Seismic response of masonry-infilled steel frames via multi-scale finite-element analyses     

Federico Margiacchi  Luca Salvatori  Maurizio Orlando  Mario De Stefano  Paolo Spinelli 《Bulletin of Earthquake Engineering》2016,14(12):3529-3546

Effects of masonry infills on the seismic vulnerability of steel frames is studied through multi-scale numerical modelling. First, a micro-modelling approach is utilized to define a homogenized masonry material, calibrated on experimental tests, which is used for modelling the nonlinear response of a one-story, single span, masonry-infilled portal under horizontal loads. Based on results of the micro-model, the constitutive behavior of a diagonal strut macro-element equivalent to the infill panel is calibrated. Then, the diagonal strut is used to model infill panels in the macro-scale analysis of a multi-span multi-story infilled moment-resisting (MR) steel frame. The seismic vulnerability of the MR frame is evaluated through a nonlinear static procedure. Numerical analyses highlight that infills may radically modify the seismic response and the failure mechanism of the frame, hence the importance of the infill correct modelling.  相似文献   

Fractal Dimension of Geologically Constrained Crater Populations of Mercury     

Paolo Mancinelli  Cristina Pauselli  Diego Perugini  Andrea Lupattelli  Costanzo Federico 《Pure and Applied Geophysics》2015,172(7):1999-2008

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High-Resolution Geophysical 3D Imaging for Archaeology by Magnetic and EM data: The Case of the Iron Age Settlement of Torre Galli,Southern Italy   总被引：1，自引：1，他引：0  

Federico Cella  Maurizio Fedi 《Surveys in Geophysics》2015,36(6):831-850

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Maximum likelihood algorithm for parametric component separation in cosmic microwave background experiments     

Radek Stompor  Samuel Leach  Federico Stivoli  Carlo Baccigalupi 《Monthly notices of the Royal Astronomical Society》2009,392(1):216-232

We discuss an approach to the component separation of microwave, multifrequency sky maps as those typically produced from cosmic microwave background (CMB) anisotropy data sets. The algorithm is based on the two-step, parametric, likelihood-based technique recently elaborated on by Eriksen et al., where the foreground spectral parameters are estimated prior to the actual separation of the components. In contrast with the previous approaches, we accomplish the former task with help of an analytically derived likelihood function for the spectral parameters, which, we show, yields estimates equal to the maximum likelihood values of the full multidimensional data problem. We then use these estimates to perform the second step via the standard, generalized-least-squares-like procedure. We demonstrate that the proposed approach is equivalent to a direct maximization of the full data likelihood, which is recast in a computationally tractable form. We use the corresponding curvature matrices to characterize statistical properties of the recovered parameters. We incorporate in the formalism some of the essential features of the CMB data sets, such as inhomogeneous pixel domain noise, unknown map offsets as well as calibration errors and study their consequences for the separation. We find that the calibration is likely to have a dominant effect on the precision of the spectral parameter determination for a realistic CMB experiment. We apply the algorithm to simulated data and discuss the results. Our focus is on partial sky, total intensity and polarization, CMB experiments such as planned balloon-borne and ground-based efforts, however, the techniques presented here should be also applicable to the full-sky data as for instance, those produced by the Wilkinson Microwave Anisotropy Probe ( WMAP ) satellite and anticipated from the Planck mission.  相似文献   

Modelling the cosmological co-evolution of supermassive black holes and galaxies – II. The clustering of quasars and their dark environment     

Silvia Bonoli  Federico Marulli  Volker Springel  Simon D. M. White  Enzo Branchini  Lauro Moscardini 《Monthly notices of the Royal Astronomical Society》2009,396(1):423-438

We use semi-analytic modelling on top of the Millennium simulation to study the joint formation of galaxies and their embedded supermassive black holes. Our goal is to test scenarios in which black hole accretion and quasar activity are triggered by galaxy mergers, and to constrain different models for the light curves associated with individual quasar events. In the present work, we focus on studying the spatial distribution of simulated quasars. At all luminosities, we find that the simulated quasar two-point correlation function is fit well by a single power law in the range  0.5 ≲ r ≲ 20  h ⁻¹ Mpc  , but its normalization is a strong function of redshift. When we select only quasars with luminosities within the range typically accessible by today's quasar surveys, their clustering strength depends only weakly on luminosity, in agreement with observations. This holds independently of the assumed light-curve model, since bright quasars are black holes accreting close to the Eddington limit, and are hosted by dark matter haloes with a narrow mass range of a few  10¹²  h ⁻¹ M_⊙  . Therefore, the clustering of bright quasars cannot be used to disentangle light-curve models, but such a discrimination would become possible if the observational samples can be pushed to significantly fainter limits. Overall, our clustering results for the simulated quasar population agree rather well with observations, lending support to the conjecture that galaxy mergers could be the main physical process responsible for triggering black hole accretion and quasar activity.  相似文献   

Value of perfect ENSO phase predictions for agriculture: evaluating the impact of land tenure and decision objectives     

David Letson  Carlos E. Laciana  Federico E. Bert  Elke U. Weber  Richard W. Katz  Xavier I. Gonzalez  Guillermo P. Podestá 《Climatic change》2009,97(1-2):145-170

