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- Murari, A., et al.
(author)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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In: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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- Joffrin, E., et al.
(author)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Research review (peer-reviewed)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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- Bolognesi, A., et al.
(author)
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High photoluminescence efficiency in substituted polythiophene aggregates
- 2003
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In: Synthetic metals. - 0379-6779 .- 1879-3290. ; 139:2, s. 303-310
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Journal article (peer-reviewed)abstract
- In this paper we discuss the optical (absorption and photoluminescence) and solvatochromic properties of a newly synthesized alternating copolymer based on poly(3-alkylthiophene) structure. In this copolymer an unsubstituted thiophene ring is linked to a 3-alkyl-substituted thiophene, the two repeating units being alternated in the copolymer chains. Moreover, a bulky group, THP, with high steric hindrance has been introduced in the side chain. This copolymer, designed to preserve the backbone planarity of polythiophenes and to prevent a close packing arrangement through the non-regioregular insertion of the bulky substituted monomer, shows high PL quantum yield in the solid state and in solution aggregates. The electroluminescence of this copolymer is reported for a simple single layer device. © 2003 Elsevier Science B.V. All rights reserved.
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| 9. |
- Morf, Andrea, 1968, et al.
(author)
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Towards sustainability of marine governance: Challenges and enablers for stakeholder integration in transboundary marine spatial planning in the Baltic Sea
- 2019
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In: Ocean & Coastal Management. - : Elsevier BV. - 0964-5691. ; 177, s. 200-212
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Journal article (peer-reviewed)abstract
- Integrating stakeholder knowledge, views and needs in marine or maritime spatial planning (MSP) processes is important from a governance and social sustainability perspective both for MSP practitioners and for the evolving field of MSP research. Transboundary MSP appears particularly challenging for participation, which is why it is important to identify opportunities and address obstacles for stakeholder integration in this specific context. This article examines how stakeholder integration is currently practiced in the Baltic Sea Region (BSR), an enclosed sea where policy coherence and addressing conflicting interests across borders are especially relevant. It synthesises a range of challenges and enablers for stakeholder participation and mobilisation that have emerged from two transboundary MSP research and development projects, BaltSpace and Baltic SCOPE. The article finds that with the exception of statutory authorities, stakeholder engagement in the BSR is mostly limited to self-motivated stakeholders and consultation rather than more inclusive forms of participation. This can reduce the quality and legitimacy of MSP processes and risks to concentrate power in the hands of a small group of actors. For transboundary stakeholder integration to become more interactive and effective, five types of challenges need attention, regarding a) timing, b) governance systems, c) capacity and processes, d) stakeholder characteristics and e) knowledge and language. These obstacles can be addressed by (1) a dedicated research and development agenda that critically reflects on integrative tools and processes, and (2) by encouraging transnational institutions in the BSR to devote more resources to transboundary stakeholder integration and adopt flexible and adaptive strategies and tools that can facilitate stakeholder involvement throughout the MSP policy cycle.
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| 10. |
- Buccolieri, R., et al.
(author)
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Flow and pollutant dispersion within the canal grande channel in venice (Italy) via CFD techniques
- 2010
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In: HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes. ; , s. 760-764
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Conference paper (peer-reviewed)abstract
- The present paper is aimed at the analysis of flow and pollutant dispersion in a portion of the Canal Grande (Grand Canal) in Venice (Italy) by means of both Computational Fluid Dynamics (CFD) FLUENT simulations and wind tunnel experiments performed at the University of Gävle (Sweden). For this application, Canal Grande can be viewed as a sort of street canyon where the bottom surface is water and bus boat emissions are the major source of pollution. Numerical investigations were made to assess the effect of the water surface on air flow and pollutant concentrations in the atmosphere. One of the challenges has been to deal with the interface between two immiscible fluids which requires ad-hoc treatment of the wall in terms of the numerical scheme adopted and the grid definition which needs to be much finer than in typical numerical airflow simulations in urban street canyons. Preliminary results have shown that the presence of water at the bottom of the street canyon modifies airflow and turbulence structure with direct consequences on concentration distribution within the domain.
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