The article describes aspects of improving metrological support for measuring units of mass and volume of liquid in the flow, mass and volume flow of liquid in the Russian Federation. We consider fundamentally new design solutions for key modules of the reference unit EU-3 of the state primary special standard for units of mass and volume of liquid in the flow, mass and volume flow of liquid GET 63-2019, based on numerical and physical modeling of hydrodynamic processes under forced pressure flow of the working medium (water) in pipelines with different  flow geometry. The principles of operation of water flow stabilization and control modules are substantiated. Innovative solutions are presented for the design of sensitive elements of the flow switch, the principle of constructing a time diagram, and determining the measurement time interval. Metrological characteristics of the state primary special standard of units of mass and volume of liquid in the flow, mass and volume flow of liquid GET 63-2019 are presented.

A unified fundamental equation of state 2,3,3,3-tetrafl uoropropene (R1234yf) has been developed, a fourth-generation ozone safe refrigerant, and a method for constructing the equation has been proposed. In the gas region, this equation transforms into the virial equation of state, and in the vicinity of the critical point it satisfies the requirements of the modern large-scale theory of critical phenomena and transforms into the Widom scale equation. On the basis of a single fundamental equation of state in accordance with GOST R 8.614-2018, standard reference data (GSSSD 380-2020) on the density, enthalpy, isobaric heat capacity, isochoric heat capacity, entropy and sound velocity of R1234yf in the temperature range from 230 K to 420 K and pressures from 0.1 MPa to 20 MPa. A comparison of the calculated values of equilibrium properties with the most reliable experimental data obtained in the famous of the world, and tabular data obtained on the basis of the known fundamental equations of state R1234yf. Uncertainties of tabulated data for saturated vapor pressure, density, enthalpy, isobaric heat capacity, isochoric heat capacity, entropy and speed of sound of 2,3,3,3-tetrafl uoropropene are estimated – standard relative uncertainties by type A, B, total standard relative and expanded uncertainties. The results obtained in the work show that the proposed unified fundamental equation of state adequately describes the equilibrium properties of R1234yf in the range of state parameters stated above.

Methods of wavelet filtering of noise in signals of measuring transducers using the threshold method of discrete wavelet transform are considered. To study the methods of wavelet filtering of noise, special model signals were used to estimate the filtering errors. A method has been developed for determining the parameters of wavelet filtering of noise with a threshold for all levels of decomposition, which makes it possible to determine the wavelet function, threshold function and filtering threshold of the detailing coefficients of the discrete wavelet decomposition. The influence of the parameters of the noise distribution, the noise level, the number of vanishing moments of the Daubechies wavelet function, the nature of the threshold function and the threshold value on the filtering error caused by the noises of non-stationary measuring signals has been investigated by the method of a computational experiment. The results of the study of six threshold functions are given with the addition of noise to the measuring signal with nonstationary amplitude, frequency and duty cycle of rectangular pulses. The signal of the Doppler sensors is investigated, the wavelet filtering parameters are calculated, which provide the minimum error. The obtained parameters are used to construct graphs of signals before and after filtering directly in the time domain using the inverse wavelet transform.

The problem of improving the accuracy of digital terrain models created for monitoring and diagnostics of the railway track and the surrounding area is considered. A technical solution to this problem is presented, which includes a method for joint aerial photography and laser scanning, as well as a method for digital processing of the obtained data. The relevance of using this solution is due to the existence of zones of weak reception of signals from the global navigation satellite system, since in these zones the accuracy of constructing digital terrain models using currently used diagnostic spatial scanning systems is reduced. The technical solution is based on the method of digital processing of aerial photographs of the railway track. In this case, as elements of external orientation, the threads of the rail track located at a normalized distance from each other are used. The use of this method made it possible to increase the accuracy of determining the flight path of an aircraft over railway tracks and, as a result, the accuracy of calculating the coordinates of points on the earth's surface. As a result, a digital terrain model was created that is suitable for diagnostics and monitoring the condition of the railway trackbed. During simulation modeling, it was found that the application of the proposed method allowed to reduce to 50 % the confi dence interval of the distribution of the error in determining the coordinates of points on the terrain and increase the accuracy of forming a digital terrain model. This promising technical solution for improving the accuracy of digital terrain models for railway track diagnostics is implemented using unmanned aerial vehicles that are part of the mobile diagnostic complex. The advantages of the proposed solution include high efficiency and availability of application.

