FUNDAMENTAL PROBLEMS OF METROLOGY
The problem of increasing the accuracy of determining the magnetic moment of the potassium 39K nucleus, which is used in studies of the norm and pathology of living tissues by nuclear magnetic resonance methods, is considered. The paper presents experimental results for determining the resonance frequency ratio of water protons and 39K nuclei for KCl and KNO3 solutions at concentrations from 0.5 to 2 mol/kg of water. NMR signals from water protons and potassium nuclei were recorded simultaneously, which minimizes random and systematic errors in determining the ratio of the resonance frequencies to units of the eighth sign. When extrapolating the content of potassium salts in water to zero concentrations for single ions in water, it was determined 21.4300226(10). Using the known data for the magnetic moment of the proton and the data for proton shielding in water, we obtained 0.390962111(18). Shielding of potassium ions in water was previously calculated in the work of Antisera and others. When using these data on the shielding of potassium ions in water, the magnetic moment of the potassium core was obtained 0.391471(8). The comparison of the new result for μ( 39K) with the data of previous works is discussed.
GENERAL PROBLEMS OF METROLOGY AND MEASUREMENT TECHNIQUES
The problem of calibration of measuring instruments for given conditions based on the correction function is considered as a measurement problem of structural-parametric identification of the calibration diagram. It is shown, that the correction function allows at the first stage to obtain a ratio for correcting the readings, and at the second stage to obtain a corrected measurement result, it is necessary to identify the probability distribution of possible deviations from it. An example of solving the measurement problem of calibration for given conditions is given. Negative aspects of the practice of calibration of measuring instruments are noted: carrying out calibration under normal conditions according to the methods of verification of measuring instruments; presentation of calibration results by tables of joint readings of measuring instruments and standards; the presence in the calculations of the calibration diagram of significant restrictions on the mathematical apparatus of the «Guidelines for the expression of measurement uncertainty», specified by ISO/IEC 31010:2019 “Risk management – Risk assessment techniques”.
Several variants of half division two-dimensional method are proposed, which is the basis of a fundamentally new approach for constructing measuring instruments for sinusoidal or periodic electrical quantities. These measuring instruments are used in the diagnosis of electric power facilities. The most general variant, called midpoint method, is considered. The proposed midpoint method allows you to measure much smaller than using widespread methods, alternating currents or voltages, especially when changing the amplitude of the measured signal in very wide ranges, by 1–2 orders of magnitude. It is shown that using the midpoint method it is possible to suppress sinusoidal or periodic interference in the measuring path, in particular, to measure small alternating current when sinusoidal or periodic interference is 1–2 orders of magnitude higher than the useful signal. Based on the results of comparative tests, it was found that the current measuring device implementing the midpoint method is an order of magnitude more sensitive than the currently used high-precision measuring instruments.
The problem of modeling the process of functioning of redundant measuring instruments is considered. On the basis of the developed model, the determination of the frequency of verification of complex duplicated measuring instruments based on the semi-Markov model of the process of their functioning is justified. The relevance of the application of the theory of semi-Markov processes for modeling the functioning of redundant technical systems, including measuring instruments, is shown. A semi-Markov model of the process of functioning of measuring instruments has been developed, which allows us to take into account the influence of the frequency of verification, the provision of measuring instruments with spare elements, as well as the level of reliability and maintainability on the reliability of measuring instruments. A method is found for defining a semi-Markov process that correctly and adequately approximates the real process. The indicator of the effectiveness of the functioning of the measuring instruments and the corresponding modelis the availability factor of the measuring instruments.
OPTICOPHYSICAL MEASUREMENTS
In this paper important task of estimation of digital camera’s noise parameters is considered. Relation of accuracy of data obtained with digital camera and photosensor noise is discussed. Both standard European machine vision association EMVA 1288 and fast automatic segmentation of non-uniform target (ASNT) noise estimation methods are compared. Noise characteristics of machine vision PixeLink PL-B781F, scientific Retiga R6 and amateur mirrorless Canon EOS M100 cameras have been investigated. Accuracy of measurements, speed of calculation and experimental realization has been analyzed. Accuracy of temporal noise estimation by modifi ed ASNT method is no less than that one for standard EMVA 1288. But the ASNT method can be implemented much faster than the standard EMVA 1288 even with additional frames for accuracy improvement.
The article a the new design of flowing refractometer of differential type for media condition control both in laminar and turbulent flow regimes is considered. Given the peculiarities of the location of the flow and closed cuvette and the angles of incidence of laser radiation on their walls we have implemented a new method of measuring the refractive index n in new developed design of refractometer. This allowed us to make the influence of a number of errors related with unbalance voltage on the photoelectric converter, with an increase in the number of refl ections between optical elements of laser radiation, with the presence of a transport link for the selection of flowing fluid and temperature fluctuations on the result of measuring the refractive index. The technique allowing to reduce the influence of change of the optical density of the flowing liquid on the measurement error of refractive index is proposed. The results of experimental investigations for different media are presented.
