Measurement Techniques

Vinge, M. A.; Morozov, S. A.

doi: 10.1007/s11018-023-02142-8pmid: N/A

This article describes methods for expanding the numbers and ranges of reproducible values and improving the functionality of the state primary standard of units of relative humidity of gases, molar (volume) fraction of moisture, and dew/frost point temperature (DPT) GET 151-2014. As a result of the studies, the state primary standard of the units of relative humidity of gases, molar (volume) fraction of moisture, DPT, and hydrocarbon condensation temperature (HCT) GET 151-2020 was developed and approved, which included a set of reference generators that reproduce the DPT and condensation temperature of hydrocarbons at high pressures of the working gas. The work presents the description of GET 151-2020 and the complex of reference generators included in it, which implement the reproduction of units of the DPT and HCT, taking into account the influencing factors on the working gas pressure. The metrological characteristics of GET 151-2020 are analyzed. A budget of the measurement uncertainty is compiled when reproducing the DPT and HCT. The state verification scheme of tools for the measurement of gas humidity and HCT was developed and approved. Topical issues of ensuring the uniformity of measurements in the field of hygrometry are resolved. The tasks of the metrological support of means for measuring the dew point temperature and condensation temperature of hydrocarbon gases at high pressures of the working gas are implemented. The results obtained can be useful in creating an experimental base for studying the physical properties of technical and natural gases and approving state reference data in a wide range of pressures and temperatures of the working gas.

Levin, S. F.

doi: 10.1007/s11018-023-02143-7pmid: N/A

In the latter half of the 20th century, data that indicated anomalies of Hubble's redshift law were obtained, and a hypothesis on the origin of quasars as ejections from galaxies with active nuclei was also suggested. By the end of the 20th century, the redshift dipole anisotropy and anomalies of Hubble parameter estimates were discovered in the Local Group of galaxies. The increasing discrepancy of these estimates for Type Ia supernovae (SN Ia) caused a discussion on the crisis in cosmology, initiated by Wendy Freedman and Adam Riess. Such a discrepancy is relative to the estimates of the Hubble parameter based on the measurements of microwave background radiation when interpreting measurement data within various cosmological models and the redshift anisotropy in 2016. The problem of identifying the scale of cosmological distances is considered a calibration problem. As a result of its solution, the redshift anisotropy dipole of SN Ia was revealed as reference points of the photometric distance scale. The dipole has a maximum value in the north galactic pole region and a minimum value in the south galactic pole region. The opposite orientation of the redshift anisotropy dipole for quasars has become a new aspect of the problems of the cosmological distance scale.

Volosnikov, A. S.

doi: 10.1007/s11018-023-02144-6pmid: N/A

This article reviews the publications on the theory of dynamic measurements. The problem of minimizing the dynamic measurement error, whose components are due to the dynamic properties (inertia) of the sensor and additive noise at its output, is discussed. To solve this problem, a method is proposed for minimizing the dynamic measurement error as a result of the simultaneous correction of the specified components, and the structure of the measurement system is developed. The measurement system evaluates the dynamic measurement error and reduces it through a simultaneous restoration and filtering of the input measured signal of the sensor. The structure of a special filter with the preliminary correction of the transfer function of the sensor for the further processing of the measured signal is proposed. The processing of the dynamic measurement error consists of the iterative application of a finite impulse restoring filter (or nonrecursive filter) and estimation of the dynamic error. The computer simulation of the developed measurement system was performed for the second-order sensor. The optimal (in terms of the minimum estimate of the dynamic error) values of the order of the restoring filter for the input signals of various types in the presence of an additive Gaussian noise at the sensor output were obtained. The reduction of the dynamic error with the use of the developed measurement system is demonstrated. The obtained results can be used in measuring the parameters of rapidly varying processes when the dynamic component of the error is dominant, which is due to the dynamic properties (inertia) of the sensor and additive noise at its output.

