Vol 25, No 4 (2024)

Underwater archaeology and, in particular the study of shipwrecked vessels, is one of the more advanced fields in the discipline as it employs a spectrum of technical and scientific methods. Shipwreck detection and identification has been a test ground for a range of theoretical and applied approaches, such as probability theory and mathematical statistics, namely the Bayesian Search Method, which has been successfully applied for this purpose in a number of renowned international projects. In this paper we shall cover the fundamental principles of using this method to assist search efforts in determining the location of historic underwater shipwrecks. As such, the novelty of this paper consists largely in acquainting the Russophone researcher with the Bayesian Search Method in submarine exploration as very little has been published on this subject in Russian literature. As will be shown here, there does exist a demand for the application and perfection of probability search methods for underwater archaeology in the country. In 2024, an expedition to the Yenisei Gulf discovered the shipwrecked steamer Tbilisi, which sank in 1943 after striking a mine installed by the Kriegsmarine. Despite having exact charts and knowing the exact coordinates of the shipwreck, the search team had to spend hours in high seas before finally managing to detect the vessel using side-scan sonar. Applying the Bayesian Search Method would have significantly reduced the time and labor intensity of the search. Besides the search method proper, we shall consider the arrangement of a specialized database for the architecture of a suggested software application, the purpose of which is building probability distribution maps to assist the search and identification of shipwrecked vessels.

Due to the difficulties that arise when using satellite navigation systems at airfields at present, and the insufficient accuracy of inertial navigation systems, optical measuring systems have again begun to be used to carry out trajectory measurements. However, existing measuring systems have a number of disadvantages. The purpose of this work is to describe a method for increasing the accuracy of trajectory measurements obtained by the goniometric method. The article reviews the main algorithms currently used in trajectory measurements and their shortcomings. An algorithm for frame-by-frame post-flight processing of recorded video from cameras of an optical-electronic measuring complex is proposed. A description of the implementation of this algorithm is given, taking into account the specifics of graphical software interfaces for processing user of the algorithm’s input. The proposed algorithm allows, after carrying out trajectory measurements, without time restrictions, to correct pan and tilt of the platform at each moment in time. The proposed algorithm makes it possible to increase the accuracy of trajectory measurements when testing aircraft, both already carried out and future ones. The proposed algorithm can also be used to obtain would-be pan and tilt of the camera when implementing a goniometric direction-finding complex using fixed wide-angle optical cameras. For example, when measuring the radiation patterns of an aircraft's onboard antennas using a quadcopter-meter to determine its position in space at each moment in time. The article also presents the main advantages and disadvantages of the algorithm, makes proposals for its improvement, and suggests possible areas of its application.

The article considers the design and development of a computer model of the fueling monitoring and control panel of the Sukhoi SuperJet 100 civil aircraft. The presented model is included in a simulator program for training technical specialists in aircraft maintenance skills under conditions of limited access to real or hardware-simulated equipment.

In the process of designing of the presented simulation model, the refueling panel and the SSJ-100 aircraft refueling system sufficient components were considered and selected for further software implementation. The selection of the necessary components for the model was carried out using the decomposition method of the real system. First, the functional elements of the refueling panel itself were selected, after which the refueling system was disassembled into components that allow simulating the operation of the simulated panel.

To implement the simulation model, software classes of objects and interactions between them were described. Software algorithms are implemented in the Unity environment using the C# language. The created program uses a three-dimensional graphic component and compiled for launching on a web browser. Software components have also been developed that allow studying the functions of the fueling panel both independently and in the mode of control of knowledge of the elements and algorithms for working with the fueling panel.

The developed model is used as part of a practical simulator at the Reshetnev Siberian State University, and can be functionally expanded in the future.

The accuracy of determining coordinates in global positioning systems is determined by the number of satellites simultaneously visible to the consumer's navigation equipment. Over most of the earth's surface, there are up to 11 GLONASS satellites above the horizon at the same time, but the signal-to-noise ratio in the communication channel required for error-free information reception is often ensured only for 2-4 satellites. To improve the positioning accuracy, it is proposed to use the holographic noise-immune coding method based on the holographic representation of the digital signal. The message coding process is a mathematical modeling of a hologram created in virtual space by a wave from the input signal source. It is shown that the holographic representation of the signal has significantly greater noise immunity and allows restoring the original digital combination when most of the code message is lost and when the coded signal is distorted by noise several times exceeding the signal level. The studies have shown that the introduction of holographic coding in the GLONASS satellite communication channel will enable consumer navigation equipment to receive information from a larger number of satellites, which will significantly improve the positioning accuracy. In a common situation where the required signal-to-noise ratio is maintained for only 4 GLONASS satellites, the positioning error exceeds 10 meters. Using holographic coding in the same situation, information from 9 satellites will be decoded without error, and the positioning error will be about 2 meters.

