Where Sun always shine...

WORKS

Three-dimensional Cone-Beam Computed Tomography ActiveX Style
    Abstract
Computed Tomography (CT) is nowadays a mature medical imaging technique which has met a huge success since its introduction in the 70s by Nobel prize Hounsfield. While the principles underlying tomography are exactly the same described by Hounsfield in his patent, during the years CT scanners have been constantly evolving by adopting faster volume scanning schemes, improved beam shaping and more efficient X-ray detectors. The end of this quest, a sort of holy grail of computed tomography, is three-dimensional Cone-Beam CT which promises the real-time volumetric reconstructions needed to fulfil the increasing demand of accurate on-line diagnostic examinations.

The tentative state of cone-beam computed tomography requires a new generation of advanced software tools to lead the research and development of proprietary reconstruction algorithms. This issue is addressed in this thesis by Strange Engine, our object-oriented visual toolkit dedicated to the housing, evaluation and simulation of cone-beam CT reconstruction tasks. By offering everything necessary for the testing of user-written reconstruction code within a modern, user-friendly environment exploiting state-of-the-art ActiveX software technologies, Strange Engine allows algorithm developers to focus on their real job, leaving all the other duties to the toolkit. The discussion includes an introduction to cone-beam tomography, the detailed specification of our software toolkit and the analysis of four different reconstruction algorithms for both simulated and real-world data.

    Download "Three-dimensional Cone-Beam Computed Tomography ActiveX Style" thesis in zipped PDF format (size about 5 MB).
 
 
Produzione e studio di Shapiro step
Shapiro steps production and study

    Abstract
Two "weekly" connected superconductor electrodes form a Josephson junction. When irradiated at rf frequencies Josephson junction current-voltage curve shows voltage plateaus known as Shapiro steps. The voltage values of Shapiro steps are quantized and depend on the rf frequency and on the physical constant "e / h" (being e = charge of the electron and h = Planck's constant).
After a brief of Superconductivity theory the author investigates Shapiro steps origin using a mathematical model of Josephson junction known as RCSJN model. The model is simulated thanks to a custom built computer program. Evidence of Shapiro steps is brought through many detailed experimental current-voltage curves of three Nb-Nb sandwich Josephson junctions. Comparison of experimental and simulated data is included.
This work was part of the ESUH experience held at the Physics Dep. of Genoa (Italy). The experience goal is to compare the Shapiro steps produced on separate Josephson junctions and to verify the equality of the steps voltage. Very high sensitivity is accomplished utilizing a DC SQUID (Superconductor QUantum Interference Device) as amperometer. Various techniques of noise reduction and flux coupling were introduced in this graduation thesis, these include: a pressure-temperature control system and a DC current superconductive transformer.
    Notes
Please note that "Produzione e studio di Shapiro step" includes an upgraded version of "Caos e giunzione Josephson".
ANSI C and early Java sources of Josephson junction simulation programs are available here.
You can request my graduation thesis at my address. Only the complete italian postscript version is available. Zipped size is about 3 MB.
 
 
Caos e giunzione Josephson
Chaos and Josephson junctions
    Abstract
Stewart-McCumber Josephson junction model is presented and analyzed. Numerical simulation is used to show various aspects of the behavior of rf-driven Josephson junctions. Evidence of chaos is brought through examination of current-voltage curves, Poincaré section, Lyapunov exponents and strange attractors.
    Notes
ANSI C and early Java sources of Josephson junction simulation programs are available here.
You can request this work at my address. Italian postscript and dvi versions are available. Zipped size is about 1 MB.
 
 
Determinazione di strutture macromolecolari tramite Multiwavelength Anomalous Diffraction
Determination of macromolecular structures via Multiwavelength Anomalous Diffraction
    Abstract
The resonance between X rays and orbital energy levels makes the photon scattering by atomic electrons anomalous. We can use this effect in X-ray crystallography to determine the structure of biological macromolecules via MAD (Multiwavelength Anomalous Diffraction) multi-frequency diffraction by synchrotron radiation.
Starting with an introduction to X-ray diffraction, the problem of reflections rephasing and the methods to solve it based on isomorphous substitution are presented. MAD diffraction is then exposed, discussing its theory and applications.
    Notes
You can request this work at my address. Only the complete italian postscript version is available. Zipped size is about 1 MB.
 
Il DC SQUID in ambito biomedicale
The DC SQUID and its applications in the biomedical field
    Abstract
This work is devoted to the superconductive device named SQUID (Superconductive QUantum Interference Device). Starting with an introduction to superconductivity and Josephson junctions theory, the quantistic interference effect, on which the DC SQUID is based on,  is exposed. Applications in the biomedical field are presented by the analysis of medical diagnostic machines, actually in the prototype stage.
 
    Notes
You can request this work at my address. Only the complete italian postscript version is available. Zipped size is about 2 MB.
 

Stefano Agostinelli - agostinellis@bigfoot.com
 
 


This page hosted by  Get your own Free Home Page





1