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Enhanced valley zeeman splitting in fe-doped monolayer mos2

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arXiv 2020年

作者： Li, Qi Zhao, Xiaoxu Deng, Longjiang Shi, Zhongtai Liu, Sheng Wei, Qilin Zhang, Linbo Cheng, Yingchun Zhang, Li Lu, Haipeng Gao, Weibo Huang, Wei Qiu, Cheng-Wei Xiang, Gang Pennycook, Stephen John Xiong, Qihua Loh, Kian Ping Peng, Bo National Engineering Research Center of Electromagnetic Radiation Control Materials School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu611731 China Department of Materials Science and Engineering National University of Singapore 9 Engineering Drive 1 117575 Singapore Department of Chemistry Centre for Advanced 2D Materials Graphene Research Centre National University of Singapore 117549 Singapore Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore Key Laboratory of Flexible Electronics Institute of Advanced Materials Nanjing Tech University Nanjing211816 China College of Physical Science and Technology Sichuan University Chengdu610064 China Department of Electrical and Computer Engineering National University of Singapore 117583 Singapore

The "Zeeman effect" offers unique opportunities for magnetic manipulation of the spin degree of freedom (DOF). Recently, valley Zeeman splitting, referring to the lifting of valley degeneracy, has been demonstrated in two-dimensional transition metal dichalcogenides (TMDs) at liquid helium temperature. However, to realize the practical applications of valley pseudospins, the valley DOF must be controllable by a magnetic field at room temperature, which remains a significant challenge. Magnetic doping in TMDs can enhance the Zeeman splitting, however, to achieve this experimentally is not easy. Here, we report unambiguous magnetic manipulation of valley Zeeman splitting at 300 K (geff = -6.4) and 10 K (geff = -11) in a CVD-grown Fe-doped MoS2 monolayer;the effective Landé geff factor can be tuned to -20.7 by increasing the Fe dopant concentration, which represents an approximately fivefold enhancement as compared to undoped MoS2. Our measurements and calculations reveal that the enhanced splitting and geff factors are due to the Heisenberg exchange interaction of the localized magnetic moments (Fe 3d electrons) with MoS2 through the d-orbital hybridization. Copyright © 2020, The Authors. All rights reserved.

关键词： Landforms

Round-Robin Test of Site VSWR Validation for 18-40 GHz Band in Japan

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Round-Robin Test of Site VSWR Validation for 18-40 GHz Band ...

Asia-Pacific Symposium on electromagnetic Compatibility (APEMC)

作者： Jerdvisanop Chakarothai Katsumi Fujii Noriyuki Mitsuzuka Shinichi Okuyama Toshiki Shimazaki Hidenori Muramatsu Katsunori Miura Masaru Yoshihara Hironari Tanaka Kimihiro Tajima Takeshi Yamanaka Masashi Takabe Electromagnetic Compatibility Laboratory Electromagnetic Standard Research Center Radio Research Institute National Institute of Information and Communications Technology Tokyo Japan Matsudo Test Site Telecom Engineering Center Chiba Japan NEC Platforms Ltd. VCCI Council Tokyo Japan Japan Quality Assurance Organization Tokyo Japan EMC-Engineering Department EMC Division Riken Environmental System Co. Ltd. Saitama Japan Ohtama Calibration Service Co. Ltd. Kanagawa Japan EMC Center Environmental Business Unit Global Business Headquarters NTT Advanced Technology Corporation Tokyo Japan Intertek Japan Tokyo Japan

ISBN: (数字)9784885523472

ISBN: (纸本)9798350349498

The validation of test sites for EMI measurements in a frequency range between 18 and 40GHz is required. There has been no instruction specified in the CISPR standards for the site validation in this frequency range. However, the site VSIVR measurements might be time consuming and costly. It would be beneficial in the aspect of time and cost if the site validation can be omitted for 18 to 40GHz when the test site is already compliant with the CISPR 16-1-4 specification below 18GHz. This report shows the round-robin test results of the site VSWR for 1-6, 6-18, and 18-40 GHz bands done in six test sites in Japan. The results have shown the possibility to omit the site validation when the test site is already compliant with the CISPR $6 \mathrm{~dB}$ limit in the frequency range below 18GHz.

