Статьи

The paper places an emphasis on the fact that many publications on complex reliability assessment of electric power and fuel systems do not always substantiate the application of various methods. We address the “system”, “nodal”, and “estimation” approaches to assess the reliability of electric power systems, given reliable fuel supply to power plants. These approaches are accompanied by an analysis of their correspondence to the objectives and goals of the study, as well as an analysis of the validity of their application in terms of the obtained result accuracy, research time, complexity of search for and preparation of the input data and forms of their representation in a model. All the approaches were tested in case studies. The nodal and system approaches were tested on a conventional power system, while the estimation approach was tested on design diagrams of the gas and electric power systems of the Northwestern Federal District of the Russian Federation

The problem of finding equilibrium configurations of one-component charged particles, induced by external electrostatic fields in planar systems, is a subject of active studies in fundamental as well in experimental investigations. In this paper the results of numerical analysis of the equilibrium configurations of charged particles (electrons), confined in a circular region by an infinite external potential at its boundary are presented. Equilibrium configurations with minimal energy are searched by means of special calculation scheme. This computational scheme consists of the following steps. First, the configuration of the system with the energy as close as possible to the expected energy value in the ground equilibrium state is found using a model of stable configurations. Next, classical Newtonian molecular dynamics is used using viscous friction to bring the system into equilibrium with a minimum energy. With a sufficient number of runs, we obtain a stable configuration with an energy value as close as possible to the global minimum energy value for the ground stable state for a given number of particles. Our results demonstrate a significant efficiency of using the method of classical molecular dynamics (MD) when using the interpolation formulas in comparison with algorithms based on Monte Carlo methods and global optimization. This approach makes it possible to significantly increase the speed at which an equilibrium configuration is reached for an arbitrarily chosen number of particles compared to the Metropolis annealing simulation algorithm and other algorithms based on global optimization methods.

The analysis of trajectory dynamics and the solution of optimization problems using computer methods are relevant areas of research in dynamic population-migration models. In this paper, four-dimensional dynamic models describing the processes of competition and migration in ecosystems are studied. Firstly, we consider a modification of the “two competitors—two migration areas” model, which takes into account uniform intraspecific and interspecific competition in two populations as well as non-uniform bidirectional migration in both populations. Secondly, we consider a modification of the “two competitors—two migration areas” model, in which intraspecific competition is uniform and interspecific competition and bidirectional migration are non-uniform. For these two types of models, the study is carried out taking into account the variability of parameters. The problems of searching for model parameters based on the implementation of two optimality criteria are solved. The first criterion of optimality is associated with the fulfillment of such a condition for the coexistence of populations, which in mathematical form is the integral maximization of the functions product characterizing the populations densities. The second criterion of optimality involves checking the assumption of the such a four-dimensional positive vector existence, which will be a state of equilibrium. The algorithms developed on the basis of the first and second optimality criteria using the differential evolution method result in optimal sets of parameters for the studied population-migration models. The obtained sets of parameters are used to find positive equilibrium states and analyze trajectory dynamics. Using the method of constructing self-consistent one-step models and an automated stochastization procedure, the transition to the stochastic case is performed. The structural description and the possibility of analyzing two types of population-migration stochastic models are provided by obtaining Fokker–Planck equations and Langevin equations with corresponding coefficients. Algorithms for generating trajectories of the Wiener process, multipoint distributions and modifications of the Runge–Kutta method are used. A series of computational experiments is carried out using a specialized software package whose capabilities allow for the construction and analysis of dynamic models of high dimension, taking into account the evaluation of the stochastics influence. The trajectory dynamics of two types of population-migration models are investigated, and a comparative analysis of the results is carried out both in the deterministic and stochastic cases. The results can be used in the modeling and optimization of dynamic models in natural science.

This work is the second part of a large bibliographic review of active queue management algorithms of the Random Early Detection (RED) family, presented in the scientific press from 1993 to 2023. This part provides data on algorithms published from 2006 to 2015.

The article describes a method for calculating interpolation coefficients of expansion using Chebyshev polynomials. The method is valid when the desired function is bounded and has a finite number of maxima and minima in a finite domain of interpolation. The essence of the method is that the interpolated desired function can be represented as an expansion in Chebyshev polynomials; then the expansion coefficients are determined using the collocation method by reducing the problem to solving a well-conditioned system of linear algebraic equations for the required coefficients. Using the well-known useful properties of Chebyshev polynomials can significantly simplify the solution of the problem of function interpolation. A technique using the Clenshaw algorithm for summing the series and determining the expansion coefficients of the interpolated function, based on the discrete orthogonality of Chebyshev polynomials of the 1st kind, is outlined.