In many places, predictions of regional climate variability associated with the El Niño–Southern Oscillation phenomenon offer the potential to improve farmers’ decision outcomes, by mitigating the negative impacts of adverse conditions or by taking advantage of favorable conditions. While the notion that climate forecasts are potentially valuable has been established, questions of when they may be more or less valuable have proven harder to resolve. Using simulations, we estimate the expected value of seasonal climate information under alternative assumptions about (a) land tenure (ownership vs. short-term leases) and (b) the decision maker’s objective function (expected utility vs. prospect theory value function maximization), employing a full range of plausible parameter values for each objective function. This allows us to show the extent to which the value of information depends on risk preferences, loss aversion, wealth levels and expectations, as well as situational constraints. Our results demonstrate in a non-laboratory decision context that, in some cases, psychologically plausible deviations from expected utility maximization can lead to substantial differences in estimates of the expected value of climate forecasts. Efforts to foster effective use of climate information and forecasts in agriculture must be grounded in a firm understanding of the goals, objectives and constraints of decision makers.  相似文献   

The contribution of satellite SAR-derived displacement measurements in landslide risk management practices     

Raspini  Federico  Bardi  Federica  Bianchini  Silvia  Ciampalini  Andrea  Del Ventisette  Chiara  Farina  Paolo  Ferrigno  Federica  Solari  Lorenzo  Casagli  Nicola 《Natural Hazards》2017,86(1):327-351

Natural Hazards - Landslides are common phenomena that occur worldwide and are a main cause of loss of life and damage to property. The hazards associated with landslides are a challenging concern...  相似文献   

Protecting innovative niches in the green economy: investigating the rise and fall of Solyndra, 2005–2011     

Federico Caprotti 《GeoJournal》2017,82(5):937-955

This article examines the establishment and development of a protected ‘green’ niche around the solar manufacturing industry in the United States in the 2000s. The paper uses the case of Solyndra, an innovative solar manufacturing corporation founded in 2005 and that went bankrupt in 2011, as a window into identifying the key factors that led to the failure of Solyndra. Solyndra was, at the time, the largest recipient of loan funding from the US Department of Energy, making it into the main representative of a key strategic industry identified as a target for federal support as part of US stimulus funding after the 2008 financial crisis. The analysis of the Solyndra failure case presented here highlights the need for strategic transitional niches to be shielded longitudinally by a strategic, entrepreneurial state, and considered in light of transnational exogenous factors. The article also argues for the importance of analysing discursive strategies that perform strategic niches as belonging to specific societal pathways.  相似文献   

Over 10 years of variation in Mediterranean reef benthic communities          下载免费PDF全文

Federico Betti  Giorgio Bavestrello  Marzia Bo  Valentina Asnaghi  Mariachiara Chiantore  Simone Bava  Riccardo Cattaneo‐Vietti 《Marine Ecology》2017,38(3)

During the last several decades, the Mediterranean littoral shallow water benthic communities have suffered significant changes in their structure and taxa composition. Despite numerous studies conducted to characterize these changes at various levels, it has always been very difficult to disentangle the effects of natural factors from anthropic ones. The main purpose of this work was to evaluate possible changes, over a 10‐year scale, in diversity and abundance of the most representative species of the benthic communities considered to be primarily and potentially affected by natural stressors in a highly protected area. Sets of macro‐photographs were taken in 2002–2003 of three sites inside a small bay called Ca’ dell'Oro, which is the “no entry—no take” zone of the Marine Protected Area of Portofino, in order to analyse the structure of the benthic communities at different depths over a short time scale. The same sampling was repeated 10 years later in 2013. In the 10‐year span, a significant change in the macroalgal coverage and composition was observed, while the overall richness and coverage of species remained almost unchanged. This process resulted in a significant reduction of the habitat complexity of the three‐dimensional algal components. Likewise, a remarkable change in terms of presence and abundance occurred among all zoobenthic components. The benthic communities seem to have suffered from detrimental effects probably caused by climatic events that have been occurring in recent years in the Ligurian Sea.  相似文献   

Tectonic vs. gravitational morphostructures in the central Eastern Alps (Italy): Constraints on the recent evolution of the mountain range   总被引：1，自引：0，他引：1  

Federico Agliardi  Andrea Zanchi  Giovanni B. Crosta   《Tectonophysics》2009,474(1-2):250

Deep-seated gravitational slope deformations (DSGSDs) influence landscape development in tectonically active mountain ranges. Nevertheless, the relationships among tectonics, DSGSDs, and topography are poorly known. In this paper, the distribution of DSGSDs and their relationships with tectonic structures and active processes, surface processes, and topography were investigated at different scales. Over 100 DSGSDs were mapped in a 5000 km² sector of the central Eastern Alps between the Valtellina, Engadine and Venosta valleys. Detailed lineament mapping was carried out by photo-interpretation in a smaller area (about 750 km²) including the upper Valtellina and Val Venosta. Fault populations were also analysed in the field and their mechanisms unravelled, allowing to identify different structural stages, the youngest being consistent with the regional pattern of the ongoing crustal deformation. Finally, four DSGSD examples have been investigated in detail by geological and 2D geomechanical modelling.DSGSDs affect more than 10% of the study area, and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur. Their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features, including regional nappe boundaries as well as NW–SE, N–S and NE–SW trending recent brittle structures. The kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force DSGSDs, although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism.  相似文献