Need and relevance is shown for precise specific heat measurements of existing and novel synthesized substances and solid materials at low temperatures. Construction, operation principle and the results of metrological investigation are presented for the State primary special Standard of the unit of specifi c heat of solids GET 79-2020. GET 79-2020 is equipped with new improved basic throttle cryostat and cell for heat capacitance measurements providing faster and efficient cooling of measured samples and suppression of parasitic heat fluxes. The ranges of reproduction of the unit of specific heat of solids in GET 79-2020 is 0,03–718 J/(kg·К), and the temperature range is 2–300 K. Method of heat capacitance measurements is described with application of developed cell. Metrological characteristics of GET 79-2020 are investigated. An uncertainty budget is calculated for reproduction of the unit of specific heat. The obtained results significantly expand the temperature range of measurements and the park of working standards for heat capacity measuring instruments verified at GET 79-2020.

The central question of the cosmic shock in the series of articles “Cosmological Distance Scale” is considered: do the data for parametric identification of the Friedman-Robertson-Walker model in the form of a dependence of the photometric distance on the redshift of type Ia supernovae used in the work of the High-Z SN Search Team and Supernovae Cosmology Project allow us to consider the acceleration of the expansion of the Universe as the most plausible hypothesis on the criterion of the minimum error of inadequacy. The previously discovered discrepancies (changes in the structure and parameters of the systematic component of the model) and rank inversions of photometric distances of supernovae SN Ia for the systematic component of this model are analyzed. It is shown that the cause of these metric violations is the isotropy of the Friedman-Robertson-Walker model. In the anisotropic model of the cosmological distance scale, the disjunctions and rank inversions are associated with the orientation of the gravitational dipoles of the heterogeneity of the large-scale structure of the Universe. These dipoles represent diametrically opposite pairs of “super cluster galaxies – giant void” on the celestial sphere. Due to the size of only the super-void in the constellation Eridanus, comparable to the size of the observable part of the Universe, a colossal imbalance of the gravitational action of a massive super cluster of galaxies is created. This leads to disturbances in the form of disorders and rank inversions in isotropic Friedman-Robertson-Walker type models.

Methods for processing measurement information collected over the past 30 years by altimetry spacecraft with various measurement technologies and orbit characteristics are systematized and described. The description and classification of measurement information files is given. Based on the removal-recovery method, a software package for determining the characteristics of the gravitational field and the figure of the Earth by satellite altimetry has been developed. On the example of a geologically complex and seismically active region (the Caribbean Sea), a model of the gravity field (gravity anomalies) was constructed and its accuracy characteristics were evaluated. The calculated standard deviation of gravity anomalies from the data of the EGM2008 global model does not exceed 4 mGal in the open sea and 14 mGal in the coastal zone, which corresponds to the international level. At the moment, a digital interactive gravity model of the Global Ocean is used to solve applied problems of geophysics and geology, in particular, to forecast oil and gas fields.

The possibility of improving technical means that make it possible to introduce phase shifts into light beams in the interferometer paths is considered. An optical-mechanical phase modulator in the form of a plane-parallel glass plate rotated around an axis lying in its plane was adopted as the initial version of these technical means. A differential method is proposed for the formation of relative phase shifts between beams in a two-arm interferometer. A variant of the modulator has been developed in the form of a pair of rigidly interconnected plates, the planes of which are initially rotated at a given angle. In this case, each of the parallel light beams in the interferometer passes through its own plate. It is shown that in this case a practically linear relationship is provided between the generated relative phase shift and the total angle of rotation of the plates. A variant of using a single plate as a modulator under the established conditions for the incidence of two beams propagating in different arms of the interferometer is considered. The operability of the proposed differential method for controlling the phase shift between light beams is confi rmed by the data of a test experiment. The results obtained will be useful in the development of special tools based on the method of digital speckle pattern interferometry for measurements of the displacement fields of deformable bodies

