Вимірювальна техніка та метрологія. – 2021. – Випуск 82, №1

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Measuring Equipment and Metrology : scientific journal. – Lviv : Lviv Politechnic Publishing House, 2021. – Volume 82, № 1. – 44 р.

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    Hardware-software embedded system of signal frequency selection on gyrator
    (Lviv Politechnic Publishing House, 2021) Barylo Grygorii; Helzhynskyy Igor; Marusenkova Tetyana; Kryvenchuk Yurii; Khilchuk Mykola; Holyaka Roman; Boyko Oksana
    The work is devoted to the problem of frequency-selective signal conversion in microelectronic sensor devices. It has been shown that the signal path of such devices, in particular, sensor nodes in the concept of the Internet of Things, must meet the requirements of embedded systems using a mixed analog-digital front end. The analysis of the signal transformation of photovoltaic sensors, in particular the problem of a significant parasitic influence of extraneous non-informative optical radiation and electromagnetic interference, has been carried out. SPICE models of photovoltaic sensor signal circuits providing frequency selection on bandwidth filters have been synthesized. The main approaches of hardware-software implementation of the built-in system of frequency selection with the mixed-signal transformation are considered. The signal path of the embedded system includes a gyrator, a software-controlled amplifier, a synchronous demodulator, an analog-to-digital converter, and a digital filter. The implementation is carried out on the platform of the programmable system on a PSoC chip. The integrated circuits of the PSoC 5 LP Family Cypress Semiconductor Corporation are used with a wide range of programmable analog front-end nodes, in particular operating amplifiers, comparators, units on switching capacitors, reference voltage sources on the principle of the forbidden zone, analog multiplexers, signal synthesizers, etc. The efficiency of the mixed analog and digital signal conversion is shown. Key words: Signal Processing; Frequency Selection; Programmable System on Chip; Sensor Nodes Front-End; Optical Sensors in IoT concept.
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    Evaluation of natural gas quality by its calorific value
    (Lviv Politechnic Publishing House, 2021) Motalo Vasyl; Stadnyk Bohdan; Motalo Andriy
    The article develops and analyzes a method of the comprehensive evaluation of the quality of natural gas as an energy source. The method is based on establishing the calorific value of natural gas as a determinative index of its quality, taking into account all gas properties: both those that positively affect the gas calorific value and its energy content, and those that adversely affect. The generalized definition of natural gas quality as the degree to which the set of the own gas characteristics (component composition and physical properties) meet the requirements concerning energy content, safety, ecology, and other factors is given. The results of experimental researches on natural gas quality according to the developed procedure are also presented. Key words: Natural Gas; Energy Source; Natural Gas Quality; Index of Natural Gas Quality; Properties of Natural Gas; Calorific Value of Natural Gas.
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    Long-term stability of Co-C and Pd-c eutectic fixed points for thermocouples calibration
    (Lviv Politechnic Publishing House, 2021) Abdelaziz Yasser A.; Megahed F. M.; Abdel-Aal M. M.
    Eutectic fixed points are close to becoming a reference for high temperatures calibration, especially as the new International Temperature Scale (ITS) approach to issue after the re-definition of the Kelvin unit. In this work, the long-term stability of Co-C and Pd-C eutectic fixed points were investigated using NIS-Egypt facilities. The eutectic points were measured using Pt/Pd thermocouple. The total exposure to the Co-C and Pd-C melting temperature was about 200 h for the fixed-point cell and 150 h for the Pt/Pd thermocouple. The EMFs of the thermocouple at the melting point was observed to drift by about 0.25 °C. Realization uncertainties were estimated to be ~0.446 °C for Co-C and ~0.742 for Pd-C (k = 2). Results show that Co-C and Pd-C eutectic cells can exhibit long-term stability. Key words: Eutectic Fixed Points; Stability; Thermocouples; Uncertainty.
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    Kinetic and energetic performances of thermometric material TiCo1-xMnxSb: modelling and experiment
    (Lviv Politechnic Publishing House, 2021) Krayovskyy Volodymyr; Pashkevych Volodymyr; Rokomanyuk Mariya; Haranuk Petro; Romaka Volodymyr; Stadnyk Yuriy; Romaka Lyubov; Horyn Andriy
    The results of a complex study of the semiconductor thermometric material TiCo1-xMnxSb, x=0.01–0.10, for the production of sensitive elements of thermoelectric and electro resistive sensors are presented. Microprobe analysis of the concentration of atoms on the surface of TiCo1-xMnxSb samples established their correspondence to the initial compositions of the charge, and X-ray phase analysis showed the absence of traces of extraneous phases on their diffractograms. The produced structural studies of the thermometric material TiCo1-xMnxSb allow to speak about the ordering of its crystal structure, and the substitution of Co atoms on Mn at the 4c position generate structural defects of acceptor nature. The obtained results testify to the homogeneity of the samples and their suitability for the study of electrokinetic performances and the manufacture of sensitive elements of thermocouples. Modeling of structural, electrokinetic, and energetic performances of TiCo1-xMnxSb, x=0.01–0.10, for different variants of the spatial arrangement of atoms is performed. To model energetic and kinetic performances, particularly the behavior of the Fermi level , the bandgap , the density of states (DOS) distribution was calculated for an ordered variant of the structure in which Co atoms at position 4c are replaced by Mn atoms. Substitution of Co atoms (3d74s2) by Mn (3d54s2) generates structural defects of acceptor nature in the TiCo1-xMnxSb semiconductor (the Mn atom contains fewer 3d- electrons than Co). This, at the lowest concentrations of impurity atoms Mn, leads to the movement of the Fermi level from the conduction band to the depth of the bandgap . In a semiconductor with the composition TiCo0.99Mn0.01Sb, the Fermi level is located in the middle of the bandgap , indicating its maximum compensation when the concentrations of ionized acceptors and donors are close. At higher concentrations