Studying the thermophysical characteristics of nonmetallic coatings

A method is described for experimental determination of the thermophysical characteristics of nonmetallic coatings. Experimental data for one such coating is presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 6, pp. 971–976, June, 1982.     

Production of nanopowders of yttrium-aluminum garnet by the Pechini method

Results are presented from the synthesis of nanopowders of yttrium-aluminum garnet by the Pechini method. It is established that the Pechini method is a promising technology for producing optically transparent ceramics.     

Technique and Calculation Results of Currents and Voltages in the Circuits of the Measuring Element of the Protection Device of the Transmission Line Based on the Control of Transient Processes

The specifics of generation of the signals of current and voltage in the circuits of a directional element of wave relay protection during short circuit (SC) in overhead power transmission lines are considered. The computing method of transient processes in the protection circuits, including frequency filters, that attenuate the parameters of currents and voltages of the mode taking into account the higher harmonic components and probable deviations of the frequency of transmission line from the rated value is presented. It is revealed that it is advisable to implement the measuring circuits of the directional elements of wave relay protection with the three-section filter attenuating the frequencies from 45 to 55 Hz and the low pass filter with cutoff frequency that does not exceed 1 kHz.     

Seismic, Hydroacoustic, and Acoustic Action of Underwater Explosions

Results of a fullscale study of hydroacoustic, seismic, and acoustic effects of an underwater explosion of charges of a chemical high explosive are described. The study had a comprehensive character and included video filming of surface phenomena at the explosion epicenter, registration of hydroacoustic waves in water, seismic waves on the ground, and acoustic waves in air at distances of 0.08–30 km from the explosion epicenter. Parameters of these waves and the character of their decay with distance were obtained, and the wave spectra were analyzed. It is shown that the main specific feature of the wave shapes of hydroacoustic, seismic, and acoustic signals is caused by oscillations of the cavity filled by detonation products, which can be used to identify underwater explosions.     

Monitoring of the current-distribution uniformity in bipolar transistors from the dependence of internal-feedback factor on collector voltage

On the basis of the two-section model of a high-power bipolar transistor, it is shown that the slope of dependence of the small-signal feedback coefficient on the collector voltage in the presence of defects in the transistor is proportional to the defect size. The setup for the automated monitoring of the current-distribution nonuniformity in the transistor device structure from the indicated dependence with using the combination of linearly increasing and small harmonic variations in the collector voltage is described. The experimental dependences confirming the results of the theoretical analysis are presented.     

Analysis of quality-of-service metrics in IMS networks

A network constructed according to the IMS architecture consists of different modules that sequentially process signaling messages transferred during providing communication services. Delays that occur when processing signaling messages determine the quality of service for subscribers. International recommendations define the quality-of-service metrics, which include not only the mean, but also the 95% quantile. The paper proposes an approach to analyzing the quality-of-service characteristics. It is assumed that IMS-network nodes work as multi-server queues with general service time distribution.     

Periods of stable and unstable ERP topography for target and nontarget visual stimuli

Topographic analysis of event-related potentials (ERPs) has been used for segmentation of brain activity into microstates for a long time. But little is known about dynamics of topographic changes. This work shows that this dynamics is rather complex: ERPs consist of relatively long periods of stable topography (about 50 ms long) and relatively short unstable periods interspersed with them (about 20 ms long). A mathematical algorithm used for estimation of a degree of ERP topography instability is given. It is based on calculation of successive difference between normalized topographical vectors.     

Spatial relations in the semantic SL language and its prototype,universal Dial language

The process of developing a way to describe spatial relations (SR) in the semantic SL language for the knowledge translation problem is described. To do this, a system of notions is introduced—a reference body and reference system (RS) as opposed to the notion of an orientation point used in analyzing the spatial relations of natural languages. The term “orientation” used to characterize types of motion is replaced by the more exact term “dynamics.” On the whole, the two-parametric scheme proposed by other authors is preserved for describing spatial relations. The notions of dynamics and topological zone are used as parameters. Values of parameters and a designation system are developed on the basis of SL principles. To conclude the work, examples of writing spatial relations using the mentioned parameters are given.     

Non-linear strain-displacement equations exactly representing large rigid-body motions. Part III. Analysis of TM shells with constraints

The precise representation of arbitrarily large rigid-body motions in the displacement patterns of curved Timoshenko-Mindlin-type (TM) shell elements has been considered in Part I of the present work. In Part II it has been developed an enhanced mixed finite element formulation that allows using load increments that are much larger than possible with existing geometrically exact displacement-based shell element formulations. In this paper the developed formulation is employed to solve frictionless contact problems for TM shells undergoing finite deformations and interacting with rigid bodies. The contact conditions are incorporated into the assumed stress-strain TM shell formulation by applying a perturbed Lagrangian procedure with the fundamental unknowns consisting of 6 displacements and 11 strains of the bottom and top surfaces of the shell, 11 conjugate stress resultants and the Lagrange multiplier, associated with a nodal contact force, through using the non-conventional technique. The efficiency and accuracy of the proposed finite element formulation are demonstrated by means of several numerical examples.