Provision of solution of the problem of autonomous navigation on a long time interval is considered. The main problem when using inertial navigation systems is caused by the accumulation of positioning and angular orientation errors. It is shown that this problem can be solved by combining methods of nonlinear filtering in processing the results of inertial measurements of platform-free inertial navigation systems and methods of reducing the dimensionality of the vector of navigation parameters on trajectory sections described by analytical models. Orthodromic (shortest) and circular intervals, most typical for program trajectories of transport objects – highways, railroads, airlines, etc., are considered as such trajectory sections. For circular intervals, analytical dependencies of the spatial coordinates of strapdown inertial navigation systems were obtained for the first time. These dependencies make it possible to reduce the dimension of the vector of navigation parameters and, as a consequence, to build a model of an autonomous observer of navigation parameters to use equations excluded from the general system of these parameters. It is shown that using stochastic nonlinear filtering methods it is possible to solve the problem of noise-resistant autonomous navigation on trajectory intervals described by analytical models. The proposed approach to solving the problem of autonomous navigation of moving objects makes it possible to significantly reduce computational costs in the practical implementation of algorithms for nonlinear filtering of current navigation parameters in comparison with traditional models of strapdown inertial navigation systems. The effectiveness of the proposed approach is illustrated with a numerical example. The results obtained are useful in developing navigation support for various transport objects moving along program trajectories, for example, aircraft for various purposes, railway, road, river transport, etc.

The issues of improving the metrological characteristics of the phase triangulation method for measuring three-dimensional geometry are considered. In practice, external lighting is usually non-stationary, which affects the stability of measurement results. The paper proposes a method for filtering data received by a photodetector during measurements using the phase triangulation method under non-stationary lighting conditions. The method is based on frequency analysis of received data and filtering according to the criterion of the amplitude of the first harmonic in the frequency decomposition of the signal. The proposed method is implemented in the form of an algorithm for filtering the measured point cloud in a measuring complex that implements the phase triangulation method. The proposed method has been experimentally tested. A comparison was made of the filtering results obtained by the developed method based on frequency analysis of received data and the filtering method based on the analysis of amplitude modulation of the signal intensity recorded by a photodetector. Based on the results of a comparative analysis of the results of filtration by two methods, an increased (more than eight times) efficiency of the proposed filtration method was established. The results of the work will be useful in the field of processing and analysis of experimental results and for the development of optical methods for measuring three-dimensional geometry.

The reconstruction of object images that are located in 3D scene cross-sections using digital holography is described. The potential of generative adversarial networks for reconstructing cross-sections of 3D scenes composed of multiple layers of off-axis objects from holograms is investigated. Such scenes consist of a series of sections with objects that are not aligned with the camera’s axis. Digital holograms were used to reconstruct images of cross-sectional views of 3D scenes. It has been shown that the use of neural networks increases the speed and reconstruction quality, and reduces the image noise. A method for reconstructing images of objects using digital off-axis holograms and a generative adversarial neural network is proposed. The proposed method was tested on both numerically simulated and experimentally captured digital holograms. It was able to successfully reconstruct up to 8 cross-sections of a 3D scene from a single hologram. It was obtained that an average structural similarity index measure was equal to at least 0.73. Based on optically registered holograms, the method allowed us to reconstruct object image cross-sections of a 3D scene with a structural similarity index measure over cross-sections of a 3D scene of equal to 0.83. Therefore, the proposed technique provides the possibility for high-quality object image reconstruction and could be utilized in the analysis of micro- and macroobjects, including medical and biological applications, metrology, characterization of materials, surfaces, and volume media.

Miniature elastic scattering lidars with similar schemes for determining the microstructure of the surface layer of the atmosphere are considered. In the considered microlidar model, it is assumed that in the limiting case there may be no particles in a small probed volume. In this case, the minimum value of the return signal corresponds to molecular scattering. The excess of the signal above this level is associated with the presence of a particle. The molecular component of the backscatter signal is constant and can be compared to a tabulated value of the backscatter coefficient using an optical atmospheric model. This makes it possible to compare the average value of the total backscattering signal from molecules and particles with the overall backscattering coefficient. A scheme similar to a microlidar, but on an enlarged scale – a minilidar – is considered. For both such schemes, the average values of atmospheric backscatter signals are the same. For a minilidar, the return signal is formed by scattering from a layer ranging in size from several meters to several tens of meters. In this case, the probed volume can be determined using perforated screens and reflective spheres. It is shown that the ratio of the probed volumes for the minilidar and microlidar is equal to the similarity coefficient to the fourth power. The considered lidars can be used to determine the concentration of equivalent particles.

