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arXiv 2024年

作者： Jafarzadeh, S. Schiavo, L.A.C.A. Fedun, V. Solanki, S.K. Stangalini, M. Calchetti, D. Verth, G. Jess, D.B. Grant, S.D.T. Ballai, I. Gafeira, R. Keys, P.H. Fleck, B. Morton, R.J. Browning, P.K. Silva, S.S.A. Appourchaux, T. Gandorfer, A. Gizon, L. Hirzberger, J. Kahil, F. Suárez, D. Orozco Schou, J. Strecker, H. del Toro Iniesta, J.C. Valori, G. Volkmer, R. Woch, J. Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany School of Physics & Astronomy The University of Manchester Oxford Road ManchesterM13 9PL United Kingdom Department of Mathematics Physics and Electrical Engineering Northumbria University Newcastle upon TyneNE1 8ST United Kingdom Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom ASI Italian Space Agency Via del Politecnico snc RomeI-00133 Italy Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast BelfastBT7 1NN United Kingdom Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States Instituto de Astrofísica e Ciências do Espaço Department of Physics University of Coimbra Coimbra3040-004 Portugal ESA Science and Operations Department c/o NASA Goddard Space Flight Center GreenbeltMD20771 United States Univ. Paris-Sud Institut d’Astrophysique Spatiale UMR 8617 CNRS Bâtiment 121 Orsay91405 Cedex France Apartado de Correos 3004 GranadaE-18080 Spain Leibniz-Institut für Sonnenphysik Schöneckstr. 6 FreiburgD-79104 Germany Institut für Astrophysik und Geophysik Georg-August-Universität Göttingen Friedrich-Hund-Platz 1 Göttingen37077 Germany

Solar pores are intense concentrations of magnetic flux that emerge through the Sun’s photosphere. When compared to sunspots, they are much smaller in diameter and hence can be impacted and buffeted by neighbouring granular activity to generate significant magnetohydrodynamic (MHD) wave energy flux within their confines. However, observations of solar pores from ground-based telescope facilities may struggle to capture subtle motions synonymous with higher-order MHD wave signatures due to seeing effects produced in the Earth’s atmosphere. Hence, we have exploited timely seeing-free and high-quality observations of four small magnetic pores from the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (PHI) on board the Solar Orbiter spacecraft, during its first close perihelion passage in March 2022 (at a distance of 0.5 au from the Sun). Through acquisition of data under stable observing conditions, we have been able to measure the area fluctuations and horizontal displacements of the solar pores. Cross correlations between perturbations in intensity, area, line-of-sight velocity, and magnetic fields, coupled with the first-time application of novel Proper Orthogonal Decomposition (POD) techniques on the boundary oscillations, provide a comprehensive diagnosis of the embedded MHD waves as sausage and kink modes. Additionally, the previously elusive m = 2 fluting mode is identified in the most magnetically isolated of the four pores. An important consideration lies in how the identified wave modes contribute towards the transfer of energy into the upper solar atmosphere. We find that the four pores examined have approximately 56%, 72%, 52%, and 34% of their total wave energy associated with the identified sausage modes, and around 23%, 17%, 39%, and 49% to their kink modes, respectively, while the first pore also has around an 11% contribution linked to the fluting mode. This study marks the first-time identification of concurrent sausage, kin

关键词： Magnetohydrodynamics

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Variable speed control in wells turbine-based oscillating water column devices: optimum rotational speed

Variable speed control in wells turbine-based oscillating wa...

