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Catheter insertion simulation with co-registered direct volume rendering and haptic feedback
Get PDFWe have developed an experimental catheter insertion simulation system supporting head-tracked stereoscopic viewing of volumetric anatomic reconstructions registered with direct haptic 3D interaction. The system takes as input data acquired with standard medical imaging modalities and regards it as a visual and haptic environment whose parameters are interactively defined using look-up tables. The system's display, positioned like a surgical table, provide a realistic impression of looking down at the patient. Measuring head motion via a six degrees-of-freedom head tracker, good positions to observe the anatomy and identify the catheter insertion point are quickly established with simple head motion. By generating appropriate stereoscopic images and co-registering physical and virtual spaces beforehand, volumes appear at fixed physical positions and it is possible to control catheter insertion via direct interaction with a PHANToM haptic device. During the insertion procedure, the system provides perception of the effort of penetration and deviation inside the traversed tissues. Semi-transparent volumetric rendering augment the sensory feedback with the visual indication of the inserted catheter position inside the body.96-9
Analytical and interpolated cross sections into the Monte Carlo code
Get PDFThe Monte Carlo code (MC) developed by Prof. Carlo Rubbia makes use of a cross section table for each foreseen temperature. This implies either a coarse approximation of the evolution or a large memory buffer to contain all cases.
Therefore, it is important to search for the possibility of performing a local smearing starting from a low temperature during the determination of the cross sections at a higher temperature.
In this context, an algorithm has been implemented into the MC code, which calculates
analytically the cross sections of the isotopes at a given temperature T, starting from those
loaded from one of the available databases at a lower temperature T0. Finally, it is illustrated the possibility of using an interpolation procedure which allows the calculation of the cross sections valid for a wide range of temperatures
Ricostruzione e visualizzazione 3D di un cervello da acquisizioni manuali di sezioni istologiche
Get PDFIn questo lavoro presentiamo il sistema di visualizzazione da noi sviluppato per la rappresentazione tridimensionale di dati medici, ricavati da acquisizioni manuali di un insieme di sezioni parallele di un cervello di primate. Le due principali tecniche discusse sono la ricostruzione della geometria nello spazio 3D e lo studio dei metodi di visualizzazione per poterla rappresentare insieme alle strutture sottocorticali (nel nostro caso cellule neuronali di diversa tipologia). Il lavoro è organizzato come segue: nella prima sezione delineiamo le problematiche che si riscontrano in una vasta classe di esperimenti di neurofisiologia e le ragioni che ci inducono a cercare una risposta ad alcuni di tali problemi. Nella sezione seguente indichiamo i metodi e le strategie utilizzati per la ricostruzione della geometria e la visualizzazione dell'intero complesso dei dati. Successivamente indichiamo i risultati finora raggiunti, supportati da alcune immagini esemplificatrici, e infine indichiamo quali sono le possibili e più interessanti linee di sviluppo futuro, soprattutto per quanto riguarda il modello di ricostruzione delle superfici
Monitoring of a CO oxidation reactor through a grey model-based EKF observer
Get PDFOften, in real applications it is difficult to dispose of a simple, yet, representative kinetic model because of the complexity of the reactions taking place. To overcome this limitation a hybrid modelling approach is proposed for the identification of the dynamic behaviour of chemical reactors. In particular, the tools of neural network modelling have been exploited to represent the kinetic reaction data. The "neural reaction rate model" is integrated within a first principles model that constitutes the basis of a nonlinear observer (Extended Kalman Filter, EKF) for an etherogeneus gas-solid reactor where the catalytic oxidation of carbon monoxide take place. The outlined procedure shows that artificial neural networks (ANN) can be effectively used to formulate lumped reaction rates because of their capability in capturing the essential characteristics of the functional relationship among the state variables
Numerical prediction of sloshing loads in flexible tanks
Get PDFThe scope of the presentation is to review our ongoing research on the numerical modeling of sloshing in deformable tanks
Analysis and optimisation of a gas-cooled pipe for solar thermal energy production using parabolic collectors
Get PDFIn the framework of the design of a solar thermal power plant proposed by ENEA, the activity
carried out by CRS4 on the thermal-fluid-dynamic simulation of a gas-cooled pipe irradiated by a
parabolic solar collector is described in this paper.
