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- Views (last year): 27.
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The 3rd BRICS Mathematics Conference
Computer Research and Modeling, 2019, v. 11, no. 6, pp. 1015-1016 -
Cellular automata review based on modern domestic publications
Computer Research and Modeling, 2019, v. 11, no. 1, pp. 9-57Views (last year): 58.The paper contains the analysis of the domestic publications issued in 2013–2017 years and devoted to cellular automata. The most of them concern on mathematical modeling. Scientometric schedules for 1990–2017 years have proved relevance of subject. The review allows to allocate the main personalities and the scientific directions/schools in modern Russian science, to reveal their originality or secondness in comparison with world science. Due to the authors choice of national publications basis instead of world, the paper claims the completeness and the fact is that about 200 items from the checked 526 references have an importance for science.
In the Annex to the review provides preliminary information about CA — the Game of Life, a theorem about gardens of Eden, elementary CAs (together with the diagram of de Brujin), block Margolus’s CAs, alternating CAs. Attention is paid to three important for modeling semantic traditions of von Neumann, Zuse and Zetlin, as well as to the relationship with the concepts of neural networks and Petri nets. It is allocated conditional 10 works, which should be familiar to any specialist in CA. Some important works of the 1990s and later are listed in the Introduction.
Then the crowd of publications is divided into categories: the modification of the CA and other network models (29 %), Mathematical properties of the CA and the connection with mathematics (5 %), Hardware implementation (3 %), Software implementation (5 %), Data Processing, recognition and Cryptography (8 %), Mechanics, physics and chemistry (20 %), Biology, ecology and medicine (15 %), Economics, urban studies and sociology (15 %). In parentheses the share of subjects in the array are indicated. There is an increase in publications on CA in the humanitarian sphere, as well as the emergence of hybrid approaches, leading away from the classic CA definition.
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Stationary states and bifurcations in a one-dimensional active medium of oscillators
Computer Research and Modeling, 2023, v. 15, no. 3, pp. 491-512This article presents the results of an analytical and computer study of the collective dynamic properties of a chain of self-oscillating systems (conditionally — oscillators). It is assumed that the couplings of individual elements of the chain are non-reciprocal, unidirectional. More precisely, it is assumed that each element of the chain is under the influence of the previous one, while the reverse reaction is absent (physically insignificant). This is the main feature of the chain. This system can be interpreted as an active discrete medium with unidirectional transfer, in particular, the transfer of a matter. Such chains can represent mathematical models of real systems having a lattice structure that occur in various fields of natural science and technology: physics, chemistry, biology, radio engineering, economics, etc. They can also represent models of technological and computational processes. Nonlinear self-oscillating systems (conditionally, oscillators) with a wide “spectrum” of potentially possible individual self-oscillations, from periodic to chaotic, were chosen as the “elements” of the lattice. This allows one to explore various dynamic modes of the chain from regular to chaotic, changing the parameters of the elements and not changing the nature of the elements themselves. The joint application of qualitative methods of the theory of dynamical systems and qualitative-numerical methods allows one to obtain a clear picture of all possible dynamic regimes of the chain. The conditions for the existence and stability of spatially-homogeneous dynamic regimes (deterministic and chaotic) of the chain are studied. The analytical results are illustrated by a numerical experiment. The dynamical regimes of the chain are studied under perturbations of parameters at its boundary. The possibility of controlling the dynamic regimes of the chain by turning on the necessary perturbation at the boundary is shown. Various cases of the dynamics of chains comprised of inhomogeneous (different in their parameters) elements are considered. The global chaotic synchronization (of all oscillators in the chain) is studied analytically and numerically.
Keywords: dynamical system, lattice, bifurcations, oscillator, phase space, dynamical chaos, synchronization. -
Semiclassical asymptotics of nonlinear Fokker–Plank equation for distributions of asset returns
Computer Research and Modeling, 2009, v. 1, no. 1, pp. 41-49Citations: 1 (RSCI).The semiclassical approximation method is applied for solution construction of the Fokker–Planck equation with quadratic nonlocal nonlinearity and various coefficients in models of asset returns estimation. Analitical expressions determining nonlinear evolution operator are obtained in semiclasical approximation.
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The present article sets out the scientific approach of Dmitry Sergeevich Chernavskii to the modelling of economic processes. It recounts the history of works of Dmitry Sergeyevich on the economic front, its milestones and achievements. One of the most important advances in the economic analysis was the prediction by a team of scientists headed by D. S. Chernavskii, the major crises that have occurred in our country over the last 20 years, namely, the default of 1998, the crisis of industrial production in the second half of the 2000s, the 2008 crisis and the ensuing recession. As an example, the dynamic analysis of the global macroeconomic processes shows the model of functioning of the dollar as the world currency. On this particular example shows the possibility of seigniorage due to the issue of the dollar and the calculated “window of opportunity” that allows you to issue dollars as the global currency, without prejudice to its own economy.
A model for the development of a closed society (without external economic relations) in the one-product approach is considered as an example of dynamic analysis of the economy of a separate state. The model is based on the principles of market economy, i.e. the dynamics of prices is determined by the balance of supply and demand. It is shown that in the general case, the state of market equilibrium is not unique. Several steady states with different levels of production and consumption are possible. Effect of addressed emission of money in underproductive state is considered. It is shown that, depending on its size it can lead to the transition to a highly productive condition, and just cause inflation without transition. The relationship of these results with the “Keynesian” and “monetarist” approaches is discussed.
