Вимірювальна техніка та метрологія. – 2021. – Випуск 82, №3

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Measuring Equipment and Metrology : scientific journal. – Lviv : Lviv Politechnic Publishing House, 2021. – Volume 82, № 3. – 52 р.


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Now showing 1 - 6 of 6
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    Modeling a network of unmanned aerial vehicles
    (Lviv Politechnic Publishing House, 2021) Mykyichuk Mykola; Zihanshyn Nataliya
    The research concerns the methods of UAV group control in networks with duplex communication between nodes built on the “client-server” architecture. Such systems belong to self-organized networks with variable topology. It is important to study the allowable parameters of deviation from the task in the management of a group of UAVs and analysis of the network topology for the group flighting. The network was optimized according to the Ant Colony algorithm ACO. The application of different types of algorithms prevents routing problems in networks, such as ANTMANET, AntNet, ACODV and others. Methods of coordination of group joint actions are considered. A method is proposed by which the optimal number of UAVs operated by one operator can be determined and the traffic intensity of the communication channel is calculated, as well as the bandwidth and packet transmission delay are estimated.
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    Analysis of calorimetric method of measurement of natural gas calorific value
    (Lviv Politechnic Publishing House, 2021) Motalo Andriy; Motalo Vasyl
    The article considers the current methods of measuring the calorific value of natural gas which are valid in the up to-date gasometry. The procedure for measuring the gross and net volume-basis specific calorific value of natural gas by the calorimetric method is analyzed. It is shown that to increase the accuracy and validity of measurement results, the experiment to determine the values of gross and net volume-basis specific calorific should be performed for at least 5 samples of the investigated gas. A methodology for estimating the accuracy of measuring the gross and net volume-basis specific calorific values of natural gas by the calorimetric method by finding estimates of the uncertainty of the obtained measurement results taking into account both random and systematic influencing factors are developed. The uncertainty budgets for measuring the gross and net volume basis-specific calorific values of natural gas have been developed for the practical implementation of the methodology. The results of experimental studies of samples of one of the natural gas fields are given and the objective values of the gross and net volume basis specific calorific with estimates of extended uncertainty are obtained.
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    Validation and verification of measurement methods in clinical diagnosis
    (Lviv Politechnic Publishing House, 2021) Sydorko Ihor; Baitsar Roman; Plakhtiy Oksana
    The article investigates and analyzes the validation and verification of measurement methods in the clinical diagnostic laboratory. The content and features of validation and verification are revealed. Measurement methods are considered in detail. Each direction of validation and verification of measurement methods is analyzed. The difference between validation and verification is substantiated. Measuring systems are increasingly used in the laboratories of the clinical sector. This means that the responsibility for validation lies mainly with the manufacturer. The laboratory may operate a validated methodology, which, for example, is published as a standard, or purchase a ready-made measuring system from a manufacturer for a specific application. In both cases, the main validation operate has already been done, but the laboratory must still confirm its ability to apply the method.
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    Two-color compensative thermometry with corrected adjustment using nonlinearity equation of emissivity spectral distribution
    (Lviv Politechnic Publishing House, 2021) Zhukov Leonid; Petrenko Dmytro
    The article is directed on metrological characteristics increase and extension of the optical thermometry field of use, including two-color compensative thermometry with a priori averaged adjustment. The investigations have been performed for the tungsten. This metal studied in thermometry and metal optics has tabulated quantitative estimations of emissivity which are similar to the most widespread in metallurgy iron-carbon alloys. To increase the reliability and extend the field of use of obtained results, approximated and linearized spectral distributions of tungsten, as well as their mirror representations with decreasing and increasing, convex, linear, and concave distributions of emissivity have been researched. The influence of qualitative and quantitative characteristics of the spectral distributions of emissivity on their nonlinearity coefficient has been studied. The equation of nonlinearity has been obtained. This equation connects the nonlinearity coefficient at the middle wave with the emissivity value at one of the boundary waves through the measured one-color radiation temperatures at 3 operating waves. With a priori knew quantitative estimates of the nonlinearity coefficient at the middle wave and measured one color radiation temperatures, the obtained equation can be used for the calculation of emissivity values at the boundary waves. For example, in the linear spectral distributions of emissivity, the nonlinearity coefficient is equal to 0. The number of solutions for linear distributions of emissivity varies from 1 to 2, and for nonlinear – from 1 to 3. The influence of measurement errors of one-color radiation temperatures at operating waves on the errors of emissivity determination by nonlinearity equation is established. The metrological advantages of two-color compensative thermometry using the emissivity values, corrected by the nonlinearity equation, are proved. It was found, that at the nonselective distribution of measurement errors of one-color radiation temperatures, measurement errors of the object temperature for two-color compensative, spectral ratio, and energy thermometry are insignificant for technical measurements. Under conditions of selective distribution of measurement errors of one-color radiation temperatures, these errors respectively are 0.04 – 0.25 %; 1.66 – 9.30 %; 0.18 – 0.34 %. For nonlinear emissivity spectral distributions, real for tungsten and iron-carbon alloys, the methodical component due to the nonlinearity doesn’t exceed 0.48 %, which is also acceptable for technical measurements. The method has been developed for practically acceptable conditions of primary yrometric information obtaining.
