Volumetric out-of-furnace heat treatment of 3600-M3 decomposers

Specifications require that all the welds in 12-m-diam. decomposers with a capacity of 3600 m³ be subjected to high-temperature tempering before going into service in order to alleviate the stresses from the welding operation. Specialists at the organizations VNIIPTkhimnefteapparatury and VNIImontazhspetsstroi have proposed out-of-furnace volumetric (complete) of the assembled decomposer with the use of special heaters. The use of this heating method has shortened assembly operations while providing the welds with a highquality heat treatment and reducing the stresses overall (including welding stresses, stresses from assembly of the decomposer, etc.) The technology ensures uniform heating of the housing of the decomposer and provides for close control over the process. The experience gained in heat-treating decomposers can also be used in the construction of other containers that come into contact with corrosive media. __________ Translated from Metallurg, No. 3, pp. 61–64, March, 2006.     

Low-temperature diffusion of implanted sodium in silicon

Technical Physics Letters - We have studied the low-temperature diffusion of sodium atoms implanted (at primary ion energy E = 300 keV to total doses within Φ = 5 × 1014–3 ×...     

Development of a rational roll pass design for a rolling mill using performance criteria

A new technique is developed to analyze the roll pass design of a section rolling mill. Metal forming nonuniformity and efficiency coefficients, which determine the degree of working of a metal microstructure in rolling of section bars, are used as performance criteria. The system of roll passes intended for the production of a round bar 28 mm in diameter is used as an example to analyze possible deformation schemes and the advantages and disadvantages of each scheme.     

Centering of continuous-cast billet prior to piercing at OAO Severskii Trubnyi Zavod

Attention focuses on how the centering of continuous-cast billet prior to piercing affects the geometry of thin- and thick-walled sleeves at OAO Severskii Trubnyi Zavod. The influence of the depth and shape of the rear centering socket on the variation in wall thickness at the rear of the sleeve is studied.     

Toward an analysis of the evolution of normal axially symmetrical forms of anisotropic circular plates and cylindrical rotational shells

An expanded formulation of problems of analysis is given which includes: linear ordinary differential equation of state; specification of the loading trajectory; classification of the modulation types; classification of areas of modulation types and their boundaries; ratios of the relation of the “stiffness factors” of linear ordinary differential equations and structural parameters—“coefficients of Bessel additives”; classification of critical lines—isoparametric and points; linear boundary conditions of the differential type; and determinant-boundary equations.     

Minimal-dot plot: “Old tale in new skin” about sequence comparison

The authors propose a simple version of the dot-plot scheme to be used in the case when the distances between sequence elements may take more than two values. The method is applicable, in particular, to the case of the sequences of large-length windows when the sets of distance values are continuous. The proposed technique is simple to implement and the results can produce readable maps for further analysis. To illustrate its potentialities, the method has been applied to the comparison of genomic sequences. The asymmetry in the number of direct and reverse tracks for the Homo sapience genome has been discovered.     

Development,construction, and use of pneumometric tubes for measurement of steam flow in the steam lines of PVG-1000 at NPP

A system for the direct measurement of steam flow in steam lines after a steam generator, which utilizes a special design of pneumometric tubes and a computing unit that accounts for variation in steam pressure, has been developed to improve the quality of water-level regulation in the steam generators of VVéR-1000 power-generating units in the stationary and transitional modes. The advantage of the pneumometric tubes consists in their structural simplicity, high erosion resistance, and absence of irrevocable losses during measurement of steam flow. A similar measurement system is used at foreign NPP. The measurement system in question has been placed in experimental service at the No. 3 unit of the Balakovo NPP, and has demonstrated its worthiness. This measurement system can also be used to determine steam flow in the steam lines of NPP units with VVéR-1000 and VVéR-440 reactors, and PBMK-1000 power-generating units. __________ Translated from élektricheskie Stantsii, No. 3, March 2007, pp. 23–26.     

GaAs–AlGaAs heterostructure thyristors with completely optical transfer of emitter current

Several variants of thyristors based on GaAs-AlGaAs heterostructures with optical transfer of the emitter current are considered. The possibility that thyristors with fully optical transfer of the emitter current can be, in principle, created is demonstrated by means of the results of a study of n-p-n and p-n-p optoelectronic transistors in which the emitter current is converted into light, this light, in turn, being converted into a collector current. Structures of optoelectronic switches of this kind are presented. A switch comprising three constituent transistors has been suggested and fabricated taking into account specific features of the technique for growth of undoped GaAs layers and fabrication of high-voltage p ⁰-n ⁰ junctions with back-ground impurities from these layers, which makes the turn-on delay cardinally shorter and raises the working frequency.