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排序方式: 共有120条查询结果,搜索用时 31 毫秒
31.
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
32.
Overview of the Italian strong motion database ITACA 1.0 总被引:3,自引:2,他引:1
Francesca Pacor Roberto Paolucci Lucia Luzi Fabio Sabetta Andrea Spinelli Antonella Gorini Mario Nicoletti Sandro Marcucci Luisa Filippi Mauro Dolce 《Bulletin of Earthquake Engineering》2011,9(6):1723-1739
The Italian Strong Motion Database, ITACA, was developed within projects S6 and S4, funded in the framework of the agreements
between the Italian Department of Civil Protection (Dipartimento della Protezione Civile, DPC) and the Istituto Nazionale
di Geofisica e Vulcanologia (INGV), starting from 2005. The alpha version of the database was released in 2007 and subsequently
upgraded to version 1.0 after: (i) including the most recent strong motion data (from 2005 to 2007) recorded in Italy, in
addition to the 2008 Parma earthquake, M 5.4, and the M ≥ 4.0, 2009 Abruzzo seismic events; (ii) processing the raw strong
motion data using an updated procedure; (iii) increasing the number of stations with a measured shear wave velocity profile;
(iv) improving the utilities to retrieve time series and ground motion parameters; (v) implementing a tool for selecting time
series in agreement with design-response spectra; (vi) compiling detailed station reports containing miscellaneous information
such as photo, maps and site parameters; (vii) developing procedures for the automatic generation of station reports and for
the updating of the header files. After such improvements, ITACA 1.0 was published at the web site , in 2010. It presently contains 3,955 three-component waveforms, comprising the most complete catalogue of the Italian accelerometric
records in the period 1972–2007 (3,562 records) and the strongest events in the period 2008–2009. Records were mainly acquired
by DPC through its Accelerometric National Network (RAN) and, in few cases, by local networks and temporary stations or networks.
This paper introduces the published version of the Italian Strong Motion database (ITACA version 1.0) together with main improvements
and new functionalities. 相似文献
33.
S. Lovati M. K. H. Bakavoli M. Massa G. Ferretti F. Pacor R. Paolucci E. Haghshenas M. Kamalian 《Bulletin of Earthquake Engineering》2011,9(6):1987-2005
In the present work the seismic site response of Narni ridge (Central Italy) is evaluated by comparing experimental results
and numerical simulations. The inhabited village of Narni is located in central Apennines at the top of a steep massive limestone
ridge. From March to September 2009 the site was instrumented with 10 weak-motion stations, 3 of which located at the base
of the ridge and 7 at the top. The velocimetric network recorded 642 events of ML up to 5.3 and hypocentral distance up to about 100 km. The great amount of data are related to the April 2009 L’Aquila sequence.
The site response was analyzed using both reference (standard spectral ratio, SSR) and non reference spectral techniques (horizontal
to vertical spectral ratio, HVSR). Moreover directional analyses were performed in order to evaluate the influence of the
ridge orientation with respect to the selected source-site paths. In general the experimental results show amplification factors
for frequencies between 4 and 5 Hz for almost all stations installed along the crest. The SSR technique provides amplification
factors up to 4.5 in a direction perpendicular to the main elongation of the ridge. The results obtained from the data analyses
were used as a target for bidimensional and tridimensional numerical simulations, performed using a hybrid finite-boundary
element method and a boundary element method for 2D and 3D modelling, respectively. In general, the results obtained through
numerical simulation fit well the experimental data in terms of range of amplified frequencies, but they underestimate by
a factor of about 2 the observed amplifications. 相似文献
34.
Francesca Pacor Roberto Paolucci Gabriele Ameri Marco Massa Rodolfo Puglia 《Bulletin of Earthquake Engineering》2011,9(6):1741-1759
The published version 1.0 of the new Italian strong-motion database ITACA (Italian ACcelerometric Archive, ) includes to date (December 2010) about 4,000 three-component waveforms up to M 6.9, from more than 1,800 earthquakes up
to 6.9, recorded by about 400 stations in the period 1972–2009. The uncorrected and corrected strong motion data are archived
and can be retrieved with their metadata, concerning events, stations and waveforms. The aim of this paper is to present the
procedures for processing the records included in ITACA, accounting for the heterogeneity of this data set, both in terms
of quality and amplitude of records as well as illustrating the main features of the ITACA strong-motion dataset. Later, we
focus on the “exceptional” ground-motion records, that we, conventionally, denote as those having peak acceleration and peak
velocity larger than 300 cm/s2 and 15 cm/s, respectively. These records are less than 2% of the whole ITACA dataset but they are the most relevant for the
seismic hazard and engineering implications. Such large peak values, recorded at distances up to 30 km, are related not only
to the strongest Italian earthquakes, but also to events with magnitude down to 4. Furthermore, we investigate the dependence
of the largest peak values on horizontal and vertical directions and on source-to-site distance. 相似文献
35.
