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Finding Consensus Without Computation

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IEEE Robotics and Automation Letters 2018年第3期3卷 1346-1353页

作者： Ozdemir, Anil Gauci, Melvin Bonnet, Salome Groß, Roderich Department of Automatic Control and Systems Engineering University of Sheffield SheffieldS102TN United Kingdom Wyss Institute for Biologically Inspired Engineering Harvard University BostonMA02138 United States

A canonical problem for swarms of agents is to collectively choose one of multiple options in their environment. We present a novel control strategy for solving this problem-the first to be free of arithmetic computation. The agents do not communicate with each other nor do they store run-time information. They have a line-of-sight sensor that extracts one ternary digit of information from the environment. At every time step, they directly map this information onto constant-value motor commands. We evaluate the control strategy with both simulated and physical e-puck robots. By default, the robots are expected to choose, and move to, one of two options of equal value. The simulation studies show that the strategy is robust against sensory noise, scalable to large swarm sizes, and generalizes to the problems of choosing between more than two options or between unequal options. The experiments-50 trials conducted with a group of 20e-puck robots-show that the group achieves consensus in 96 of the trials. Given the extremely low hardware requirements of the strategy, it opens up new possibilities for the design of swarms of robots that are small in size (ll 10-3m) and large in numbers (103). © 2016 IEEE.

关键词： Multipurpose robots

On closed-loop dynamics of ADMM-based MPC

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arXiv 2019年

作者： Darup, Moritz Schulze Book, Gerrit Automatic Control Group Department of Electrical Engineering and Information Technology Universität Paderborn Warburger Straße 100 Paderborn33098 Germany

This paper studies the closed-loop dynamics of linear systems under approximate model predictive control (MPC). More precisely, we consider MPC implementations based on a finite number of ADMM iterations per time-step. We first show that the closed-loop dynamics can be described based on a nonlinear augmented model. We then characterize an invariant set around the augmented origin, where the dynamics become linear. Finally, we investigate the performance of the approximate MPC for various choices of the ADMM parameters based on a comprehensive numerical benchmark. Copyright © 2019, The Authors. All rights reserved.

关键词： Model predictive control

Magnetohydrodynamic wave mode identification in circular and elliptical sunspot umbrae: evidence for high order modes

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arXiv 2022年

作者： Albidah, Abdulrahman B. Fedun, V. Aldhafeeri, A.A. Ballai, I. Brevis, W. Jess, D.B. Higham, J. Stangalini, M. Silva, S.S.A. Verth, G. Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Department of Mathematics College of Science Al-Zulfi Majmaah University Al-Majmaah 11952 Saudi Arabia Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom Mathematics and Statistic Department Faculty of Science King Faisal University Al-Hassa P.O. Box 400 Hofuf31982 Saudi Arabia School of Engineering Pontificia Universidad Católica de Chile Chile Astrophysics Research Centre School of Mathematics and Physics Queen's University BelfastBT7 1NN United Kingdom Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States School of Environmental Sciences Department of Geography and Planning University of Liverpool Roxby Building LiverpoolL69 7ZT United Kingdom ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy

In this paper we provide clear direct evidence of multiple concurrent higher order magnetohydrodynamic (MHD) modes in circular and elliptical sunspots by applying both Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques on solar observational data. These techniques are well documented and validated in the areas of fluid mechanics, hydraulics, and granular flows, yet are relatively new to the field of solar physics. While POD identifies modes based on orthogonality in space and it provides a clear ranking of modes in terms of their contribution to the variance of the signal, DMD resolves modes that are orthogonal in time. The clear presence of the fundamental slow sausage and kink body modes, as well as higher order slow sausage and kink body modes have been identified using POD and DMD analysis of the chromospheric Hα line at 6562.808 Å for both the circular and elliptical sunspots. Additionally, to the various slow body modes, evidence for the presence of the fast surface kink mode was found in the circular sunspot. All the MHD modes patterns were cross-correlated with their theoretically predicted counterparts and we demonstrated that ellipticity cannot be neglected when interpreting MHD wave modes. The higher-order MHD wave modes are even more sensitive to irregularities in umbral cross-sectional shapes, hence this must be taken into account for more accurate modelling of the modes in sunspots and pores. Copyright © 2022, The Authors. All rights reserved.

