1,721,004 research outputs found
Sull'incertezza di misura associata al monitoraggio di un fenomeno acustico
No full textIS News Ordine degli Ingegneri della Provincia di Salern
Some continuous dependence results about high-order time differential thermoelastic models
No full textThis article aims to contribute to the investigation of the well-posedness question for three different heat conduction thermoelastic models, obtained starting from the dual-phase-lag (DPL) constitutive equation in its most general time differential formulation and considering Taylor expansion orders higher than those most commonly studied in literature so far. It is necessary to emphasize right from now that the investigation of such thermomechanical models, although they originate in terms of constitutive equations from
suitable Taylor series expansions, has to be properly interpreted not as an attempt to emulate the delayed behavior characteristic of the original (i.e. not expanded) DPL model, but rather with the awareness of deepening the well-posedness question for three different stand-alone and self-consistent models. In particular, three estimates are obtained (one for each of the considered models) able to show the continuous dependence of the solutions of the related initial boundary value problems with respect to the supply
terms and to the initial given data. All the continuous dependence results are obtained without the need to impose particular restrictions involving the delay times, except for the requirement that they are strictly positive
Uniqueness theorems about high-order time differential thermoelastic models
No full textThe purpose of the present manuscript is to investigate the well-posedness question for three different stand-alone and self-consistent thermoelastic models derived from the time differential formulation of the dual-phase-lag heat conduction law and characterized by Taylor expansion orders higher than those most commonly considered in literature up to now. The main motivation at the basis of this study is that the interaction among multiple energy carriers progressively gains significance as the observation scales reduce and has, as a direct consequence, the involvement of high-order terms in the time differential dual-phase-lag heat conduction constitutive equation. Considering inhomogeneous and anisotropic linear thermoelastic materials, we are able to prove three uniqueness results through the use of appropriate integral operators and Lagrange identities; the results are proved without any restriction imposed on the delay times other than their positivity
Spatial estimates for transient and steady-state solutions in transversely isotropic plates of Mindlin-type
No full textThis paper concerns with a state of bending for a linear transversely isotropic plate model based on the Mindlin assumption on the displacement. By using appropriate families of line-integral measures, we are able to establish results about the spatial behaviour of transient and steady-state solutions. All the results are obtained under relaxed hypotheses on the positive definiteness of the elasticity tensor
On the exponential decay for viscoelastic mixtures
No full textThis paper concerns the study of mixtures composed of a thermoelastic solid and a viscous fluid. For these mixtures, the dissipation effects are connected with the viscosity rate of one constituent and with the relative velocity vector. Using the time-weighted surface power method, associated with the linear process, we obtain some spatial decay estimates, characterized by time-independent and time-dependent decay rates, respectively. The first type of estimate is appropriate for large values of time, while the other is useful for short values of the same variable
A domain of influence result about the time differential three-phase-lag thermoelastic model
No full textThis work represents a natural outlet of recent investigation about the well-posed question for the time differential three-phase-lag model of thermoelasticity. We deal with a cylindrical domain filled by an anisotropic and inhomogeneous thermoelastic material and assume that the initial-boundary data as well as the external supply terms that characterize the problem in
concern are concentrated in a compact region of the considered volume. Within such a framework, we show the spatial behavior of the solutions in terms of existence of a domain of influence of the assigned data. We will remark that our results are obtained under restrictions involving the constitutive tensors and the delay times that are in complete agreement with the hypotheses that make the time differential three-phase-lag model thermodynamically consistent. The case of a semi-infinite cylindrical domain
is also considered
Some results on the spatial behaviour for elastic mixtures
No full textThis article studies the spatial behaviour of solutions for some classes of homogeneous and isotropic simple elastic mixtures,
for which the internal energy density is not always a positive definite quadratic form. By introducing some appropriate measures, we obtain the domain of influence theorem and the spatial decay estimates with time-independent decay rate inside the domain of influence
On the Deformation of the Surface of an Elastic Medium with a Cavity
No full textThe problem concerning the investigation about the anti-plane deformation of an half-plane surface, in presence of a cavity and a shear force on the external surface, is formulated and solved in some details. The analytical results obtained are used to solve numerically the problem for different configurations of the system. Finally, some graphics showing such solutions are reported
On the influence of voids on the depth of an external signal in thermoelasticity with two relaxation times
No full textThis work aims to highlight, by a series of simulations, the effect of the presence of pores in the material matrix on the transmission depth of a thermomechanical signal: two linear thermoelastic models are considered, for which the thermal response obeys a time-differential constitutive equation with two relaxation times, derived from the dual-phase lag theory. A porous material matrix, modeled on the basis of the Cowin-Nunziato theory, is compared with its counterpart without voids: this is done under hypotheses of linearity, compatible with the assumption to deal with very small spatial scales, in the order of the micrometer or nanometer. The results of such simulations are graphically presented and are completely unexpected; in the opinion of the authors, they can represent an interesting starting point for further discussions and insights
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