Goniometric methods of measuring the refractive index of optically transparent materials based on the refraction of light by a triangular prism are considered. Modified method of the minimum deviation and 3 modified constant deviation methods are considered, which allows determining the refractive index of triangular prisms with unknown apex angles. According to modified methods, the angles of light deviation by a prism are measured with goniometer, and the refractive index of the material and the prism angles are determined from solving the systems of equations. Thus, there is no need for preliminary measurement of the prism angles, which requires the use of special autocollimation goniometers. In addition, the modified methods do not use radiation reflected from the faces of the prism, which makes it possible to extend the spectral range of measurement of the refractive index to the infrared and ultraviolet regions. A comparative accuracy analysis of the considered methods for a prism with a refractive index of 1.5 and an angle of 60° as example is carried out. It is shown that the modified methods can be used for high-precision measurements of the refractive index in cases if the apex angles of the prism are unknown or their measurement is associated with technical difficulties. The considered methods can be used to measure the refractive index of triangular prisms made of optically transparent materials, as well as liquids poured into hollow prisms with plane-parallel transparent windows. The practical implementation of such a methods can be useful in the optical, chemical and food industries to control the composition and properties of optically transparent substances.

The issues of developing simple and affordable methods for controlling the authenticity and quality of alcoholic beverages based on Raman spectroscopy are considered. The most important characteristics of brandy and cognac products – geographical origin and aging period, which largely determine the cost of production and by which it is often falsified, are studied. The advantages of the investigated method include ease of sample preparation up to its complete absence, high selectivity, rapidity and simplicity of analysis, the possibility of developing compact instruments that allow analysis to be carried out directly on the sampling spot. The Raman spectra of 42 different samples of brandy and cognac products, differing in geographical origin and aging period, were measured. It is shown that the fragments of the spectra measured in the range of Raman shifts from 800 cm^–1 to 3000 cm^–1 are the most informative for solving the tasks set. From the studied samples, training and test sets were formed. For data processing, machine learning models trained using the extreme gradient boosting algorithm were used. The correctness of recognition by geographical origin and aging period for undiluted samples of the test set, the spectra of which were not used when training the model, was 100 %. The results of the study can be used to develope compact devices for express control of the authenticity of alcoholic products and determine their characteristics using Raman spectra and their further processing by machine learning methods.

The issues of increasing the accuracy of volume sensors and the angular position of the liquid mirror in the fuel tanks of upper stages of spacecraft are covered. It is shown that the existing sensors of this type do not always meet the stringent requirements for their accuracy and reliability characteristics, especially under conditions of an indefi nite position of the liquid mirror. The principle of construction and design of a sensor for tanks with axial symmetry (spherical, cylindrical, lenticular, etc.) is proposed, which provides simultaneous measurement of the amount and angular position of the liquid mirror with high accuracy under the specifi ed conditions. This sensor consists of one linear and several ring sensing elements immersed in liquid and designed for the primary conversion of the immersion depth into an informative signal. The linear sensing element is installed along an axis passing through the center of the tank and the intake hole, and the ring elements are installed in a plane perpendicular to this axis, at a distance from each other determined by a given error. The operation of linear and ring elements can be based on a thermoresistive or capacitive principle. In the latter case, the sensitive elements may take the form of resonant circuits consisting of one linear and several ring capacitances, to which inductances are connected. Algorithms have been developed for converting the resonant frequencies of at least two sensitive elements into the desired parameters: the volume and angular position of the liquid in the tank. The estimation of the components of the total error of the sensor, due to various factors: the discreteness of the sensor design, the spread of the geometric dimensions of the tank and sensitive elements, as well as the own errors of the sensitive elements, was carried out. It is shown that the main factor limiting the accuracy of the sensors is the reduced errors of the sensitive elements: with the reduced error of these elements of 10^–3, the similar errors of the sensor are no more than 2.2∙10^–2 in angle and 3.2∙10^–3 in volume. The proposed sensor can be used to measure the specifi ed parameters in objects characterized by an indefi nite position in space (spacecraft, sea vessels during rolling or heel).

The use of circular contour sensors on printed circuit boards placed between contacting spheres with radius R in the magnetized chain of balls makes it possible to measure magnetic microflows in the chain along its cores of different radius r_c. Thus, it becomes possible to obtain information about the magnetic properties of not only the cores of the chain themselves, but also its pipe quasi-functional layers limited by adjacent sensors. It is the purpose of the work. According to the magnetic flux measured with the help of well-recommended contour sensors (eight: from r_c/R from 0.2 to 0.9) at magnetizing fi eld intensity in the range of 10–55 kA/m, magnetic flux is established along seven pipe-layers of relative radius r_p/R (from 0.25 to 0.85). The values χ_p of their magnetic susceptibility were found, as the r_p/R values increase χ_p-values decrease according to the inverse power dependence with a power degree equals 2.4. The values of the demagnetizing factor are set and functionally approximated for pipe-layers in relatively short chains of different lengths (with a number of spheres from 2 to 8). The obtained information expands idea about magnetization a chain of granules as the basic element of the granular medium. This information is useful in detailing the characteristics of such heterogeneous media used to solve scientific and practical problems, in particular, to clarify the conditions for building zones that are responsible for the magnetic capture of magnetoactive particles between granules of working elements (matrix type) of polygradient magnetic separators and analyzers.

