The description of the State Primary Standard of optical density unit GET 206-2016 is given. The principle of operation of the standard, based on filtering the luminous flux of transmitted and reflected light, is described. The composition of the standard and its metrological characteristics are presented. Data on the study of the geometric and spectral characteristics of the standard are presented. Currently, GET 206-2016 allows solving the problems of metrological support of optical transmittance density measuring instruments (radiographic non-destructive quality control of materials in various industries) and optical reflection density measuring instruments (printing, applications of energy-saving and graphic technologies).

Description and metrological characteristics are presented of upgraded in 2021 equipment of National primary state standard of temperature on the temperature range from 0.3 K to 273.16 K GET 35-2021. GET 35-2021 allow to to the reproduce and disseminate the unit of temperature according to its definition accepted on 26th CGPM in 2018. Three installations of acoustic gas thermometry developed in 2012–2019 have been introduced in the National primary state standard covering ranges 79–273.16 K, 4.2–80 K, 268.16–273.16 K. The equipment for reproduction of fixed points of of International Temperature scale ITS-90 has been upgraded for uncertainty reduction. Uncertainty of reproduction of thermodynamic temperature and temperature according to ITS-90 have been calculated on the basis of investigations of upgraded equipment.

The problem of analytical representation of hydrophone complex frequency response based on a model consisting of an advance line and a minimum-phase part, which describing the effect of sound diffraction and resonance properties of an active element, is considered. Algorithms are proposed for approximating the hydrophone complex frequency response by a fractional-rational function of the complex variable according to the data of the hydrophone amplitude-frequency and/or phasefrequency responses. Examples of the application of these algorithms for processing experimental frequency characteristics of hydrophones are given.

The determination and confi rmation of the calibration measurements capabilities of national metrological institutes is necessary for the verification of the estimated metrological characteristics of the primary standard machines of these institutes. The passage of national primary standards through the comparison procedure encourages a deep and detailed study of the factors that affect the uncertainty of measurements. Adding the calibration capabilities of metrological institutes to the database of the International Committee of Weights and Measures (hereinafter referred to as the CIPM) allows for calibration of measuring instruments, which is recognized by the entire world community. The article presents the results of comparisons of national primary hardness standards on the Vickers scale and on the Brinell scale between the metrological institutes of the countries that are members of the Organization of Euro-Asian Cooperation of state Metrological Institutions (СOOMET). The comparisons were carried out within the framework of the technical committee on Mass and Related quantities TC 1.6, subject code – 341/RU/05. The article describes the procedure for conducting regional key and additional comparisons of national primary hardness standards on the Brinell and Vickers scales. Based on the results of the comparisons, recommendations are given to the laboratories that participated in the comparisons about the extended measurement uncertainties that they can enter into the database of the International Committee of Weights and Measures.

The multiplication of national units transfer instruments with established values of metrological traceability in international organisations is one of the most actual development directions for a large number of countries, inasmuch as this direction contributes to the solution of a global problem of measurement results comparability which were received for various objects in different times in different parts of the world as well as indicates the high quality of measuring capabilities of an organisation or a country. The paper contains issues of establishment of metrological traceability of results of physicochemical measurements. The international practice on traceability establishment of reference materials’ certified values is described in the work. The authors also provided a brief overview of internationally accepted fundamental concepts of reference materials metrological traceability demonstration.

The concept of reference materials metrological traceability establishment within the framework of Euro-Asian Cooperation of National Metrological Institutions (COOMET) Technical Committee 1.12 “Reference Materials” (TC 1.12) is overviewed. Particular cases of COOMET Reference Materials development are provided. The authors considered approaches to demonstrate a metrological traceability of reference materials with different types of their characterisation, e. g., appliance of national measurement standards, or performance of interlaboratory comparison testing, or usage of primary reference measurement procedure for reference materials characterisation if a state measurement standard for units is absent.

