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Abstract An important aspect of Space Situational Awareness is to estimate the intent of objects in space. This paper discusses how discriminating features can be obtained from Inverse Synthetic Aperture Radar images of such objects and how these discriminators can be used to recognise the objects or to estimate their intent. If the object is, for example, a satellite of a known type, the scheme proposed is able to recognise it. The ability of the scheme to detect damage to the object is also discussed. The focus is on imagery obtained in the sub‐terahertz band (typically 300 GHz) because of the greater imaging capability given by the diffuse scattering which is observed at these frequencies. The paper also discusses the importance of being able to use images obtained by electromagnetic simulation to be able to train the subsystem which recognises features of the objects and describes a practical scheme for creating these simulations for large objects at these very short wavelengths.

A model-based technique to estimate the accuracy of the ionospheric total electron content (TEC) based on the data from spaced receivers of low Earth orbit satellite signals has been suggested. That allows us to estimate the total electron content errors for both quiet ionosphere conditions and under the presence of a plasma ring. To estimate the error, the dynamic model of the electron concentration of the Earth's ionosphere has been used. For the selected input parameters (day of the year, time of day, etc.), a model two-dimensional electron density distribution has been calculated using this model. When calculating this two-dimensional distribution of the electron density, changes have been made that transformed it into a distribution that most closely matches the real ionosphere, for example, the presence of a plasma ring, a trough, etc. Using the obtained distribution, some model quantities (differential phase and total electron content) have been calculated. Then they are used for model estimation of errors in the calculation of the TEC by the spaced reception method. For quite conditions in the ionosphere, the relative error of determining the initial phase constant does not exceed 3 %, and in the case of the plasma ring – 13 %. For the vertical total electron content, the relative error in quite conditions does not exceed 7 %, and in the case of a plasma ring – 60 %. Large values of the relative error are in areas of sharp change of the vertical total electron content.

Abstract Millimetre‐wave frequency‐modulated continuous wave (FMCW) radars are at present widely deployed in the autonomous vehicles. The growing usage of such sensors, as a vital part of a robust future autonomous sensing system, sees the potential for significant increase in mutual interference and adverse effects on sensor operation. Effective target detection in the background of interference requires knowledge of the interference statistics. In the case that such statistics are found to be similar to that of additive white Gaussian noise (AWGN), then classical well‐established detection techniques can be applied. Conversely, if statistics are found to be different, traditional techniques (matched filtering) will not be optimal. Here, a statistical analysis of mutual interference within an FMCW victim radar is presented. The majority of cases show a low correlation between the interference pulses received at the victim radar, with close to a Gaussian distribution. Some specific cases show a high correlation between the interference pulses in the victim radar chirps with a sinusoidal‐like distribution, which degrades the victim radar’s detection performance. The presented analysis is validated by experimental data for various interference cases.

Abstract Mutual interference in automotive radar is expected to become a major issue owing to the rapid increase in the number of vehicles on the road equipped with radar. The phenomenology of interference in frequency modulated continuous wave radar is presented. Interference is empirically analysed at every signal processing stage in the victim radar by means of experimentally verified simulation modelling. Knowledge of how interference manifests in different domains provides a useful tool to develop algorithms for interference detection, mitigation and/or avoidance. The receiver's filter response is analysed to minimise the interference duration and increase the effectiveness of time‐domain mitigation techniques. A innovative method of interference parameter extraction by using spectrograms is also introduced.

This is the case report of successful treatment of the patient with acute stroke and tandem lesion of the intra- and extracranial divisions of the internal carotid artery.