关键词： Uncertainty Power measurement Costs Measurement uncertainty electromagnetic interference electromagnetic compatibility Time measurement

MHD analysis on the physical designs of CFETR and HFRC

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Research Square

Research Square 2021年

作者： Zhu, Ping Li, Li Fang, Yu He, Yuling Wang, Shuo Han, Rui Liu, Yue Wang, Xiaojing Zhang, Yang Zhang, Xiaodong Yu, Qingquan Hu, Liqun Wang, Huihui Sun, Youwen Wei, Lai Tang, Weikang Liu, Tong Wang, Zhengxiong Yan, Xingting Huang, Wenlong Hou, Yawei Ji, Xiaoquan Zeng, Shiyong Abdullah, Zafar Chen, Zhongyong Zeng, Long Li, Haolong Chen, Zhipeng Wang, Zhijiang Rao, Bo Zhang, Ming Ding, Yonghua Pan, Yuan International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States College of Science Donghua University Shanghai201620 China School of Physics Dalian University of Technology Dalian116024 China Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials School of Physics and Telecommunication Engineering South China Normal University Guangzhou510006 China Southwestern Institute of Physics P.O. Box 432 Chengdu610041 China CAS Key Laboratory of Geospace Environment Department of Engineering and Applied Physics University of Science and Technology of China Hefei230026 China CAS Institute of Plasma Physics Hefei Anhui230031 China Max-Planck-Institute for Plasma Physics Garching Germany School of Computer Science and Technology Anhui Engineering Laboratory for Industrial Internet Intelligent Applications and Security Anhui University of Technology Ma’anshan Anhui243002 China College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China

The China Fusion engineering Test Reactor (CFETR) and the Huazhong Field Reversed Configuration (HFRC), currently both under intensive physical and engineering designs in China, are the two major projects representative of the low-density steady-state and high-density pulsed pathways to fusion. One of the primary tasks of the physics designs for both CFETR and HFRC is the assessment and analysis of the magnetohydrodynamic (MHD) stability of the proposed design schemes. Comprehensive efforts on the assessment of MHD stability of CFETR and HFRC baseline scenarios have led to preliminary progresses that may further benefit engineering designs. For CFETR, the ECCD power and current for full stabilization on NTM have been predicted in this work, as well as the corresponding controlled magnetic island width. A thorough investigation on RWM stability for CFETR is performed. For 80% of the steady state operation scenarios, active control methods may be required for RWM stabilization. The process of disruption mitigation with massive neon injection on CFETR is simulated. The time scale of and consequences of plasma disruption on CFETR are estimated, which are found equivalent to ITER. Major MHD instabilities such as NTM and RWM remain challenge to steady state tokamak operation. On this basis, next steps on CFETR MHD study are planned on NTM, RWM, and SPI disruption mitigation. For HFRC, plasma heating due to 2D adiabatic compression has been demonstrated in NIMROD simulations. The tilt and rotational instabilities grow on ideal MHD time scale in single fluid MHD model as shown from NIMROD calculations. Two-fluid MHD calculations using NIMROD find FLR stabilizing effects on both tilt and rotational modes. Energetic-particle stabilization of tilt mode was previously demonstrated in C-2 experiments and NIMROD simulations. With stabilization on major MHD instabilities from two-fluid and energetic particle effects, FRC may promise to be an alternative route to compact magnetic f

关键词： Magnetohydrodynamics

Thyroid ultrasound diagnosis improvement via multi-view self-supervised learning and two-stage pre-training

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arXiv 2024年

作者： Wang, Jian Yang, Xin Jia, Xiaohong Xue, Wufeng Chen, Rusi Chen, Yanlin Zhu, Xiliang Liu, Lian Cao, Yan Zhou, Jianqiao Ni, Dong Gu, Ning Key Laboratory for Bio-Electromagnetic Environment and Advanced Medical Theranostics School of Biomedical Engineering and Informatics Nanjing Medical University Nanjing211166 China National-Regional Key Technology Engineering Laboratory for Medical Ultrasound School of Biomedical Engineering Health Science Center Shenzhen University Shenzhen518073 China Marshall Laboratory of Biomedical Engineering Shenzhen University Shenzhen518073 China Lab Shenzhen University Shenzhen518073 China Department of Ultrasound Ruijin Hospital Shanghai Jiaotong University School of Medicine Shanghai200025 China Shenzhen RayShape Medical Technology Co. Ltd Shenzhen518051 China Cardiovascular Disease Research Center Nanjing Drum Tower Hospital Affiliated Hospital of Medical School Medical School Nanjing University Nanjing210093 China

