Computational-theoretical investigation of buoyant jet flows

The results of mathematical simulation of fully developed plane buoyant jet flows are presented. The solution is found within the framework of the model of a laminar boundary layer in the Boussinesq approximation using the method of matched asymptotic expansions. Analytical dependences of the basic characteristics of a jet flow on the Prandtl number and density parameter have been constructed.     

Asymptotics of eigenvalues for the Laplace equation in domains with slots

The asymptotic formula for the eigenvalues of the Laplace equation in three-dimensional domains bounded by a finite number of closed and open nonintersecting Lyapunov surfaces with smooth boundaries has been derived. This result is of importance in calculating stationary thermal conductivity in solid bodies in the presence of slots in them. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 577–582, May–June, 2008.     

Intelligent Computation of Moisture Content in Shrinkable Biomaterials

A technique of intelligent computation of moisture content in shrinkable biomaterials from multiple predictors was developed. All measurable predictors were structured in three sets: biomaterial properties (volume, density, porosity, diffusivity); drying conditions (time, air temperature, humidity, velocity, pressure); and drying technologies. Two typical drying models were considered: time-dependent (thermodynamical) and time-independent (relational). The relationship between predictors and moisture content was established on the basis of multi-factorial linear regression (MLR) and neural networks (NN). Accuracy of statistical approximation was strongly dependent on drying model and chosen set of predictors. Time-independent models demonstrated better accuracy (MSE = 0.214) than time-dependent models (MSE = 0.254). Redundant predictors did not affect the accuracy and generalization ability of statistical models.

Results of NN training and testing showed superior accuracy with respect to statistical models. NN worked perfectly well for any combination of non-correlated predictors, improving accuracy to MSE = 0.01. Elimination of redundant predictors further improved accuracy and generalization ability of NN models.

The performance of both models was tested for drying of ginseng roots in the range of temperatures from 38 to 50°C, sizes from 10 to 32 mm, and relative humidity from 12 to 40%. Due to the high accuracy and computational efficiency, NN can be used as online estimator of moisture content in drying process.     

Advanced refractory articles and materials for the metallurgical industry

Data on some novel kinds of refractory articles and materials developed and produced by the Berezhnoy Ukrainian Research Institute for Refractories (Berezhnoy UkrNIIO) are presented. Corundum articles with Sialon binder and unshaped materials of various kinds (ramming mixtures, dry mixtures, traditional and low-cement refractory concretes) containing normal electrocorundum or refractory scrap instead of the costly white electrocorundum are described. __________ Translated from Novye Ogneupory, No. 11, pp. 59–63, November, 2007.     

Comparison of the Results of Field Radiometry and Sampling in the Investigation of 137Cs Soil Content in Bryansk Oblast

It is suggeted that field radiometry be used for real-time examination of the radioactive contamination of soil. It is shown that the accuracy and representativeness of the measurements performed with a portable 256-channel gamma spectrometer (RKG-09N) using a collimated detector is higher than that the method of extracting and analyzing soil samples. The results of a comparison of measurements of the ¹³⁷Cs contamination of soil, which were obtained using field radiometry, and soil sampling data for 16 sites at the Scientific and Industrial Association Taifun in Bryansk oblast are presented in detail. The variability of the ¹³⁷Cs content within the sampling site (~2 m²) in anthropogenic and virgin soil in different landscapes is estimated.     

Advanced Refractory Products and Materials Developed at the A. S. Berezhnoi Ukrainian Research Institute for Refractories Joint-Stock Co.

A brief survey of R&D activities carried out at the A. S. Berezhnoi Ukrainian Research Institute for Refractories (UkrRIR) Joint-Stock Co. is presented aimed at the output of unique high-tech refractory products for metallurgical, machine building, glass-making, petrochemical, and other branches of industry. A wide range of products recently developed and/or commercially available is considered: refractory components of different size and shape — mullite-corundum, corundum with zircon added, chromium oxide, periclase-lime-carbon, silicon carbide, zirconia, high-efficient lightweight calcium hexaaluminate and anorthite-based composites, concrete and ramming mixes of corundum zirconia, mullite-corundum, mullite-silica, chamotte and silicon carbide composition (low-cement included).