Abstract: The study analyzes the errors of the measuring optical power divider of laser radiation. This divider is used to transmit a unit of average power of high-intensity laser radiation and is structurally designed as a wedge. The error of the division factor, which affects the accuracy of the unit transmission, is determined. The random component of the division factor error estimation is assessed. A determination method based on the rearrangement of the measuring instruments used is proposed to provide the most probable estimate. The error caused by the nonlinearity of the measuring instruments used to determine the division factor is investigated, and its largest interval is estimated. In case of invariability of the conversion coefficients of the measuring instruments used on the laser radiation power, the method excludes the dependence of the error in determining the division factor on the said coefficients and reduces their influence on the transmission error. The possibility of controlling the divider division factor by determining the control parameter and its confidence interval when transmitting a radiation power unit is substantiated, and a formula for calculating this interval in each measurement cycle is obtained. The parameter value and the change in confidence interval can be used to control the reliability of the transmission of a power unit to the calibrated measuring tool in real time. PubDate: 2021-01-13

Abstract: The design and principle of operation of a multi-sensor converter of binary mechanical signals into electrical signals based on a partitioned fiber-optic digital-to-analog converter with parallel structure are considered. The digital-to-analog converter is made from a set of simple and fiber-optic digital-to-analog sections adaptable to streamlined production (three- and five-bit). The advantages of the optical layout of the proposed converter on metrological and energy characteristics, in comparison with unary multi-bit converters, are substantiated. It is shown that as a result of an increase in the number of digital-to-analog sections, it is possible to increase by a large factor the information capacity of the multi-sensor converter without tightening the requirements for its manufacturing design and component base. A mathematical model of the proposed converter has been developed that reflects the features of functioning under conditions of time-sequenced conversion of the input mechanical code vectors of the separate fiber-optic sections into electrical analogs, and generating a resultant output code vector. The developed mathematical model can be used at the design phase for converters of binary mechanical signals, in order to obtain extensive and deep information on the engineering prospects of the future product, without resorting to expensive physical experiment. PubDate: 2021-01-13

Abstract: This paper reviews methods used for measuring the vibration of dynamic objects, including a promising method for non-contact vibration diagnostics based on Doppler microwave sensors. The method involves actively irradiating an object with electromagnetic waves and applying a two-channel quadrature processing to the reflected signal received. The article also discusses modes of analysis of the subtle resulting signal using spectral or wavelet transformations depending on the nature of the active vibration. The advantages of this non-contact and remote vibration analysis method for studying complex dynamic objects are described. Finally, we evaluate the applicability of this method in machine learning and intelligent systems employed for the non-destructive continuous monitoring of the state of complex dynamic objects under vibration. PubDate: 2021-01-13

Abstract: The ratio of NMR frequencies of lithium isotopes f(7Li)/f(6Li) = 2.6409061846(13) was determined with an error of 4.9·10–10. The use of a nuclear magnetic resonance spectrometer operating in the mode of simultaneous registration of signals from two nuclei to obtain data allowed the random and systematic errors in the measurement results to be reduced by an order of magnitude. The ratio of the resonant frequencies of water protons and 7Li ions was determined: f(H2O)/f(7Li) = 2.557100473(9) with an error of 3.5·10–9 for solutions with an extremely low concentration of LiOH*H2O salt in water and at a temperature of 25°C. Based on the obtained data, the magnetic moments of lithium nuclei were calculated: μ(6Li) = 0.8220454(25)μN, μ(7Li) = 3.2564171(98)μN. The known data on the magnetic moment of the proton and data on the electronic shielding of these nuclei were used. A comparison of the experimental data for μ(6Li) and μ(7Li) and the corresponding theoretical calculation data was performed. PubDate: 2021-01-13

Abstract: A novel solution to the problem of estimating nonlinear parameters is presented. The peculiarity of this problem is that the arguments of a nonlinear function comprise not only the measurement data and required parameters, but also supplementary parameters. Although supplementary parameters are a priori unknown, they are necessary for obtaining optimal estimates of the required parameters, which is carried out according to the point-mass method as a weighted sum of partial estimates obtained for the specified values of supplementary parameters. The considered solution allows priori probabilities for supplementary parameters to be rejected by taking into account additional covariance of weighting coefficients and (or) specified partial estimates. The described approach is effective in solving specified nonlinear estimation problems characterized by low accuracy of available measurement data and (or) their few number. PubDate: 2021-01-12

