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Mario Ridolfi e "il diamante per Lina"
Get PDFRIASSUNTO Nel venticinquesimo anniversario della morte di Mario Ridolfi, questo articolo si aggiunge ai numerosi studi in corso di pubblicazione con la specificità di dedicarsi interamente al tempio familiare dell’architetto, la residenza privata costruita per sé e per sua moglie Adelina, in località Marmore (Terni). Dopo un breve cenno biografico e professionale, questo contributo focalizza l’attenzione sugli studi preparatori dell’edificio, affettuosamente denominato dall’architetto “casa Lina” col nomignolo della moglie. Tali disegni, analizzati presso l’archivio dell’Accademia Nazionale di San Luca in Roma, permettono di comprendere l’elaborazione accurata e lo sviluppo dell’opera, concepita basandosi su una pianta stellare, nata dalla rotazione di due pentagoni. La realizzazione di questa struttura singolare fu avviata nel 1966 utilizzando materiali locali, quali la pietra sponga e il ferro battuto, elementi funzionali e decorativi caratteristici dell’opera di Mario Ridolfi durante l’intero periodo artistico denominato “ciclo delle Marmore”. Al di là dell’effettiva costruzione, avvenuta in tempi rapidi, Ridolfi continuò a ridisegnare aggiunte, integrazioni e modifiche al progetto. A “casa Lina” il maestro avrebbe trascorso gli ultimi anni di matrimonio insieme alla moglie, deceduta nel 1970, e della sua vita, terminata tragicamente nel 1984 per suicidio. SUMMARY In the twenty-fifth anniversary of Mario Ridolfi's death, this article adds to the many studies being published the specificity of devoting itself to the family temple of the architect, the residence built for himself and his wife Adelina, in Marmore (Terni). After a brief biographical and professional sketch, the paper focuses on preparatory studies of the building, known as "Casa Lina" with the nickname of Ridolfi's wife. These drawings (in the archives of the Accademia Nazionale di San Luca in Rome), allow to understand the accurate processing and development of the work, which is basically designed on a stellar plan, created by the rotation of two pentagons. The realization of this singular structure started in 1966 using local materials, such as stone and iron, decorative and functional elements characteristic of Ridolfi's work during the whole period of art called "ciclo delle Marmore". Ridolfi continued to reshape additions and changes to the project
Cicli di lavorazione automatici: i principali metodi AFR (1a parte)
No full textRIASSUNTO: Le tecniche AFR sono il principale strumento di sviluppo di sistemi CAPP generativi. Esse permettono riconoscimento ed estrazione delle feature di forma che rappresentano un pezzo, a partire dalle informazioni geometriche estratte da un file di uscita da software CAD. In questa prima rassegna vengono presentate quattro tipologie di tecniche con esempi di applicazione, in particolare: metodi di riconoscimento sintattico (par. 1), metodi basati su regole logiche (par. 2), metodi grafici (par. 3) e metodi basati su indizi (par. 4) SUMMARY: Automatic Feature Recognition (AFR) techniques are the main tool for generative CAPP systems. They allow the recognition and extraction of form features to represent a part from geometrical CAD data. In the first part of this paper four technology types are presented with application examples, particularly: syntactic recognition methods (par. 1), methods based on logic rules (par. 2), graphical methods (par. 3) and hint based methods (par. 4)
Cicli di lavorazione automatici: i principali metodi AFR (2a parte)
No full textRIASSUNTO: Le tecniche AFR sono il principale strumento di sviluppo di sistemi CAPP generativi. Esse permettono riconoscimento ed estrazione delle feature di forma che rappresentano un pezzo, a partire dalle informazioni geometriche estratte da un file di uscita da software CAD. In questa seconda ed ultima parte della rassegna vengono presentate le due tecniche AFR che sfruttano il metodo della decomposizione volumetrica basate sul guscio convesso e sulle celle e metodi ibridi derivanti dalla combinazione di tecniche di diverso tipo. Completano l’articolo considerazioni sintetiche e critiche sulla implementazione di un metodo AFR per lo sviluppo di un sistema CAPP generativo e gli sviluppi verso cui la ricerca si sta orientando. SUMMARY: Automatic Feature Recognition (AFR) is the main approach for generative CAPP systems. They allow the recognition and extraction of form features representing a part, starting from geometrical information taken from a CAD system. In this latter part of the paper two AFR techniques are presented, exploiting the volumetric decomposition based on the convex hull and on cells and hybrid methods exploiting combinations of different techniques. The paper addresses synthetic and critical considerations on the implementation of an AFR method for the development of a generative CAPP systems and future research trends
Analytic continuation in QCD-like theories at finite density and finite isospin
No full textThe method of analytic continuation is one of the most powerful tools to
circumvent the sign problem in lattice QCD. The present study is part of a
larger project which, based on the investigation of QCD-like theories which are
free of the sign problem, is aimed at testing the validity of the method of
analytic continuation and at improving its predictivity, in view of its
application to real QCD. We have shown that a considerable improvement can be
achieved if suitable functions are used to interpolate data with imaginary
chemical potential. We present results obtained in a theory free of the sign
