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1,571 results on '"Liu, Yongjie"'

1. Data-Driven Stability Assessment of Power Electronic Converters with Multi-Resolution Dynamic Mode Decomposition

Author

Kong, Rui, Sahoo, Subham, Liu, Yongjie, and Blaabjerg, Frede

Subjects
Electrical Engineering and Systems Science - Signal Processing, Electrical Engineering and Systems Science - Systems and Control
Abstract

Harmonic instability occurs frequently in the power electronic converter system. This paper leverages multi-resolution dynamic mode decomposition (MR-DMD) as a data-driven diagnostic tool for the system stability of power electronic converters, not requiring complex modeling and detailed control information. By combining dynamic mode decomposition (DMD) with the multi-resolution analysis used in wavelet theory, dynamic modes and eigenvalues can be identified at different decomposition levels and time scales with the MR-DMD algorithm, thereby allowing for handling datasets with transient time behaviors, which is not achievable using conventional DMD. Further, the selection criteria for important parameters in MR-DMD are clearly defined through derivation, elucidating the reason for enabling it to extract eigenvalues within different frequency ranges. Finally, the analysis results are verified using the dataset collected from the experimental platform of a low-frequency oscillation scenario in electrified railways featuring a single-phase converter.

Published
2024

2. Flexible and Robust Counterfactual Explanations with Minimal Satisfiable Perturbations

Author

Wang, Yongjie, Qian, Hangwei, Liu, Yongjie, Guo, Wei, and Miao, Chunyan

Subjects
Computer Science - Machine Learning, Computer Science - Artificial Intelligence, Statistics - Methodology
Abstract

Counterfactual explanations (CFEs) exemplify how to minimally modify a feature vector to achieve a different prediction for an instance. CFEs can enhance informational fairness and trustworthiness, and provide suggestions for users who receive adverse predictions. However, recent research has shown that multiple CFEs can be offered for the same instance or instances with slight differences. Multiple CFEs provide flexible choices and cover diverse desiderata for user selection. However, individual fairness and model reliability will be damaged if unstable CFEs with different costs are returned. Existing methods fail to exploit flexibility and address the concerns of non-robustness simultaneously. To address these issues, we propose a conceptually simple yet effective solution named Counterfactual Explanations with Minimal Satisfiable Perturbations (CEMSP). Specifically, CEMSP constrains changing values of abnormal features with the help of their semantically meaningful normal ranges. For efficiency, we model the problem as a Boolean satisfiability problem to modify as few features as possible. Additionally, CEMSP is a general framework and can easily accommodate more practical requirements, e.g., casualty and actionability. Compared to existing methods, we conduct comprehensive experiments on both synthetic and real-world datasets to demonstrate that our method provides more robust explanations while preserving flexibility., Comment: Accepted by CIKM 2023

Published
2023
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4. A Study on Xi’an’s International Image Based on the NOW Corpus

Author

Liu, Yongjie, Chen, Hanliang, Striełkowski, Wadim, Editor-in-Chief, Black, Jessica M., Series Editor, Butterfield, Stephen A., Series Editor, Chang, Chi-Cheng, Series Editor, Cheng, Jiuqing, Series Editor, Dumanig, Francisco Perlas, Series Editor, Al-Mabuk, Radhi, Series Editor, Scheper-Hughes, Nancy, Series Editor, Urban, Mathias, Series Editor, Webb, Stephen, Series Editor, Khan, Intakhab Alam, editor, Yu, Zhonggen, editor, Birkök, Mehmet Cüneyt, editor, and Abu Bakar, Abu Yazid, editor

Published
2024
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5. Reduction of Zn-Bearing Dust Using Biomass Char

Author

Zhao, Jianbo, Liu, Xiaohua, He, Fupeng, Liu, Yongjie, You, Zhixiong, Peng, Zhiwei, editor, Zhang, Mingming, editor, Li, Jian, editor, Li, Bowen, editor, Monteiro, Sergio Neves, editor, Soman, Rajiv, editor, Hwang, Jiann-Yang, editor, Kalay, Yunus Eren, editor, Escobedo-Diaz, Juan P., editor, Carpenter, John S., editor, Brown, Andrew D., editor, and Ikhmayies, Shadia, editor

Published
2024
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7. Synergistic passivation and stepped-dimensional perovskite analogs enable high-efficiency near-infrared light-emitting diodes

Author

Liu, Yongjie, Tao, Chen, Cao, Yu, Chen, Liangyan, Wang, Shuxin, Li, Pei, Wang, Cheng, Liu, Chenwei, Ye, Feihong, Hu, Shengyong, Xiao, Meng, Gao, Zheng, Gui, Pengbing, Yao, Fang, Dong, Kailian, Li, Jiashuai, Hu, Xuzhi, Cong, Hengjiang, Jia, Shuangfeng, Wang, Ti, Wang, Jianbo, Li, Gang, Huang, Wei, Ke, Weijun, Wang, Jianpu, and Fang, Guojia

Subjects
Affordable and Clean Energy
Abstract

Formamidinium lead iodide (FAPbI3) perovskites are promising emitters for near-infrared light-emitting diodes. However, their performance is still limited by defect-assisted nonradiative recombination and band offset-induced carrier aggregation at the interface. Herein, we introduce a couple of cadmium salts with acetate or halide anion into the FAPbI3 perovskite precursors to synergistically passivate the material defects and optimize the device band structure. Particularly, the perovskite analogs, containing zero-dimensional formamidinium cadmium iodide, one-dimensional δ-FAPbI3, two-dimensional FA2FAn-1PbnI3n+1, and three-dimensional α-FAPbI3, can be obtained in one pot and play a pivotal and positive role in energy transfer in the formamidinium iodide-rich lead-based perovskite films. As a result, the near-infrared FAPbI3-based devices deliver a maximum external quantum efficiency of 24.1% together with substantially improved operational stability. Combining our findings on defect passivation and energy transfer, we also achieve near-infrared light communication with device twins of light emitting and unprecedented self-driven detection.

Published
2022

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