Hybridization of acoustic waves in piezoelectric plates

The conditions for hybridization of the zero-order and high-order acoustic waves propagating in a piezoelectric crystal plate have been studied. The dependence of the phase velocity of the hybrid waves on the parameter hf (h is the plate thickness and f is the wave frequency) is established for the potassium niobate and lithium niobate plates possessing various crystallographic orientations and conductivities. It is found that hybridization takes place when the conductivity of a thin surface layer exceeds a certain critical value, which can vary within broad limits depending on the plate material and orientation. The degree of dispersive repulsion of the coupled modes grows with increasing electromechanical coupling coefficient.     

Increasing the corrosion resistance of low-alloy and carbon steels for automobile construction by optimizing the metallurgical technology

It is shown that the corrosion resistance of automobile sheet can be improved by ensuring that steels of this type have a low content of corrosion-active nonmetallic inclusions (CANI). The main mechanisms responsible for the formation of CANI in automobile sheet have been established, and recommendations have been developed to reduce their concentration in this product • optimize the deoxidation processes that are used by ensuring that the proportions of the additions made to the steel are consistent with the composition of the ladle slag and that certain key temperature-time parameters of these processes are maintained • control the composition of the ladle slag to prevent the formation of solid phases in the slag and their transfer to the metal; certain conditions must also be observed in the argon blow and the introduction of the addtions. Use of the above recommendations to make automobile sheet and tube steels cleaner with respect to their content of CANI and thus help optimize out-of-furnace treatments at metallurgical and pipe plants will make it possible to improve the corrosion resistance of metal products used in automotive manufacturing. __________ Translated from Metallurg, No. 2, pp. 45–48, February, 2006.     

Statistical analysis of the amplitudes of random stresses

A study is made of the distribution law for the amplitudes of random stresses and associated parameters. A theoretical law is proposed to describe an empirical distribution, and a comparison is made between the deviations of the endurances corresponding to these laws and the coefficient of variation of random endurance values. An empirical formula is obtained to determine maximum stress amplitudes.Translated from Problemy Prochnosti, No. 3, pp. 63–70, March, 1994.     

Sequential optimization algorithms for complex extended construction projects

Conclusions Theoretical and practical results indicate that the SAA method can be efficiently applied for the solution of road construction optimization problems with allowance for construction dynamics.We have experimentally established the possibility of replacing the traditional static designs, based only on average initial data, with dynamic designs relying on accurate information about the current conditions. The dynamic designs can be used to develop the best managerial decisions for roadbed construction.Our results again emphasize the need for the development of a qualitatively new scientific-technical base of construction controls relying on integrated application of efficient mathematical methods and computing tools for the analysis and optimal revision of design, technological, and organizational solutions. Our research has led to the development (jointly with Glavbamstroi design office) of a proposal for a program of radical improvement of preparation in the construction industry by establishing an interactive link between CAD systems and MIS. The proposal has been approved by the college of the Ministry of Transportation Construction.This research is merely the first step toward the development of optimization algorithms for an integrated computerized management system for road construction, which should substantially accelerate the search for best design and managerial solutions by allowing sequential optimal revision of earlier alternatives in different stages of the life cycle of the project, strengthening the currently weak feedback from construction to design, and encouraging the experts to assume an active role in on-line search for the best man-machine solutions. Our results to a certain extent have stimulated the organization of design and construction associations, approved by the Resolution of the Central Communist Party of the USSR and the Council of Ministers of the USSR, whose function is to improve the economics of construction and in particular to accelerate large-scale adoption of research results in practice.In addition to the authors, many other researchers took part in this project: V. I. Biletskii (in the development of algorithms and programs and in running the line optimization computations for the longitudinal profile), V. V. Yatskevich (in improvement of programs and in running the earth mass distribution optimization), V. S. Belopol, I. A. Vasilevskii, G. M. Eremeev, E. V. Ivanov, A. P. Kozhevnikov, V. A. Maslov, Yu. B. Narusov, V. S. Plastun, I. S. Rozanov, A. A. Yakubov, V. F. Temnikov, V. A. Shamuratov, V. I. Avdonin, V. A. Baranov, and others (in substantive formulation of the problems, in organization of pilot work, in the analysis of the results, in the development of input data and generalization of the results).Translated from Kibernetika, No. 5, pp. 63–69, September–October, 1988.     

A triangular class of skew maximum-period polynomials

Skew maximum-period polynomials (MP polynomials) are a kind of pseudorandom sequence generators with good cryptographic properties and efficient implementation on modern processors using parallelism technologies. There are two known classes of MP polynomials, presented in various papers (actually coinciding, as will be shown below), obtained constructively. Here we describe a wider class of skew MP polynomials.     

Guaranteed accuracy of estimating the state vector of an unperturbed linear dynamic system

We propose a constructive algorithm for determining the guaranteed accuracy of estimating the state vector of an unperturbed linear dynamic system for an arbitrarily taken algorithm in the context of a problem with measuring errors that are limited in magnitude [1]. We also present the results of determining the measure of the guaranteed accuracy of estimation for the class of algorithms that minimize the Hölder norm.     

Inhibitor Petri net executing an arbitrary given Markov normal algorithm

An inhibitor Petri net with a fixed structure that executes an arbitrary given Markov normal algorithm is constructed. The algorithm and its input string are encoded by nonnegative integer numbers and put into dedicated places of the Petri net, which implements the application of the algorithm productions over the string of symbols. Rules of encoding sequential, branching, and cyclic processes by Petri nets are used. Upon completion of the net operation, the output string is restored (decoded) from the integer form of the representation. Within the paradigm of computations on Petri nets, the constructed net provides the compatibility of systems.     

Method of assessing diffusion coefficients from gas absorption by metal powders

Conclusions A simple experimental method is proposed for determining diffusion coefficients from amounts of gas absorbed by metal powders. An analysis is made of errors in the measurement of D by the new method, and optimum experimental conditions are indicated. Data yielded by a study of the diffusion of hydrogen in LaCo₅ show that D _H ²⁹³ LaCo₅ can be calculated by this method with satisfactory accuracy.Translated from Poroshkovaya Metallurgiya, No. 4(232), pp. 25–32, April, 1982.     

Preparation of magnetic glass-ceramics through glass crystallization in the Na2O-SrO-Fe2O3-B2O3 system

Glasses with the nominal compositions SrFe₁₂O₁₉ + nNa₂Sr₂B₄O₉ (n = 4, 6, 8, 10) and SrFe₁₂O₁₉ + 6Na₂Sr₃B₄O₁₀ were prepared via rapid quenching of oxide melts and were then heat-treated between 500 and 800°C in order to produce glass-ceramics containing fine SrFe₁₂O₁₉ particles. The materials were characterized by x-ray diffraction, differential thermal analysis, electron microscopy, and magnetic measurements. The crystallization behavior of the glasses was investigated. The coercivity of the glass-ceramics was shown to increase with heat-treatment temperature, up to 486 kA/m. By dissolving the nonmagnetic matrix of the glass-ceramics with the nominal compositions SrFe₁₂O₁₉ + 6Na₂Sr₃B₄O₁₀ and SrFe₁₂O₁₉ + 4Na₂Sr₂B₄O₉, submicron-sized strontium hexaferrite particles were obtained.