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arXiv 2024年

作者： Pope, Simon A. Roth, Diane J. Bansal, Aakash Mousa, Mostafa Rezanejad, Ashkan Forte, Antonio E. Nash, Geoff.R. Singleton, Lawrence Langfeldt, Felix Cheer, Jordan Henthorn, Stephen Hooper, Ian R. Hendry, Euan Powell, Alex W. Souslov, Anton Plum, Eric Sun, Kai de Groot, C.H. Muskens, Otto L. Shields, Joe De Galarreta, Carlota Ruiz Wright, C. David Kocabas, Coskun Ergoktas, M. Said Xiao, Jianling Schulz, Sebastian A. Di Falco, Andrea Krasavin, Alexey V. Zayats, Anatoly V. Galiffi, Emanuele Department of Automatic Control and Systems Engineering The University of Sheffield Amy Johnson Building Portobello Street SheffieldS1 3JD United Kingdom Department of Physics London Centre for Nanotechnology King’s College London Strand WC2R 2LS United Kingdom Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University United Kingdom Department of Engineering King’s College London LondonWC2R 2LS United Kingdom Natural Sciences University of Exeter Harrison Building North Park Road Exeter United Kingdom Institute of Sound & Vibration Research University of Southampton University Road Southampton United Kingdom Department of Electronic and Electrical Engineering University of Sheffield Sheffield United Kingdom Centre for Metamaterial Research and Innovation University of Exeter Stoker Road ExeterEX4 4QL United Kingdom T.C.M. Group Cavendish Laboratory University of Cambridge CambridgeCB3 0HE United Kingdom Optoelectronics Research Centre Centre for Photonic Metamaterials University of Southampton Highfield SouthamptonSO17 1BJ United Kingdom School of Physics and Astronomy University of Southampton Southampton United Kingdom Electronics and Computer Science University of Southampton Southampton United Kingdom Institute of Materials Science of Barcelona Universitat Autònoma de Barcelona Bellaterra Barcelona08193 Spain Department of Materials National Graphene Institute University of Manchester United Kingdom Schoolof Physics and Astronomy University of St Andrews North Haugh Fife St. AndrewsKY16 9SS United Kingdom Department of Electrical and Computer Engineering University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Photonics Initiative Advanced Science Research Centre City University of New York 85 St. Nicholas Terrace New YorkNY10027 United States

Active metamaterials are engineered structures that possess novel properties that can be changed after the point of manufacture. Their novel properties arise predominantly from their physical structure, as opposed to their chemical composition and can be changed through means such as direct energy addition into wave paths, or physically changing/morphing the structure in response to both a user or environmental input. Active metamaterials are currently of wide interest to the physics community and encompass a range of sub-domains in applied physics (e.g. photonic, microwave, acoustic, mechanical, etc.). They possess the potential to provide solutions that are more suitable to specific applications, or which allow novel properties to be produced which cannot be achieved with passive metamaterials, such as time-varying or gain enhancement effects. They have the potential to help solve some of the important current and future problems faced by the advancement of modern society, such as achieving net-zero, sustainability, healthcare and equality goals. Despite their huge potential, the added complexity of their design and operation, compared to passive metamaterials creates challenges to the advancement of the field, particularly beyond theoretical and lab -based experiments. This roadmap brings together experts in all types of active metamaterials and across a wide range of areas of applied physics. The objective is to provide an overview of the current state of the art and the associated current/future challenges, with the hope that the required advances identified create a roadmap for the future advancement and application of this field. Copyright © 2024, The Authors. All rights reserved.

关键词： Microwave acoustics

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Small-scale solar jet formation and their associated waves and instabilities

arXiv

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arXiv 2022年

作者： Skirvin, Samuel Verth, Gary González-Avilés, José Juan Shelyag, Sergiy Sharma, Rahul Guzmán, Francisco S. Ballai, Istvan Scullion, Eamon Silva, Suzana S.A. Fedun, Viktor Center for Mathematical Plasma Astrophysics Mathematics Department KU Leuven Celestijnenlaan 200B bus 2400 LeuvenB-3001 Belgium Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Investigadores por México CONACYT Servicio de Clima Espacial Méxio Laboratorio Nacional de Clima Espacial Instituto de Geofísica Unidad Michoacán Universidad Nacional Autónoma de México Antigua Carretera a Pátzcuaro 8701 Ex-Hacienda de San José de la Huerta Michoacán Morelia58190 Mexico School of Information Technology Deakin University Melbourne3125 Australia Department of Mathematics Physics and Electrical Engineering Northumbria University Newcastle upon TyneNE1 8ST United Kingdom Instituto de Física y Matemáticas Universidad Michoacana de San Nicolás de Hidalgo Edificio C3 Cd. Universitaria Morelia Michoacán 5840 Mexico

