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Sökning: WFRF:(Diez M) > Kungliga Tekniska Högskolan

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1.
  • Acharya, B. S., et al. (författare)
  • Introducing the CTA concept
  • 2013
  • Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
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2.
  • Corre, Y., et al. (författare)
  • Testing of ITER-grade plasma facing units in the WEST tokamak: Progress in understanding heat loading and damage mechanisms
  • 2023
  • Ingår i: Nuclear Materials and Energy. - : Elsevier BV. - 2352-1791. ; 37
  • Tidskriftsartikel (refereegranskat)abstract
    • Assessing the performance of the ITER design for the tungsten (W) divertor Plasma Facing Units (PFUs) in a tokamak environment is a high priority issue to ensure efficient plasma operation. This paper reviews the most recent results derived from experiments and post-mortem analysis of the ITER-grade PFUs exposed in the WEST tokamak and the associated modelling, with a focus on understanding heat loading and damage evolution. Several shaping options, sharp or chamfered leading edge (LE), unshaped or shaped blocks with a toroidal bevel as foreseen in ITER, were investigated, under steady state heat fluxes of up to 120 MW⋅m−2 and 6 MW⋅m−2 on the sharp LE and top surface of the block, respectively. A very high spatial resolution (VHR) infrared (IR) camera (0.1 mm/pixel) was used to derive the temporal and surface distribution of the temperature and heat load on the castellated tungsten blocks for different geometric alignment and plasma conditions. Photonic modelling was required to reproduce the IR measurements in particular in the toroidal and poloidal gaps of the mono-block (MB) stacks where high apparent temperatures are observed. Specular reflection is found to be the dominant emitter in these parts of the blocks. W-cracking was observed on the leading edge of the blocks already within the first phase of plasma operation, during which the divertor was equipped with unshaped PFUs, including some intentionally misaligned blocks. Numerical analysis taking into account softening processes and mechanical stresses, revealed brittle failure due to transients as the dominant failure mechanisms. Ductile failure was observed in one particular block used for the melting experiment, therefore under extremely high steady state heat load conditions. W-melting achieved on actively cooled PFU exhibits specific features: shallow melting and slow melt displacement. Plasma exposure of pre-damaged PFUs at various damage levels (crack network and melted droplets) was carried out under high heat load conditions with several hours of cumulated plasma duration. IR data and preliminary surface analyses show no evidence of significant degradation damage progression under these conditions.
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3.
  • Tichit, Q., et al. (författare)
  • Infrared detection of tungsten cracking on actively cooled ITER-like component during high power experiment in WEST
  • 2023
  • Ingår i: Nuclear Materials and Energy. - : Elsevier BV. - 2352-1791. ; 37
  • Tidskriftsartikel (refereegranskat)abstract
    • The consequences of tungsten (W) damaging processes, such as cracking and melting, on divertor lifetime and plasma operation are high priority issues for ITER. A sustained melting experiment was conducted in WEST using a 2 mm deep groove geometry on the upstream mono-block (MB) to overexpose the sharp leading edge (LE) of the downstream MB. W-cracking has been evidenced for the first time with a very high spatial resolution infrared camera before tungsten melting was reached. These cracks develop when the monoblock temperature is about 2600 degrees C, thus higher than both ductile to brittle transition and softening threshold of tungsten, suggesting that these cracks are different from the ones observed in previous campaigns where brittle failure was involved, because of transient events on cold monoblock. Post-exposure analyses have been performed on the damaged monoblock, highlighting 12 main cracks on the LE, with a width varying from 33 mu m to 77 mu m, and an average spacing of 0.45 mm. Parallel heat flux about 90 MW/m2 has been derived from infrared temperature measurements, with a heat flux decay length on the target of 4 mm. The T-REX modelling code suggest here that with these thermal inputs, a crack can initiates due to thermal cycling without disruption, with a ductile failure, under 1 to 5 cycles for a tungsten DBTT varying from 400 degrees C to 500 degrees C.
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4.
  • Santarius, T., et al. (författare)
  • Digitalization and Sustainability : A Call for a Digital Green Deal
  • 2023
  • Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011 .- 1873-6416. ; 147, s. 11-14
  • Tidskriftsartikel (refereegranskat)abstract
    • The relation between digitalization and environmental sustainability is ambiguous. There is potential of various digital technologies to slow down the transgression of planetary boundaries. Yet resource and energy demand for digital hardware production and use of data-intensive applications is of substantial size. The world over, there is no comprehensive regulation that addresses opportunities and risks of digital technology for sustainability. In this perspective article, we call for a Digital Green Deal that includes strong, cross-sectoral green digitalization policies on all levels of governance. We argue that a Digital Green Deal should first and foremost aim at greater policy coherence: Current digital policy initiatives should include measures that service environmental goals, and environmental policies must address risks and advance opportunities of digital technologies to spur sustainability transformations.
