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Regret and Cumulative Constraint Violation Analysis for Distributed Online Constrained Convex Optimization

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arXiv 2021年

作者： Yi, Xinlei Li, Xiuxian Yang, Tao Xie, Lihua Chai, Tianyou Johansson, Karl H. The Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm10044 Sweden The Digital Futures Stockholm10044 Sweden The Department of Control Science and Engineering College of Electronics and Information Engineering The Shanghai Research Institute for Intelligent Autonomous Systems Tongji University Shanghai China The State Key Laboratory of Synthetical Automation for Process Industries Northeastern University Shenyang110819 China School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore

This paper considers the distributed online convex optimization problem with time-varying constraints over a network of agents. This is a sequential decision making problem with two sequences of arbitrarily varying convex loss and constraint functions. At each round, each agent selects a decision from the decision set, and then only a portion of the loss function and a coordinate block of the constraint function at this round are privately revealed to this agent. The goal of the network is to minimize the network-wide loss accumulated over time. Two distributed online algorithms with full-information and bandit feedback are proposed. Both dynamic and static network regret bounds are analyzed for the proposed algorithms, and network cumulative constraint violation is used to measure constraint violation, which excludes the situation that strictly feasible constraints can compensate the effects of violated constraints. In particular, we show that the proposed algorithms achieve O(T max{κ,1-κ}) static network regret and O(T 1-κ/2) network cumulative constraint violation, where T is the time horizon and κ ∈ (0, 1) is a user-defined trade-off parameter. Moreover, if the loss functions are strongly convex, then the static network regret bound can be reduced to O(T κ). Finally, numerical simulations are provided to illustrate the effectiveness of the theoretical results. Copyright © 2021, The Authors. All rights reserved.

关键词： Economic and social effects

Reconstructing Endovascular Catheter Interaction Forces in 3D using Multicore Optical Shape Sensors

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Reconstructing Endovascular Catheter Interaction Forces in 3...

2019 IEEE/RSJ International Conference on intelligent Robots and Systems (IROS)

作者： Christoff M. Heunis Vincenza Belfiore Marilena Vendittelli Sarthak Misra Surgical Robotics Laboratory University of Twente The Netherlands Department of Information Engineering Electronics and Telecommunications and with the Robotics Laboratory at the Department of Computer Control and Management Engineering Sapienza University of Rome Italy

Catheterization instruments are increasingly being improved to accurately diagnose and treat cardiovascular conditions. However, current catheter systems provide limited information about the shape of the catheter and tissue-instrument interaction forces during an intervention. Furthermore, relying on inconsistent feedback of such interaction forces during an intervention may result in tissue injury. This paper presents the first steps to estimate the interaction forces between a catheter and a mock-up arterial environment. We base the proposed method on a Pseudo-Rigid Body approximation of the catheter and integrate three-dimensional shape information provided by Fiber Bragg Grating sensors inside the catheter. The reconstructed forces along the catheter body can be fed back to the surgeon in visual and/or haptic form. In this work, the estimated forces are displayed in real-time in a graphical user interface with the reconstructed catheter shape. Experimental validation demonstrates a root mean square error of 0.03 N and a mean reconstruction error of 0.02 N.

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Switching Method Based Load Frequency control for Power System with Energy-Limited DoS Attacks ⁎

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IFAC-PapersOnLine 2020年第2期53卷 13508-13513页

作者： Xingchen Shang-Guan Li Jin Yong He Chuan-Ke Zhang Lin Jiang Joseph William Spencer Min Wu School of Automation China University of Geosciences Wuhan 430074 China Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan 430074 China Department of Electrical Engineering and Electronics University of Liverpool Liverpool L69 3GJ United Kingdom

A load frequency control (LFC) scheme for modern power systems employs an open communication network to transmit control/measurement signals. The usage of the open communication network in power system makes the LFC scheme more vulnerable to communication network attacks, for example, a denial-of-service (DoS) attack. This attack will prevent a certain amount of transmission of the signals so as to degrade the performance of LFC scheme, or even lead to instability of power system. Therefore, this paper concerns LFC scheme for single-area power system with energy-limited DoS attack based on switching method. Compared with the latest schemes only considering duration of a DoS attacks, the proposed LFC takes fully into account both the duration and attack frequency of the DoS attack. A switching LFC model for a single-area power system is firstly constructed based on the characteristic of periodical sampling and DoS attacks. Then, an exponential stability criterion is developed in terms of the duration and frequency of a DoS attack. Next, a feasible controller of LFC scheme is derived by solving linear matrix inequalities in the criterion. Finally, a detailed design algorithm of LFC scheme is presented for a known DoS attack or an unknown DoS attack. The effectiveness of the proposed LFC scheme is evaluated on a single-area power system under DoS attacks. The proposed LFC scheme is compared with a robust LFC scheme and an event-triggered H ∞ LFC scheme. The obtained contrasting results demonstrate that the proposed LFC scheme can defend DoS attacks with limited energy, and can perform better control effect in the presence of load fluctuations.

