Discrete and Continuous Models and Applied Computational Science

We describe introduced in the journal the rubric system.

This article continues the cycle of works by the authors devoted to the problem of the age of information (AoI), a metric used in information systems for monitoring and managing remote sources of information from the control center. The theoretical analysis of information transmission systems requires a quantitative assessment of the “freshness” of information delivered to the control center. The process of transferring information from peripheral sources to the center is usually modeled using queuing systems. In this paper, a queuing system with phase-type distributions is used to estimate the maximum value of the information age, called the peak age. This takes into account the special requirement of the transmission protocol, which consists in the fact that information enters the system in groups of random size. For this case, an expression is obtained for the Laplace-Stieltjes transformation of the stationary distribution function of the peak age of information and its average value. Based on the results of analytical modeling, a numerical study of the dependence of the average value of the peak age of information on the system load was carried out. The correctness of the expressions obtained was verified by comparing the analytical results with the results of simulation modeling.

Chronic non-communicable diseases account for more than 70% of global mortality statistics. The main share is made up of diseases of the cardiovascular system. Adequate preventive measures-impact on controllable and conditionally controllable risk factors-can reduce the contribution of these diseases to the structure of mortality. A significant effect can be achieved with an adequately selected level of physical activity, but doctors do not always recommend specific actions to patients. This article describes a prototype of a cognitive assistant for constructing personalized plans for therapeutic physical exercises for relatively healthy people and people suffering from cardiovascular diseases. The developed system consists of two main components: a cardiovascular risk assessment module and an exercise planning module. The risk assessment module consists of a knowledge base and an argumentative reasoning algorithm. Its task is to identify risk factors and levels, which is dual in nature: in the case of monitoring a relatively healthy user, the risk of developing cardiovascular disease is assessed, while in the case of interaction of the system with a user with cardiovascular disease, the risk of complications of a chronic form is assessed-development of a cardiovascular event. The exercise planning module includes an exercise database and a scheduler algorithm. The planning algorithm selects optimal therapeutic physical exercises according to optimal criteria, in order to form a plan that will not harm the patient and will increase his physical performance. The developed mechanism allows you to create training scenarios for users with any level of initial training, taking into account the available sports equipment, the preferred location for training (home, street, gym) and at any level of the cardiovascular continuum.

Our group has been investigating kinetic models for quite a long time. The structure of classical kinetic models is described by rather simple assumptions about the interaction of the entities under study. Also, the construction of kinetic equations (both stochastic and deterministic) is based on simple sequential steps. However, in each step, the researcher must manipulate a large number of elements. And once the differential equations are obtained, the problem of solving or investigating them arises. The use of symbolic-numeric approach methodology is naturally directed. When the input is an information model of the system under study, represented in some diagrammatic form. And as a result, we obtain systems of differential equations (preferably, in all possible variants). Then, as part of this process, we can investigate the resulting equations (by a variety of methods). We have previously taken several steps in this direction, but we found the results somewhat unsatisfactory. At the moment we have settled on the package Catalyst.jl, which belongs to the Julia language ecosystem. The authors of the package declare its relevance to the field of chemical kinetics. Whether it is possible to study more complex systems with this package, we cannot say. Therefore, we decided to investigate the possibility of using this package for our models to begin with standard problems of chemical kinetics. As a result, we can summarize that this package seems to us to be the best solution for the symbolic-numerical study of chemical kinetics problems.

The filtration process is studied for a popular class of filters with radial cartridges that proved their high effectiveness in purification of water. The mass balance equation for radial flows in porous media is obtained by using the lattice approximation method, the transverse diffusion process being taken into account. The Euler dynamical equations are modified by including the Darcy force proportional to the velocity of the filtration flow. The system of equations is written for the stationary axially symmetric radial flow and solved by the perturbation method, if the vertical velocity is supposed to be small.

A new method for the correct identification of various complex structural elements of ancient hieroglyphs is described. The method is based on photometry of the studied surface of the ancient artifacts. The obtained data are converted into digital form in order to determine the characteristics and parameters characterizing the properties of the investigated artifact surface. Digitized data is processed in various graphic applications, including those working with vector images. Several control experiments were also carried out. In particular, the corresponding statistical characteristics and parameters of the studied artifact surface profiles were determined. The data obtained made it possible to unambiguously detect the ancient hieroglyphs on the artifact surface and determine their number. Described method of studying ancient artifacts makes it possible to obtain sufficiently reliable results that will undoubtedly be useful and promising in the study of ancient hieroglyphic signs. Our research method is characterized as: non-contact, informative, and sensitive. This testifies to its importance and prospects in the study of similar ancient artifacts.