The results of additional bilateral comparison of initial standards of the impulse electrical voltage unit were considered. As a result of comparison there were confirmed announced uncertainties and calibration and measurement capabilities of the participants of comparison. The comparison was carried out under guidance of COOMET (project 710/RU-a/16) оn the initiative of national metrology institutes (NMI): VNIIFTRI (Russia) and BelGIM (Republic of Belarus). The comparison involved national standards: the State primary standard unit of the impulse electrical voltage unit (GET 182-2010, VNIIFTRI) and the original standard of the impulse electrical voltage unit BelGIM. Step pulse generator TMG030010SN11-M1 was used as a traveling standard. The values of the impulse electrical voltage, reproduced by means of traveling standard, were measured by national standards. The purpose of comparison was to confirm confidence in the measurement results and calibration certificates, issued by the NMI in the field of impulse electrical voltage measurements. In the comparison VNIIFTRI acted as a pilot laboratory. Measurements of impulse electrical voltage by means of traveling standard were carried out in the following order: first – measurements of impulse electrical voltage on GET 182-2010, then – on the original standard of BelGIM and finally – again on GET 182-2010. Processing of the results of comparison according to χ2(i) criterion showed that χ2(i) criterion values (calculated on the basis of the measurement results) doesn’t exceed a critical value χ2, that is the objective confirmation of announced uncertainties, declared by the participants of comparison.

A reaction-regeneration system is described, which is a hardware part of industrial production and is characterized by an exceptional feature – pronounced nonlinearity in the form of a plurality of stationary solutions of model differential equations. This feature forces one to resort to engineering solutions that are alternative to direct measurements. The problem of indirect estimation of the components of the state vector of the reaction-regeneration system is considered. The incorrectness of the indirect assessment of the state of such objects on the basis of the theory of Kalman filters is shown. The incorrectness is due to the ambiguity of the mapping of the state space into the space of vectors tangent to the trajectories. An approach based on synchronous simulation in dynamics is proposed, which consists in comparing two evolutions “object – model” with minimization of the mismatch. A technique based on the inclusion of the second derivatives of the state variables into the mismatch function is presented. The methodology of the sensitivity of indirect estimation systems based on maximizing the similarity of the compared evolutions “object – model” in the regime of strict synchronization with respect to external disturbances and control levers is considered. It is shown that the accuracy of the indirect estimation of physically unmeasurable coordinates is largely determined by the mathematical aspects of minimizing the mismatch function, which, due to the multiplicity of solutions to model equations, has a complex structure of the response surface.

The problem of physical implementation of atomic timescales maximally adjusted to the national timescale UTC(SU) for working and secondary standards is considered. Results of analysis of stationary process of hydrogen maser timescale automatic steering to UTC(SU) using common view technique based on the signals of global navigational systems are presented. Calculation of Kalman filter and linear quadratic regulator parameters is described. Theoretical and experimental estimations of automatic steering quality characteristics are compared and discussed. The results obtained can be used to improve the accuracy of timescales on working and secondary standards.

The problem of the synchronization of onboard clocks of navigation satellites has considered from a relativistic point of view using the concept of “coordinate simultaneity”. This concept allows an unambiguous interpretation of the synchronization results within the framework of general relativity. The algorithm of intersatellite measurements processing has formulated in terms of a proper time of a space vehicle and the coordinate time of a reference frame. Rules of transformation between coordinate and proper time scales have indicated. An analytical expression has obtained for the periodic relativistic correction to the estimated value of the relative clock drift. This correction has expressed in terms of the coordinate time of a ground observer. The value of this correction exceeds the acceptable synchronization error and should be taken into account for the inter-satellite measurements processing. The error of the relativistic correction determination has calculated. This error provides an upper limit for the period of uploading of ephemeris data on the board of the space vehicle.

The magnetic moment of the ship is measured to control its protection from magnetic mines and to control the stealth by the magnetic field. A modification of the measurement method using a three-component differential magnetometer is considered. Using computer simulation, the errors of the new method are compared with those of the known analogues and its advantage in accuracy is established (almost by an order of magnitude). It is shown that the new method can also be used for magnetic models of ships and standard samples of magnetic materials to determine their components of the hysteresis loops by magnetization.