IRIS - UNIRSM (Univ. degli Studi della Repubblica di San Marino)
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Mechanical behaviour of cement-bitumen treated materials containing different amounts of reclaimed asphalt
No full textCold recycling techniques have become one of the main sustainable solutions in road
construction and maintenance. The use of reclaimed asphalt (RA) as a constituent
material for bound mixtures offers two main advantages: it eliminates problems concerning
disposal and it allows natural resources to be preserved. Among the most
widespread recycled mixtures, the use of cement–bitumen-treated materials (CBTM)
for subbase courses has rapidly increased over the last 10 years. This paper deals
with the influence of RA content on the mechanical characteristics of CBTM. Several
mixtures were produced by combining different dosages of binders (cement and bituminous
emulsion) and RA contents. The behaviour of recycled mixtures was evaluated
and compared in terms of indirect tensile strength, water sensitivity and stiffness
modulus. In addition, the effects of temperature on the stiffness properties were
investigated. Experimental results showed that the RA content did not significantly
affect the compactability and the strength properties of CBTM. The presence of RA
determined an increase in mix deformability and thermodependence, but the effect
can be inhibited by increasing cement dosage. The findings offer good prospects for
increasing the use of RA and encourage administrations to employ this material as
an effective construction solution
Corsisti TFA e Nuove Tecnologie
No full textIl saggio esamina alcuni dati e ad avanza conseguenti riflessioni sulla consuetudine presentata dai corsisti TFA nell'uso di TIC nella costruzione e diffusione della conoscenza e sulla loro motivazione e volontà ad impiegarle nel loro futuro professionale. La prima parte intende rilevare la quantità e la qualità di TIC presenti nella esperienza quotidiana e personale dei corsisti. Tale rilevazione è stata effettuata attraverso la somministrazione iniziale di un questionario ad un campione significativo di iscritti ai corsi TFA dell'Università di Bologna nell'anno 2014. Le parti successive riguardano invece la raccolta delle opinioni dei corsisti, attraverso la sommistrazione di un secondo questionario, in merito alla loro motivazione e alle loro competenze nell'introduzione delle TIC all'interno della loro professione
Supplier selection: Single sourcing vs. Dual sourcing with sustainability considerations
No full textThis paper presents an integrated approach to supplier selection, which takes into account sustainability considerations and allows for the analysis of single sourcing vs. dual sourcing. A set of criteria and subcriteria are identified from the literature and used for the evaluation of the suppliers. In line with the purpose of taking into account sustainability considerations, social sustainability and environmental sustainability criteria are included in the analysis, together with service criteria which reflect the traditional criteria used to evaluate and rank suppliers. The model starts with the analysis of the singlesourcing strategy, where a single vendor (supplier #1) is available for a given supply. On the basis of the selection criteria, as well as of a fuzzy logic controller model, a score is computed for supplier #1. Such a score can be compared with the performance of supplier #2, who is taken into account when the dual sourcing strategy is pondered. The proposed model is applied to the case of an Italian company, to show its usefulness in practical cases
The GDQ method for the free vibration analysis of arbitrarily shaped laminated composite shells using a NURBS-based isogeometric approach
No full textA numerical procedure based on the Generalized Differential Quadrature (GDQ) method is presented to solve the strong form of the differential equations that govern the free vibration problem of some structural elements. The dynamic behavior of several laminated composite doubly-curved shells with arbitrary shape is investigated comparing the results achieved through different Higher-order Shear Deformation Theories (HSDTs) based on an Equivalent Single Layer (ESL) approach. The theoretical framework of the well-known Carrera Unified Formulation (CUF) represents the starting point to develop easily different higher-order models. Starting from regular domains described in principal curvilinear coordinates, a completely arbitrary shape is obtained by means of Non-Uniform Rational B-Splines (NURBS) due to the advantages shown in the well-known isogeometric analysis (IGA). The mapping technique based on the use of blending functions is illustrated to twist the original domain into the distorted one without subdividing the reference domain into sub-elements or finite element (FE). The procedure is extremely general and allows to deal with different boundary condition combinations and stacking sequences. Its validity is proven by the comparison with the results available in the literature concerning arbitrarily shaped plates or obtained through three-dimensional FE models
«Vedi dunque che il caso è molto grave» Lettere di familiari a sospettati di diserzione nella Grande Guerra: tre esempi “siciliani”
No full textL’articolo si propone di indagare il funzionamento della censura postale e dei tribunali militari durante la Grande Guerra attraverso il rapporto epistolare intercorso fra i sospettati di diserzione e i propri familiari, con particolare attenzione alle testimonianze del fondo del Tribunale Supremo Militare conservato presso l’Archivio Centrale dello Stato a Roma. Dopo una prima ricostruzione del funzionamento della censura postale militare in Italia durante gli anni del primo conflitto mondiale, viene dato risalto al dibattito storiografico circa l’uso delle lettere come fontI per la storia. Al rapporto tra censura postale e giustizia militare viene dedicata l’ultima parte dell’articolo, con particolare rilievo al caso degli accusati di diserzione. In questa sede, vengono resi noti tre testi, sinora inediti, conservati nel fondo del Tribunale Supremo Militare. Si tratta di una lettera e due cartoline, tutte spedite tra il giugno e l’agosto del 1916 da o per la Sicilia. Si è scelto di circoscrivere l’attenzione al territorio siciliano in quanto la regione, ai margini del regno d’Italia e lontana dalla linea del fuoco, è al momento al centro degli interessi di ricerca dell’autore, sulla scia di un recente filone di studi riguardante la partecipazione dell’isola alla Grande Guerra. Dal punto di vista storiografico, si tratta di fonti estremamente interessanti poiché, da una parte, testimoniano il modo di operare e le scelte della censura militare, dall'altra, ci raccontano quali fossero le emozioni, i sentimenti e la posta in gioco per i militari e le loro famiglie nel caso in cui si passasse dall'altro lato del campo come prigionieri e si fosse per questo accusati di diserzione
Different measuring methods for estimating the hydraulic conductivity on the shallow aquifer along a stretch of the Rimini coast.