Vishnyakov, G. N.; Minaev, V. L.; Bochkareva, S. S.

doi: 10.1007/s11018-023-02145-5pmid: N/A

The issues of metrological support of the instruments for measuring a two-dimensional spatial distribution (profile) of a unit of refractive index for solids are considered. A reference system has been developed, which is included into the State Primary Refractive Index Standard (GET 138-2021). The composition, principle of operation, and main metrological characteristics of the reference system, based on a digital interferometer for measuring a two-dimensional spatial distribution (profile) of the refractive index for thin sections of the preforms of graded-index glass fibers, are presented. The reference system according to GET 138-2021 provides the uniformity of measurements for the instruments used to measure the refractive index profile—so-called optical analyzers of preforms of the graded-index and optical glass fibers. The results of experimental studies of GET 138-2021 in terms of reproducing a two-dimensional spatial distribution of the refractive index unit are presented.

Arumov, G. P.; Bukharin, A. V.

doi: 10.1007/s11018-023-02146-4pmid: N/A

An important problem of remote monitoring of scattering particles in the lower atmosphere is the development of methods for obtaining information about the microstructure of the scattering layer based on the measured backscattered signal. The main parameters of the microstructure of the surface layer of the atmosphere (particle concentration and cross-sectional area) and main measured quantities during LiDAR sounding (backscattering and extinction coefficients) were considered. During a single-frequency LiDAR sounding, these coefficients can be associated with an equivalent scattering medium consisting of monodisperse particles. This makes it possible to interpret the backscattering and extinction coefficients based on the microstructure of an equivalent medium. The quantity directly related to the transverse particle size is the angular size of the halo around the beam propagating in the scattering medium. An example of a two-position sounding scheme was used to consider the methods for measuring the angular size of the halo around a beam that has passed through a scattering screen. The scattering screen represents an opaque plane with apertures, the projections of which are the images of the particles. It is shown that doubling of the angular size of the beam passing through the screen results in the optimized angular size measurement scheme. This can be achieved either by choosing a linear magnification, according to which the images of the particles on the screen are created, or by moving the screen along the sounding line. The implementation of these methods makes it possible to describe the polydisperse and nonspherical particles contained in the surface layer of the atmosphere by using the cross section of the equivalent particles. Thus, it becomes possible to use the remote methods to monitor the surface layer of the atmosphere.

Nikolaev, Yu.L.; Samorukov, A. A.; Borisenko, A. A.

doi: 10.1007/s11018-023-02147-3pmid: N/A

Methods are described for estimating the sensitivity characteristics of a vibration induction transducer designed to monitor the discontinuity of the surface of objects when they are magnetized by an applied constant field. Based on analysis of the mathematical model of the output signal of the vibration-induction transducer, analytical expressions are obtained for the conversion factors of the rate of change in the magnetic field intensity and acceleration along the coordinate of the vibration displacement of the transducer in the EMF induction coil. Methods of experimental estimation of the conversion factors are given, and the high convergence of calculated and experimental estimates is shown. Based on the formulated conditions for the detection of magnetic field anomalies arising on the defective surface areas and the known values of the conversion factors, calculated ratios were derived to estimate the sensitivity thresholds of the transducer according to the orthogonal components of the magnetic field intensity distribution. As a result of experimental verification, the adequacy of the calculated and experimental estimates of the sensitivity thresholds was confirmed. Recommendations are given for the application of computational and experimental methods for assessing the sensitivity characteristics of a vibration induction transducer.

Boykov, I. V.; Pivkina, A. A.

doi: 10.1007/s11018-023-02148-2pmid: N/A

A two-stage approximate method for recovering the phase of the signal spectrum from the amplitude of the spectrum is proposed. In the first stage, the signal is recovered by a numerical method (in the one-dimensional and two-dimensional cases) from the known modulus of the spectrum; in the second stage, the spectrum of the recovered signal is determined and the phase of the spectrum is calculated. signal recovery from a known modulus of the spectrum is modeled by a nonlinear Fredholm equation of the first kind, which is solved using the spline-collocation method with splines of zero and first orders and a generalization of the continuous method for solving nonlinear operator equations. Model examples of the recovery of one-dimensional and two-dimensional signals are given. The accuracy of signal recovery for various perturbations in the input signals and in computational frameworks has been studied. The absolute and relative values of spikes at the leading and trailing edges of the signals are estimated. methods for suppressing the Gibbs effect are considered. The proposed method can be used in optics, astrophysics, biology, and medicine.

