A minimum principle for the quasi-static problem in linear viscoelasticity

A minimum principle is set up for the quasi-static boundary-value problem (QSP) in linear viscoelasticity. A linear homogeneous and isotropic viscoelastic solid under unidimensional displacements is considered along with the complete set of thermodynamic restrictions on the relaxation function. It is assumed that boundary conditions are of Dirichlet type and initial history data are not given. The variational formulation of QSP is set up through a convex functional based on a "weighted" $L^2$ inner product as the bilinear form and is strictly related to the thermodynamic restrictions on the relaxation function. As an aside, the same technique is proved to be applicable to analogous physical problems such as the quasi-static heat flux equation

New variational principles in quasi-static viscoelasticity

A "saddle point" (or maximum-minimum) principle is set up for the quasi-static boundary-value problem in linear viscoelasticity. The appropriate class of convolution-type functionals for it is taken in terms of bilinear forms with a weight function involving Fourier transform. The "minimax" property is shown to hold as a direct consequence of the thermodynamic restrictions on the relaxation function. This approach can be extended to further linear evolution problems where initial data are not prescribed

Uniform attractors for a non-autonomous semilinear heat equation with memory

n this paper we investigate the asymptotic behavior, as time tends to infinity, of the solutions of a non-autonomous integro-partial differential equation describing the heat how in a rigid heat conductor with memory. Existence and uniqueness of solutions is provided. Moreover, under proper assumptions on the heat flux memory kernel and on the magnitude of nonlinearity, the existence of uniform absorbing sets and of a global uniform attractor is achieved. In the case of quasiperiodic dependence of time of the external heat supply the above attractor is shown to have finite Hausdorff dimension

A quantitative model for volcanic hazard assessment

Volcanic hazard assessment is a basic ingredient for risk-based decision-making in land-use planning and emergency management. Volcanic hazard is defined as the probability of any particular area being affected by a destructive volcanic event within a given period of time (Fournier d’Albe 1979). The probabilistic nature of such an important issue derives from the fact that volcanic activity is a complex process, characterized by several and usually unknown degrees of freedom that are often linked by nonlinear relationships (e.g. Bak et al. 1988). Except in sporadic cases, the result of this complexity is an intrinsic, and perhaps unavoidable, unpredictability of the time evolution of the volcanic system from a deterministic point of view

Probabilistic Volcanic Hazard and Risk Assessment

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Lipid Process Markers of Durum Wheat Debranning Fractions

At present, whole grains are usually obtained by adding bran and middlings to refined flours, and this recombination leads to certain variations in the ratio of endosperm, bran and germ, resulting in flours with very different compositional characteristics and rheological properties. Therefore, this study focuses on the identification of specific lipid markers in different debranning fractions of Italian and Canadian durum wheat blends. The by-products obtained from five different debranning levels (3, 6, 9, 12 and 15%) had a high content of monounsaturated fatty acids and a higher concentration of tocopherols and sterols than the corresponding debranned grains. The Italian and Canadian durum wheat samples did not show significant differences in the content of these bioactive lipid compounds. In particular, palmitic acid, oleic acid, tocopherol isomers and total sterols could be useful biomarkers for evaluating the grain-to-tissue ratio in recombined flours

Improving working conditions and job satisfaction in healthcare. A study concept design on a participatory organizational level intervention in psychosocial risks management

This paper contributes to the literature on organizational interventions on occupational health by presenting a concept study design to test the efficacy of a Participatory Organizational level Intervention to improve working conditions and job satisfaction in Healthcare. The Participatory Organizational-level Intervention is developed using the Italian methodology to assess and manage psychosocial risks tailored to Healthcare. We added an additional step; evaluation, aiming to examine how the intervention works, what worked for whom in which circumstances. This ongoing study is conducted in collaboration with two large Italian Hospitals (more than 7,000 employees). The study design comprises a quasi-experimental approach consisting of five phases and surveys distributed pre- and post-intervention aiming to capture improvements in working conditions and job satisfaction. Moreover, to evaluate the efficacy of the Intervention in terms of process and content, we use a realist evaluation to test Context-Mechanisms-Outcome (CMO) configurations. We collect contextual factors at baseline and during and post-intervention process data on the key principles of line manager support and employees participation. This study is expected to provide insights on methods and strategies to improve working conditions and employees’ job satisfaction and on national policies in the occupational health framework