With regard to the problem of refining the fundamental equations of state of hydrocarbons, the methodological and design features of the experimental measurement of the isobaric heat capacity in the critical region by the method of a flow adiabatic calorimeter are considered. The pressure measurement system has been improved by introducing a differential manometer into the measuring circuit, which made it possible not only to increase the accuracy of pressure determination, but also to implement a universal scheme of calorimetric experiment. The use of a universal scheme of the calorimetric experiment allows one to determine two values of the isobaric heat capacity at pressures that differ by the value of the pressure loss in the calorimeter. Such an approach in the critical region is relevant, since it makes it possible to quite simply and reliably determine the value of the derivative of the heat capacity with respect to pressure, which is used to estimate not only the error in assigning the value of heat capacity to pressure, but also the equilibrium conditions of the experiment in a flow-through calorimeter. The technique of determining and making a correction for the inhomogeneity of the supply wires of the differential thermocouple, for the throttling of the flow of matter in the calorimeter is considered. Correct relations are obtained for determining the average temperature of the measurement experiment for various methods of measuring the temperature and temperature difference in a flow-through calorimeter. The results of experimental measurements of the isobaric heat capacity of n-pentane in the critical region, obtained using the universal scheme of the calorimetric experiment, for n-pentane were measured on an isobar of 3.400 MPa (critical pressure 3.355 MPa), which is the closest to the critical point at practice of flow calorimetry.

The paper considers the problem of accurate calculation of the phase of the radar signal in relation to the receiving phased antenna arrays. Methods for determining the phase difference based on a comparison of the received signal with the local oscillator signal are listed, as well as a method based on the use of a radio-photon analog-to-digital converter  for  the output signal of the receiving phased antenna array. Their disadvantages are indicated. A method and a radio photon device are proposed that are devoid of these disadvantages. The method allows you to calculate the phase difference of the radar signal at the output of the electro-optical modulator and the output signal of the photodetector, taking into account the known values of the amplitudes and phase difference of the microwave signals at the input of the receiving elements of the phased antenna array. The radio-photon device allows you to implement this method and, unlike the known analogues, is based on the use of two parallel-connected electro-optical modulators constructed according to the scheme of the Mach-Zehnder interferometer. It is shown that the proposed radio photon device provides a higher accuracy of determining the phase of the radar signal in comparison with existing analogues. At the end of the work, an analysis of the results of experimental studies using the proposed method and a radio photon device is presented. According to the results of the experiment, it was found that the phase and phase differences vary linearly, and their maximum reaches π. In addition, the square of the amplitude of the optical signal at the input of the photon-electronic unit is proportional to the phase difference and inversely proportional to the ratio of the amplitudes of the output signals of the adjacent receiving elements of the phased antenna arrays.

The issues of optimization of the vehicle anti-lock braking system are considered. To increase the reliability of the system, it is proposed to use a brake distribution system adaptive to the quality of the road surface for a quick stop of the vehicle while maintaining controllability. The system together with sensors angular wheel speed included a microwave Doppler displacement and speed sensor. The use of the specified Doppler sensor made it possible to achieve a more accurate coincidence of the dependence of the braking force on the degree of adhesion of the wheels to the road surface by monitoring the ratio between the angular and linear speeds of movement. In this way, it was possible to minimize the braking distance of the vehicle while maintaining controllability under various driving conditions.

Problems of ensuring the safe operation of an aircraft from the point of view of the fatigue life of its structure are considered. The relevance of the creation and implementation of diagnostic systems for monitoring the technical condition of structures of complex technical objects is shown on the example of a helicopter. An original approach to the creation and implementation of complex systems for diagnostics and monitoring of the technical condition of complex technical objects is presented, combining fi ber-optic measuring  technology and phase-chronometric method. It is shown that the use of monitoring and diagnostic systems ensures the transition to operation based on the actual technical condition. The proposed approach makes it possible to increase the time between overhaul intervals and reduce excess reserves in terms of the reliability factors of structures, which increases the flight performance of aircraft.

The article proposes a new method for increasing the information content of the image by minimizing the errors of the optical system of a large telescope using the redistribution of errors over the image field. Variation of the parameters of the secondary mirror is carried out to solve the optimization problem of uniform distribution of aberrations over the image field of a large telescope using the example of a cryotelescope with a diameter of 12 m in the Zemax-EE package. The results of calculations of optical schemes by the traditional method and by the method of optimization of the errors of the radiation wavefront are presented. The advantages and disadvantages are considered.

This paper presents the results of ultrasonic and eddy-current measurements of the characteristics of austenitic stainless steel AISI 321 under fatigue failure. The effect of the strain amplitude on the intensity of changes in elastic and magnetic properties is studied. The use of a combination of eddy current and ultrasonic measurements makes it possible to assess the state of steel AISI 321 under fatigue failure is shown. The technique for measuring ultrasonic parameters described in this paper allows us to register changes in the structural state of a material under fatigue failure long before the crack is formed. The eddy current method is used to determine the volume fraction of martensite with ferromagnetic properties. An algorithm is proposed for estimating the number of loading cycles and the operating time of metastable austenitic steel AISI 321 based on the data of ultrasonic and eddy current measurements.

As part of the development of monitoring systems for the operation of technical objects, the problem of improving the quality of monitoring systems for the loaded state is considered. Based on the analysis of the mathematical model of the structure and its loading, a methodology for the selection of measuring instruments was developed. The urgency of the problem of calculating substantiation of the choice of key points of the structure is shown, at which it is possible to measure deformations for the subsequent restoration of the existing loads with maximum accuracy. An approach based on the envelope method for determining the rational composition of measuring instruments for restoring the loads acting on the structure is stated.