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We consider a system of balance laws arising in extended irreversible thermodynamics of rigid heat conductors, together with its differential consequences, namely the higher-order system obtained by taking into account the time and space derivatives of the original system. We point out some mathematical properties of the differential consequences, with particular attention to the problem of the propagation of thermal perturbations with finite speed. We prove that, under an opportune choice of the initial conditions, a solution of the Cauchy problem for the system of differential consequences is also a solution of the Cauchy problem for the original system. We investigate the thermodynamic compatibility of the system at hand by applying a generalized Coleman- Noll procedure. On the example of a generalized Guyer-Krumhansl heat-transport model, we show that it is possible to get a hyperbolic system of evolution equations even when the state space is non-local. [ABSTRACT FROM AUTHOR]

In this paper we determine the physical conditions ensuring that the efficiency of a thermoelectric nanowire with two temperatures is optimal. We consider the case in which the entropy for unitary volume depends on the equilibrium variables only, and the case in which such a quantity depends on the dissipative fluxes, too. We prove that in these two different situations the conditions of optimal efficiency are different. [ABSTRACT FROM AUTHOR]

We propose a nonlinear model for thermoelectric coupling which is based on the thermomass theory for heat conduction. We show that in this model, the second Kelvin relation and the classical Onsager relations are no longer satisfied simultaneously, namely, if one holds, then the other one breaks down, and viceversa. As a function of the different breaking, we evaluate the efficiency of a thermoelectric generator. The influence of the electric-charge gradient on the efficiency of thermoelectric coupling is investigated as well. [ABSTRACT FROM AUTHOR]

A geometrical description of micropolar mixtures theory for N components including matter diffusion is analyzed from a thermodynamical viewpoint with internal variables. This theory introduces one independent rotation for each material element so that the resulting stress and strain tensors are generally non-symmetric. In order to consider dissipative effects due to rotation and to thermodiffusion we introduce a set of N independent scalar internal variables, which we denote by γA; the set of N independent vectorial internal variables defined by their gradients is indicated as ΛA. The behavior of the mixture is therefore described by a state space W including the classical variables (i.e. mass density, mass concentration, temperature and so on) together with internal variables and with their first gradients satisfying an evolution equation. General thermodynamical restrictions and residual dissipation inequalities are obtained by Clausius-Duhem inequality. Finally, by using geometric technique due to Maugin, the heat equation is derived in the first and second form. [ABSTRACT FROM AUTHOR]

In a previous paper we have sketched a geometrical model for ferromagnetic crystals within a geometrized framework of simple materials with internal variables. Using a model of magnetizable media investigated by Maugin and coworkers, in the state vector the magnetization vector together with its space gradient (subjected to an evolution equation depending on both internal and external magnetic field) were included. In this paper we deepen the study of this geometrical model. In particular, from the exploitation of Clausius-Duhem inequality the entropy production and the state laws are calculated explicitly and starting from one appropriate dynamical system the expression for the entropy function and necessary conditions for its existence are got. Finally, using a Maugin's technique, the heat equation in the first and second form is derived. [ABSTRACT FROM AUTHOR]

In this paper a model for dielectric material in the formalism of Kluitenberg's theory on dielectric relaxation phenomena is proposed. The aim of the paper is to suggest a thermodynamic model with internal variable for dielectric isotropic material; in particular, by introducing the reciprocal complex dielectric susceptibility, expressions will be proposed for the dielectric storage modulus and dielectric loss modulus in cases of low and high frequencies. Finally, an expression for the reciprocal of complex susceptibility allows us to compare the results obtained with experimental data in the case of low frequencies. [ABSTRACT FROM AUTHOR]

A description of mixtures, including matter diffusion and suspensions, is analyzed from a thermodynamic viewpoint with internal variables. In order to consider dissipative effects due to thermo-diffusion we introduce a set of N independent scalar internal variables, which we denote by γA. The behavior of the mixture is therefore described by a state space W including the classical variables mass density, mass concentration, temperature, and internal variables together with their first and second gradients satisfying evolution equations. General thermodynamic restrictions and residual dissipation inequalities are obtained by the Clausius–Duhem inequality. [ABSTRACT FROM AUTHOR]

A model of binary mixtures with an application to superfluid helium is analyzed from a thermodynamical viewpoint with internal variables. Constitutive equations under hypotheses of linearity are obtained. [ABSTRACT FROM AUTHOR]

A model of a mixture with N different components is analyzed from a thermodynamic viewpoint with internal variables, both in the presence and absence of viscosity. Thermodiffusion phenomena are described by N internal variables ( N ≥ 2). General thermodynamic restrictions and residual dissipation inequalities are obtained by the Clausius–Duhem inequality. [ABSTRACT FROM AUTHOR]

A model of polarizable media investigated by Maugin and coworkers is considered as the domain of application of a recent method for the geometrization of the thermo-elasticity of continua with internal variables. The polarization together with its space gradient are assumed as state variables expressed in terms of internal variables evolving according to a relaxation law driven by external and internal electric fields. The entropy productions in Clausius-Duhem inequalities are calculated explicitly. [ABSTRACT FROM AUTHOR]

The mathematical properties of thermodynamics with internal variables are investigated in a general framework, both for the local and gradient theory. The consequences of the Second Law of Thermodynamics on the constitutive equations, together with some peculiar properties of the equilibrium states, are proved. The evolution equations of the internal variables are derived as a system of Hamilton equations resulting from a suitable Legendre's transformation. [ABSTRACT FROM AUTHOR]

In this paper the problem of magnetically undeformable polarizable media in the presence of an electromagnetic field is analyzed from a thermodynamic viewpoint. The thermodynamic transformations are explicited as functions in the state space in which one of the variables, characterizing the magnetic polarization, is given as an internal variable. The entropy form along the thermodynamic transformation is calculated for para- and diamagnetic media and the necessary conditions for its existence are given. [ABSTRACT FROM AUTHOR]

We analyze the efficiency in terms of a thermoelectric system of a one-dimensional Silicon–Germanium alloy. The dependency of thermal conductivity on the stoichiometry is pointed out, and the best fit of the experimental data is determined by a nonlinear regression method (NLRM). The thermoelectric efficiency of that system as function of the composition and of the effective temperature gradient is calculated as well. For three different temperatures ( T = 300   K , T = 400   K , T = 500   K ), we determine the values of composition and thermal conductivity corresponding to the optimal thermoelectric energy conversion. The relationship of our approach with Finite-Time Thermodynamics is pointed out. [ABSTRACT FROM AUTHOR]

Abstract: In this paper dielectric phenomena with two relaxation times are discussed. By assuming a sinusoidal form for induction vector a sinusoidal electric field is generated and it depends on unknown phenomenological coefficients whose expressions together to their numerical values as functions of frequency are obtained. Moreover, electromagnetic wave propagation is analysed obtaining wave vector as function of the aforementioned coefficients. The results are applied to a Vinylidene Chloride-Vinyl Chloride (VDC–VC) to test the applicability of the model. [Copyright &y& Elsevier]

Highlights: [•] Development of inhibitors acting against those viral enzymes operating via a cooperative two-metal ion mechanism, such as HIV integrase (IN), requires optimizing the binding affinity to the target. [•] We have defined an experimental procedure for obtaining reliable thermodynamic data by ITC in methanol/water=9/1 (v/v) as solvent. [•] Formation heats in mixed solvent of the complexes formed by a ligand, model of Raltegravir, with Mg(II), Mn(II), Co(II) and Zn(II) are here reported. [ABSTRACT FROM AUTHOR]