Studies on small-scale jets’ formation, propagation, evolution, and role, such as type I and II spicules, mottles, and fibrils in the lower solar atmosphere’s energetic balance, have progressed tremendously thanks to the combination of detailed observations and sophisticated mathematical modelling. This review provides a survey of the current understanding of jets, their formation in the solar lower atmosphere, and their evolution from observational, numerical, and theoretical perspectives. First, we review some results to describe the jet properties, acquired numerically, analytically and through high-spatial and temporal resolution observations. Further on, we discuss the role of hydrodynamic and magnetohydrodynamic instabilities, namely Rayleigh-Taylor and Kelvin-Helmholtz instabilities, in jet evolution and their role in the energy transport through the solar atmosphere in fully and partially ionised plasmas. Finally, we discuss several mechanisms of magnetohydrodynamic wave generation, propagation, and energy transport in the context of small-scale solar jets in detail. This review identifies several gaps in the understanding of small-scale solar jets and some misalignments between the observational studies and knowledge acquired through theoretical studies and numerical modelling. It is to be expected that these gaps will be closed with the advent of high-resolution observational instruments, such as Daniel K. Inouye Solar Telescope, Solar Orbiter, Parker Solar Probe, and Solar CubeSats for Linked Imaging Spectropolarimetry, combined with further theoretical and computational developments. © 2022, CC BY.

关键词： Magnetohydrodynamics

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Modeling and MPPT control of a tidal stream generator 4

Modeling and MPPT control of a tidal stream generator

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4th International Conference on control, Decision and Information Technologies, CoDIT 2017

作者： Ghefiri, Khaoula Bouallègue, Soufiene Haggège, Joseph Ghefiri, Khaoula Garrido, Izaskun Garrido, Aitor J. Laboratory of Research in Automatic Control - LA.R.A BP 37 Le Belvédère Tunis1002 Tunisia University of the Basque Country Department of Automatic Control and Systems Engineering Automatic Control Group - ACG Bilbao48012 Spain

ISBN: (纸本)9781509064656

This paper deals with the design, modeling and control of a Tidal Stream Generator (TSG) system including a tidal turbine, a rotor shaft and a Doubly Fed Induction Generator (DFIG). Below high tidal speed the system is regulated so that for every tidal velocity reaches the maximum power. A rotational speed control based-Maximum Power Point Tracking (MPPT) for a TSG is investigated to provide the suitable rotational speed to the system in order to track the maximum power and thus keeping the pitch angle null. Two study cases were proposed to test the performance of the control strategy. The obtained results show that the proposed control provide satisfactory tracking of the MPPT reference. © 2017 IEEE.

关键词： Tidal stream

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Decentralized LQ-consistent event-triggered control over a shared contention-based network

arXiv

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arXiv 2019年

作者： Hadi Balaghi I., M. Antunes, Duarte J. Mamduhi, Mohammad H. Hirche, Sandra Control Systems Technology Group Department of Mechanical Engineering Eindhoven University of Technology P.O. Box 513 EindhovenNL-5600 MB Netherlands Technical University of Munich Ar-cisstraße 21 MunichD-80290 Germany Department of Automatic Control KTH Royal Institute of Technology StockholmSE-100 44 Sweden

Consider a network of multiple independent stochastic linear systems where a scheduler collocated with the output sensors of each system arbitrates data transmissions to a corresponding remote controller through a shared contention-based communication network. While the systems are independent, their optimal controller design problem may generally become coupled, due to network contention, if the schedulers trigger transmissions based on state-dependent events. In this article we propose a class of probabilistic admissible schedulers for which the optimal controllers with respect to local standard LQG costs have the certainty equivalence property and can still be designed decentrally. Then, two scheduling policies within this class are introduced;a non-event-based and an event-based, where they both have an easily adjustable triggering probability at every time-step. The main contributions of this work are as follows: i) proving that for each system, the control loop with the event-based scheduler and its optimal controller outperforms the control loop with the non-event-based scheduler and its associated optimal controller;ii) showing that for each system, the local optimal state estimator for both scheduling policies follows a linear iteration;i) regulation of triggering probabilities of the schedulers by maximizing a network utility function. Copyright © 2019, The Authors. All rights reserved.