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    Calibration of measuring channels of non-dismantling cyber-physical systems
    (Lviv Politechnic Publishing House, 2021) Stadnyk Bohdan; Yatsuk Vasyl; Mykyichuk Mykola; Yatsyshyn Svyatoslav; Fröhlich Tomas; Mastylo Rostyslav
    The analysis of the concept of Open-Science Space is carried out. The existence of ways to achieve reproducibility and traceability of research results performed by a group of worldwide situated Cyber-physical system operators/supervisors is shown. Ways to ensure the efficient operation of Cyber-physical systems as complex technological non demountable objects with high requirements for metrological characteristics have been studied. To develop the scattered cyber physical systems, the portable stable-in-time code-controlled measures of physical quantities have been studied. They have to be metrologically confirmed in the laboratory before the delivery to the site of the measuring subsystem for its calibration.
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    Study of thermometric material Er1-xScxNiSb. II. Experimental results
    (Lviv Politechnic Publishing House, 2021) Krayovskyy Volodymyr; Pashkevych Volodymyr; Horpenuk Andriy; Romaka Volodymyr; Stadnyk Yuriy; Romaka Lyubov; Horyn Andriy
    The results of a comprehensive study of the crystal and electronic structures, kinetic and energetic performances of the semiconductor thermometric material Er1-xScxNiSb (x = 0 – 0.1) are presented. Microprobe analysis of the concentration of atoms on the surface of Er1-xScxNiSb samples established their correspondence to the initial compositions of the charge, and the diffractograms of the samples are indexed in the structural type of MgAgAs. Because the atomic radius Sc (rSc = 0.164 nm) is smaller than that of Er (rEr = 0.176 nm), it is logical to reduce the values of the unit cell's period a(x) Er1-xScxNiSb, which correlate with the results of mathematical modeling. The temperature dependences of the resistivity ln(ρ(1/T)) contain high- and low-temperature activation regions, which are specific for semiconductors and indicate the location of the Fermi level in the bandgap, and positive values of the thermopower coefficient a (x, T) specify its position – near the valence band . This result does not agree with the results of modeling the electronic structure for its ordered version. The presence of a low-temperature activation region on the ln(ρ(1/T)) p-ErNiSb dependence with an activation energy = 0.4 meV indicates the compensation of the sample provided by acceptors and donors of unknown origin. A decrease in the values of the resistivity ρ(x, T) and the thermopower coefficient a(x, T) points to an increase in the concentration of holes in p-Er1-xScxNiSb in the area of concentrations x = 0 – 0.03. This is possible in a p-type semiconductor only by increasing the concentration of the main current carriers, which are holes. The fact of increasing the concentration of acceptors in Er1-xScxNiSb at insignificant concentrations of impurity atoms is also indicated by the nature of the change in the values of the activation energy of holes from the Fermi level to the valence band . Consequently, if in p-ErNiSb the Fermi level was at a distance of 45.4 meV from the level of the valence band , then at the concentration Er1-xScxNiSb, x = 0.01, the Fermi level shifted towards the valence band and was located at a distance of 13.6. Since the Fermi level reflects the ratio of ionized acceptors and donors in the semiconductor, its movement by x = 0.01 to the valence band is possible either with an increase in the number of acceptors or a rapid decrease in the concentration of ionized donors. At even higher concentrations of Sc impurity in p-Er1-xScxNiSb, x ≥ 0.03, low-temperature activation sites appear on the ln(ρ(1/T)) dependences, which is a sign of compensation and evidence of the simultaneous generation of acceptor and donor structural defects in the crystal nature. This is also indicated by the change in the position of the Fermi level in the bandgap of the semiconductor Er1-xScxNiSb, which is almost linearly removed from the level of the valence band : (x = 0.05) = 58.6 meV and (x = 0.10) = 88.1 meV. Such a movement of the Fermi level during doping of a p-type semiconductor is possible only if donors of unknown origin are generated. For a p-type semiconductor, this is possible only if the concentration of the main current carriers, which are free holes, is reduced, and donors are generated that compensate for the acceptor states. This conclusion is also confirmed by the behavior of the thermopower coefficient a(x, T) at concentrations x ≥ 0.03. The results of structural, kinetic, and energy studies of the thermometric material Er1-xScxNiSb allow us to speak about a complex mechanism of simultaneous generation of structural defects of acceptor and donor nature. However, the obtained array of experimental information does not allow us to unambiguously prove the existence of a mechanism for generating donors and acceptors. The research article offers a solution to this problem. Having the experimental results of the drift rate of the Fermi level as the activation energy (x) from the Fermi level to the valence band by calculating the distribution of the density of electronic states (DOS) sought the degree of compensation, which sets the direction and velocity of the Fermi level as close as possible to the experimental results. DOS calculations are performed for all variants of the location of atoms in the nodes of the unit cell, and the degree of occupancy of all positions by their own and/or foreign atoms. It turned out that for ErNiSb the most acceptable option is one that assumes the presence of vacancies in positions 4a and 4c of the Er and Ni atoms, respectively. Moreover, the number of vacancies in the position Er (4a) is twice less than the number of vacancies in the position Ni (4c). This proportion is maintained for Er1-xScxNiSb. Vacancies in the positions of Er (4a) and Ni (4c) atoms Er1-xScxNiSb are structural defects of acceptor nature, which generate two acceptor zones and in the semiconductor. The introduction of impurity Sc atoms into the ErNiSb structure by substituting Er atoms in position 4a is also accompanied by the occupation of vacancies by Sc atoms and a reduction in their number. Occupying a vacancy, the Sc atom participates in the formation of the valence band and the conduction band of the semiconductor Er1-xScxNiSb, acting as a source of free electrons. We can also assume that the introduction of Sc atoms into the structure of the compound ErNiSb is accompanied by a process of ordering the structure of Er1-xScxNiSb and Ni atoms occupy vacancies in position 4c. This process also, however, 2 times slower, leads to a decrease in the concentration of structural defects of acceptor nature. In this case, Ni, giving valence electrons, now act as donors.