A method for passive measurements of water vapor concentration in the atmosphere in the presence of solar radiation has been proposed and tested. The location of the measurements is the northeast of the Moscow region. When processing the results of measurements carried out on a single water absorption line, a coincidence of experimental data and data obtained from direct meteorological measurements with an error of no more than ~7.5 % was revealed. It was also found that on the water absorption line in the region of 1653 nm, the interfering factor is the nearby methane absorption line, which introduces a systematic error in the measurement results, and the results turn out to be underestimated. A possible reason is that the absorption cross section of methane molecules is ~4 orders of magnitude larger than that of water vapor molecules and light radiation is absorbed to a greater extent by methane, reducing the fraction of absorption of water vapor at a wavelength close to the methane absorption line. Compensatory corrections have been introduced to determine the concentration and moisture content in the atmospheric column with an accuracy of several percent at this wavelength. The proposed technique allows both long-term monitoring of concentration and moisture content in the atmosphere and obtaining operational information in real time. The results of the measurements performed are, on average, consistent with the results of measurements obtained using radiometers operating in the ultrahigh frequency range.

Existing methods and devices for measuring temperature are described, and it is noted that resistance thermometers are most widely used as temperature sensors in systems for collecting and monitoring environmental parameters. It is shown that the main source of temperature measurement errors when connecting sensors remotely is the resistance of the connecting lines, determined by their length. The main methods for reducing the measurement error caused by the influence of the resistance of the vehicle connection line on the temperature measurement results are considered. The advantages of two-wire circuits in comparison with three- and four-wire circuits are formulated. As an analogue, a two-wire method of measuring temperature with an integrating converter is considered in detail, implemented on the basis of a device with a built-in microcontroller, and allowing to obtain such advantages as reducing measurement time, detuning from interference and quantization noise and, as a result, reducing the temperature measurement error in comparison with similar two-wire measurement methods. An alternative two-wire method for measuring temperature with automatic adjustment of the parameters of the measurement algorithm is proposed, aimed at increasing the measurement accuracy by weakening the influence of the time constant. The search for the optimal time of the first integration step was carried out. Experimental studies and evaluation calculations were carried out to confirm the effectiveness of the proposed solution. The coefficient of variation when the resistance of the vehicle changes in the range of 1–4 kOhm lies in the range, and the range of change in the relative error of resistance measurement when using auto-tuning within the specified range has decreased by more than 4 times. The results of the experiment allow us to count on the possibility of using the method in control and regulation systems with remote connection of temperature sensors.

Recently, due to increasing environmental requirements, microwave carbonization method has been widely investigated for the production of activated carbon from biomass waste. Microwave carbonization is a more energy efficient and environmentally friendly method compared to traditional carbonization in thermal furnaces, but to date there are still a number of questions about the reproducibility and temperature stability of this process. During microwave irradiation, the temperature of biomass samples changes continuously and complex physical and chemical processes occur in them. For deeper study of these processes and determination of optimal modes of microwave treatment it is necessary to know the temperature dynamics of biomass samples. For this purpose, the method of spectral pyrometry based on the allocation of sections of the spectra of thermal radiation of samples coinciding with the Planck spectrum was used. In the specified spectral sections these samples are gray emitters. The method is effective for an unknown emission coefficient, continuously varying with changes in the microstructure, chemical composition and phase state of the sample. The sample irradiated by microwaves was a sample of orthophosphoric acid-treated cotton down weighing 1 g. The microwave source was a magnetron-type generator with a maximum output power of 600 W and an operating frequency of 2450 MHz. Thermal spectra of the irradiated sample were recorded by small-size spectrometers of visible (350–760 nm) and near-infrared (650–1050 nm) ranges. The time of irradiation of samples by microwaves was varied in the range of 60–180 s. To process the obtained spectra, the program “Spectral Pyrometry” was used, which reads the recorded spectrum, processes it, plots it in the necessary coordinates and calculates the temperature. Analysis of the obtained results revealed different types of thermal radiation spectra of the irradiated sample - spectra similar to spectra of a completely black body, spectra with different temperature zones of the sample, spectra with atomic lines and molecular bands. The results obtained are useful for the study of microwave influence on various objects, research of processes occurring during carbonization of biomass, as well as for the development of more effective modes of production of activated carbons by microwave method.

