Aa. Vv., «Le Courrier balzacien»

Il fascicolo si apre con l’intervento di Anne-Marie Baron (Balzac, ou les hiéroglyphes de l’imaginaire, pp. 3-17), in cui l’A. traccia le linee fondamentali del rapporto tra Balzac e la scrittura, oggetto del suo recente studio pubblicato da Champion nel 2002. Secondo Baron, la scrittura rappresenta, per Balzac, la «face cachée de la comédie humaine», «elle est aussi et surtout cryptique» (p. 7) ed essa costituisce lo strumento privilegiato dallo scrittore per connotare, all’interno dell’univ..

PEelse: a 2D parallel spectral code for linear elastic analysis of seismic wave propagation. Implementation of seismic sources (plane wave and seismic moment tensor), absorbing boundaries and damping factor

PEelse2D is a spectral element, parallel, computer program for the analysis of complex 2D structure system, subject to transient dynamic loading conditions. PEelse2D is developed by the CRS4 team. The co-operation between the CRS4 and the Technical school of Milan (Department of Structural Engineering) is intended to equip the program of typical tools necessary for the simulation of seismic wave propagation into linear visco-elastic medium. The goal of the present report is to present the results obtained during the period 15 July – 14 September 2002, on three important topics: portability of PEelse2D; functionality of PEelse2D; implementation of the necessary tools for the analysis in the seismic wave field: most common sources in the seismic field (plane wave in the form of Ricker wavelet and seismic moment tensor (Madariaga, 1983)); internal soil dissipation as described by Kosloff and Kosloff (1986); Absorbing boundaries condition (Stacey, 1988)

The spectral element method as an effective tool for solving large scale dynamic soil-structure interaction problems

The spectral element method (SEM) is a powerful numerical technique naturally suited for wave propagation and dynamic soil-structure interaction (DSSI) analyses. A class of SEM has been widely used in the seismological field (local or global seismology) thanks to its capability of providing high accuracy and allowing the implementation of optimized parallel algorithms. We illustrate inthis contribution how the SEM can be effectively used also for the numerical analysis of DSSI problems, with reference to the 3D seismic response of a railway viaduct in Italy. This numerical analysis includes the combined effect of: a) strong lateral variations of soil properties; b) topographic amplification; c) DSSI; d) spatial variation of earthquake ground motion in the structural response. Some hints on the work in progress to effectively handle nonlinear problems with SEM are also given

Benchmark di una macchina bi-processore HP attraverso un codice di ricerca scientifico per lo studio di propagazione di onde sismiche (ELSE)

È stato realizzato un accurato "benchmark" di una macchina bi-processore Itanium2, fornita da HP, attraverso un codice di calcolo sviluppato per lo studio di fenomeni di propagazione sismica. Lo scopo è valutare le reali prestazioni di quella che si prevede essere la tecnologia più diffusa nei prossimi anni soprattutto nell'ambito della ricerca scientifica e nelle imprese caratterizzate da un'alta innovazione tecnologica, cioè le macchine a più processori con archittettura 64 bit, in ambiente UNIX (Linux ed HP-UX)

CUBIT and Seismic Wave Propagation Based Upon the Spectral-Element Method: An Advanced Unstructured Mesher for Complex 3D Geological Media

Unstructured hexahedral mesh generation is a critical part of the modeling process in the Spectral-Element Method (SEM). We present some examples of seismic wave propagation in complex geological models, automatically meshed on a parallel machine based upon CUBIT (Sandia Laboratory), an advanced 3D unstructured hexahedral mesh generator that offers new opportunities for seismologist to design, assess, and improve the quality of a mesh in terms of both geometrical and numerical accuracy. The main goal is to provide useful tools for understanding seismic phenomena due to surface topography and subsurface structures such as low wave-speed sedimentary basins. Our examples cover several typical geophysical problems: 1) “layer-cake” volumes with high-resolution topography and complex solid-solid interfaces (such as the Campi Flegrei Caldera Area in Italy), and 2) models with an embedded sedimentary basin (such as the Taipei basin in Taiwan or the Grenoble Valley in France)

Numerical prediction of low-frequency ground vibrations induced by high-speed trains at Ledsgaard, Sweden

none5R. Paolucci; A. Maffeis; L. Scandella; M. Stupazzini; M. VaniniPaolucci, Roberto; Maffeis, Andrea; L., Scandella; Stupazzini, Marco; Vanini, Manuel