CRS4 Report
URI permanente per questa collection
Può trattarsi di un rapporto finale, rapporto tecnico, rapporto di ricerca, ecc.
Sfogliare
Mostra il contenuto di CRS4 Report per Data di pubblicazione
Ora in mostra 1 - 20 di 238
Risultati per pagina
Opzioni di ordinamento
- ItemTecniche di visualizzazione volumetrica di carotaggi(1997) Gobbetti, Enrico; Pili, Piero; Scateni, Riccardo
- ItemA comparative study on modular visualization environments(1997-10) Gobbetti, Enrico; Leone, Andrea O.Modular Visualization Environment (MVE) systems constitute a particular class of Visualization Packages. They are not visualization programs, but rather environments to build visualization applications, accordingly to specific needs of data representation. It is now clear that MVE belong to the class of general purpose Visualization Packages, because this is the main property that characterize them. From the end-user point of view, MVE are extemely versatile and flexible. In many cases, setting up a personalized representation of data simply consists in interconnecting in a network a number of pre-existing modules with atomic functionality, creating the specific visualization pipeline that ends with the rendering of the data. The longer is the list of available modules, the bigger is the number of different visualization applications the user can build in the MVE. The following MVEs are reviewed in this document: Application Visualization System (AVS), by Advanced Visual Systems Inc., Data Explorer, by IBM Inc., and IRIS Explorer, by NAG Ltd.
- ItemSWEET - User manual (version 2.0)(1997-10) Corti, S.; Marrocu, Marino; Paglieri, Luca; Trotta, Rosa LoredanaSWEET (Shallow Water Equations Evolving in Time) is a code for the solution of the 2D de Saint Venant equations, written in their conservative form. The code adopts a Finite Differences scheme to advance in time, with a fractional step procedure. The space discretization is realized through Finite Elements, with a linear representation of the water elevation and a quadratic representation of the unit- width discharge. In this document, the physical model and the numerical schemes used for solving the resulting equations are extensively described. The accuracy of the scheme is verified in different test cases. The sequential algorithm has been ported in the parallel computing framework by using the domain decomposition approach. The Schwarz algorithm has been added to the scheme for preconditioning the iterative solution of the elliptic equation modeling the dynamics of the elevation of the water level. The performance of the parallel code are evaluated on a large size computational test case. The structure of the code is explained by a description of the role of each sub- routine and by a flowchart of the program. The input and output files are described in detail, as they constitute the user interface of the code. Both input and output files have a simple structure, and any effort has been made to simplify the procedure of the input setup for the parallel code, and to manage the output results. The PVM message passing library has been used to perform the communications in the parallel version of SWEET. A short introduction to PVM is added at the end of the present report. The SWEET package is the results of a joint work between CRS4 and Enel - Polo Idraulico e Strutturale. The authors of this document kindly acknowledge the valuable contributions of Vincenzo Pennati, from Enel - Polo Idraulico e Strutturale, and of Luca Formaggia, Alfio Quarteroni and Alan Scheinine, from CRS4. This manual is an extension and revision of the SWEET User Manual Version 1.0, 1996. The author of the former document, as well as of the largest part of the SWEET code, is Davide Ambrosi, currently at Politecnico di Torino. To him, not only our sincere thank is due, but mainly the recognizance that SWEET is and will remain a work of his.
- ItemA comparative study on binary scientific data formats(1997-10) Leone, Andrea O.; Gobbetti, EnricoIn this technical report a set of binary scientific data formats are examined. They will be presented by examining their main functionally and features.
- ItemTVR: un visualizzatore volumetrico ad alte prestazioni basato su OpenGL 1.0(1997-11) Zorcolo, Antonio; Pili, Piero; Gobbetti, EnricoRitenendo che uno strumento di questo tipo sia di grande utilità nella pianificazione degli interventi in campo medicale, si è realizzato un sistema di visualizzazione stereoscopica di dati medici volumetrici con tracciamento della posizione dell’osservatore, che consente sia la possibilità di trovare nel modo più naturale (un semplice spostamento del capo) la posizione più idonea per osservare la patologia che la piena comprensione della struttura tridimensionale della patologia stessa. L’utilità dello strumento è accresciuta dalla possibilità, offerta dalla collimazione dello spazio virtuale del visualizzatore con quello fisico dell’osservatore, di manipolare direttamente il volume virtuale utilizzando le mani come sul volume reale. In questo rapporto viene descritta la struttura del visualizzatore, denominato TVR, e analizzate in dettaglio le principali scelte implementative. I primi capitoli presentano i pesanti vincoli a quali s’è dovuto sottostare mentre i capitoli successivi illustrano le soluzioni adottate per soddisfarli. Negli ultimi capitoli sono riportate infine le prestazioni raggiunte e gli obiettivi futuri.
