Papers by Salvatore Di Gregorio
EGU General …, 2010
A Cellular Automata model was developed for modelling the flow of snow avalanches. The model is b... more A Cellular Automata model was developed for modelling the flow of snow avalanches. The model is based on SCIDDICA SS2, a numerical code recently developed for the simulation of subaerial and subaqueous flow-like landslides. Basically, the model ...
Cellular Automata (CA) represent a formal frame for dynamical systems, which evolve on the base o... more Cellular Automata (CA) represent a formal frame for dynamical systems, which evolve on the base of local interactions. Some types of landslide, such as debris flows, match well this requirement. The latest hexagonal release (S 3-hex) of the deterministic model SCIDDICA, specifically developed for simulating debris flows, is described. For CA simulation purposes, landslides can be viewed as a dynamical system, subdivided into elementary parts, whose state evolves exclusively as a consequence of local interactions within a spatial and temporal discretum. Space is the world of the CA, here constituted by hexagonal cells. The attributes of each cell ("substates") describe physical characteristics. For computational reasons, the natural phenomenon is "decomposed" into a number of elementary processes, whose proper composition makes up the "transition function" of the CA. By simultaneously applying this function to all the cells, the evolution of the phenomenon can be simulated in terms of modifications of the substates. SCIDDICA S 3-hex exhibits a great flexibility in modelling debris flows. With respect to the previous releases of the model, the mechanism of progressive erosion of the soil cover has been added to the transition function. Considered substates are: altitude; thickness and energy of landslide debris; depth of erodable soil cover; debris outflows. Considered elementary processes are: mobilisation triggering and effect (T 1), debris outflows (I 1), update of landslide debris thickness and energy (I 2), and energy loss (T 2). Simulations of real debris flows, occurred in Campania (Southern Italy) in May 1998 (Sarno) and December 1999 (San Martino V.C. and Cervinara), have been performed for model calibration purposes; some examples of analysis are briefly described. Possible applications of the method are: risk mapping, also based on a statistical approach; evaluating the effects of mitigation actions (e.g. stream deviations, topographic alterations, channelling, embankments, bridges, etc.) on flow development.
Cellular automata are good candidates for modelling and simulating complex dynamical systems, who... more Cellular automata are good candidates for modelling and simulating complex dynamical systems, whose evolution depends on the local interactions of their constituent parts. Many macroscopic phenomena have such features, but their complexity involves sometime the interaction of heterogeneous processes, whose composition is not immediate in a cellular automaton frame. Furthermore the managing of flows could be not trivial, because cellular automata and derived models as lattice-gas methods cannot always be applied successfully to macroscopic cases. We propose some empirical and practical rules for modelling some macroscopic phenomena with surface flows. An application to complex debris flows is exhibited together with the results of simulations of a real case.
This paper presents an efficient implementation of a well-known computational model for simulatin... more This paper presents an efficient implementation of a well-known computational model for simulating lava flows on Graphical Processing Units (GPU) using the Compute Unified Device Architecture (CUDA) interface developed by NVIDIA. GPUs are specifically designated for efficiently processing graphic datasets. However, recently, they are also being exploited for achieving exceptional computational results even for applications not directly connected with the Computer Graphics field. We here show an implementation of the SCIARA Cellular Automata model for simulating lava flows on graphic processors using CUDA. Carried out experiments show that significant performance improvements are achieved, over a factor of 100, depending on the problem size, adopted device and type of performed memory optimization, confirming how graphics hardware can represent a valid solution for the implementation for Cellular Automata models.
ABSTRACT This paper presents an efficient implementation of a well-known computational model for ... more ABSTRACT This paper presents an efficient implementation of a well-known computational model for simulating lava flows on Graphical Processing Units (GPU) using the Compute Unified Device Architecture (CUDA) interface developed by NVIDIA. GPUs are specifically designated for efficiently processing graphic datasets. However, recently, they are also being exploited for achieving exceptional computational results even for applications not directly connected with the Computer Graphics field. We here show an implementation of the SCIARA Cellular Automata model for simulating lava flows on graphic processors using CUDA. Carried out experiments show that significant performance improvements are achieved, over a factor of 100, depending on the problem size, adopted device and type of performed memory optimization, confirming how graphics hardware can represent a valid solution for the implementation for Cellular Automata models.
Advances in Intelligent Systems and Computing, 2014
FlySim is a Cellular Automata model developed for simulating infestation of olive fruit flies (Ba... more FlySim is a Cellular Automata model developed for simulating infestation of olive fruit flies (Bactrocera Oleae) on olive (Olea europaea) groves. The flies move into the groves looking for mature olives where eggs are spawn. This serious agricultural problem is mainly tackled by using chemical agents at the first signs of the infestation, but organic productions with no or few chemicals are strongly requested by the market. Oil made with infested olives is poor in quality, nor olives are suitable for selling in stores. The FlySim model simulates the diffusion of flies looking for mature olives and the growing of flies due to atmospheric conditions. Foreseeing an infestation is the best way to prevent it and to reduce the need of chemicals in agriculture. In this work we investigated the effects of temperature on olive fruit flies and resulting infestation during late spring and summer.
Parallel Computing, May 31, 1995
This paper describes CAMEL (Cellular Automata environMent for systEms modeLing), a scalable softw... more This paper describes CAMEL (Cellular Automata environMent for systEms modeLing), a scalable software environment based on the cellular automata theory implemented on a Transputer-based parallel computer. Cellular automata were originally defined as a theory to model the basic mechanisms of dynamic systems, permitting a new approach which is in many cases simpler and more efficient than the traditional approach based on partial differential equations. Today, cellular automata become more attractive because they are ...
