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Magnon corner states in twisted bilayer honeycomb magnets

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arXiv 2022年

作者： Hua, Chun-Bo Xiao, Feiping Liu, Zheng-Rong Sun, Jin-Hua Gao, Jin-Hua Chen, Chui-Zhen Tong, Qingjun Zhou, Bin Xu, Dong-Hui School of Electronic and Information Engineering Hubei University of Science and Technology Xianning437100 China Laboratory of Optoelectronic Information and Intelligent Control Hubei University of Science and Technology Xianning437100 China School of Physics and Electronics Hunan University Changsha410082 China Department of Physics Hubei University Wuhan430062 China Department of Physics Ningbo University Ningbo315211 China School of Physics Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan430074 China Institute for Advanced Study School of Physical Science and Technology Soochow University Suzhou215006 China Department of Physics Chongqing Key Laboratory for Strongly Coupled Physics Chongqing University Chongqing400044 China Center of Quantum Materials and Devices Chongqing University Chongqing400044 China

The study of symmetry-protected topological phases of matter has been extended from fermionic electron systems to various bosonic systems. Bosonic topological magnon phases in magnetic materials have received much attention because of their exotic uncharged topologically protected boundary modes and the potential for dissipationless magnonics and spintronic applications. Here, we establish twisted bilayer honeycomb magnets as a platform for hosting second-order topological magnon insulators (SOTMIs) without fine-tuning. We employ a simple, minimal Heisenberg spin model to describe misaligned bilayer sheets of honeycomb ferromagnetic magnets with a large commensurate twist angle. We found that the higher-order topology in this bilayer system shows a significant dependence on the interlayer exchange coupling. The SOTMI, featuring topologically protected magnon corner states that go beyond the conventional bulk-boundary correspondence, appears for ferromagnetic interlayer couplings, while the twisted bilayer exhibits a nodal phase in the case of antiferromagnetic interlayer coupling. At last, relevance to twisted bilayer CrI3 is also discussed. © 2022, CC BY.

关键词： Chromium compounds

Level attraction and PT symmetry in indirectly coupled microresonators

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Physical Review A 2020年第4期102卷 043527-043527页

作者： Zhao-Hui Peng Chun-Xia Jia Yu-Qing Zhang Ji-Bing Yuan Le-Man Kuang Institute of Modern Physics and Department of Physics College of Physics and Electronic Science Hunan University of Science and Technology Xiangtan 411201 China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China College of Physics and Electronic Engineering and Hunan Provincial Key Laboratory of Intelligent Information Processing and Application Hengyang Normal University Hengyang 421008 China

Benefiting from the tunability of their phase delay and gain, we show the possibility of realizing level attraction, parity-time (PT)-, and anti-PT-symmetric photonic structures with indirectly coupled active and passive microresonators mediated by drop-filter waveguides. We find that level attraction originates from two mechanisms, i.e., exceptional point and resonance, and it may emerge not only for dissipative coupling but also coherent coupling and hybrid coupling after considering the gain and loss of microresonators, which confirms the universality of level attraction in the coupled photonic system. On the other hand, the transition from PT to anti-PT symmetry or vice versa may be realizable by tuning their phase delay and gain; thus the indirectly coupled microresonators may provide an excellent platform for exhibiting the unique features of PT and anti-PT symmetry. Furthermore, we also reveal the intrinsic relationship of the line shape and phase behavior of the reflection spectrum with PT symmetry, anti-PT symmetry, and level attraction.

关键词： Nanophotonics Optics & lasers Quantum optics Optical microcavities Waveguides Quantum theory

Dual Grid Voltage Modulated Direct Power control of Grid-Connected Voltage Source Converter under Unbalanced Network Condition

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Dual Grid Voltage Modulated Direct Power Control of Grid-Con...

