723 research outputs found

    Analysis of Human and Agent Characteristics on Human-Agent Team Performance and Trust

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    The human-agent team represents a new construct in how the United States Department of Defense is orchestrating mission planning and mission accomplishment. In order for mission planning and accomplishment to be successful, several requirements must be met: a firm understanding of human trust in automated agents, how human and automated agent characteristics influence human-agent team performance, and how humans behave. This thesis applies a combination of modeling techniques and human experimentation to understand the concepts aforementioned. The modeling techniques used include static modeling in SysML activity diagrams and dynamic modeling of both human and agent behavior in IMPRINT. Additionally, this research consisted of human experimentation in a dynamic, event-driven, teaming environment known as Space Navigator. Both the modeling and the experimenting depict that the agent\u27s reliability has a significant effect upon the human-agent team performance. Additionally, this research found that the age, gender, and education level of the human user has a relationship with the perceived trust the user has in the agent. Finally, it was found that patterns of compliant human behavior, archetypes, can be created to classify human users

    The role of isotope mass and transport for H-mode access in tritium containing plasmas at JET with ITER-like wall

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    Special Issue Featuring the Invited Talks from the 48th EPS Conference on Plasma Physics, 27 June - 1 July 2022The required heating power, , to access the high confinement regime (H-mode) in tritium containing plasmas is investigated in JET with ITER-like wall at a toroidal magnetic field of T and a plasma current of MA. , also referred to as the L-H power threshold, is determined in plasmas of pure tritium as well as mixtures of hydrogen with tritium (H-T) and mixtures of deuterium with tritium (D-T), and is compared to the L-H power threshold in plasmas of pure hydrogen and pure deuterium. It is found that, for otherwise constant parameters, is not the same in plasmas with the same effective isotope mass, , when they differ in their isotope composition. Thus, is not sufficient to describe the isotope effect of in a consistent manner for all considered isotopes and isotope mixtures. The electron temperature profiles measured at the L-H transition in the outer half of the radius are very similar for all isotopes and isotope mixtures, despite the fact that the L-H power threshold varies by a factor of about six. This finding, together with the observation of an offset linear relation between the L-H power threshold, , and an effective heat diffusivity, , indicates that the composition-dependent heat transport in the low confinement mode (L-mode) determines, how much power is needed to reach the necessary electron temperatures at the edge, and hence PLH.This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200—EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. G Birkenmeier received funding from the Helmholtz Association under Grant No. VH-NG-1350Peer Reviewed"Article signat per 50 autors/es: G Birkenmeier, E R Solano, I S Carvalho, J C Hillesheim, E Delabie, E Lerche, D Taylor, D Gallart, M J Mantsinen, C Silva, C Angioni, F Ryter, P Carvalho, M Fontana, E Pawelec, S A Silburn, P Sirén, S Aleiferis, J Bernardo, A Boboc, D Douai, P Puglia, P Jacquet, E Litherland-Smith, I Jepu, D Kos, H J Sun, A Shaw, D King, B Viola, R Henriques, K K Kirov, M Baruzzo, J Garcia, A Hakola, A Huber, E Joffrin, D Keeling, A Kappatou, M Lennholm, P Lomas, E de la Luna, C F Maggi, J Mailloux, M Maslov, F G Rimini, N Vianello, G Verdoolaege, H Weisen, M Wischmeier and JET Contributors"Postprint (published version

    Gyrokinetic analysis and simulation of pedestals, to identify the culprits for energy losses using fingerprints

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    Fusion performance in tokamaks hinges critically on the efficacy of the Edge Transport Barrier (ETB) at suppressing energy losses. The new concept of fingerprints is introduced to identify the instabilities that cause the transport losses in the ETB of many of today's experiments, from widely posited candidates. Analysis of the Gyrokinetic-Maxwell equations, and gyrokinetic simulations of experiments, find that each mode type produces characteristic ratios of transport in the various channels: density, heat and impurities. This, together with experimental observations of transport in some channel, or, of the relative size of the driving sources of channels, can identify or determine the dominant modes causing energy transport. In multiple ELMy H-mode cases that are examined, these fingerprints indicate that MHD-like modes are apparently not the dominant agent of energy transport; rather, this role is played by Micro-Tearing Modes (MTM) and Electron Temperature Gradient (ETG) modes, and in addition, possibly Ion Temperature Gradient (ITG)/Trapped Electron Modes (ITG/TEM) on JET. MHD-like modes may dominate the electron particle losses. Fluctuation frequency can also be an important means of identification, and is often closely related to the transport fingerprint. The analytical arguments unify and explain previously disparate experimental observations on multiple devices, including DIII-D, JET and ASDEX-U, and detailed simulations of two DIII-D ETBs also demonstrate and corroborate this
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