28 research outputs found

    HKT manifolds: Hodge theory, formality and balanced metrics

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    Let (M,I,J,K,Ω)(M,I,J,K,\Omega) be a compact HKT manifold and denote with \partial the conjugate Dolbeault operator with respect to II, J:=J1J\partial_J:=J^{-1}\overline\partial J, Λ:=[,Λ]\partial^\Lambda:=[\partial,\Lambda] where Λ\Lambda is the adjoint of L:=ΩL:=\Omega\wedge-. Under suitable assumptions, we study Hodge theory for the complexes (A,0,,J)(A^{\bullet,0},\partial,\partial_J) and (A,0,,Λ)(A^{\bullet,0},\partial,\partial^\Lambda) showing a similar behavior to K\"ahler manifolds. In particular, several relations among the Laplacians, the spaces of harmonic forms and the associated cohomology groups, together with Hard Lefschetz properties, are proved. Moreover, we show that for a compact HKT SL(n,H)\mathrm{SL}(n,\mathbb{H})-manifold the differential graded algebra (A,0,)(A^{\bullet,0},\partial) is formal and this will lead to an obstruction for the existence of an HKT SL(n,H)\mathrm{SL}(n,\mathbb{H})-structure (I,J,K,Ω)(I,J,K,\Omega) on a compact complex manifold (M,I)(M,I). Finally, balanced HKT structures on solvmanifolds are studied.Comment: 17 pages. Comments are welcom

    Adjoint Monte Carlo Simulation of Fusion Product Activation Probe Experiment in ASDEX Upgrade tokamak

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    The activation probe is a robust tool to measure flux of fusion products from a magnetically confined plasma. A carefully chosen solid sample is exposed to the flux, and the impinging ions transmute the material making it radioactive. Ultra-low level gamma-ray spectroscopy is used post mortem to measure the activity and, thus, the number of fusion products. This contribution presents the numerical analysis of the first measurement in the ASDEX Upgrade tokamak, which was also the first experiment to measure a single discharge. The ASCOT suite of codes was used to perform adjoint/reverse Monte Carlo calculations of the fusion products. The analysis facilitates, for the first time, a comparison of numerical and experimental values for absolutely calibrated flux. The results agree to within a factor of about two, which can be considered a quite good result considering the fact that all features of the plasma cannot be accounted in the simulations. Also an alternative to the present probe orientation was studied. The results suggest that a better optimized orientation could measure the flux from a significantly larger part of the plasma.Comment: Contribution in 1st EPS Conference on Plasma Diagnostics. First two versions are for PoS(ECPD 2015)055. This 3rd version was accepted for publishing in Journal of Instrumentatio

    Complex Symplectic Lie Algebras with Large Abelian Subalgebras

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    We present two constructions of complex symplectic structures on Lie algebras with large abelian ideals. In particular, we completely classify complex symplectic structures on almost abelian Lie algebras. By considering compact quotients of their corresponding connected, simply connected Lie groups we obtain many examples of complex symplectic manifolds which do not carry (hyper)k\"ahler metrics. We also produce examples of compact complex symplectic manifolds endowed with a fibration whose fibers are Lagrangian tori.Comment: 33 pages, no figures. Comments are welcome

    Third harmonic ICRF heating of Deuterium beam ions on ASDEX Upgrade

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    We report on recent experiments on the ASDEX Upgrade (AUG) tokamak (major radius R ≈1.65 m, minor radius a ≈ 0.5 m) with third harmonic ICRF heating of deuterium beam ions. Prior to this work, the scheme has been developed and applied on the JET tokamak, the largest currently operating tokamak (R ≈ 3 m, a ≈ 1 m), for fusion product studies and for testing alpha particle diagnostics in preparation of ITER [1]. The experiments reported here demonstrate that this scheme can also be used in medium size tokamaks such as AUG despite their reduced fast ion confinement.This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.Postprint (published version

    Bollettino Sismico Italiano: Analisys of Early Aftershocks of the 2016 MW 6.0 Amatrice, MW 5.9 Visso and MW 6.5 Norcia earthquakes in Central Italy

