NADRA 3D information technology for analysis of processes in multicomponent soil media

This paper considers the principles of algorithmic and software implementation of the software system NADRA 3D designed to analyze processes in three-dimensional multicomponent soil media. The principles of operation of NADRA 3D are described. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 157–174, November–December 2006.     

Advanced Method for Single Crystal Casting of Turbine Blades for Gas Turbine Engines and Plants

A method for fabricating single crystal blades that combines the techniques of seed crystals and selection is suggested. The method realizes the advantages of both techniques, i.e., the high structural perfection and the possibility of fabricating single crystals with specified spatial orientation. Metallographic and x-ray diffraction analyses are used to study the processes of nucleation of the single crystal structure of blade castings fabricated from high-temperature nickel alloys by the method of selection and seed crystals. A commercial process for fabricating cast single crystal turbine blades by the new method is suggested.     

New phenothiazine dyes and pigments

The synthesis of three new azaphenothiazine ring systems and an evaluation of their use as intermediates for new dyes and pigments is described. 2-Amino-5-bromopyrazine-3[4H]-thione (11) was prepared and converted to the novel 1,4,6,9-tetraazaphenothiazine ring system. The reaction of 4,5-diaminopyrimidine-6[1H]-thione (15) with 2,3-dichloropyrazines gave the isomeric 1,4,6,8-tetraazaphenothiazine ring system, another new heterocycle in this series. With 2,3-dichloroquinoxaline a previously unknown tetracyclic tetraazaphenothiazine ring system was isolated in satisfactory yields. The properties and reactions of these new heterocyclic systems are presented. Mixed nitric and sulphuric acids convert them to their 5-sulphoxides. Structural assignments were based on chemical evidence and their UV, IR, NMR and mass spectra. Mechanistic pathways to these compounds are also proposed.     

Asymptotic analysis of queues in multiple-access computer networks

The paper considers local-area computer networks with a protocol that supports carrier-sense multiple access with instantaneous conflict detection and is a generalization of slotted ALOHA. An approach based on recurrent processes is applied to analyze the asymptotic behavior of the number of waiting calls under conditions of low retrial rate.Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 54–61, July–August, 1991.     

Fast algorithms for estimating the correlation functions of large signals

A fast algorithm is proposed for estimating the auto- and cross-correlation functions of a large signal. The algorithm is based on the sectioning method by the fast Fourier transform. We determine the optimal length of the portion of data read from external memory into RAM which achieves T_min—a minimum processing time. An estimate of T_min is obtained.Translated from Kibernetika, No. 3, pp. 78–81, May–June, 1991.     

Efficient mixed Timoshenko–Mindlin shell elements

The precise representation of rigid body motions in the displacement patterns of curved Timoshenko–Mindlin (TM) shell elements is considered. This consideration requires the development of the strain–displacement relationships of the TM shell theory with regard to their consistency with the rigid body motions. For this purpose a refined TM theory of multilayered anisotropic shells is elaborated. The effects of transverse shear deformation and bending‐extension coupling are included. The fundamental unknowns consist of five displacements and eight strains of the face surfaces of the shell, and eight stress resultants. On the basis of this theory the simple and efficient mixed models are developed. The elemental arrays are derived using the Hu–Washizu mixed variational principle. Numerical results are presented to demonstrate the high accuracy and effectiveness of the developed 4‐node shell elements and to compare their performance with other finite elements reported in the literature. Copyright © 2002 John Wiley & Sons, Ltd.