关键词： Magnetohydrodynamics

Slow magnetoacoustic waves in gravitationally stratified two-fluid plasmas in strongly ionised limit

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arXiv 2020年

作者： Alharbi, Abdulaziz Ballai, I. Fedun, V. Verth, G. Plasma Dynamics Group School of Mathematics and Statistics University of Sheffield Housnfield Road Hicks Building SheffieldS3 7RH United Kingdom Department of Mathematics Jamoum University College Umm Al-Qura University Jamoum Makkah Saudi Arabia Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom

The plasma dynamics at frequencies comparable with collisional frequency between various species has to be described in multi-fluid framework, where collisional interaction between particles is an important ingredient. In our study we will assume that charged particles are strongly coupled, meaning that they form a single fluid that interacts with neutrals, therefore we will employ a two-fluid model. Here we aim to investigate the evolutionary equation of slow sausage waves propagating in a gravitationally stratified flux tube in the two-fluid solar atmosphere in a strongly ionised limit using an initial value analysis. Due to the collisional interaction between massive particles (ions and neutrals) the governing equations are coupled. Solutions are sought in the strongly ionised limit and the density ratio between neutrals and charged particles is a small parameter. This limit is relevant to the upper part of the chromosphere. Our results show that slow sausage waves associated with charged particles propagate such that their possible frequency is affected by a cut-off due to the gravitational stratification. In contrast, for neutral acoustic waves the cut-off value applies on their wavelength and only small wavelength waves are able to propagate. Slow modes associated to neutrals are driven by the collisional coupling with ions. © 2020, CC0.

关键词： Magnetohydrodynamics

The Propagation of Coherent Waves Across Multiple Solar Magnetic Pores

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arXiv 2022年

作者： Grant, Samuel D.T. Jess, D.B. Stangalini, M. Jafarzadeh, S. Fedun, V. Verth, G. Keys, P.H. Rajaguru, S.P. Uitenbroek, H. Macbride, C.D. Bate, W. Gilchrist-Millar, C.A. 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 ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Schöneckstr. 6 Freiburg79104 Germany Rosseland Centre for Solar Physics University of Oslo P.O. Box 1029 Blindern Oslo0315 Norway 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 Indian Institute of Astrophysics Bangalore34 India National Solar Observatory University of Colorado Boulder 3665 Discovery Drive BoulderCO80303 United States

Solar pores are efficient magnetic conduits for propagating magnetohydrodynamic wave energy into the outer regions of the solar atmosphere. Pore observations often contain isolated and/or unconnected structures, preventing the statistical examination of wave activity as a function of atmospheric height. Here, using high resolution observations acquired by the Dunn Solar Telescope, we examine photospheric and chromospheric wave signatures from a unique collection of magnetic pores originating from the same decaying sunspot. Wavelet analysis of high cadence photospheric imaging reveals the ubiquitous presence of slow sausage mode oscillations, coherent across all photospheric pores through comparisons of intensity and area fluctuations, producing statistically significant in-phase relationships. The universal nature of these waves allowed an investigation of whether the wave activity remained coherent as they propagate. Utilizing bi-sector Doppler velocity analysis of the Ca II 8542 Å line, alongside comparisons of the modeled spectral response function, we find fine-scale 5 mHz power amplification as the waves propagate into the chromosphere. Phase angles approaching zero degrees between co-spatial line depths spanning different line depths indicate standing sausage modes following reflection against the transition region boundary. Fourier analysis of chromospheric velocities between neighboring pores reveals the annihilation of the wave coherency observed in the photosphere, with examination of the intensity and velocity signals from individual pores indicating they behave as fractured wave guides, rather than monolithic structures. Importantly, this work highlights that wave morphology with atmospheric height is highly complex, with vast differences observed at chromospheric layers, despite equivalent wave modes being introduced into similar pores in the photosphere. © 2022, CC BY.

