Design aspects of planar and conventional SMPS transformer: a cost benefit analysis

The intent of this paper is to design a high-frequency transformer that is to be incorporated into the DC/DC pulsewidth-modulated switch-mode power supplies by two different technical approaches: a conventional wound-coil magnetic using copper wires, and a planar magnetic with layered copper tracks on laminated printed circuit board. Comparisons will be made between the two approaches in terms of profile: mounting height and surface area, and performance: power losses and efficiency. Other indicators like temperature rise and leakage inductance that causes electromagnetic interference, and cost, materials, and process fluency are also to be looked into. A sandwiched configuration for primary and secondary windings is proposed for the planar type. Issues arising and typical phenomena encountered will be discussed in detail. Primarily, the dominating factor in performance, cost effectiveness, or circuit compactness that restrains the choice of a particular type is to be evaluated.     

Measurement of sulfur content in pulps of the Novoyavorovo ore refinery by a neutron radiation method

We describe an apparatus and method for measurement of the sulfur concentration in the pulp stream under refinery conditions using neutron radiation analysis. We present the block diagram for the apparatus and the results of testing of the apparatus at the Novoyavorovo ore refinery.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 60–61, February, 1995.     

Effect of Annealing in an Active Boron-Containing Medium on Surface Hardening of Nitrided Titanium

We studied the effect of the structural and phase state of surface layers of nitrided VT1-0 titanium on its surface hardening after additional saturation in an active boron-containing atmosphere (900°C, 5 h, 0.1 MPa Ar, a mixture of boron carbide and borax). Additional treatment almost doubles the surface microhardness of the specimens. Surface hardening is a result of both the formation of borides and carbides and the introduction of additional elements into the lattice of titanium nitrides. We established that the formation of a nonstoichiometric nitride with a deficiency of the nonmetallic component prior to additional treatment enables one to reach the maximum effect of surface hardening.     

Effect of the physical properties of a wall on heat transfer in turbulent natural convection. 2. Analytical study

The experimental heat transfer coefficient is calculated from data on the structure of the turbulent boundary layer and assumptions on heat-transfer mechanism.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 60, No. 5, pp. 730–735, May, 1991.     

Designer's casebook-bridge-controlled duty-cycle oscillator withgrounded capacitor

A circuit that uses the parallel connection of a Schmitt-trigger-type multivibrator and a voltage-controlled current source is proposed. The circuit was developed for use with integrated silicon sensors. The operation of the circuit is described     

Correlation between magnetic properties and the hardness of powder steels

Density and carbon content are studied for their effect on strength (hardness) and magnetic (coercive force, saturation magnetization) properties of powder steels ZhGr1 and ZhGr1D3. It is shown that the hardness of articles made of these steels may be determined indirectly by measuring two magnetic characteristics.Physicotechnical Institute, Russian Academy of Sciences, Izhevsk. Translated from Poroshkovaya Metallurgiya, Nos. 1–2, pp. 67–69, January–February, 1994.     

Hydrogen-assisted cracking

This article reviews a number of case studies involving hydrogen-assisted cracking in steels. Before the case studies are presented, the current state of understanding of hydrogen-assisted cracking is briefly reviewed. At present there are two leading approaches to the development of a mechanism of hydrogen-assisted cracking, one based upon bond weakening, and the other upon strain localization. As the case studies illustrate, hydrogen-assisted cracking can lead to failures in perhaps unexpected circumstances. The need for the wider dissemination of information about hydrogen cracking to design engineers is indicated.     

Crystallization and melting behaviour of poly(butylene terephthalate) in poly(butylene terephthalate)/polyarylate blends

Summary The crystallization and melting behaviour of poly(butylene terephthalate) has been studied in the pure state and in its blends with a polyarylate of bisphenol A and isophthalic/terephthalic acids. Differential scanning calorimetry has been used as experimental technique and the effects of different thermal treatments have been analyzed. Results show the hindrance for the crystallization of poly(butylene terephthalate) imposed by the presence of polyarylate, as well as the existence of multiple melting after isothermal crystallization. Explanations are given for the observed behaviours.     

A Study of the Dust Collection Process in the Production of Refractories

An experimental setup for studying filter-assisted dust collection is described. The role of various factors — hydraulic resistance, filtering velocity, dust concentration, pressure drop, efficiency of recovery — in the performance of filters intended for use in the production of refractory materials is considered. The dust removal method was tested under industrial conditions at the Semilukskii Refractory Plant and can be recommended for wider use in different branches of industry.