关键词： Power system Load frequency control Open communication network Switching system DoS attacks Exponential stability

End to End Multitask Joint Learning Model for Osteoporosis Classification in CT Images

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Computational intelligence and neuroscience 2023年第1期2023卷 3018320页

作者： Kun Zhang Pengcheng Lin Jing Pan Peixia Xu Xuechen Qiu Danny Crookes Liang Hua Lin Wang School of Electrical Engineering Nantong University Nantong Jiangsu 226001 China. Nantong Key Laboratory of Intelligent Control and Intelligent Computing Nantong Jiangsu 226001 China. Nantong Key Laboratory of Intelligent Medicine Innovation and Transformation Nantong Jiangsu 226001 China. Department of Radiology Affiliated Hospital 2 of Nantong University Nantong Jiangsu 226001 China. College of Mechanical Engineering Donghua University Shanghai 201620 China. School of Electronics Electrical Engineering and Computer Science Queen's University Belfast Belfast BT7 1NN UK.

Osteoporosis is a significant global health concern that can be difficult to detect early due to a lack of symptoms. At present, the examination of osteoporosis depends mainly on methods containing dual-energyX-ray, quantitative CT, etc., which are high costs in terms of equipment and human time. Therefore, a more efficient and economical method is urgently needed for diagnosing osteoporosis. With the development of deep learning, automatic diagnosis models for various diseases have been proposed. However, the establishment of these models generally requires images with only lesion areas, and annotating the lesion areas is time-consuming. To address this challenge, we propose a joint learning framework for osteoporosis diagnosis that combines localization, segmentation, and classification to enhance diagnostic accuracy. Our method includes a boundary heat map regression branch for thinning segmentation and a gated convolution module for adjusting context features in the classification module. We also integrate segmentation and classification features and propose a feature fusion module to adjust the weight of different levels of vertebrae. We trained our model on a self-built dataset and achieved an overall accuracy rate of 93.3% for the three label categories (normal, osteopenia, and osteoporosis) in the testing datasets. The area under the curve for the normal category is 0.973; for the osteopenia category, it is 0.965; and for the osteoporosis category, it is 0.985. Our method provides a promising alternative for the diagnosis of osteoporosis at present.

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Robust exponential load frequency control for time delay power system considering wind power ⁎

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IFAC-PapersOnLine 2020年第2期53卷 12536-12541页

作者： Li Jin Xingchen Shang-Guan Yong He Chuan-Ke Zhang Lin Jiang Min Wu School of Automation China University of Geosciences Wuhan 430074 China Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan 430074 China Department of Electrical Engineering and Electronics University of Liverpool Liverpool L69 3GJ United Kingdom

The injection of intermittent wind power reduces the equivalent inertia of power systems, and therefore, the change rate of frequency deviation for the load frequency control (LFC) schemes is increased. LFC schemes employ communication channels to transmit signals, which introduces time delays resulting in badly dynamic performance. This paper presents a delay-dependent approach to obtain the robust load frequency controllers based on decay rate for a multi-area LFC scheme integrated with wind power. An index of decay rate related to settling time is introduced. For a preset delay upper bound, controller gains are optimized by maximizing the decay rate. Also, the controller gains can be designed under the desired decay rate while obtaining the allowable maximum delay margins. Case studies are based on the deregulated multi-area LFC system to verify the robustness of developed controller against inertia reduction. Moreover, the proposed method enables the frequency deviation to be restrained and eliminated within a few seconds.

关键词： Load frequency control wind power communication delay decay rate

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

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

Degradation mechanism of perovskite under high charge carrier density condition

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arXiv 2021年

作者： Li, Guohui Pi, Huihui Wei, Yanfu Zhou, Bolin Gao, Ya Wen, Rong Hao, Yuying Zhang, Han Ong, Beng S. Cui, Yanxia College of Physics and Optoelectronics Key Laboratory of Interface Science and Engineering in Advanced Materials Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education Taiyuan University of Technology Taiyuan030024 China Shenzhen University Shenzhen518060 China Department of Chemistry Research Centre of Excellence for Organic Electronics Institute of Advanced Materials Hong Kong Baptist University Kowloon Tong Hong Kong

Extensive studies have focused on degradation of perovskite at low charge carrier density (16cm-3), but few have surveyed the degradation mechanism at high charge carrier density (∼1018cm-3). Here, we investigate the degradation mechanisms of perovskite under high charge carrier conditions. Unlike the observations in previous works, we find that MAPbI3degradation starts at surface defects and progressing from the surface defects towards neighboring regions under high charge carrier density condition. By using PbI2passivation, the defect-initiated degradation is significantly suppressed and the nanoplatelet degrades in a layer-by-layer way, enabling the MAPbI3laser sustain for 4500 s (2.7×107pulses), which is almost 3 times longer than that of the nanoplatelet laser without passivation. Meanwhile, the PbI2passivated MAPbI3nanoplatelet laser with the nanoplatelet cavity displaying a maximum quality factor up to ∼7800, the highest reported for all MAPbI3nanoplatelet cavities. Furthermore, a high stability MAPbI3nanoplatelet laser that can last for 8500 s (5.1×107pulses) is demonstrated based on a dual passivation strategy, by retarding the defect-initiated degradation and surface-initiated degradation, simultaneously. This work provides in-depth insights for understanding the degradation of perovskite at high charge carrier density. Copyright © 2021, The Authors. All rights reserved.

关键词： Passivation

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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