Correlation relations between the parameters of the empirical dependences of some strength and diffusion characteristics on test conditions

Experimental data are often approximated by two-parameter relations in the form of a power or an exponential function. When a number of similar objects are considered, the parameters of these relations are connected by a correlation dependence. The examples of empirical relations where this dependence is observed are considered. In all cases of this correlation dependence, the value of an approximating function changes by several orders of magnitude when its argument varies by several times, and the initial data for the calculation of the empirical-equation parameters are located in a relatively narrow band in the coordinate space. This behavior is always accompanied by a linear relationship between the empirical coefficients of the equations obtained for a number of similar objects.     

An orthogonal basis for the hyperbolic hybrid polynomial space

Motivated by the wide usage of the Tchebyshev basis and Legendre basis in the algebra polynomial space, we construct an orthogonal basis with the properties of the H-Bézier basis in the hyperbolic hybrid polynomial space, which is similar to the Legendre basis and holds remarkable properties. Moreover, we derive the transformation matrices that map the H-Bézier basis and the orthogonal basis forms into each other. An example for approximating the degree reduction of the H- Bézier curves is sketched to illustrate the utility of the orthogonal basis.     

A system for real-time measurements of current-density distribution in low-energy electron beams with large cross sections

A system for real-time measurements of the current-density distribution in electron beams ejected from large-area electron accelerators has been developed. The system, which is based on Faraday cups, a microprocessor, and a PC, is designed for measuring the parameters of the electron beams ejected from large-area accelerators—devices for ionizing electroionization lasers and technological accelerators—and ensures real-time monitoring of the current-density distribution over the electron-beam cross section with a relative measurement accuracy of at least ±2%.     

The research seminar on computer algebra in 2005–2006

An annual report on meetings of the scientific research seminar on computer algebra is presented.     

A systematic approach for product families formation in Reconfigurable Manufacturing Systems

The aim of this work is to establish a methodology for an effective working of Reconfigurable Manufacturing Systems (RMSs). These systems are the next step in manufacturing, allowing the production of any quantity of highly customised and complex products together with the benefits of mass production. In RMSs, products are grouped into families, each of which requires a system configuration. The system is configured to produce the first family of products. Once it is finished, the system is reconfigured in order to produce the second family, and so forth. Therefore, the effectiveness of a RMS depends on the formation of the best set of product families. Therefore, a methodology for grouping products into families, which takes into account the requirements of products in RMSs, is an issue of core importance. These requirements are modularity, commonality, compatibility, reusability, and product demand. The methodology starts by calculating, for each product requirement, a matrix that summarises the similarity between pairs of products. Then, through the use of the AHP methodology, a unique matrix that comprises the similarity values between products is obtained. The Average Linkage Clustering algorithm is applied to this matrix in order to obtain a dendogram that shows the diverse sets of product families that may be formed.     

Investigation of a compound concentrator with a quasi-parabolic guide

A compound concentrator guide has been investigated that provides uniform energy distribution over the receiver. The values of the focal parameters of the parabolas that form the quasi-parabolic guide curve have been determined. The parametric equations of the curve along which the parabolas foci travel have been set up. Arrangement variants of the guide curve branches have been considered, and the compound concentrators have been assessed.     

Selecting optimum density of lattice of blades of screw pump impeller

A method is proposed for calculating the optimum density of lattice of blades of screw pump impeller that ensures, for a given cavitation margin (inlet pressure), the first critical condition on the partial cavitation characteristic of the pump. The equations obtained can be used also to calculate the permissible cavitation margin of screw centrifugal and screw mixed-flow pumps as well as of stand-alone screw impeller, provided the geometric and operating conditions of the screw are given. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 6, pp. 29–33, June, 2007.     

Gigabit pulse position bistability in semiconductor lasers

The paper briefly reviews the major forms of optical bistability in active optical devices compatible for use in gigabit optical communication systems, and reports an entirely new optical bistability for the first time. Unlike previous devices, the two bistable states of the optical device are each a series of picosecond optical pulses at 1 GHz or greater repetition rates, and are distinguished by a half period temporal shift between their temporal positions in relation to a clock pulse. The bistable device is based on a gain switched semiconductor laser. Theoretical studies suggest 100-ps switching speeds might be achieved, and experimental results are reported indicating optically triggered switching times of 500 ps.