Vol 9, No 1 (2022)

Task. The purpose of writing this article is to improve the security of information in information systems. Model. The article proposes an improved method for analytical modeling of the process of spreading virus software in information systems in relation to the features of a special class of attacks implemented by the family of virus software - ransomware. Conclusions. The proposed method makes it possible to analytically calculate the intensity of infection of hosts of a protected information system with various types of virus software and use the obtained characteristics as initial data for the final assessment of the information security risk on the protected informatization object. Value. Modeling in the environment of the mathematical package PTC Mathcad Prime 7 showed the applicability of the proposed approach for analytical threat modeling.

The article continues studies of bijective mapping determined by quasi-hadamard matrices started in work [8]. It is proved that for different quasi-hadamard martices there are different mappings. All quasi-hadamard matrices of orders 4 and 8 are also described.

Nowadays hashtags are an important mechanism of semantic navigation in social media. In this study, we consider the solution of the problem of building associative series of hashtags for one of the largest social networks. These series should meet two criteria: they should be short and shouldn’t have wide semantic gaps between sequential hashtags. An algorithm that allows us to create an associative series of hashtags could be used to increase the quantity of hashtags in posts, which will facilitate semantic navigation through posts in a social network. The paper proposes a formal definition of the semantic path building problem as a multicriteria optimization problem on the co-occurrence network of hashtags in posts. First, we built a co-occurrence network for hashtags from a big dataset of messages from Instagram. Then, we develop a combined optimization function for both criteria from the semantic path building problem. For measuring semantic similarity between hashtags, we use a metric based on the word2vec embeddings of hashtags. Using empirical paths obtained with various algorithms, we tune the parameters of a generalized optimization function that can be used to construct semantic paths using Dijkstra’s pathfinding or special greedy algorithms.

The article considers a new type of matrices that define bijective coordinate-threshold mappings - (n - 2)- structured matrices. It is proved that different matrices define different transformations, all (n - 2)-structured matrices of order 4 are described. For an arbitrary n ∈ ℕ, n classes of (n - 2)-structured matrices are specified, it is proved that the transformations specified by these matrices generate the group S2 S2n - 1. It is shown that the matrix transposed to the given one generates the inverse transformation.

Usage of question-answering systems has become a popular way to access knowledge bases that contain a large number of facts from different domains. Large-scale universal knowledge bases with open access, such as Wikidata, contain huge collections of facts. Although those bases cover the most significant part of the accumulated humankind knowledge, there are a number of reasons why their direct usage in question-answering systems can be less preferable than the creation of specialized domain knowledge bases based on them. This paper presents a technology for building a domain knowledge base for a dialogue system based on domain boundaries detection from an open large-scale universal knowledge base. It is based on a multi-step process of analyzing a large number of free-form questions on a given subject area that were collected using a crowdsourcing platform. The technology includes the correction of the original knowledge base ontological structure and its filling with additional content. The proposed technology is invariant to the original knowledge base and the modeling subject area. We tested it on the Wikidata knowledge base and six subject areas.

The results of comparative tests of a polyethylene film and a film-ceramic composite of sun-dried grapes are presented. A film-ceramic composite based on polyethylene and functional ceramics allows deeper and faster drying of products compared to conventional polyethylene film. The film-ceramic composite, other things being equal, makes it possible to achieve a commercial degree of drying of grapes almost 1.5 times faster. When drying grapes, the faster drying rate is most likely determined by the deeper penetration of the pulsed radiation generated by functional ceramics. Conventional polyethylene film without functional ceramics completely degraded in about 2 months. The film-ceramic composite did not change at all during the year.

As we know, one of the most important and important issues in the implementation of technological processes is the implementation of accurate and correct temperature measurements. During the research, attention was paid to the measurement errors in temperature measurements of technological processes using thermocouples and methods of minimizing those errors. In addition, errors in thermocouple temperature measurements were briefly discussed, and for temperatures limited to a certain range, the T-type thermocouple achieved several times less error than the allowable error specified in the normative documents. It is known that when describing thermocouples in the technical literature, first of all, industrial devices with high temperature coefficient and medium class accuracy are considered. Also, as we know, in domestic applications, the temperature difference between the measurement and the reference node varies mainly within the minimum threshold range. Therefore, if the main source of error is the internal reference temperature compensation in the measuring instrument, it is almost impossible to determine the proportion of errors due to the thermocouple itself. The study found that the measurement error can be significantly reduced when determining the temperature of technological processes using an external reference node. At the same time, since the special application of temperature measurements of technological processes covers the measurement of indoor and outdoor temperatures, the errors due to the effect of radiation on the sensor from the surrounding surfaces are many times higher than the allowable error. For this reason, tools have been proposed to assess the radiation effects on typical thermocouples, along with proposals for modification of thermocouple sensors to reduce the potential radiation exposure and thus increase measurement accuracy.