87,753 research outputs found
Data Archiving and Distribution of the Virgo Antenna for Gravitational Wave Detection
No full textWe describe the architecture of the data archiving and distribution of the Virgo antenna for gravitational wave detection. The main characteristic of this system is the modularity of the architecture. This solution allows system upgrades without dramatic changes of the hardware and software components. The main performances are: 1. Maximum sustained data flow of 10 Mbyte/s on DLT tapes (35/70 Gbyte) for the raw data archiving; 2. Up to 1 Tbyte data archiving capacity on disk at a maximum sustained data flow of 25 Mbyte/s for the online data distribution; 3. Up to 10 Mbyte/s data retrieval flow for the on-line data distribution. The basic architecture of the system consists of two sections: an acquisition and storage section and a data management section. The former is a LynxOS based system with the disks directly connected to the CPU slave boards, the latter is a DEC-Unix Alpha Server (Data Server), NFS mounting the LynxOS disks through a Fast Ethernet networ
The search for Gravitational Waves: Status and perspectives
No full textIn this paper we give an overview of the present status and future perspectives of the search for gravitational waves. Gravitational Waves (GW) are predicted by the General Theory of the Relativity and, due to their very weak interaction with matter, can be an invaluable tool to look to the universe up to its very first moments. On the other hand, these same characteristics make their detection very difficult to achieve, and, at present, we have only indirect proof of their existence. In the last years the techniques adopted to directly detect GWs converged to laser interferometers. A world network of kilometer-scale laser interferometers is presently taking data but their sensitivity does not seem enough to give results in reasonable times. To this purpose all the presently working interferometers have plans to enhancement in the next few years and second-generation detectors, both ground and space based, are already in the design phase
The protoplanetary disk of FT Tauri : multi-wavelength data analysis and modeling
No full textThis work is supported by the Swiss National Science Foundation. L.P. acknowledges the funding from the FP7 Intra-European Marie Curie Fellowship (PIEF-GA-2009-253896). L.P. has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n. 267251. I.K., W.F.T., F.M., and P.W. acknowledge funding from an NWO MEERVOUD grant and from the EU FP7- 2011 under Grant Agreement nr. 284405. F.M. acknowledges support from the Millennium Science Initiative (Chilean Ministry of Economy), through grant Nucleus P10-022-F. I. Pascucci acknowledges NASA/ADP Grant NNX10AD62G.Investigating the evolution of protoplanetary disks is crucial for our understanding of star and planet formation. Several theoretical and observational studies have been performed in the last decades to advance this knowledge. FT Tauri is a young star in the Taurus star forming region that was included in a number of spectroscopic and photometric surveys. We investigate the properties of the star, the circumstellar disk, and the accretion and ejection processes and propose a consistent gas and dust model also as a reference for future observational studies. We performed a multi-wavelength data analysis to derive the basic stellar and disk properties, as well as mass accretion/outflow rate from TNG-Dolores, WHT-Liris, NOT-Notcam, Keck-Nirspec, and Herschel-Pacs spectra. From the literature, we compiled a complete Spectral Energy Distribution. We then performed detailed disk modeling using the MCFOST and ProDiMo codes. Multi-wavelengths spectroscopic and photometric measurements were compared with the reddened predictions of the codes in order to constrain the disk properties. This object can serve as a benchmark for primordial disks with significant mass accretion rate, high gas content and typical size.Peer reviewe
Restauri, controlli in preventivo e in corso d’opera: la funzione delle indagini diagnostiche. Il rilievo del colore
No full textIl settore della diagnostica, alla luce del progresso scientifico-tecnologico, ha visto negli ultimi anni un'implementazione progressiva dei metodi e delle tecniche di indagine sul patrimonio storico-architettonico, parallelamente all'accrescimento della sensibilità nei confronti della salvaguardia e della valorizzazione di un patrimonio che, per naturale caducità della materia o superficialità di valutazione negli interventi, presenta diffusi rischi di perdita. L'approccio diagnostico al tema del colore, che presuppone il doveroso interrogativo circa una possibile "definizione" di colore, può consentire di effettuare varie e affidabili indagini non distruttive, sia di tipo qualitativo che quantitativo, estremamente utili nel processo conservativo
A Michelson interferometer for seismic wave measurement: theoretical analysis and system performances
No full textAbstract
This papers describes a new low-frequency seismic sensor for geophysical applications. The instrument is basically a monolithic tunable folded pendulum with an interferometric readout system, that can be configured as seismometer or as accelerometer. The monolithic mechanical design and the introduction of a laser interferometric technique for the readout implementation make it a very sensitive and compact instrument with a very good immunity to environmental noises. Preliminary tests on the mechanical performances of the monolithic structure and on the optical reaodut have been performed. Interesting result is the measured resonant frequency of the instrument of ≈ 150 mHz obtained with a rough tuning, demonstrating the feasibility of a resonant frequency of the order of 5 mHz with a more refined tuning. The mechanics of the seismic sensor, the optical scheme of the readout system, the theoretical predictions and the preliminary experimental performances as seismometer are discussed in detail, together with the foreseen further improvements
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