2,116 research outputs found

    L'albo illustrato un crocevia di linguaggi

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    L’albo illustrato è, per sua natura, caratterizzato dalla contaminazione di linguaggi diversi e dalla polisemia che nasce dal fruttuoso incontro tra testo e immagine, produttore di sempre nuovi testi. Esso si pone al servizio di un processo in cui la costruzione di una competenza testuale, fondata principalmente sul pensiero logico, deve procedere insieme alla stimolazione e all’utilizzo del pensiero analogico metaforico e combinatorio. I silent books dell’illustratrice sudcoreana Suzy Lee, che costituiscono quella che in un secondo momento l’autrice stessa definirà come la “trilogia del limite” (“L’onda”, “Ombra” e “Mirror”), si propongono quale terreno di interessante e prolifica analisi del meccanismo polialfabetico dell’albo illustrato con quel loro valicare i limiti anche fisici posti dal libro volgendo lo sguardo del lettore verso una nuova prospettiva

    The VOL-CALPUFF model for atmospheric ash dispersal: 2. Application to the weak Mount Etna plume of July 2001

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    Here the application of the VOL-CALPUFF model by Barsotti et al. to a weak plume erupted from Mount Etna in July 2001 is presented and discussed. The reconstruction of the explosive event was obtained by using high-resolution weather forecasts, produced by a mesoscale nonhydrostatic model, and volcanic source data coming from observations and analytical studies. The plume rise and atmospheric dispersal models were investigated over 5 d of eruption mostly in terms of column height, aerial ash concentration, and ground deposition. Modeling results are shown as a function of various source conditions and compared to independent observations derived from satellite images and deposit mapping. The application of VOL-CALPUFF clearly highlights the crucial role played by meteorological conditions in determining dispersal dynamics. Some of the most important effects described by the model are (1) the large wind field influence on the plume height determination and tilting, (2) the contrasting dispersal patterns of ash particles of different sizes, (3) the complex and somehow nonintuitive distribution of ash on the ground resulting in preferential directions of dispersal and quite irregular deposit patterns, and (4) the impossibility to reproduce both the column height and the deposit accumulation pattern by adopting a steady state vent mass flow rate over the investigated 4-d period due to observed temporal changes in eruption dynamics. Modeling results also suggest the need for further integration of simulation outcomes with remote sensing and field reconstructions on ash dispersal processes in future

    The VOL-CALPUFF model for atmospheric ash dispersal. II. Application to the weak Etna plume of July 2001

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    The application of the VOL-CALPUFF model (\cite{barsotti}, this issue) to a weak plume erupted from Mt. Etna in July 2001 is here presented and discussed. The reconstruction of the explosive event was obtained by using high-resolution weather forecasts, produced by a mesoscale non-hydrostatic model, and volcanic source data coming from observations and analytical studies. The plume rise and atmospheric dispersal models were investigated over five days of eruption mostly in terms of column height, aerial ash concentration and ground deposition. Modeling results are shown as a function of various source conditions and compared to independent observations derived from satellite images and deposit mapping. The application of VOL-CALPUFF clearly highlights the crucial role played by meteorological conditions in determining dispersal dynamics. Some of the most important effects described by the model are: a) the large wind field influence on the plume height determination and tilting, b) the contrasting dispersal patterns of ash particles of different sizes, c) the complex and somehow non-intuitive distribution of ash on the ground resulting in preferential directions of dispersal and quite irregular deposit patterns, d) the impossibility to reproduce both the column height and the deposit accumulation pattern by adopting a steady-state vent mass flow rate over the investigated four-day period due to observed temporal changes in eruption dynamics. Modeling results also suggest the need for further integration of simulation outcomes with remote sensing and field reconstructions on ash dispersal processes in future

    The VOL-CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation

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    We present a new modeling tool, named VOL-CALPUFF, that is able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely used in environmental applications of pollutant dispersion, that describes the dispersal process in both the proximal and distal regions and also in the presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 h. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, this paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper, Barsotti and Neri present a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) with the specific aim of comparing model predictions with independent observations

    Single-layer spherical geodesic domes interacting with a network of inflatable beams

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    In this paper we propose an example of a thin geodesic spherical dome composed by a lattice of inflatable interacting beams. The geometry of the lattice is determined by searching for the minimum variation of the characteristic dimensions of the elements that make up the dome (length of the bars and area of the panels). A first illustration of the mechanical response of the structure is given, with reference to the loads that usually are assumed to act on this type of shell

    The eruption in Fagradalsfjall (2021, Iceland): how the operational monitoring and the volcanic hazard assessment contributed to its safe access

