Use of waterless molding mixtures as a substitute for the traditional sandy-argillaceous mixtures

In the last years, there is carried out an intensive search for new molding mixtures capable of replacing sand-argillaceous mixtures whose properties have already been well studied. Unfortunately, the majority of them form a mold in the course of the hardening of a bonding agent, which requires creating a complex system for the regeneration of the used sand. In this connection, we investigated a waterless molding mixture with the use of organobentonite as the binder, which does not require any changes in the technological process of green-sand molding. The influence of the amount and composition of the solvent on the properties of waterless mixtures is estimated.     

Application of elastic mid-infrared light scattering to the investigation of internal gettering in Czochralski-grown silicon

The influence of the internal gettering process on the large-scale defects in Czochralski-grown boron-doped single-crystal silicon is investigated by low-angle mid-infrared light scattering. The large-scale defects in the as-grown material and crystals subjected to the internal gettering procedure are classified. The applicability of low-angle light scattering in laboratory investigations and in the industrial inspection of the operations in an internal gettering production cycle is demonstrated. Fiz. Tekh. Poluprovodn. 31, 1158–1163 (October 1997)     

795 nm and 1064 nm dual pump thulium-doped tellurite fibre for S-band amplification

Gain measurement in thulium-doped tellurite fibre is demonstrated with a maximum internal gain of 7 dB at 1480 nm. An improvement in gain by a factor of 2 is achieved using a 795 nm and 1064 nm dual pump scheme. Gain in tellurite fibres extends to longer wavelength than in fluorides, showing improved overlap with the C-band EDFA.     

Structure and mechanical properties of a nonmagnetic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification

The structure and properties of an austenitic high-nitrogen corrosion-resistant 05Kh22AG15N8M2F cast steel produced by high-gradient directional solidification (HGDS) and equiaxed-grain solidification (ES) have been studied and compared. In contrast to ES, HGDS allows one to substantially decrease the degree of dendritic segregation of alloying elements, to eliminate porosity, and to increase the strength and plasticity of the steel.     

Analysis of global and local extrema of regularizing functionals in the problem of the reconstruction of images observed through randomly inhomogeneous media

An approach to the reconstruction problem of undistorted images of objects observed through randomly inhomogeneous media is considered. The approach is based on the solution to the integral equation of the first kind (convolution equation) with an unknown kernel and inaccurately defined right-hand side. It is demonstrated that the procedure for the construction of an inverse operator needed for the solution is determined by the minimization of the nonlinear regularizing multiextremum functional, which takes into account the a priori data regarding the positive intensity distribution in the image of an object. The analysis of the structure of the multiextremum functional is presented. The estimates of the reconstructed images that correspond to the global and local extrema are studied. The results of a numerical experiment on the reconstruction of the optical image of an object observed through the turbulent atmosphere are presented.     

Pulse discharge characteristics of an insulating system typical of a nonlinear overvoltage limiter

Results of the studies of the discharge characteristics of insulating systems of high-voltage overvoltage limiters during lightning pulses are presented. For certain dimensions of the screen system of the overvoltage limiters, it is shown that the electric strength of their external insulation may be determined by the discharge voltages of the gap between the screen and the stack of voltage-dependent resistors. A semi-empiric technique for calculating the discharge voltages of the insulating systems of overvoltage limiters during lightning surge is developed.