RAIRO. Informatique théorique
Annals of Geophysics, 2011
The individuation of areas that are more likely to be affected by new events in volcanic regions ... more The individuation of areas that are more likely to be affected by new events in volcanic regions is of fundamental relevance for the mitigation of the possible consequences, both in terms of loss of human life and material properties. Here, we describe a methodology for defining flexible high-detail lava-hazard maps and a technique for the validation of the results obtained. The methodology relies on: (i) an accurate analysis of the past behavior of the volcano; (ii) a new version of the SCIARA model for lava-flow simulation (based on the macroscopic cellular automata paradigm); and (iii) high-performance parallel computing for increasing computational efficiency. The new release of the SCIARA model introduces a Bingham-like rheology as part of the minimization algorithm of the differences for the determination of outflows from a generic cell, and an improved approach to lava cooling. The method is here applied to Mount Etna, the most active volcano in Europe, and applications to landuse planning and hazard mitigation are presented.
ABSTRACT In the field of wildfire risk management the so-called burn probability maps (BPMs) are ... more ABSTRACT In the field of wildfire risk management the so-called burn probability maps (BPMs) are increasingly used with the aim of estimating the probability of each point of a landscape to be burned under certain environmental conditions. Such BPMs are computed through the explicit simulation of thousands of fires using fast and accurate simulation models. However, even adopting the most optimized simulation algorithms, the building of simulation-based BPMs for large areas results in a highly intensive computational process that makes mandatory the use of high performance computing. In this paper, General-Purpose Computation with Graphics Processing Units (GPGPU) is applied, in conjunction with a specifically devised wildfire simulation model, to the process of BPM building. Using two different GPGPU devices, the paper illustrates two different implementation strategies and discusses some numerical results obtained on a real landscape.
ABSTRACT Lahars represent one of the most destructive natural disasters as number of casualties i... more ABSTRACT Lahars represent one of the most destructive natural disasters as number of casualties in the world. Secondary lahars are very complex surface flows, which originate from the mobilization of pyroclastic deposits by exceptional heavy rainfalls. Simulation of secondary lahars could be an important tool for risk management in threatened regions. Multicomponent (macroscopic) Cellular Automata (CA) characterize a methodological approach for modelling large scale (extended for kilometers) complex phenomena, that evolve on the basis of local interactions. A preliminary three dimension CA model was developed and partially applied on a real event: the 2005 secondary lahar of Vascún Valley, Ecuador. Simulations are satisfying, a comparison is performed with the previous successful two dimensions model Titan2D, based on PDE, together with simulation results of the same event.
Csc, 2008
Cellular Automata are parallel computational models which are capable to give rise to heterogeneo... more Cellular Automata are parallel computational models which are capable to give rise to heterogeneous emergent behaviors notwithstanding simple local rules of evolution. In this review paper, a methodology for modeling complex natural systems through Macroscopic Cellular Automata is presented and applied to lava flow simulation. In particular, the 2001 Mt. Etna volcano Nicolosi (Italy) case study has been considered for model calibration, while the validation has been performed by considering further cases of study, which differ both in duration and emission rate. Parameter optimization was carried out by a Parallel Master-Slave Genetic Algorithm. Results have confirmed both the goodness of the simulation model and of the calibration algorithm. Eventually an application related to Civil Defense purposes is briefly described and proposed as a development.
Comput Geosci, 2006
... and crystallization, lava may change from a viscous fluid to a brittle solid during emplaceme... more ... and crystallization, lava may change from a viscous fluid to a brittle solid during emplacement. ... their implementation on parallel computing machines to exploit the maximum computational power ... fashion to ultimately a solid material because of the heating processes of lava flows. ...
Numerical modelling is a major challenge in the prevention of risks related to the occurrence of ... more Numerical modelling is a major challenge in the prevention of risks related to the occurrence of subaerial and subaqueous landslides. SCIDDICA-SS2 and SCIDDICA-SS2blocks are Macroscopic Cellular Automata models, developed for the simulations of combined subaerial-subaqueous flow-like landslides. SCIDDICA-SS2 was firstly validated on the 1997 subaerial -subaqueous debris flow at Lake Albano (Rome, Italy). This paper outlines the last version of the model, slightly improved and which was extended in order to simulate landslide characterized by large blocks inside the main landslide debris. The paper presents applications of the model to a completely submarine landslide, occurred between November 2007 and September 2008, in the nearshore of Bagnara Calabra town (Italy) and to the catastrophic M. Pacì rock-avalanche occurred on February 6, 1783 (Scilla, Italy). Simulation results of Bagnara Calabra submarine landslide by SCIDDICA-SS2 show a strong convergence between the real and simulated areas affected by the event. Furthermore, numerical analyses by SCIDDICA-SS2blocks demonstrate the ability of the model to simulate rock avalanches characterized by large blocks.
Fundamenta Informaticae, 2008
... Donato D'Ambrosio Department of Mathematics & High Performance Compu... more ... Donato D'Ambrosio Department of Mathematics & High Performance Computing Center University of Calabria, Rende, Italy [email protected] ... Salvatore Di Gregorio Department of Mathematics & High Performance Computing Center University of Calabria, Rende, Italy dig ...
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Papers by Salvatore Di Gregorio