Industrial applications of heat transfer enhancement: The modern state of the problem (a Review)

Methods used for enhancing heat transfer in power installations and industrial thermal engineering apparatuses are reviewed. Classification of these methods is given, and the corresponding types of intensifiers are considered.     

Analysis of half-spin particle motion in Reissner–Nordström and Schwarzschild fields by the method of effective potentials

The paper presents an analysis of effective potentials of Dirac equations in Schwarzschild and Reissner–Nordström fields. It is shown that in the majority of the explored cases the condition of a particle “fall” to the corresponding event horizons is fulfilled. An exception is one of the solutions with a normalizable wave functions for the Reissner–Nordström extreme field, for which the existence of a stationary bound state of a half-spin particles is possible inside the event horizon.     

Errors in determining coal quality

Errors in determining coal quality are compared. For the example of the ash content, it is shown that the error in forming the samples is almost an order of magnitude greater than the error in sample analysis. The metrological characteristics and conditions of correct utilization of results from coal analysis are considered in the light of GOST R ISO 5725 standards. The correct comparison of results obtained by different methods is described.     

Development of ultra–low highly active and durable hybrid compressive platinum lattice cathode catalysts for polymer electrolyte membrane fuel cells

A highly active and stable catalyst/support system is developed by using a two-step process. In the first step, activated carbon composite support (ACCS) is synthesized that retains its activity after accelerated stress test (AST). A 30% Pt/ACCS catalyst shows no loss of mass activity and power density after 5000 cycles at 1.0–1.5 V while the commercial Pt/C and Pt/290G catalysts show drastic mass activity losses (57.5% and 66.2%, respectively) and power density losses (88.7% and 84.0%, respectively). In the second step, Pt catalyst with a compressive Pt lattice (Pt¹) is synthesized through a USC-developed annealing procedure in which Co atoms previously embedded in the support diffuse into Pt. The 30% Pt¹/ACCS shows high initial power density (rated) of 0.174 g_Pt kW^?1 and high stability of 24 mV loss at 0.8 A cm^?2 with an electrochemical active surface area (ECSA) loss of 42% after 30,000 cycles (0.6–1.0 V). The support stability under 1.0–1.5 V potential cycling shows potential loss of 8 mV at 1.5 A cm^?2 and ECSA loss of 22% after 5000 cycles. Improved stability and activity of Pt*/ACCS catalyst are due to synergistic effect of catalytic activity and stability of ACCS and formation of compressive Pt lattice catalyst.     

Surface microgeometry of powder coatings in slipping friction: A Markov approach

The formation of wear-resistant powder surface coatings with slipping friction may be described by a statistical approach based on continuous Markov processes. The coordinates of the equilibrium frictional surface are shown to be normally distributed. The correlation of the parameters of surface wear is investigated.     

Amplification of plasma waves in shielded active graphene

Amplification of plasma waves in shielded graphene with inverted energy distribution of charge carriers is investigated theoretically. It is shown that graphene shielding allows one to increase an amplification factor of terahertz plasmons in several times compared to the case of amplification of unshielded plasmons due to strong field confinement of the shielded plasmons near graphene.     

Stability of Plane-Parallel Pulsational Flow of Two Miscible Fluids under High Frequency Horizontal Vibrations

Linear stability of plane-parallel pulsational flow of two miscible fluids in a horizontal layer subjected to high frequency horizontal vibrations is investigated neglecting viscosity and diffusion. Long-wave instability is studied analytically and instability to the perturbations with finite wavelength—numerically.     

Effect of thermal annealing on the properties of borophosphate systems containing simulated Cs + Sr radioactive waste fractions

The effect of thermal annealing on the resistance of borophosphate systems to crystallization and the effect of crystallization on the hydrolytic stability of the materials were examined. Systems containing simulated Cs + Sr fraction were studied. Annealing at 400–500°C leads to a noticeable decrease in the leach rate. Annealing at a higher temperature, 600°C, leads to crystallization of the glass and to a considerable increase in the leach rate.