THERMOPHYSIC MEASUREMENTS
The actual problem of accelerating and reducing the energy costs of the foam concrete slabs heat treatment technological process is considered. It is shown that to solve this problem, it is advisable to use the microwave radiation energy as a heat source. The main advantages of the microwave method of foam concrete slabs heat treatment in comparison with traditional methods are considered. The design of a microwave installation for the foam concrete slabs heat treatment has been developed. The installed microwave radiation sources have energy outputs in the form of a rectangular waveguide openings, which are used as radiating antennas. Huygens-Kirchhoff method was used to calculate the temperature distribution on the foam concrete slab surface; the method of loaded long lines was used to calculate the temperature distribution over the foam concrete slab thickness. A method for measuring the foam concrete slab temperature distribution is proposed. The results of theoretical and experimental temperature distribution studies on the surface and the cross-section of foam concrete slab with a width of 1500 mm, a height of 1000 mm and a thickness of 200 mm, a density of 1000 kg/m3 on the electromagnetic fields oscillation frequency of 2450 MHz are shown. The obtained experimental results showed a high efficiency of using microwave radiation for the foam concrete slabs heat treatment technological processes. Microwave technologies can be used for heat treatment of products made of concrete, reinforced concrete and polymer composite materials.
ACOUSTIC MEASUREMENTS
In this paper we consider the issues in implementations of interactive voice response systems with remote access. Their efficiency can be improved by automatically analyzing changes in the user's emotional state during the dialogue. In order to measure the indicator of the dynamics of the emotional statein real time, it is proposed to use the effect of sound (phonetic) variability of the user's speech at short intervals (fractions of a minute). The novel method of acoustic measurements in conditions of small samples has been developed based on information-theoretic approach by using a scale-invariant gain-optimized dissimilarity measure of the speech signals in the frequency domain. An example of its practical implementation in soft real time is considered. It is shown that the delay in obtaining the measurement results does not exceed in this case 10–20 sec. The experimental results confirmed the high speed of the proposed method and its sensitivity to changes in the emotional state under the influence of external noise. The proposed method can be used for automated quality control of voice samples of users in unified biometric systems, as well as to improve safety by non-contact identification of potentially dangerous persons with short-term psycho-emotional disorders.
PHYSICOCHEMICAL MEASUREMENTS
A comprehensive study to develop and create standard samples of the zeta potential unit of particles in a liquid in accordance with the requirements of GOST ISO 13099-2-2016 in the range of measured values from minus 150 mV to plus 150 mV was carried out. The existing standard samples of zeta potential in Russia and the world have been investigated; the analysis of the applicability of the starting materials and components for the creation of new standard samples has done. Samples based on modified polystyrene latex microspheres, bovine serum albumin and supramolecular systems based on aqueous solutions of L-cysteine, N-acetylcysteine, and silver acetate were considered as promising standard samples of the zeta potential of particles. All studies were carried out on equipment from the State Primary Standard of Dispersed Parameters of Aerosols, Suspensions and Powder Materials GET 163-2020 using the method of electrophoretic light scattering and measuring the pH value. It was found that polystyrene latex microspheres do not correspond to the requirements of the work in terms of developing a set of standard samples. Samples based on suspensions of bovine serum albumin do not correspond to the requirements of GOST ISO 13099-2-2016. Supramolecular systems based on aqueous solutions of L-cysteine, N-acetylcysteine, and silver acetate were proposed as standard samples. Such systems are characterized by the ability to modify the initial potential-determining layer of particles without changing their aggregate stability. Studies of the long-term stability of the developed standard samples of the zeta-potential unit of particles in a liquid have been carried out.
The problem of calibration of an analytical instrument and analysis procedure with an unknown composition and origin of the analyzed sample are considered. The transformation functions of the Zeeman atomic absorption spectrometer with electrothermal atomization have been investigated. The method for establishing a two-parameter transformation function of the spectrometer using a single calibration sample is proposed and the possibility of measuring the analyte concentration in a real sample using the refined transformation function of the spectrometer is considered.
The advantages and disadvantages of infrared and electrochemical gas analyzers for carbon dioxide CO2 are described. The possibility of using conductometric sensors with distilled water for monitoring the CO2 content in the air has been investigated. Two identical measuring systems were manufactured, each containing two open-type conductometric cells, a matching device and a personal computer. With the help of these complexes, experiments were carried out on the simultaneous measurement of the CO2 content in the air in two places (a laboratory room and a building in a forest, located at a distance of 15 km from each other) with deliberately different daily dynamics of the CO2 level change. A special experiment was carried out, which made it possible to obtain an estimate of the inertia of conductometric cells and a conversion factor for the values of CO2 content into standard units of measurement. It is shown that the daily dynamics of changes in the electrical conductivity of distilled water in open cells corresponds to the expected dynamics of changes in the CO2 content in the rooms where the measurements were carried out. The operability of the measuring complex and the possibility of creating on its basis a device for long-term monitoring of the CO2 content in the air mixture of gases has been confi rmed. The principal high selectivity of the measuring complex to CO2 in relation to other gases of the atmosphere has been established.
ISSN 2949-5237 (Online)