Communication Network Availability Predictions Based on Measurement Data

Published data describing the probability distributions of data communication system reliability parameters such as availability are very sparse. This paper describes a set of data collected in order to model communication line availability by monitoring operational communication systems. Probability distribution functions for single line availabilities and for the durations of failures are given. A heuristic model for estimating availabilities for more complex systems is presented along with computer simulation data validating the accuracy of the model. The results presented make possible more realistic availability predictions for common types of networks than have previously been computable.     

Composition and submicron structure of thin films of supersaturated Zn x Pb1 − x S solid solutions

Thin films of supersaturated Zn _x Pb_{1 ? x} S solid solutions containing up to 4.1 mol % ZnS have been obtained by hydrochemical deposition. The dependence of the material structure and surface morphology on the film composition has been studied. It is established that an increase in the content of zinc sulfide leads to the growth of grains with a more complicated crystalline structure, the formation of grain boundary fragments with dimensions from 60 to 100 nm, and a modification of the electrical properties of deposited layers.     

Effect of a convoluted gas flow on the movement of disperse phase in a rotary mass exchanger

The structure of a convoluted gas flow in a rotary mass exchanger is investigated. Profiles of the local-velocity distribution, and experimental functions for their calculation are obtained. A system of differential equations, the solution of which by the Runge-Kutta-Felberg numerical method made it possible to plot the trajectories of moving drops of a disperse liquid in a mass-force field, is compiled. __________ Translated from Khimicheskoe i Neftegazovoe Mashinostroenie, No. 3, pp. 9–10, March, 2007.     

Heating of a gas and a polymeric material in low-temperature plasma of a high-frequency discharge

High Temperature - A model of the thermal process in high-frequency capacitive discharge plasma of low pressure in air is considered. The influence of the discharge power and pressure on the...     

Ellipsometry of chemically deposited PbS-ZnS films

The optical and dielectric characteristics of hydrochemically deposited films of lead sulfide (PbS) and supersaturated substitutional solid solutions of the PbS-ZnS system have been studied by the ellipsometry techniques. It is established that the formation of solid solutions leads to an increase in the refractive index and a decrease in the imaginary part of the complex dielectric constant as compared to those of pure PbS films. An increase in the content of ZnS in the solid solution us accompanied by a significant decrease in the dielectric loss tangent.     

Abnormal manifestation of the high-temperature degradation of the weld metal of a low-alloy steel welded joint

We have shown that hardness, impact toughness, mechanical properties in tension, and the local parameters of fracture mechanics (static and cyclic crack resistance) are sensitive to the operating degradation of weld metal of steam pipelines of thermal power plants made of 15Kh1M1F steel. The simultaneous decrease in the resistance to brittle and plastic fracture (hardness, strength, and impact toughness) represents a phenomenon of the operating degradation of weld metal. We have established a specific correlation between the characteristics of plasticity and other mechanical parameters of operated metal: the increase in °₅ of operated weld metal is in good agreement with the decrease in its strength, whereas the reduction of Ψ correlates with the lowering of resistance to brittle fracture. Electrolytic hydrogenation decreases the characteristics of strength and plasticity of operated weld metal much stronger than in the initial state. The absence of ferritic edgings on the boundaries of primary austenitic grains makes for a low resistance to brittle fracture, and the change in acicular ferrite deteriorates the mechanical properties. The ductile fracture of nonoperated metal is replaced by brittle intercrystalline failure in operated metal. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 1, pp. 73–79, January–February, 2007.