Izvestiya of Saratov University.
ISSN 1816-9791 (Print)
ISSN 2541-9005 (Online)

Computer Sciences

Numerical simulation of oil production using surfactant-polymer flooding

The paper is devoted to the numerical modeling of oil field development using enhanced oil recovery technologies based on surfactant-polymer flooding. The proposed approach is aimed at assessing the possible efficiency and advisability of using surfactant-polymer flooding at the later stages of real fields development.

The concept of information packet interaction in a multilevel system of digital twins

An approach to organizing information interaction in a multilevel system of digital twins is considered. The unit of inter-level information exchange is a software structure of a special type — a package, built on the principle of organizing messages in HTTP(s)-protocols. Directly, the metadata of the data source is placed in the header of the package and allows identification / authentication of the corresponding resources as data arrives.

Wavelet p-analogs of the discrete Haar transform

Two $p$-analogs (for $p>2$) of the discrete version of the Haar system in vector symbolism are proposed and fast algorithms are constructed based on them. The main wavelet principles for constructing these Haar-like systems are proposed, such as the presence of several parent functions, $p$-ary dilations and shifts. One of the systems retains an orthogonality property. The calculation procedure has been simplified for another almost orthogonal system.

The key exchange protocol based on non-commutative elements of Clifford algebra

Many of the asymmetric cryptography protocols are based on operations performed on commutative algebraic structures, which are vulnerable to quantum attacks. The development of algorithms in non-commutative structures makes it possible to strengthen these protocols. Cryptography is a branch of mathematics that solves the problem of transmitting information through unsafe channels. For this, information is encrypted, so it cannot be used without first decrypting it.

The search for minimal edge 1-extension of an undirected colored graph

Let $G=(V, \alpha, f)$ be a colored graph with a coloring function $f$ defined on its vertices set $V$. Colored graph $G^*$ is an edge $1$-extension of a colored graph $G$ if $G$ could be included into each subgraph taking into consideration the colors. These subgraphs could be built from $G^*$ by removing one of the graph's edges. Let colored edge $1$-extension $G^*$ be minimal if $G^*$ has as many vertices as the original graph $G$ and it has the minimal number of edges among all edge $1$-extensions of graph $G$.

Modeling the reliability of the onboard equipment of a mobile robot

Mobile robots with complex onboard equipment are investigated in this article. It is shown that their onboard equipment, for providing the required reliability parameters, must have fault-tolerant properties. For designing such equipment it is necessary to have an adequate model of reliability parameters evaluation. The approach, linked to the creation of the model, based on parallel semi-Markov process apparatus, is considered. At the first stage of modeling, the lifetime of the single block in a complex fault-recovery cycle is determined.

Resource optimization in management of technical maintenance of automation and remote control systems

The article considers the topical problem of resource optimization during the maintenance process of technical systems. In order to illustrate the methodology (URRAN) developed by Russian Railways JSC to solve this problem, automation and remote control systems are used as an example. Due to  a total lack of resources and the infinite needs, the company  faced  the challenge of improving the efficiency of maintenance and repair of railway automation and remote control systems.

Construction of 3D solid vertebral models using convolutional neural networks

The quality of solving the problem of biomechanical modeling largely depends on the created solid-state model of the biological object under study. Building a model based on computed tomography data for a particular patient is possible both in manual mode (software packages for processing medical images) and using automated tools for building a model (image segmentation), which significantly speeds up the process of creating a solid model, in contrast to the manual mode.

Generation of colored graphs with isomorphism rejection

In the article we consider graphs whose vertices or edges are colored in a given number of colors — vertex and edge colorings. The study of colorings of graphs began in the middle of the 19th century, but the main attention is paid to proper colorings, in which the restriction applies that the colors of adjacent vertices or edges must be different. This paper considers colorings of graphs without any restrictions. We study the problem of generating all non-isomorphic vertex and edge $k$-colorings of a given graph without direct checking for isomorphism.

Mathematical and computer simulation of the electrophysical properties of a multicellular structure exposed to nanosecond electrical pulses

The article presents mathematical and computer models which allow to study the electrophysical properties (permittivity, impedance) of a multicellular structure exposed to nanosecond electrical pulses. The paper proposes a simulation approach that includes complex use of the classical theory of describing the electrodynamic properties of dispersed systems and the effective medium theory. We describe cell geometry using Gielis equations, which allow us to take account of the irregular shapes of cell membranes.