Enhancement of heat and mass transfer in a plane channel with turbulizers on one of the walls

The effect of turbulizing asperities positioned on one of the walls of a plane channel on the intensity of exchange processes near a smooth wall with injection of different working media is studied experimentally. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 404–408, 1997.     

Determination of Discrete-Structure Parameters of Coatings with Allowance for Residual Stresses

The authors suggest that the dimensions of a discrete section of a coating should be chosen on the basis of calculation of the critical crack spacing in cohesion cracking. This approach allows for residual stresses in the coating. The reliability of the calculation method has been verified experimentally by direct measurement of the crack spacing.     

Longitudinal vibrations of a rod with a coating

A solution is obtained to the problem of the longitudinal vibration of a rod with a coating. The solution is obtained in a refined formulation. The same theoretical model is also used to find the solution for the case of static tension. An analysis is made of the way in which the properties of a deformable rod are affected by the stiffness of the shear constraints, which is regarded as a physicomechanical characteristic of the coating-substrate system. A method is proposed for experimental determination of stiffness for both static and cyclic loading conditions. All of the relations needed to analyze the stress-strain state are presented, including those required for fatigue tests in tension-compression.Translated from Problemy Prochnosti, No. 10, pp. 68–75, October, 1994.     

Dynamic thermal methods and microprocessing units for measuring the rates and properties of material flows

A multifunctional measurement system utilizing a noncontacting, thermal-tracer primary detector is described. It provides for the automatic acquisition of information on volumetric and mass flow rates and the properties of fluid flows.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 10–11, August, 1994.     

Use of a ductile fracture model for pipes with axial defects for analysis of results of full-scale experiments

We consider the use of a ductile fracture model for pipes with axial defects, loaded by internal pressure, for calculation of the limiting burst pressure P_LL. We describe procedures for hydraulic and pneumatic testing of full-size pipes performed at VNIIST (All-Union Scientific Research Institute for the Construction of Trunk Pipelines, Moscow), and also the scheme for application of a surface notch. We have done a comparative analysis of the value of P_LL calculated from the relationships determined on the basis of a ductile fracture model for cylindrical bodies with cracks and the value obtained using familiar empirical formulas. Based on the calculations, we plot graphs for the distribution of the deviation of the calculated burst pressure from the true burst pressure as a function of the relative crack length ². We demonstrate the considerable effectiveness of the ductile fracture model for pipes with defects, which allows us to take into account the real shape of the defect and additional mechanical actions (longitudinal forces, bending moments).Translated from Problemy Prochnosti, No. 6, pp. 5–15, November–December, 1996.     

Multimedia information technologies in education: Basic concepts,essence, and typology (Review)

This paper reviews and discusses the concepts found in domestic and international literature on the use of multimedia and other related technologies, including the author’s experience in librarian education.     

A model of grain boundary sliding during deformation

A model of slip at grain boundaries is proposed based on the concept of local melting of the grain boundary under intense external influence and by analogy with ultrathin lubrication. A discontinuous regime of slip along the grain boundaries similar to the stick-slip process in thin lubricants is described.     

Composite materials of diamond–(Co–Cu–Sn) system with improved mechanical characteristics. Part 2. The influence of CrB<Subscript>2</Subscript> additive on the structure and properties of diamond–(Co–Cu–Sn) composite

The structural alterations in the diamond–metallic binder transition zone in the diamond(78.4Co–11.76Cu–7.84Sn–2CrB₂) composite upon its sintering in a mold in hydrogen atmosphere at 800°C for 1 h have studied versus the hot re-pressing parameters, and the influence of such alterations on physical-mechanical and tribological properties of the composites has been clarified. Adding 2 wt % CrB₂ to the starting diamond?(80Co–12Cu–8Sn) composite is shown to raise the ultimate compression strength from 816 to 1720 MPa, bending strength from 790 to 1250 MPa, and wear resistance by a factor of 2.4. The improvement of properties of the composite and the increase of its wear resistance are provided due to the formation of Cr₃C₂ nanocarbide in the transition zone and the uniform distribution of Co, CrB₂ phases and CoSn inclusions in the volume of the metallic binder.