Suchergebnisse

"Climate warming and disorder are the consequence of a free trade economic growth model that has failed to anticipate its physical impact on the environment. This failure reveals a lack of interaction between economists and scientists, long separated from an academic standpoint. The separation is artificial. This book shows that the free trade concept of David Ricardo and that of the Sadi Carnot thermodynamic cycle, both developed at the dawn of the Industrial Revolution, are amazingly close to each other. The analogy between the two cycles helps understand the fundamental mechanism of free trade. Irreversible processes, such as the release of CO2 by fossil fuel burning, have increased the Boltzmann entropy level. It has generated climate warming and disorder, a phenomenon accelerated by a growth model largely based on delocalization of industrial production to low wage countries. Major irreversible phenomena such as melting of all arctic ice including the Greenland ice sheets can be expected within 1000 years that can only be avoided by active removal of atmospheric CO2, whose cost can be calculated based on the entropy laws of Clausius and Boltzmann"--

4. Les conditions thermodynamiques d'un retour à l'équilibreLA BIOSPHÈRE COMME MACHINE DE CARNOT ENTROPIQUE; LA MACHINE DE CARNOT ET L'EFFET DE LA FINITUDE DE L'ENVIRONNEMENT; ÉNERGIE ET ENTROPIE DANS LA BIOSPHÈRE; LA RUPTURE D'ÉQUILIBRE; DE MALTHUS À LA COP 21 : ÉPUISEMENT DES RESSOURCES EN ÉNERGIE OU EXCÈS D'ENTROPIE?; 5. Pourquoi rejetons-nous tant de carbone dans l'atmosphère?; LA LIMITE ACCEPTABLE DES ÉMISSIONS DE CARBONE; LA RÉPARTITION DES ÉMISSIONS DE CARBONE; REJETS ENTROPIQUES ET COMPLEXITÉ DES SOCIÉTÉS MODERNES; 6. Les moyens d'un retour à l'équilibre.

The functional properties of cuprates are strongly determined by the doping state and carrier density. We present an oxygen doping study of YBa2Cu3O7-δ (YBCO) thin films from underdoped to overdoped state, correlating the measured charge carrier density, nH, the hole doping, p, and the critical current density, Jc. Our results show experimental demonstration of strong increase of Jc with nH, up to Quantum Critical Point (QCP), due to an increase of the superconducting condensation energy. The ultra-high Jc achieved, 90 MA cm−2 at 5 K corresponds to about a fifth of the depairing current, i.e. a value among the highest ever reported in YBCO films. The overdoped regime is confirmed by a sudden increase of nH, associated to the reconstruction of the Fermi-surface at the QCP. Overdoping YBCO opens a promising route to extend the current carrying capabilities of rare-earth barium copper oxide (REBCO) coated conductors for applications. ; The authors acknowledge financial support from Spanish Ministry of Economy and Competitiveness through the "Severo Ochoa" Programme for Centres of Excellence in R&D (Grant No. SEV-2015-0496), the EU ULTRASUPERTAPE (ERC-2014-ADG-669504) and EUROTAPES project (FP7-NMP-Large-2011-280432), and the Spanish CONSOLIDER Excellence Network (Grant No. MAT2015-68994-REDC), COACHSUPENERGY project (Grant No. MAT2014-56063-C2-1-R) and SuMaTe project (RTI2018-095853-B-C21), both cofinanced by the European Regional Development Fund, and from the Catalan Government with Grant No. 2014-SGR-753 and 2017-SGR-1519. Authors also thank the network collaboration of EU COST action NANOCOHYBRI CA16218.We also acknowledge the Scientific Services at ICMAB. We thank Juri Banchewski for some of the last transport experiments. A.S. is grateful for illuminating discussions on the manuscript with Stephan Steinhauer (KTH, Sweden). ; Peer reviewed

High voltage direct current super-grids are one attractive solution for the transmission of bulk power of renewable electricity over long distances. Their protection is still an issue and superconducting fault current limiters (SCFCL) offer attractive perspectives. However, the actual superconducting tapes are not yet properly designed for operation at high voltages (>100 kV): The electric field developed during the current limitation is still too low (approximately 50 V/m for 50 ms) and the limiter requires too long lengths of tape. The European project FASTGRID aims at improving the properties of the REBCO tapes to enhance significantly (by 2-3 times) the electric field limit and so the economical SCFCL attractiveness. We use advanced THEVA tapes. Substantial improvements are also planned on the stabilizer (shunt) layer. Several shunt ways are under investigations. Other improvement on the tape properties will be carried out, namely the increase of the normal zone propagation velocity by at least one order of magnitude, with the help of the innovative current flow diverter architecture. The optimized conductor will be used in a SCFCL module (≈1.5 kA-50 kV) tested at 65 K. We will monitor the temperature along the conductor using an attached optical fibre. FASTGRID will also develop innovative tapes based on sapphire substrate, which can tolerate very high electric fields, in the range of kilovolts per meter. Validated on the laboratory scale, this game-changing technology needs to be implemented at long lengths with an industrial process. We will provide an overview of the project and its first results. ; This work was supported by the European Union's Horizon 2020 research and innovative programme under Grant 721019. ; Peer reviewed