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2017年第六届电力科学与工程国际会议

作者： J Lekube A J Garrido I Garrido Automatic Control Group (ACG). Institute of Research and Development of Processes (IIDP). Department of Automatic Control and Systems Engineering Faculty of Engineering of Bilbao University of the Basque Country (UPV/EHU)

The effects of climate change and global warming reveal the need to find alternative sources of clean energy. In this sense, wave energy power plants, and in particular Oscillating Water Column(OWC) devices, offer a huge potential of energy harnessing. Nevertheless, the conversion systems have not reached a commercially mature stage yet so as to compete with conventional power plants. At this point, the use of new control methods over the existing technology arises as a doable way to improve the efficiency of the system. Due to the nonuniform response that the turbine shows to the rotational speed variation, the speed control of the turbo-generator may offer a feasible solution for efficiency improvement during the energy conversion. In this context, a novel speed control approach for OWC systems is presented in this paper, demonstrating its goodness and affording promising results when particularized to the Mutriku's wave power plant.

关键词： Variable speed control in wells turbine-based oscillating water column devices optimum rotational speed

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The 2024 Active Metamaterials Roadmap

arXiv

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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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Defect engineering approaches for metal oxide semiconductor-based chemiresistive gas sensing

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Coordination Chemistry Reviews 2025年 541卷

作者： Amit Kumar Julaiba Tahsina Mazumder Kenza Joyen Frédéric Favier Ali Mirzaei Jin-Young Kim Monika Kwoka Mikhael Bechelany Ravindra Kumar Jha Mahesh Kumar Hyoun Woo Kim Sang Sub Kim Department of Electrical Engineering Indian Institute of Technology Jodhpur Jodhpur 342030 India Department of Electronics Assam Skill University Mangaldai Assam 784125 India European Institut of Membranes (IEM) – UMR 5635 University of Montpellier ENSCM CNRS 34090 Montpellier France Institut Charles Gerhardt Montpellier (ICGM) – UMR 5253 University of Montpellier ENSCM CNRS 34090 Montpellier France Department of Materials Science and Engineering Shiraz University of Technology Shiraz 715557-13876 Islamic Republic of Iran Customized manufacturing R&D department Korea Institute of Industrial Technology Gyeonggi-do 15014 South Korea Department of Cybernetics Nanotechnology and Data Processing Faculty of Automatic Control Electronics and Computer Science Silesian University of Technology Akademicka 16 44-100 Gliwice Poland Functional Materials Group Gulf University for Science and Technology (GUST) Mubarak Al-Abdullah 32093 Kuwait Department of Electronics and Electrical Engineering & Centre for Intelligent Cyber-Physical Systems Indian Institute of Technology Guwahati Guwahati 781039 India Division of Materials Science and Engineering Hanyang University Seoul 04763 South Korea Department of Materials Science and Engineering Inha University Incheon 22212 South Korea

Defect engineering in metal oxides presents a promising approach for tailoring material properties. This strategy enhances gas sorption, catalysis, and control over key physical characteristics such as bandgap, magnetic behavior, and electrical conductivity. Despite its potential, the role of defect engineering in advancing metal oxide semiconductor (MOS) gas-sensing performance remains underexplored. This review introduces defect engineering strategies, emphasizing their applications in gas sensing. Gas sensors play a vital role in environmental monitoring, industrial safety, healthcare, and in improving energy efficiency. The demand for advanced gas sensors has never been more critical, given the need for real-time, accurate, and cost-effective detection of pollutant gases. MOS-based gas sensors are widely used in air quality monitoring, industrial safety, and health diagnostics. Vacancies and defect architectures in MOS have been widely studied for their role in sensing performance, as they fundamentally influence sensor efficiency. The effectiveness of MOS sensors largely depends on the type and concentration of defects. This review introduces vacancies and defects in MOS, followed by an in-depth discussion of defect types, factors influencing defect formation, and their role in charge transport. Additionally, it examines the correlation between elemental chemical properties and defect chemistry. Special attention is given to the defect chemistry of metal oxides, including TiO 2 , ZnO, Co 3 O 4 , ZrO 2 , WO 3 , and CeO 2 . It concludes with an examination of surface engineering methods for defect control to improve gas-sensing capabilities.

