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Algoritmi di conversione csg-rayrep e ray-rep-csg
No full textNell’ambito della realizzazione di modelli materiali di entità geometriche solide, con l’aumentare della complessità delle forme da realizzare stanno acquistando crescente importanza e la ricerca delle frontiere degli oggetti e le tecniche di riempimento automatico del loro interno. Il presente lavoro costituisce un passo nella direzione descritta e in particolare: si analizzano alcuni schemi di rappresentazione utili allo scopo CSG, B-Rep, Ray-Rep; si propone l’idea di utilizzare la Ray-Rep per generare riempimenti su una particolare tecnica di produzione, la Fused Deposition Modelling; si sviluppano degli algoritmi di conversione dallo schema CSG allo schema Ray-Rep e viceversa, per la verifica dei risultati su solidi campione
Reconstruction and web distribution of measurable arterial models
No full textIn this paper a novel framework for the segmentation, 3D reconstruction and web distribution of vessel structures specifically tailored to the assessment of abdominal aortic aneurysms for endovascular surgery planning is presented. Deformable models are used for segmentation, while VRML97 and ECMA scripting are used to obtain models that are not only viewable from any VRML97 enabled browser, but that also allow users to perform, directly from standard web browsers, guided measurements of geometrical parameters, relevant to surgical planning.79-93Pubblicat
Eeg analysis in cerebral death condition using wavelet packet decomposition
No full textThis paper proposes a methodology for extracting features from EEG in suspected brain death conditions. Those signals are usually caracterized by a low SNR and in such situations distortions introduced by skull/electrode/cable interface become very relevant. After a calibration procedure, the analysis of EEG signals was performed with a Wavelet Packet Decomposition filter, where the main component of noise are removed with soft thresholding strategy. We propose an estimate of error probability leading to the choice of wavelet basis and threshold parameters. As result, in absence of brain activity, the output of this filter produces really flat signals. However the presence of some activity can be examinated in WP time-frequency domain revealing distinctions between real brain activity, narrow band noise and artifacts.110-11
Tracking the movement of surgical tools in a virtual temporal bone dissection simulator
Get PDFIn this paper we present the current state of our research on simulation of temporal bone surgical procedures. We describe the results of tests performed on a virtual surgical training system for mid-dle ear surgery. The work is aimed to demonstrate how expert surgeons and trainees can effectively use the system for training and assessment purposes. Preliminary kinematic and dynamic analysis of simulated mastoidectomy sessions are presented. The simulation system used is characterized by a haptic component exploiting a bone-burr contact and erosion simulation model, a direct volume rendering module as well as a time-critical particle system to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.102-10
Realizzazione fisica di superfici non orientabili mediante prototipazione rapida
Get PDFIl termine Prototipazione Rapida (RP da Rapid Prototyping, conosciuta anche come Solid Freeform Fabrication – SFF) si riferisce ad un insieme di tecnologie usate per costruire prototipi di oggetti tridimensionali a partire da modelli geometrici definiti solidi ricostruiti con programmi di progettazione assistita dal calcolatore (Computer Aided Design – CAD).
Importanti applicazioni della Prototipazione Rapida si sono ampiamente diffuse negli ultimi anni in vari ambiti: si va dal campo industriale a quello biomedico a quello del design. La complessità geometrica delle forme solide da realizzare è conseguentemente aumentata e richiede lo studio sempre più accurato anche da un punto di vista matematico.
Questo documento analizza le competenze matematiche necessarie per trattare la ricostruzione di oggetti dalla geometria particolare, come ad esempio le Superfici non orientabili (Nastro di Möbius, Bottiglia di Klein) per arrivare alla definizione di una loro parametrizzazione utile per la costruzione di modelli solidi stampabili direttamente con tecnica RP. In particolare, sono trattati i problemi legati alla generazione degli spessori necessari alla realizzazione fisica
Thermal and mechanical analyses of the LHC injection beam stopper (TDI)
No full textIn this report we present the results of the analyses performed in the frame of the contract K777/SL. The object of the work is the study of the mechanical behavior of beams obstacles due to the interaction with the high energy particle beam of the new Large Hadron Collider (LHC). This includes several numerical analyses of the mechanical behavior of the TDI beam stopper under normal operating conditions
Adaptive techniques for real–time haptic and visual simulation of bone dissection
Get PDFBone dissection is an important component of many surgical procedures. In this paper we discuss adaptive techniques for providing real-time haptic and visual feedback during a virtual bone dissection simulation. The simulator is being developed as a component of a training system for temporal bone surgery. We harness the difference in complexity and frequency requirements of the visual and haptic simulations by modeling the system as a collection of loosely coupled concurrent components. The haptic component exploits a multi-resolution representation of the first two moments of the bone characteristic function to rapidly compute contact forces and determine bone erosion. The visual component uses a time-critical particle system evolution method to simulate secondary visual effects, such as bone debris accumulation, blooding, irrigation, and suction.102-10
Using compact GML to deploy interactive maps on mobile devices
Get PDFAs users get connected with new-generation smart programmable phones and Personal Digital Assistants, they look for geographic information and location-aware services. In such a scenario, developers need infrastructures and standards in order to provide geographic data and cartographic tools to a wide set of applications and small mobile devices. GIS market offers a rich set of powerful tools for geographic information management, but a simple and lightweight protocol to easily add cartographic functionalities
to mobile applications is still missing. This paper presents the compact Geographic Markup Language (cGML), a custom version of GML tailored for mobile devices. By using small tags, server side pre-projected and pre-scaled coordinates, it allows development and deployment of map-based software for mobile phones and PDAs with strong constraints on connection, CPU and memory
A multi modal interface for a visually impaired pupils educational environment
Get PDFThe aim of this paper is to describe a multi modal user interface integrated within an architecture allowing visually impaired pupils and sighted people to work on the same station. This architecture is developed to face the problem of the inclusion of visually impaired pupils in mainstream education. The system is able to display the same original multi-media content converted in different ways on screen, Braille terminal and vocal synthesizers. It accepts various interactions from keyboard, Braille bar and mouse. Both blind and sighted users can manage the same tools, cooperate together on the same content, and thus perform the same activities. Blind pupils may be assisted by sighted teachers or tutors that don’t know how to read Braille characters