Volume 24, Issue 4

Within the framework of Extended Irreversible Thermodynamics (EIT) a phenomenological theory is proposed for a polarizable and magnetizable plasma in an electromagnetic field. In particular, for the polarization a transport equation is proposed generalizing the well-established Debye's law for dielectric relaxation. For the magnetization a transport equation is proposed generalizing the well-established Langevin's law for magnetic relaxation. The present equations correspond to those obtained by Dixon involving also coupling terms with the heat flux. Finally, in the special case in which cross-effects are not taken into account, the dispersion relation for plane weak electromagnetic disturbances is derived.

Non-equilibrium thermodynamic model equations describing transport properties of non-ionic and heterogeneous n-component solutions have been studied in a double-membrane system. The system is composed of two complexes: boundary layer/membrane/boundary layer. Definitions of hydraulic permeability ( L̄ p ), reflection ( σ̄ * ) and diffusive permeability (Ω̄) coefficients of the double-membrane system and relations between the coefficients of the double-membrane system ( L̄ p , σ̄ * , Ω̄) and the respective quantities of the single membranes of the system ( L p , σ*, Ω) are given. The validity of the model has been checked in the case of binary and ternary solutions, using a membrane cell with horizontally mounted membranes. The diffusive permeability and reflection coefficients were determined as functions of solution concentration and gravitational configuration.

The historical background, research development, and the state-of-the-art of finite time thermodynamic theory and applications are reviewed from the point of view of both physics and engineering. The emphasis is on the performance optimization of thermodynamic processes and devices with finite-time and/or finite-size constraints, including heat engines, refrigerators, heat pumps, chemical reactions and some other processes, with respect to the following aspects: the study of Newton's law systems, an analysis of the effect of heat resistance and other irreversible loss models on the performance, an analysis of the effect of heat reservoir models on the performance, as well as the application for real thermodynamic processes and devices. It is pointed out that the generalized thermodynamic optimization theory is the development direction of finite thermodynamics in the future.

Novel kinetic phase diagrams for homogeneous nucleation during non-equilibrium solidification of Ag-Cu alloys were evolved by stochastic modelling. The allowable undercoolings and the composition of the primary nucleating phase at any cooling rate and liquid composition could be read from these diagrams. The calculated values were found to lie within the thermodynamically permissible limits determined through construction of non-isothermal metastability field diagrams.

We analyze in a simple system the relation between local and global thermodynamic stability. This example shows how the global stability can be understood in terms of the structures existent in the local dynamics.

A brief analysis of the classical derivation of the continuity equation in general relativity is presented. The consequences of the equation obtained are reviewed and compared with similar results related with the conservation of particles (baryons and leptons). Emphasis is made on the fact that different transport equations may be derived from the possible choices of the mass balance equation in non-equilibrium formalisms. Nevertheless, the continuity equation is not at odds with the notion of particle conservation.