1,356,736 research outputs found
Flexibility and Security in Temporary Work: A Comparative and European Debate. WP C.S.D.L.E. "Massimo D'Antona" .INT - 56/200
No full textPreface. ....The University of Florence acted as the coordinator of a research project called 'La dimensione europea ed internazionale del diritto del lavoro: un laboratorio fiorentino di ricerca', launched by Professor Silvana Sciarra in collaboration with the Universities of Boston, Cambridge, Catania, Eichstatt Ingolstadt, EUI, Lyon II, Madrid Complutense, and Venezia....To date, it has given rise to several international collaborations. One of the sub-headings of the project dealt with labour market reforms in Member States of the EU, linked with the European employment strategy. Following a workshop held at the Law Faculty of the University of Cambridge on 16 and 17 March 2007 entitled 'Flexibility and Security in Temporary Work - A Comparative and European Debate', the topic selected by some members of the research group as a case study was 'Fixed Term Contracts'. The papers contained in this document reflect the approach adopted during the workshop. They focus on certain common legal features of fixed term contracts, but also rely on statistical figures where relevant. A 'model paper' was circulated in order to acquire homogeneous information from all of the countries involved in this project. The publication on-line of what should be considered as 'work in progress' is meant to stimulate comments and attract interest on a topic which is very central in current European discussions and will constitute the basis of a second stage of future research
Free vibrations of elastic beams by modified nonlocal strain gradient theory
No full textSize-dependent axial and flexural free vibrations of Bernoulli-Euler nano-beams are investigated by the modified nonlocal strain gradient elasticity model presented in (Barretta & Marotti de Sciarra, 2018). The corresponding elastodynamic problem, with the natural constitutive boundary conditions, is solved by an effective analytical methodology. Axial and flexural fundamental frequencies are determined for cantilever and fully-clamped nano-beams. Effects of nonlocal and gradient scale parameters on fundamental frequencies are examined and compared with those obtained by Eringen's local/nonlocal mixture model. New benchmarks are found for vibrations of beams. The adopted nonlocal strain gradient model, with the appropriate constitutive boundary conditions, is capable of capturing both softening and stiffening dynamical responses. Accordingly, it provides an advantageous approach for design and optimization of a wide range of nano-scaled beam-like components of Nano-Electro-Mechanical-Systems (NEMS). (C) 2018 Elsevier Ltd. All rights reserved
Reply to Bernard Tombal's letter to the editor re: Alessandro Sciarra, Per Anders Abrahamsson, Maurizio Brausi, et al. Intermittent androgen-deprivation therapy in prostate cancer: a critical review focused on phase 3 trials. Eur Urol 2013;64:722-30
No full text[No abstract available
Elementi indicativi per la determinazione e l'applicazione di un valore di riferimento per l'1-idrossipirene urinario
No full textOn nonlocal coupling of damage and plasticity adopting integral theory
No full textThe effective stress concept was introduce by Kachanov to provide a phenomenological damage model for the isotropic case. Further in the early seventies a model of generalized standard elastoplastic material has been proposed by Halphen and Nguyen. In that model the flow rule is assigned by a normality rule to a generalized elastic domain defined in the product space of stresses and thermodynamic forces.
The necessity for introducing the nonlocal or gradient theory stems from the well-known fact that the classical rate-independent plasticity or damage theories do not possess an intrinsic length scale (Voyiadjis et al., 2004).
The aim of the paper is to formulate an nonlocal elastoplastic model coupled with strain damage in which the elastoplastic formulation as well as the stress decomposition of the nonlocal strain damage behaviour consistently follows from the thermodynamic analysis in a nonlocal integral context. The second objective of the paper is to derive a general thermodynamic framework which provides the tools to derive a consistent variational formulation for the nonlocal constitutive problem of elastoplasticity coupled with damage in the strain space. Accordingly the nonlocal counterpart of the Clausius–Duhem inequality is obtained and the maximum dissipation principle for the nonlocal coupled problem is obtained as a consequence of the model. From a computational point of view, an advantage of models with strain-based loading functions and explicit damage evolution laws is that the stress corresponding to a given strain can be evaluated directly without any need for solving a nonlinear system of equations (see e.g. Marotti de Sciarra, 2009)
Institutionalising Solidarity: A Genuine Challenge for Europe
No full textDialogue with Silvana Sciarra on Solidarity and Conflict. European Social Law in Crisis, Cambridge: Cambridge University Press, 2018status: Publishe
Comment on: "Prognostic value of preoperative albumin to globulin ratio in patients treated with salvage radical prostatectomy for radiation recurrent prostate cancer"
No full textFormulation of a phase field model of multiphase flow in deformable porous media
No full textIn this contribution a new model for partially saturated porous media is presented, within the framework of gradient poromechanics, based on a phase field approach. While the standard retention curve is expected still to provide the intrinsic retention properties of the porous skeleton, depending on the porous texture, an enhanced description of the surface tension between the wetting and the non-wetting fluid, occupying the pore space, is stated considering a regularized phase field model based on an additional contribution to the overall free energy depending on the saturation gradient. This approach provides similar results as those of the model based on the concept of specific interfacial area. The dependence of the free energy on the gradient of the saturation also implies that Darcy law must be extended to become a fourth order partial differential equation
On thermomechanics of multilayered beams
No full textIn this paper, the mechanical behavior of multilayered small-scale beams in nonisothermal environment is investigated. Scale phenomena are modeled by means of the mathematically well-posed and experimentally consistent stress-driven integral formulation of elasticity. The present research extends the treatment in Barretta, Čanađija, Luciano, and de Sciarra (2018b) confined to elastically homogeneous nano-scopic structures. It is shown that the non-locality leads to a complex coupling between axial and transverse elastic displacements. Such a size-dependent phenomenon makes the solution of the relevant nonlocal thermoelastostatic problem, governed by a system of two ordinary differential equations with ten standard boundary conditions and non-classical constitutive boundary conditions, significantly more involved with respect to treatments in literature. Thus, a novel solution methodology, based on Laplace transforms, is proposed and illustrated by examining simple structural schemes of current applicative interest in Nanomechanics and Nanotechnology
A constitutive model of coupled thermoelasticity with plasticity
No full textIt is well-known that the classical linear theory of heat conduction, based on Fourier's law for the thermal flux, predicts that a thermal effects at a point of a body is felt instantly at other points of the body. Therefore in past years several alternative theories of heat conduction have been proposed. In this paper we consider the non-classical theory of thermoelasticity developed by Green and Naghdi (1977) which incorporates the approach based on Fourier's law (referred to as type I), the theory without energy dissipation (type II) and a theory which allows finite wave propagation as well as energy dissipation (type III). Contributions on the Green and Naghdi (GN) approach can be found, among others, in Bargmann and Steinmann (2006) and references therein.
An analytical treatment of coupled thermoelastic problems is complex so that the development of alternative methods of analysis turns out to be important. Accordingly variational formulations of such problems can be of great interest from a theoretical point of view and from a computational
standpoint since they are the foundation to develop mixed finite elements.
In the present paper we treat the non-classical thermoelastic problem following the GN model of type II. The purpose of the contribution is to provide a constitutive model of thermoelasticity coupled with plasticity suitable to formulate variational formulations (see e.g. Marotti de Sciarra, 2009 for nonlocal problems) in order to consistently derive a finite element approach and the related algorithmic procedure.
The coupled thermoelastic model with plasticity is formulated in a geometrically linear range and is based on the internal variable theories of inelastic behaviours of associative type
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