Error of measurement of coolant temperature in VVÉR-440 reactor

Translated from Atomnaya Énergiya, Vol. 67, No. 5, pp. 358–359, November, 1989.     

Polygonal approximation for image segmentation

A new learning model for real-time, grey-level image segmentation is presented. The model gives excellent results for images with different shapes.     

Transformation-toughening in cemented carbides: Part II. Thermomechanical treatments

WC-(Fe, Ni, C) cemented carbides can be successfully transformation-toughened by careful control of binder composition and taking into consideration the effect of thermal residual stress on the transformation characteristics of the binder. An additional degree of control on the metastability of the binder phase can be achievedvia thermomechanical treatments. These treatments consist of transforming an austenitic binder to martensite by cooling in liquid nitrogen followed by a suitable high temperature heat treatment to reaustenitize it. Thein situ deformation of the binder caused by the large shape and volume changes that accompany its transformation to martensite thus provides the mechanical component of the thermomechanical treatment. Subsequent heat treatments not only reaustenitize the binder but also modify its susceptibility to undergo stress-induced transformation. It is shown that the hardness/fracture toughness behavior of WC-(Fe, Ni, C) cemented carbides can be significantly improved by the application of such treatments. A qualitative explanation for the enhancements in fracture toughness provided by thermomechanical treatments is offered based on a careful examination of the changes in phase constitution of the binder that occur during these treatments. Formerly Manager, Research-Development, Reed Tool Company, Houston, TX.     

Al-Cu-Fe QUASICRYSTALLINE PHASE FORMATION BY MECHANICAL ALLOYING

Al-Cu-Fe alloys were prepared from elemental powders in a high-energy planetary ball mill. A sequence of solid state reactions resulting in quasicrystal (QC) phase formation takes place during heating of the as-milled powder. These reactions were studied by both differential scanning calorimetry and x-ray diffraction methods. Mechanically alloyed powders were consolidated by cold and hot pressing, as well as by explosive compaction. After annealing at sufficiently high temperatures, the consolidated samples are single-phase QC, except the ones consolidated by explosion. The high reactivity of the as-milled alloys causes the appearance of high porosity of the consolidated samples after the annealing.     

Surface acoustic wave gas sensor of the sorption type sensitive to the thermal properties of gases

The basic principles of a new surface acoustic wave (SAW) gas sensor are described. Being essentially a sensor of the sorption type, the proposed device possesses certain features of the thermometric SAW sensors and is not only sensitive to the vapors of volatile substances, but capable of detecting gases by their thermal properties as well. In contrast to the known thermometric SAW sensors, the proposed sensor is characterized by high temperature stability and fast response. A variant of the sensor based on a LiNbO₃ SAW delay line is described and some results of the test for detecting propane-butane mixtures are presented.     

Dependence of the Parameters of an Electronuclear System on the Composition of Mixed Uranium–Plutonium Fuel

Mathematical simulation is used to study the dependence of the parameters of an electronuclear system with uranium–plutonium mixed fuel on the amount of plutonium and ²⁴⁰Pu admixture in the fuel. As an example, a 10–20 kW(t) experimental system built at Dubna on the basis of a synchrocyclotron with 660 MeV protons is examined. A 2% admixture of ²⁴⁰Pu decreases the neutron multiplication factor from 0.95 to 0.9 and decreases the neutron yield and heat released by almost a factor of 2. This decrease can be compensated by increasing the plutonium content in the mixed fuel from 25 to 27%.     

The Scientific Research Seminar on Computer Algebra in 2000–2001

An annual report on meetings of the scientific research seminar on computer algebra is presented.     

New One-Generator Quasi-cyclic Codes over GF(7)

Let [n,k,d] _q codes be linear codes of length n, dimension k, and minimum Hamming distance d over GF(q). In this paper, seventeen new codes are constructed, which improve the known lower bounds on minimum distance.