Unsteady effects and heat-transfer when starting up power plant

The results of experimental study of unsteady effects on local heat transfer coefficients caused by abruptly increasing of the gas flow temperature in the inlet section of a cylindrical channel are presented.     

Robust weighted likelihood estimation of exponential parameters

The problem of estimating the parameter of an exponential distribution when a proportion of the observations are outliers is quite important to reliability applications. The method of weighted likelihood is applied to this problem, and a robust estimator of the exponential parameter is proposed. Interestingly, the proposed estimator is an /spl alpha/-trimmed mean type estimator. The large-sample robustness properties of the new estimator are examined. Further, a Monte Carlo simulation study is conducted showing that the proposed estimator is, under a wide range of contaminated exponential models, more efficient than the usual maximum likelihood estimator in the sense of having a smaller risk, a measure combining bias & variability. An application of the method to a data set on the failure times of throttles is presented.     

Production of Asphalt from Activated Crude Oil Residues

Preparation is one method of increasing the efficiency of crude oil feedstock refining processes. In this stage, the feedstock can be activated by regulating the balance of intermolecular interaction forces within a crude oil disperse system by different methods: external fields (electric, magnetic); mechanical; using different kinds of additives, primarily those with surface–active properties.     

Vanadium species in new catalysts for the selective oxidation of methane to formaldehyde: Activation of the catalytic sites

New vanadium oxide supported on mesoporous silica catalysts for the oxidation of methane to formaldehyde were investigated by infrared and Raman spectroscopies to identify and characterize the molecular structure of the most active and selective catalytic sites. In situ and operando experiments have been conducted in order to understand the redox and hydroxylation/dehydroxylation processes of the vanadium species. (SiO)₂VO(OH) species were identified in these catalysts in reaction conditions and shown to undergo a deprotonation at 580 °C under vacuum, leading to a site giving a photoluminescence band at 550 nm attributed to reverse radiative decay from the excited triplet state:

(V⁴⁺–O⁻)^*  (V⁵⁺O²⁻). An activation mechanism of vanadium monomeric species with electrophilic oxygen species is proposed.     

Urgent Problems of Creation and Commercial Use of Corrosion-Resistant Ferritic Steels with Special Physical Properties

Metal Science and Heat Treatment -     

Molecular design and characterization of catalysts for NO x selective reduction by hydrocarbons in the oxygen excess based upon ultramicroporous zirconia pillared clays

Approaches to design of zirconia pillared clays via control of the properties of pillaring species in solutions were elaborated. Structural features of pillars and Pt + Cu active components fixed at these nanoparticles were shown to determine catalytic properties of pillared clays in NO_x selective reduction by hydrocarbons in the oxygen excess.     

Morphological and structural features of polyacrylonitrile fibres spun by the dry-wet method

Conclusions -- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.-- A considerable difference in crystalline structure of fibres from binary and ternary copolymers which have been spun into a dimethyl sulfoxide—water bath has been shown.-- Fibres from the binary or ternary copolymer which have been spun into a precipitation bath having a large dimethyl sulfoxide content in water are characterized by a lower degree of swelling.-- Shrinkage of fibres from the binary copolymer in the temperature range 200–220°C is twice as small as the shrinkage of fibres from the ternary copolymer.Deceased.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 19–22, May–June, 1991.     

A new carbon structure in annealed film coatings of the carbon–lead system

Carbon–lead solid solutions coexisting with amorphous carbon have been obtained for the first time in a film coating deposited by ion-plasma sputtering. During subsequent vacuum annealing of carbon–lead films containing more than 68.5 at % Pb, this element almost completely evaporates to leave an amorphous carbon coating on a substrate. During annealing at 1100°C, this amorphous carbon crystallizes into a new hexagonal lattice with unit cell parameters a = 0.7603 nm and c = 0.8168 nm. Characteristic X-ray diffraction data for the identification of this phase are determined.

     

Preparation of bismuth nanoparticles in opal matrices through reduction of bismuth compounds with supercritical isopropanol

Bismuth nanoparticles have been produced in pores of opal matrices by reducing bismuth salts and oxide compounds with supercritical isopropanol. According to transmission electron microscopy data, the diameter of the SiO₂ spheres in the opal matrices is about 260 nm, and that of the bismuth nanoparticles does not exceed 80 nm.     

New Mo3Pb phase with a15 structure formed in solid solutions of film molybdenum-lead system

Ion-plasma sputtering and codeposition of Mo and Pb ultrafine particles have been used for the first time to prepare solid solutions that are alloys over the whole composition range of the binary system, which were obtained in the form of coatings; this confirms the thermal-fluctuation melting and coalescence of small particles. When coatings are formed by molybdenum and lead nanolayers less than 1 nm thick, the mutual dissolution of the components with the formation of solid solutions in each other takes place; in this case, beginning from a concentration of ～25 at % Pb in the alloy, lead atoms give their crystal symmetry for the formed lattice. A new phase was found that was prepared directly in the course formation; it was identified as the Mo₃Pb compound with the A15 body-centered cubic structure. X-ray diffraction data for the identification of the phases were determined. The upper temperature limit of the existence of the Mo₃Pb compound has been found and the unit cell whose volume is 0.1290 nm³ has been constructed.