problem such as two-color QCD at finite chemical potential
On the characterization of the compact embedding of Sobolev spaces
No full textSUMMARY For every positive regular Borel measure, possibly infinite valued, vanishing
on all sets of -capacity zero, we characterize the compactness of the
embedding W^{1,p}({\bf R}^N)\cap L^p ({\bf R}^N,\mu)\hr L^q({\bf R}^N) in
terms of the qualitative behavior of some characteristic PDE. This question is
related to the well posedness of a class of geometric inequalities involving
the torsional rigidity and the spectrum of the Dirichlet Laplacian introduced
by Polya and Szeg\"o in 1951. In particular, we prove that finite torsional
rigidity of an arbitrary domain (possibly with infinite measure), implies the
compactness of the resolvent of the Laplacian
Fractional Vortices and Lumps
No full textWe study what might be called fractional vortices, vortex configurations with
the minimum winding from the viewpoint of their topological stability, but
which are characterized by various notable substructures in the transverse
energy distribution. The fractional vortices occur in diverse Abelian or
non-Abelian generalizations of the Higgs model. The global and local features
characterizing these are studied, and we identify the two crucial ingredients
for their occurrence - the vacuum degeneracy leading to non-trivial vacuum
moduli M, and the BPS nature of the vortices. Fractional vortices are further
classified into two kinds. The first type of such vortices appear when M has
orbifold Z_n singularities; the second type occurs in systems in which the
vacuum moduli space M possesses either a deformed geometry or some singularity.
These general features are illustrated with several concrete models
Stochastic webs and quantum transport in superlattices: an introductory review
No full textSUMMARY Stochastic webs were discovered, first by Arnold for multi-dimensional
Hamiltonian systems, and later by Chernikov et al. for the low-dimensional
case. Generated by weak perturbations, they consist of thread-like regions of
chaotic dynamics in phase space. Their importance is that, in principle, they
enable transport from small energies to high energies. In this introductory
review, we concentrate on low-dimensional stochastic webs and on their
applications to quantum transport in semiconductor superlattices subject to
electric and magnetic fields. We also describe a recently-suggested
modification of the stochastic web to enhance chaotic transport through it and
we discuss its possible applications to superlattices. keywords: stochastic
webs; quantum transport; superlattices; separatrix chao
Convergence Analysis of Deflected Conditional Approximate Subgradient Methods
No full textSubgradient methods for nondifferentiable optimization benefit from deflection, i.e., defining the search direction as a combination of the previous direction and the current subgradient. In the constrained case they also benefit from projection of the search direction onto the feasible set prior to computing the steplength, that is, from the use of conditional subgradient techniques. However, combining the two techniques is not straightforward, especially if an inexact oracle is available which can only compute approximate function values and subgradients. We present a convergence analysis of several different variants, both conceptual and implementable, of approximate conditional deflected subgradient methods. Our analysis extends the available results in the literature by using the main stepsize rules presented so far while allowing deflection in a more flexible way. Furthermore, to allow for (diminishing/square summable) rules where the stepsize is tightly controlled a-priori, we propose a new class of deflection-restricted approaches where it is the deflection parameter, rather than the stepsize, which is dynamically adjusted using the "target value" of the optimization sequence. For both Polyak-type and diminishing/square summable stepsizes, we propose a "correction" of the standard formula which shows that, in the inexact case, knowledge about the error computed by the oracle (which is available in several practical applications) can be exploited in order to strengthen the convergence properties of the method. The analysis allows for several variants of the algorithm; at least one of them is likely to show numerical performances similar to these of "heavy ball" subgradient methods, popular within backpropagation approaches to train neural networks, while possessing stronger convergence properties
Applicazioni industriali dei sistemi di visione artificiale
No full textSUMMARY: The potential of artificial vision in new industrial applications and how to take advantage of university research. RIASSUNTO: L’articolo mira a dimostrare le potenzialità di applicazione dei sistemi di visione artificiale in nuovi settori, mostrando un’ampia gamma di problematiche industriali diversificate già affrontate con successo. Vengono inoltre fornite indicazioni operative per attivare una collaborazione universitaria finalizzata alla valutazione tecnico economica dei vantaggi offerti per applicazioni specifiche innovative
Scalable concurrency control in a dynamic membership
No full textSUMMARY We introduce a solution for a concurrency control problem which is frequently encountered in practice: in a dynamic system we want that the load on a centralized resource is uniformly distributed among users, offering a predictable performance as long as it is not overloaded. We propose an original solution based on probabilistic assumptions, and we comment early experimental results