2019 IEEE PES Innovative Smart Grid Technologies Asia, ISGT 2019

作者： Gao, Shuning Zhao, Haoran Gui, Yonghao School of Electrical Engineering Shandong University Ji'nan250061 China Key Laboratory of Power System Intelligent Dispatch and Control Ministry of Education Shandong University Ji'nan250061 China Automation and Control Section Department of Electronic Systems Aalborg University Aalborg Denmark

ISBN: (纸本)9781728135205

The Grid voltage Modulated Direct Power control (GVM-DPC) for Voltage Source Converter (VSC) is a recently proposed superior control strategies which features several advantages such as fast power reference tracking, simple structure, no need to use synchronizing techniques, strong robustness and so on. In this paper, an improved Dual Grid Voltage Modulated Direct Power control (D-GVM-DPC) strategies for unbalanced grid voltage condition is proposed and compared with regular voltage oriented dual PI control techniques. The idea of this improvement is to separately control the positive and negative sequence power components based on the original GVM-DPC controller. The simulation results shows that the proposed strategy is superior to the dual current control schemes been used with voltage oriented control strategy. © 2019 IEEE.

关键词： Electric power transmission networks

MyoPS: A Benchmark of Myocardial Pathology Segmentation Combining Three-Sequence Cardiac Magnetic Resonance Images

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arXiv 2022年

作者： Li, Lei Wu, Fuping Wang, Sihan Luo, Xinzhe Martín-Isla, Carlos Zhai, Shuwei Zhang, Jianpeng Liu, Yanfei Zhang, Zhen Ankenbrand, Markus J. Jiang, Haochuan Zhang, Xiaoran Wang, Linhong Arega, Tewodros Weldebirhan Altunok, Elif Zhao, Zhou Li, Feiyan Ma, Jun Yang, Xiaoping Puybareau, Elodie Oksuz, Ilkay Bricq, Stephanie Li, Weisheng Punithakumar, Kumaradevan Tsaftaris, Sotirios A. Schreiber, Laura M. Yang, Mingjing Liu, Guocai Xia, Yong Wang, Guotai Escalera, Sergio Zhuang, Xiahai School of Data Science Fudan University Shanghai China School of Biomedical Engineering Shanghai Jiao Tong University Shanghai China Departament de Matemàtiques & Informàtica Universitat de Barcelona Barcelona Spain Computer Vision Center Universitat Autònoma de Barcelona Spain School of Mechanical and Electrical Engineering University of Electronic Science and Technology of China Chengdu China School of Computer Science and Engineering Northwestern Polytechnical University Xi'An China College of Electrical and Information Engineering Hunan University Changsha China National Engineering Laboratory for Robot Visual Perception and Control Technology Changsha China College of Physics and Information Engineering Fuzhou University Fuzhou China Comprehensive Heart Failure Center Wuerzburg University Hospitals Wuerzburg Germany School of Engineering University of Edinburgh Edinburgh United Kingdom School of Robotics Xi'an Jiaotong-Liverpool University Suzhou China Department of Electrical and Computer Engineering University of California Los Angeles United States Department of Radiology and Diagnostic Imaging University of Alberta Edmonton Canada Chongqing Key Laboratory of Image Cognition Chongqing University of Posts and Telecomm-Unications Chongqing China ImViA Laboratory Université Bourgogne Franche-Comté Dijon France Computer Engineering Department Istanbul Technical University Istanbul Turkey Le Kremlin-Bicêtre France Department of Mathematics Nanjing University of Science and Technology Nanjing China Department of Mathematics Nanjing University Nanjing China

Assessment of myocardial viability is essential in diagnosis and treatment management of patients suffering from myocardial infarction, and classification of pathology on myocardium is the key to this assessment. This work defines a new task of medical image analysis, i.e., to perform myocardial pathology segmentation (MyoPS) combining three-sequence cardiac magnetic resonance (CMR) images, which was first proposed in the MyoPS challenge, in conjunction with MICCAI 2020. The challenge provided 45 paired and pre-aligned CMR images, allowing algorithms to combine the complementary information from the three CMR sequences for pathology segmentation. In this article, we provide details of the challenge, survey the works from fifteen participants and interpret their methods according to five aspects, i.e., preprocessing, data augmentation, learning strategy, model architecture and post-processing. In addition, we analyze the results with respect to different factors, in order to examine the key obstacles and explore potential of solutions, as well as to provide a benchmark for future research. We conclude that while promising results have been reported, the research is still in the early stage, and more in-depth exploration is needed before a successful application to the clinics. Note that MyoPS data and evaluation tool continue to be publicly available upon registration via its homepage (***/zhuangxiahai/0/myops20/). © 2022, CC BY-NC-SA.

