卷 22, 编号 2 (2021)

The article presents the problem of optimizing the structure of information processing computer appliances for real-time control systems used, among other things, in the rocket and space industry. In addition, the features of this problem that affect the choice of optimization methods are studied. It’s concluded that this problem can be effectively solved using evolutionary optimization methods.

Existing performance models allow you to determine the minimum hardware configuration of a multiprocessor computing system. The approach proposed in this article allows us to find configurations that have hardware redundancy (compared to the minimum configuration), but, due to this, have a greater probability of being in states that provide performance sufficient to achieve the goals of functioning of the designed real-time control system. The described approach is more flexible than simply duplicating all hardware components of the minimum configuration, which can be used to reduce the cost of creating and operating the designed control system.

The proposed model can be used to optimize the performance of multiprocessor hardware and software complexes of real-time control systems. At the same time, it should be taken into account that the resources allocated for the creation and operation of the hardware and software complex are always limited. Therefore, it is advisable to consider the problem of performance optimization as a multi-criterion: one criterion will be performance, and the other-the cost of creating a hardware and software complex.

In calculations for the strength of elastic composite structures (plates, beams, shells), which are widely used in aviation and rocket and space technology, using the finite element method (FEM), it is important to know the error of the solution. To analyze the error of the solution, it is necessary to use a sequence of approximate solutions constructed according to the FEM using the grinding procedure for discrete basic models (BM), which take into account the inhomogeneous, micro-inhomogeneous structure of structures (bodies) within the micro-approach. Discrete models obtained by grinding BM have a high dimension, which makes it difficult for them to use FEM. In addition, there are BM of composite bodies (CB), for example, BM of bodies with a micro-inhomogeneous structure, which have such a high dimensionality that the implementation of FEM for such BM, due to the limited computer resources, is almost impossible. To solve these problems, it is proposed to use fictitious discrete models in the calculations of the CB according to the FEM.

In this paper, we propose a method of fictitious discrete models (MFDM) for calculating the strength of elastic bodies with an inhomogeneous, micro-inhomogeneous regular structure. MFDM is implemented using FEM with the use of adjusted strength conditions that take into account the error of approximate solutions. The method is based on the following statement. We believe that BM CB generates solutions that differ little from the exact ones. Due to the convergence of the FEM, such BM for CB always exist. The calculation of CB according to MFDM is reduced to the construction and calculation of the strength of fictitious discrete models (FM), the dimension of which is less than the dimension of the BM. FM reflects: the shape, characteristic dimensions, attachment, loading, and appearance of the heterogeneous structure of the CB, and the distribution of elastic modulus corresponding to the BM of the CB. The sequence consisting of the FM converges to the BM, i.e. the limiting FM coincides with the BM. The convergence of such a sequence ensures uniform convergence of the FM stresses to the corresponding BM stresses. The implementation of FEM for FM with the use of multigrid finite elements leads to a large saving of computer resources, which allows the use of MFDM for strength calculations of bodies with a micro-inhomogeneous regular structure. The calculation of the strength of CB according to MFDM requires 10³÷10⁶ less computer memory than a similar calculation using BM CB, and does not contain a procedure for grinding BM. The given example of calculating the strength of a beam with an inhomogeneous regular fiber structure according to the MFDM shows its high efficiency. The use of adjusted strength conditions allows us to use approximate solutions with a large error in the calculations of CB for strength, which leads to an increase in the efficiency of MFDM.

