Una metodologia multivariabile per la calibrazione di alcuni parametri idrogeologici Portoscuso (Sardegna)

Nella presente nota si mostra l’applicazione di una metodologia di calibrazione per la valutazione di alcuni parametri idrogeologici. La metodologia si basa su un approccio multivariabile ed è sviluppata attraverso l’integrazione del GIS con modelli numerici. I dati, implementati in un GIS, costituiscono l’input di un modello tridimensionale agli elementi finiti (CODESA 3D) per la valutazione di fenomeni di trasporto di inquinanti in falda. La metodologia permette, variando opportunamente alcuni parametri del sistema attraverso l’analisi comparata degli scenari simulati, di determinare le configurazioni che meglio riproducono il sistema reale. In particolare si considera un algoritmo di ottimizzazione, implementato in Arcview, che minimizza gli scarti tra le misure campionate e quelle simulate. L’insieme delle configurazioni in grado di riprodurre il comportamento del sistema è poi discusso in termini probabilistico−statistici. Obiettivo del presente lavoro è, oltre alla parametrizzazione del sistema fisico in studio, l’implementazione all’interno del GIS di una metodologia automatica di gestione e analisi dei dati simulati. Il sito su cui viene testata la procedura è un settore della piana di Portoscuso (Sardegna Sud Occidentale) inquinata da residui inorganici provenienti da industrie metallurgiche e chimiche.An extensive quality assessment of the data has been carried out to characterize the area overlying the aquifer system of Portoscuso (Southern Sardinia). In this context we set up a geographical information system and applied a environmental model to study contaminant migration. A critical point of our study is the data crossing between the measured data and the simulated ones. In this context a methodology for testing the accuracy of the model and to calibrate hydro−geological parameters has been implemented in the GIS.715-72

Nuove prospettive del GIS nella gestione dell'ambiente: l'approccio Datacrossing

2006-11-22Sardegna Ricerche, Edificio 2, Località Piscinamanna 09010 Pula (CA) - ItaliaGis Day 2006: dal Gis al Geo-We

The data-crossing approach to locate point source pollution. The Portoscuso Case (Sardinia)

È oggi comunemente riconosciuta l’esigenza di disporre di metodi e tecniche per la tutela e la gestione ottimale delle risorse idriche e per la valutazione dell’impatto ambientale dovuto a rischi naturali e alla presenza di sostanze contaminanti nei bacini idrologici e nelle acque sotterranee. Individuare le fonti localizzate e le modalità di immissione di inquinanti negli acquiferi, in riferimento a cause e tempi con cui l’inquinamento si è prodotto, è estremamente complesso. In questo lavoro viene descritto un sistema informatico integrato di modellizzazione formato da tecnologie GIS, generatori di griglia, simulatori numerici, e visualizzatori al fine di indagare l’impatto sulla qualità dell’acqua di fonti di inquinamento localizzate e diffuse e quantificare l’incertezza nell’applicazione del modello idrologico. La procedura permette, variando la posizione delle fonti di immissione degli inquinanti, di simulare le configurazioni che meglio riproducono le situazioni reali. Possono essere ipotizzate congiuntamente più fonti di immissione contemporanee supponendo diverse leggi di immissione. In particolare la procedura è stata applicata ad un caso di studio reale, per analizzare e incrociare i campi di inquinamento simulati coi valori di inquinamento misurati in situ al fine di individuare i punti possibili d’immissione dell’inquinante e il relativo tempo di permanenza. L’insieme delle configurazioni in grado di riprodurre il comportamento del sistema è stato poi discusso in termini probabilistici e statistici. Il sito in esame è un settore della piana di Portoscuso (Sardegna Sud Occidentale) inquinata da residui inorganici provenienti da industrie metallurgiche e chimiche.Tools and methodologies for optimal water resources management and for environmental impact analysis are needed in order to evaluate natural hazards, presence of contaminant sources in hydrological and groundwater basins etc.. Finding the location of point source pollution and understanding the dynamics of groundwater degradation, considering also the causes and the time of its occurrence, can be extremely complex. In this work, an integrated software system has been developed, herein described. This is a suit of partly in-house developed modules composed of GIS technologies, mesh generators, and hydrological and pre/post processing codes designed to predict the impact of a point source of pollution and to quantify the uncertainty due to the model application. Moreover the computational system has been personalized, for a case study, to integrate simulated contamination fields with in situ measurements to identify the location of point source pollution and the time of the spill. The procedure enable the user to identify the simulated scenario closest to the observed one. A probabilistic approach will be then performed to analyse the results. The resulting methodology was applied to the case of the Portoscuso Plain (South-West Sardinia) threatened by inorganic residuals from the industrial zone of Portoscuso

Database distribuiti al servizio di sistemi ambientali avanzati: l'esperienza Datacrossing