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    The Amatrice-Visso-Norcia seismic sequence is the most important of the last 30 years in Italy. The seismic sequence started on 24 August, 2016 and still is ongoing in central Apennines. At the end of February 2017 more than 57,000 events were located, 80,000 events up to the end of September 2017 (Fig. 1). The mainshocks of the sequence occurred on 24 August 2016 (Mw 6.0 and Mw 5.4), 26 October 2016 (Mw 5.4 and Mw 5.9), 30 October 2016 (Mw 6.5), 18 January 2017 (four earthquakes Mw≥ 5.0). In this seismic sequence, all the waveforms recorded by temporary stations deployed by the SISMIKO emergency group (stations T12**; Moretti et al., 2016) where available in real- time at the surveillance room of INGV. Because of the high level of seismicity and the dense seismic network installed in the region, more than 150 events per day were located at the end of February 2017; still 60 events per day were located up to the end of August 2017.The Amatrice-Visso-Norcia is the most important seismic sequence since 2015, the time when the analysis procedures of the BSI group (Bollettino Sismico Italiano) were revised (Nardi et al., 2015). BSI is now available every four months on the web: bulletins contain revised earthquakes (location and magnitude) with ML≥ 1.5, quasi-real time revision of ML≥ 3.5 earthquakes and phase arrivals from waveforms recorded on seismic stations available from the European Integrated Data Archive (EIDA), (Mazza et al., 2012). These last procedures allow the integration of signals from temporary seismic stations (Moretti et al., 2014) installed by the emergency group SISMIKO (Moretti and Sismiko working group, 2016), even when they are not in real time transmission, if they are rapidly archived in EIDA, together with real time signals from the seismic stations of the permanent INGV network. The analysis strategy of the BSI group for the Amatrice -Visso - Norcia seismic sequence (AVN.s.s in the following) was to select the earthquakes located in the box with min/max latitude: 42.2/43.2 - and min/max longitude: 12.4/14.1 to prepare a special volume of BSI on the seismic sequence.PublishedTrieste, Italy1SR. TERREMOTI - Servizi e ricerca per la Societ

    RAPPORTO BOLLETTINO SISMICO ITALIANO sulla revisione dei giorni 24-26 agosto; 26-27 ottobre; 30 ottobre-1 novembre 2016

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    La sequenza sismica Amatrice-Visso-Norcia (AVN s.s. nel seguito) include il terremoto più forte avvenuto negli ultimi 30 anni in Italia ed è caratterizzata da molteplici eventi di magnitudo superiore a 5.0. La sequenza sismica è iniziata il 24 agosto 2016 con due terremoti di Mw 6.0 e Mw 5.4 nella zona di Amatrice (RI) ed è proseguita con altri due terremoti forti avvenuti il 26 ottobre, Mw 5.4 e Mw 5.9 nell’area compresa tra i comuni di Visso (MC), Castel S.Angelo sul Nera (MC), Norcia (PG) e Arquata del Tronto (AP). Il 30 ottobre si è verificato l’evento più forte della sequenza (Mw 6.5), con epicentro non lontano da Norcia, che ha colpito un vasto settore dell'Italia centrale, interessando ben quattro regioni (Umbria, Marche, Lazio e Abruzzo).Istituto Nazionale di Geofisica e VulcanologiaUnpublished1SR. TERREMOTI - Servizi e ricerca per la Societ

    Bollettino Sismico Italiano settembre – dicembre 2017

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    I parametri dei terremoti registrati dalla Rete Sismica Nazionale Italiana, localizzati nelle sale di monitoraggio di Roma, di Napoli e di Catania sono immediatamente disponibili sul web, alla pagina http://terremoti.ingv.it/, e nell’Italian Seismological Instrumental and parametric Data-base (ISIDe working group (2016) version 1.0, DOI: 10.13127/ISIDe). Gli analisti del Bollettino Sismico Italiano (BSI) ricontrollano i parametri dei terremoti calcolati, inserendo pesi e polarità degli arrivi delle onde sismiche e integrando, inoltre, i dati letti in sala con tutti quelli disponibili nel sistema di acquisizione. Dal 1985 i dati del bollettino sono consultabili nel data-base ISIDe.Istituto Nazionale di Geofisica e Vulcanologia - Dipartimento di Protezione CivilePublished4IT. Banche dat
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