The necessity and relevance of precision pulse pressure measurements in industry (high-speed technological processes) and transport (existing and new types of engines) is shown. The device, the principle of operation and the result of metrological studies of the State Primary Standard of the unit of overpressure in the range of static pressure from 10 to 1600 MPa and in the range of pulse pressure from 1 to 1200 MPa and the effective area of piston pairs of piston pressure gauges in the range from 0.05 to 1 cm² GET 43-2022 are presented. The GET 43-2022 includes hydraulic and pneumatic installations, as well as an ultra-high pressure valve designed to compare installations from the GET 43-2022 composition working with different standard fl uids in the range of 250-1200 MPa. The reproduction range of the pulse pressure unit GET 43-2022 is 1-1200 MPa. The method of reproducing the pulse pressure unit in liquid and gas media using hydraulic and pneumatic installations is described. The metrological characteristics of GET 43-2022 are investigated, the budget of measurement uncertainty is calculated when reproducing the pulse pressure unit. The results obtained make it possible to meet the needs of the development of a fl eet of working standards for pulse pressure measuring instruments traceable to GET 43-2022.

The article shows the need to develop methods and tools for realization and transferring a unit of heat quantity in the fi eld of measuring small thermal effects of physical and chemical interactions  by the method of isothermal titration calorimetry. The relevance of the work is due to the wide application of measuring instruments implementing this method and the lack of standardized metrological procedures and tools. To solve the problem of ensuring unity and traceability of measurements in this fi eld, VNIIM calorimetry laboratory conducted research to expand the functional and measuring capabilities of the State primary special standard of the unit of heat quantity in the fi eld of solution and reaction calorimetry GET 133-2012. In the course of work a reference titration microcalorimeter MKT was developed, investigated, and included in the GET 133-2012. Microcalorimeter MKT was designed to realize, store, and transfer a unit of heat quantity in the fi eld of measuring small thermal effects in liquid media. As a result of microcalorimeter studies, the capability of realizing and transferring a unit of heat quantity in a new range was confi rmed: from 100 to 5000 μJ with an expanded uncertainty from 1.2 to 8.6 %. The improved GET 133-2012 with an updated composition and new metrological characteristics was approved as the State primary special standard of the unit of heat quantity in the fi eld of solution and reaction calorimetry GET 133-2023. This lays the foundations for the creation of new metrological tools and procedures for transferring the unit of heat quantity in the fi eld of solution and reaction calorimetry.

The metrological support of measuring current converters as the main elements intended for measuring a large electric current is considered. Brief historical information about the creation of the State primary standard of units for electric current intensity conversion coeffi cients is given. The composition and metrological characteristics of the State primary standard of units for electric current intensity conversion coeffi cients GET 152-2023 are presented. The equations of measurements and the results of the studies of two standard measuring installations created as part of the improvement of GET 152-2023 from 2019 to 2022 are given. It is shown that the range of reproducible rated primary currents of a sinusoidal current installation is 1–1000 A in the frequency range of 40–2500 Hz, and the range of reproducible rated primary currents of a high direct current installation is 1000–10000 A. The data on the state verifi cation scheme for measuring instruments of the electric current conversion coeffi cients are given. Comparisons with the participation of UNIIM as a pilot for the period from 2019 to the present are listed. The prospects of further improvement of the GET 152-2023 to expand the measurement and calibration capabilities of this fi eld of measurement in the Russian Federation are described. The results of the work are relevant for metrological support of measuring converters of large electric current used in power engineering and industry.

The article is devoted to the development of phase triangulation and structured illumination methods for measuring the geometry of objects with arbitrary light-scattering surface properties. A method for expanding the dynamic range of a measuring system that implements the phase triangulation method is proposed. The method is based on automatic adjustment of the exposure time of the photodetector, excessive collection of experimental data, and complex regression analysis. The results of experimental studies of the effectiveness of the proposed method for expanding the dynamic range of the measuring system are presented. It is shown that the classical approach to image interpretation using a photodetector with a fi xed exposure duration almost always leads to a high level of error over the entire range of light-scattering properties of the surface. For low exposure values, there is an increase in the measurement error in the region of the dark surface, since the signal level there turns out to be signifi cantly weaker than for the bright regions of the measured surface. For large exposure values, an increase in the error is observed when measuring the bright area of the measured surface, since the signal is outside the dynamic range of the photodetector. The proposed method of image interpretation with an extended range of the measuring system demonstrates an error level less than or comparable to the results of image interpretation with a fi xed exposure for all measured light-scattering properties of the surface. 

