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arXiv 2023年

作者： Albidah, A.B. Fedun, V. Aldhafeeri, A.A. Ballai, I. Jess, D.B. Brevis, W. Higham, J. Stangalini, M. Silva, S.S.A. MacBride, C.D. Verth, G. Department of Mathematics College Of Science Majmaah University P.O Box 66 Majmaah11952 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 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 School of Engineering Pontificia Universidad Católica de Chile Chile 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

Through their lifetime sunspots undergo a change in their area and shape and, as they decay, they fragment into smaller structures. Here, for the first time we analyze the spatial structure of magneto-hydrodynamic (MHD) slow body and fast surface modes in observed umbrae as their cross-sectional shape changes. The Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques were used to analyze 3 and 6 hours SDO/HMI time series of Doppler velocities at the photospheric level of approximately circular and elliptically shaped sunspots. Each time series were divided equally into time intervals, to evidence the change of the sunspots’ shape. To identify physical wave modes, the POD/DMD modes were cross-correlated with a slow body mode model using the exact shape of the umbra, whereas the shape obtained by applying a threshold level of the mean intensity for every time interval. Our results show that the spatial structure of MHD modes are affected, even by apparently small changes of the umbral shape, especially in the case of the higher-order modes. For the datasets used in our study, the optimal time intervals to consider the influence of the change in the shape on the observed MHD modes is 37 - 60 minutes. The choice of these intervals is crucial to properly quantify the energy contribution of each wave mode to the power spectrum. © 2023, CC0.

关键词： Dynamic mode decomposition

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ASYNCHRONOUS TRANSFER MODE (ATM) OPERATION VIA SATELLITE - ISSUES, CHALLENGES AND RESOLUTIONS

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 211-222页

作者： CHITRE, DM GOKHALE, DS HENDERSON, T LUNSFORD, JL MATHEWS, N COMSAT Laboratories 22300 Comsat Drive Clarksburg MD 20871 USA. Received his B.Sc. from the University of Bombay India an M.A. in mathematics from the University of Cambridge U.K. and a Ph.D. in physics from the University of Maryland. He is currently an Associate Executive Director of the Network Technology Division at COMSAT Laboratories. He has been involved in research and development activities in ISDN VSAT networks data communications and network systems and architectures. Prior to his current positions Dr. Chitre was a Principal Scientist in the Network Technology Division at COMSAT Laboratories. Dr. Chitre joined COMSAT Laboratories in 1980. He has made major contributions to the analysis and architecture of data communication ISDN and BISDN via satellite. Dr. Chitre directs and participates in the international and national standards activities in ISDN BISDN and data communication as they apply to satellite communication. He was Chairman of the Working Group on Protocols and Network Timing Function of the CCIR/CCITT Joint Ad Hoc Group on ISDN-Satellite Matters during 1990–1992. Currently he is the Chairman of the Working Group on New Technologies in the ITU Intersector Coordinating Group (ICG) on Satellite Matters. Dr. Chitre was a programme manager during 1990 and 1991 on a contract from INTELSAT on systems studies on satellite communications systems architectures for ISDN and broadband ISDN systems. Currently he is the technical manager of the DoD Contract on ATM via satellite demonstration and the programme manager for the INTELSAT contract on analysis and top-level specification of INTELSAT ISDN subnetworks and SDH compatible transport network. Department manager for ISDN/Data Communications in the Network Technology Division of COMSAT Laboratories. His responsibilities include managing the implementation of next generation telecommunication systems for fixed and mobile satellite systems. Current projects include the development of a high data rate gateway switch that provides for the

Key issues regarding the operation of the broadband integrated services digital network (BISDN) via satellite are presented herein. The specific issues, challenges, and their resolutions are detailed. In particular, the impact of error characteristics and propagation delay on the operation of BISDN via satellite is discussed. Solutions are presented for removing adverse effects and providing high-quality service to users of BISDN via satellite.

