Assurance of uniformity of measurements of spectral and dispersion characteristics in fiber-optic information transmission systems with wavelength-division multiplexing

The state and problems involved in achieving the uniformity of measurements in the field of fiber-optic information transmission systems and their components are considered. Possible approaches to the solution of these problems and the basic methods and techniques that have been developed in Russia up to this point are analyzed. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 30–34, May, 2006.     

Non-alloy Cr/Au Ohmic contacts in the technology of planar beam-lead GaAs <Emphasis Type="Italic">p-i-n</Emphasis> diodes

The characteristics of non-alloy Cr/Au ohmic contacts in planar beam-lead GaAs p-i-n diodes have been studied. The room-temperature reduced contact resistance in the structures studied was 2 × 10⁻⁶ Ω cm². The obtained parameters of p-i-n diodes allow these devices to be used as limiters in radar protection systems.     

Effect of current pulse frequency on the structure and properties of electric-spark alloyed coatings of the Ti - Al - N system

The mass transfer kinetics, composition, structure, and properties of coatings, formed by high-frequency electric-spark alloying of 45 and 40X steels with the Ti - Al (3:1, 1:1, 1:3) intermetallics and TiN - AIN (1:1) nitride were studied as a function of the current pulse frequency(ν = 1200 and 1600 Hz). A decrease in ν was found to lead to a higher mass transfer coefficient and higher microhardness and Young’s modulus of the coating as well. This is due to the decrease in the Ti/Al ratio on the surface. The phase composition of intermetallic and nitride coatings differed only insignificantly and did not depend on the value of ν. The main phases of the coatings were Fe - Ti - O and Al - Ti - O solid solutions. The nitride and intermetallic coatings had similar friction coefficients f and wear rates I (f = 0.26 and 0.28, I = 5.4 and 5.9 µm/km), despite the difference in their structure. We can assume that the coating phase composition which defines the composition of the secondary structure under dry friction, is the main factor controlling tribological behavior.     

The impact of the composition of structural steels on their corrosion stability in liquid Pb-Bi at 500 and 400 °C with different oxygen concentrations

In recent years, heavy liquid metals have found exercise as possible coolants and targets in the conversion of radioactive elements in accelerator driven systems (ADS). Liquid lead-bismuth eutectic alloy is one of candidates for this using tanks to its suitable nuclear and physical properties. Performed examination was aimed at research of compatibility choice materials for parts of ADS with liquid Pb-Bi eutectic alloy, influence of composition choice materials on their corrosion resistance, influence of temperature and oxygen content. We performed corrosion tests of 1000 h each on approximately 20 types of structural steels (austenitic, ferritic and martensitic) in convection loops with flowing Pb-Bi at 500 and 400 °C and using different oxygen concentrations. The impact of Fe, Cr, Ni, Mn, Si, Al and Mo content on the corrosion stability of these steels was measured without and after preliminary passivation through creating thin spinel or oxide layers on their surface.     

Time-domain simulation of H-plane optical distribution systems for the development of wideband multibeam active phased antenna arrays

An H-plane optical distribution system for formation of a five-beam radiation pattern of active phased antenna arrays is proposed and analyzed. The distribution system is analyzed in time domain, which allowed obtaining the results on transient processes in this system.     

Adsorption of ethyl benzoate on activated carbon

The kinetics of adsorption of ethyl benzoate from solutions in ethanol on coconut shell activated carbon was studied. It was found that the kinetics of adsorption of ethyl benzoate can be described by pseudofirst-order and pseudo-second-order rate equations with the same accuracy. It was established that the adsorption isotherm at a concentration to 2 g/L in the initial solution is adequately described by the Langmuir equation.