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    After more than a year of unrest, a small effusive eruption commenced in Fagradalsfjall, Iceland, on 19 March 2021. The eruption lasted six months. The first six weeks were characterized by multiple fissure openings, and the remainder was dominated by effusive activity from a single crater. During the eruption, lava and low-level gases propagated over the complex terrain: a hyaloclastite massif with mountain peaks up to about 350 m asl with valleys in between. The area is uninhabited, but easily accessible at about 30 km distance from ReykjavĂ­k. While the eruption was ongoing, more than 356,000 tourists visited the eruptive site. To maintain low risk access to the area, it was critical to monitor the eruption (including opening of new fissures) in real-time, forecast the transport of gas and lava flow emplacement, and assess the evolving hazards. In addition to data accessibility and interpretation, managing this volcanic crisis was possible thanks to strong collaboration between the scientific institutions and civil protection agencies. The eruption presented an opportunity to tune, test and validate a variety of numerical models for hazard assessment as well as to refine and improve the delivery of information to the general public, communities living near the eruption site and decision makers. The monitoring team worked long hours during both the pre- and syn-eruptive phases for identifying low risk access areas to the eruption site and to provide a regular flow of information. This paper reviews the eruption and its associated hazards. It also provides an overview of the monitoring setup, the adopted numerical tools and communication materials disseminated to the general public regarding current exclusion zones, hazards and possible future eruptive scenarios.International Civil Aviation Organization (ICAO

    The VOL-CALPUFF model for atmospheric ash dispersal. I. Approach and physical formulation

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    We present a new modeling tool, named VOL-CALPUFF able to simulate the transient and three-dimensional transport and deposition of volcanic ash under the action of realistic meteorological and volcanological conditions throughout eruption duration. The new model derives from the CALPUFF System, a software program widely-used in environmental applications of pollutant dispersion, that describes the dispersal process both in the proximal and distal regions and also in presence of complex orography. The main novel feature of the model is its capability of coupling a Eulerian description of plume rise with a Lagrangian representation of ash dispersal described as a series of diffusing packets of particles or puffs. The model is also able to describe the multiparticle nature of the mixture as well as the tilting effects of the plume due to wind action. The dispersal dynamics and ash deposition are described by using refined orography-corrected meteorological data with a spatial resolution up to 1 km or less and a temporal step of 1 hour. The modeling approach also keeps the execution time to a few minutes on common PCs, thus making VOL-CALPUFF a possible tool for the production of ash dispersal forecasts for hazard assessment. Besides the model formulation, the paper presents the type of outcomes produced by VOL-CALPUFF, shows the effect of main model parameters on results, and also anticipates the fundamental control of atmospheric conditions on the ash dispersal processes. In the companion paper (\cite{barsotti}, this issue) a first thorough application of VOL-CALPUFF to the simulation of a weak plume at Mount Etna (Italy) is presented with the specific aim of comparing model predictions with independent observations

    Beamlike models for the analyses of curved, twisted and tapered horizontal-axis wind turbine (HAWT) blades undergoing large displacements

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    Abstract. Continuous ongoing efforts to better predict the mechanical behaviour of complex beamlike structures, such as wind turbine blades, are motivated by the need to improve their performance and reduce the costs. However, new design approaches and the increasing flexibility of such structures make their aeroelastic modelling ever more challenging. For the structural part of this modelling, the best compromise between computational efficiency and accuracy can be obtained via schematizations based on suitable beamlike elements. This paper addresses the modelling of the mechanical behaviour of beamlike structures which are curved, twisted and tapered in their unstressed state and undergo large displacements, in- and out-of-plane cross-sectional warping, and small strains. A suitable model for the problem at hand is proposed. Analytical and numerical results obtained by its application are presented and compared with results from 3D FEM analyses

    Uncertainty quantification and sensitivity analysis of volcanic columns models: results from the integral model PLUME-MoM

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    The behavior of plumes associated with explosive volcanic eruptions is complex and dependent on eruptive source parameters (e.g. exit velocity, gas fraction, temperature and grain-size distribution). It is also well known that the atmospheric environment interacts with volcanic plumes produced by explosive eruptions in a number of ways. The wind field can bend the plume but also affect atmospheric air entrainment into the column, enhancing its buoyancy and in some cases, preventing column collapse. In recent years, several numerical simulation tools and observational systems have investigated the action of eruption parameters and wind field on volcanic column height and column trajectory, revealing an important influence of these variables on plume behavior. In this study, we assess these dependencies using the integral model PLUME-MoM, whereby the continuous polydispersity of pyroclastic particles is described using a quadrature-based moment method, an innovative approach in volcanology well-suited for the description of the multiphase nature of magmatic mixtures. Application of formalized uncertainty quantification and sensitivity analysis techniques enables statistical exploration of the model, providing information on the extent to which uncertainty in the input or model parameters propagates to model output uncertainty. In particular, in the framework of the IAVCEI Commission on tephra hazard modeling inter-comparison study, PLUME-MoM is used to investigate the parameters exerting a major control on plume height, applying it to a weak plume scenario based on 26 January 2011 Shinmoe-dake eruptive conditions and a strong plume scenario based on the climatic phase of the 15 June 1991 Pinatubo eruption
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