Information about space distribution is collected for selected classes of evolving stars in the globular cluster M13. After a rigorous elimination of field stars, three samples are examined, corresponding to the red giant stage (G), the blue (B) and the yellow (YG) parts of the horizontal branch. It is shown that results are easy to understand in terms of:
- A substantial mass loss in the H-shell burning stage;
- Evolution along the horizontal branch from the blue side to the red one;
- A mixing in the observed giant branch of two populations with sensible differences in masses.
36.
Stefano Lo Russo Glenda Taddia Loretta Gnavi Vittorio Verda 《Hydrogeology Journal》2014,22(1):205-216
A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. This is particularly important to avoid interference with previously existing groundwater uses (wells) and underground structures. Temperature anomalies are detected through numerical methods. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple installations. The neural network is trained using the results from a CFD model (FEFLOW) applied to the installation at Politecnico di Torino (Italy) under several operating conditions. The final results appeared to be reliable and the temperature anomalies around the injection well appeared to be well predicted. 相似文献
37.
Luca Salvati Vittorio Gargiulo Morelli Kostas Rontos Alberto Sabbi 《Urban geography》2013,34(3):376-394
This paper quantifies the extent of exurban development in Mediterranean Europe. The assessment was carried out by studying changes in the urban-to-rural population density gradient between the years 1950 and 2010. Three of the six urban regions in this study have experienced population growth and moderate urban concentration, while two regions appear to be shifting toward population decline and urban de-concentration after having experienced compact expansion. A phase of recent re-urbanization has been observed in one region. Altogether, these findings indicate a common path of urban expansion among representative Mediterranean regions between 1950 and 1980 while, in the following period, the cities experienced distinct development phases. From this study, we conclude that exurban development is mainly the product of a shift from compact and dense to semi-compact and intermediate-density settlements. [Key words: semi-dense urban growth, density-distance curve, Mediterranean Europe]. 相似文献
38.
Schroeder T Devlin MJ Brando VE Dekker AG Brodie JE Clementson LA McKinna L 《Marine pollution bulletin》2012,65(4-9):210-223
Riverine freshwater plumes are the major transport mechanism for nutrients, sediments and pollutants into the Great Barrier Reef (GBR) lagoon and connect the land with the receiving coastal and marine waters. Knowledge of the variability of the freshwater extent into the GBR lagoon is relevant for marine park management to develop strategies for improving ecosystem health and risk assessments. In this study, freshwater extent has been estimated for the entire GBR lagoon area from daily satellite observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) between 2002 and 2010. To enable a reliable mapping of freshwater plumes we applied a physics-based coastal ocean colour algorithm, that simultaneously retrieves chlorophyll-a, non-algal particulate matter and coloured dissolved organic matter (CDOM), from which we used CDOM as a surrogate for salinity (S) for mapping the freshwater extent. 相似文献
39.
In this paper, different formulations of a macro‐element model for non‐linear dynamic soil‐structure interaction analyses of structures lying on shallow foundations are first reviewed, and secondly, a novel formulation is introduced, which combines some of the characteristics of previous approaches with several additional features. This macro‐element allows one to model soil‐footing geometric (uplift) and material (soil plasticity) non‐linearities that are coupled through a stiffness degradation model. Footing uplift is introduced by a simple non‐linear elastic model based on the concept of effective foundation width, whereas soil plasticity is treated by means of a bounding surface approach in which a vertical load mapping rule is implemented. This mapping is particularly suited for the seismic loading case for which the proposed model has been conceived. The new macro‐element is subsequently validated using cyclic and dynamic large‐scale laboratory tests of shallow foundations on dense sand, namely: the TRISEE cyclic tests, the Public Works Research Institute and CAMUS IV shaking table tests. Based on this comprehensive validation process against a set of independent experimental results, a unique set of macro‐element parameters for shallow foundations on dense sand is proposed, which can be used to perform predictive analyses by means of the present model. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
40.
Effect of underground cavities on surface earthquake ground motion under SH wave propagation 总被引:2,自引:0,他引:2
A theoretical approach is presented to study the antiplane seismic response of underground structures, subjected to the incidence of both plane and cylindrical waves. The structure is assumed to be a circular inclusion embedded in a homogenous, isotropic and linear visco‐elastic halfspace. The inclusion may consist either of a cavity, with or without a ring‐shaped boundary, or it may be filled in with a linear‐elastic material, without loss of generality. The analytical solution is obtained using expansions of wave functions in terms of Bessel and Hankel functions, relying on the technique of images and the use of Graf's addition theorem to enforce the boundary conditions. The effects of underground cavities on surface earthquake ground motion are studied as a function of the size of the cavity, its embedment depth, the frequency content of the excitation, the incidence angle and the distance from the axis of symmetry of the cavity itself. A simple application of Rayleigh's method allows us to verify that the ground surface response is dominated by the fundamental vibration mode of the portion of soil between the cavity and ground surface itself, in the frequency range of interest for engineering purposes. A simple relationship to estimate the fundamental natural frequency as a function of the embedment depth of the cavity is given. Finally, amplification factors on response spectra are obtained, to provide a practical insight into the effect of an underground cavity on surface ground motion during real earthquakes. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献