Monolithic Integrated Circuits Based on Gallium Nitride for Short-Range Radar and Communications in the 22–25 GHz Frequency Range

Russian Microelectronics - A set of monolithic integrated circuits (MICs) in the 22–25 GHz range based on gallium nitride nanoheterostructures on sapphire substrates is designed, produced,...     

Experience in the ultrasonic testing of fastening studs in the covers of hydraulic units at hydroelectric power plants

The criteria for evaluation of the admissibility of discontinuity flaws under the threads of studs during their inspection from the end face without unscrewing them from their seat in a hydraulic unit frame are experimentally substantiated. A transducer with the optimal parameters that allows one to reveal cracks of minimal depths is selected. Ultrasonic inspection of studs with a hexahedron at the end face is used as an example and the results of the ultrasonic testing of studs with detected cracks are presented.     

Selecting a retrofitting profile for the TGME-444 boiler at the Rostov TETs-2 cogeneration station

Hydraulic misalignments in the steam superheating surfaces and possible changes in the thermal circuit of a TGME-444 boiler are analyzed, and the retrofitting version of this boiler that was drawn up from the results of this analysis and implemented at the Rostov TETs-2 cogeneration station in 2007 is presented. The improvement in the operational reliability of the retrofitted boiler is demonstrated.     

Electronic Inhomogeneity and Possible Pseudogap Behavior of Spin Susceptibility in the Electron-Doped Superconductor Sr0.93La0.07CuO2: 63Cu NMR Study

The magnetic susceptibility, NMR spectra, nuclear spin-lattice relaxation rate (T ₁ ^–1) and the echo-decay rate (T ₂ ^–1) of ⁶³Cu were measured for the electron-doped infinite-layer superconductor Sr_0.93La_0.07CuO₂/T _c ^onset = 42.4 K). The results obtained revealed a clear tendency toward frustrated phase separation in this nominally underdoped high-T _c material. Above T _c the ⁶³Cu Knight shift is found to decrease upon cooling giving an evidence for a pseudogap-like decrease of the spin susceptibility. It is shown that unusual anisotropy of the ⁶³Cu Knight shift in the electron-doped CuO₂ layer can be understood as a compensation effect between the isotropic hyperfine coupling, mediated by the 4s Fermi-contact and 3d core-polarization exchange interactions, and the anisotropic on-site spin-dipolar hyperfine interaction of the Cu nuclei with the itinerant carriers, whose states near the Fermi energy have a sizeable admixture of Cu(4p_z) and/or Cu(3d_z ²) orbitals.     

Increase in the operating efficiency of heating units using ceramic fibers and objects based on them

The operating efficiency of heating units using ceramic fibers and objects based upon them is demonstrated: furnace warm-up time and cooling is saved by a factor of five, there is an overall reduction in fuel consumption with the use of light-weight objects in continuously operating furnaces by 10 – 15%, and in periodically operating furnaces by 45%, and there is a reduction in capital expenditure in furnace construction by a factor of 5 – 10 (according to USA data). In addition, use of thermal insulation materials not only saves energy resources, but in many cases it speeds up production processes, improves ecology, and simplifies lining construction.     

Calculation of Minimum Particle Mixture Fluidization Velocity in a Wet Biomass Torrefaction Reactor

Chemical and Petroleum Engineering - A simple method is proposed for calculating the minimum velocity of fluidization of a bed consisting of particles differing considerably in shape and size. The...