关键词： ATM BISDN

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A PRACTICAL APPROACH TO THE DESIGN, OPERATION, AND MONITORING OF INSITU SOIL-VENTING systems

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GROUND WATER MONITORING AND REMEDIATION 1990年第2期10卷 159-178页

作者： JOHNSON, PC STANLEY, CC KEMBLOWSKI, MW BYERS, DL COLTHART, JD Paul C. Johnson Ph.D. joined Shell Development Co.'s (Westhollow Research Center Room EC-649 P.O. Bo 1380 Houston TX 77251–1380) Environmental Science Department in 1987 after earning his B.S. in chemical engineering from the University of California Davis and his Ph.D. in chemical engineering from Princeton University. His current areas of research include the development and evaluation of soil treatment processes modeling and measuring transport phenomena in porous media and the development of transport models for predicting emissions and exposures used in envvironmental risk assessments. Curtis C Stanley received his degree in geology with an engineering minor from North Carolina State University in 1979. He is currently a senior hydrogeologist for Shell Oil Co. (Westhollow Research Center 2236 Two Shell Plaza Houston TX 77082) and is responsible for hydrogeologic response at Shell's retail facilities. Stanley is a Certified Professional Geological Scientist and also a Certified Ground Water Professional with the NWWA's Association of Ground Water Scientists and Engineers. He is also a member of API's Ground Water Technology Taskforce and is an EPA Peer Reviewer. Marian W. Kemblowski Ph.D. is a senior research engineer in the Environmental Science Department at Shell Development Co. (Westhollow Research Center Houston TX 77082) where he has worked since 1985. He obtained his M.S. degree in civil engineering from the Technical University of Warsaw Poland in 1973 and his Ph.D. in ground water hydrology from the Institute for Land Reclamation in Warsaw Poland in 1978. In 1980–1981 he was a visiting hydrologist in the New Mexico School of Mining and Technology. From 1981 to 1985 he worked as an assistant scientist at the University of Kansas. His principal research interests are in the areas of numerical analysis transport in porous media and ground water monitoring systems. Dallas L. Byers is a technical associate in the Environmental Science Department at Shell Development. After receivin

When operated properly, in situ soil venting or vapor extraction can be one of the most cost-effective remediation processes for soils contaminated with gasoline, solvents, or other relatively, volatile compounds. The components of soil-venting systems are typically off-the-shelf items, and the installation of wells and trenches can be done by reputable environmental firms. However, the design, operation, and monitoring of soil-venting systems are not trivial. In fact, choosing whether or not venting should be applied at a given site is a difficult decision in itself. If one decides to utilize venting, design criteria involving the number of wells, well spacing, well location, well construction, and vapor treatment systems must be addressed. A series of questions must be addressed to decide if venting is appropriate at a given site and to design cost-effective in situ soil-venting systems. This series of steps and questions forms a “decision tree” process. The development of this approach is an attempt to identify the limitations of in situ soil venting, and subjects or behavior that are currently difficult to quantify and for which future study is needed.

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New method to control cascaded doubly‐fed machines in the state space

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European Transactions on Electrical Power 1995年第1期5.0卷 55-61页

作者： Krebs, S. Dr.-Ing. Stephan Krebs (1963) received his Diploma degree in 1960 and his Dr.-Ing. degree in 1994 from the Elektrotechnisches Institut Universitat Karlsruhe/Germany. His main fields of interest are the use of modem time-discrete control methods and parallel signal processing in adjustable speed drive and power supply systems. In summer 1994 he joined the Power Group of the Department of Electrical and Computer Engineering of the University of Toronto/Canada where he is currently working on industrial controller platform for power applications. (Department of Electrical and Computer Engineering University of Toronto 10 King's College Rd. Toronto/Ontario Canada M5S 1A4 T +4 1 6/9 78-66 18 Fax +4 1 6/9 7 1-23 25)

The cascaded doublyfed machine consists of two separate induction machines which are interconnected by their rotor windings. This paper presents a general control structure for such machines, based on the principle of the field‐oriented control. An adjustable speed drive operating in subsynchronous mode is compared with an asynchronous machine‐drive system, and its advantages are shown. State‐space control methods are used to get a stable behaviour over a wide speed range. Copyright © 1995 John Wiley & Sons, Ltd.

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U.S. SEAPOWER NEW UNDERPINNING NEEDED

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Naval Engineers Journal 1981年第6期93卷 35-42页