2006-11-28Sardegna Ricerche, Edificio 2, Località Piscinamanna 09010 Pula (CA) - ItaliaKick-off Meeting del Progetto GRIDA

Timing with the Galileo Open Service

The article addresses UTC dissemination through Galileo Open Service and describes the Galileo Open Service Key Performance Indicators related to timing

Localization and tracking in known large environments using portable real-time 3D sensors

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An original FE modelling of a longitudinal multi-passes seam welding

Abstract Both finite element and analytical methods for simulation of welding are essential to predict residual stress and distortions of welded components. Best FE modelling is obtained by using solid elements for thermo-structural simulation with high computational cost. In this contest, an equivalent modelling of plates based on shell elements is proposed in order to streamline the simulations. The equivalent model is composed of n levels of shell elements, centered on the weld seam, in order to evaluate rotations and translations typical of a multi-pass weld. There are as many levels as the number of the weld passes that compose the seam. The interconnection between the n shell levels is realized by rigid beam elements. The latter ones are connected to shell elements by constraint equations. Solid brick models of the plates are used as a benchmark for the equivalent models in thermal and mechanical simulations. The equivalent modelling is in good agreement with solid results, showing a strong decrease of computational burden, enabling the simulation of large welded models in operative conditions

structural health monitoring algorithm application to a powerboat model impacting on water surface

Abstract In naval field, live monitoring of local strains and displacements in the hull is the basis for dynamic studies such as checking the design limits, sea-keeping tests in smooth and rough seas, fatigue life estimation and damage detection. Vessels sailing on water are subject to impulsive loadings and local deformations; in these conditions the damage detection in real time becomes crucial. In this paper, a numerical methodology is proposed to measure the deformation of the whole structure of a powerboat entering the water free surface starting from local strain measurements, obtained numerically in a FE simulation. A modal decomposition approach has been used to reconstruct the structural response of the whole boat body. The reconstruction algorithm is calibrated for this study by means of the normalized modal strains matrix obtained through a FEA. A transient FE analysis is implemented to generate local strain signals from virtual sensors. In this analysis hydrodynamic loading resulting from well-known models are applied. The positioning and number of the virtual reference and control sensors are investigated. Virtual control sensors are utilized to compare strains with respect to the reconstructed quantities. Subsequently, the structural health monitoring algorithm has been applied to the powerboat model with a localized damage on the structure. The results reported in the paper reveal the capability of the method to detect the damage in real time

NLP-based Metadata Extraction for Legal Text Consolidation

The paper describes a system for the automatic consolidation of Italian legislative texts to be used as a support of an editorial consolidating activity and dealing with the following typology of textual amendments: repeal, substitution and integration. The focus of the paper is on the semantic analysis of the textual amendment provisions and the formalized representation of the amendments in terms of metadata. The proposed approach to consolidation is metadata- oriented and based on Natural Language Processing (NLP) techniques: we use XML-based standards for metadata annotation of legislative acts and a flexible NLP architecture for extracting metadata from parsed texts. An evaluation of achieved results is also provided

Implementation of a Comprehensive Mathematical Model for Tilt-Rotor Real-Time Flight Simulation

This paper aims at describing the effort performed by the joint research group of Politecnico di Torino and ZHAW (Zurich University of Applied Sciences) in achieving a novel implementation of a mathematical model for real-time flight simulation of tilt-rotors and tilt-wings aircraft. The focus is on the description of the current stage of the project, the achievements of the first version of the model, on-going improvements and future developments. The first part of the work describes the initial development of the overall simulation model: relying on several NASA reports on the Generic Tilt Rotor Simulator (GTRS), the mathematical model is revised and the rotor dynamic model is improved in order to enhance computational performance. In particular, the model uses the conventional mathematical formulation for non-dynamic inflow modelling based on Blade Element Momentum Theory. A novel but simple numerical method is used to ensure the convergence of the non-linear equation in every tested condition. The resulting simulation model and its development and implementation in the MATLAB/Simulink® environment is described. The second part of the work deals with the integration of the model in the ZHAW Research and Didactics Simulator (ReDSim), the replacement of the pilot controls by the introduction of a center stick and the corresponding adjustment of the force-feel system to suitable values for the tilt-rotor model. Subsequently, several pilot tests are carried out and preliminary feedbacks about the overall behaviour of the system are collected. Limits and weaknesses of the first release of the model are investigated and future necessary improvements are assessed, such as the development of a novel generic prop-rotor mathematical model. The third part introduces the novel multi-purpose rotor mathematical model which was developed to improve the overall tilt-rotor simulation model. The multi-purpose rotor model implements non-approximated flapping dynamics and inflow dynamic based on Pitt-Peters formulation. The validation of the novel rotor model is carried out with available data of both the XV-15 Research Aircraft and the UH-60 Helicopter