The current regulatory documents for measures in the form of standard samples CO-2, CO-1 used in ultrasonic non-destructive testing are analyzed. The normalized metrological characteristics of measures are considered. It is shown that the normalized metrological characteristics do not ensure the reliability of the control in the proper volume. Differences in the normalized characteristics of measures of the same type produced by different organizations and shortcomings in the normalization of acoustic characteristics are noted, leading to different values of instrument parameters on measures of the same type and a significant error in the evaluation of control results. The necessity of normalizing the ultrasound velocity for the types of waves actually used in the measures and reducing the permissible error of measuring the velocity in the measures to ±(0.2–0.5) % is shown. It is noted that the attenuation of ultrasound in the measures is normalized only for a longitudinal wave at one frequency of 2.5 MHz and does not provide the claimed error of ± 1 dB when adjusting to the sensitivity of the devices and assessing the size of the detected defect. It is proposed to determine the attenuation of ultrasound in measures by comparing the amplitudes of ultrasonic echo signals in these measures with the amplitude of the ultrasonic echo signal in the initial measure. At the same time, the initial measure should have a simple geometric shape that allows it to be certified according to the absolute value of the attenuation coefficient. It is noted that the current State verification scheme for measuring the propagation velocities and attenuation coefficient of ultrasonic waves in solid media requires improvement, since it does not provide for the transfer of a unit of attenuation coefficient for shear waves and it does not fully take into account the real state of affairs with the measuring instruments already used in practice. To ensure the comparability and reliability of measurement results with the help of measures in full, it is proposed to develop a unified regulatory document for the general requirements for the standardized metrological characteristics of measures, methods of their measurement and a local verification scheme for transmitting units of speed and attenuation of ultrasound.

The task of measuring the power spectral density of a speech signal in the regime of a sliding observation window is considered. A parametric approach to solving this task using an autoregressive data model is studied. The problem of optimizing the order of an autoregressive model under conditions of small samples is studied. The problem is proposed to be solved using a hybrid method of spectral analysis based on sequential enumeration of a fi nite number of alternatives. The optimization criterion is formulated in terms of the inverse problem: from a speech signal to a voice source. It uses the scaleinvariant measure of the spectral distance as the objective function, and the Schuster periodogram as the reference sample. The effectiveness of the hybrid method has been experimentally evaluated on the basis of author's software. It is shown that with the duration of the observation window of no more than 10 ms, the use of the hybrid method increases the accuracy of spectral analysis by more than 30 % compared to the well-known Berg method, the order of which is established according to the Akaike information criterion.

Initiated by COOMET TC 1.2 “Acoustics, Ultrasound, Vibration” bilateral pilot comparisons of amplitude-phase calibrations of hydrophones in the frequency range 10–500 kHz COOMET 786/RU-a/19 between the Hangzhou Research Institute of Applied Acoustics (HAARI) and the Russian Metrological Institute of Technical Physics and Radio Engineering (pilot laboratory) are described. Characteristics of reference hydrophones, information about standard facilities and methods of calibration, results of calibrations, and estimates of reference levels of comparisons are given. The results of comparisons are discussed. The problems that infl uenced the results of comparisons are mentioned. The correctness of the measurement methods used by the participants of the comparisons, including the method of calculating the frequency dependence of the argument of hydrophone complex sensitivity from the experimental frequency dependence of the modulus of its sensitivity, was confirmed. The results of the pilot comparisons were found to be satisfactory. When discussing the results of comparisons at the COOMET TC 1.2 meeting, it was proposed to conduct additional comparisons of the results of amplitude-phase calibrations in an expanded composition of participants. The results obtained make it possible to verify the correctness of the adopted new technical solutions, to work out methods for performing measurements and post-processing of the obtained data, to identify and numerically evaluate sources of uncertainty, and also to establish previously unaccounted sources of uncertainty when improving primary standards.