104,882 research outputs found
A modal decomposition method for the analysis of long waves amplification at coastal areas
No full textThis paper presents a model for the evaluation of long waves amplification at coastal areas, based on a modal decomposition method. It is able of modelling the growth and the decay of the natural modes of the area under investigation, and their contribution to the total wave field. The model is an improvement of that developed by Bellotti et al. (2012b), that was able of calculating the frequencies and the shapes of the natural modes, but not their amplification under the action of forcing waves. Three test cases are used for the validation and to show the capabilities of the model. The first considers the long waves resonance into a long and narrow harbour/bay over a constant water depth. It is a case for which a high degree of wave trapping into the semi-enclosed coastal area is induced by the specific shape of the coastline. The second test deals with the propagation of a group of edge waves along a straight coast with a constant sloping bottom, generated in proximity of the shoreline by a special wave maker. The model in this case properly evaluates what are the edge waves modes that contribute to the total wave field. The third case involves the interaction of a solitary wave with a conical island, for which laboratory data are available. In this test a low degree of trapping exists, but it is interesting for the present aims as the propagation of the waves around the island is expected to occur under the form of wave modes partially trapped by the bathymetry i.e. edge waves, excited by the transient wave arriving from offshore. On the basis of the tests results it is shown what is the role of the more relevant natural modes in the formation of the total surface elevation
Le carte di Felice Bellotti
No full textLa figura di Felice Bellotti, traduttore di tragediografi greci, attraverso le sue cart
Forecasting and Stress Testing Credit Card Default with Dynamic Models
No full textTypically models of credit card default are built on static data, often collected at timeof application. We consider alternative models that also include behavioural dataabout credit card holders and macroeconomic conditions across the credit cardlifetime, using a discrete survival analysis framework. We find that dynamic modelsthat include these behavioural and macroeconomic variables give statisticallysignificant improvements in model fit which translates into better forecasts of defaultat both account and portfolio level when applied to an out-of-sample dataset. Additionally, by simulating extreme economic conditions, we show how thesemodels can be used to stress test credit card portfolios
High performance scientific computing using distributed infrastructures. Results and scientific applications derived from the italian PON ReCaS project
No full textThe book aims to provide a deep look into ialian actions taken in some fields of science and high performance computing (HPC), and the italian effort to bridge the gap with respect to Europe. The italian PON ReCaS Project is written for graduate readers and professionals in the field of high performance computing. It presents and discusses innovative and important technological solutions, and describes interesting resuklts in variou fields of application.ReCaS stands for "Rete di Calcolo ad Alte Prestazioni per SuperB e altre applicazioni" and is a computing network infrastructure in Southern Italy devoted to scientific and non-scientific applications within the vision of a common europeamn infrastructure for computing, stiorage and network
Closure to "Treatment of wave breaking and total absorption in a mild-slope equation FEM model" by Gian Mario Beltrami, Giorgio Bellotti, Paolo De Girolamo, and Paolo Sammarco
No full textA preliminary study on wave shoaling and evolution up to the shoreline by means of a Boussinesq-type model.
No full textWave forces on vertical caissons with retreated wall: A first experimental insight
No full textThis paper presents a physical model study of wave induced forces on a composite vertical breakwater, where the crown wave wall is retreated with respect to the front face of the caisson. Four different configurations (one flushed wall and three retreated wall configurations) have been tested under regular wave conditions, aiming at providing a first experimental insight on the increase/reduction of the wave loads acting on the structure. The analysis of the experimental results allows to describe the basic phenomena involved and to identify the physical/geometrical drivers, which are expected to play a role on the force increase/reduction factor. Thus, detailed processing of both forces/moments (synchronous analysis) and pressures (asynchronous analysis) on the whole structure, the wall and the caisson trunk, together with the analysis of reflection coefficients as a function of the wall position, are presented and discussed in the paper. The experimental evidences suggest that, at least for the four configurations tested, the global forces acting on the caisson vary significantly depending on the wall position, resulting in a reduction between 5% and 31% for high energy sea states. A similar behavior is found considering the global moments. Furthermore, the synchronous analysis of the forces highlighted that the physical/geometrical drivers, identified in the present study, can have both a concordant and antithetical action among them, then resulting in increasing or decreasing, respectively, forces acting on the structure, if compared with the flushed wall configuration
Integral flow properties of the swash zone and averaging. Part 2. Shoreline boundary conditions for wave-averaged models
No full textShoreline boundary conditions for nearshore hydrodynamic models are discussed on the basis of the swash zone equations of Brocchini & Peregrine (1996). Swash zone flows are investigated further using the shallow water equations. Results from numerical computations are used to guide approximation to provide more practical boundary conditions for wave-averaged flows. Approximate boundary conditions, valid for small values of the rate of change of the mean water volume in the swash zone, are found which allow explicit computation of a non-zero mean water depth at the mean shoreline. This is computed in terms of the local height of the short waves. Implementation issues are also discussed
Sintesi e numero nell'ultimo Cassirer
No full textIn questa breve nota discutiamo alcuni aspetti di una nozione in senso lato kantiana di sintesi, evidenziati da Ernst Cassirer nella fase finale del suo pensiero specificamente in rapporto alla questione della definizione del concetto di numero, mostrando quali conseguenze ne tragga l’autore, ad esempio limitando decisamente il ruolo logico della sussunzione nelle proposizioni matematiche
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