关键词： Magnetohydrodynamics

An Early Stage Researcher's Primer on systems Medicine Terminology

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Network and Systems Medicine

Network and systems Medicine 2021年第1期4卷 2-50页

作者： Zanin, Massimiliano Aitya, Nadim A.A. Basilio, José Baumbach, Jan Benis, Arriel Behera, Chandan K. Bucholc, Magda Castiglione, Filippo Chouvarda, Ioanna Comte, Blandine Dao, Tien-Tuan Ding, Xuemei Pujos-Guillot, Estelle Filipovic, Nenad Finn, David P. Glass, David H. Harel, Nissim Iesmantas, Tomas Ivanoska, Ilinka Joshi, Alok Boudjeltia, Karim Zouaoui Kaoui, Badr Kaur, Daman Maguire, Liam P. McClean, Paula L. McCombe, Niamh De Miranda, João Luís Moisescu, Mihnea Alexandru Pappalardo, Francesco Polster, Annikka Prasad, Girijesh Rozman, Damjana Sacala, Ioan Sanchez-Bornot, Jose M. Schmid, Johannes A. Sharp, Trevor Solé-Casals, Jordi Spiwok, Vojtěch Spyrou, George M. Stalidzans, Egils Stres, Blaa Sustersic, Tijana Symeonidis, Ioannis Tieri, Paolo Todd, Stephen Van Steen, Kristel Veneva, Milena Wang, Da-Hui Wang, Haiying Wang, Hui Watterson, Steven Wong-Lin, Kongfatt Yang, Su Zou, Xin Schmidt, Harald H.H.W. Centro de Tecnología Biomédica Universidad Politécnica de Madrid Madrid Spain Intelligent Systems Research Centre School of Computing Engineering and Intelligent Systems Ulster University Ulster United Kingdom Center for Physiology and Pharmacology Institute of Vascular Biology and Thrombosis Research Medical University of Vienna Vienna Austria TUM School of Life Sciences Weihenstephan Technical University of Munich Freising Germany Holon Israel CNR National Research Council IAC Institute for Applied Computing Rome Italy Lab of Computing Medical Informatics and Biomedical Imaging Technologies School of Medicine Aristotle University of Thessaloniki Thessaloniki Greece Université Clermont Auvergne INRAE UNH Plateforme d'Exploration du Métabolisme MetaboHUB Clermont Clermont-Ferrand France Université de Technologie de Compiègne Compiègne France Labex MS2T Control of Technological Systems-of-Systems CNRS and Université de Technologie de Compiègne Compiègne France Faculty of Engineering University of Kragujevac Kragujevac Serbia Kragujevac Serbia Steinbeis Advanced Risk Technologies Institute Doo Kragujevac Kragujevac Serbia Pharmacology and Therapeutics School of Medicine Galway Neuroscience Centre National University of Ireland Galway Ireland School of Computing Ulster University Ulster United Kingdom Holon Israel Department of Mathematics and Natural Sciences Kaunas University of Technology Kaunas Lithuania Faculty of Computer Science and Engineering Ss. Cyril and Methodius University Skopje Macedonia Medicine Faculty Université Libre de Bruxelles CHU de Charleroi Charleroi Belgium Northern Ireland Centre for Stratified Medicine Biomedical Sciences Research Institute Ulster University Ulster United Kingdom Escola Superior de Tecnologia e Gestão Instituto Politécnico de Portalegre Portalegre Portugal Instituto Superior Técnico Universidade de Lisboa Lisboa Portugal Faculty of Automatic Control and Computers University Politehnica of B

