Search results for "scienza"

Use of Biochar as Filler for Biocomposite Blown Films: Structure-Processing-Properties Relationships

2021

In this work, biocomposite blown films based on poly(butylene adipate-co-terephthalate) (PBAT) as biopolymeric matrix and biochar (BC) as filler were successfully fabricated. The materials were subjected to a film-blowing process after being compounded in a twin-screw extruder. The preliminary investigations conducted on melt-mixed PBAT/BC composites allowed PBAT/BC 5% and PBAT/BC 10% to be identified as the most appropriate formulations to be processed via film blowing. The blown films exhibited mechanical performances adequate for possible application as film for packaging, agricultural, and compost bags. The addition of BC led to an improvement of the elastic modulus, still maintaining h…

Federigo Enriques matematico e filosofo

2021

Federigo Enriques ha caratterizzato la cultura italiana, nella duplice connotazione scientifica e umanistica, tra la fine dell'Ottocento e la prima metà del Novecento. Enriques ha elaborato un modello culturale incentrato sul confronto scienza e filosofia.

Giustizia sociale e dignità umana. Da individui a persona, di M.C. Nussbaum

2007

Filosofia e scienza: per una prospettiva relazionale

2009

Attraverso l''analisi di alcune fondamentali posizioni filosofiche novecentesche (Croce, Wittgenstein, Husserl, Heidegger, Rorty, Popper) si mette in rilievo le insufficienti o addirittura scorrette caratterizzazioni del discorso filosofico e di quello scientifico di per sé, e dell''uno rispetto all''altro, ragionando sulle mdoalità e sugli scopi della razionalità scientifica e di quella filosofica, e mettendone in luce l''unica matrice umana nella sua ineludibile storicità e finitezza ma insieme nella sua peculiare capacità di progresso.

Performance-Based Engineering of Wind-Excited Structures: A General Methodology

2016

The current prescriptive design philosophy that relies simply on meeting requirements stipulated in standards is shifting towards a performance-based design (PBD) approach for achieving designs that rationally meet society’s need for a truly safe built environment. Extensive research has facilitated the successful adoption of PBD in earthquake engineering, but the same cannot be said for wind engineering. Therefore, the need exists to initiate a similar effort by defining a framework that fully embraces the concepts of PBD during the design of building systems to resist severe wind events. This paper illustrates the development of such a PBD framework. In particular, a method is proposed sp…

Finite element method on fractional visco-elastic frames

2016

Viscoelastic behavior is defined by fractional operators.Quasi static FEM analysis of frames with fractional constitutive law is performed.FEM solution is decoupled into a set of fractional Kelvin Voigt elements.Proposed approach could be easily integrated in existing FEM codes. In this study the Finite Element Method (FEM) on viscoelastic frames is presented. It is assumed that the Creep function of the constituent material is of power law type, as a consequence the local constitutive law is ruled by fractional operators. The Euler Bernoulli beam and the FEM for the frames are introduced. It is shown that the whole system is ruled by a set of coupled fractional differential equations. In q…

The effect of vertical ground movement on masonry walls simulated through an elastic–plastic interphase meso-model: a case study

2019

The present paper proposes an interphase model for the simulation of damage propagation in masonry walls in the framework of a mesoscopic approach. The model is thermodynamically consistent, with constitutive relations derived from a Helmholtz free potential energy. With respect to classic interface elements, the internal stress contribute is added to the contact stresses. It is considered that damage, in the form of loss of adhesion or cohesion, can potentially take place at each of the two blocks–mortar physical interfaces. Flow rules are obtained in the framework of the Theory of Plasticity, considering bilinear domains of ‘Coulomb with tension cut-off’ type. The model aims to be a first…

BEAM ELEMENT UNDER FINITE ROTATIONS

2021

The present work focuses on the 2-D formulation of a nonlinear beam model for slender structures that can exhibit large rotations of the cross sections while remaining in the small-strain regime. Bernoulli-Euler hypothesis that plane sections remain plane and perpendicular to the deformed beam centerline is combined with a linear elastic stress-strain law. The formulation is based on the integrated form of equilibrium equations and leads to a set of three first-order differential equations for the displacements and rotation, which are numerically integrated using a special version of the shooting method. The element has been implemented into an open-source finite element code to ease comput…

In situ monitoring of moisture uptake of flax fiber reinforced composites under humid/dry conditions

2021

The use of green materials such as natural fiber-reinforced composites represents an increasingly stringent prerogative in the future planning of industrial and non-industrial production. The optimization of these materials is the main aim of the current research, focused on the evaluation of the behavior of flax fiber reinforced composites exposed to isothermal adsorption and desorption cycles, at varying the partial pressure of water vapor (P/P0). For this purpose, the moisture uptake and the morphology changes of the composite material and their constituents were in situ monitored through a measurement protocol, by using a dynamic vapor sorption (DVS) analysis, coupled with an environmen…

Effectiveness of sodium acetate treatment on the mechanical properties and morphology of natural fiber-reinforced composites

2021

This paper aims to investigate the ability of an eco-friendly and cheap treatment based on sodium acetate solutions to improve the mechanical properties of flax fiber-reinforced composites. Flax fibers were treated for 5 days (i.e., 120 h) at 25 °C with mildly alkaline solutions at 5%, 10% and 20% weight content of the sodium salt. Quasi-static tensile and flexural tests, Charpy impact tests and dynamical mechanical thermal (DMTA) tests were carried out to evaluate the mechanical properties of the resulting composites. Fourier transform infrared analysis (FTIR) was used to evaluate the chemical modification on the fibers surface due to the proposed treatment, whereas scanning electron micro…