作者： ECKHART, MYRON CAPT. MYRON ECKHART JR. USN (RET.) is currently Chief Scientist in the Autonetics Marine Systems Division of Rockwell International concentrating on digital simulation applications in system engineering. A graduate of the U.S. Naval Academy in 1945 he served in various surface assignments until 1950. Subsequent thereto after becoming an Engineering Duty Officer (ED) he had Type Commander Staff Laboratory ESO and Shipyard assignments until 1962 when he became the Military Chairman Electrical Science at the U.S. Naval Academy. In 1965 he became the Head Electrical/Electronics Design Branch Bureau of Ships remaining in this assignment until 1967 when he assumed the responsibilities of Director Ship Concept Design Division Naval Ship Engineering Center. He joined Rockwell upon retiring from the U.S. Navy in 1970 and the following year became the Manager of the Integration Programs Group involved in Model-Based Systems Analysis EM Effectiveness Submarine Control and Ship Data Multiplexing. His education includes a B.S. degree from the U.S. Naval Academy a B.S. degree in Electrical Engineering awarded by MIT in 1949 and a M.S. degree in Electrical Engineering received from The George Washington University in 1967. A former ASNE Council Member he has been an active member of ASNE since 1967.

Redesign and revitalization of the industrial base for warship acquisition are essential if the United States is to remain a first rank seapower. Navy corporate practices are predicated upon an industrial base form that no longer exists and is not recoverable. Resultant problems and limitations are at the heart of longstanding warship acquisition difficulties. Formulation of a new warship industrial base strategy is an immediate prerequisite of turning rising expectations of substantially increased building rates into reality in the late ′80s and early ′90s. © 1981 by the American Society of Naval Engineers

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control of PWM AC‐to‐DC converters using state‐space and fuzzy‐methods

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European Transactions on Electrical Power 1995年第5期5卷 301-306页

作者： Krebs, S. Oelert, K. Dr.-Ing. Stephan Krebs (1963) received his Diploma degree in 1990 and his Dr.-Ing. degree in 1994 from the Elektrotechnisches Institut Universitat Karlsruhe/Germany. His main fields of interest are the use of modern time-discrete control methods and parallel signal processing in adjusrable speed drive and power supply systems. In summer 1994. he joined the Power Group of the Department of Electrical and Computer Engineering of the University of Toronto/Canada where he is currently working on industrial controller platform for power applications. (Department of Electrical and Computer Engineering University of Toronto 10 King's College Rd. TorontoiOntario. Canada M5S 1A4 T+416/978-66 18 Fax +416/971-2325) Kai Oelert (1967) received the Electrical Engineering degree from the Elektrotechnisches Institut of the University of KarlsruhdGermany in 1993. He is currently developing software for automatic ticket-wending systems with the Company Scheidt & Bachmann Monchengladbach/Germany. (Scheidt & Bachmann GmbH Breite Str. 132 D-4 1238 Monchengladbach/Germany T+2166/266445 Fax+2166/2666 15)

Adjustable speed drive systems using AC‐machines are often fed by voltage‐source inverters. This paper presents a new strategy to control the line‐side converter. State‐space and fuzzy methods are combined to achieve a control system which includes control limits and the aspects of safety. Experiments with a drive system (30 kW) demonstrate the dynamic and steady‐state behaviour of the control. Copyright © 1995 John Wiley & Sons, Ltd.

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Parameter estimation of a second order system via nonlinear identification algorithm

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IOP Conference Series: Materials Science and engineering 2020年第1期844卷

作者： Patricio Ordaz Liliam Rodríguez-Guerrero Omar Santos Carlos Cuvas Hugo Romero Mario Ordaz-Oliver Pablo López-Pérez Electronic and Control Academic Group Research Center on Technology of Information and Systems Universidad Autónoma del Estado de Hidalgo Pachuca de Soto Hidalgo México. Universidad La Salle-Pachuca engineering School Hidalgo Pachuca de Soto México Escuela Superior de Apan Universidad Autónoma del Estado de Hidalgo. Apan Hidalgo México

In this paper, a parameter estimation for a class of second order nonlinear system is presented. The considered system, can be represented in such way that it is linear respect its parameters. Since the system output is given, only, for the second integrator a state estimation of unmeasured state variables is reconstructed via nonlinear observer based on the terminal sliding mode observer. Therefore, the main contribution of this paper deals with a full order nonlinear observer algorithm design to enhance parameter identification of a nonlinear second order system. Finally, to illustrate the theoretical performance of the proposed identification algorithm, an experimental result of a mechanical system is presented.

