Stochastic quasigradient method for optimizing the parameters of dynamic systems

Two-stage stochastic optimization of dynamic system parameters is considered. It is shown that the original optimization problem can be approximated with any degree of accuracy by a finite-dimensional minimax stochastic problem. An Arrow—Hurwicz type stochastic quasigradient algorithm is proposed for solving such problems.Translated from Kibernetika, No. 4, pp. 104–107, 130, July–August, 1990.     

Analysis of the Errors in Measuring the Thermal Characteristics of an Unbounded Plate by the Pulse Method

The errors in measuring the thermal diffusitivity and heat capacity by the pulse method are analyzed. The errors due to heat exchange, the finite dimensions of the plate and the length of the heat pulse, as well as distortions due to preliminary signal processing (filtering) are considered.     

Measurement of the thermal diffusivity by the thermal wave method using low-power heat sources

The errors in measuring the thermal diffusivity by the plane thermal wave method are considered as a function of the thermal flux power density. The minimum values of the thermal flux power density required for measurements with a specified error and the optimum parameters of the samples and of the heat source are determined. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 44–46, August, 2007.     

A Deuterium High-Pressure Target

A design of the deuterium high-pressure target is presented. The target of a 76-cm³ volume is intended to study muon-catalyzed fusion reactions in ultrapure D₂ (the concentration of impurities with Z > 1 is under 0.2 ppm) at temperatures of 80–800 K and up to 150-MPa pressures. The operation of the main target systems is described: the generation and purification of deuterium gas, refrigeration, heating, evacuation, control, and automated data acquisition. The target was used to determine the parameters of the muon-catalyzed fusion reactions in ultrapure D₂ at temperatures of 300 to 800 K and pressures up to 150 MPa.     

The errors in measuring thermal diffusivity by a pulsed method due to random fluctuations of the form of the laser pulse

An experimental estimate is given of the errors in measuring thermal diffusitivity by a pulsed method, due to random changes in the time distribution of the radiation of the pulsed laser. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 37–39, November, 2006.     

High-Temperature Pyrometric Measurement of Thermal Diffusivity by a Flash Method: Co–Si and Co–Ge Systems

The paper deals with an automated system for measuring the thermal diffusivity of metals and alloys by a flash method involving the use of a contactless technique of recording the superheat temperature of a specimen. The solution of the heat equation for a cylinder with due regard for the Gaussian distribution of energy over the laser beam cross section forms the basis of the measurement method. The structural scheme of the experimental facility is described using an IBM PC and a GOR-100M type laser. The results of measuring the thermal diffusivity of Co–Si and Co–Ge systems in the temperature range of 300–1650 K are presented. The polytherms of the thermal diffusivity in the vicinity of the Curie point and in structural transitions exhibit anomalies. These anomalies are smoothed out as the concentrations of Si and Ge increase, and are not observed at a concentration of admixtures higher than 10 at. %. The obtained results are in satisfactory agreement with the diagrams of state for Co–Si and Co–Ge alloys.