Modern and promising dynamic systems of aviation weapon systems of the Aerospace Forces (hereinafter for brevity in the text – the system) are characterized by a more complex structure and increased requirements for reliability and efficiency of functioning. Moreover, systems of generation 4 ++ and 5 are quite unique and (or) small-scale, and their constituent elements are basically miniature and expensive, therefore, a prerequisite for fulfilling the requirements for traceability to systems and constituent elements is the maximum possible preservation of the quality of the initial basis with the inevitable new interpretation of additional information. Further introduction of artificial intelligence technologies into the practice of solving problems of technical diagnostics makes it possible to obtain adequate results with almost any accuracy. The reliability of the results will be determined solely by the punctuality of the data assignment and the completeness of the mathematical description of systems, processes and events in the subject area under consideration. Therefore, it should be expected that the further development of the theory and practice of technical diagnostics will follow the path of a deeper study of the physical processes occurring in systems, and a more accurate mathematical specification of procedures for finding the place of failure of systems. The aim of the work is to establish the development of an interconnected set of mathematical and logical block diagrams for obtaining and applying diagnostic knowledge in the software and mathematical support of modern and advanced onboard means of monitoring the technical state of systems. The priority direction in such studies is the differentiated selection of approved methods of technical diagnostics with the choice of the appropriate mathematical and algorithmic apparatus for direct probabilistic modeling of systems. A block diagram is presented and a variant of the practical application of the developed algorithm for sequential recognition of system failures (hereinafter referred to as an algorithm, if it is clear from the context of the presentation of the material that it is the developed algorithm) is considered. By using the algorithm, there is no need for decomposition of systems, and the potential for multiple repetitions of the results of a random process of changing the technical states of systems predetermines the possibility of obtaining large samples with high accuracy of software compilation.

Many developers of new high-thrust solid-propellant rocket engines are faced with the problem of acoustic instability of combustion. The phenomenon of resonant combustion of solid fuel is associated with a number of specific features. The cavities of the combustion chambers of such engines have complex geometric shapes. The gas channel is long enough. Its length usually exceeds five or more calibers. The thickness of the flame front is measured in micrometers and the combustion zone is localized over the open fuel surface. The flame front often turns out to be capable of amplifying pressure perturbations at the frequency of one of the acoustic eigenmodes if the wave antinode falls on a thin combustion zone. The oscillatory process can be regular or sporadic. Resonances of the longitudinal acoustic mode are most often observed. However, there were cases of simultaneous oscillation of two modes. In some cases, during the operation of the engine, the amplitude of the resulting oscillations began to decrease and the combustion process became almost quasi-stationary. Self-oscillatory processes in the combustion chambers of solid propellants have a threshold sensitivity to pressure overshoots. The vibration amplitudes can be several tens of percent, sometimes reaching the nominal working pressure in the chamber. The amplitude-frequency characteristics of the oscillations are sensitive to the composition of the fuel, responding to changes in the chemical composition, as well as to the mechanical properties of the fuel. The regions of unstable regimes are definitely related to the geometry of the gas cavity. Together with pressure fluctuations, the combustion process is influenced by gas-dynamic factors, significant non-uniformity of the gas flow parameters along the length of the channel, its turbulence, and other factors. When designing solid rocket motors, it is necessary to estimate the frequencies of the natural acoustic resonances of the combustion chambers.

The article discusses a technique for determining the frequencies of natural resonances of the first and second tone of the longitudinal mode of acoustic vibrations in the combustion chambers of solid propellant rocket engines. The gas path of the combustion chamber is divided into homogeneous sections, for which the solutions of the wave equation are presented. To determine the natural frequencies and distribution of vibrational pressures and velocities, the method of "stitching" acoustic fields at the boundaries of the cavities was used.

The paper presents the optimization of the location of the interface points of the spacecraft instrument panel using modal analysis, as well as a quasi-static calculation of the panel under study, confirming the effectiveness of the proposed changes in the panel design. The instrument panel is a three-layer honeycomb structure consisting of two aluminum plates and a honeycomb filler. Cellular panels have a number of advantages: a small weight of the structure, high rigidity, specific strength. Using finite element modeling, the range of natural frequencies and vibration patterns of the instrument panel was determined, which made it

possible to determine the optimal location of the panel attachment points to the spacecraft body to increase the lower limit of the natural frequency range and increase its carrying capacity.