- ItemA modular approach to the Korba aquifer seawater intrusion study, 1, GIS field data analysis(1998) Giacomelli, Andrea; Khlaifi, Ihsen; Tarhouni, Jamila; Paniconi, ClaudioSeawater intrusion is an important environmental problem in the coastal aquifers of many Mediterranean countries. In the 438 km2 Korba aquifer in eastern Tunisia, a large increase in the number of pumping wells for irrigation purposes since the 1960s has resulted in a lowering to below sea level of the water table in several observation piezometers, and in a consequent deterioration of the water quality. Several remediation scenarios are being considered for this region, including rationalization and control of water pumping from the wells, artificial recharge of the aquifer and construction of small dams to serve as an alternative source of irrigation water. In order to investigate the impact of these measures on the aquifer water quality, a GIS-based modeling study is being undertaken. The available data set comprises a number of layers of geographical information, giving a complete hy-drogeological characterization of the region, and time series of chemical and hydrologic variables acquired during several ground sampling campaigns performed in the last thirty years. The GIS is used to organize this heterogeneous data structure and to control the data flow through various phases of the work, i.e. the pre-processing of input data for the model, the interpretation of model outputs, and the calibration of the model itself. The GIS serves also as a support tool in the genera-tion of the 3-D computational grid used in the numerical simulations. In addition to describing the data structure and the organization of the system, the paper illustrates also the implementation of a simple recharge optimization scenario.
- ItemIndustrial burner premixed combustion simulation. ENEA test case: HOT(1998) Murgia, GiovanniEvery industrial combustion simulation model has to be tested against standard experimental data. This work presents a comparison between calculated and experimental data of a lean premixed combustion flow with the aim of validating the Turbulent Flame Closure combustion model. The experimental results, relative to the fluid-mechanics and chemical characterization of a Dry Low NOx natural gas premixed burner working at atmospheric pressure designed by Nuovo Pignone, were carried out by ENEA. The study regards also thermal and chemical in-flame measures, to have a complete knowledge of the combustion phenomenon. The simulation has been performed by using TANIT, a FORTRAN code suitable for simulating combustion flows for gas turbines applications.
- ItemDesign and optimisation of a liquid metal spallation target for the energy amplifier prototype(1998) Maciocco, Luca; Bellucci, Valter; Buono, Stefano; Fotia, Giorgio; Moreau, Vincent; Mulas, Marco; Siddi, Giuliana; Sorrentino, LucaThe thermo-fluid-dynamic and structural analysis of the spallation target for the Energy Amplifier [1] (EA) is presented. The sensitivity of the system to the geometrical and physical parameters has been analysed through extensive numerical thermo-fluid-dynamic (TFD) simulations performed with the Star-CD commercial code [2]. Starting from the results obtained with the fluid dynamic analysis, a linear structural analysis of the window-pipe system has been performed with the MSC/Nastran finite-elements code [3]. The result of this work is a set of design guidelines for the final sizing of the target.
- ItemA distributed heterogeneous image server(1998) Loddo, Sergio; Brelstaff, Gavin; Zanetti, GianluigiDigital image transmission is now ubiquitous across computer networks and thus there is increasing pressure to allow access to medical image data at sites remote from PACS locations. In fact, it may soon make economic sense to outsource medical image services - to dedicated service providers at geographical locations outside of the traditional radiology department or HIS’s. The technical challenge faced by system developers is to produce client-Viewer/server-PACS configurations that can realistically span the network. In particular, the systems must provide the performance usually expected by client medics and it must be flexible to the needs of the service providers. At CRS4 - BioMedical Applications - we are integrating various technologies derived from the www-intranet field, and object-oriented middleware to prototype technological solutions that address both the issues of performance and flexibility. These are discussed in turn below; then we provide an overview of our system.