Thyroid nodule classification and segmentation in ultrasound images are crucial for computer-aided diagnosis;however, they face limitations owing to insufficient labeled data. In this study, we proposed a multi-view contrastive self-supervised method to improve thyroid nodule classification and segmentation performance with limited manual labels. Our method aligns the transverse and longitudinal views of the same nodule, thereby enabling the model to focus more on the nodule area. We designed an adaptive loss function that eliminates the limitations of the paired data. Additionally, we adopted a two-stage pre-training to exploit the pre-training on ImageNet and thyroid ultrasound images. Extensive experiments were conducted on a large-scale dataset collected from multiple centers. The results showed that the proposed method significantly improves nodule classification and segmentation performance with limited manual labels and outperforms state-of-the-art self-supervised methods. The two-stage pre-training also significantly exceeded ImageNet pre-training. Copyright © 2024, The Authors. All rights reserved.

关键词： Supervised learning

MHD analysis on the physical designs of CFETR and HFRC

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arXiv 2021年

作者： Zhu, Ping Li, Li Fang, Yu He, Yuling Wang, Shuo Han, Rui Liu, Yue Wang, Xiaojing Zhang, Yang Zhang, Xiaodong Yu, Qingquan Hu, Liqun Wang, Huihui Sun, Youwen Wei, Lai Tang, Weikang Liu, Tong Wang, Zhengxiong Yan, Xingting Huang, Wenlong Hou, Yawei Ji, Xiaoquan Zeng, Shiyong Abdullah, Zafar Chen, Zhongyong Zeng, Long Li, Haolong Chen, Zhipeng Wang, Zhijiang Rao, Bo Zhang, Ming Ding, Yonghua Pan, Yuan International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States College of Science Donghua University Shanghai201620 China Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education School of Physics Dalian University of Technology Dalian116024 China Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials School of Physics and Telecommunication Engineering South China Normal University Guangzhou510006 China Southwestern Institute of Physics P.O. Box 432 Chengdu610041 China CAS Key Laboratory of Geospace Environment Department of Engineering and Applied Physics University of Science and Technology of China Hefei230026 China CAS Institute of Plasma Physics Anhui Hefei230031 China Max-Planck-Institute for Plasma Physics Garching Germany School of Computer Science and Technology Anhui Engineering Laboratory for Industrial Internet Intelligent Applications and Security Anhui University of Technology Anhui Ma'anshan243002 China College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen518060 China

关键词： Magnetoplasma

Near-field radiative heat transfer between hybrid polaritonic structures

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arXiv 2022年

作者： Iqbal, Naeem Zhang, Sen Wang, Shuai Fang, Zezheng Hu, Yaoyuan Dang, Yongdi Zhang, Minjie Jin, Yi Xu, Jianbin Ju, Binfeng Ma, Yungui State Key Lab of Modern Optical Instrumentation Centre for Optical and Electromagnetic Research College of Optical Science and Engineering International Research Center for Advanced Photonics Zhejiang University China The State Key Lab of Fluid Power Transmission and Control School of Mechanical Engineering Zhejiang University Hangzhou310027 China Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou China Department of Electrical and Electronic Engineering The University of Hong Kong Pokfulam Road Hong Kong

Near-field radiative heat transfer between close objects may exceed the far-field blackbody radiation in orders of magnitude when exploiting polaritonic materials. Great efforts have been made to experimentally measure this fundamental stochastic effect but mostly based on simple materials. In this work, we foster an all-optical method to characterize the heat transfer between less explored plasmon-phonon hybrid polaritonic systems made of graphene-SiC heterostructures. A large heat flux about 26 times of the blackbody radiation limit is obtained over a 150-nm vacuum gap, attributed to the couplings of three different surface modes (plasmon, phonon polaritons and frustrated mode). The interaction of polaritonic modes in the hybrid system is also explored to build a switchable thermophotonic device with nearly unity heat flux tunability. This work paves the way for understanding mode-mediated near-field heat transfer and provides a platform for building thermophotonic or thermo-optoelectronic blocks for various applications. © 2022, CC BY.