The proposed method makes it possible to perform automated measurements without additional optimization of the photodetector parameters for the light-scattering properties of the surface of the measured object. 

The article considers a method for measurement the parameters of the microrelief of the surface of machine parts by optoelectronic and computer means, as an integral part of the technological process of manufacturing machine parts with precision surfaces. The method is based on computer processing of images of the studied microreliefs, considered as a set of realizations of a stationary random process. The number of realizations of the random process is assumed to be equal to the number of lines in the analyzed microrelief image. The microrelief image is considered as a matrix of random numbers. For this matrix, mathematical expectations, variances, standard deviations, correlation moments and the normalized autocorrelation coeffi cient of honey are calculated for the columns of the matrix. To conduct research on the proposed method, an optical-electronic complex was used, consisting of an instrumental microscope with a video camera and a computer for digital processing of the obtained images of the microrelief of reference samples with different roughness. The surface roughness Ra was estimated by standard methods on a profi lometer and ranged from 0.025 μm to 0.13 μm. When developing software for correlation-spectral image processing, OpenCV tools and the C++ language were used. According to the research results, it was found that the nature of the correlation functions is largely determined by the parameters of the studied microreliefs. To identify the studied microreliefs, we determined the analytical dependences of the arithmetic mean deviation of the microrelief surface profi le both on the average value of the variable component of the autocorrelation function and on the values of its spectral density. It has been established that for measuring the Ra microrelief by optoelectronic means, the most promising is the use of the spectral density of its autocorrelation function, calculated from its halftone image. The results of determining the parameters of the microrelief of the surfaces of the raceways of the inner rings of instrument bearings are presented.

The problem of studying the characteristics of the surface of heat-resistant steel samples after electrical discharge machining is considered as one of the most common and effective methods for manufacturing hard-to-machine parts, depending on the processing parameters. For the purposes of the study, samples were processed on an electrical discharge machine in various processing modes in accordance with a full-factorial experimental plan, which makes it possible to implement all possible combinations of processing parameters. To assess the state of the treated surface, the surface roughness of all obtained samples was measured in the longitudinal and transverse directions. The results of the analysis of the evaluation of the obtained surface roughness profi les are presented. The previously known conclusion that the average height of irregularities increases with increasing pulse current is confi rmed. It has been established that, along with this, the fractal dimension of the profi le also changes in the scale range of 20–500 μm, calculated on the basis of the “area – scale” function. A spectral analysis of microroughnesses based on the accumulated spectral power of the surface roughness profi le of steel samples was carried out, as a result of which it was shown that the main contribution to their formation is made by spatial frequencies in the range up to 0.05 μm^–1. The results obtained will be useful in planning the modes of electrical discharge machining, depending on the functional purpose of the surfaces.

Metrological support of digital electronic voltage transformers and low-power voltage transformers (sensors) is represented. The methods and reference measuring instruments of the State primary special standard of units of the ratio error and the phase displacement of AC electric voltage of power frequency in the range from to and units of electric capacitance and tangent of loss dissipation factor at AC voltage of power frequency in the range from 1 to 500 kV – GET 175-2023, used for metrological support of the measuring instruments mentioned above. The results of research of GET 175-2023 are presented. The expanded uncertainties of GET 175-2023 when reproducing the units of the ratio error and the phase displacement of AC electric voltage of power frequency for metrological support of analog low-power voltage transformers (sensors) include the budget of the uncertainties of the current comparator, low-voltage (reference) and high-voltage measuring measures, the high-voltage MVE-01 bridge (SA7400MA1 amplifi er) and are respectively 9.62·10^–5 and The expanded uncertainties of GET 175-2023 when reproducing the units of the ratio error and the phase displacement of AC electric voltage of power frequency for metrological support of electronic digital voltage transformers and digital low-power voltage transformers (sensors) include the budget of uncertainties of the converter «high voltage – current», converter «current – low voltage», converter «low voltage – a digital copy of voltage», a digital comparison device and constitutes 10.8·10^–5 and respectively. GET 175-2023 allows solving the problems of metrological support of electronic digital voltage transformers and digital low-power voltage transformers (sensors).

