Cobalt doped glass for the fabrication of percolated glass–alumina functionally graded materials

The present research was focused on the development of a new glass to produce glass–alumina FGMs. The glass formulation, belonging to the CaO–ZrO₂–SiO₂ system, was doped with cobalt, by adding a small molar percentage (about 0.1 mol%) of CoO, in order to obtain a blue glass, which could be useful to appreciate the final compositional gradient. The glass was accurately characterized, evaluating its thermal behaviour, its mechanical properties, and its attitude to crystallize during a thermal treatment. Subsequently, the glass was used to produce glass–alumina FGMs via percolation and the so obtained specimens were analysed in order to evaluate the effect of the glass infiltration. The possible development of new crystal phases, in particular, was tested via micro X-ray diffraction and the elastic properties gradient associated with the compositional gradient was measured via depth-sensing Vickers microindentation.     

Theoretical Investigation of Metal Cladding for Nanowire and Cylindrical Micropost Lasers

We investigate the transverse modal properties of cylindrical subwavelength metal-clad nanowire and micropost lasers via rigorous theoretical waveguide analysis, including the effects of finite thickness metal cladding and gain in the core. The results of this analysis show that air-metal surface guided TM₀₁ and some hybrid surface guided modes suffer less loss but are less confined to the core, while core-metal surface guided modes are better confined to the core but suffer greater loss. An increase in the thickness of the metal cladding reduces the loss of the core-metal surface guided modes. The modal gain and confinement of the metal-clad cavity are compared to an unclad cavity.     

Optimum orientation of a nontracking solar concentrator

We present the results of research studying how long nontracking solar concentrators of a new type can operate in a day depending on the concentrating module tilt angle. We also analyze the possible drop in the concentrator’s output in case of using it in northern regions without correcting its orientation for a full year.     

PIK-2 Reactor with a Low Consumption of High-Enrichment Uranium

Calculations of the possibility of switching the matrix of the fuel-element cores and the vessel with the reactor envelope to weakly neutron-absorbing aluminum and lowering at the same time the fuel content in the fuel elements by 40% are performed for the high-flux PIK reactor which is under construction in Gatchina. As a result, the flux density of the thermal neutrons in the heavy-water reflector increases by a factor of 1.4–1.5 and the maximum unperturbed flux reaches a world record value – 1.9·10¹⁵ sec^–1·cm^–2. The nonuniformity of the volume energy-release decreases to 2.3. The weight of the control rods and reactor safety increase. As a result of the decrease of the fuel content in the fuel elements and the increase of the run duration, about 60 kg of high-enrichment uranium ²³⁵U are saved annually, decreasing annual fuel costs by one third.     

Specifics of initial steam condensation and its influence on corrosion damage in turbines

Processes of corrosion cracking of the metal of turbine blades in the region of initial steam condensation are considered. Possible ways of preventing corrosion-fatigue damage to the blades are proposed.     

Algebraic systems with locally varying matrices for control in electrical energetics: A solution method

Deterministic relations are used to design a method and an algorithm for solving algebraic systems of equations with locally varying coefficient matrices encountered in operational control problems in electrical energetics.     

Upgrade of Proportioning Colorant and Decolorizing Agents for Glass Batch

Different designs of proportioners and screw feeders for colorant and decolorizing agents for glass melt are discussed.__________Translated from Steklo i Keramika, No. 4, pp. 8 – 9, April, 2005.