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15 results on '"Lapina, Polina A."'

10. Features of Functioning of the Central Nervous System of the Residents of Moscow and Moscow Region

Author

Belyaev Dmitry, Fedorova Elena, Lapina Polina, and Kazakov Alexander

Subjects
medicine.anatomical_structure, Geography, General Arts and Humanities, Central nervous system, medicine, General Social Sciences, General Economics, Econometrics and Finance, Neuroscience
Abstract

The study focuses on the lability and adaptability of the central nervous system of residents of Moscow and Moscow region aged 65 and older. All examinees regularly practised various types of physical activity, such as Nordic walking, cycling, Qigong gymnastics, etc. The functional state of the central nervous system of the examinees was studied using the Psychophysiologist hardware-software system by determining simple visual-motor reaction (SVMR), complex visual-motor reaction (CVMR), reaction to a moving object (RMO). Based on the analysis of speed and stability of sensorimotor reactions in response to light stimuli and moving object we made an express-evaluation of the level of functional state of the central nervous system, sensorimotor reactions, quality of activity, balance of inhibition and excitation processes. As a result of the study, the optimal level of CNS functioning was registered in most of the examinees. Activation of the central nervous system in the majority of the examinees is at an average level, the average level of operative efficiency is noted. The results of the study indicate a shift in the balance of nervous processes in the examinees towards inhibition.

Published
2021

11. Dynamics of thermoelastic frictional wear of a coating with piezoelectric interlayer

Author

Lapina Polina A., Mitrin Boris I., Kuznetsova Tatyana A., and Lapitskaya Vasilina A.

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

To study dynamics of a coating wear, this paper deals with an uncoupled thermoelastic contact problem on sliding of a rigid punch over the surface of a thermoelastic coating bonded to an electroelastic interlayer, which itself is bonded to an undeformable substrate. Friction, frictional heating and coating wear on the contact is taken into account. The problem solution was constructed by the Laplace integral transform method and was obtained in the form of the Laplace convolutions. Based on the obtained expressions it is possible to develop technique for monitoring of a coating wear on a sliding contact through values of electric current arising in the piezoelectric interlayer.

Published
2018
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15. Wear of Functionally Graded Coatings under Frictional Heating Conditions.

Author

Zelentsov, Vladimir B., Lapina, Polina A., and Mitrin, Boris I.

Subjects
*FUNCTIONALLY gradient materials, *ABRASIVE machining, *THERMOELASTICITY, *SURFACE coatings, *INTEGRAL transforms, *DEBYE temperatures
Abstract

Multilayered and functionally graded coatings are extensively used for protection against wear of the working surfaces of mechanisms and machines subjected to sliding contact. The paper considers the problem of wear of a strip made of a functionally graded material, taking into account the heating of the sliding contact from friction. Wear is modeled by a moving strip along the surface of a hard abrasive in the form of a half-plane. With the help of the integral Laplace transform with respect to time, the solutions are constructed as convolutions from the law of the introduction of an abrasive into the strip and the original in the form of a contour integral of the inverse Laplace transform. The study of the integrands of contour quadratures in the complex plane allowed determination of the regions of stable solutions to the problem. Unstable solutions of the problem lead to the concept of thermoelastic instability of the contact with friction and formed regions of unstable solutions. The solutions obtained made it possible to determine a formula for the coefficient of functionally graded inhomogeneity of the coating material and to study its effect on the occurrence of thermoelastic instability of the contact taking friction into account, as well as on its main characteristics: temperature, displacement, stress and wear of the functionally graded material of the coating. The effects of the abrasive speed, contact stresses and temperature on wear of the coating with the functionally graded inhomogeneity of the material by the depth were investigated. [ABSTRACT FROM AUTHOR]

Published
2022
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