Search results for " Scienza"
showing 10 items of 1301 documents
Impulsive Tests on Historical Structures: The Dome of Teatro Massimo in Palermo
2016
Cultural heritage is the set of things, that having particular historical cultural and aesthetic are of public interest and constitute the wealth and civilization of a place and its people. Sharpen up methodologies aimed at safeguarding of monuments is crucial because the future may have in mind the historical past. Italy is a country that has invested heavily on its historical memory returned in large part by the historical building or the monuments. Furthermore, culture represents a fundamental indicator of the growth of the culture of a country. Consider a monitoring project of one of the most Impressive theater in the world, like “Teatro Massimo” in Palermo (Italy), means to add value t…
Analisi strutturale condotta con il BEM simmetrico in analogia al FEM
2009
Nell’articolo si presenta l’approccio agli spostamenti del Metodo Simmetrico degli Elementi di Contorno attraverso una suddivisione del corpo continuo in macroelementi denominati ebem. Attraverso questo approccio, caratterizzato da una forte condensazione delle variabili, si determina per ogni e-bem una matrice capostipite a partire dalla quale viene generata la relazione costitutiva del singolo e-bem. Quest’ultima relaziona soltanto variabili all’interfaccia tra i macroelementi, e precisamente il vettore delle trazioni pesate con il vettore degli spostamenti nodali e con il vettore delle azioni esterne. Una tale strategia è molto simile a quella seguita dal Metodo degli Elementi Finiti, ma…
Arbitrarily shaped plates analysis via Line Element-Less Method (LEM)
2018
Abstract An innovative procedure is introduced for the analysis of arbitrarily shaped thin plates with various boundary conditions and under generic transverse loading conditions. Framed into Line Element-less Method, a truly meshfree method, this novel approach yields the solution in terms of the deflection function in a straightforward manner, without resorting to any discretization, neither in the domain nor on the boundary. Specifically, expressing the deflection function through a series expansion in terms of harmonic polynomials, it is shown that the proposed method requires only the evaluation of line integrals along the boundary parametric equation. Further, minimization of appropri…
Arundo Donax particles as reinforcement for PLA based composites
2015
Aim of this work was to use particles obtained by grinding the culms of Arundo Donax used as reinforcement for PLA based composites. The influence of the content (10 wt% and 20 wt%) and size (150-300 μm and 300-500 μm) of Arundo Donax filler (ADF) on the morphology and on the properties of PLA-ADF composites was evaluated. The composites were prepared by melt compounding the PLA with ADF using a co-rotating modular twin screw extruder. For comparison, neat PLA was processed under the same conditions. Both the neat PLA and the composites were characterized by SEM, DSC, tensile and flexural measurements.
Achillis quae feruntur Astronomica et in Aratum opuscula: De universo, De Arati vita, De phaenomenorum interpretatione
2012
Si ripubblica con aggiornamenti, revisione ed ampliamento degli indici e con qualche correzione l'edizione critica edita presso l'Università di Palermo nel 1996 (Annali della Facoltà di Lettere e Filosofia dell'Università di Palermo. Studi e ricerche; 27). La presente edizione documenta come il trattato (mutilo) De universo e gli opuscoli De Arati vita, De phaenomenorum interpretatione, tramandati sotto il nome di Achille, siano opera di un unico studioso, un grammatico appassionato di astronomia e di filosofia. Vengono inoltre studiati per la prima volta estesamente i rapporti genealogici fra tutti i manoscritti acquisibili (risultano dispersi alcuni manoscritti posteriori all'invenzione d…
Graphene as a tunable resistor
2014
We present the design of a graphene-based electronically tuneable microstrip attenuator operating at a frequency of 5 GHz. The use of graphene as a variable resistor is discussed and the modelling of its electromagnetic properties at microwave frequencies is fully addressed. The design of the graphene-based attenuator is described. The structure integrates a patch of graphene, whose characteristics can range from being a fairly good conductor to a highly lossy material, depending on the applied voltage. By applying the proper voltage through two high-impedance bias lines, the surface resistivity of graphene can be modified, thereby changing the insertion loss of the microstrip attenuator.
Freedom and Redistribution
2012
In this paper we study the determinants of peopleís attitudes toward income inequality and their economic consequences. We argue that an individualís atti- tudes toward inequality depend upon the extent of freedom of choice and control over life outcomes he enjoys. We construct a two-stage empirical model where people Örst choose the level of income transfers and then their optimal level of ef- fort. We Önd that the higher the extent of an individualís free choice and control over life outcomes, the greater the probability that he supports larger income di§erences as incentives for individual e§ort. We also show that this relationship determines important consequences for the individualís w…
Stochastic differential calculus for wind-exposed structures with autoregressive continuous (ARC) filters
2008
In this paper, an alternative method to represent Gaussian stationary processes describing wind velocity fluctuations is introduced. The technique may be considered the extension to a time continuous description of the well-known discrete-time autoregressive model to generate Gaussian processes. Digital simulation of Gaussian random processes with assigned auto-correlation function is provided by means of a stochastic differential equation with time delayed terms forced by Gaussian white noise. Solution of the differential equation is a specific sample of the target Gaussian wind process, and in this paper it describes a digitally obtained record of the wind turbolence. The representation o…
Processing and characterization of highly oriented fibres of biodegradable nanocomposites
2015
Abstract Biodegradable polymeric materials are becoming day by day ever more important in packaging, agriculture, single-use cutleries and other large consumer applications. The major part of those materials is used under the form of film, i.e. subjected to elongational flow, but the main problem is that they often offer poor mechanical properties. Adding nanofillers, like Multi Walled Carbon Nanotubes (MWCNTs) may solve this problem but only if there is a full control of their orientation inside the material. Aim of this work is to investigate the processing-properties-morphology relationships for a system prepared under elongation flow of MaterBi and commercial MWCNTs. The materials were …
SHAKEDOWN ANALYSIS BY BEM
2000
In the ambit of the symmetric Galerkin boundary element formulation the statical shakedown load multiplier and the limit analysis are reformulated making use of macrozone modelling. The subdivision of the domain into macroelements makes it possible to deal with piecewise homogeneous materials of the body. For each macroelement a discretization of the boundary and a subdivision of the domain into portions called cells are performed in order to introduce the unknowns (i.e. traction and displacement discontinuities) on the boundary and material plastic laws appropriately interpolated. The weighed regularity imposed between adjacent macroelements produces algebraic operators which are symmetric…