The article presents the IntvalPy library which implements interval computations in Python. Unlike other existing interval libraries, IntvalPy allows one to work with both classical interval arithmetic and complete Kaucher interval arithmetic. In addition, the library was developed taking into account the IEEE 1788-2015 standard for interval arithmetic on digital computers, which guarantees high accuracy of the results and compatibility with the other existing software products. The top-level functionality of the IntvalPy library implements state-of-the-art methods for recognizing and estimating solution sets for interval linear systems of equations, computing their formal solutions, and visualizing solution sets for interval equations and systems of equations. As an example of the library application, we solve the practically important problem of estimating the parameters of the electrochemical process of the formation of loose metal powder precipitates. Additionally, numerical computation was carried out, as well as qualitative comparisons with other interval libraries, in order to demonstrate the functionality and optimality of implemented interval classes.

The article presents an approach to modeling domain ontologies based on graph databases. Ontology is traditionally considered as a means of studying and formalizing the subject area. Based on ontologies, knowledge bases of information systems are formed, which can later be replenished and used to study certain applied aspects of the subject area. At the same time, with the development of NoSQL technologies and graph databases aimed at optimizing work with related data, it becomes possible to design a data warehouse without a strict pre-established domain model. Due to the obvious graph nature of ontologies, graph databases are a promising solution for storing and working with ontologies. However, with all the similarities, the ontology and data models used in graph DBMSs are not so easy to combine. The paper proposes an approach to the integration of ontological and graph models of knowledge representation and considers its application in creating a database for a prototype of a web ontology editor. Visual tools for editing ontologies are described, an algorithm for layer-by-layer rendering of a directed graph is given, a mechanism for generating dynamic forms for editing classes and ontology instances is described, and basic support for ontological design patterns is implemented.

The system approach to the study of organizational and technical systems, including organizational and technical elements and the interaction between them is used. The analysis of the literature on the investigated problem is carried out, the choice in favor of the conflict theory for the study of organizational-technical systems is made and the necessity of solving the scientific problem of clarifying the applicability of existing assessments of the conflicts of the system is determined. The hypothesis of the existence of a relationship between estimates of the conflict relations of elements and performance indicators of organizational-technical systems is considered.

By the example of a special purpose local communication network a mathematical model of conflict interactions is developed, utility functions of its elements are introduced, existing and new methods of evaluation of conflict relations of elements and the system as a whole are considered.

On the model of the considered local network we conduct a full-scale experiment to define the network performance (the ratio of the data transmission rate to the channel capacity, the central processor load, the ratio of the transmission time of a fixed amount of data to the minimum achievable with the use of the entire channel capacity) in various conditions of its operation, including the impact of negative factors. For each investigated state of the local network, we modify the mathematical model to calculate the values of the conflict relations of the elements and the system as a whole.

The choice of estimates of the conflict relations, potentially having connection with efficiency indicators is carried out. The correlation between the selected set of assessments of conflict relations and performance indicators is determined by methods of correlation analysis. As a result of the analysis, we singled out the estimates, which can be used to predict the degree of change in the conflicts of the system and its elements when modifying or changing the conditions of functioning.

The paper proposes a method of extracting the feature vector of images, which makes it possible to effectively detect the presence of hidden information in JPEG images embedded by various popular steganography tools. This method is based on the usage of the transition probability matrix. The essence of the method for extracting the feature vector of the image is to use the transition probability matrix and apply the image calibration method to improve the accuracy of steganalysis and reduce the number of false positives. For each image from the training and test sets a feature vector is found in this way, the number of elements is 324. Further, the models were trained on the training dataset by each of machine learning methods separately: decision trees with gradient boosting, linear models, k-nearest neighbors, support vector machines, neural networks, and artificial immune systems. To assess the capacity of the models the following metrics were used: accuracy, the rate of the false positive and false negative errors, and the confusion matrix. The results of classification by each of the above methods are given. For training and testing a dataset IStego100K was used, which consists of 208 thousand images of the same size 1024 x 1024 with different quality values in the range from 75 to 95. One of the J-UNIWARD, nsF5, and UERD steganography algorithms was used to embed a hidden message. As a result, we can observe that the proposed approach to extracting the feature vector makes it possible to detect the presence of hidden information embedded by non-adaptive steganography (Steghide, OutGuess and nsF5) in static JPEG images with high accuracy (more than 95%). However, for adaptive steganography methods (J-UNIWARD, UERD) the accuracy is less (about 50-60%).

This work is devoted to the study of the architecture of digital twins. Of course, it is inevitable that the technology of creating digital twins, borrowed from engineering, realizing specific turnovers, such as the need for massive costly software tools and highly qualified personnel, is clearly visible in the few examples of digital dual power systems. There is a lack of unambiguously interpreted data values in standard machine-readable formats, adequate mathematical models, and instrumentation. The article proposed approaches to overcome the shortcomings in the design and operation of digital twin systems.