Papers by Nicola Mastronardi
Journal of Computational and Applied Mathematics, 2012
The problem of reconstructing signals and images from degraded ones is considered in this paper. ... more The problem of reconstructing signals and images from degraded ones is considered in this paper. The latter problem is formulated as a linear system whose coefficient matrix models the unknown point spread function and the right hand side represents the observed image. Moreover, the coefficient matrix is very ill-conditioned, requiring an additional regularization term. Different boundary conditions can be proposed. In this paper antireflective boundary conditions are considered. Since both sides of the linear system have uncertainties and the coefficient matrix is highly structured, the Regularized Structured Total Least Squares approach seems to be the more appropriate one to compute an approximation of the true signal/image. With the latter approach the original problem is formulated as an highly nonconvex one, and seldom the global minimum can be computed. It is shown that Regularized Structured Total Least Squares problems for antireflective boundary conditions can be decomposed into single variable subproblems by discrete sine transform. Such subproblems are then transformed into one-dimensional unimodal real-valued minimization problems which can be solved globally. Some numerical examples show the effectiveness of the proposed approach.
Drafts by Nicola Mastronardi
ITALIA E ROMA: LA MONETA DELLA RICONCILIAZIONE, 2023
"ITALIA" PRIMA DEL MEDIOEVO? Nel 68 a.C. due magistrati monetari rimasti pressocché anonimi nell... more "ITALIA" PRIMA DEL MEDIOEVO? Nel 68 a.C. due magistrati monetari rimasti pressocché anonimi nella grande storia di Roma decidono di coniare un denario d'argento per il quale dovrebbero avere invece un posto d'onore nella storia d'Italia. Tali Quintus Fufius Calenus e Mucius Cordus fissano su un piccolo tondo in argento la rappresentazione di un fondamentale momento storico nei rapporti tra Roma e Italia. Due donne, una dotata di cornucopia, l'altra di scettro e spada, compiono un gesto di unione e riconciliazione sotto la protezione di altrettante divinità: Honos et Virtus.
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Papers by Nicola Mastronardi
Drafts by Nicola Mastronardi