- ItemLand planning through GIS, RS and multicriteria decision analysis. A case study in Sardinia(1998) Manca, Germana; De Montis, A.During the last few years researchers and environmental planners have carried on their preliminary studies following an interdisciplinary approach. One of the main issues in this approach is the sustainability of economic development. As a matter of fact, the importance of the studies related to the distribution and the limits of natural resources is widely recognized. This can be accomplished more easily than in present by the use of extremely powerful computer application. The purpose of this contribution is to demonstrate the usefulness of an integrated approach of the GIS and of the RS to planning in complex problems of decision making. Many GIS applications are suited to the input of remote sensing and the integration of these techniques is now accepted in landscape planning. By means of GIS and RS, environmental information can be integrated with administrative, political, social and economic data. GIS, RS and fuzzy logic techniques are used to assist environmental compatibility studies and decision making
- ItemSviluppo di un codice per la previsione delle proprieta di fouling e slagging di carboni(1998) Murgia, Giovanni; Muscas, M.; D'Aguanno, BrunoQuesto documento costituisce la relazione tecnica finale del contratto Servizio per lo sviluppo di un codice per la previsione delle proprietà di fouling e slagging di carboni, Contratto d'appalto nr. 44AV0671, stipulato tra il CRS4 e l'ENEL-CRT. In esso viene inizialmente descritto il modello fisico-matematico su cui è basato l'algoritmo per la descrizione delle caratteristiche delle ceneri volatili ottenute dalla combustione di particelle di una data specie di carbone. Carbone che, a sua volta, è descritto da un insieme di dati sperimentali che vanno dai dati ASTM (American Society for Testing and Materials) ai molto più dettagliati dati CCSEM (Computer Controlled Scanning Electron Microscopy). Nella seconda parte del documento viene presentato l'algoritmo di calcolo e lo schema generale del codice, scritto in Fortran 90, che implementa un tale algoritmo. Il codice denominato CHARCO è il deliverable principale del contratto di cui sopra. Successivamente è presentata una descrizione dettagliata del codice numerico, delle strutture dei dati di input e output, e del suo utilizzo. Di ogni Subroutine viene data un'esplicita descrizione del suo ruolo con frequenti richiami alla parte modellistica, e del suo flusso di dati in input/output. Nella sezione dei risultati sono presentati alcuni degli output che è possibile ottenere dall'esecuzione del codice CHARCO. Sono riportati esempi di risultati ottenuti a partire da input sperimentali caratterizzanti il carbone Ashland. Tali input sono stati forniti dall'ENEL-CRT stesso. Un'interpretazione critica dei risultati è anch'essa presentata. Nella sezione riguardante gli sviluppi futuri viene brevemente descritta l'estensione modellistica e algoritmica necessaria per la descrizione dei processi di accrescimento dei depositi sui fasci tubieri scambiatori di calore. Tale estensione si configura come il deliverable significante, sia in termini interpretativi che di ritorno economico, del progetto di ricerca avente come oggetto la comprensione della tendenza al fouling/slagging delle ceneri ottenute dalla combustione di carboni polverizzati. Notiamo che una tale estensione costituisce la base di partenza per la produzione di pacchetti software per il controllo degli stessi fenomeni nei casi della combustione di miscele di carbone, di miscele con RDF (Refuse Derived Fuels), e nella gassificazione. Nella sezione finale sono riportate le conclusioni e un breve sommario. Al presente documento è allegato il codice CHARCO.
- ItemCoercive domain decomposition algorithms for advection-diffusion equations and systems(1998) Alonso, Ana; Trotta, Rosa Loredana; Valli, AlbertoTwo families of non-overlapping coercive domain decomposition methods are proposed for the numerical approximation of advection dominated advection-diffusion equations and systems. Convergence is proven for both the continuous and the discrete problem. The rate of convergence of the first method is shown to be independent of the number of degrees of freedom. Several numerical results are presented, showing the efficiency and robustness of the proposed iterative algorithms.
- ItemDBMMS: DataBase MultiMedia System: un sistema per la gestione di contenuti culturali su internet(1998) Paddeu, Gavino; Stara, Enrico; Tuveri, FrancoQuesto documento descrive le modalità di attuazione e di realizzazione di alcuni tools per la gestione e l’organizzazione di informazioni aggregate nell’ambito di applicazioni su Internet caratterizzate dal possedere natura multimediale. Il sistema software, descritto in questo documento, cerca di offrire all’utente, in maniera assolutamente trasparente, la capacità di navigare tra informazioni logicamente correlate ed organizzate. Tali informazioni saranno strutturate in maniera da fornire una chiave di lettura logica attraverso raccolte di dati idealmente guidate e mirate. Le informazioni andranno a costituire un unico archivio organizzato secondo particolari criteri, utili per rendere più semplice e logica la fruizione delle risorse che saranno rese disponibili via Web.