关键词： Linear systems

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Wrist tremor suppression based on repetitive control with multi-muscle electrical stimulation ⁎

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IFAC-PapersOnLine 2019年第29期52卷 31-36页

作者： Zan Zhang Bing Chu Yanhong Liu Haichuan Ren D.H. Owens School of Electrical Engineering Zhengzhou University Zhengzhou China Department of Electronics and Computer Science University of Southampton Southampton SO17 1BJ UK Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street Sheffield S1 3JD UK

Tremor is a rhythmic, alternating swing motion caused by involuntary repetition of muscle contraction and relaxation. Although it does not endanger life, it will make the work and daily life of patients difficult. Functional electrical stimulation (FES) has been shown as a promising technique for tremor suppression. Wrist motion is produced by a group of muscles in a collective and coordinate way. However, existing FES-based design methods mostly aim at one pair of muscles associated with the wrist motion, thus limiting the performance of tremor suppression. Furthermore, the possible high level of stimulation required for a single muscle pair can also accelerate muscle fatigue of the patients. To address these problems, this paper uses multiple muscles FES to suppress tremor by fully considering the properties of wrist motion. This paper develops a wrist musculoskeletal model with Hammerstein structure, identifies its parameters, and proposes repetitive controllers based on frequency modified inverse algorithm to suppress tremor. Experimental results are presented to demonstrate its advantages over single muscle stimulation based tremor suppression.

关键词： Tremor suppression functional electrical stimulation (FES) repetitive control multi-muscle electrical stimulation experimental verification

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Sliding Surface Based Schemes for the Tokamak à Configuration Variable

Sliding Surface Based Schemes for the Tokamak à Configurati...

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2018 World Automation Congress, WAC 2018

作者： Marco, Aitor Garrido, Izaskun Garrido, Aitor J. Coda, Stefano Team, Tcv IDOM Advanced Design Analysis Department Bilbao Spain Automatic Control Group ACG Inst. of Research and Development of Processes-IIDP Bilbao Spain LausanneCH-1015 Switzerland IFP-CNR via R. Cozzi 53 Milan20125 Italy

ISBN: (纸本)9781532377914

Fusion power may be seen as the energy of the future in the sense that it composes a potentially clean, cheap and unlimited power source that would reduce the worldwide dependency on non-renewable energies. Nevertheless, while nowadays the fusion reaction process itself has been achieved, significant net power has not yet been obtained, since the generated plasma needs to remain in particular pressure and temperature conditions. For this purpose, the plasma has to be confined. To do so, one of the solutions is to use a fusion reactor device that creates magnetic fields in a toroidal chamber, called Tokamak reactor. The main issue of Tokamak reactors is the presence of plasma instabilities, which provoke the fusion reaction decay and, in consequence, a reduction in the pulse duration. To maintain this pulse duration as long as possible, the use of robust and fast controllers is mandatory due to the unpredictability and the small time constant of the plasma behavior. In this context, this article focuses on improving the controllability of the plasma current, a relevant control variable, crucial during the plasma heating and confinement processes. In particular, two new robust control schemes based on sliding surfaces, namely, a Sliding Mode controller (SMC) and a Supertwisting controller (STC) are presented and applied to the plasma current control problem. In order to test the validity and goodness of the proposed controllers, their behavior is compared to that of the traditional PID schemes applied in these systems, using the RZIp model for the TCV (Tokamak à Configuration Variable) reactor. The obtained results are very promising, leading to consider these controllers as strong candidates to improve the performance of the PID-based controllers usually employed in this kind of systems. © 2018 TSI Press.

关键词： controllers

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Mobile formation coordination and tracking control for multiple non-holonomic vehicles

arXiv

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arXiv 2019年

作者： Peng, Xiuhui Sun, Zhiyong Guo, Kexin Geng, Zhiyong State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science Peking University Beijing100871 China Department of Automatic Control Lund University Sweden School of Electrical and Electronic Engineering Nanyang Technological University Singapore639798 Singapore

This paper addresses forward motion control for trajectory tracking and mobile formation coordination for a group of non-holonomic vehicles on SE(2). Firstly, by constructing an intermediate attitude variable which involves vehicles position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Secondly, the coordination relationships of relative positions and headings are explored thoroughly for a group of non-holonomic vehicles to maintain a mobile formation with rigid body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments. Copyright © 2019, The Authors. All rights reserved.

关键词： Trees (mathematics)

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Nonlinear control structure design using grammatical evolution and lyapunov equation based optimization 15

Nonlinear control structure design using grammatical evoluti...

