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The application of neural networks as classifiers of seismic events is described with the aim of developing an automatic system for the classification of explosion quakes at the Stromboli volcano. The architecture of the network that we trained to identify four different classes of shocks was a Multi-Layer Perceptron, using the Back Error Propagation algorithm. Five different approaches for representing the information embedded in the seismograms, both in the time and in the frequency domain, were considered, and the results compared. The direct use of the time series of the shocks was not satisfactory. The auto-correlation function worked well, but in some cases it was misleading. A better performance was obtained with a frequency domain representation. Finally, the use of the envelope function did not work well. Combining parameters such as the auto-correlation and envelope functions can improve one source of error, but it may introduce new ones. The performance obtained highlights the importance of the data attributes used for the training of the network. Topologies with eight neurons in a single hidden layer gave, on average, the best results among the considered neural network structures. The overall results provide a large number of events (89% with the best performance) correctly classified, indicating that this automatic technique is reliable, and encouraging further applications in the field of volcanic seismology. 相似文献
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Laura Graziani Andrea Tertulliani Alessandra Maramai Antonio Rossi Luca Arcoraci 《Journal of Seismology》2017,21(5):1219-1227
The aim of this paper is to provide a complete and reliable macroseismic knowledge of the events that stroke a large area in Central Italy on 7 and 11 May 1984. Previous studies, together with original accounts integrated with new and unpublished information, have been gathered and examined in order to re-evaluate macroseismic intensities in terms of the European Macroseismic Scale (EMS98). New intensity maps have been compiled; the total number of localities with available information for both the shocks increases from 1254 of the previous study to 1576. On the basis of the new dataset, the macroseismic magnitude of the first shock is MW 5.6 which is lower than the previous macroseismic computation (MW 5.7). Moreover, the topic of assessing macroseismic intensity in the presence of multiple shocks has been also investigated, proposing an unconventional approach to presenting the macroseismic data: an overall picture of the cumulative effects produced by all the seismic sequence is given to support a partial but faithful reconstruction of the second shock. This approach is inspired by the common experience in interpreting historical seismic sequences and gives a picture of the impact of the 1984 events on the territory. 相似文献
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Observations of physical effects from tsunamis of December 30, 2002 at Stromboli volcano, southern Italy 总被引：1，自引：0，他引：1
Stefano Tinti Alessandra Maramai Alberto Armigliato Laura Graziani Anna Manucci Gianluca Pagnoni Filippo Zaniboni 《Bulletin of Volcanology》2006,68(5):450-461
On December 30, 2002, following an intense period of activity of Stromboli volcano (south Tyrrhenian Sea, Italy), complex mass failures occurred on the northwest slope of the mountain which also involved the underwater portion of the volcanic edifice for a total volume of about 2–3×107 m3. Two main landslides occurred within a time separation of 7 min, and both set tsunami waves in motion that hit the coasts of Stromboli causing injuries to three people and severe damage to buildings and structures. The tsunamis also caused damage on the island of Panarea, some 20 km to the SSE from the source. They were observed all over the Aeolian archipelago, at the island of Ustica to the west, along the northern Sicily coasts to the south as well as along the Tyrrhenian coasts of Calabria to the east and in Campania to the north. This paper presents field observations that were made in the days and weeks immediately following the events. The results of the quantitative investigations undertaken in the most affected places, namely along the coasts of Stromboli and on the island of Panarea, are reported in order to highlight the dynamics of the attacking waves and their impact on the physical environment, on the coastal structures and on the coastal residential zone. In Stromboli, the tsunami waves were most violent along the northern and northeastern coastal belt between Punta Frontone and the village of Scari, with maximum runup heights of about 11 m measured on the beach of Spiaggia Longa. Measured runups were observed to decay rapidly with distance from the source, typical of tsunami waves generated by limited-area sources such as landslides. 相似文献
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Tanvir N. R. Le Floc’h E. Christensen L. Caruana J. Salvaterra R. Ghirlanda G. Ciardi B. Maio U. D’Odorico V. Piedipalumbo E. Campana S. Noterdaeme P. Graziani L. Amati L. Bagoly Z. Balázs L. G. Basa S. Behar E. De Cia A. Valle M. Della De Pasquale M. Frontera F. Gomboc A. Götz D. Horvath I. Hudec R. Mereghetti S. O’Brien P. T. Osborne J. P. Paltani S. Rosati P. Sergijenko O. Stanway E. R. Szécsi D. Tot́h L. V. Urata Y. Vergani S. Zane S. 《Experimental Astronomy》2021,52(3):219-244
Experimental Astronomy - At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer... 相似文献
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Practical Estimate of Deformations and Stress Relief Factors for Deep Tunnels Supported by Shotcrete 总被引：1，自引：1，他引：1
Summary. Even though ground-support interaction in the vicinity of the tunnel face is a typical 3D problem, tunnel support design is
usually based on simplified plane strain models, which are strongly dependent on the assumed degree of ground stress relief
at the time of lining installation. The paper focuses on tunnels supported by shotcrete close to the face, where the interaction
between the loading process and progressive hardening of the green shotcrete makes the problem time-dependent. A constitutive
law characterized by the time-dependent stiffness and strength of the shotcrete is employed herein. The results of an extensive
parametric study based on 3D axisymmetric models are presented in the form of non-dimensional design charts, which can provide
guidance to a preliminary evaluation of convergences and support loadings.
