Superconductivity effects near the metal-insulator transition in granular indium films

The paper reports on an investigation of the electric resistance as a function of temperatureT, magnetic fieldH, and applied voltageV in granular indium films when approaching the metal-insulator transition (MIT) due to increased thickness of the oxide layers between granules. The dependences are shown to be governed atT5 K by competition of the hopping conductivity and the Josephson tunneling of electrons, sometimes giving rise to a resistance minimum inR(T) associated with superconductivity. It was also found that even when the intergranular Josephson tunneling is totally suppressed, transition of granules to the superconducting state influences essentially the dependencesR(T, H), changing the functional form ofR(T) and resulting in anomalously high negative magnetoresistance. This is shown to stem from the change of the character of activated electron tunneling as the granules become superconducting.     

Heat transfer in the laminar-wave section of condensation of a stationary vapor

A method is proposed that specifies and refines the relation for the average coefficient of heat transfer at Re 250.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 52, No. 6, pp. 907–909, June, 1987.     

Erosion of unfilled elastomers by solid particle impact

The response has been studied of eight unfilled elastomers (four natural rubber compounds, epoxidized natural rubber ENR50, butyl rubber, polybutadiene and polyurethane) to erosion by 150 m silica sand at an impact velocity of 48 m sec^–1. All were tested at an impact angle of 30°, close to the impact conditions occurring in pipe bends, while two were also tested at 90°. Wide variations in erosion rate were observed between different rubbers. These differences did not correlate systematically with the nature of the base elastomer, glass transition temperature or mechanical properties such as hardness, tensile strength or ultimate tensile elongation, nor with resistance to abrasive wear. Good correlation was, however, found with rebound resilience. A high resilience tended to imply high erosion resistance, The erosion rate was found empirically to be proportional to the quantity (1 - fractional resilience) raised to the power 1.4. Different surface morphologies were found in specimens of high and low resilience after erosion at 30°. Finely spaced transverse ridges formed on high-resilience rubbers, whereas surface features on low-resilience rubbers showed no directionality. Preliminary conclusions are drawn about possible mechanisms of material removal.     

Methods for suppressing the longitudinal instability of a bunched beam with the help of landau damping

Conclusions The insertion of an additional accelerating system with multiplicity nq is desirable only in a synchrotron with a well-bunched beam, where the natural nonlinearity A ₀ ² is small.When the amplitude of the additional voltage is limited by the quantity nV_n/V_o1, there are two approximately equivalent schemes for switching on the harmonics nq (see Secs. 3 and 4), which permit obtaining an instability suppression factor of _max10/A _o ² with n_opt5/A_o.The efficiency of both schemes has been confirmed experimentally in ISR storage rings [1, 5], but there are no data for making quantitative comparisons of the experimental results with our calculations. At the same time switching on the harmonic n=2 in the PSB synchrotron without satisfying the condition (39) only increased the longitudinal instability of the beam [6].By raising significantly the amplitude of the additional voltage in the state of Sec. 3, which is equivalent to transferring to an acceleration multiplicity nq while keeping constant the number of bunches, it is possible to raise the instability suppression factor to _max 5/A _o ² with n_opt2.3/A_o[nV_n/V_o]^1/4.Translated from Atomnaya Énergiya, Vol. 62, No. 2, pp. 98–104, February, 1987.     

Evaluation of the parameters of an experimental tokamak fusion-reactor and the influence of the indeterminacy of the plasmaphysical data

Conclusion Analysis using a simplified technicoeconomic model of a tokamak reactor and the procedures of graphic processing of the results allow the regions of the optimum parameters of an experimental minimum-cost reactor with various limitations to be determined. When refined and ignition scalings are taken into account simultaneously and an appropriate optimization is made we get the parameters of the experimental reactor, which differ slightly from the basic variant (in particular, a lower neutron load on the first wall). The reactor cost in this case should increase by 15–25% in comparison with the basic variant and remains virtually constant when the most favorable ignition scaling (ASDEX) is realized.Translated from Atomnaya Énergiya, Vol. 62, No. 1, pp. 22–28, January, 1987.     

A theoretical and experimental investigation of the plastic deformation process of sintered composite materials. III. An investigation of the spatial redistribution of the phases of a composite material in plastic deformation of it

Conclusions As in porous bodies, in dense composite materials plastic deformations may cause an increase in the local concentration (density) of elements of the hard phase in zones of active flow of the material. The intensity of structural rearrangement (regrouping) of the phases in a composite material is determined by the character of the relationship of the function of plasticity of the medium to the amount of the average (hydrostatic) stresses in the body being deformed and is related to the degree of deformation obtained by this body through the derivative (_ij)/_ii. The mutual disposition of the elements of the hard phase in a material may be fixed in any stage of the process of working by pressure if the conditions are created for combined flow of the different phases in the body being deformed.Translated from Poroshkovaya Metallurgiya, No. 10(298), pp. 53–57, October, 1987.     

Evaluation of the possibility of mixing of turbulent jets with a comoving flow in a bounded space by interference methods

Experimental results showing the possibility of using interference methods for studying mass and heat-transfer processes in the combustion chambers of power generating installations with different configuration are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 2, pp. 181–185, August, 1987.     

Luminescent Properties of Glasses Based on Lithium Tetraborate Doped with Sm3+ and Gd3+

Glass Physics and Chemistry - Glasses based on lithium tetraborate obtained by solid-phase synthesis and doped with earth elements Sm3 +, Gd3 + have been investigated. The absorption and...     

Effect of alloying with rare earth metals on the recrystallization temperature and properties of aluminum and an alloy of the system Al-Cu-Mn

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 40–43, April, 1990.     

Water-Acetonitrile Ratio in Perchlorate Cadmium Bath and the Effectiveness of the Addition of Crown-Ester

It is shown that the strongest deceleration of the electrodeposition of cadmium in inhibited media is observed in the domain of loosening the structure of a mixed solvent (0.45 x ₂ 0.25) when the molecular adsorption of organic solvent on Cd is maximum. The process is maximally facilitated in the domain of ordering the acetonitrile's (AN) structure (0.9 x ₂ 0.75), where perchlorate anions dominate at the cathode surface. Crown-ester exhibits maximum inhibition effect under the conditions of preferential adsorption of its molecules, i.e., in the domain of the prevalence of the nonaqueous component in the mixture (x ₂ 0.95).