Abstract: Questions related to control of the performance of a measuring techniques are considered. Analytic and computer models of false failure and undetected failure (error functions) in tolerance control of the parameters of the components of a measuring technique are developed. A geometric interpretation of error functions in the form of two-dimensional surfaces that depend on the tolerance of a controllable parameter and the measurement error is presented. The newly developed models may be used both for theoretical as well as statistical laws of distribution of a measurable quantity and a measurement error. The results obtained will be useful in the development of metrological support of a measuring technique, performance of verifications of measurement instruments, metrological examination of technical documentation, and certification of measurement methods. PubDate: 2021-01-12

Abstract: The article describes noncontact measurement tools for the vibration parameters of various products. The characteristics of noncontact sensors for measuring displacements, deformations, and vibration parameters with operating principles of different physical nature were compared. In the model of diffuse-specular reflection, the efficiency of optocouplers for the development of noncontact vibration displacement sensors was substantiated. The urgent tasks of research and development of sensors using near infrared (IR) radiation reflected from the controlled object surface were formulated. A research methodology based on contemporary algorithms and means of digital processing of vibration signals was proposed. Difficulties in studying the metrological characteristics of sensors in broad dynamics and frequency ranges using electrodynamic shaker boards were discussed. The results of a field study of the main metrological characteristics of an optoelectronic sensor prototype providing measurement of displacements with an amplitude of up to 5 mm in the frequency range of 0–3000 Hz were presented. The results of the analysis of amplitude-frequency characteristics of the sensor in the range of 5–3000 Hz, obtained with the use of two disks manufactured using a 3D printer, were presented. The advantages and disadvantages of noncontact sensors based on IR optocouplers were discussed. PubDate: 2021-01-12

Abstract: A unified program for processing the calibration protocol data of a measurement instrument under normal conditions is developed. The result of the calibration contains a calibration function (function of corrections in the form of a continuous power series) and a calibration chart based on typical probability distributions of an additive error. The problem of statistical processing of the calibration protocol data of a measurement instrument under normal conditions within the framework of the MMI–calibration 3.0 unified program is solved. An example of a calibration of a thermometer by a third-grade working standard by means of the newly developed MMI–calibration 3.0 program is presented. PubDate: 2021-01-11

Abstract: This paper reports the application of neural networks in various fields of activity. In specific, it describes the use of neural networks to process phasechronometric measurement information. The novelty of the proposed approach lies in the choice of a classification attribute and the use of a perceptron algorithm for binary classification. The simplest binary classification of the lathe operating modes (idle or cutting) is presented. PubDate: 2021-01-11

Abstract: The error in measuring heat capacity owing to heat exchange of the gas during the stage of determining the thermal equivalent of the empty calorimeter is discussed. A correct formula is obtained for estimating the correction to the measured heat capacity of a test sample and the error arising from neglect of the correction for the heat-exchanger gas is evaluated numerically. Numerical estimates of the error are obtained for the KA-S4 standard calorimeter contained in the State Primary Standard GET 60-2019 for the unit of specific heat in solids. PubDate: 2021-01-11

Abstract: The need to account for a misalignment between the heat flux density and temperature gradient vectors when studying thermal conductivity of anisotropic materials was analyzed. A method for measuring thermal conductivity of pyrolytic graphite (grade UPV-1) in the direction parallel to the precipitation plane was proposed. The advantage of the proposed method is the possibility to determine thermal conductivity of pyrolytic graphite in the direction parallel to the precipitation plane while accounting for a misalignment between the heat flux density and temperature gradient vectors. The test samples were shaped as hollow cylinders with the pyrolytic graphite precipitation plane located along the radius of the cylinder. The heat flux density was determined based on the radiation heat flux emitted from the outer surface of the sample, and the temperature gradient was calculated along the radius, which made it possible to maintain the alignment between the heat flux density and temperature gradient vectors. A comparative analysis of the thermal conductivity values obtained in this study (parallel to the precipitation plane) and those reported in the reference sources was performed. The studied temperature range was extended into the higher temperature region by 450 K and constitutes 1900–2950 K. PubDate: 2021-01-11