Moreover a strategy is proposed to enhance the capability of simplified design methods (2D models, Convergence-Confinement
Method). This consists in a “guided estimate” of stress relief factors, which again is based on the results of 3D time-dependent
analyses. Finally, by way of example, the proposed method is applied to two well-documented case-histories. 相似文献
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Giorgio Graziani Sergio Lucchesi Eugenio Scandale 《Physics and Chemistry of Minerals》1990,17(5):379-384
Growth marks of pegmatite beryls can be divided into general and specific in relation to their types and distributions. Dislocation absence and growth bands have been recognized as general growth marks of the environment while minor element concentrations and optical anomalies as specific to the local growth medium. 相似文献
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The New Catalogue of Italian Tsunamis 总被引：6，自引：0，他引：6
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Carlo Graziani 《New Astronomy》2011,16(2):57-64
Beginning with the 2002 discovery of the “Amati Relation” of GRB spectra, there has been much interest in the possibility that this and other correlations of GRB phenomenology might be used to make GRBs into standard candles. One recurring apparent difficulty with this program has been that some of the primary observational quantities to be fit as “data” – to wit, the isotropic-equivalent prompt energy Eiso and the collimation-corrected “total” prompt energy Eγ – depend for their construction on the very cosmological models that they are supposed to help constrain. This is the so-called “circularity problem” of standard candle GRBs. This paper is intended to point out that the circularity problem is not in fact a problem at all, except to the extent that it amounts to a self-inflicted wound. It arises essentially because of an unfortunate choice of data variables – “source-frame” variables such as Eiso, which are unnecessarily encumbered by cosmological considerations. If, instead, the empirical correlations of GRB phenomenology which are formulated in source-variables are mapped to the primitive observational variables (such as fluence) and compared to the observations in that space, then all taint of circularity disappears. I also indicate here a set of procedures for encoding high-dimensional empirical correlations (such as between Eiso, , and ) in a “Gaussian Tube” smeared model that includes both the correlation and its intrinsic scatter, and how that source-variable model may easily be mapped to the space of primitive observables, to be convolved with the measurement errors and fashioned into a likelihood. I discuss the projections of such Gaussian tubes into sub-spaces, which may be used to incorporate data from GRB events that may lack some element of the data (for example, GRBs without ascertained jet-break times). In this way, a large set of inhomogeneously observed GRBs may be assimilated into a single analysis, so long as each possesses at least two correlated data attributes. 相似文献
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D. Lee G. Xia C. Daley A. Dubey S. Gopal C. Graziani D. Lamb K. Weide 《Astrophysics and Space Science》2011,336(1):157-162
FLASH is a publicly available astrophysical community code designed to solve highly compressible multi-physics reactive flows.
We are adding capabilities to FLASH that will make it an open science code for the academic HEDP community. Among many important
numerical requirements, we consider the following features to be important components necessary to meet our goals for FLASH
as an HEDP open toolset. First, we are developing computationally efficient time-stepping integration methods that overcome
the stiffness that arises in the equations describing a physical problem when there are disparate time scales. To this end,
we are adding two different time-stepping schemes to FLASH that relax the time step limit when diffusive effects are present:
an explicit super-time-stepping algorithm (Alexiades et al. in Com. Num. Mech. Eng. 12:31–42, 1996) and a Jacobian-Free Newton-Krylov implicit formulation. These two methods will be integrated into a robust, efficient, and
high-order accurate Unsplit Staggered Mesh MHD (USM) solver (Lee and Deane in J. Comput. Phys. 227, 2009). Second, we have implemented an anisotropic Spitzer-Braginskii conductivity model to treat thermal heat conduction along
magnetic field lines. Finally, we are implementing the Biermann Battery term to account for spontaneous generation of magnetic
fields in the presence of non-parallel temperature and density gradients. 相似文献