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[en] The Gibbs condition is used to consider, how different phases can be obtained by surface effects. A new argument is given, why broken continuous symmetry gives rise to long range correlations. Finally it is argued that mixed KMS-states are unstable under changes on the surface. (Author)
[en] The purpose of this paper is to show which are the basic requirements for a valid modeling of thermal processes. Developing numerical models is not an end purpose. It is only a way of solving an engineering problem and thus, it is important to know what are the basic requirements which must be satisfied. The mathematical model will be valid only when the requirements of feasibility, consistency, stability, conservation, convergence and accuracy are fulfilled. We must be aware of these requirements also when we interpret the numerical solution in order to dissociate between the behavior of the process which has been modeled and the influence of the numerical schemes. These is extremely important to avoid solutions which are grid dependent or which have numerical instability. (author)
[en] We have investigated the effects of Re on the behaviors of H in W as well as their interaction with point defects using a first-principles method in combination with thermodynamic models. It is clearly found that the influence of Re on H is directly related to the distribution of Re in W. For the state of Re dispersed distribution, both a single Re and its complexes with point defects have very slight effect on H dissolution and retention in W. However, the influence of Re clusters (for the state of Re aggregation) on H is extraordinary stronger than that of a single Re. The retention of H in W can be significantly decreased by Re clusters, and their influences will be enhanced with the increasing of the number of Re atoms. This can be attributed to the electronic interaction between H and Re/W, in which the repulsion of Re–H is stronger than that of W–H. We have further examined the retention of H at different temperature in W based on the Polanyi–Wigner equation. It is found that a Re4-vacancy complex can only accommodate 4 H atoms at room temperature, ∼33% lower than the maximum number of H atoms in a mono-vacancy. These results give a reasonable interpretation for the experimentally observed D retention significantly decreasing in damaged W–Re alloy in comparison with that in damaged pure W. Consequently, our calculations provide a good reference for evaluating the influence of Re on the performance of W-PFM. (paper)
[en] The authors' elaboration of atmospheric radiative transfer processes in the theoretical framework of local irreversible thermodynamics is applied to study integral entropy production theorems for the global earth-atmosphere system. In detail it is shown that, with the inclusion of radiant absorption and emission being decisive effects for long-term climate variations, global evolution criteria can be formulated quite generally and applied to typical meteorological-climatological conditions. For our specific system in which radiant phenomena and Fourier-type heat conduction are combined, the validity of the Glansdorff-Prigogine general evolution condition is discussed. This principle is applied as a basis to derive a sufficient thermodynamical stability criterion for Budyko-Sellers type energy balance models. With given simplifications so-called kinetic or diffusive potentials characterizing Lyapounov-stability can be formulated. This analysis is used to discuss the limiting case of an isothermal gray (and especially a black) body whose entropy production becomes a minimum in stationary states. We notice too, how Paltridge's former hypothesis of a climate having a maximum production of entropy can be interpreted in this thermodynamical connexion
[en] We present a general theorem restricting properties of interfaces between thermodynamic states and apply it to the spin glass excitations observed numerically by Krzakala and Martin and separately by Palassini and Young in spatial dimensions d=3,4. We show that such excitations, with interface dimension ds< d, cannot yield regionally congruent thermodynamic states. More generally, zero density interfaces of translation-covariant excitations cannot be pinned (by the disorder) in any d but rather must deflect to infinity in the thermodynamic limit. Additional consequences concerning regional congruence in spin glasses and other systems are discussed
[en] Previously the five dimensional S1-rotating black rings have been superposed in a concentric way by some solitonic methods, and regular systems of two S1-rotating black rings were constructed by the authors and then Evslin and Krishnan (we called these solutions 'black di-rings'). In this place we show some characteristics of the solutions of five dimensional black di-rings, especially in thermodynamic equilibrium. After the summary of the di-ring expressions and their physical quantities, first we comment on the equivalence of the two different solution sets of the black di-rings. Then the existence of thermodynamic black di-rings is shown, in which both isothermality and isorotation between the inner black ring and the outer black ring are realized. We also give detailed analysis of peculiar properties of the thermodynamic black di-ring including discussion about a certain kind of thermodynamic stability (instability) of the system.
[en] The nonconventional thermodynamical approach to subatomic physics is described with large nonequilibrium effects taken into account by introducing the temperature continuum O≤T<∞. The approach is an expansion of the classical fluctuation theory and chemical-reaction formalism. A large body of problems in low- and high-energy nuclear physics is solved in the framework of super-nonequilibrium thermodynamics. 30 refs., 2 figs., 1 tab
[en] A sulfur-iodine (S-I) thermochemical cycle is being investigated nationally and/or internationally for a centralized hydrogen production by means of a nuclear heat source. However, the S-I cycle involves a complex and highly nonideal behavior both in phase equilibria and in reactions. In the field of applied thermodynamics, the development of a model suitable for the S-I cycle process is one of the challenging issues. However, recently, remarkable progress has been made to evaluate and improve the S-I cycle. In this work, thermodynamic models dealing with electrolytes, which should be the main considerations for the S-I cycle, are reviewed and, then, the recent models are addressed with their basic concepts
[en] Heat pumping is a highly energy-efficient technology that could help reduce energy and environmental problems. The efficiency of a heat pump greatly depends on the individual and integral performance of the components inside. In this study, heat pump performance is investigated with a special focus on heat exchangers. Experimental data obtained from comprehensive heat pump measurements performed at the Austrian Institute of Technology (AIT) were analyzed with the help of thermodynamic models developed for this purpose. The analysis shows that the performance of heat exchangers varies widely resulting in substantial COP differences among the heat pumps. The models and methodology developed in this study are found capable of extracting useful information from measurement data quickly and accurately and could be useful for the industry. - Research highlights: → A heat pump database has been analyzed focussing on the influences of heat exchangers on COP. → It was shown that an empirical equation could excellently correlate experimental COP data with relevant parameters. → It was found that heat exchanger design alone caused 15-20% difference in COP.