- ItemDemonstration: dynamic-HTML paper metaphors(1998) Brelstaff, Gavin; Chessa, FrancescaWe demonstrate prototypes that sustain the paper metaphor in two new on-line scenarios: (1) reading annotated works of foreign literature, and (2) paperless medical reporting. See [Brelstaff & Chessa, “Sustaining the paper metaphor with Dynamic- HTML”, submitted as a short paper to HCI’98] for further detail.
- ItemDicom image handling for medical analysis and the ViVa project(1998) Donizelli, Marco; Giachetti, Andrea; Scheinine, AlanThe aim of this work was to build the basic system for medical image retrieval and elaboration suitable for the ViVa Project, aiming at building, from clinical data, virtual vascular systems where also blood flow fields can be simulated and analysed.
- ItemSustaining the paper metaphor with dynamic HTML(1998) Brelstaff, Gavin; Chessa, FrancescaWe describe prototypes that sustain the paper metaphor in two new on-line scenarios: (1) reading annotated works of foreign literature, and (2) paperless medical reporting [Brelstaff & Chessa, “D-HTML paper metaphors”, submitted to Demo’s at HCI’98].
- ItemLeveraging internet-98 technology for computer healthcare networks: to its limits and its limitations(1998) Brelstaff, GavinTo what extent can current Internet technology be leveraged to fulfill the vision of the electronic patient record (EPR) as a multimedia object and the healthcare information system as a secure distributed computing network? We explore provision of reliable, secure, intuitive, and inexpensive medical Intranets through simple scripting and configuration – avoiding the need for large programming teams. By prototyping the EPR as a secure newsgroup we demonstrate the feasibility of a basic workflow system that: preserves a signed-paper style visibility of patient data at all times; enriches presentation with multimedia online image exam viewing and user controlled animation; whilst protecting confidential patient data via encrypted data transmission, digital signatures, and authenticated user-access control. In the process several limitation of this technology are uncovered.
- ItemNumerical simulations of a premixed experimental combustor(1998) Barbato, MaurizioThis report presents results of computational simulations of a premixed combustion flow in an experimental plane combustor. In Chapter 1 a brief description of the test case and of flow main characteristics are given. Results obtained from computations are compared each others and with experimental results in Chapter 2. Finally, results are discussed and conclusions on results quality are drawn.
- ItemCoercive multidomain algorithms for incompressible fluid dynamics(1998) Trotta, Rosa LoredanaThe aim of this work is to present a new multidomain algorithm for the solution of Navier-Stokes equations. This is obtained by applying suitable domain decomposition methods, introduced for advection dominated advection-diffusion equations, in the context of fluid dynamics equations. The main novelty of out method [1] resides in the fact that we don't care about the local direction of the advective field on the interface Γ (as proposed in [2]), but we only need that the boundary value problems in each subdomain along the subdomain iterations are associated to a suitable coercive bilinear form. The extention of these methods to the resolution of the Navier-Stokes equations, has been obtained by facing the numerical solution focusing on the advection-diffusion phenomena, trying to circumvent the difficulties arising form the incompressibility constraint. This can be done using suitable fractional step methods, where the pressure does not play anymore the role of a Lagrange multiplier associated to the constraint. The method used is an incremental projection method, based on a reduced number of equations with respect to the classical projection algorithms, and, in particular, can be considered as a stabilization method. This choice allows the use of equal-order interpolation spaces, and therefore yields a considerable computational saving. The algorithms obtained are suited for parallel implementation.
- ItemMesh adaption strategies for shallow water flow(1998) Marrocu, Marino; Ambrosi, DavideIn this paper it is shown how themesh adaption technique can be exploited for the numerical simulation of shallow water flow. The shallow water equations are numerically approximated by the Galerkin finite element method, using linear elements for the elevation field and quadratic elements for the unit-width discharge field; the time advancing scheme is of fractional–step type. The standard mesh refinement technique is coupled with the numerical solver; movement and elimination of nodes of the initial triangulation is not allowed. Two error indicators are discussed and applied in the numerical examples. The conclusion focuses the relevant advantages that are obtained applying this adaptive approach by considering specific test cases of steady and unsteady flows.