Strengthening of threaded connections of titanium and high-temperature nickel-chromium alloys by thermovibration treatment

The article presents results of a study of the strengthening of threaded connections M6 and M8 of alloys ÉI698, VT16, and VTZ-1 by thermovibration treatment to raise their creep resistance. Treatment regimes and empirical formulas for determining the index of strengthening (for the ÉI698 alloy) are discussed. Data on long-term strength of threaded connections in initial and post-treatment states, and on the effect of aging on retention of the strengthening effect, are presented along with some mechanical and fatigue characteristics.Translated from Problemy Prochnosti, No. 9, pp. 98–103, September, 1990.     

Nature of scatter of fracture toughness in static loading

The previously proposed model of unstable fatigue crack growth is used to explain a large (in comparison with other mechanical characteristics) scatter of static fracture toughness for 15Kh2MFA and 15Kh2NMFA steels at temperatures below the tactile-brittle transition temperature. The results show that for the materials for which K_fc ¹ < K_Ic the critical stress intensity factor K_Ic depends on the specific energy of inelastic strain W at the tip of the initial fatigue crack in its formation stage. The value of W is a function of the number of load cycles (in the conditions with a constant range of the stress intensity factor K) as a result of irregular fatigue crack growth. Here K_fc ¹ is the minimum cyclic fracture toughness. A method is proposed of evaluating the minimum fracture toughness of the material in static loading based on inspection of the process of irregular fatigue crack growth in the stage of crack initiation.Translated from Problemy Prochnosti, No. 2, pp. 10–16, February, 1990.     

Classes of conjugate elements of the unitriangular group

The paper examines the classes of conjugate elements of the unitriangular group. It is shown that for sufficiently large n the problem of describing the classes of conjugate elements of the group G includes the problem of unitriangular similarity of pairs of matrices. Effective algorithms are constructed for enumeration of classes of conjugate elements and their elements. Representatives of the classes of conjugate elements of the group G with n9 are obtained by computer.Translated from Kibernetika, No. 1, pp. 40–48, January–February, 1990.     

Filter materials for fine cleaning based on metal fibers

Conclusions Permeable materials based on metallic fibers with porous layers sprayed on by the detonation gas method, in tangential filtering of media with ferromagnetic and abrasive impurities ensure fineness of cleaning 1–2 m with comparatively low hydraulic resistance. The application of a magnetic field to material with sprayed-on layer of magnetic alloy made it possible to increase permeability to ferromagnetic particles by a factor of more than 1.5.Translated from Poroshkovaya Metallurgiya, No. 1(325), pp. 77–80, January, 1990.     

Composition of acid tars from production of oils

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 32–35, February, 1990.     

Waste products from the butane-butylene fraction as raw material for the production of methyl-tert-butyl ether

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 8, pp. 7–8, August, 1990.     

HAR-sEMG: A Dataset for Human Activity Recognition on Lower-Limb sEMG

Knowledge and Information Systems - In the past decade, human activity recognition (HAR) has grown in popularity due to its applications in security and entertainment. As recent years have...     

Feasibility of the indirect determination of blast-induced rock movement based on three new hybrid intelligent models

Engineering with Computers - The indirect and accurate determination of blast-induced rock movement has important significance in the reduction of ore loss and dilution and in the protection of...     

Authority updating: An expert authority evaluation algorithm considering post‐evaluation and power indices in social networks

In group assessment, the focus is on finding high‐authority experts to improve the reliability of assessment results. In this study, we propose an authority updating algorithm while considering the power and judgement reliability of an expert on the basis of social networks and post‐evaluations. A network power index is established and used to reflect the power of an expert while considering social networks. The measurement of the judgement reliability of an expert considers the post‐evaluation of the objects selected by experts, thereby more scientifically reflecting the reliability of experts. The analysis shows the following: although the social‐network structure influences the authority of experts, the influence weakens when the assessment group is a highly or even fully connected group; the network effect may increase the authority of some experts and reduce that of others, and it will weaken as the network connectivity increases; moreover, the judgement reliability and authority of an expert while considering post‐evaluation can encourage him/her to make fair assessments and strive to reduce his/her motivation and cognitive biases.