A special interest in the topic of mathematical analysis of the flow of heat transfer processes is determined by the scientific significance and practical application in the development, design and production of rocket and space vehicles and installations. Substantiation of the developed techniques and modeling of the data obtained during the experiment using 3D process technologies gives an advantage. The accuracy and reliability of the calculation results play a key role in ensuring the safety and reliability of rocket and space systems. Regular verification and verification of the results are also necessary to ensure a high degree of reliability and safety. The comprehensive analysis of the fluid flow in the inter-vane channel of the impeller of a low-flow centrifugal pump presented in the article, with the construction of the energy characteristics of the impeller, can be used to clarify the number of vanes. The developed calculation method consists of four parts: firstly, an expression is obtained to determine the projection of the pressure gradient on the longitudinal axis φ, secondly, an expression is obtained to determine the projection of the pressure gradient on the transverse axis ψ, thirdly, the derivative of the longitudinal velocity in the transverse direction is determined, and fourthly, the results are presented numerical and experimental visualization: the power balance, the dependence of the pressure and the coefficient of influence of a finite number of vanes on the flow rate of a low-flow centrifugal pump. Based on the results of theoretical research, an algorithm and a calculation program were developed that allows calculating local values. The considered approach is confirmed by verification of the results of mathematical modeling by graphical visualization of the flow and measurement of the power balance of a low-flow centrifugal pump. The obtained expressions for pressure gradient projections, determination of the derivative of the longitudinal velocity and experimental visualization play an important role in the calculation and analysis of the operation of centrifugal pumps. However, there is a need for further elaboration of the method to bring it to a form that allows calculating the three-dimensional flow of the working fluid in an arbitrary channel.

Instruments measuring the Earth's magnetic field are widely used in the space industry. Increasingly, low-orbit spacecraft orientation and stabilization systems include magnetometers manufactured using magnetoresistive technology. This is justified by the low weight, size and consumption of such devices, which makes them ideal for use on small-sized spacecraft. However, the main problem of magnetoresistive magnetometers is the need to estimate possible measurement errors. The influence of errors significantly reduces the accuracy characteristics of the device. In order to solve the problem, researchers propose various methods for evaluating and eliminating the influence of errors on measurements [1–7]. Among the ways to eliminate errors in the readings of the device, constructive solutions are used, such as putting the device at a distance from the spacecraft using a retractable boom, in order to reduce the influence of interference on the device from the device [2]. Such a solution is advisable for large spacecraft, where the presence of a retractable boom will not complicate the design and will not increase energy consumption. For small spacecraft, such a solution is not advisable, for this reason, when discussing small-sized spacecraft magnetometers, much attention is paid to calibration methods, mathematical evaluation and error correction, both in ground and in flight conditions. The objectives of the article include the formation of a general understanding of the causes of distortions in the readings of anisotropic magnetoresistive magnetometers, methods of their mathematical evaluation. A review of methods and equipment for ground calibration is carried out. The characteristics of the calibrated parameters of magnetometers are given and a mathematical model of measurement of the device is proposed, taking into account errors. The basic operations and equipment used in the calibration process are described. The results of the work can be useful in designing workplaces for calibrating magnetometers, as well as in conducting empirical research in the field of magnetometric sensors.

Carbon nanostructures have been in the focus of world science for more than 25 years, since the discovery of fullerenes in 1985, single-walled carbon nanotubes in 1993, graphene in 2004, graphene quantum dots in 2004. Graphene is a monocrystalline graphite films (2D material) with a thickness of several atoms that are stable under environmental conditions and they have excellent electronic, mechanical, chemical, thermal and optical properties. All over the world, research and development of new methods of using graphene in various fields such as energy, oil production, materials science, and electronics are actively carried out. Currently, the use of graphene-containing materials as modifiers for the creation of durable and effortless materials in aviation, automotive and other branches of engineering is an urgent problem. It is advisable to introduce graphene particles into the composition of composite materials using their stable dispersions in a liquid medium. The production of colloidal graphene suspensions is effective in many cases using the method of liquid phase exfoliation of graphite.

The paper presents the results of studying the physico-chemical properties of aqueous graphene suspensions obtained by liquid-phase exfoliation of natural graphites using high-speed hydrodynamic technology. Graphite grades GK-1 and GAK-2 (Grafitservice, Chelyabinsk, Russia) are crystalline graphites obtained by enrichment of graphite ores and joint enrichment of natural graphite ores and graphite-containing waste from metallurgical industries, respectively. Graphite suspensions were prepared in distilled water with 1 wt.% graphite, surfactant was added to some samples, processing time (3–120 min), rotor rotation speed (4 000–11 000 rpm). The resulting graphene suspensions were investigated by XRD, by electron microscopy and sedimentation analysis methods. The particle size was determined using the DT-1202 electroacoustic spectrometer. The presence of multilayer graphene is confirmed by comparing the results of XRD with the literature data. Along with multilayer graphene, the presence of graphene dots was detected. Aqueous graphene suspensions for graphites with different sedimentation times have been obtained. For graphite GAK-2 – six days, for graphite GK-1 – 90 days, for graphite GK-1 + surfactant – 6 months.