No full textIsogeometric Analysis of Composite Structures Through Mapping Using Blending Functions
No full textThe Differential Quadrature (DQ) method is a numerical technique for the solution of initial and boundary value problems. It is well-known that this method has been applied to a variety of physical and engineering problems through the years. As almost any numerical approach, the DQ method can be easily used in regular domains, such as squares and rectangles. In very recent years, the authors extended this limitation introducing the Strong Formulation Finite Element Method (SFEM) which merges the advantages of DQ method and a mapping technique using serendipity elements. However, mapping through serendipity elements can lead to errors related to geometry approximation. For example, when an 8-node element is used to map an arc of circumference. This mapping is not exact except at the nodal points at the boundaries. These kind of difficulties can be avoided by using blending functions that allow exact mapping. For the sake of generality, the authors considered Non Uniform Rational Basis-Splines (NURBS) as blending functions for the nonlinear mapping of any general element into the computational space. NURBS are curves widely used in the CAD design and they are usually used for the geometric description of structural components. The aim of this study is to investigate the structural behavior of composite structures where discontinuities and curved boundaries are present. Numerically speaking the convergence, reliability and stability on the static and dynamic solutions lead by the SFEM are shown through practical applications related to civil, mechanical, aerospace and naval engineering
A General Formulation Based Based on Higher-Order Theories for the Static and Dynamic Analysis of Doubly-Curved Structures with Variable Mechanical and Geometrical Properties
No full textThe need of a specific static or dynamic behavior has led to the study of doubly-curved structures with specific mechanical configurations. In fact, this kind of structures, which are already well-known for their excellent performances, can show considerably different structural responses, in terms of both natural frequencies and stress and strain profiles along the thickness, when a mechanical property variation is taken into account. Such variations can be obtained by assuming variable engineering constants or by altering the fiber orientation, if an orthotropic fiber-reinforced composite is considered. In particular, the Variable Angle Tow placement concept allows to arrange the reinforcing fibers along curvilinear paths. In the same way, the geometric parameters are assumed variable in each point of the domain. In fact, by using the differential geometry is possible to study several structures with variable radii of curvature and variable thickness. In addition, the mechanical behavior of doubly-curved structures can be considerably different if one layer with variable properties is combined with other orthotropic plies or with a softer core. Nevertheless, the well-known first-order shell theories cannot represent correctly the mechanical behavior of such laminated composite structures. Hence, higher-order formulations have to be introduced for this aim. The validation of this approach is performed through several applications. In particular, the numerical solution obtained by using the Generalized Differential Quadrature appears to be accurate and stable
Hot recycling of reclaimed asphalt using a bio-based additive
No full textHot recycling of reclaimed asphalt (RA) has increasing interest worldwide due to economical and environmental benefits. In particular, the use of RA in place of virgin aggregates reduces of aggregate supply and disposal of RA. Moreover, the hot recycling process allows reusing the aged bitumen from the RA, implying a reduction of the required amount of new bitumen. However, the ageing process, which occurs from the production throughout the service life of the pavement, affects physical and chemical properties of bitumen, determining its hardening. For this reason, when high amounts of RA has to be reused (more than 20% by aggregate weight), the use of specific additives is strongly recommended in order to reach the desired bitumen properties and consequently to produce an asphalt concrete (AC) with high performance. This experimental project focused on the use of a bio-based additive (A) for the production of an AC for binder course with a high amount of RA. The experimental program consisted of two main phases: the first phase dealt with the mix design of three mixtures containing respectively no RA, 40% of RA, 40% of RA treated with A; the second phase aimed at producing and laying down in a trial section selected mixtures for the validation of the full-scale hot recycling process