排序方式： 共有36条查询结果，搜索用时 15 毫秒
11.
Mauskopf PD Ade PA de Bernardis P Bock JJ Borrill J Boscaleri A Crill BP DeGasperis G De Troia G Farese P Ferreira PG Ganga K Giacometti M Hanany S Hristov VV Iacoangeli A Jaffe AH Lange AE Lee AT Masi S Melchiorri A Melchiorri F Miglio L Montroy T Netterfield CB Pascale E Piacentini F Richards PL Romeo G Ruhl JE Scannapieco E Scaramuzzi F Stompor R Vittorio N 《The Astrophysical journal》2000,536(2):L59-L62
We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 μK(CMB). 相似文献
12.
Gianluca Masi 《Icarus》2003,163(2):389-397
The likely existence of bodies orbiting the Sun with aphelia Q < 0.983 AU has been suggested by numerical simulations of the dynamical evolution of the near-Earth objects (NEOs) population. For obvious reasons, these hypothetical minor bodies are called inner-Earth objects (IEOs). While much progresses has been made in learning more about the Amor, Apollo, and Aten population from surveys optimized for their discovery, no large, systematic, and similar observation projects devoted to the search of IEOs have been started. For their own orbital nature, IEOs can be observed only at small solar elongations (<90°), corresponding to regions of the sky currently neglected by the modern, ongoing surveys. This paper discusses a possible ground-based approach to look for IEOs, providing some useful tricks and the results of simulated surveys devoted to their discovery. It will be shown that such a search promises interesting results, the setup of a dedicated project being highly recommended. 相似文献
13.
J-Ph. Bernard P. Ade Y. André J. Aumont L. Bautista N. Bray P. de Bernardis O. Boulade F. Bousquet M. Bouzit V. Buttice A. Caillat M. Charra M. Chaigneau B. Crane J.-P. Crussaire F. Douchin E. Doumayrou J.-P. Dubois C. Engel P. Etcheto P. Gélot M. Griffin G. Foenard S. Grabarnik P. Hargrave A. Hughes R. Laureijs Y. Lepennec B. Leriche Y. Longval S. Maestre B. Maffei J. Martignac C. Marty W. Marty S. Masi F. Mirc R. Misawa J. Montel L. Montier B. Mot J. Narbonne J-M. Nicot F. Pajot G. Parot E. Pérot J. Pimentao G. Pisano N. Ponthieu I. Ristorcelli L. Rodriguez G. Roudil M. Salatino G. Savini O. Simonella M. Saccoccio P. Tapie J. Tauber J.-P. Torre C. Tucker 《Experimental Astronomy》2016,42(2):199-227
Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project, which aims at characterizing one of these foreground sources, the polarized continuum emission by dust in the diffuse interstellar medium. The PILOT experiment also constitutes a test-bed for using multiplexed bolometer arrays for polarization measurements. This paper presents the instrument and its expected performances. Performance measured during ground calibrations of the instrument and in flight will be described in a forthcoming paper. 相似文献
14.
Experimental and numerical evaluation of the fundamental period of undamaged and damaged RC framed buildings 总被引：1，自引：1，他引：0
This paper deals with the period evaluation of Reinforced Concrete (RC) framed buildings in elastic, yield and severely damaged states. Firstly, period-height relationships either reported in the literature, or obtained from both numerical simulations (eigenvalue analyses) and experimental measurements (ambient vibration analyses) have been examined and compared. Structural types representing low-rise, mid-rise and high-rise RC buildings without earthquake resistant design, widely present in the Italian and European built environment, have been studied. Results have shown high differences between numerical and experimental period values. Period elongation (stiffness degradation) during and after strong ground shaking has been also examined based on results from experimental in situ and laboratory tests performed on some RC framed building structures which suffered moderate-heavy damage. Some comments on the relationship between damage level and period elongation are reported. 相似文献
15.