关键词： Magnetic resonance imaging

Cooperative Pursuit with Multi-Pursuer and One Faster Free-moving Evader

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arXiv 2020年

作者： Fang, Xu Wang, Chen Xie, Lihua Chen, Jie School of Electrical and Electronic Engineering Nanyang Technological University Singapore639798 Singapore Robotics Institute Carnegie Mellon University PittsburghPA15213 United States School of Electronics and Information Engineering Tongji University Shanghai200092 China Key Laboratory of Intelligent Control and Decision of Complex System Beijing Institute of Technology Beijing100081 China

—This paper addresses a multi-pursuer single-evader pursuit-evasion game where the free-moving evader moves faster than the pursuers. Most of the existing works impose constraints on the faster evader such as limited moving area and moving direction. When the faster evader is allowed to move freely without any constraint, the main issues are how to form an encirclement to trap the evader into the capture domain, how to balance between forming an encirclement and approaching the faster evader, and what conditions make the capture possible. In this paper, a distributed pursuit algorithm is proposed to enable pursuers to form an encirclement and approach the faster evader. An algorithm that balances between forming an encirclement and approaching the faster evader is proposed. Moreover, sufficient capture conditions are derived based on the initial spatial distribution and the speed ratios of the pursuers and the evader. Simulation and experimental results on ground robots validate the effectiveness and practicability of the proposed method. Copyright © 2020, The Authors. All rights reserved.

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A Piecewise-Markovian Lyapunov Approach to Reliable Output Feedback control for Fuzzy-Affine Systems With Time-Delays and Actuator Faults

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IEEE TRANSACTIONS ON CYBERNETICS 2018年第9期48卷 2723-2735页

作者： Wei, Yanling Qiu, Jianbin Shi, Peng Wu, Ligang State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin China School of Electrical and Electronic Engineering University of Adelaide Adelaide SA Australia Research Institute of Intelligent Control and Systems Harbin Institute of Technology Harbin China

This paper addresses the problem of delay-dependent robust and reliable H-infinity static output feedback (SOF) control for a class of uncertain discrete-time Takagi-Sugeno fuzzy-affine (FA) systems with time-varying delay and actuator faults in a singular system framework. The Markov chain is employed to describe the actuator faults behaviors. In particular, by utilizing a system augmentation approach, the conventional closed-loop system is converted into a singular FA system. By constructing a piecewise-Markovian Lyapunov-Krasovskii functional, a new H-infinity performance analysis criterion is then presented, where a novel summation inequality and S-procedure are succeedingly employed. Subsequently, thanks to the special structure of the singular system formulation, the piecewise-affine SOF controller design is proposed via a convex program. Lastly, illustrative examples are given to show the efficacy and less conservatism of the presented approach.

关键词： Piecewise Markovian Lyapunov functional reliable output feedback control time-varying delay T-S fuzzy-affine (FA) systems

Determination of weak squeezed vacuum state through photon statistics measurement

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arXiv 2021年

作者： Zuo, Guanhua Zhang, Yuchi Li, Jing Zhu, Shiyao Guo, Yanqiang Zhang, Tiancai State Key Laboratory of Quantum Qptics and Quantum Optics Devices Collaborative Innovation Center of Extreme Optics Institute of Opto-Electronics Shanxi University Taiyuan030006 China College of Physics and Electronic Engineering Shanxi University Taiyuan030006 China Department of Physics Zhejiang University Hangzhou310027 China Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan030600 China

Weak squeezed vacuum light, especially resonant to the atomic transition, plays an important role in quantum storage and generation of various quantum sources. However, the general homodyne detection (HD) cannot determine weak squeezing due to the low signal to noise ratio and the limited resolution of the HD system. Here we provide an alternative method based on photon statistics measurement to determine the weak squeezing of the squeezed vacuum light generated from an optical parametric oscillator working far below the threshold. The approach is established the relationship between the squeezing parameter and the second-order degree of coherence. The theoretical analysis agrees well with the experiment results. The advantage of this method is that it provides a feasible and reliable experimental measure to determine the weak squeezing with high precision and the measurement is independent on the detection efficiency. This method can be used to measure other quantum features for various quantum states with extremely weak non-classicality. Copyright © 2021, The Authors. All rights reserved.