The park of high-precision measuring instruments of alternating voltage – working standards of the 1st and 2nd category in the frequency range 0.1–30.0 MHz is considered. It is noted that thermoelectric voltage converters, which were developed more than 30 years ago, have exhausted their life and do not meet modern operational requirements, are used as a working standards of the 1st category without alternative. An alternative to sets of thermoelectric converters in the frequency range 0.1–30.0 MHz can be AC voltage calibrators. However, in the specified frequency range, there are no AC voltage calibrators – working standards of the 1st category. For operation in the frequency ranges of 0.1–30.0 MHz and voltages of 1·10^-3–10 V, a high-frequency AC voltage calibrator H5-10 has been developed with characteristics that exceed the requirements for working standards of the 1st category. The principle of construction, characteristics and operational capabilities of the H5-10 calibrator are described. When constructing the calibrator, a method was used to equalize the amplitude of the high-frequency voltage with the known amplitude of the low-frequency sinusoidal voltage by amplitude detection. The high-frequency sinusoidal voltage in the calibrator is generated by a frequency synthesizer using direct digital synthesis and a bandpass filter system. The accuracy and stability of the amplitude of the high-frequency voltage at the output of the calibrator are supported by an automatic control system based on the principle of mutually-inverse conversions using a two-diode integrated assembly of identical Schottky diodes. The low-frequency stable voltage for the reference input of the automatic control system is formed by a low-frequency calibrator with a frequency of 10 kHz. This calibrator generates an alternating voltage in the range of 0.1–10.0 V with a harmonic coefficient of less than 0.01 % and a discreteness of amplitude adjustment of 0.001 %. The low-frequency calibrator is built on multiplying digital-to-analog converters by the method of digital synthesis of a sinusoidal voltage of a stable constant voltage measure of 2.5 V. The nominal output voltages of the calibrator H5-10 in the range of 0.1–10.0 V are reproduced by an automatic control system, and in the range of 1–100 mV by scaling using a voltage divider. The main areas of application of the developed N5-10 calibrator are the verification and calibration of electronic voltmeters, voltage calibrators, multimeters and voltage transducers used as working standards of lower-level categories.

The issues of metrological support for measurements performed using end-to-end technologies, namely the formation of a metrological infrastructure corresponding to the needs of technologies of the sixth technological set-up, are considered. As a result of the research, mechanisms for determining the directions of development of the metrological infrastructure for the introduction and use of innovative technologies that determine the future of the economy of the Russian Federation are proposed. It is noted that the concept of end-to-end technologies appeared in official documents in the Russian Federation in 2017, however, the topic of infrastructure provision of end-to-end technologies has not been widely discussed. This fact, as well as the importance of timely and effective infrastructural support for the new technological policy of the Russian Federation, became one of the reasons for the completed study. The issues of increasing the importance of end-to-end technologies in the development of the economy of the Russian Federation, the use of patterns of development of metrological infrastructure for the timely modernization of the reference base that meets the requirements of innovative technologies of the sixth technological set-up, the issues of directions for the development of metrological infrastructure taking into account the measuring needs of end-to-end technologies were discussed. The positive results of the verification of the patterns of development of the reference base of the measurement uniformity system identified in 2019 by the author of this article are presented and the directions of application of these patterns for metrological support of measurements of end-to-end technologies are shown. As a result of processing official statistical data in the field of metrology for the period 2005–2023 (the period of the origin of the sixth technological set-up), taking into account the patterns of development of the fourth and fifth technological setups, the importance of metrological support for measurements performed using end-to-end technologies is justified. The analysis of the development of the most important components of the metrological infrastructure within the framework of technological structures made it possible to identify the main directions of development of the reference base, the base of measuring equipment, as well as organizations, institutions and enterprises of the metrological infrastructure. The expediency of using the reference base necessary for metrological support of measurements of end-to-end technologies, patterns of development of metrological infrastructure within technological structures as a mechanism for determining the directions of development is substantiated. The results of the performed research can be used in the formation of the next Strategy for ensuring the uniformity of measurements for the period coinciding with the beginning of the dominance of the sixth technological set-up, in the training of personnel in the field of metrology, who will work in the conditions of the new sixth technological set-up, and at enterprises developing innovative products using end-to-end technologies.