This work is the first part of a large bibliographic review of active queue management algorithms of the Random Early Detection (RED) family, presented in the scientific press from 1993 to 2023. The third part will provide data on algorithms published from 2016 to 2023.

This paper concerns Corporate Social Responsibility (CSR) employer branding and its impact on employee attraction and retention, seeking to systematize academic knowledge about their interconnections and links to other important management issues. We made a systematic literature review focusing on empirical papers published in academic journals over the last 10 years, which enabled us to identify the directions of contemporary research, commonly used methodologies and contexts explored. It shows that CSR initiatives are increasingly recognized as a critical dimension of employer branding. Alignment of CSR practices and employer branding strategies is essential for attracting top talent. We also observed a strong link between CSR and employer attractiveness, career development, organizational identification, corporate reputation and person-organization fit, which underscores the multifaceted nature of CSR employer branding. It has been found that CSR researchers predominantly use quantitative methodologies in their studies and tend to explore the firms that work in the IT industry. The paper discusses the current state of CSR employer branding research and outlines possible avenues for future studies.

In 2007, the world reached a pivotal moment in the ongoing process of urbanization, with the global urban population surpassing the rural population for the first time. Africa is the only continent where this process has not yet been completed. According to UN projections, it is expected to occur no earlier than the second third of the 21st century. Africa, however, is very diverse in this regard: in some countries, the majority of the population has long been urban, while in others, most of the population are still living in rural areas.

We consider finite deterministic automata such that their alphabets consist of exactly one letter of defect 1 and a set of permutations of the state set. We study under which conditions such an automaton is completely reachable. We focus our attention on the case when the set of permutations generates a transitive imprimitive group.

Lack of physical activity has emerged as a considerable public health concern worldwide. Recent advancements in fitness technologies in the past ten years provide novel prospects to encourage physical activity and combat increasing levels of sedentary lifestyles, obesity, and related chronic illnesses. This paper examines the empirical evidence on the potential advantages, restrictions, and optimal practices pertaining to three predominant trends in fitness technology: wearable gadgets, artificial intelligence platforms, and social media. Wearable activity monitors demonstrate potential to boost physical activity engagement and enhance certain health indicators, however their precision and long-standing compliance appear inconsistent. Preliminary evidence indicates artificial intelligence holds promise for individualized fitness instruction and tracking via conversational agents, albeit necessitating further substantiation. Social media and fitness influencers can galvanize their followers, but concerns remain regarding promotion of unrealistic body ideals. Overall, these technologies exhibit promise to facilitate more accessible, personalized and social fitness participation if consciously implemented based on scientific findings. Further interdisciplinary investigation is imperative to optimize these burgeoning innovations equitably and ethically, so as to best promote global population health and wellness.

Статья посвящена сравнительному анализу трех ключевых парадигм машинного обучения (МО): обучение с учителем, обучение без учителя, обучение с подкреплением – наряду с оценкой популярных фреймворков МО, таких как TensorFlow, PyTorch и Scikit-learn. В исследовании были изучены основные различия, преимущества и ограничения подходов МО, особое внимание уделялось таким факторам, как: вычислительные затраты, масштабируемость и простота реализации. Рассмотрены аспекты интерпретируемости моделей МО и проанализированы вычислительные ресурсы, необходимые для их работы, включая нагрузку на центральный процессор и оперативную память. Результаты дают необходимую информацию о том, как различные методологии и технологии МО формируют реальные приложения и влияют на практическое принятие решений в системах, управляемых искусственным интеллектом.

Writing is a key act in the process of foreign language acquisition. The ability to write properly and accurately is essential for effective communication and critical for human employment. Semantically accurate and grammatically proper writing is of paramount importance especially for students in higher educational institutions. Hence, the present research tends to examine the mistakes made by second language learners in writing essays and proposes recommendations how to improve the English writing skills of the Chinese students. The goal of the research is to reveal common and contrastive features of language errors and help Chinese students to improve their grammatical competences. In order to achieve the above-mentioned goals, the following tasks have been set forth: to discuss and specify the characteristic features of common errors made by Chinese college students; to study different types of errors in writing samples provided by Jiangxi Tellhow Animation Vocational College students; to analyze the possible transformative teaching tendencies and methods that will improve second language learners’ writings abilities. The practical significance of the paper is deeply supported by the applicability of its content in education. The methods of inquiry, comparative analysis, component analysis, observation, data collection, etc., have been applied to the research to fulfil the tasks of this research.