Analysis of the time reserve influence on the technological cell productivity

Time redundancy, widely used in technical systems, is one of the methods to improve the reliability and efficiency of technical systems. In this paper, the effect of instantly replenishing the time reserve on the productivity of a technical system is considered. Formulas of productivity of a technological cell in cases of random, constant and exponential time reserve are received, numerical results are given

A method for rapid estimation of residual stresses in metal samples produced by additive manufacturing

The mechanical methods for measuring residual stresses typically rely on so-called destructive techniques where some stress components can be determined based on part deflection after material removal (cutting, etching, drilling, etc.). While these methods don't provide a comprehensive representation of residual stresses within the entire part, they can be readily applied in most manufacturing labs. In this study, we propose an efficient method for determining residual stress within additively manufactured cylindrical samples of stainless steel. The method is based on the assumption of a relation between the axial component of residual stress (normal to cross-section) and the cylinder radius. The general form of this relation is proposed based on data from numerical simulations using linear, parabolic or piecewise approximations. The parameters for the proposed relation are defined using equilibrium equations for total force and moment. The proposed method relies on an experiment with a mechanical cut along the cylinder. Consequently, the deflection of the cylinder halves after the cut allows for obtaining the equivalent bending moment

Economic processes in the safety measurement

The monograph covers the theoretical and methodological foundations of the formation of economic security system and the determinants of its development. Special attention is paid to the influence of geoeconomic factors on the country's economic security in the conditions of globalization and the elimination of the negative impact of world crises on the economic security of Ukraine. The monograph provides a thorough analysis of the international policy of ensuring national security in the context of economic and social aspects. The problem of economic security of regions and economic entities is investigated. The monograph is intended for scientists, lecturers, civil servants, specialists, managers of enterprises and financial institutions, teachers, postgraduates, students, as well as a wide range of readers who are studying national economic security problems

Environmental management as a component of Ukraine’s modern economy: Management under the conditions of martial law

The development of environmental management in Ukraine is determined by the urgent need to overcome environmental problems and ensure the environmental safety of society, especially under the conditions of martial law. Today, the domestic economy is three times more resource-intensive than the world economy, the technological base and infrastructure complex of public production are rapidly wearing out, which leads to a decrease in the level of technological and environmental safety. Environmental management is related to the national economy and forms information about the need to use natural resources when promoting effective development. A comprehensive project-targeted approach to the development of new forms of ownership and market economy reflects the interrelationship of all parts of the nature management project. The development of the scientific foundations of nature management is facilitated by the formulation of a general plan for the placement of productive forces. The ecological situation in Ukraine has long been called a crisis. In recent decades, new scientific directions have appeared, the result of which have been new ideas about human, society and nature and their coexistence. One of these directions is environmental management, which today is the ideology of production activity management, as it provides an effective toolkit for solving current problems and preventing the emergence of new production environmental and economic issues

Polaron Trapping and Migration in Iron-Doped Lithium Niobate

International audiencePhotoinduced charge transport in lithium niobate for standard illumination, composition and temperature conditions occurs by means of small polaron hopping either on regular or defective lattice sites. Starting from Marcus-Holstein’s theory for polaron hopping frequency we draw a quantitative picture illustrating two underlying microscopic mechanisms besides experimental observations, namely direct trapping and migration-accelerated polaron trapping transport. Our observations will be referred to the typical outcomes of transient light induced absorption measurements, where the kinetics of a polaron population generated by a laser pulse then decaying towards deep trap sites is measured. Our results help to rationalize the observations beyond simple phenomenological models and may serve as a guide to design the material according to the desired specifications

Semi-Markov model of a technical system with the component-wise instantly replenished time reserve

Time redundancy is one of the methods to increase the reliability and efficiency of technical systems. When it is used, the system is given additional time (a time reserve) for restoring characteristics. In this paper we construct a semi-Markov model of a two-component system with a component-wise instantly replenished time reserve. In this paper we construct a semi-Markov model of a two-component system with a component-wise instantaneous replenishment of the time reserve. For an approximate determination of the stationary characteristics of the reliability of the system, the phase merging scheme algorithm is used

Analysis of the time reserve influence on the technological cell productivity

Time redundancy, widely used in technical systems, is one of the methods to improve the reliability and efficiency of technical systems. In this paper, the effect of instantly replenishing the time reserve on the productivity of a technical system is considered. Formulas of productivity of a technological cell in cases of random, constant and exponential time reserve are received, numerical results are given

Analysis of the time reserve influence on the technological cell productivity

Time redundancy, widely used in technical systems, is one of the methods to improve the reliability and efficiency of technical systems. In this paper, the effect of instantly replenishing the time reserve on the productivity of a technical system is considered. Formulas of productivity of a technological cell in cases of random, constant and exponential time reserve are received, numerical results are given

Hidden Markov Model and States Prediction of an Autonomous Wind-Diesel Complex

The problem of assessing the reliability and analyzing the functioning of an autonomous winddiesel complex, consisting of a wind power plant, working and standby diesel generators, an inverter and a storage battery, is considered. First, a semi-Markov model of an autonomous wind-diesel complex is built, which makes it possible to calculate the stationary and temporal reliability characteristics. Then, on its basis, a hidden Markov model is developed, which is used to solve the problems of predicting and evaluating its characteristics, taking into account the given parameters and the signal vector. The results of the study are obtained in a general form and are invariant with respect to the laws of distribution of random variables describing the elements of an autonomous wind-diesel complex. They allow you to simulate the functioning of the system under various distribution laws, based on statistical data, without modifying the model itself

Anisotropy of Mechanical Properties and Residual Stress in Additively Manufactured 316L Specimens

In the presented study, LPBF 316L stainless steel tensile specimens were manufactured in three different orientations for the analysis of anisotropy. The first set of specimens was built vertically on the build platform, and two other sets were oriented horizontally perpendicular to each other. Tensile test results show that mean Young’s modulus of vertically built specimens is significantly less then horizontal ones (158.7 GPa versus 198 GPa), as well as yield strength and elongation. A role of residual stress in a deviation of tensile loading diagrams is investigated as a possible explanation. Simulation of the build process on the basis of ABAQUS FEA software was used to predict residual stress in 316L cylindrical specimens. Virtual tensile test results show that residual stress affects the initial stage of the loading curve with a tendency to reduce apparent Young’s modulus, measured according to standard mechanical test methods