Abstract: We review a variety of contactless techniques for fluid viscosity measurement. We discuss contactless aero-hydrodynamic techniques capable of providing high-accuracy viscosity measurements for non-homogeneous and non-transparent fluids over the range 2–100 Pa·s. We describe a very promising approach in need of additional work–a contactless aero-hydrodynamic technique that involves using a pulsed gas jet to distort the surface of the fluid being measured and determining the viscosity based on the time required to reach a specified deformation level after the gas jet comes on. We have developed a contactless aero-hydrodynamic device with a laser triangulation detector to measure the range to the surface of the liquid; this viscosity measurement device supports full automation, while providing a significant increase in measurement accuracy. We studied four possible options for implementation of the device, and selected the best option to improve the measurement accuracy and reduce the sensitivity of the device to external effects. We describe the design and operating principle for the device, and describe how device design parameters affect systematic and random measurement error. The relative measurement error in fluid viscosity was 2% or less over the entire range from 2 to 100 Pa·s. This contactless aero-hydrodynamic device will be useful for measurement of viscous fluids in a wide variety of industrial fields. PubDate: 2021-01-11

Abstract: Problems of calibrating the instruments for measuring infrasound fluctuations in the atmosphere are considered. The influence of external conditions, including atmospheric pressure, relative humidity and air temperature, on the sound pressure reproduced in the measuring chambers of the pistonphone in the frequency range from 0.001 to 250 Hz is estimated. The errors in calculating the sound pressure in the pistonphone measuring chambers are estimated under various external conditions. Special requirements for the system for maintaining the required external conditions are given. PubDate: 2021-01-11

Abstract: The paper discusses practical application of spectral pyrometry for controlling the temperature of a dielectric object subjected to heating in a high-intensity microwave electromagnetic field. The authors describe the advantages of using spectral versus color and brightness pyrometry when measuring high temperatures (500°C and above). To eliminate a negative impact of the electromagnetic field on a fiber-optic cable, which is exposed to thermal radiation from a microwave field-heated object and may fail in case of overheating, it is proposed to place a below-cutoff waveguide inside instead of outside of the microwave heating chamber. It is shown that such solution completely eliminates the negative impact of the electromagnetic field on the fiber-optic cable and allows positioning the receiving end of the cable in close proximity to the heated object. A calculation of geometric parameters of the below-cutoff waveguide is provided given the operating frequency of the electromagnetic field of 2450 MHz. PubDate: 2021-01-11

Abstract: The application of the methods of electromagnetic sounding for geophysical research is considered. The results of synchronous measurements of the Earth’s electric and magnetic fields made by different types of sensors in the frequency range of 0.002–7000 Hz are presented. Various approaches to obtaining the estimate of sensor noise are considered. A technique for quantitative estimation of the self noise level of the sensors under study and the characteristics of the natural field on the basis of two- and three-channel schemes of synchronous measurements is proposed. Comparison of experimental noise estimates with computational data is given. It is shown that the magnetometer based on a magnetomodulation transducer has an unacceptably high level of self noise for using it in applications related to the measurement of natural variable magnetic field. PubDate: 2021-01-11

Abstract: This is a review of high-frequency methods for measuring and controlling the humidity of various materials. The moisture of cotton seeds is a major factor affecting their qualitative and quantitative characteristics in technologies for their storage, transport, and processing. Thus, direct humidity measurements of cotton seeds during processing is an important problem. A mathematical model of a high-frequency hygrometer for cotton seeds is constructed in which the test material is represented as a complicated dielectric in an electric field. A substitution circuit containing a capacitance between electrodes is proposed, along with capacitances and resistances corresponding to different forms of polarization. Four variants of the substitution circuit are examined which approximately describe the dependence of the tangent of the dielectric loss angle on the frequency of the electromagnetic field. It is shown that the simplest parallel two-component RC substitution circuit corresponds most closely to the actual object of measurement at frequencies of 105–108 Hz. PubDate: 2021-01-11