Background: systems Medicine is a novel approach to medicine, that is, an interdisciplinary field that considers the human body as a system, composed of multiple parts and of complex relationships at multiple levels, and further integrated into an environment. Exploring systems Medicine implies understanding and combining concepts coming from diametral different fields, including medicine, biology, statistics, modeling and simulation, and data science. Such heterogeneity leads to semantic issues, which may slow down implementation and fruitful interaction between these highly diverse fields. Methods: In this review, we collect and explain more than100 terms related to systems Medicine. These include both modeling and data science terms and basic systems medicine terms, along with some synthetic definitions, examples of applications, and lists of relevant references. Results: This glossary aims at being a first aid kit for the systems Medicine researcher facing an unfamiliar term, where he/she can get a first understanding of them, and, more importantly, examples and references for digging into the topic. © Massimiliano Zanin et al., 2021;Published by Mary Ann Liebert, Inc. 2021.

关键词： Semantics

Sausage, kink, and fluting MHD wave modes identified in solar magnetic pores by Solar Orbiter/PHI

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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

Impedance Matching for an Inductive Harvesting Transducer

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Impedance Matching for an Inductive Harvesting Transducer

International Conference on Electrical Machines, Drives and Power systems (ELMA)

作者： Juan A. GARRIGA Hugo VALDERRAMA-BLAVI David GARCÍA-ELVIRA J.A. BARRADO Àngel CID-PASTOR Department of Computer Science and Industrial Engineering Universitat de Lleida (UDL) Lleida Spain Automatic Control and Industrial Electronics Group (GAEI) Universitat Rovira i Virgili (URV) Tarragona Spain

ISBN: (纸本)9781728114149

This paper presents an inductive transducer coupled to an articulated device for harvesting applications. This device, taking advantage of the sway of the waves of the sea, produces a linear oscillating motion in a solenoid-magnet. Using some magnetic fundamentals, a model of the transducer is deduced. This model is then extended to a harvesting device made with three transducers. Different transducer prototypes, with different number of coil turns, wire gauge, and magnets, have been developed to optimize it. The energy harvested form the final transducer array is processed electronically to charge an autonomous system battery. To maximize the energy collected the principle of impedance matching is used. Thus, the output impedance of the transducer array must match the converter input impedance. A buck-boost hybrid converter (HBB) controlled to behave as a Loss Free Resistor is proposed as impedance adaptor circuit. After the theoretical analysis, several simulation and experimental results are given.

关键词： Transducers Impedance Impedance matching Surface impedance Windings Magnetic flux Generators

Active Battery Balancing Via a Switched DC/DC Converter: Description and Performance Analysis

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Active Battery Balancing Via a Switched DC/DC Converter: Des...

International Conference on Electrical Machines, Drives and Power systems (ELMA)

作者： David GARCÍA ELVIRA Hugo VALDERRAMA BLAVÍ Josep María BOSQUE MONCUSÍ Àngel CID PASTOR Juan Antonio GARRIGA CASTILLO Luis MARTÍNEZ SALAMERO Automatic Control and Industrial Electronics Group (GAEI) Universitat Rovira i Virgili (URV) Tarragona Spain Department of Computer Science and Industrial Engineering Universitat de Lleida (UDL) Lleida Spain

ISBN: (纸本)9781728114149

This paper presents a new converter-based active balancing topology. This equalizer topology consists of a single non-isolated DC/DC converter and cell-to-cell power routing via controlled switches, which are operated as power multiplexers. The design and control strategy of the equalizer are explained. Its performance is assessed in simulation. The equalizer balances an imbalanced battery pack of five monobloc batteries, compensating the initial SOC deviations and keeping the pack balanced from then on. The influence of four battery parameters in SOC divergence is analyzed.

关键词： Batteries State of charge Equalizers Topology control systems Integrated circuit modeling Load modeling