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.     

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.     

SAW Microsensor Brain Implant for Prediction and Monitoring of Seizures

An implantable surface acoustic wave (SAW) microsensor has been developed for early detection and monitoring of seizures based on local temperature changes in the brain's epileptogenic zones that occur prior to and during an epileptic event. Three SAW sensors were designed and fabricated: a 172 MHz filter, a 434 MHz filter, and a 434 MHz delay line. Their temperature sensitivities were tested by measuring the phase change between the input and output waveforms as a function of temperature. We achieved a phase sensitivity of 144 phase degrees per degC and a minimum detectable temperature of 5 mK for the 434-MHz, 10.2-mus delay line. Based on the sensitivity tests, a prototype 434 MHz SAW sensor was fabricated to a size of 11times1times1.1 mm, which is commensurate with existing brain implantable probes. Because of possible damping of the surface waves by the surrounding tissue or fluid, a glass housing with dry air was built on the top of the SAW substrate. Test and reference sensors were used in the prototype system to minimize the effect of source instabilities and to amplify the temperature effect. The phase change between the output waveforms of the sensors was measured with phase detector electronics after they were converted to lower (10.7 MHz) frequencies by standard mixers. The complete prototype sensor was tested in a saline water bath and found to detect as low as 3 mK changes of temperature caused by the addition of hot water.     

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.     

Influence of Au and Pt on the concentration profile of Mn in Si

The influence of diffusion of gold and platinum from the layer deposited on the silicon surface on the concentration profile of ⁵⁴Mn in the bulk is investigated using the radiochemical technique. The data obtained indicate that the manganese concentration in the bulk of silicon is reduced due to annealing of the samples Si〈⁵⁴Mn〉 with the gold or platinum layer on the surface.     

Optimizing the diamond machining of ceramics on the basis of systemic analysis using neural networks

A generalized algorithm is presented for estimating the efficiency of diamond machining of ceramics. The algorithm is based on systematic analysis of the influence of the technological media and the conditions and employs up-to-date computational techniques.