BaO−B2O3 system and its mysterious member Ba3B2O6

The first systematic study of the BaO–B₂O₃ system and barium orthoborate Ba₃B₂O₆ (3BaO·B₂O₃) was reported in 1949. Thereafter, the system was repeatedly refined but the structure of Ba₃B₂O₆ compound has not been adequately studied yet. In our study we have, for the first time, obtained the crystalline samples of Ba₃B₂O₆. The solved structure (Pbam, a = 13.5923(4) Å, b = 13.6702(4) Å, c = 14.8894(3) Å) belongs to the class of ‘anti‐zeolite’ borates with a pseudotetragonal [Ba₁₂(BO₃)₆]⁶⁺ cation pattern which contains channels along the c axis filled with anionic clusters. The Ba₃B₂O₆ compound may be regarded as a fluorine‐free end‐member of the Ba₃(BO₃)_2–xF_3x solid solution. The BaO–B₂O₃ phase diagram presented in our study is based on our research and literature data.     

Illustrative Molecular Visualization with Continuous Abstraction

Molecular systems may be visualized with various degrees of structural abstraction, support of spatial perception, and ‘illustrativeness.’ In this work we propose and realize methods to create seamless transformations that allow us to affect and change each of these three parameters individually. The resulting transitions give viewers a dedicated control of abstraction in illustrative molecular visualization and, consequently, allow them to seamlessly explore the resulting abstraction space for obtaining a fundamental understanding of molecular systems. We show example visualizations created with our approach and report informal feedback on our technique from domain experts.     

Probabilistic modeling of the corrosion of steel structures in marine water-development works

Considering that corrosion takes place as a random process over time, a a probabilistic approach was utilized in this paper. The corrosion of metallic sheet piling employed in the fascia wall of a bulwerk is considered as an example. A stochastic model is constructed on the base of a modified Weibull distribution function with consideration of parameters of the corrosion process as a function of time. One of the factors defining the corrosion rate of the sheet piling is the degree of access of a section of the wall to the zone of variable water level, or the underwater zone. The type of corrosion—continuous or local—is another factor. The accuracy of corrosion prediction in the underwater zone is higher than that in the zone of variable water level.     

Simulation of the high-octane alkylates manufacturing considering the process unsteadiness

The aim of this paper work is to study the model of the process of sulphuric-acid alkylation of isobutane using a mathematical model. The model of the object was developed considering the physicochemical regularities of the process. The paper analyzes the main processes occurring at the installation and performs the results of model verification. In addition, the technological scheme of one of the sulphuric-acid alkylation existing installations were considered. The developed program is able to calculate the composition of the obtained alkylate, to determine the yield of target products and by-products, to select optimal technological process conditions for a given raw material composition. It was noted, that the consumption of sulfuric acid increases as a result of the accumulation of high-molecular organic compounds in it, as well as its dilution with water, which enters the reactor along with the raw material and forms during the side reactions of the process.     

A Study of Sialon Synthesis from Kaolin by Carbothermal Reduction and Simultaneous Nitriding

X-ray diffraction, derivatographic analysis, and the BET method are used to study the processes of synthesis of sialons by carbothermal reduction and simultaneous nitriding of kaolin of the Kyshtymskoe deposit. The synthesis is performed by roasting a mixture of kaolin with colloidal graphite S-1 poured freely or pressed into specimens in a discontinuous-flow furnace with a graphite heater. The influence of the synthesis conditions on the phase composition, the specific surface of the powders, the gas permeability, and the pore size in sialon specimens is established. It is shown that when pressings fabricated from kaolin mixed with graphite S-1 are roasted in nitrogen, the resulting material can have a porosity of 60% with pores < 1 μm in size and a gas permeability of 0.02 – 0.08 μm², which can become a basis for developing a technology of membrane materials.     

Phase equilibria in the BaB<Subscript>2</Subscript>O<Subscript>4</Subscript>-NaF system

Phase equilibria in the BaB₂O₄-NaF system have been studied by a modified visual thermal analysis technique and differential thermal analysis. The phase diagram obtained in this study differs drastically from that reported previously. The system is shown to contain the primary crystallization field of a new compound, Ba₂Na₃[B₃O₆]₂F.     

A comparison of two analytical evaluation methods for educational computer games for young children

In this paper we describe a comparison of two analytical methods for educational computer games for young children. The methods compared in the study are the Structured Expert Evaluation Method (SEEM) and the Combined Heuristic Evaluation (HE) (based on a combination of Nielsen’s HE and the fun-related concepts from Malone and Lepper) with both usability and fun heuristics for children’s computer games. To verify SEEM’s relative quality, a study was set up in which adult evaluators predicted problems in computer games. Outcomes based on thoroughness (whether the analytical method finds all problems), validity (whether the analytical method uncovers problems that are likely to be true) and appropriateness (whether the method is applied correctly) are compared. The results show that both the thoroughness and validity of SEEM are higher than the thoroughness and validity of the Combined HE. The appropriateness scores indicate that SEEM gives evaluators more guidance when predicting problems than the Combined HE does.

Using computer simulation to determine operations policies for a mechanised car park

Using mechanised car parks to solve increasing parking demands is a relatively new concept. Processing a high number of clients each day ensures profitability, therefore time effective service which depends on efficient equipment and operations is vital for optimum car storage and retrieval. In focusing on a mechanised car park of known design characteristics (in the design phase) we identify factors that affect its operation, and use a discrete-event simulation model to evaluate proposed operations policies for efficiency. Simulation is shown to be a powerful tool for resolving complex, stochastic real-world problems.