Перегляд за Автор "Asadov, H. H."

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    Investigation of Possibility of Measuring the Albedo of Earth’s Surface in Visible and Near Infrared Bands in Conditions of Aerosol Pollution of Atmosphere Using Unmanned Aerial Vehicles
    (КПІ ім. Ігоря Сікорського, 2024) Asadov, H. H.; Alieva, A. J.; Ashrafov, M. G.
    It is well-known that such processes as agricultural activities, urbanization processes, climatic changes leading to abnormal precipitation, etc. affect the magnitude of the Earth’s albedo. At the same time, the results of remote albedo measurement in visible and near infrared bands also depend on the degree of aerosol pollution of the atmosphere. These factors leading to changes in the earth’s albedo lead to the need for periodic measurements of regional values of the albedo of the earth’s surface. There are a number of problems related to measuring the albedo of the earth, related to the spatial and temporal variability of this indicator. These include the dependence of albedo on the zenith angle of the Sun, the need to create albedo measurement networks in the form of numerous geographically distributed pyranometers, the dependence of satellite albedo measurements on the state of the atmosphere, leading to the need for inter-satellite calibration, or groundbased validation measurements. At the same time, the issue of fully accounting for the effect of atmospheric aerosol on the results of measuring the albedo of the Earth’s surface is still open. The article is devoted to the measurement of the Earth’s albedo visible and near infrared bands using UAVs in conditions of aerosol pollution of the atmosphere. The model of single scattering of the optical source signal of an atmospheric aerosol was adopted as the basis of the conducted research. The interrelation of such optical indicators as the optical thickness of the aerosol and the albedo of the Earth’s surface is analyzed. A criterion for the effectiveness of atmospheric measurements using UAVs is proposed, in which efficiency is defined as the ratio of the total radiation entering the on-board spectroradiometer to the amount of extra-atmospheric radiation from the Sun. By switching from a discrete model to a continuous model created to calculate the proposed efficiency criterion, it is shown that with a synchronous change in the optical thickness of the aerosol and albedo, according to the calculated law, the minimum efficiency of measurements of the albedo of the earth’s surface is achieved.
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    Issues of Optimizing Detection of Stealth Aircraft Using Group of Satellites Flying at Different Altitudes
    (КПІ ім. Ігоря Сікорського, 2023) Agayev, F. G.; Asadov, H. H.; Aliyeva, G. V.
    The article is devoted to the optimization of the detection of stealth aircraft using a group of satellites flying at different altitudes and equipped with an infrared reproducing system. The main sources for the formation of the infrared signature of stealth aircraft are the heating of the aircraft casing during flight and the high-temperature plume emanating from the nozzle of the aircraft engine. The necessity of calculating the infrared signature of stealth aircraft is noted. The infrared signature of such aircraft is usually calculated in wide ranges of IR waves. At the same time, there are works according to which it is advisable to use narrow spectral wavelengths for these purposes. A push-pull method of detecting stealth aircraft using satellites flying in a group at different orbital altitudes has been developed. The proposed method makes it possible to increase the signal-to-noise ratio in the resulting informative signal, which is the difference between the signal from the aircraft itself and the background signal within the frame. It is shown that the introduction of a binary control signal depending on the spatial resolution of the distance to the satellites allows minimizing the total background signal coming from a group of satellites. At the same time, an increasing version of this function applied to the sum of signals from the background under a given restrictive condition ultimately increases the signal-to-noise ratio in the system, and also increases the probability of detecting a stealth aircraft using spectrometric devices installed on satellites.
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    Ordered Test Site Method for Onboard Measurement Results Validation of Medium Resolution Spectroradiometers
    (КПІ ім. Ігоря Сікорського, 2022) Asadov, H. H.; Alieva, A. J.
    The reduction or elimination of uncertainties is one of the main tasks in the analysis of remote sensing data. For this purpose, the upscaling and downscaling of spectroradiometric data operations are widely used. The downscaling operation is particularly used to validate medium resolution spectroradiometer data. The onboard measurement validation data is a complex task and it includes the solution of such important subtasks as (a) selection of the test site type; (b) determining the site size; (c) determining the sampling order. At the same time, after carrying out selective measurements, the question of scaling up (upscaling or generalization) of the obtained ground data arises, its purpose is to carry out validation of satellite data with low spatial resolution. Solving the problem of remote sensing data validation, terrestrial test sites are often used, their heterogeneity must always be taken into account. This problem is usually solved by applying special weighting coefficients and performing temporary periodic measurements, then using the regularization procedure for the averaged results of iterative calculations. In the absence of temporary changes, the need for regularization is eliminated. In this case, as an alternative, the method of the ordered test section can be proposed, it allows to determine the weight coefficients of the ground validation measurement results, providing a minimum of the newly proposed quadrature cost function. To solve the problem of achieving the proposed cost function minimum, the ordered subsections method as part of a single heterogeneous test section is proposed, the measurements are carried out by a sensor mounted on a low-flying carrier. The optimization problem is formulated to calculate the correction coefficients for the measurement results, where the sum of the squares of difference between the corrected data and the known representative estimate is minimized. The optimization problem is solved using a certain restrictive condition imposed on the sum of the correction factors.