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262 results on '"Zhang, Yuanfei"'

21. Selective Terminal Functionalization of Linear Alkanes

Author

Bruffaerts, Jeffrey, primary, Kesten, Inbar, additional, Buhnik-Rosenblau, Keren, additional, Cohen, Anthony, additional, Edri, Nurit, additional, Cormier, Morgan, additional, Zhang, Yuanfei, additional, Ho, Guo-Ming, additional, Massad, Itai, additional, Halfon-Verner, Hila, additional, Kashi, Yechezkel, additional, and Marek, Ilan, additional

Published
2023
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22. A Novel Silver Nanoparticles‐Decorated Metal‐Organic Framework with Rapid and Sustained Antimicrobial Activity Against Drug‐Resistant Candida albicans Through Synergistic Chemodynamic and Sonodynamic Therapy

Author

Zhang, Hong, primary, Zhang, Yuanfei, additional, Li, Yiyang, additional, Hu, Min, additional, Rong, Zihan, additional, Meng, Lingjie, additional, Zhang, Xiaofei, additional, Wen, Luan, additional, Liang, Xiumin, additional, Chen, Zhaopeng, additional, and Liu, Chengcheng, additional

Published
2023
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23. Binary Programmable Optical Pulse Repetition-Rate Multiplication Based on Real-Time Fourier Transform

Author

Li, Zijian, Xie, Qijie, Zhang, Yuanfei, Zhang, Honghui, and Shu, Chester

Abstract

We propose and demonstrate a novel scheme to flexibly generate optical pulse trains with programmable repetition rates using newly designed binary modulation coefficients. The required coefficients are devised based on the principle of real-time Fourier transform (RTFT). By applying binary modulation with a Mach-Zehnder intensity modulator on a periodic pulse train prior to temporal Talbot processing, the multiplication factor can be easily manipulated. As a proof-of-concept, we have successfully produced pulse trains of different repetition rates reaching 250 GHz from a 10-GHz input, corresponding to a programmable multiplication factor of up to 25. The measured radio frequency (RF) spectra of the 20-GHz to 50-GHz output pulse trains exhibit higher than 44-dB subharmonic suppression ratio, indicating high-quality multiplied outputs. Our scheme shows resilience to the extinction ratio of the Mach-Zehnder intensity modulator. We also investigate the phase noise and timing jitter evolution of the multiplied optical pulses. Unlike the conventional Talbot processing approach, our programmable scheme shows a reduction of the timing jitter as the multiplication factor increases. The tolerances of our scheme to non-ideal factors such as bias drift and binary coefficient deviation are numerically analyzed. In addition to pulse repetition-rate multiplication, we demonstrate the versatility of our binary modulation approach in programmable generation of pulsed optical waveforms.

Published
2024
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24. A Personalized Recommendation System for English Teaching Resources Based on Learning Behavior Detection

Author

Zhang Yuanfei

Subjects
Article Subject, Computer Networks and Communications, Computer Science Applications
Abstract

When confronted with a plethora of resources, many students struggle to quickly filter out the content that is relevant to them. Because there are many English teaching resources and it is difficult to accurately recommend suitable teaching resources for students. Therefore, in this paper we suggest a personalized recommendation system for English teaching resources, which is founded on learning behavior detection. To begin with, a spatiotemporal convolutional network is introduced to effectively identify students’ online classroom behavior, and a global attention module is added to increase the model’s ability to learn global feature information. Furthermore, the identified characteristics of student behavior are incorporated into the recommendation module. Similarly, the differential evolution (DE) algorithm is implemented to the smoothing factor and kernel function center of a generalized regression neural network (CRNN) for resource recommendation mode, while taking into account the strong dependence of the GRNN training effect on the smoothing factor and the kernel function center. The smoothing factor and offset factor are optimized and solved, and the optimized smoothing factor and offset factor are used to recommend GRNN resources. Experiments show that the approach described in this work first has a high precision (i.e., 90.98%) in behavior recognition, and second, the recommendation performance is superior to both of the comparison algorithms (i.e., 85.23% and 78.33%), resulting in better resource recommendation accuracy. The fundamental goal of this work is to deliver several important guidelines for the informatization and intelligence of the English educational resources and services.

Published
2022

42. Guatemalan Adolescents' Hopes and Dreams

Author

Ashdown, Brien K., primary, Owens, Gillian, additional, DiPhilippo, Angelina, additional, Zhang, Yuanfei, additional, Deku, Alexandra, additional, Draznin-Nagy, Samuel, additional, and Brown, Carrie M., additional

Published
2021
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46. Comprehensive Evaluation on Power Quality of Tidal Current Convertors

Author

Xia Hainan, Wang Xiangnan, Jia Ning, Zhang Yuanfei, and Xue Caixia

Subjects
020401 chemical engineering, 020209 energy, 0202 electrical engineering, electronic engineering, information engineering, Environmental science, Power quality, Ocean Engineering, 02 engineering and technology, 0204 chemical engineering, Oceanography, Tidal current, Marine engineering
Abstract

With the continuous development of testing and evaluation of tidal current convertors, power quality assessment is becoming more and more critical. According to the characteristics of Chinese tidal current power generation and power quality standards, this paper proposes a comprehensive evaluation method of power quality based on K-means clustering and a support vector machine. The fundamental purpose of the method is to automatically select the weights of various indicators in the comprehensive assessment of power quality, by which the influence of subjective factors can be eliminated. In order to achieve the above purpose, K-means clustering is used for automatically classifying the operational data into five different categories. Then, a support vector machine is used to study and estimate the relationship of the operational data and categories. Using the method proposed in the paper, the analysis of operational data of a tidal current power generation shows that calculation results can objectively reflect the power quality of the device, and the influence of subjective factors is eliminated. The method can provide a reference for the testing and evaluation of a large amount of tidal current convertors in the future.

Published
2019

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