Eddy-current testing of mechanical characteristics of pressure vessel metals at high frequencies

The dependence of the changes in specific electric conductivity on mechanical stresses in nonmagnetic metals was investigated by the eddy-current method. For this purpose, we used an eddy-current transducer with a frequency of 400 MHz, which allows one to perform local tests of the surface layers of materials. We established that the specific electric conductivity of nonmagnetic metals of pressure vessels linearly depends on equivalent stresses. We also suggest an approach to the prediction of limiting states of pressure vessels on the basis of the results of eddy-current tests.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 2, pp. 104–108, March–April, 1994.     

Analysis of local regions near interfaces in nanostructured multicomponent (Ti-Zr-Hf-V-Nb)N coatings produced by the cathodic-arc-vapor-deposition from an arc of an evaporating cathode

Multicomponent nanostructured (Ti-Zr-Hf-V-Nb)N coatings produced by the cathodic-arc-vapor-deposition method have been studied using several complementary methods of elemental and structural analysis, such as those based on the use of slow positron beam (SPB); proton microbeam (μ-PIXE); electron micro- and nanobeam (EDS and SEM analysis); and X-ray diffraction phase analysis (XRD), including the a-sin²? method of measuring the stress-strain state (X-ray tensometry). The elemental composition, microstructure, residual stresses in nanograins, and in-depth and surface distributions of defects and atoms, as well as the phase composition, stress-strain state, and texture of the coatings have been studied in a 3D representation. It has been found that creating a state of elastic stress-strain compression in the coating can significantly enhance its resistance to oxidation upon annealing. A redistribution of elements and defects (their aligning and segregation) due to diffusion and termination of spinodal segregation has been revealed near interfaces, around grains and subgrains, which occurred without a significant change in the average size of nanograins.     

Determining the Accuracy for Fuzzy Logic Technology Foresight Model

A method for checking the accuracy of prognostic models in the absence of experimental data for comparing the modeling results is presented. The developed neural network determines a technology class, which is compared with the results obtained using the fuzzy logic model. The model accuracy is determined by computing the root-mean-square error of the modeling and the correlation between the results obtained using the fuzzy logic model and the neural network.