Special features of the technology of boronizing steel in a calcium chloride melt

A technology for hardening machine parts and tools by boronizing in molten calcium chloride with amorphous-boron powder in electrode salt baths has been developed with the aim of creating a closed cycle of utilizing the raw materials and the washing water. A process of boronizing that includes quenching and tempering of the boronized articles is described. The quenching medium is an ecologically safe and readily available aqueous solution of calcium chloride. The process envisages return of the melt components to the boronizing bath. Boronizing by the suggested method was tested for different classes of steel, namely, structural and tool steels for cold and hot deformation. The wear resistance of the boronized steels was studied. Translated from Metallovedenic i Termicheskaya Obrabotka Metallov, No. 12, pp. 3–7, December, 1999.     

Mechanism of the radiation-protective effect of indralin

Output from the interpositus nucleus can inhibit the inferior olive, probably via the GABA-ergic nucleo-olivary pathway. It has been suggested that the function of this inhibition might be to regulate synaptic plasticity resulting from parallel fibre/climbing fibre interaction in cerebellar Purkinje cells, by providing negative feedback information to the olive. Thus, when a learned response, generated by the interpositus nucleus, reaches a sufficient amplitude, the olive would be inhibited and further learning blocked. This suggestion was tested in a classical conditioning paradigm. Decerebrate ferrets were trained using electrical skin stimulation of the forelimb as the conditioned stimulus (CS) and periorbital stimulation as the unconditioned stimulus (US). Climbing fibre responses evoked in Purkinje cells by the US were recorded as surface field potentials in the part of the c3 zone controlling eyeblink. It was found that the CS did not inhibit the olive at the beginning of training, but when conditioned responses were large, the olive was inhibited by the CS in some animals. After a number of unpaired CS presentations, which caused extinction of the conditioned response, the inhibition disappeared. The size of individual conditioned responses correlated negatively with the size of the climbing fibre responses evoked by the US. Climbing fibre responses evoked by direct stimulation of the olive were also inhibited. It was concluded that cerebellar output during performance of a conditioned response inhibits the inferior olive. The results thus support the hypothesis of a cerebellar locus of conditioning and are consistent with the proposed role of cerebello-olivary inhibition.     

Tamping a rock bed through oriented fluid rupture cracks

Kuznetsk Polytechnical Institute, Kemorovo. Institute of Mining, Siberian Department, USSR Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 110–114, September–October, 1989.     

On the Convergence of Fitting Algorithms in Computer Vision

We investigate several numerical schemes for estimating parameters in computer vision problems: HEIV, FNS, renormalization method, and others. We prove mathematically that these algorithms converge rapidly, provided the noise is small. In fact, in just 1-2 iterations they achieve maximum possible statistical accuracy. Our results are supported by a numerical experiment. We also discuss the performance of these algorithms when the noise increases and/or outliers are present. Nikolai Chernov PhD in mathematics from Moscow University in 1984. Researcher in JINR (Dubna, Russia) in 1984–91. Professor of Mathematics at University of Alabama at Birmingham, USA, since 1994.     

Effect of Doping on Helium Behavior and Bubble Structure Development in Nickel and Vanadium Alloys

Transmission electron microscopy and thermal desorption spectrometry are used to study the behavior of ion-implanted helium and formation of a gas bubble structure in fcc and bcc metals as a function of the concentration of the alloying elements (aluminum in nickel and titanium in vanadium). It is shown that during post-radiation annealing of room-temperature irradiated samples alloying in both types of alloys substantially decreases the size and increases the density of the bubbles formed. In nickel–aluminum alloys, with post-radiation uniform heating, the thermal desorption peaks shift to high temperature with increasing aluminum content and, conversely, in vanadium–titanium alloys a shift to low temperature with increasing titanium concentration occurs, though the effective gas release activation energy increases in both alloys with increasing concentration of the alloying element. The data obtained are discussed from the standpoint of the influence of doping on the mechanisms of growth and migration of bubbles.