Abstract: One of the most important problems in the diagnostics of multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the results of monitoring the electrical and geometric parameters of these materials. Results are presented from a study of the potential informativeness of a multifrequency radio-wave method for slow surface electromagnetic waves for reconstruction of the electrical and geometric parameters of multilayer dielectric coatings. A simulation model is shown for evaluating the accuracy of reconstructing the electrical and geometric parameters of multilayer dielectric coatings. The model takes into account the electrical and geometric parameters of the coating, the level of noise in the measurement data, and the measurement bandwidth. Simulation modeling and experimental test data for the reconstruction of the relative dielectric constants and thicknesses of one- and two-layer equal-thickness dielectric coatings based on polymethyl methacrylate, ftoroplast (teflon) F-4D, and RO3010 for different values of the mean square deviation of the noise level in the measured attenuation coefficients for the field of a slow surface electromagnetic wave. The accuracy of the reconstruction of the geometric and electrical parameters of the layers is found to decrease as the number of estimated parameters and the noise level increase, as well as when the dielectric constant and thickness of the layers are reduced. Experimental data confirm the adequacy of the simulation model developed here. This model can be used for a specific measurement complex employing a multifrequency radio-wave technique for slow surface electromagnetic waves to estimate quantitatively the potential possible accuracy of reconstructing the geometric and electrical parameters of multilayer dielectric materials and coatings. A simulation model and experimental study of a multilayer dielectric coating show that for a measurement bandwidth of 1 GHz the errors in estimating the dielectric constants and thicknesses of the layers do not exceed 10% with a confidence coefficient of 0.95 for a mean square deviation of 0.003–0.004 in the noise level. PubDate: 2020-12-01

Abstract: The composition, operating principle, and basic metrological characteristics of GET 186–2017, the State Primary Standard of units of ellipsometric angles, a Standard that supports measurement of the two-dimensional spatial distribution of ellipsometric angles, are described. The structure of GET 186–2017 includes a spectral ellipsometer equipped with a x, y-stage for measurements on a grid of 10 × 10 points and an interference profilometer by means of which a two-dimensional map of deviations from 90° of the normals to the surface of an object may be measured. Measurements are not performed at scanning points where the deviation of the normal exceeds 0.01°. Through measurement of the two-dimensional spatial distribution of ellipsometric angles it is possible to establish the spatial distribution of the thickness and complex indicator of refraction of the coatings across the area of a test article. GET 186–2017 supports the uniformity of measurements in highly important trends in science and technology, such as microelectronics, optics, and instrument construction. The principal users of GET 186–2017 are organizations involved in the development of new articles in microelectronics, solar batteries, and optics, in particular, laser gyroscopes. Ordered multilayer structures deposited on a substrate where the thickness of these structures is monitored by means of different types of ellipsometers, including image ellipsometers, are components of such structures. PubDate: 2020-11-28

Abstract: Results of studies designed to improve GET 8–2011, the State Primary Standard of the units of air kerma, air kerma rate, exposure, exposure rate, and energy flux of x-radiation and gamma radiation, are described. The studies are performed in 2019 to implement the recommendations of Report No. 90, Key Data for Dosimetry of Ionizing Radiation: Standards and Applications, International Commission on Radiation Units and Measurements. The following changes are introduced into the equation for reproduction of the units of quantities in GET 8–2019: in the field of x-radiation, new correction factors for free-air ionization chambers are introduced and the value of the relative standard uncertainty of the mean ionization energy is changed; in the field of gamma radiation, the values of the product of the mean ionization energy and ratio of the mass stopping powers of graphite to air in measurements with cavity ionization chambers are changed. More accurate values of the units of quantities reproduced by GET 8–2019 are obtained. PubDate: 2020-11-28

Abstract: Problems arising in the measurement of the parameters of the response speed of current broadband photodetectors by the method based on measurement results of the rise time of transitional characteristics. A method is proposed for quantitative estimate of response speed, using the results of the determination of impulse response of a photodetector being examined. A pulsed fiber optic laser operating in a condition of self-synchronization of modes, and providing the generation of ultrashort (approximately 3 ps) optical pulses, serves as the source of measurement signals. A measurement installation that makes it possible to implement the proposed method of measurement is provided. Certain results of experimental testing of the method are given. PubDate: 2020-11-27