Siberian Aerospace Journal

Autonomous Navigation is very important in many fields and applications and it specifically depends on Global positioning System (GPS ) measurements which in some areas it suffers from absence, this will directly affect the Autonomous Navigation and sequentially this will lead to problems according to the function of Autonomous Navigation. In this research, generalized regression neural network (GRNN) which is a variation to radial basis neural networks, was used to compensate Global positioning System (GPS) measurements in case of GPS absences to increase accuracy of Autonomous Navigation parameters (basically Location and Velocity) of object. GRNN is integrated with loosely coupled Extended Kalman Filter (EKF). Location, velocity, orientation parameters and Biases of sensors are estimated. The evaluation of this methods was conducted using dataset from Internet, two outages of GPS measurements are made (first outage periods are 35 and 60 seconds) to evaluate the behavior of GRNN, the results showed that using GRNN in GPS absence is effective and robust, it outperformed the only loosely coupled EKF method.

In this paper, an analytical method is proposed for solving the problem of magnetometer calibration for the model considered in [1]. When solving the problem of determining the calibration parameters of the magnetometer unit, it is taken into account that for measurements with any spatial orientation of the magnetometer unit, the value of the measured magnetic induction vector is preserved and is a known model value. A penalty function of 12 variables equal to the sum of the squares of the residuals is introduced into consideration. The algorithm for solving the problem of calibrating the measuring axes of the magnetometer unit is reduced to searching, by the method of least squares, for such values of the variables of this function that, for a given set of magnetometer measurement vectors, provide it with a minimum. For this purpose, the specified function is examined for a conditional extremum in the presence of three equality constraints. The Lagrangian function is compiled and, based on the necessary condition for the extremum of this function, the system of 15 equations in the 15 variables is formed. It is proved that the system has four solutions. Formulas are derived that make it possible to obtain the components of each of these four solutions. As a solution to the magnetometer calibration problem, it is recommended to choose a solution to the specified system that provides a minimum of the Lagrangian function.

The development of unmanned aircraft systems is becoming one of the key areas of Russia's scientific and technological development. Within the framework of the approved strategy until 2030, it is planned to form a new industry specializing in the creation and use of civilian drones, and priority areas for the development of unmanned technologies have been identified. The great potential for the use of unmanned vehicles is observed in the creation of geospatial databases. In this connection, when using autonomous aerial platforms for aerogeophysical works, the issues of improvement and development of information-measuring systems used on such carriers, as well as the issues of training of operators of aerogeophysical systems become relevant. The development of algorithmic and software of information-measuring systems on the basis of implementation of previously created electronic content: reference materials, instructions for work, operation of instrumentation products, protocols for processing of obtained results, decision-making techniques, etc. is becoming important. However, the application of such electronic content carries risks of reducing the quality of surveying works. One of the ways of risk assessment is to combine the traditional qualitative and categorical approach of modern risk management with multilevel representation of the hierarchy of aggregation of expert-assessed risks in the composition of summary and integral risks by applying the apparatus of soft computing. For systematization and prioritization of risks it is proposed to use gradation scales and terms of linguistic variables of risk components associated with the probability of occurrence of a decrease in the quality of content of information support of operator training systems, with the potential value of possible damage in the event of the fact of a decrease in the quality of information support. As a result, it becomes possible to develop a risk-assessment model, which is a procedure for the specific construction of matrices of consequences and probabilities for individual risk-indicators of the assessment of the integration of electronic content in the information support of training systems for operators of information-measuring systems of aerogeophysical applications. This procedure is a logical basis for calculation of summary and integral values of risk-indicators of assessment, as well as gradation of risk levels.

This article addresses the Express-RV satellite system, which developers are currently creating. Its primary purpose is to provide subscribers in the Russian Federation and the Northern Sea Route with internet access. The subject of the study is the main features of the Express-RV system implementation, concerning communication in the forward and reverse satellite channel. Among the main features of the satellite system, in addition to the highly elliptical orbit (HEO), we can highlight multi-beam coverage of the service area, direct signal retransmission and the choice of DVB-S2X and DVB-RCS2 satellite communication standards. To implement multi-beam coverage of the service area and direct retransmission, the system employs a multi-beam Ku-band payload. Therefore, the work prioritizes the description of this payload.

