1,721,597 research outputs found
First operation with the JET International Thermonuclear Experimental Reactor-like wall
No full textTo consolidate International Thermonuclear Experimental Reactor (ITER) design choices and prepare for its operation, Joint European Torus (JET) has implemented ITER's plasma facing materials, namely, Be for the main wall and W in the divertor. In addition, protection systems, diagnostics, and the vertical stability control were upgraded and the heating capability of the neutral beams was increased to over 30 MW. First results confirm the expected benefits and the limitations of all metal plasma facing components (PFCs) but also yield understanding of operational issues directly relating to ITER. H-retention is lower by at least a factor of 10 in all operational scenarios compared to that with C PFCs. The lower C content (≈ factor 10) has led to much lower radiation during the plasma burn-through phase eliminating breakdown failures. Similarly, the intrinsic radiation observed during disruptions is very low, leading to high power loads and to a slow current quench. Massive gas injection using a D2/Ar mixture restores levels of radiation and vessel forces similar to those of mitigated disruptions with the C wall. Dedicated L-H transition experiments indicate a 30% power threshold reduction, a distinct minimum density, and a pronounced shape dependence. The L-mode density limit was found to be up to 30% higher than for C allowing stable detached divertor operation over a larger density range. Stable H-modes as well as the hybrid scenario could be re-established only when using gas puff levels of a few 1021 es-1. On average, the confinement is lower with the new PFCs, but nevertheless, H factors up to 1 (H-Mode) and 1.3 (at β N ≈ 3, hybrids) have been achieved with W concentrations well below the maximum acceptable level. © 2013 EURATOM
Impact of the ITER-like wall on divertor detachment and on the density limit in the JET tokamak
No full textL-mode and H-mode density limits with the ITER-like wall (ILW) have been investigated in the recent experimental campaign and compared with experiments in the JET carbon material configuration. The density limit is up to 40% higher in the JET-ILW than in the JET-CFC machine. This is linked to the formerly higher radiation fraction and, correspondingly, to earlier divertor detachment in the JET-CFC. In the ILW configuration, the discharge demonstrates a stable operation with a completely detached outer divertor in L- and H-mode. In contrary to the well-known "heating power independent" Greenwald limit, the L-mode densities limit increases moderately with rising heating power (∼ P0.4 heat) independently of the wall material. The H-L transition constitutes an effective undisruptive density limit for an H-mode plasma. Detachment itself does not trigger the H-L back transition and does not present a limit on plasma density. In the range of neutral beam heating 8-10.5 MW, no dependence of the H-mode density limit on the heating power was observed. © 2013 Euratom. Published by Elsevier B.V. All rights reserved
Shape control with the XSC during plasma current ramp-up and ramp-down at the JET tokamak
No full textThe eXtreme Shape Controller (XSC) has been originally designed to control the plasma shape at JET during the flat-top phase, when the plasma current has a constant value. During the JET 2012 experimental campaigns, the XSC has been used to improve the shape control during the transient phases of plasma current ramp-up and ramp-down. In order to avoid the saturation of the actuators with these transient phases, a Current Limit Avoidance system (CLA ) has been designed and implemented. This paper discusses the CLA algorithm and presents the experimental results achieved at JET during the 2012 campaigns using the XSc. © 2013 IEEE
Food security and land grabbing in low-income countries of the Sub-Saharan Africa
Full text linkThe fight against hunger and poverty has long been at the heart of international policies in favour of Less Developed Countries. The first two Sustainable Development Goals (SDGs) of 2030 Agenda strategy are just "No poverty" and "Zero Hunger". Notwithstanding the results achieved in the recent past, in the poorest and low-income Countries, especially Sub-Saharan Africa, lots of people continue to suffer from hunger and poverty. In these Countries, the perspective for economic growth and development of agricultural productivity, as currently measured, is not able to assure the elimination of poverty and hunger. These problems will probably tend to focus right in this area, where the maximum demographic increase is also forecast. Despite of the increase of agricultural productivity is paramount for food security, in the Poorest Countries it is, up to now, strictly linked to farm new lands. In the last years, in the Sub-Saharan Africa low income Countries, investments in new lands have been affected by Land Grabbing. The aim of this paper is to verify whether and to what extent the Land Grabbing operations have affected both the variation of agricultural land and the development of agricultural activities for food security in the Countries concerned
INTERNATIONAL TRENDS IN SOCIAL AND ENVIRONMENTAL ISSUES. AN ANALYSIS OF THE SOSTAINABILITY STANDARDS G3