The division of total losses in electrical steel of the magnetic circuit of electric machines into three components is considered: hysteresis, classical eddy current and anomalous eddy current. The solution to this technical problem will make it possible to effectively design and construct electrical machines with magnetic cores having low magnetic losses. At present, such a separation of losses is associated with time-consuming measurements on special equipment and is performed with large errors. Each of these components depends differently on the magnetization frequency and temperature, and these dependences are known. Based on this, the paper proposes two methods for determining losses in steel – the method of three frequencies and the method of three temperatures. In order to fi nd three unknown quantities, three no-load experiments are proposed, carried out at three frequencies or at three temperatures of electric machine cores. Using the results of measurements of active powers spent on core heating, expressions of hysteresis, eddy-current classic and eddy-current anomalous losses are obtained. The results of the experiments carried out by the method of three frequencies and the method of three temperatures agree well with each other, which confi rms the adequacy of the methods and the possibility of their application in practice. The article analyzes the advantages and diffi culties of implementing each method. The methods can be applied to effectively minimize losses in the steel of electrical machines.

As a result of primary pressure calibration (by reciprocity technique or by pistonphone method) of LS-type microphones, their corresponding complex sensitivity is determined. However, one of the problems of this procedure is the need to theoretically determine the complex acoustic impedance of air enclosed in a closed volume. As experiments and various theoretical works have shown for almost 100 years of studying the above-mentioned problem, the adiabatic approximation of acoustic oscillations, adopted at the beginning, is not correct. The most signifi cant (in the fi rst approximation) infl uencing factors, due to which the adiabatic approximation alone is not correct, are the heat exchange of air inside a closed volume with the external environment (through the walls of a closed volume) and refl ected waves that appear at high frequencies (as the length of the closed volume and the wavelength of oscillations are compared). Numerical simulation is proposed to study these factors. The numerical algorithm is based on the regularized NavierStokes equations with quasi-gas-dynamic approach, taking into account viscosity, thermal conductivity and compressibility of air. In this paper, the phase of the complex acoustic impedance of air in a closed volume with heat-conducting and heat-insulated walls is determined. The results of the study are relevant both for calibration of measurement microphones at low and infrasound frequencies by the pressure reciprocity technique and the pistonphone method, and for studying acoustic processes in liquid and gaseous media using numerical modeling. Measurement devices that was transmitted the unit of sound pressure in the air from measurement microphones calibrated by the primary method are used, for example, when monitoring noise from various sources (industrial activity, transport), 

Artifi cial intelligence as one of the main elements of digital transformation and promising directions of its application in metrology are considered. The main attention is paid to the application of artifi cial neural networks as a part of measuring instruments and measurement systems for obtaining measurement results in cases when the measurement function is unknown, not suffi ciently defi ned or too complicated for algorithmic formalization. More often in practice we meet problems with partially uncertain function, when in addition to the deterministic basis there is an additional unknown component that has a signifi cant impact on the measurement result. A simulation experiment was conducted to solve such a measurement problem using a neural network model. In the experiment, a measurement function with a linear deterministic basis and an additional nonlinear component of about 10 % of the relative standard deviation, that was implied by the unknown when the model was created, was used. The results of the experiment confi rmed the practical possibility and high effi ciency of using artifi cial neural networks to solve such measurement problems. The neural network model in the conditions of a noisy training sample, corresponding to real measurement conditions, almost completely restored the measurement function despite the fact that a linear neural network model was used, and the additional component of the measurement function was nonlinear. In this particular experiment, due to the use of neural network, the accuracy of measurements was improved by about an order of magnitude. Access to the machine code implementing this simulation experiment is provided.