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.     

Phase modulation of an electron flow in the case of large transit angles

Within the framework of a model allowing an analytic solution, the interaction of an electron with the field that is a superposition of a high-frequency (from millimeter- to light-wavelength) electric field and the electrostatic field is considered. The characteristics of the electron motion in the field are investigated as functions of the entrance phase. It is shown that the electron beam flowing through the region of the high-frequency field undergoes modulation that is determined by the phase of the electron entrance into the region of the high-frequency field. It is found that, for certain parameters of the system, the density of an electron flow in free space can effectively be modulated.     

Crack branching in carbon steel. Fracture mechanisms

The fracture surfaces of pressure vessels made of carbon steel that form during crack branching propagation are examined by fractography. Crack branching is found to occur at a crack velocity higher than a certain critical value V > V _c . In this case, the material volume that is involved in fracture and depends on the elastoplastic properties of the material and the sample width has no time to dissipate the energy released upon crack motion via the damage mechanisms intrinsic in the material under given deformation conditions (in our case, via cracking according to intragranular cleavage).