of impurity Mn atoms, the number of generated acceptors will exceed the concentration of donors, and the concentration of free holes will exceed the concentration of electrons. Under these conditions, the Fermi level approach, and then the level of the valence band TiCo1-xMnxSb cross: the dielectric-metal conductivity transition take place. The presence of a high-temperature activation region on the temperature dependence of the resistivity ln(ρ(1/T)) TiCo1-xMnxSb at the lowest concentration of impurity atoms Mn, x=001, indicates the location of the Fermi level in the bandgap of the semiconductor thermopower coefficient α(T,x) at these temperatures specify its position - at a distance of ~ 6 meV from the level of the conduction band . In this case, electrons are the main carriers of current. The absence of a low temperature activation region on this dependence indicates the absence of the jumping mechanism conductivity. Negative values of the thermopower coefficient α(T,x) TiCo0,99Mn0,01Sb at all temperatures, when according to DOS calculations the concentrations of acceptors and donors are close, and the semiconductor is maximally compensated, can be explained by the higher concentration of uncontrolled donors. However, even at higher concentrations of impurity Mn atoms in TiCo0,98Mn0,02Sb, the sign of the thermopower coefficient α(T,x) remains negative, but the value of resistivity ρ(x, T) increases rapidly, and the Fermi level deepens into the forbidden zone at a distance of ~ 30 meV. The rapid increase in the values of the resistivity ρ(x, T) in the region of concentrations x=0.01–0.02 shows that acceptors are generated in the TiCo1-xMnxSb semiconductor when Co atoms are replaced by Mn, which capture free electrons, reducing their concentration. However, negative values of the thermopower coefficient α(T,x) are evidence that either the semiconductor has a significant concentration of donors, which is greater than the number of introduced acceptors (x=0.02), or the crystal simultaneously generates defects of acceptor and donor nature. The obtained result does not agree with the calculations of the electronic structure of the TiCo1-xMnxSb semiconductor. It is concluded that more complex structural changes occur in the semiconductor than the linear substitution of Co atoms by Mn, which simultaneously generate structural defects of acceptor and donor nature by different mechanisms, but the concentration of donors exceeds the concentration of generated acceptors. Based on a comprehensive study of the electronic structure, kinetic and energetic performances of the thermosensitive material TiCo1-xMnxSb, it is shown that the introduction of impurity Mn atoms into TiCoSb can simultaneously generate an acceptor zone (substitution of Co atoms for Mn) and donor zones and of different nature. The ratio of the concentrations of ionized acceptors and donors generated in TiCo1-xMnxSb will determine the position of the Fermi level and the mechanisms of electrical conductivity. However, this issue requires additional research, in particular structural and modeling of the electronic structure of a semiconductor solid solution under different conditions of entry into the structure of impurity Mn atoms. The investigated solid solution TiCo1-xMnxSb is a promising thermometric material. Key words: Electronic structure; Resistivity; Thermopower.
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    Study of thermal stability of metal glasses of metal – metal and metal – metaloid systems for thermometry purposes
    (Lviv Politechnic Publishing House, 2021) Stadnyk Bohdan; Skoropad Pylyp; Nakonechnyi Yuriy; Myhaylov Vitaliy
    The metastable metallic glasses are studied in the paper. Their properties as the material for producing the sensitive elements of thermometric transducers depend on the peculiarities of manufacturing the mentioned material. The selection of modes of glass production and the correction of modes facilitates to increase in the operating temperatures of the transducers or/and extends their service life. Key words: Metal amorphous alloy; Metastable material; Sensitive element; Thermoelectric transducer.
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    Establishment of permissible limits for leaching substances from bone substitutes containing hydroxyapatite and beta-tricalcium phosphate
    (Lviv Politechnic Publishing House, 2021) Chernobrovchenko Vadym; Dyadyura Kostiantyn; Balynskyi Mark
    It has been proven that the main factor in the uncertainty of laboratory results is biological variation, that is, a change in the composition of human biomaterials, reflecting the course of life processes in the body and is characterized by a combination of the constancy of the internal environment and dynamic fluctuations around the homeostasis point. The paper offers objectively substantiated recommendations for the accuracy of laboratory tests, established maximum allowable values of analytical errors of quantitative research methods (measurements) of physical quantities (composition and properties of components of biological materials, analytes) in samples of biological materials. The interpretation of LOD and LOQ for detecting the concentration of leaching micro-impurities in the bioliquid. The identified patterns indicate that the elements of micro impurities have different dissolution rates. The ratio of hydroxyapatite/tricalcium phosphate affects the dissolution rate of the material: the higher the content of β-tricalcium phosphate, the higher the dissolution rate. The results of the research allow establishing recommendations for reducing inaccuracies in determining the composition of bone substitutes based on hydroxyapatite/β-tricalcium phosphate, which is associated with manifestations of biological variation, reflecting the body’s response to various environmental factors and subject to statistical laws. Key words: Standardization; Validation method; Limit of detection; Limit of quantification; Bone substitutes.
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    Position-sensitive photodetector array for optical coordinator
    (Lviv Politechnic Publishing House, 2021) Verbitskiy Volodimir; Voronko Andriy; Verbitskiy Dmytro
    New position-sensitive matrices for an optical coordinator and a method for determining the coordinates of a light spot for micromovements are presented, an analysis of the topologies and direction-finding characteristics of the proposed matrices is shown. Key words: Optical coordinator; Position-sensitive matrix; Method for determining coordinates; Position-sensitive detectors; Quadrant photodiodes; Direction-finding characteristics.