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  • 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion  (33)
  • E52
  • E31
  • Astronomy
  • J24
Collection
  • 11
    Publication Date: 2019-07-13
    Description: We presented the infrared spectrum of the young binary system St 34 obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The IRS spectrum clearly shows excess dust emission, consistent with the suggestion of White & Hillenbrand that St 34 is accreting from a circumbinary disk. The disk emission of St 34 is low in comparison with the levels observed in typical T Tauri stars; silicate features at 10 and 20 microns are much weaker than typically seen in T Tauri stars; and excess emission is nearly absent at the shortest wavelengths observed. These features of the infrared spectrum suggest substantial grain growth (to eliminate silicate features) and possible settling of dust to the disk midplane (to reduce the continuum excess emission levels), along with a relatively evacuated inner disk, as expected due to gravitational perturbations by the binary system. Although the position of St 34 in the H-R diagram suggests an age of 8f Myr, assuming that it lies at the distance of the Taurus-Auriga molecular clouds, White & Hillenbrand could not detect any Li I absorption, which would indicate a Li depletion age of roughly 25 Myr or more. We suggest that St 34 is closer than the Taurus clouds by about 30-40 pc and has an age roughly consistent with Li depletion models. Such an advanced age would make St 34 the oldest known low-mass pre-main-sequence object with a dusty accretion disk. The persistence of optically thick dust emission well outside the binary orbit may indicate a failure to make giant planets that could effectively remove dust particles.
    Keywords: Astronomy
    Type: The Astrophysical Journal; 628; 2; L147 - L150
    Format: text
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  • 12
    Publication Date: 2019-07-13
    Description: We presented the results of an infrared imaging survey of Tr 37 and NGC 7160 using the IRAC and MIPS instruments on board the Spitzer Space Telescope. Our observations cover the wavelength range from 3.6 to 24 microns, allowing us to detect disk emission over a typical range of radii 0.1 to 20 AU from the central star. In Tr 37, with an age of about 4 Myr, about 48% of the low-mass stars exhibit detectable disk emission in the IRAC bands. Roughly 10% of the stars with disks may be "transition" objects, with essentially photospheric fluxes at wavelengths i 4.5 microns but with excesses at longer wavelengths, indicating an optically thin inner disk. The median optically thick disk emission in Tr 37 is lower than the corresponding median for stars in the younger Taurus region; the decrease in infrared excess is larger at 6-8 microns than at 24 microns, suggesting that grain growth and/or dust settling has proceeded faster at smaller disk radii, as expected on general theoretical grounds. Only about 4% of the low-mass stars in the 10 Myr old cluster NGC 7160 show detectable infrared disk emission. We also find evidence for 24 micron excesses around a few intermediate-mass stars, which may represent so-called "debris disk" systems. Our observations provided new constraints on disk evolution through an important age range.
    Keywords: Astronomy
    Type: The Astrophysical Journal; 638; 897-919
    Format: text
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  • 13
    Publication Date: 2019-07-13
    Description: We report the design of a new application-specific integrated circuit (ASIC) for use in radio telescope correlators. It supports the construction of correlators for an arbitrarily large number of signals. The ASIC uses an intrinsically low-power architecture along with design techniques and a process that together result in unprecedentedly low power consumption. The design is flexible in that it can support telescopes with almost any number of antennas N. It is intended for use in an "FX" correlator, where a uniform filter bank breaks each signal into separate frequency channels prior to correlation.
    Keywords: Astronomy
    Type: United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM); Jan 06, 2016 - Jan 09, 2016; Boulder, CO; United States
    Format: text
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  • 14
    Publication Date: 2019-08-26
    Description: Radio telescopes that employ arrays of many antennas are in operation, and ever larger ones are being designed and proposed. Signals from the antennas are combined by cross-correlation. While the cost of most components of the telescope is proportional to the number of antennas N, the cost and power consumption of cross-correlationare proportional to N2 and dominate at sufficiently large N. Here we report the design of an integrated circuit (IC) that performs digital cross-correlations for arbitrarily many antennas in a power-efficient way. It uses an intrinsically low-power architecture in which the movement of data between devices is minimized. In a large system, each IC performs correlations for all pairs of antennas but for a portion of the telescope's bandwidth (the so-called "FX" structure). In our design, the correlations are performed in an array of 4096 complex multiply-accumulate (CMAC) units. This is sufficient to perform all correlations in parallel for 64 signals (N=32 antennas with 2 opposite-polarization signals per antenna). When N is larger, the input data are buffered in an on-chipmemory and the CMACs are re-used as many times as needed to compute all correlations. The design has been synthesized and simulated so as to obtain accurate estimates of the IC's size and power consumption. It isintended for fabrication in a 32 nm silicon-on-insulator process, where it will require less than 12mm2 of silicon area and achieve an energy efficiency of 1.76 to 3.3 pJ per CMAC operation, depending on the number of antennas. Operation has been analyzed in detail up to N = 4096. The system-level energy efficiency, including board-levelI/O, power supplies, and controls, is expected to be 5 to 7 pJ per CMAC operation. Existing correlators for the JVLA (N = 32) and ALMA (N = 64) telescopes achieve about 5000 pJ and 1000 pJ respectively usingapplication-specific ICs in older technologies. To our knowledge, the largest-N existing correlator is LEDA atN = 256; it uses GPUs built in 28 nm technology and achieves about 1000 pJ. Correlators being designed for the SKA telescopes (N = 128 and N = 512) using FPGAs in 16nm technology are predicted to achieve about 100 pJ.
