Database and Geographic Information System (GIS) for the Via Francigena: a New Way to Read Sigeric’s itinerary

In order to define the path of a medieval road, it is essential to use different kind of sources, like the written texts, the archaeological and material remains referred to the road, the study of the geomorphological context, the toponymy. Modern technologies can help us to examine and use all these sources: first of all, the creation of a database could permit to manage all the data we have about a road; secondly, the database could be loaded in a GIS software, in order to answer to some historical, archaeological and topographical questions. This methodology can be applied to the “Via Francigena” case: starting from Sigeric’s itinerary, which is the main source about the road, it is possible to create a database containing all the data about the submansiones mentioned by the text. Furthermore, loading the database in a GIS software gives the possibility to study the road in its entire length, helping us to understand the relationships between the Via Francigena, the other itineraries and the ancient roads. But at the same time, this enables us to study the route in a specific region, and it could also be the opportunity to comprehend the evolution of the historical landscapes, focusing both on the track of the road and on the territory that the road has conditioned, according to the concept of “street areas”

Implementation and appraisal of a stochastic model for particle tracking in turbulent flow

The purpose of this thesis is to analyse the results of numerical computations of polydispersed turbulent two-phase flows using a LES/VFDF approach. In this approach, the numerical solution is obtained by resorting to a hybrid method, where the fluid properties are computed by solving filtered-field (LES) equations whereas the local instantaneous properties of the particles are determined by solving stochastic differential equations (SDEs). The fundamentals of the general formalism are recalled in the first part, while the second part is focused on the work of implementation of the stochastic module and on the tests of consistency carried out to validate the code. Finally some results are shown for particle preferential concentration in a turbulent channel

Analysis of Dangerous Sea States in the Northwestern Mediterranean Area

Extreme sea waves, although rare, can be notably dangerous when associated with energetic sea states and can generate risks for the navigation. In the last few years, they have been the object of extensive research from the scientific community that helped with understanding the main physical aspects; however, the estimate of extreme waves probability in operational forecasts is still debated. In this study, we analyzed a number of sea-states that occurred in a precise area of the Mediterranean sea, near the location of a reported accident, with the objective of relating the probability of extreme events with different sea state conditions. For this purpose, we performed phase-resolving simulations of wave spectra obtained from a WaveWatch III hindcast, using a Higher Order Spectral Method. We produced statistics of the sea-surface elevation field, calculating crest distributions and the probability of extreme events from the analysis of a long time-series of the surface elevation. We found a good matching between the distributions of the numerically simulated field and theory, namely Tayfun second- and third- order ones, in contrast with a significant underestimate given by the Rayleigh distribution. We then related spectral quantities like angular spreading and wave steepness to the probability of occurrence of extreme events finding an enhanced probability for high mean steepness seas and narrow spectra, in accordance with literature results, finding also that the case study of the reported accident was not amongst the most dangerous. Finally, we related the skewness and kurtosis of the surface elevation to the wave steepness to explain the discrepancy between theoretical and numerical distributions

Direct numerical simulation of bubble-induced turbulence

We report on an investigation of bubble-induced turbulence. Bubbles of a size larger than the dissipative scale cannot be treated as pointwise inclusions, and generate important hydrodynamic fields in the carrier fluid when in motion. Furthermore, bubble motions may induce a collective agitation due to hydrodynamic interactions which display some turbulent-like features. We tackle this complex phenomenon numerically, performing direct numerical simulations with a volume-of-fluid method. In the first part of the work, we perform both two-dimensional and three-dimensional tests in order to determine appropriate numerical and physical parameters. We then carry out a highly resolved simulation of a three-dimensional bubble column, with a set-up and physical parameters similar to those used in laboratory experiments. This is the largest simulation attempted for such a configuration and is only possible thanks to adaptive grid refinement. Results are compared both with experiments and previous coarse-mesh numerical simulations. In particular, the one-point probability density function of the velocity fluctuations is in good agreement with experiments. The spectra of the kinetic energy show a clear k(-3) scaling. The mechanisms underlying the energy transfer and notably the possible presence of a cascade are unveiled by a local scale-by-scale analysis in physical space. The comparison with previous simulations indicates to what extent simulations not fully resolved may yet give correct results, from a statistical point of view

Phenylethynylbenzenesulfonamide regioisomers strongly and selectively inhibit the transmembrane tumor-associated carbonic anhydrase isoforms IX and XII over the cytosolic isoforms I and II

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