Two methods have been adopted in parallel: a simplified one-dimensional approach and a
Computational-Fluid-Dynamics (CFD) three-dimensional approach. The first method was used to
build a tool able to give quick answers to parameters changes with an acceptable degree of
accuracy. The CFD analysis is used both to validate 1D-model results and to study in details all 3D
physical phenomena.
The multi-zone one-dimensional model developed at CRS4 is described first. The pipe is split
along its axis into a discrete number (typically 100) of sub-domains. Each sub-domain is split
further on into five different zones, corresponding to the various components of the pipe. All the
main energy-exchange mechanisms between the various parts of the pipe have been implemented,
resulting in a system of five equations for each sub-domain, solved iteratively within an EXCEL
framework.
The 3D-CFD model is then described. The model is fully parametric, allowing a quick variation of
the geometrical parameters of the system. Convection, conduction and thermal radiation heat
exchanges are solved in a coupled way. The model can give any information about field variables
of fluids and solid structures as well as all energy balances.
The two models have been used for a parametric study of the effect of the pipe diameter variation
on the system efficiency. Although not negligible differences between the two models can be
noticed concerning local energy balances, the error on the evaluation of the system efficiency is order 1%. The result of the optimization was practically the same for the two models
Web distribution of patient specific measurable arterial models
No full textIn this communication a novel framework for the segmentation, 3D reconstruction and web distribution of vessel structures is presented. Deformable models are used for segmentation, VRML and ECMA scripting are used to obtain 3D models that are not only viewable from any VRML97 enabled browser, but that also allow users to interact with the model, to navigate along the vessel lumen and to perform guided measurements of distances and angles. The segmented data are automatically converted in
VRML97 worlds hiding scripting code that enables the measurement of the geometrical parameters relevant for surgical planning directly from standard web browsers
Confronto di solutori FEM e solutori BEM per lo sloshing in contenitori
Get PDFĖ stato studiato il fenomeno di sloshing attraverso due diversi algoritmi numerici: il primo consiste in una discretizzazione con elementi finiti dell’equazione di Navier Stokes in formulazione Arbitrary Lagrangian Eulerian, è indicato nel seguito come FEM ed è descritto in [3]; il secondo è basato sulla discretizzazione delle equazioni agli integrali di contorno e delle equazioni di evoluzione della superficie libera ed è indicato come BEM e descritto in [2]. Per verificare la validità dei due codici sono stati confrontati i loro risultati con quelli presenti in letteratura, sia derivanti da altri codici numerici, sia ottenuti come risultati sperimentali. Il confronto è stato effettuato per un’ampia gamma di situazioni, in modo da studiare il comportamento dei due codici al variare delle caratteristiche della sollecitazione e delle dimensioni del dominio
A heat exchanger design for the separated window target of the EADF
Get PDFThe spallation target of the Energy Amplifier Demonstration Facility (EADF)
[1] is cooled by a liquid lead-bismuth eutectic (LBE), while the secondary
coolant is a diathermic oil. The reasons for these choices have been
extensively discussed in [2] and [3].
Here we present the design and the optimisation of a heat exchanger using
these fluids, whose additional requirements are the need of fitting into the top
of the annular downcomer section of the target and the minimisation of the
pressure losses on the LBE side, allowing the use of natural convection for
the circulation of the primary fluid.
Heat exchanger working temperatures are between 250 and 180°C in the
LBE side, and between 150 and 190°C in the oil side (cold fluid), while the
power to be removed is up to 3 MW.
We selected a bayonet-type heat exchanger, as suggested in [4] for the
primary loop of the EADF vessel, which seems to be the most appropriate
choice to satisfy all the requirements
Deux etapes pour la création dynamique d'activités Pédagogiques
Get PDFResearch on distance learning platforms aims to define models for the structure, deployment, management and use of these intelligent environments. Within this context, this paper presents a model of dynamic generation of pedagogical activities. The basic idea is that pedagogical activities are neither static nor predefined, but they can be dynamically created starting from basic documents, and presented in different ways according to the student model. The basic documents are not associated to only one activity. They are conceived to be re-used in different activities.
The paper presents in particular an implementation of a problem solving activity, generated from a two-step process, which shows how adaptability and reusability can be really effective thanks to the integration of tecnologies such as XML, DOM, XSL and the potential of the Java language by using servlets and Js