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6.
  • Alcusa-Sáez, E. P., et al. (författare)
  • Acousto-optic interaction in polyimide coated optical fibers with flexural waves
  • 2017
  • Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 25:15, s. 17167-17173
  • Tidskriftsartikel (refereegranskat)abstract
    • Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.
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7.
  • Alcusa-Saez, E. P., et al. (författare)
  • All-fiber acousto-optic tunable filter in polyimide coated optical fibers
  • 2017
  • Ingår i: 2017 19th International Conference on Transparent Optical Networks (ICTON). - : IEEE Computer Society. - 9781538608586
  • Konferensbidrag (refereegranskat)abstract
    • We present the experimental demonstration of in-fiber acousto-optic coupling in a polyimide-coated optical fiber. Although the presence of the polyimide coating increases is significantly the attenuation of the acoustic wave, we show that acousto-optic interaction can still be produced with reasonable efficiency. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. To our knowledge, this is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.
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8.
  • Díez-Maroto, L., et al. (författare)
  • A WACS exploiting generator Excitation Boosters for power system transient stability enhancement
  • 2017
  • Ingår i: Electric power systems research. - : Elsevier Ltd. - 0378-7796 .- 1873-2046. ; 148, s. 245-253
  • Tidskriftsartikel (refereegranskat)abstract
    • Excitation Boosters (EB) are designed to improve transient stability of synchronous generators equipped with bus fed static excitation systems. They can be controlled using either local or remote signals following a disturbance. This paper explores how critical clearing times (CCT) can be improved by EBs controlled using remote signals. Particularly, Pseudo Center of Inertia (PCOI) and Dominant Interarea Path (DIP) signals derived from Phasor Measurement Units (PMU) within a Wide Area Control System (WACS) are used. Prototype controllers are tested by means of a Real Time (RT) Hardware-in-the-Loop (HIL) experimental setup.
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9.
  • Horvatovich, Peter, et al. (författare)
  • Quest for Missing Proteins : Update 2015 on Chromosome-Centric Human Proteome Project
  • 2015
  • Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 14:9, s. 3415-3431
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This paper summarizes the recent activities of the Chromosome-Centric Human Proteome Project (C-HPP) consortium, which develops new technologies to identify yet-to-be annotated proteins (termed "missing proteins") in biological samples that lack sufficient experimental evidence at the protein level for confident protein identification. The C-HPP also aims to identify new protein forms that may be caused by genetic variability, post-translational modifications, and alternative splicing. Proteogenomic data integration forms the basis of the C-HPP's activities; therefore, we have summarized some of the key approaches and their roles in the project. We present new analytical technologies that improve the chemical space and lower detection limits coupled to bioinformatics tools and some publicly available resources that can be used to improve data analysis or support the development of analytical assays. Most of this paper's content has been compiled from posters, slides, and discussions presented in the series of C-HPP workshops held during 2014. All data (posters, presentations) used are available at the C-HPP Wild (http://c-hpp.webhosting.rug.nl/) and in the Supporting Information.
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10.
  • Lange, Steffen, et al. (författare)
  • Digital Reset : Redirecting Technologies for the Deep Sustainability Transformation
  • 2023
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • Time seems out of joint. The world society has experienced a centennial pandemic, the global thermometer has displayed a sequence of hottest years on record, and Russia's war on Ukraine has shattered political order. Unsurprisingly, the economy is severely affected. Governments worldwide hope that digital technologies can provide key solutions. Yet this report shows that digitalisation, in its current and mainstream form, is rather aggravating than solving many of the pressing social and environmental crises at hand. What is needed instead is a deep sustainability transformation  that fundamentally reorganises the economy and all its sectors - agriculture, mobility, energy, buildings, industry, and consumption. The Report »Digital Reset« shows how digital technologies can support the quest for such a deep sustainability transformation. The report provides a blueprint for the European Union on how to reconceptualise digitalisation so that it first and foremost contributes to achieving carbon neutrality, resource autonomy and economic resilience while supporting equity and fully respecting citizen's rights and privacy. The report is the outcome of a two-year international science-policy dialogue, »Digitalization for Sustainability« (D4S), and presents an up-to-date comprehensive analysis of opportunities, risks and governance options regarding digitalization and sustainability.
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