Objective of the work: to analyze the features and energy parameters of the Express-RV satellite system to confirm its operability, as well as to determine the operating modes in the forward and reverse channels according to the DVB-S2X and DVB-RCS2 standards.

Methodology: analysis of the main solutions of the Express-RV system being developed, the DVB-S2X and DVB-RCS2 satellite standards and the recommendations of the International Radiocommunication Union ITU-R P.618-13, theoretical calculation of the energy budget of the radio link.

The results confirm the system’s operability, as the study demonstrates the possibility of quasi-error-free reception of DVB-S2X and DVB-RCS2 signals under ideal synchronization conditions. In addition, based on the calculation, we identify the actually used types of modulation in the return channel from those presented in the DVB-RCS2 standard for 3 types of subscriber terminals. For the forward channel, the analysis reveals that the transmission mode adapts to the terminal with the smallest reflector diameter, eliminating benefits from larger-aperture terminals.

Scope of application of the results: the researchers and engineers use the results to further develop the Express-RV satellite system.

The relevance of the study is due to the need to improve the reliability and durability of steam turbines, which are widely used in the energy industry. One of the critical factors affecting the performance of turbines is the occurrence and development of cracks in the blades, which can lead to their destruction and emergency situations. This type of defects can significantly change the dynamic characteristics of a structure, reducing its life and increasing the likelihood of failure. Therefore, analyzing the effect of cracks on the vibration parameters and strength of blades is an important task for predicting their reliability and developing diagnostic methods.

This article examines the effect of cracks on the dynamic and strength characteristics of steam turbine blades. The object of the study is a working wheel made of 304 stainless steel. The finite element model in the ANSYS Workbench environment was used for the analysis. The natural frequencies and vibration mode of the blades at different angular speeds of rotation, as well as the effect of cracks of various lengths on the dynamic characteristics of the structure, are investigated. The analysis results show that the presence of a defect leads to a decrease in natural oscillation frequencies, especially for low-frequency forms of bending vibrations. In addition, the effect of crack growth on the durability of the blades and the entire working wheel has been studied. It has been found that increasing the crack length significantly reduces the life of the blades, and the durability of the working wheel decreases more slowly due to the interaction of the blades with each other. The obtained results can be used in the development of methods for diagnosing and predicting the life of turbomachines, as well as to optimize their design in order to increase operational reliability.

This article describes the results of monitoring the radiation situation in a medium circular orbit, obtained from the data of the experimental dose control complex (EDCC) of the spacecraft, developed by JSC “Reshetnev”, with a circular orbit at an altitude of H=8070 km. The article compares the experimentally obtained EDCC data with the calculated data, obtained during flight operation over two years of research. It should be noted that this orbit is poorly studied by Russian spacecraft developers in terms of the impact of space factors. Also considers the effect of the extreme geomagnetic disturbance in May 2024 on the rate of accumulation of the absorbed dose.

The method of conducting the experiment consists of creating different conditions of mass protection for each of the nine sensors. The mass protection is varied by installing a steel grid with different cell thicknesses. Thus, each sensitive element is in unique irradiation conditions – mass protection weakens the flux of ionizing radiation and changes its spectrum (differently for each type of radiation).

When developing a new type of orbit for spacecraft operation, the task of ensuring the resistance of onboard equipment and the spacecraft as a whole to the effects of ionizing radiation factors of outer space, typical for this orbit, is relevant. For this, experimental confirmation or refinement of the calculated radiation model of impact based on the obtained in-kind data is necessary.

The main task solved in the article is to monitor the levels of the integral accumulated dose behind various protections when exposed to ionizing radiation of outer space at an orbit of 8070 km and to compare the results of experimental data with the calculated estimates carried out according to OST134-1044-2007.

The article reflects the results of long-term measurements of the absorbed dose of ionizing radiation for a spacecraft with such an orbit. As a result of the measurements, it was established that after an extreme magnetic storm, there is a significant increase in the rate of dose accumulation. This led to the dose recorded for 722 days exceeding the calculated valueю.