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15th International Conference on Informatics in control, Automation and Robotics, ICINCO 2018

作者： Reichensdörfer, Elias Odenthal, Dirk Wollherr, Dirk BMW Group Knorrstr. 147 Munich80788 Germany Department of Electrical and Computer Engineering Depart of Automatic Control Engineering Technical University of Munich Theresienstr. 90 Munich80333 Germany BMW M GmbH Daimlerstr. 19 Garching near Munich85748 Germany Department of Electrical and Computer Engineering Depart of Automatic Control Engineering Technical University of Munich Theresienstr. 90 Munich80333 Germany

ISBN: (纸本)9789897583216

A new method for the automated synthesis of nonlinear control laws for nonlinear control systems using grammatical evolution is presented. The controller structure, its parameterization and a quadratic Lyapunov function are the result of a nonlinear, nonconvex optimization process. Evolutionary algorithms based on grammatical evolution are used to find candidates for the control law. These are evaluated using a fitness function incorporating eigenvalue specifications on the linearized closed loop system and bounds on the control input signals. The guaranteed domain of attraction subject to the closed loop performance and stability specifications is maximized by evaluating the solution of the Lyapunov equation on the nonlinear system. The method is tested on two different control systems that contain different types of nonlinearities. The results show that the proposed approach is capable of outperforming state of the art methods by providing stronger stability guarantees and/or better closed loop performance while making less restrictive assumptions. Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

关键词： Nonlinear equations

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Nonlinear Predictive control Applied to Steam/Water Loop in Large Scale Ships

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IFAC-PapersOnLine 2019年第1期52卷 868-873页

作者： Shiquan Zhao Ricardo Cajo Robin De Keyser Sheng Liu Clara M. Ionescu Faculty of Engineering and Architecture Ghent University Research group on Dynamical Systems and Control Technologiepark 914 B9052 Zwijnaarde Belgium College of Automation Harbin Engineering University China Core Lab EEDT- Energy Efficient Drive Trains Flanders Make Grupo de Investigación en Automatización y Control Industrial Campus Gustavo Galindo Km 30.5 Vía Perimetral P.O. Box 09-01-5863 Guayaquil Ecuador Technical University of Cluj Napoca Department of Automatic Control Memorandumului Street no 28 Cluj Romania

In steam/water loop for large scale ships, there are mainly five sub-loops posing different dynamics in the complete process. When optimization is involved, it is necessary to select different prediction horizons for each loop. In this work, the effect of prediction horizon for Multiple-Input Multiple-Output (MIMO) system is studied. Firstly, Nonlinear Extended Prediction Self-Adaptive controller (NEPSAC) is designed for the steam/water loop system. Secondly, different prediction horizons are simulated within the NEPSAC algorithm. Based on simulation results, we conclude that specific tuning of prediction horizons based on loop’s dynamic outperforms the case when a trade-off is made and a single valued prediction horizon is used for all the loops.

关键词： Nonlinear predictive control Prediction horizon Steam power plant Steam/water loop Multi-Input Multi-Output

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Learning Capsules for Vehicle Logo Recognition

Learning Capsules for Vehicle Logo Recognition

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International Conference on Information Fusion

作者： Ruilong Chen Md Asif Jalal Lyudmila Mihaylova Roger K Moore Department of Automatic Control and Systems Engineering University of Sheffield UK Department of Computer Science University of Sheffield UK

Vehicle logo recognition is an important part of vehicle identification in intelligent transportation systems. State-of-the-art vehicle logo recognition approaches use automatically learned features from Convolutional Neural Networks (CNNs). However, CNNs do not perform well when images are rotated and very noisy. This paper proposes an image recognition framework with a capsule network. A capsule is a group of neurons, whose length can represent the existence probability of an entity or part of an entity. The orientation of a capsule contains information about the instantiation parameters such as positions and orientations. Capsules are learned by a routing process, which is more effective than the pooling process in CNNs. This paper, for the first time, develops a capsule learning framework in the field of intelligent transportation systems. By testing with the largest publicly available vehicle logo dataset, the proposed framework gives a quick solution and achieves the highest accuracy (100%) on this dataset. The learning capsules have been tested with different image changes such as rotation and occlusion. Image degradations including blurring and noise effects are also considered, and the proposed framework has proven to be superior to CNNs.

关键词： Kernel Neurons Routing Biological neural networks Feature extraction Intelligent transportation systems Robustness

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