Search results for "Vela"

“Study of Pulsar Light Curves by Cluster Analysis”

1986

The distribution of the phase numbers, corresponding to the arrival times of the gamma-ray photons detected by the COS-B satellite from the directions of the Crab and Vela pulsars, is analyzed by a clustering technique with the aim to detect possible microstructures in the pulsed emission. The method is found to be promising especially in view of the future gamma-ray experiments where better photon counting statistics is expected.

The FIGARO II experiment: a general outline of the mission and the principal scientific results

1992

The FIGARO II (French Italian Gamma-Ray Observatory) experiment has been launched successfully three times: in July 1986 from Milo (Trapani), in November 1988 from Charleville (Australia) and in July 1990 again from Milo. In the first flight the observational program was limited to the Crab pulsar PSR0531+21 only because of a telemetry failure: the high sensitivity of FIGARO II allowed an accurate study of the pulse shape as well as a phase-resolved spectroscopy. It was also possible to evaluate the dispersion measure of the Crab pulsar at the flight date from the time delay between gamma-ray and radio pulses. The major results of the second flight were a stringent upper limit to the low-en…

Hydrodynamic simulations of the interaction of supernova shock waves with a clumpy environment: the case of the RX J0852.0-4622 (Vela Jr.) supernova …

2013

Observations in all electromagnetic bands show that many supernova remnants (SNRs) have a very aspherical shape. This can be the result of asymmetries in the supernova explosion or a clumpy circumstellar medium. We study the generation of inhomogeneities and the mixing of elements arising from these two sources in multidimensional hydrodynamic simulations of the propagation of a supernova blast wave into a cloudy environment. We model a specific SNR, Vela Jr (RX J0852.0-4622). By comparing our results with recent observations, we can constrain the properties of the explosion. We find that a very energetic explosion of several 10^{51} erg occurring roughly about 800 years ago is consistent w…

Hydrodynamic modelling of ejecta shrapnel in the Vela supernova remnant

2013

Many supernova remnants (SNRs) are characterized by a knotty ejecta structure. The Vela SNR is an excellent example of remnant in which detached clumps of ejecta are visible as X-ray emitting bullets that have been observed and studied in great detail. We aim at modelling the evolution of ejecta shrapnel in the Vela SNR, investigating the role of their initial parameters (position and density) and addressing the effects of thermal conduction and radiative losses. We performed a set of 2-D hydrodynamic simulations describing the evolution of a density inhomogeneity in the ejecta profile. We explored different initial setups. We found that the final position of the shrapnel is very sensitive …

Tommaso Stanislao Velasti tra filellenismo partenopeo e ideologia “albanista”

2021

L'opera del gesuita greco originario di Scio, Tommaso Stanislao Velasti, costituisce un compendio dell'ideologia filoellenica che a partire dalla seconda metà del XVIII secolo, influenzò i processi irredentistici che nel 1821 portarono la Grecia a proclamare la propria indipendenza dalla Sublime Porta. Nel suo percorso di ricerca, Velasti ebbe la fortuna di incontrare le opere di intellettuali albanesi di Sicilia, presso il cui seminario palermitano ebbe modo di dimorare negli anni cruciali della sua svolta ideologica. Lo studio di alcuni fondamentali documenti emersi dall'archivio del Seminario fondato da p. Giorgio Guzzetta ha evidenziato la filiazione di idee fondamentali dell'ideologia …

Le Puy-en-Velay (43) Baptistère Saint-Jean - Etude des liants de maçonnerie

2008

RIVELATORI PER RADIAZIONE X IN TECNOLOGIA PLANARE

2012

Instruccion que enseña el fin y metodo del instituto de la Real Congregacion del Alumbrado, y Vela al Santísimo Sacramento quando está reservado en l…

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Study of economic availability related to rare metals in the context of the energy transition

2014

A growing number of academic studies and international organizations reports have noticed an increasing dependency of new energy technologies on a specific class of natural resources often called minor metals. For several years, worries about economic availability of these metals in order to realize the energy transition have appeared. This thesis aims at underline the broader risks and constraints involved by general use of these metals in new energy technologies. A first part of this thesis is devoted to theories and indicators related to the depletion of non renewable resources. This part also shows that minor metals share many characteristics and that they can form a group of metal cons…

The risk management in the international contracts of marine renewable energy : focus on offshore wind farms

2022

At a time when climate change is becoming the main concern, the renewable energy sector is developing extremely rapidly. In order to add other sources to the existing ones and to increase electricity production while ensuring its stability, the sea has quickly been considered as an attractive alternative. However, the creation of a new industry is a major challenge and marine renewable energy projects are very expensive and risky. The concept of risk was created specifically regarding the management of human activities at sea. The example of offshore wind energy allows us to go back to the origins of the notion of risk by considering it from the point of view of the company, and to analyse …