1,721,001 research outputs found
3D Numerical Simulation of Soil-Structure Interaction Effect: The Acquasanta, Genoa, Railway Bridge
No full textIn this paper the soil-structure interaction problem is addressed by three-dimensional numerical simulation considering a challenging case study: a remarkable bridge, called “Acquasanta” bridge, located near Genoa and characterized by complex geological site conditions. The comparison between displacement time-histories of the structure considering or disregarding the soil-structure interaction effect is provided, pointing out that the three-dimensional site effects contribution to the increasing complexity of the dynamic response is very significant and cannot be neglected. The development of non-conforming meshing strategies allows us to tackle numerically and more efficiently the typically multi-scale wave propagation problem, from the far-field to the near-field, from the near-field to the soil-structure interaction effect
Numerical Study on the Role of Basin Geometry and Kinematic Seismic Source in 3D Ground Motion Simulation of the 22 February 2011 MW 6.2 Christchurch Earthquake
No full textThe main aim of this paper was to perform 3D numerical simulations
of the MW 6.2 Christchurch earthquake on 22 February 2011, the most devastating and deadliest event of the seismic sequence that struck the Canterbury Plains, and particularly the city of Christchurch, between September 2010 and June 2011, and to compare the numerical results with strong ground motion observations.
The numerical simulations of seismic wave propagation within the Canterbury Plains, where widespread damage was recognized during the post-earthquake reconnaissance surveys, were performed by means of the Spectral Element code GeoELSE (http://geoelse.stru.polimi.it), combining the following features: 1) two different kinematic finite fault models, provided by INGV and GNS seismic source inversion studies, and 2) two simplified models for the description of the interface between the stiff volcanic rock of the Banks Peninsula and the soft materials within the Canterbury Plains
Choice-predictive activity in parietal cortex during source memory decisions
No full textNeurobiological research has classically focused on perceptual decision-making, although many real-life decisions are based on information that is not currently available but stored in long-term memory. Previous studies have suggested that the lateral parietal cortex encodes decision-related signals during item recognition judgments. In the present fMRI study, we employed a parametric manipulation of evidence for source memory judgments and tested several hypotheses concerning memory decision signals in parietal cortex. As expected, the mean BOLD signal in several parietal regions was modulated by decision evidence. An analysis of the locally distributed pattern of activity, moreover, identified a parietal cluster showing significant choice-predictive activity even at the lowest level of decision evidence, with decoding accuracy that increased as a function of evidence. Decoding patterns were consistent across subjects as shown by a leave-one-subject-out classification analysis. Finally, we found that the pattern of choice-predictive activity in parietal lobe was temporally correlated with that observed in medial temporal regions traditionally associated with long-term memory functions. The present findings are consistent with a general role of lateral parietal regions located around the intraparietal sulcus in representing a decision variable for memory-based decisions
THE 22 FEBRUARY 2011 MW 6.3 CHRISTCHURCH EARTHQUAKE: 3D NUMERICAL SIMULATIONS OF STRONG GROUND MOTION
No full textPractice-induced and sequential modulations in the Simon task: evidence from pupil dilation
No full textRecent evidence showed that pupil dilation (PD) reflects modulations in the magnitude of the Simon interference effect due to correspondence sequence. In the present study we used this measure to assess whether these modulations, thought to result from cognitive control mechanisms, are influenced by prior practice with an incompatible stimulus-response (S-R) mapping. To this end, PD and reaction times (RTs) were recorded while participants performed a Simon task before and after executing a spatially incompatible practice. The sequential analysis revealed that PD mirrored the conflict-adaptation pattern observed in RTs. Crucially, sequential modulations were not affected by prior practice. These findings support the view that the modulations of the Simon effect due to prior practice and those due to correspondence sequence result from two different mechanisms, and suggest that PD can help to better understand the mechanisms underlying response selection and cognitive control in the Simon task
Free-field rotations during earthquakes: Relevance on buildings
No full textSoil rotations around horizontal axes, during an earthquake, are studied through records collected by closely spaced arrays of strong motion accelerometers. The cross power spectrum of accelerations at nearby stations has been generally utilized to describe the spatial distribution of the motion. A number of cross spectra have been obtained during the training of these arrays. To take profit of these elaborations, a mathematical relation is established between the cross power spectrum and the power spectrum of the rotation.
Rotation data presented by Liu et al, concerning 52 earthquake records collected at a single station in Taiwan, are compared with rotation data computed according to our procedure. The two series of data are suitably normalized to the peak horizontal acceleration. The data are shown in function of the distance from epicentre. The same ratio, computed according to our procedure, is in good agreement with the average value of these data.
Direct measurements and the present approach have lead to evaluations of rotation higher than those predicted by mathematical investigations on the basis of the wave propagation theory, for comparable circumstances.
The relevance of this input motion for relatively tall structures is examined, with reference to the structural effects that the horizontal motion concurrently provides. Meaningful will be ranked those effects of the order of magnitude of 20% or higher than those implied by the horizontal excitation.
For understanding the relevance on building structures, the procedure has two areas of concern: 1) the coherence implicit in the cross power spectra, which depends on the interpolation process of the original records, collected in the arrays of instruments, and 2) the relative importance of the vertical to the horizontal input motion.
As to the second item, the relevance of the rotation component on structures largely depends on the relative importance of the vertical to the horizontal input motion. When the records in an area a few km from the epicenter are considered, the response spectrum of vertical motion is comparable and in some records even higher, than that of horizontal motion, over the entire range of frequencies. This has been observed as well for the 2009 earthquake event of L’Aquila, Italy, and that at the Christchurch (New Zealand) 2011. When the response spectrum of vertical motion is comparable to that of horizontal motion, the effects of rotational motions on most engineering structures can be meaningful
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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