SUMMARYPart 1 of the paper presents a new numerical model of hygro-thermal and hydration phenomena in concrete at early ages and beyond. This is a solidification-type model where all changes of material properties are expressed as functions of hydration degree, and neither as maturity nor as equivalent hydration period as in maturity-type models. A mechanistic approach has been used to obtain the governing equations, by means of an averaging theory of Hassanizadeh and Gray, also called hybrid mixture theory. The developments start at the micro-scale and balance equations for phases and interfaces are introduced at this level and then averaged for obtaining macroscopic balance equations. Constitutive laws are directly introduced at macroscopic level. The final equations, mass (water species and dry air), energy and momentum balance equations, have been written in terms of the chosen primary variables: gas pressure, capillary pressure, temperature and displacements. An evolution equation for the internal variable, hydration degree, describes hydration rate as a function of chemical affinity, considering in addition to the existing models, an effect of the relative humidity on the process. The model takes into account full coupling between hygral, thermal and chemical phenomena, as well as changes of concrete properties caused by hydration process, i.e. porosity, density, permeability, and strength properties. Phase changes and chemical phenomena, as well as the related heat and mass sources are considered. Two examples showing possibilities of the model for analysis of autogenous self-heating and self-desiccation phenomena, as well as influence of the

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SUMMARYIn Part I of this paper (Int. J. Numer. Meth. Eng., in print) a mechanistic model of hygro-thermochemical performance of concrete at early ages has been introduced. Additionally, as compared to the existing models (e.g. J. Eng. Mech. (ASCE) 1995; 121(7):785-794; 1999; 125(9):1018-1027), an effect of relative humidity on cement hydration rate and associated hygro-thermal phenomena have been taken into account. Here we deal with mechanical performance of concrete at early ages and beyond, and in particular, evolution of its strength properties (aging) and deformations (shrinkage and creep strains), described by using the effective stress concept. This allow us for explanation and modelling of phenomena known from experiments, like drying creep (e.g.

In this paper, a model for the analysis of the behaviour of concrete at temperature largely exceeding critical \ud point of water, is presented. In this temperature range liquid phase, i.e. capillary phase, and gas phase \ud cannot be distinguished and only the latter exists. Consequently, capillary pressure has no more physical \ud meaning above this point and liquid water is present only as physically adsorbed water. In this work, we \ud give a different physical interpretation to the capillary pressure and use it still for the description of the \ud hygrometric state of concrete in the zone, where temperature exceeds the critical point of water. \ud Considerable thermal dilatation of the liquid water and the real behaviour of water vapour close to critical \ud temperature are taken into account. Moreover, a special switching procedure in order to avoid the Stefan- \ud like problem, which subsequently arises, is described and employed in the calculations. Finally, several \ud numerical examples demonstrating the robustness of the adopted solution have been shown

Blue light emitting diode internal and injection efficiency AIP Advances 2, 032117 (2012) Enhancement of hole injection and electroluminescence characteristics by a rubbing-induced lying orientation of alpha-sexithiophene J. Appl. Phys. 112, 024503 (2012) Study of field driven electroluminescence in colloidal quantum dot solids J. Appl. Phys. 111, 113701 (2012) Indium incorporation and emission properties of nonpolar and semipolar InGaN quantum wellsElectroluminescence from metal-insulator-semiconductor structures with silicon dioxide (SiO z ) layers containing varying amounts of excess silicon (Si) in the form of tiny Si precipitates have been studied in detail. Bulk insulator emission from the Si islands is shown to dominate over emission from either the Si0 2 matrix material or the metallic gate material by studies of oxide or metal gate material, voltage polarity, and insulator thickness dependencies. Several distinct spectral peaks are observed in the energy range from 1.5 to 5 eV which cannot be attributed to optical interference effects. The higher-energy peaks show a strong dependence on electric field relative to that at the lowest energy (1.7-2 eV). The entire spectral amplitude shows a strong dependence on high-tempera.ture annealing and excess Si content, decreasing drastically with increasing Si or decreasing annealing temperature. These results are shown to be consistent with light emission during electronic transitions between discrete energy levels associated with Si islands and/or their interface with the Si0 2 host matrix material. Quantum size effects, similar to those observed in semiconductor superlattices, are proposed as one possible explanation.