Results 1 - 10 of 102
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[en] In this paper, green emitting Mn-doped Zn2SiO4 rodlike nanoparticles were synthesized by a hydrothermal method using ZnCl2 and Na2SiO3 at 280 deg. C. The effects of treatment temperature and time on the crystallite structure, size and morphology were investigated. The Zn2SiO4:Mn rodlike nanoparticles with a diameter of 20-30 nm and a mean length of 300 nm were prepared by using the co-doped Ce ions. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence spectroscopy. This procedure provides an easy way for the synthesis of well-crystallized Zn2SiO4:Mn with uniform morphology at low temperature
[en] By studying the EVALUATOR, economic evaluation expert system of uranium mine project, the theoretical fundamentals of expert system, principle of inference mechanism, implementation of knowledge base, realization of explanation mechanism, acquisition of domain knowledge and representation of knowledge were described, especially the subjective Bayes approach for inexact reasoning problem used in EVALUATOR was discussed in detail
[en] The quantity and influence factors of monitor well at in-situ leaching of uranium are described, the sampling way, sample preservation, option of indicator parameters and the analysis of monitor results are discussed as well
[en] The thermodynamic extremal principle was applied to model of diffusion-controlled phase-transformations in multi-component substitutional alloys, in which dissipations by interface migration and trans-interface diffusion were integrated for a sharp interface. In the modeling, a new concept of trans-interface diffusion in two-steps, i.e. from the product phase to the interface and from the interface to the parent phase, was introduced, ascribing to which the model follows the Onsager's reciprocal relation. In contrast to the work of Svoboda et al. (2004) that considers only the interfacial dissipation by interface migration, non-equal jumps of chemical potentials across the interface are herein allowed. Applications to the Fe−Cr−Ni and Fe−Ni alloys showed that the model is able to describe accurately not only the kinetic processes of massive transformation and diffusive transformation but also the critical limit between them. Since the transformation direction is not a priori condition for model calculations, the model is of potential value in applications to the cases in which the migrating direction changes, e.g. cycle phase-transformations etc.
[en] Modeling of non-equilibrium solidification in multi-component alloys is of singular importance in microstructure control, which however owing to the complex systems with complex additional constraints is still an open problem. In this work, the thermodynamic extremal principle was applied to solve the complex additional constraints self-consistently in thermodynamics. Consequently, short-range solute redistribution and long-range solute diffusion that share the same mobility are integrated naturally into the solute diffusion equations, thus avoiding the introduction of additional kinetic coefficients (e.g. interface permeability) to describe solute redistribution. Application to the non-equilibrium solidification of Al-Si-Cu alloys shows that anomalous solute trapping and anomalous solute profiles within the diffuse interface could occur, thus highlighting the important effect of the interaction among the component elements on the interface kinetics. The current phase-field model might be preferred for simulations not only because of its simplest form of evolution equations but also its feasibility to increase the simulation efficiency by the “thin interface limit” analysis.
[en] Data processing and error analysing for yellow cake products were discussed. The results show that it is dependable by data processing of 345 barrels of products with computer. Analysis of errors (net wet mass, uranium content percent, moisture and uranium mass) is given, which is useful to mines and Hengyang Uranium Mill
[en] Combined with a case of in-situ leaching project, the author discusses the principle and approaches for push-pull equilibrium controlling, and gives the suggestions solving the un-equilibrium problems of push-pull in well field during operation
[en] Coupling with the thermodynamic database and incorporating the effects of local non-equilibrium and off-diagonal diffusional interactions, an extended morphological stability analysis was performed for a planar interface upon rapid solidification of concentrated multi-component alloys. Compared with the previous work, the model is able to clarify the effects of concentration dependence and diffusional interactions on the interface stability. Taking the Al–Mg–Zn alloy as an example, the neutral stability, i.e. the critical Zn concentration (with Mg concentration fixed) for the breakdown of the planar interface, was studied. The stability mechanisms for the neutral Zn concentration subjected to different Mg concentrations and the off-diagonal diffusion effect were clarified. In particular, for high Mg concentrations, a stage of absolute instability dependent on the Mg diffusion effect but independent of the Zn concentration happens. Although the off-diagonal diffusion is several orders of magnitude smaller than the solute diffusion coefficients, it can significantly change the Zn concentration for the neutral stability conditions