Vol 22, No 1 (2021)

Recently the reversible cellular automata are increasingly used to build high-performance cryptographic algorithms. The paper establishes a connection between the reversibility of homogeneous one-dimensional binary cellular automata of a finite size and the properties of a structure called «binary filter with input memory» and such finite automata properties as the prohibitions in automata output and loss of information. We show that finding the preimage for an arbitrary configuration of a one-dimensional cellular automaton of length L with a local transition function f is associated with reversibility of a binary filter with input memory. As a fact, the nonlinear filter with an input memory corresponding to our cellular automaton does not depend on the number of memory cells of the cellular automaton. The results obtained make it possible to reduce the complexity of solving massive enumeration problems related to the issues of reversibility of cellular automata. All the results obtained can be transferred to cellular automata with non-binary cell filling and to cellular automata of dimension greater than 1.

One of the key problems in the development of nanosatellites is to provide a given temperature range for the operation of the on-board computer. The constantly increasing information load leads to the need to use more advanced processors with high thermal design power (TDP). The indicated thermal regime of processors can be achieved using remote heat removal systems - miniature loop heat pipes. Using a model of nanosatellite as an example, a thermal control system with miniature loop heat pipes is designed. The simulation was carried out in the Siemens NX program in the elliptical and geostationary orbits of the Earth. The cooling schemes of the processor with a thermal power of 15 W using one and two loop heat pipes are considered. Calculations showed that the use of loop heat pipes can reduce the processor temperature to acceptable values. The anisotropy of the thermal conductivity coefficient in the reinforcement plane of the composite material of the nanosatellite case can have a significant effect on the temperature of the processor. This opens up prospects for the use of anisotropic composite materials to ensure the thermal regime of the nanosatellite.

The relevance of the issue under consideration is associated with the evolution of existing technologies, due to which the functionality increases and the mass of the payload decreases, as a result of which the question of the use of cost-effective launch vehicles is raised. The purpose of this work is to carry out a comparative analysis of the feasibility of using ultra-light launch vehicles to provide services for the delivery of small spacecraft to low-earth orbit. The article is written within the framework of socio-economic research methods. Retrospective analysis and comparative approach are combined with the use of quantitative methods. The theoretical significance of the study consists in the analysis of the modern operation of small spacecraft and the state of the world rocket and space industry, analysis of the existing strategy of the State Corporation «Roscosmos» in the development of a new line of reusable launch vehicles and consideration of promising projects of domestic private companies involved in the creation of ultra-light launch vehicles. The practical significance lies in the possibility of using the results of studying the intensity of space launches when making strategic decisions on the use of ultra-light launch vehicles. Based on the assessment of existing forecasts for the development and creation of small-sized spacecraft, it is concluded that the world space market is interested in the types of satellites and classes of launch vehicles for their launch.

The blades of contemporary turboprop engines have a complex spatial configuration. They can be classified as shells. Methods for the shells calculation are well known. A number of computer programs have been created on their basis. However, these programs do not take into account the peculiarities associated with the mutual influence of deformations of the blade and the aerodynamic and inertial loads acting on it. The aim of this work is to develop a method of finite element calculation of aircraft propeller blades taking into account aeroelastic effects and to create a computer program on its basis that is available to a wide range of designers and engineers. The finite element method is used in a geometrically nonlinear formulation. As the initial one, the equilibrium equation is used, which includes a complete nonlinear stiffness matrix and takes into account both conservative and non-conservative loads. The blade of one of the serial propellers was calculated. The effect of deformations on the magnitude of the aerodynamic load and, as a result, on the stresses in the design sections was found and analyzed. The proposed technique and the program compiled on its basis can be used in the design of aircraft propeller blades.

The architects working with the shell use well-established geometry forms, which make up about 5-10 % of the number of known surfaces, in their projects. However, there is such a well-known surface of rotation, which from the 19th century to the present is very popular among mathematicians-geometers, but it is practically unknown to architects and designers, there are no examples of its use in the construction industry. This is a pseudosphere surface. For a pseudospherical surface with a pseudosphere rib radius, the Gaussian curvature at all points equals the constant negative number. The pseudosphere, or the surface of the Beltram, is generated by the rotation of the tracersis, evolvent of the chain line. The article provides an overview of known methods of calculation of pseudospherical shells and explores the strain-stress state of thin shells of revolution with close geometry parameters to identify optimal forms. As noted earlier, no examples of the use of the surface of the pseudosphere in the construction industry have been found in the scientific and technical literature. Only Kenneth Becher presented examples of pseudospheres implemented in nature: a gypsum model of the pseudosphere made by V. Martin Schilling at the end of the 19th century.

Pipelines are widely used in recent decades because their eco-friendliness, safety and profitability of transportation. Their length can be more than hundreds and thousands of kilometers. Submarine pipelines got wide distribution. Their constructing must comply with regulatory documents. But even it can’t guarantee no problems during operation. This study contains review of the different research, connected with floating of a submarine pipeline problem. Information about conducted research and their conclusions is summarized in this paper. Direction for the future investigations is shown. Submarine pipelines are subjected to vertical movement (floating). Pipeline ballasting method is used to avoid this situation. Ballasting by loading bags is considered in this article. This study contains review of the different research, connected with floating of a submarine pipeline problem. Calculations required for the correct selection of the loading bags weight are performed, possible reasons for floating are described. This article will be useful for submarine pipeline designers.