关键词： Chemiresistive gas sensing Defect engineering Metal-oxide semiconductor

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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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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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Online learning with stability guarantees: A memory-based real-time model predictive controller∗

arXiv

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arXiv 2018年

作者： Schwenkel, Lukas Gharbi, Meriem Trimpe, Sebastian Ebenbauer, Christian Institute for Systems Theory and Automatic Control University of Stuttgart Germany Institute for Data Science in Mechanical Engineering RWTH Aachen University Germany Intelligent Control Systems Group Max Planck Institute for Intelligent Systems Stuttgart Germany

We propose and analyze a real-time model predictive control (MPC) scheme that utilizes stored data to improve its performance by learning the value function online with stability guarantees. For linear and nonlinear systems, a learning method is presented that makes use of basic analytic properties of the cost function and is proven to learn the MPC control law and the value function on the limit set of the closed-loop state trajectory. The main idea is to generate a smart warm start based on historical data that improves future data points and thus future warm starts. We show that these warm starts are asymptotically exact and converge to the solution of the MPC optimization problem. Thereby, the suboptimality of the applied control input resulting from the real-time requirements vanishes over time. Numerical show that existing real-time MPC schemes can be improved by storing optimizatising the proposed ng scheme. Copyright © 2018, The Authors. All rights reserved.

关键词： Model predictive control

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An Improved Output Feedback MPC scheme for Constrained Linear systems

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IFAC-PapersOnLine 2017年第1期50卷 15506-15511页

作者： Subramanian, Sankaranarayanan Lucia, Sergio Engell, Sebastian Process Dynamics and Operations Group DortmundTU United States Otto-von-Guericke-University Magdeburg Laboratory for Systems Theory and Automatic Control Institute of Automation Engineering Germany

We propose an output feedback model predictive control (MPC) scheme that is independent of the estimation method employed. The proposed approach is non-conservative by design as the feedback information subject to estimation errors is explicitly considered in the predictions. The proposed scheme is robust to both the plant-model mismatch and the estimation error and avoids the unnecessary conservatism introduced by other existing output feedback MPC approaches in the literature. We achieve this by making use of all the available information at every time-step and formulate a control policy with the assumption that bounds for the estimation error are available at all times. We show that the proposed scheme is recursively feasible and demonstrate its advantages using a double-integrator example. © 2017

关键词： Feedback Errors Estimation Linear systems Model predictive control Predictive control systems Robust control Constrained linear systems Constrained systems Estimation methods Feed back information Multi stage Output feedback Plant model mismatches Robust model predictive control

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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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Stabilization of discrete-time switched linear systems: Lyapunov-Metzler inequalities versus S-procedure characterizations

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IFAC-PapersOnLine 2017年第1期50卷 3412-3417页

作者： Kundu A. Daafouz J. Heemels W.P.M.H. Robert Bosch Centre for Cyber-Physical Systems Indian Institute of Science Bangalore India Centre for Research in Automatic Control of Nancy University of Lorraine France Control Systems Technology Group Department of Mechanical Engineering Eindhoven University of Technology Netherlands

In this paper we study connections between Lyapunov-Metzler inequalities and S-procedure characterizations in the context of stabilizing discrete-time switched linear systems using min-switching strategies. We propose two generalized versions of S-procedure characterization along the lines of the generalized versions of Lyapunov-Metzler inequalities recently proposed in the literature. It is shown that the existence of a solution to the generalized version(s) of Lyapunov-Metzler inequalities is equivalent to the existence of a solution to the generalized version(s) of S-procedure characterization with a restricted choice of the scalar quantities involved in the latter. This recovers some of our earlier works on the classical Lyapunov-Metzler inequalities as a special case. We also highlight and discuss an open question of whether the generalized versions of S-procedure characterization are strictly less conservative than the generalized versions of Lyapunov-Metzler inequalities, which in turn are equivalent to periodic stabilizability as was recently shown. © 2017

关键词： Discrete-time switched linear systems Lyapunov-Metzler inequalities matrix inequalities min-switching strategy S-procedure characterizations stabilizability

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