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31.
Cesare Barbieri 《Experimental Astronomy》1997,7(4):257-279
The main features of the 3.5m Telescopio Nazionale GALILEO (TNG) have been derived from those of the ESO NTT, although with modifications in several areas, as described e.g. in Barbieri et al., 1994. The site of the TNG is the Observatorio del Roque de los Muchachos, in the Canary Island of La Palma. Construction activities, started in 1993, are nearing completion. The telescope structure, after testing in the Ansaldo factory near Milano, has been disassembled and is gradually being transported and installed on site, in parallel with the rotating dome. The three main mirrors, figured by ZEISS, will be transported in spring '96 to the WHT plant at the Roque for aluminisation before installation on the telescope.Three major subsystems still undergo intensive activity in Italy, namely testing of the M2 and M3 units, testing of the operational version of the control hardware and software, and construction of the two Rotator Adapters (R/A) for the Nasmyth foci.First light instruments are also being built. Nasmyth Arm A is reserved for the imaging section, composed by a visual camera, a near-IR camera, plus a common adaptive optics module. On arm B, a faint object spectrograph with long slit, atmospheric dispersion corrector, multiobject and imaging capabilities, will be mounted. A fixed high resolution spectrograph with optical derotation is also being designed.Attention has already been given to the archive of the data.It is planned to have first light at the end of 1996, and to start regular scientific operations after an adequate period of debugging and commissioning. 相似文献
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33.
Cesare Emiliani Eric B. Kraus Eugene M. Shoemaker 《Earth and Planetary Science Letters》1981,55(3):317-334
A paleoecological analysis of the fossil record before and after the Cretaceous/Tertiary boundary indicates that the widespread extinctions and biological stresses around the boundary are best explained in terms of a sudden, significant, but short temperature rise. L. Alvarez and co-authors, having found an enrichment in iridium at the same boundary, postulated that it was associated with the impact of an extraterrestrial body. If this body struck the ocean, the water injected into the atmosphere may have led to a transient increase in the global surface temperature. This temperature pulse may have been primarily responsible for the effects observed in the biosphere. The pattern of extinction of higher plant species suggests that splash down occurred in the northern Pacific-Bering Sea area. 相似文献
34.
Domenico Antonio De Luca Cesare Comina Manuela Lasagna Enrico Destefanis Luciano Masciocco Alberto Godio Stefano Stocco 《Environmental Earth Sciences》2018,77(1):19
Aquifer overexploitation is a common problem in drinking water management. This will become more and more important given the general reduction of water resources. To overcome overexploitation, one of the most adopted solutions is the relocation of extraction wells. To establish the positions of new wells, a precise knowledge of the hydrogeological setting is required. Specific surveys are therefore necessary to obtain information over wide investigation zones. Geophysical methods, particularly electromagnetic and electrical, can be useful with this aim. In the present paper a case history on the combined use of Electric Resistivity Tomography and Time Domain Electromagnetic soundings is reported. Surveys have been performed within the Maggiore and Traversola Valleys, to investigate the uppermost part of the Quaternary deposits, hosting the near surface aquifer. The electromagnetic data have been inverted with a spatially constrained approach by assuming a quasi 1D model of the subsurface. Geophysical surveys allowed for depicting the depth and lateral continuity of the supposed aquifer level in the surveyed area up to a depth of about 200 m and proposing potential positions for well relocation. 相似文献
35.
Antonio Di Cesare Felice Carlo Ponzo Domenico Nigro 《Bulletin of Earthquake Engineering》2014,12(6):2777-2796
The advantages of passive supplemental dampers for performance enhancement of new and existing structures have been demonstrated extensively in the past. The big amount of experimental tests carried out all over the world on framed structures upgraded by energy dissipating bracing (EDB) systems based on hysteretic dampers (HDs), have shown their effectiveness in reducing seismic effects on buildings. The mechanical characteristics of the HDs in some cases may be different from those arising by the design procedure due to industrial tolerance or because of some damage suffered during previous earthquakes. In order to assess the robustness of this technique, in terms of capacity of seismic vibrations control even for significant changes in the mechanical characteristics of the EDB system respect to the design ones, in this paper experimental tests and parametric nonlinear time history analysis have been carried out changing the characteristics of the HD stiffness and strength. The experimental results refer to the shaking table tests performed at the Structural Laboratory of the University of Basilicata within a wide research program, named Joint Experimental Testing on Passive and semiActive Control Systems. The program has been completely funded by the Italian Department of Civil Protection within the activity of the Research Line 7 of the ReLUIS (Italian Network of University Laboratories of Earthquake Engineering) 2005–2008 project. A displacement-focused design procedure has been considered to evaluate the mechanical characteristics of the dissipating system, with the aim of limiting inter-storey drifts after frame yielding. From the experimental point of view, two design solutions have been tested for chevron braces equipped with HD, assuming the same stiffness but different values of both ductility demand and yield strength of the HDs. Moreover, parametric studies have been performed through numerical simulations. This paper provides an overview of the experimental set up and briefly summarizes the experimental outcomes and the comparison with the results of numerical nonlinear time history analysis. Moreover, the results of the parametric analysis for the assessment of the performances of the dissipating system in controlling structural response are presented. 相似文献
36.
Manzini Federico Crippa Roberto Oldani Virgino Guaita Cesare 《Earth, Moon, and Planets》1999,87(2):73-85
Using a CCD camera attached to the 0.335 m and 0.20 m reflectors of S.A.S. Observatory (Novara, Italy), we followed the linear
jets and shells of comet Hale–Bopp between May 1996 and May 1997. In addition to confirming the model of Sekanina and Bohenhardt
(1997), the study of the linear jets provided indications concerning the orientation of the comet's axis of rotation over
time. The study of the shells revealed that the speed at which they move away from the nucleus was not constant. A periodic
variation of the shell expansion velocity may not be excluded : if so, a possible precessional effect on the axis of rotation
of the comet's nucleus could explain this behavior.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
37.
Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta
Horst Uwe Keller Sonia Fornasier Stubbe F. Hviid Jörg Knollenberg Miriam Rengel Gabriele Cremonese Detlef Koschny Ekkehard Kührt Holger Sierks Cesare Barbieri Hans Rickman Michael F. A'Hearn Maria-Antonella Barucci Vania da Deppo Björn J.R. Davidsson Stefano Debei Fritz Gliem José J. Lopez Moreno Giampiero Naletto Angel Sanz Andrés 《Icarus》2007,187(1):87-103
The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impact projectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showed regular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness of Tempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structures were created by the impact. Most of the material moved with . Much of it left the comet in the form of icy grains which sublimated and fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet ( of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions with gas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations of the density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain. 相似文献
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39.
P. Prof. Dr. P. Cesare Coppedé 《Pure and Applied Geophysics》1947,10(1-2):11-20
Riassunto Si rendono note le condizioni e le attività attuali dell'Osservatorio; si espongono, mediante alcune tabelle, i principali valori meteoricinormali e si confrontano coi rispettivi valorimedi del 1946; infine si enumerano e si classificano i terremoti registrati nell'ultimo anno.
Summary We take care to notify the present conditions and activity of the Observatory. We are showing through some prospects the chief meteorologicalnormal values, confronting them with the respective middle values of the year 1946. At the end we give a statistical sketch of the earthquakes registered during the last year.
Résumé On fait connaître les conditions et les activités actuelles de l'Observatoire; on expose, par moyen de prospects, les principales valeurs météoriquesnormales et on les confronte avec les valeursmoyennes corréspondantes de l'année 1946; enfin on énumère et on classifie les tremblements de terre enrégistrés pendant la dernière année.相似文献
40.