The Alburni massif (1742m a.s.l.) stretches NW–SE, about 23km long and 9–10km wide, covering 246km2 with an average elevation of about 940m a.s.l. This massif, with more than 500 caves, is the most important karst area in southern Italy. The karst channel network is hierarchically organized: some channels feed a major spring (1m3/s) with a very short transit time while others communicate directly with the basal water table related to other springs (Q > 3m3/s).There are several dolines and swallow holes just above the basal water table and in the urbanized areas; for years a swallow hole directly transferred pollutants into the aquifer. The contamination vulnerability map shows that the prevalent vulnerability degree ranges from high to very high, due to the widespread karstification of the area and to the presence, on the plateau, of large vegetated areas with gentle slopes favouring fast infiltration.Hence it is important to ascertain the human impact on the area and the consequent contamination risk of the aquifer of the Alburni karst area. Three main layers were created to assess groundwater contamination risk: the vulnerability map, the hazard map, and the value map.The groundwater contamination risk map stresses the importance in a park area of aquifer vulnerability, which strongly influences the risk: indeed, the prevalent moderate degree of risk in the final map depends on the high vulnerability and the low hazard degree. However, in the future it is crucial to take into account the nature of the agricultural land use allowed in the park, which could increase the hazard degree and consequently the risk degree. 相似文献
16.
The fluorite-bearing hydrothermal mineralization in Sardinia mainly occurs within Paleozoic volcanic and metasedimentary rocks. Only 3 occurrences are located in volcanic and siliciclastic Cenozoic rocks. Most Sardinian fluorites exhibit relatively high rare earth and Y (REY) contents, strong positive Y anomalies, slightly negative Ce and generally positive Eu anomalies. These features indicate that the REY were mobilized mainly from non-carbonate rocks. Neither Sr nor Nd isotopes can be used to date radiometrically the Sardinian fluorites. However, the measured Sr-isotope ratios of the fluorites hosted by Paleozoic rocks fit mixing lines in the 1000/Sr versus 87Sr/86Sr plot once recalculated at 280 Ma, suggesting that the age inferred for the correction probably represents that of the formation of the fluorite mineralization. Mixing likely occurred between diluted surficial waters and brines circulating mainly through the Lower Paleozoic metasedimentary basement. The Cenozoic fluorites exhibit chemical and isotopic features similar to those of the Paleozoic fluorites, except the Nuraghe Onigu fluorite displaying a possible contribution of Sr from Cenozoic magmatic rocks. The initial εNd values of the Paleozoic fluorites fit the age proposed for the formation of the deposits. Moreover, the values suggest that radiogenic Nd was provided to the fluids from the Ordovician siliciclastic basement, except for 3 deposits where the potential source rocks of Nd were mainly Ordovician acidic magmatic rocks. The initial εNd values of the Cenozoic fluorites suggest a provenance of Nd essentially from the leaching of Variscan granitoids. 相似文献
17.
Peak and integral seismic parameters of L��Aquila 2009 ground motions: observed versus code provision values 总被引：1，自引：1，他引：0
A. Masi L. Chiauzzi F. Braga M. Mucciarelli M. Vona R. Ditommaso 《Bulletin of Earthquake Engineering》2011,9(1):139-156
The M
w 6.3 L’Aquila earthquake of April 6, 2009 hit a wide area of the Abruzzo region (Central Italy). The epicentre of the main
shock was very close to the urban centre of L’Aquila, the regional capital, with an epicentral distance less than 10 km. It
was the strongest earthquake ever recorded in Italy which has provided ground motion recordings from accelerometric stations
located in close proximity to the epicentre. Because of this, several remarkable results can be achieved by analysing the
strong motion recorded signals in terms of peak (PGA, PGV and PGD) and integral (Housner Intensity, I
H) seismic parameters. Additionally, an alternative time-domain representation of recorded signals has been used to furnish
a rapid comparison of traces recorded at different stations and along different directions. Some comparisons between the response
spectra derived from the recordings and the elastic demand spectra provided in the new seismic Italian code have also been
performed. PGA recorded values are very high and generally higher than code values for seismic actions with return period
T
R = 475 years. In some cases, this also happens for seismic actions with T
R up to 2,475 years. With regard to I
H, recorded values are generally higher for T
R = 475 years, whilst they are remarkably lower for T
R = 2,475 years. Accurate analyses have been carried out in the article to better understand the above differences and their
significance and implications. 相似文献
18.