Khatamtaev, B. I.; Shcherblyuk, N. G.

doi: 10.1007/s11018-023-02149-1pmid: N/A

Methods for increasing the accuracy of hydrophone phase calibration are considered. It is shown that when calibrating a hydrophone, the reference center, for example, the geometric center of the contour of the active element of the hydrophone, can be displaced relative to the acoustic center of the active element due to the uneven thickness of the waterproofing coating of the element. A method is proposed for determining the position of the acoustic center of a hydrophone relative to a selected reference center. The scheme of the experiment to determine the position (displacement) of the acoustic center of a hydrophone relative to the geometric center of the contour of the active element is described. The results of experiments for different types of hydrophones are presented and the sources of measurement uncertainty are analyzed. It is shown that taking into account the displacement of the acoustic center makes it possible to improve the accuracy of the phase calibration of hydrophones. The proposed method can be used in the field of hydroacoustic measurements of the sensitivity of sound pressure receivers.

Savchenko, V. V.

doi: 10.1007/s11018-023-02150-8pmid: N/A

The problem of determining the accuracy of an autoregressive model of a speech signal is considered, and a method for measuring the accuracy index in the sliding observation window mode is proposed. As an indicator of accuracy, we used a modified value of the COSH-distance (hyperbolic cosine) of the autoregressive model relative to the eponymous (single phoneme) Schuster periodogram as a reference spectral sample. To study the possibilities of the proposed method, a full-scale experiment was set up and carried out, in which the object of study was a set of autoregressive models of different orders. These models were obtained by Berg’s method for the vowel speech sounds of a test speaker. According to the results of the performed measurements for each vowel, the optimal values of the autoregressive order and the corresponding optimal autoregressive model were found. It is shown that this optimization made it possible to increase the accuracy of the autoregressive model of the speech signal by more than 60%, depending on the sound of the test speaker's speech and the characteristics of his vocal tract. The results obtained are intended for use in automatic processing and digital speech transmission systems with radical data compression based on linear prediction coefficients.

Krylov, A. I.; Budko, A. G.; Mikheeva, A. Yu.; Tkachenko, I. Yu.; Nezhikhovskiy, G. R.

doi: 10.1007/s11018-023-02151-7pmid: N/A

The article considers the problems of environmental pollution by phthalates and the impact of phthalates on human health. The article describes the process of developing a reference method of measurements (RMM VNIIM-243-01-2019) of the mass fraction of esters of ortho-phthalic acid (dimethyl phthalate, diethyl phthalate, di(n-butyl) phthalate, benzylbutyl phthalate, di(2-ethylhexyl) phthalate and di(n-octyl) phthalate) in polymer matrices based on polyvinyl chloride by isotope dilution gas chromatography/mass spectrometry. The stages of the measurement procedure and ways of optimizing them in order to improve the measurement results accuracy are discussed. The sources of uncertainty are studied and the contributions of all components to the total standard uncertainty of the RMM measurement results are minimized. The metrological characteristics of RMM have been established: the measurement range is 10–5000 mg/kg; the standard deviations under conditions of repeatability and intermediate precision are 2 and 3%, respectively; the relative extended uncertainty is 6–8%. The method is intended to establish the metrological characteristics of reference materials of matrices, examine the correctness of the measurement results obtained using other techniques (methods) for measuring similar quantities, and perform measurements for arbitration purposes. The results of key international comparisons CCQM-K133 “Phthalate esters in Polyvinyl Chloride (PVC)” are presented as an objective confirmation of compliance with the RMM.