Vol 22, No 1 (2021)

The reversibility of one-dimensional cellular automata

Zhukov A.E.


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.

RUDN Journal of Engineering Research. 2021;22(1):7-15
pages 7-15 views

Applicability analysis of prediction methods in the system for selection personalized offers by analytical modeling

Fedorenko Y.S.


The relevance of the work is justified by the frequent occurrence of the need to solve the problems of choosing personalized offers in information systems and the many possible methods of machine learning, among which it is necessary to choose the most suitable one. The purpose of this study is to simulate a system for selecting personalized offers as a queuing system for estimating equipment costs when using each of the methods necessary to service the required part of requests for a given time limit. This solves the problem of assessing the minimum number of servicing devices (backend servers) required to ensure the operation of the system at a given level. The paper shows that the system can be described by a multichannel queuing system without losses. The distribution function of the spent time of the request in the system (the service time plus the waiting time in the queue) is calculated, since in the literature for such systems only the distribution function of the waiting time in the queue is described. Transformations of the expression for the probability of waiting are given, which solve the overflow problem in the software implementation. In the final part, as an example, the system was modeled according to the given parameters, and the minimum number of servicing devices was estimated to ensure a given system response time. Based on the data obtained, it is possible to make a decision on the advisability of using one or another method for predicting the frequency of user clicks or ranking.

RUDN Journal of Engineering Research. 2021;22(1):16-22
pages 16-22 views

Simulation of the thermal control system of nanosatellite using the loop heat pipes under the orbital flight conditions

Wang Y., Denisov O.V., Denisova L.V.


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.

RUDN Journal of Engineering Research. 2021;22(1):23-35
pages 23-35 views

Stress-strain state analysis of the design of full-turning vertical empennage for aero-spacecraft

Chistyakov A.A., Timoshenko V.P.


In this work, the most rational schemes to designing the skin of a full-turning vertical empennage element (stabilator) have been studied. Skin designing schemes were chosen according to aero-spacecraft operating conditions in the re-entry trajectory. During designing process, the requirements for reusable structures of tourist-class aero-spacecrafts were taken into account, such as: maximum simplicity and endurance of the product. To determine the mechanical loads acting on the keel during its movement in the air, a numerical simulation of the aerodynamic flow-around the stabilator profile at 5 arbitrary points on the flight path was carried out. The parameters used for the analysis are: flight velocity, density and viscosity of the air. Of the 5 obtained fields of dynamic pressure acting on the stabilator, the field that creates the largest distributed load was used as the boundary condition for the analysis of the stress-strain state of the structure. The problem of mechanical loading of the stabilator was solved separately for each of the previously studied structural schemes of the skin. Based on the obtained calculation results the optimal skin structural scheme was chosen by comparing the displacements on the line connecting ribs.

RUDN Journal of Engineering Research. 2021;22(1):36-42
pages 36-42 views

Comparative analysis of the economic feasibility of using ultra-small spacecrafts

Nazarova Y.A., Tikhonov V.A.


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.

RUDN Journal of Engineering Research. 2021;22(1):43-53
pages 43-53 views

Methodology for managing the flows of target information in the remote sensing space system Part 1. Task formalization

Starkov A.V., Emelyanov A.A., Grishantseva L.A., Zhukovskaya K.I., Morozov A.A., Trishin A.A.


The article is devoted to the formalization of the problem of distribution of target information flows during the operation of the ERS space system. It is proposed to consider the system as a complex, geographically-distributed information system, the main task of which is to implement a full service cycle, starting with the formation of an application and ending with the provision of a finished thematic product. The decomposition of the ERS space system as a complex information organizational and technical system was carried out, the system and consumer characteristics of its elements were determined. The possibility is substantiated to carry out an objective curtailment of system performance indicators and go to two particular ones that characterize the effectiveness of the target functioning of the system as a whole: the promptness (time) of fulfilling consumer requests for a finished thematic product and the cost of the finished thematic product. A general methodological approach to solving the technical problem is proposed. The result is a formal presentation of the task of distributing the streams of target information during the operation of the ERS space system as a sequence of the following operations: formation of an application; determination of the list of requests to the system required to complete the application; determining the processes and the sequence of their execution that will process the corresponding requests; optimization of the time distribution of processes among the elements of the system, taking into account the selected performance indicators and existing limitations.

RUDN Journal of Engineering Research. 2021;22(1):54-64
pages 54-64 views

Designing of the blades of aircraft propellers by the finite element method, taking into account the strength of structure

Agapov V.P., Aidemirov K.R.


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.

RUDN Journal of Engineering Research. 2021;22(1):65-71
pages 65-71 views

Method for determining the optimal parameters of the chain transmission, taking into account the design of the drive chain

Belousov Y.V.


Goal . Develop the design of the drive plate chain and methods for determining the optimal parameters of the chain transmission. Methods. Analysis of the designs of standard drive bushing and roller chains, as well as the drive plate chain with internal engagement. Determination of ways to increase the durability of these chains and chain gears from the condition of ensuring the wear resistance of their hinges and increasing their technical and economic indicators. Results . The analysis of designs of standard drive bushing-roller chains and drive plate chains with internal gearing is performed. A promising design of the drive plate chain has been developed. The optimization of transmission parameters, both with standard chains, and with the chain proposed by the authors, providing an increase in their durability and efficiency. In this regard, a method has been developed for determining the greatest elongation of standard chain links, as well as the chain developed by the authors, from the condition of wear resistance of their hinges. A method for determining the optimal transmission ratio of these chain gears has also been developed. It is established that the gear ratio of the transmission with the drive plate chain developed by the authors is determined primarily by the accuracy of manufacturing its hinges. With sufficiently precise manufacturing of chain hinge parts, the gear ratio can be significantly increased, up to u=10 and higher. This will allow you to use gears equipped with this chain in drives with a large gear ratio.

RUDN Journal of Engineering Research. 2021;22(1):72-83
pages 72-83 views

Pseudospheric shells in the construction

Gil-oulbé M., Ndomilep I.J., Ngandu P.


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.

RUDN Journal of Engineering Research. 2021;22(1):84-99
pages 84-99 views

Analytical review of underground equipment of water impact operation for well development

Yushin E.S.


Rational indicators for the development of oil and gas fields are related to the systemic maintenance of a given level of perfection of formation opening in bottomhole zones of producing or injection wells. This need arises with the colmatation of the natural collector by mechanical, asphalt and tar-paraffinic particles, leading to a decrease in productivity, acceptance of wells and the need to restore the inflow by methods of artificial action on the bottomhole formation zone. Analysis of the effectiveness of the application of various methods of stimulating the flow of reservoir products in the fields of the Timan-Pechora oil and gas province (based on field data) allowed to argue the success of using hydraulic fracturing, thermogas chemical, and shock-depressive effects on the bottomhole formation zone. The prospect of the development of technical means for impact-depressive (implosion) impact on the bottomhole formation zone favorably distinguished by simplicity, cheapness, manufacturability and accessibility is shown. The designs of implosion hydrogenerators of single and multiple pressure are analyzed, shortcomings of technical devices are identified and ways of improving mechanisms are outlined. The results of effective application of various downhole generator devices for increasing productivity and well acceptance are presented.

RUDN Journal of Engineering Research. 2021;22(1):100-112
pages 100-112 views

Submarine pipeline stability under currents and waves action

Mordvintsev K.P., Gogin A.G., Korneeva E.M.


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.

RUDN Journal of Engineering Research. 2021;22(1):113-121
pages 113-121 views

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