    Keywords: Astronomy
    Type: Journal of Astronomical Instrumentation; 5; 2; 1650002
    Format: text
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  • 15
    Publication Date: 2019-07-13
    Description: The architecture of a cross-correlator for a synthesis radio telescope with N greater than 1000 antennas is studied with the objective of minimizing power consumption. It is found that the optimum architecture minimizes memory operations, and this implies preference for a matrix structure over a pipeline structure and avoiding the use of memory banks as accumulation registers when sharing multiply-accumulators among baselines. A straw-man design for N = 2000 and bandwidth of 1 GHz, based on ASICs fabricated in a 90 nm CMOS process, is presented. The cross-correlator proper (excluding per-antenna processing) is estimated to consume less than 35 kW.
    Keywords: Astronomy
    Type: 2011 URSI General Assembly and Scientific Symposium; Aug 13, 2011 - Aug 20, 2011; Istanbul; Turkey
    Format: text
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  • 16
    Publication Date: 2020-12-15
    Description: Negli ultimi anni il concetto di vulnerabilità sismica è tristemente entrato a far parte delle conoscenze anche dei non addetti ai lavori. Infatti, gli eventi sismici che hanno interessato dagli inizi del ‘900 il territorio Italiano, hanno sistematicamente messo in risalto l’elevata vulnerabilità sismica del nostro patrimonio edilizio, ivi compresi i beni monumentali, nonché, l’inesistenza di qualsiasi attività di programmazione della manutenzione periodica ordinaria e straordinaria delle strutture sismo-resistenti, che garantiscono nel tempo la conservazione delle loro capacità di risposta alle perturbazioni esterne.Il progetto PON sul Monitoraggio in Area Sismica di SIstemi MOnumentali nasce con la prerogativa di produrre uno strumento dedicato alla tutela di strutture a valenza storico – artistica, attraverso un percorso di catalogazione, di analisi del bene inteso come elemento costituito da elementi resistenti e da materiali, di studio del sito dove la struttura è ubicata e di attività di monitoraggio.
    Description: PON 01/02710 MASSIMO - Monitoraggio in Area SiSmica di benI MOnumentali
    Description: Published
    Description: 41-51
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5T. Sorveglianza sismica e operatività post-terremoto
    Description: N/A or not JCR
    Description: open
    Keywords: beni monumentali ; tecniche NDT ; monitoraggio ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 17
    Publication Date: 2020-11-16
    Description: Geological, geophysical and geotechnical investigations, for the characterization of the strong-motion recording sitesmanaged by the ItalianCivil Protection, have been carried out in the framework of the project “Italian strong-motion database in the period 1972–2004”. The project aimed at creating an updated database of strong-motion data acquired in Italy by different institutions in the time span 1972–2004, and at improving the quality of disseminated data. This article illustrates the state of the recording site characterization before the beginning of the project, explains the criteria adopted to select the sites where geophysical/ geotechnical investigation have been performed and describes the results of the promoted field surveys.
    Description: Published
    Description: 1189–1207
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: site ; characterization ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 18
    Publication Date: 2020-11-30
    Description: Taking advantage of a large displacement-release experiment on a twostory reinforced concrete building located in Bagnoli (Naples, Italy), we performed free-field measurements using 3D seismometers, accelerometers, and a 100-m-long vertical array. The ground motion was noticeable: near the building, the acceleration exceeded 5% g. At each measurement point, it was possible to recognize two source terms, due to the tested building and to the reaction structure. The two sources generated different wave trains. High-frequency accelerations propagated as Rayleigh waves, whereas 1–2 Hz waves carrying most of the displacement propagated only as body waves. The experiment lends further support to the hypothesis that buildings are able to modify substantially the free-field ground motion in their proximity: the peak ground acceleration we observed is the 20% of the ground acceleration required to produce a displacement on the building equal to the one imposed during the release test. We recognize, however, the difficulty of a realistic modeling of wave propagation in the topmost layer of a densely urbanized area.
    Description: Published
    Description: 2457–2464
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: Seismic Source ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 19
    Publication Date: 2017-04-04
    Description: EC Project EVG1-CT-2002-00069 RELIEF Project Partner 2: Istituto Nazionale di Geofisica e Vulcanologia, Roma, ITALY
    Description: Unpublished
    Description: open
    Keywords: North Anatolian Fault ; Earthquake faulting ; Seismic Hazard Assessment ; Turkey ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
    Format: 4384582 bytes
    Format: application/pdf
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  • 20
    Publication Date: 2017-04-04
    Description: Progetto INGV-DPC S3 “Scenari di scuotimento in aree di interesse prioritario e/o strategico”
    Description: Published
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: open
    Keywords: scenario di scuotimento ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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