, the encoderdecoder model based on the end-to-end neural network has become an attractive approach to meet this challenge. However, it usually requires a sufficiently large amount of training data and it is not flexible to handle dialogue state transition. This paper addresses these problems by proposing a simple but practical framework called Multi-Domain KB-BOT (MDKB-BOT), which leverages both neural networks and rule-based strategy in natural language understanding (NLU) and dialogue management (DM). Experiments on the data set of the Chinese Human-Computer Dialogue Technology Evaluation Campaign show that MDKB-BOT achieves competitive performance on several evaluation metrics, including task completion rate and user satisfaction.

Published
2019
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4. Doping induced multiferroicity and quantum anomalous Hall effect in $\alpha$-In$_2$Se$_3$ thin films

Author

Tian, Zhiqiang, Li, Jin-Yang, Ouyang, Tao, Liu, Chao-Fei, Liu, Ziran, Li, Si, Pan, Anlian, and Chen, Mingxing

Subjects
Condensed Matter - Materials Science
Abstract

In flat-band materials, the strong Coulomb interaction between electrons can lead to exotic physical phenomena. Recently, $\alpha$-In$_2$Se$_3$ thin films were found to possess ferroelectricity and flat bands. In this work, using first-principles calculations, we find that for the monolayer, there is a Weyl point at $\Gamma$ in the flat band, where the inclusion of the spin-orbit coupling opens a gap. Shifting the Fermi level into the spin-orbit gap gives rise to nontrivial band topology, which is preserved for the bilayer regardless of the interlayer polarization couplings. We further calculate the Chern number and edge states for both the monolayer and bilayer, for which the results suggest that they become quantum anomalous Hall insulators under appropriate dopings. Moreover, we find that the doping-induced magnetism for In$_2$Se$_3$ bilayer is strongly dependent on the interlayer polarization coupling. Therefore, doping the flat bands in In$_2$Se$_3$ bilayer can also yield multiferroicity, where the magnetism is electrically tunable as the system transforms between different polarization states. Our study thus reveals that multiferroicity and nontrivial band topology can be unified into one material for designing multifunctional electronic devices., Comment: 6 pages, 4 figures

Published
2024
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21. A Constrained NILC method for CMB B mode observations

Author

Zhang, Zirui, Liu, Yang, Li, Si-Yu, Li, Haifeng, and Li, Hong

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Internal Linear Combination (ILC) method is commonly employed to extract the cosmic microwave background (CMB) signal from multi-frequency observation maps. However, the performance of the ILC method tends to degrade when the signal-to-noise ratio (SNR) is relatively low, particularly when measuring the primordial $B$-modes to detect the primordial gravitational waves. To address this issue, an enhanced version of the ILC method, known as constrained ILC, is proposed. This method is designed to be more suitable for situations with low signal-to-noise ratio (SNR) by incorporating additional prior foreground information. In our study, we have modified the constraint Needlet ILC method and successfully improved its performance at low SNR. We illustrate our methods using mock data generated from the combination of WMAP, Planck and a ground-based experiment in the northern hemisphere, and the chosen noise level for the ground-based experiment are very conservative which can be easily achieved in the very near future. The results show that the level of foreground residual can be well controlled. In comparison to the standard NILC method, which introduces a bias to the tensor-to-scalar ratio ($r$) of approximately $0.05$, the constrained NILC method exhibits a significantly reduced bias of only around $5\times10^{-3}$ towards $r$ which is much smaller than the statistical error.

Published
2023
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34. Dark matter search with CMB: a study of foregrounds

Author

Zhang, Zi-Xuan, Wang, Yi-Ming, Cang, Junsong, Zhang, Zirui, Liu, Yang, Li, Si-Yu, Gao, Yu, and Li, Hong

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The energy injected from dark matter annihilation and decay processes potentially raises the ionisation of the intergalactic medium and leaves visible footprints on the anisotropy maps of the cosmic microwave background (CMB). Galactic foregrounds emission in the microwave bands contaminate the CMB measurement and may affect the search for dark matter's signature. In this paper, we construct a full CMB data and foreground simulation based on the design of the next-generation ground-based CMB experiments. The foreground residual after the components separation on maps is fully considered in our data analysis, accounting for various contamination from the emission of synchrotron, thermal dust, free-free and spinning dust. We analyse the corresponding sensitivity on dark matter parameters from the temperature and polarization maps, and we find that the CMB foregrounds leave a non-zero yet controllable impact on the sensitivity. Comparing with statistics-only analysis, the CMB foreground residual leads to a factor of at most 19% weakening on energy-injection constraints, depending on the specific dark matter process and experimental configuration. Strong limits on dark matter annihilation rate and decay lifetime can be expected after foreground subtraction., Comment: 6 figures, 2 tables. The foreground, mask maps and simulated datasets used in this work are available at https://github.com/Junsong-Cang/DM_CMB_Forecast

Published
2023
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