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51.
A total of 321 observations of the Delta Scuti star BD –6°4932, obtained in 1968 by Hall and Mallama (1970), are analyzed. We find four frequencies which represent the light curves satisfactorily.The three periods:P
1=0
.
d
240,P
3=0
.
d
182 andP
4=0
.
d
114 seem to correspond to the radial modes of pulsation withK=0, 1, and 3, respectively. The last periodP
2=0
.
d
220 can be related to a non-radial mode. 相似文献
52.
53.
54.
The Varnes classification of landslide types,an update 总被引:49,自引:31,他引:18
The goal of this article is to revise several aspects of the well-known classification of landslides, developed by Varnes (1978). The primary recommendation is to modify the definition of landslide-forming materials, to provide compatibility with accepted geotechnical and geological terminology of rocks and soils. Other, less important modifications of the classification system are suggested, resulting from recent developments of the landslide science. The modified Varnes classification of landslides has 32 landslide types, each of which is backed by a formal definition. The definitions should facilitate backward compatibility of the system as well as possible translation to other languages. Complex landslides are not included as a separate category type, but composite types can be constructed by the user of the classification by combining two or more type names, if advantageous. 相似文献
55.
56.
A simple numerical procedure for timely prediction of precipitation-induced landslides in unsaturated pyroclastic soils 总被引:4,自引:4,他引:0
In the last 20 years, several catastrophic precipitation-induced landslides have hit villages, towns and roads in Campania
(southern Italy), causing extensive damage and many fatalities. Although such phenomena have occurred since time immemorial,
recent urbanisation and infrastructural development have produced a major increase in landslide risk. Due to climatic changes
and further unavoidable increases in exposure, in the near future, the risk will become even greater. It is therefore high
time to develop reliable criteria for landslide prediction. The paper discusses the main factors which affect the triggering
of precipitation-induced landslides, highlighting the key role played by antecedent rainfalls which cannot be precisely accounted
for using empirical criteria. We propose a simple 1D numerical approach able to predict the evolution of the key factors governing
slope stability as a tool to predict the onset of slope failure, with potential benefits for early warning systems. The approach
is calibrated through a well-documented case history. 相似文献
57.
Olindo Zanotti José A. Font Luciano Rezzolla Pedro J. Montero 《Monthly notices of the Royal Astronomical Society》2005,356(4):1371-1382
We present a comprehensive numerical study of the dynamics of relativistic axisymmetric accretion tori with a power-law distribution of specific angular momentum orbiting in the background space–time of a Kerr black hole. By combining general relativistic hydrodynamics simulations with a linear perturbative approach we investigate the main dynamical properties of these objects over a large parameter space. The astrophysical implications of our results extend and improve two interesting results that have been recently reported in the literature. First, the induced quasi-periodic variation of the mass quadrupole moment makes relativistic tori of nuclear matter densities, as those formed during the last stages of binary neutron star mergers, promising sources of gravitational radiation, potentially detectable by interferometric instruments. Secondly, p-mode oscillations in relativistic tori of low rest-mass densities could be used to explain high-frequency quasi-periodic oscillations observed in X-ray binaries containing a black hole candidate under conditions more generic than those considered so far. 相似文献
58.
Andrews José de Lucena Otto Corrêa Rotunno Filho José Ricardo de Almeida França Leonardo de Faria Peres Luciano Nóbrega Rodrigues Xavier 《Theoretical and Applied Climatology》2013,111(3-4):497-511
This paper aims to map the thermal field in the metropolitan region of Rio de Janeiro (MARJ) considering the atmospheric characteristics and the land use that contribute to understanding the urban heat island. Three thermal maps are defined through the use of Landsat5-TM satellite images for three winter events chosen for the decades of 1980, 1990, and 2000, respectively. The results reveal a concentration of warmer cores in urban central areas as well as some local warmer areas in suburban region. Sites with lower temperatures correspond to vegetated areas which are away from the central part of the MARJ, including points of suburban areas. This work emphasizes the importance of the combined analysis of surface temperature with land use and atmospheric conditions, depicting a distinct pattern of heat islands for tropical climate. 相似文献
59.
60.
Cesare Barbieri Carlo Blanco Beatrice Bucciarelli Regina Coluzzi Andrea Di Paola Luciano Lanteri Gian Luca Li Causi Ettore Marilli Piero Massimino Vincenzo Mezzalira Stefano Mottola Roberto Nesci Alessandro Omizzolo Fernando Pedichini Francesca Rampazzi Corinne Rossi Ruggero Stagni Milcho Tsvetkov Roberto Viotti 《Experimental Astronomy》2003,15(1):29-43
There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for
the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better
scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates
of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated
scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating
Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce
the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the
overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes,
and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in
the course of this project have been already applied successfully to plates taken by other Observatories, for instance at
Byurakan and at Hamburg. 相似文献