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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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SHIPBOARD RADIO DIRECTION FINDER INSTALLATION FOR 3 TO 30 MHZ RANGE

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NAVAL ENGINEERS JOURNAL 1968年第5期80卷 787-&页

作者： SHERRILL, WM GREEN, TC TRAVERS, DN William M. Sherrill is Manager Intercept and Direction Finding Research in the Department of Applied Electromagnetics at Southwest Research Institute San Antonio. He received his M.S. in Physics from Rice University in 1959 and his bachelor degrees in Physics and Mathematics from the University of Texas in 1957. Since joining the staff of Southwest Research Institute in 1959 he has been engaged in Naval shipboard radio direction finding research concentrating on advanced techniques of direction finding using multichannel receivers fixed antennas and the application of digital logic and computation in DF system control. He is a member of the Institute of Electrical and Electronics Engineers IEEE Professional Group on Antennas and Propagation American Astronomical Society and the Scientific Research Society of America. Terry C. Green is a Senior Research Engineer in the Department of Applied Electromagnetics at Southwest Research Institute San Antonio. He took the B.S. in Electrical Engineering from the University of Texas in 1958 and served as a commissioned officer in the U. S. Air Force from 1958 to 1962. His duties as a USAF officer included experience in military search and tracking radar and electrical support equipment design for high performance fighter aircraft. In 1962 he joined the staff of Southwest Research Institute and has been engaged in high frequency and very high frequency radio direction finding techniques for surface ship and submarine application. He is a member of the IEEE Professional Group on Antennas and Propagation and Sigma Pi Sigma. Douglas N. Travers is Director of the Department of Applied Electromagnetics at Southwest Research Institute San Antonio. He obtained his B.E. in Electrical Engineering from Johns Hopkins University in 1951 and joined the staff of Southwest Research Institute in 1951. He is the inventor of two antenna systems for high frequency direction finding designed for shipboard application and for the past 15 years has been engaged in direction finding theor

This report summarizes the practical requirements for siting radio direction finders operating in the 3 to 30 mc range and is intended primarily for the use of personnel responsible for site selection and DF antenna installation on Naval ships. The effects of reradiation from the ship's superstructure on direction finder performance are described. By the use of specific examples of shipboard installations, the merits of various siting compromises are discussed.

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Healthcare Informatics Society of Ireland

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Irish Journal of Medical Science 1999年第4期168卷 276-282页

作者： Rigby, M. Sheridan, A. Draper, R. Stephens, G. Gaffney, P. Grimson, J. Avalos, G. Comerford, F. R. Kanagaratnam, B. Dineen, B. Hamilton, I. Jung, B. Felton, E. Berry, D. Grimson, W. Rice, D. H. Healy, M. Bruce, A. Kelly, J. Carroll, T. Grogan, A. Hurl, G. A. Hyland, D. Roberts, J. Brazil, J. Callanan, I. Devitt, A. O’Brien, T. O’Sullivan, U. M. Peyton, K. Wilson, M. J. Collins, R. Crawley, L. Foley, D. Strachan, H. McBrearty, P. Murnane, R. Murphy, E. Keane, V. Mulvany, F. Sweeney, P. D. Kenny, D. O’Connell, P. R. Balfe, P. Minogue, G. Centre for Health Planning & Management Keele University Keele Staffordshire Britain St. John of God Hospital Stillorgan Hospitaller Order of St. John of God Stillorgan Dept. of Computer Science Trinity College Dublin Clinical Chemistry Laboratory Tallaght Hospital Tallaght Dublin 24 Department of Experimental Medicine Faculty of Medicine National University of Ireland Galway Department of Health Promotion Faculty of Medicine National University of Ireland Galway School of Control Systems & Electrical Engineering Dublin Institute of Technology Ireland Shared Medical Systems Malvern USA Healy Services Dublin Universal Learning Systems Ltd. Dublin The Rotunda Hospital Dublin Mater Misericordiae Hospital Dublin Institute for Healthcare Informatics Dublin First Consulting Group Macclesfield Britain Virus Reference Laboratory UCD Belfield Dublin 4 Cappagh Orthopaedic Hospital Dublin Ireland Southern Health Board Cork Mater Misericordiae Hospital Dublin 7 DSS Dublin Ltd. Ireland University College Dublin Ireland Mary Aikenhead School of Nursing St. Vincent’s Hospital Dublin Blackrock Clinic Dublin Borders Community Health Services NHS Trust Britain James Connolly Memorial Hospital Blanchardstown Dublin 15 Kildare and West Wicklow Mental Health Service for People with A Learning Disability Eastern Health Board Dublin Health Research Board Dublin General Practice Research Unit The Medical Centre Dungloe Dept. of Clinical Biochemistry Our Lady’s Hospital for Sick Children Crumlin Dublin 12

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