An important aspect of Space Situational Awareness is to estimate the intent of objects in space. This paper discusses how discriminating features can be obtained from Inverse Synthetic Aperture Radar images of such objects and how these discriminators can be used to recognise the objects or to estimate their intent. If the object is, for example, a satellite of a known type, the scheme proposed is able to recognise it. The ability of the scheme to detect damage to the object is also discussed. The focus is on imagery obtained in the sub‐terahertz band (typically 300 GHz) because of the greater imaging capability given by the diffuse scattering which is observed at these frequencies. The paper also discusses the importance of being able to use images obtained by electromagnetic simulation to be able to train the subsystem which recognises features of the objects and describes a practical scheme for creating these simulations for large objects at these very short wavelengths. [ABSTRACT FROM AUTHOR]

The objective of the study is to evaluate the results and compare the methods of different variants of surgical treatment for the occlusive-stenotic lesion in extracranial parts of the carotid arteries.Material and methods. Comparative analysis of immediate and remote results, and evaluation of patency after 450 carotid endarterectomy performed by classic and eversion technique.Results. A significant advantage of eversion carotid endarterectomy was confirmed.Conclusion. The good results show not only the high qualification of each operating surgeon as well the entire staff, providing competent logistics and selection of patients for both planned and emergency surgical interventions.

Summary Comparison of two methods of measurements of snow cover thickness on the glacier Austre Grønfjordbreen, Svalbard was performed in the spring of 2014. These methods were the radar (500 MHz) observations and standard snow surveys. Measurements were conducted in 77 different points on the surface of the glacier. A good correlation (R2 = 0.98) was revealed. In comparison with the data of snow surveys, the radar measurements show a similar but more detailed pattern of the distribution of the snow cover depth. The discrepancy between the depths of snow cover on maps plotted from data of both methods did not exceed 30 cm in most parts of the glacier. The standard error of interpolation of the radar data onto the entire glacier surface amounts, on average, to 18 cm. This corresponds to the error of radar measurements of 18.8% when an average snow depth is about 160 cm and 9.4% at its maximum thickness of 320 cm. The distance between the measurement points at which the spatial covariance of the snow depth disappears falls between 236 and 283 m along the glacier, and between 117 and 165 m across its position. We compared the results of radar measurements of the pulse-delay time of reflections from the base of the snow cover with the data of manual probe measurements at 10 points and direct measurements of snow depth and average density in 12 snow pits. The average speed of radio waves propagation in the snow was determined as Vcr = 23.4±0.2 cm ns−1. This magnitude and the Looyenga and Kovacs formulas allowed estimating the average density of snow cover ρL = 353.1±13.1 kg m−3 and ρK = 337.4±12.9 kg m−3. The difference from average density measured in 12 pits ρav.meas = 387.4±12.9 kg m−3 amounts to −10.8% and −14.8%. In 2014, according to snow and radar measurements, altitudinal gradient of snow accumulation on the glacier Austre Grønfjordbreen was equal to 0.21 m/100 m, which is smaller than the average values (0.35 m/100 m). According to the results of snow measurements of 2011–2014, the average thickness of the snow cover on the glacier Austre Grønfjordbreen was by 17 cm greater than in 1979. In the very snowy year 2012, it was higher by 21.5 cm in comparison with the year 1979, and its spatial variability (standard deviation σН) had increased by 25.6 cm. Estimates of spatial and temporal variability of snow cover depth will be used to analyze the hydrothermal state of the glacier and its changes with regard to revealed features and climatic trends.

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Factors of investment attractiveness of the city of Novosibirsk under the conditions of sanctions have been studied, modern anti-crisis mechanisms of its maintenance and stable development have been provided. In the crisis conditions, the main problems, having a negative impact on the image of the city, are demographic problems, poverty and threat of deepening social inequality due to ineffective management of labor market. Anti-crisis measures are offered, which should be realized with due consideration of the main priorities of social and economic growth of the city.

The paper reports results of a comparison of the measured electron density in the ionospheric D-region measured using the partial reflection facility at the observatory. Tumanny of the Polar Geophysical Institute (69.0°N, 35.7°E) with numerical simulations performed using the theoretical model of the Polar Geophysical Institute (PGI) (Murmansk, Russian Federation). The model was examined using experimental data obtained under quiet geomagnetic conditions in March, 2017. The comparative analysis carried out in this study shows a very good agreement of the PGI model with experimental data and indicates that the IRI-2016 model fails to adequately reproduce measurements in regions with high electron density gradients.