Critical Heat Flux in Vertical Steam-Generating Channels in the Absence of Circulation of Heat-Transfer Agent: Critical Power of Channels of Different Shapes

An experimental investigation is performed of the critical heat flux in vertical channels in the absence of circulation of heat-transfer agent through the lower cross section. Experiments are performed in tubes 30, 40, and 80 mm in diameter, as well as in 19- and 40-rod assemblies. Equations are suggested for the calculation of critical power, which are valid in a wide range of the geometric and process parameters, including at a low pressure.     

A millimeter-wave oscillator on an avalanche diode

A design and characteristics of the millimeter-wave oscillator (6–8 mm and 5–10 mW) on an 2A717б avalanche diode are described.     

The hydrodynamics of countercurrent two-phase flow in vertical channels

Countercurrent flow of gas and liquid in vertical tubes is investigated. Processes that occur under various conditions of flow (including the “flooding” mode) are treated. Equations are suggested that describing the hydrodynamic characteristics of countercurrent two-phase flow.     

Schoenberg’s polynomial B-splines. A short summary of applications

A short summary of applications for Schoenberg’s polynomial B-splines in statistical radio engineering and mathematical statistics is provided. Positive sides of Schoenberg’s B-splines are specified; advisability of their wider application is noted. Literature where exact formulas for Schoenberg’s B-splines of several minimal orders is listed.     

Energy Characteristics of the Two-Channel Scintillation Spectrometer

Instruments and Experimental Techniques - A two-channel scintillation spectrometer with a thickness of 0.5X0 was calibrated using cosmic muons and a beam of secondary quasi-monochromatic electrons...     

Laminar burning velocities of rich near-limiting flames of hydrogen

In the present work, near-limiting hydrogen flames were investigated both experimentally and numerically. Very rich hydrogen + air flames were studied in a constant volume bomb equipped with a pressure sensor and a Schlieren system for optical registration of the flame front movement. The mixtures contained 70% and 75% of hydrogen, the rest being air. The measurements were conducted at pressures from 1 to 4 atm for 70% H₂ + air mixture and from 0.7 to 1.4 atm for 75% H₂ + air mixture. Two methods for determination of the laminar burning velocity were used: from the temporal evolution of the flame front movement and from the pressure records at nearly constant pressure. These methods were compared and discussed in terms of accuracy and implicit assumptions behind them. Markstein lengths were also extracted and compared with the literature by using different extrapolation models. An important role of the critical radius for extraction of the burning velocity and Markstein length is demonstrated. New experimental data are compared with three models for hydrogen combustion to elucidate the need for their further development.     

Quantitative analysis of endohedral metallofullerenes by Rutherford backscattering of protons

Samples containing endohedral metallofullerenes of gadolinium (Gd@C₈₂) and dysprosium (Dy@C₈₂) are investigated by the Rutherford backscattering of protons. It is shown that the concentration of endohedral metallofullerenes can be determined to within a few percent. The measured concentration of endohedral metallofullerenes Gd@C₈₂ and Dy@C₈₂ in samples prepared by selective multistep extraction is ∼60%. Pis’ma Zh. Tekh. Fiz. 25, 24–30 (May 26, 1999)     

Production of steel of K65 strength class

The production of steel of K65 strength class at OAO Magnitogorskii Metallurgicheskii Kombinat is considered. The technology permits the production of steel with no more than 0.002% S, 0.012% P, and 0.006% N.     

Physicochemical modeling of interactions in the passive oxide film of an alloy. Thermodynamic model of a regular solution of oxide “molecules”

A physicochemical model of interactions between the components of a mixed oxide, which is equilibrium to the corrosive solution, is proposed as the first step to a theory of reciprocal effect of the components of a passive layer. Proceeding from the kinetic-electrostatic model of the passive metal developed earlier with the participation of the author and the classical theory of regular solutions and setting the quantitative relations between the concentrations of components in the alloy and in the solution, the model proposed forms a basis for modeling the dissolution kinetics of the components of a passive alloy. Some methodological aspects of describing the above interactions and correspondingly modifying the theory of regular solid solutions are discussed. The work was financially supported by the Russian Foundation for Basic Research, projects nos. 96-03-33978 and 99-03-32478a.