In this paper, we consider the concept of using methods for calculating and designing rocket engine power plants for conversion modeling of local energy in the Arctic and northern regions of the Krasnoyarsk Territory, with an obvious generalization to neighboring administrative formations with similar climatic and structural and logistical conditions. The proposed structure contains power generation units linked to both industrial woodworking waste and natural and industrial heat tailings, identified as sources of low-potential heat, as well as modern low-power reactor plants of block maintenance-free design. The unifying element of power plants is a turbo generator, designed with the use of unconventional, often waste and natural low-potential heat.

MAX-phases are a family of ternary layered compounds with the formal stoichiometry M_n+1AX_n (n = 1, 2, 3...), where M is a transition d-metal; A is a p-element (for example, Si, Ge, Al, S, Sn, etc.); X is carbon or nitrogen [1]. Layered triple carbides and nitrides of d-and p-elements (MAX-phases) exhibit a unique combination of properties characteristic of both metals and ceramics, which makes their application as various coatings in space industry very promising. Obtaining the desired properties of the MAXphases depends on the technological conditions of material synthesis. This requires thorough theoretical modelling of the elements’ interaction at the interface. Concurrent growth of competing phases along with the MAX-phase may occur due to the favorability of the formation of competing phases and also be promoted by lower energy interfaces with the substrate in comparison with a MAX-phase. In this work, we study thermodynamic favorability of competing phases and Cr₂GaC MAX-phase depending on the chemical composition of the atomic flow. To study these compounds, it was necessary to consider the Cr-Ga-C system. According to the effective heat of formation model, each reaction of the formation of a certain phase can be characterized by enthalpy [2]. To find out the most favorable phases, it was necessary to calculate the enthalpy of all possible reactions. Thus, the task was to sort through all possible reactions between pure elements available in various ratios, in particular, in the ratio corresponding to the given MAX-phase stoichiometry, i.e. Cr:Ga:C=2:1: 1. Moreover, it is considered that the density of near-coincidence sites [3,4] for interfaces between MAX-phase, thermodynamically favourable competing phases and MgO(111) surface shows a role of the interface in the determination of the structural quality of the MAX-phase thin film grown on MgO(111).

High-tech devices improvement requires development of technology and search for new materials from science. To date, the development of the magnetism research field has reached a very broad knowledge, which made it possible to create and study a variety of artificial ferromagnetic materials, which are already actively used in science and technology. The latest scientific knowledge shows that the same material in different states can exhibit different electrical and magnetic properties. So, thin magnetic films are actively used in modern devices. Physical processes in thin films proceed differently than in bulk materials. As a result, the film elements have characteristics that differ from those of bulk samples and make it possible to observe effects that are not characteristic of bulk samples. A film is a thin layer of a bound condensed substance, the thickness of which is compared with the distance of surface forces action; it is a thermodynamically stable or metastable part of a heterogeneous film-substrate system. Further study of film structures led to the creation and study of multilayer magnetic systems. In such structures, the presence of both various ferromagnetic materials layers and non-ferromagnetic interlayers is possible, and the multilayer systems properties can differ significantly from the properties of any system components. These materials also have many applications for practice, including radio communications and geological exploration. In our experiment, ferromagnetic thin films of Fe₃Si silicide were synthesized by molecular beam epitaxy with co-deposition of Fe and Si. A polycrystalline silicide film was obtained on a SiO₂/Si(111) substrate, and a single crystal film was on Si(111)7×7. The structure was investigated using the diffraction of reflected fast electrons directly during the growth process. The magnetic anisotropy of the obtained samples was studied by the ferromagnetic resonance. It was found that the polycrystalline film is characterized by uniaxial magnetic anisotropy, which is 13.42 Oe and is formed as a result of “oblique” deposition. And the magnetic anisotropy for a single-crystal Fe₃Si film is formed to a greater extent by internal magnetocrystalline forces.