关键词： Optical parametric oscillators

Compliant net for AUV retrieval using a UAV

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IFAC-PapersOnLine 2018年第29期51卷 431-437页

作者： Ivanovic, Antun Polic, Marsela Salah, Omar Orsag, Matko Bogdan, Stjepan Laboratory for Robotics and Intelligent Control Systems Faculty of Electrical Engineering and Computing University of Zagreb Unska 3 Zagreb10 000 Croatia Mechanical Engineering Department Faculty of Engineering Assiut University Assiut Egypt

This paper addresses the problem of retrieving an autonomous underwater vehicle (AUV) with an unmanned aerial vehicle (UAV). The design of the compliant net that naturally adapts to the payload morphology is proposed as a retrieval tool. We constructed the proposed compliant net and conducted experiments with an underwater vehicle model as payload. Furthermore, mathematical model of a system comprised of the UAV and the payload is presented and a mid-ranging controller is utilized for such a system. We also present simulation results and analyze the stability of the UAV with the cable attached payload. © 2018

关键词： Autonomous underwater vehicles Antennas Unmanned aerial vehicles (UAV) Autonomous underwater vehicles (AUV) Marine systems Mechanical design Retrieval tool Soft robotics Underwater vehicles

Coherently confined single-metal-atom chains in 2D semiconductors

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Nature communications 2025年第1期16卷 4924页

作者： Wen Qin Shasha Guo Zixi Liu Peikun Zhang Chao Zhu Yao Wu Ruixi Qiao Zheng Liu Wanlin Guo Zhuhua Zhang State Key Laboratory of Mechanics and Control for Aerospace Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA. Center for Microscopy and Analysis Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. SEU-FEI Nano-Pico Center Key Lab of MEMS of Ministry of Education School of Electronic Science and Engineering Southeast University Nanjing 210096 China. Department of Materials Science and Engineering National University of Singapore 9 Engineering Drive 1 Singapore 117575 Singapore. State Key Laboratory of Mechanics and Control for Aerospace Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. rxqiao@***. Center for Microscopy and Analysis Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. rxqiao@***. School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Singapore. z.liu@ntu.edu.sg. CINTRA CNRS/NTU/THALES UMI 3288 Research Techno Plaza Singapore 639798 Singapore. z.liu@ntu.edu.sg. State Key Laboratory of Mechanics and Control for Aerospace Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. wlguo@***. State Key Laboratory of Mechanics and Control for Aerospace Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Nanjing 210016 China. chuwazhang@***.

Single-metal-atom chains (SMACs) possess a variety of unique properties and functionalities but suffer from ambient vulnerability due to their delicate one-atom-width structures. While some SMACs can be effectively stabilized by nanochannel confining, it remains a pressing challenge to experimentally realize more versatile atomic chains with sufficient stability and extended length. Here, we propose a computational protocol to identify transition metals capable of forming SMACs along mirror twin boundaries in two-dimensional metal dichalcogenides. Taking MoS as a prototypical example, our thermodynamics and kinetics calculations indicate that Co, Ni, Rh, Pd, and Pt atoms can be enticed by the progressive formation of mirror twin boundaries to yield robust SMACs; whereas other transition metal elements tend to result in either substitutional doping or nanoclusters. These findings are supported by successful experimental synthesis of Co-, Ni-, Pd- and Pt-based SMACs using a chemical vapor co-deposition method, which exhibit high stability due to their covalent bonding with MoS grains. These results lay a solid foundation for investigating exotic transport behaviors within extremely confined channels.

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