关键词： Radiative transfer

Substation Equipment Defect Detection Based on Improved YOLOv9

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Substation Equipment Defect Detection Based on Improved YOLO...

Software engineering and Artificial Intelligence (SEAI), IEEE International Conference on

作者： Yongxin Chen Zhenan Du Ao Li Hengxuan Li Wei Zhang State Grid Hubei Electric Power Research Institute Wuhan Hubei China State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST) Wuhan Hubei China State Grid Hubei Electric Power Co. Ltd Wuhan Hubei China State Grid Xiangyang Electric Power Supply Company Xiangyang Hubei China NR Electric Co. Ltd Nanjing Jiangsu China

ISBN: (数字)9798350374346

ISBN: (纸本)9798350374353

Defect detection of substation equipment plays a vital role in the power system, which contributes to the safe operation of the power system. To accurately detect the substation equipment defects, we propose a detection method based on improved YOLOv9. To extract the key features of small targets in the image of substation equipment, an efficient multi-scale attention mechanism (EMA) based on cross-space learning is introduced at backbone network layer of YOLOv9. In addition, to improve the convergence and accuracy of YOLOv9, the Inner-SIoU bounding box regression loss function is introduced rather than the original CIoU bounding box regression loss function, which makes bounding box regression (BBR) faster and more accurate. And experiments are conducted on a dataset containing seven kinds of substation equipment defects. The experimental results show that the accuracy (P), recall (R), and mean average precision (mAP) of our method are 86.9%, 73.5%, and 77.4%, respectively, which are better than that of the baseline methods.

关键词： Substations Accuracy Attention mechanisms Software algorithms Object detection Feature extraction Artificial intelligence

Temperature-insensitive Nanobore Fiber Bragg Grating

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Temperature-insensitive Nanobore Fiber Bragg Grating

Asia Communications and Photonics Conference and Exhibition (ACP)

作者： Cong Xiong Wei Jiang Caoyuan Wang Ruowei Yu Jun He Xuan Li Kang Ying Haiwen Cai Aiqun Liu Limin Xiao Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing School of Information Science and Technology Advanced Fiber Devices and Systems Group Key Laboratory of Micro and Nano Photonic Structures (MoE) Key Laboratory for Information Science of Electromagnetic Waves (MoE) Fudan University Shanghai China College of Physics and Optoelectronic Engineering Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province Shenzhen University Shenzhen China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai China School of Electrical and Electronic Engineering Nanyang Technological University Singapore Yiwu Research Institute of Fudan University Yiwu China

A fiber Bragg grating based on a novel nanobore fiber is proposed and fabricated by the femtosecond laser direct writing technique and the ultraviolet phase mask exposure technique respectively. The nanobore fiber Bragg grating is temperature-insensitive and has a nanochannel embedded in the fiber core, which can be used for nanofluidic applications.

关键词： Temperature sensors Optical fiber sensors Writing Sensor phenomena and characterization Fiber gratings Optical fiber communication Nanostructures

Simulation of the pre-magnetization technology for transformer on ship power system

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IOP Conference Series: Materials Science and engineering 2019年第4期569卷

作者： Dali Wu Zhongxiang Zheng Xianggen Yin Yikai Wang Biao Xu Wuhan Second Ship Design and Research Institute Wuhan 430064 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST) Wuhan 430074 China

The no-load closing of transformer in the medium-voltage ship power system will cause a large inrush current and threaten the security of the system. This paper aims to provide reference for the pre-magnetization technology of the transformer in medium-voltage ship. Firstly, the basic principles of the inrush current and the series small-capacity transformer based pre-magnetization technology for the transformers are analyzed. Based on the analysis, the typical medium-voltage engineering ship and power generation ship are taken as examples to perform the simulation of the series small-capacity transformer based pre-magnetization scheme, and the result shows that the pre-magnetization technology can suppress the inrush current effectively. Besides, the factors of the switch closing time and the number of generators operating in parallel are considered in the research and their effects of on the inrush current as well as the transient voltage drop are analyzed. Finally, the influence of the pre-magnetization scheme on the differential protection is studied and the operation suggestions are given.

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