M. Mucciarelli M. Bianca R. Ditommaso M. R. Gallipoli A. Masi C. Milkereit S. Parolai M. Picozzi M. Vona 《Bulletin of Earthquake Engineering》2011,9(1):263-283
After the recent Central Italy Earthquake of the 6th April 2009 (Mw = 6.3), the Italian and German engineer and geophysicist
Task Force carried out a wide characterization of sites, buildings and damages. In Navelli, a town about 35 km far from epicentre,
heavy damage occurred on a reinforced concrete (RC) building that represent an anomalous case of damage, when compared with
those occurred in the neighbouring area. In this paper, characterization of the site and damage of the Navelli RC Building
is reported and discussed. We performed ambient noise and strong motion measurements, installing one three-directional accelerometer
on each floor of the structure and two in free-field, and we have carried out repeated measurements using a couple of three-directional
tromometers. In the mean time, a geological survey was carried out and the site response was investigated, with the aid of
down-hole measurements. It was thus possible to investigate the structural response and damage taking into account site condition.
One of the main results of this work is that repeating analyses using ambient noise measurements show that the main structural
frequencies reached after the first damaging shock are constant over time, and then the structural behaviour appears stationary
at long term. On the other hand, the strong motion recordings show that the building exhibits a transient non-stationary behaviour
as the fundamental frequency changes during each aftershock, then returning to the starting value after each event. 相似文献
19.
Carbon and oxygen isotope analyses were made of representative samples of calcite and quartz from the carbonate deposits in the Tolfa Mountains mining district. Measurements were also made of hydrogen isotope compositions, filling temperatures and salinities of fluid inclusions in these minerals. There are three stages of mineralization at Tolfa. In stage I, characterized by calc-silicate hornfels, the carbonates have relatively high 18O values of 14.5 to 21.6 suggesting a rather low water/rock ratio. 13C values of –0.3 to 2.1 indicate that appreciable decarbonation or introduction of deep-seated carbon did not occur. Stage II is marked by phanerocrystalline carbonates; 18O values of 13.1 to 20.0 and 13C values of 0.7 to 5.0 identify them as hydrothermal veins rather than marbles. D values of –56 to –50 for inclusion fluids suggest a possible magmatic component to the hydrothermal fluid. Filling temperatures of coarse-grained samples of Calcite II are 309° to 362° C with a salinity range of 5.3 to 7.1 weight percent NaCl. Calculated 18O values of 11–12 for these fluids are again indicative of low water/rock ratios. The sparry calcites of stage III have 18O and 13C values of 8.1 to 12.9 and –1.7 to 3.2, respectively. D values of inclusion fluids are –40 to –33, clearly heavier than in earlier stages and similar to values of modern local ground waters. A salinity measurement of <0.1 weight percent NaCl in a sample of Calcite III is compatible with a relatively unaltered ground water origin for this fluid. Precipitation of the sparry calcite took place at much lower temperatures, around 160° C. For quartz, 18O values of 9.3 to 12.4 and D values for inclusions of –53 to –28 are consistent with its late occurrence and paragenetic link with associated carbonates. 相似文献
20.
Angelo Masi 《Bulletin of Earthquake Engineering》2003,1(3):371-395
The seismic vulnerability of some frame structures, typical of existing Reinforced Concrete buildings designed only to vertical
loads, has been evaluated. They are representative of building types widely present in the Italian building stock of the last
30 years. A simulated design of the structures has been made with reference to the codes in force, the available handbooks
and the current practice at the time of construction. The seismic response is calculated through non linear dynamic analyses
with artificial and natural accelerograms. Three main types have been examined: bare frames, regularly infilled frames and
pilotis frames. The results show a high vulnerability for the pilotis buildings: they can be assigned to the class B of the
European Macroseismic Scale of 1998 (EMS98). On the contrary, a low vulnerability (class D of EMS98) can be attributed to
the regularly infilled buildings: in this case collapse can be considered unlikely also with strong earthquakes. An intermediate
seismic behavior is shown by buildings without infills, whose vulnerability can be placed between the classes B and C of EMS98.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献