No full textFirst nitrogen-seeding experiments in JET with the ITER-like Wall
No full textIn this contribution we present results from the first N2 seeding experiments in JET performed after installation of the ITER-like Wall. Gas balance measurements for seeded L-mode discharges indicate very strong N2 retention as well as a potential increase in D2 retention. The possible influence of ammonia production on this apparent retention is discussed. Plasma parameters and impurity content were monitored throughout the seeded discharges as well as during subsequent clean-up discharges. These experiments give first insight into phenomena related to the use of nitrogen as seeding gas in JET with the ITER-like Wall, such as ammonia production and nitrogen legacy. © 2013 Elsevier B.V. All rights reserved
Limits and potential of organic farming towards a more sustainable European agri-food system
Full text linkPurpose: The aim of this paper is to assess whether the current European target to increase the areas under organic farming to 25% by 2030 is attainable and whether the simple increase in areas under organic farming may be sufficient to improve the sustainability of European agriculture. Design/methodology/approach: The analysis has been carried out through a simple data processing related to areas under organic farming, for the period 2012–2020 (Eurostat database), in order to highlight the trends of areas under organic farming and to verify whether the annual average change rates may be compatible with the stated target. Findings: The analysis showed that organic farming has a productive weight not corresponding to the amount on the total of the areas under cultivation and a small impact on the total of food consumption. It is a plausible hypothesis, the one that shows the increase in areas under organic farming will engage forms of agriculture and farms that, already, are more sustainable, so the achievement of 25% target will not particularly impact the European potential productive and the less environmental sustainable forms of agriculture. Originality/value: This paper contributes to the debate, involving scientific community, policy maker and civil society, about the real contribution of organic farming to sustainability, and it will be developed in future research
L'ETICHETTA CLIMATICA SUI PRODOTTI ALIMENTARI: UN NUOVO APPROCCIO DELL'INDUSTRIA ALIMENTARE
No full textRiassunto
Il riscaldamento globale e i cambiamenti climatici sono problematiche da tempo in discussione che
influenzano le scelte politiche e impongono cambiamenti nelle abitudini di consumo e negli stili di vita.
Anche il settore alimentare contribuisce in modo rilevante ai cambiamenti climatici in termini di emissione
di gas serra, in tutte le fasi della filiera produttiva.
Questo lavoro ha l’obiettivo di evidenziare il contributo dell’introduzione dell’etichetta climatica apposta
sui prodotti alimentari alla tutela dell’ambiente e al migliore dialogo con il consumatore. In particolare,
vengono evidenziate le azioni strategiche atte a corresponsabilizzare gli attori sociali e gli effetti in termini
di competitività e di influenza sulle scelte d’acquisto.
A tal fine,vengono analizzati i limiti e le potenzialità dei concetti di “food miles” e di “carbon footprint” e le
possibilità di realizzazione di un sistema di etichettatura omogeneo che fornisca ai consumatori indicazioni
chiare sulle performance dei prodotti e li orienti verso scelte di acquisto più consapevoli e sostenibili
Empirical study of the environmental management of Italy’s drinking water supply
No full textItalian drinking water supply structure includes two main systems: tap water and bottled water. Thanks
to the first, drinking water is available almost all around domestic territory while bottled water represents
one of the ways to make water available where and/or when there is no tap water. Due to the
changing eating habits and lifestyles bottled water has become a large consumption beverage provoking
a growth rate of the drinking water industry. The objective of this study is the analysis of the key
environmental issues related to the Italian drinking water supply systems and of practical solutions for
improving the sustainability of the both systems. The results obtained highlight that bottled water is less
environmentally friendly than tap water because it requires much higher material (130–154 kg/m3) and
energy (1000–4900 MJ/m3) inputs than tap water (respectively equal to 0.5–1.3 kg/m3 and 2–3 MJ/m3)
and generates more waste (130–155 kg/m3 of bottled water versus 0.3–0.7 kg/m3 of tap one). Among the
different possible opportunities, to improve the sustainability of bottled water the authors present different
options mainly related to the recycling of post-consumption bottles and the organization of logistics.
With regard to tap water the main points of criticism are water losses and energy costs. Quantitative
evaluations of the given alternatives make this analysis a concrete example of how it is possible (and necessary)
for industrial sectors to implement environmental management to settle company development
and environmental sustainability
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