Our experience of executing proficiency testing programs on the analysis of precious metals and precious metal bearing materials is summarized. Six proficiency testing programs of the ”distributed ...sample testing” type were carried out using samples essentially distinct from each other: (I) certified samples of fine gold and fine silver, and (II) recoverable raw (scrap and catalyst waste) containing precious metals of unknown contents. The test results were assessed using the London Bullion Market Association (LBMA) rules and by Z-criteria using the ISO/IEC Guide 43 scale. Satisfactory results were presented by all participants for the analysis of certified samples of fine gold and fine silver. The results of catalyst waste analysis agreed rather well, whereas the scrap analysis revealed an essential discrepancy in the data for some samples. The reasons for such discrepancies are discussed.
A simple, fast and precise method for the electrothermal atomic absorption spectrometry (ETAAS) determination of Au(III), Ag(I), Pd(II) and Pt(IV) from a single aliquot at the level of 10
−4% in ...complex samples was developed. The method is based on reducing the interfering effect of Al, Fe, Cu and Ni macrocomponents on determination of Au(III), Ag(I), Pd(II) and Pt(IV) by ETAAS by adjusting the acidic sample solution to pH 9–11 using aqueous ammonia. As a result, 98.4% of Al and 99.7% of Fe precipitated smoothly at room temperature and without additional reagents needed. Furthermore, Au(III), Ag(I), Pd(II) and Pt(IV) did not co-precipitate and remained in the soluble form as ammonia complexes. While soluble ammonia Ni and Cu complexes were also produced, they decomposed in a graphite furnace at 400
°C and did not interfere with ETAAS determination of noble metals. In addition, the benefit of the ETAAS determination of Au(III), Ag(I) in the ammonia complexes is that there were no losses of Ag and Au due to the formation of insoluble AgCl and vaporization of gold and silver chlorides before atomization or incomplete dissociation in the gas phase when conventional sample treatment methods were used The relative standard deviations (R.S.D.) were in the range of 8–10% for determination of Au and Pd in aluminium catalysts, Ag in pure gold samples, and Pt in nickel tailings.
The paper presents a simulation-based approach to creation of decision support system for IT Service Management. The presented approach includes monitoring of stochastic data IT Services and ...calculation of measure of alignment to business goals with its characteristic basing on SLA/SLO. The approach combines the benefits of two kinds of models: analytical and simulation ones. The key idea of the paper is to demonstrate how modern methods of stochastic process analysis may enhance trustworthiness and quality of decision making along business goals within IT Services.
Language materials clarify the premises in social practice to define the phenomenon called violence. As a starting point, I will use Russian lexemes. The word nasilie (violence) clearly stems from ...the word sila (force), mostly endowed with a positive meaning and energy. At the same time, the world sila is ambiguous, multifaceted. It has such synonyms as moshch' (might, power), moshchnost' (mightiness, power), mogushchestvo (enablement), and is also indirectly related to the word voisko (cohort, army), and more.
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The paper presents a formalized interpretation of a hierarchical technology for expansion planning of large electric power system (EPS) and demonstrates the main features and characteristics of ...AnyLogic simulation software to study the problem of hierarchical modeling of EPS expansion.
The finite element method (FEM) computer simulation of the three-high radial shear rolling of Ti-6Al-4V alloy round billets was conducted using QForm software. The simulation was performed for the ...MISIS-100T rolling mill's three passes according to the following rolling route: 76 mm (the initial billet diameter) →65 mm→55 mm→48 mm (the final billet diameter). The change in the total velocity values for the points on the radius of the 48 mm diameter billet was estimated while passing the rolls' draft. The relative increase in the accumulated strain was estimated for the same points. Then, experimental shear rolling was performed. Grain sizes of the α- and β-phases were estimated in the cross section of the final billet at the stationary stage of rolling. The grain size distribution histograms for different phases were plotted. An area was found in the billet's cross section in which the trend of change in the total velocity of the points changed. This area represented a neutral layer between the slowing peripheral segments of the billet and the accelerating central segments of the billet. Inside this neutral layer, the limits of the cylindrical surface radius value were estimated. Experimental radial shear rolling was performed to compare the experimental rolling results (the billet microstructure investigation) with the computer simulation results. The computer simulation obtained two estimations of the radius limits: 8-16 mm (based on the analysis of the total velocity change) and 12-16 mm (based on the accumulated strain's relative increment change). The experimental rolling obtained two more estimations of the radius limits: 8.4-19.5 mm and 11.3-19.7 mm-based on the results of the microstructure investigation. It was confirmed that varying the kinematic and deformation parameters of radial shear rolling allows regulation of the thickness of the peripheral fine-grain layer and the diameter of the central coarse-grain layer of the rolled billets.