Keywords: the economy, crises, dynamic analysis, dollar, seigniorage, mathematical model, emission, inflation, the digital economy.Views (last year): 5. Citations: 2 (RSCI). -
Mathematical modeling of the age groups of employed peoples by the example of the southern regions of the Russian Far East
Computer Research and Modeling, 2016, v. 8, no. 5, pp. 787-801Views (last year): 4. Citations: 3 (RSCI).The article focuses on a nonlinear mathematical model that describes the interaction of the different age groups of the employed population. The interactions are treated by analogy with population relationship (competition, discrimination, assistance, oppression, etc). Under interaction of peoples we mean the generalized social and economic mechanisms that cause related changes in the number of employees of different age groups. Three age groups of the employed population are considered. It is young specialists (15–29 years), workers with experience (30–49 years), the employees of pre-retirement and retirement age (50 and older). The estimation of model’s parameters for the southern regions of the Far Eastern Federal District (FEFD) is executed by statistical data. Analysis of model scenarios allows us to conclude the observed number fluctuations of the different ages employees on the background of a stable total employed population may be a consequence of complex interactions between these groups of peoples. Computational experiments with the obtained values of the parameters allowed us to calculate the rate of decline and the aging of the working population and to determine the nature of the interaction between the age groups of employees that are not directly as reflected in the statistics. It was found that in FEFD the employed of 50 years and older are discriminated against by the young workers under 29, employed up to 29 and 30–49 years are in a partnership. It is shown in most developed regions (Primorsky and Khabarovsk Krai) there is “uniform” competition among different age groups of the employed population. For Primorsky Krai we were able to identify the mixing effect dynamics. It is a typical situation for systems in a state of structural adjustment. This effect is reflected in the fact the long cycles of employed population form with a significant decrease in migration inflows of employees 30–49 years. Besides, the change of migration is accompanied by a change of interaction type — from employment discrimination by the oldest of middle generation to discrimination by the middle of older generation. In less developed regions (Amur, Magadan and Jewish Autonomous Regions) there are lower values of migration balance of almost all age groups and discrimination by young workers up 29 years of other age groups and employment discrimination 30–49 years of the older generation.
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Views (last year): 17.
In the article is carried out the analysis of historical process with the use of methods of synergetics (science about the nonlinear developing systems in nature and the society), developed in the works of D. S. Chernavskii in connection with to economic and social systems. It is shown that social self-organizing depending on conditions leads to the formation of both the societies with the strong internal competition (Y-structures) and cooperative type societies (X-structures). Y-structures are characteristic for the countries of the West, X-structure are characteristic for the countries of the East. It is shown that in XIX and in XX centuries occurred accelerated shaping and strengthening of Y-structures. However, at present world system entered into the period of serious structural changes in the economic, political, ideological spheres: the domination of Y-structures concludes. Are examined the possible ways of further development of the world system, connected with change in the regimes of self-organizing and limitation of internal competition. This passage will be prolonged and complex. Under these conditions it will objectively grow the value of the civilizational experience of Russia, on basis of which was formed combined type social system. It is shown that ultimately inevitable the passage from the present do-mination of Y-structures to the absolutely new global system, whose stability will be based on the new ideology, the new spirituality (i.e., new “conditional information” according D. S. Chernavskii), which makes a turn from the principles of competition to the principles of collaboration.
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The stabilizing role of fish population structure under the influence of fishery and random environment variations
Computer Research and Modeling, 2017, v. 9, no. 4, pp. 609-620Views (last year): 6. Citations: 2 (RSCI).We study the influence of fishery on a structured fish population under random changes of habitat conditions. The population parameters correspond to dominant pelagic fish species of Far-Eastern seas of the northwestern part of the Pacific Ocean (pollack, herring, sardine). Similar species inhabit various parts of the Word Ocean. The species body size distribution was chosen as a main population feature. This characteristic is easy to measure and adequately defines main specimen qualities such as age, maturity and other morphological and physiological peculiarities. Environmental fluctuations have a great influence on the individuals in early stages of development and have little influence on the vital activity of mature individuals. The fishery revenue was chosen as an optimality criterion. The main control characteristic is fishing effort. We have chosen quadratic dependence of fishing revenue on the fishing effort according to accepted economic ideas stating that the expenses grow with the production volume. The model study shows that the population structure ensures the increased population stability. The growth and drop out of the individuals’ due to natural mortality smoothens the oscillations of population density arising from the strong influence of the fluctuations of environment on young individuals. The smoothing part is played by diffusion component of the growth processes. The fishery in its turn smooths the fluctuations (including random fluctuations) of the environment and has a substantial impact upon the abundance of fry and the subsequent population dynamics. The optimal time-dependent fishing effort strategy was compared to stationary fishing effort strategy. It is shown that in the case of quickly changing habitat conditions and stochastic dynamics of population replenishment there exists a stationary fishing effort having approximately the same efficiency as an optimal time-dependent fishing effort. This means that a constant or weakly varying fishing effort can be very efficient strategy in terms of revenue.
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First-order optimization methods are workhorses in a wide range of modern applications in economics, physics, biology, machine learning, control, and other fields. Among other first-order methods accelerated and momentum ones obtain special attention because of their practical efficiency. The heavy-ball method (HB) is one of the first momentum methods. The method was proposed in 1964 and the first analysis was conducted for quadratic strongly convex functions. Since then a number of variations of HB have been proposed and analyzed. In particular, HB is known for its simplicity in implementation and its performance on nonconvex problems. However, as other momentum methods, it has nonmonotone behavior, and for optimal parameters, the method suffers from the so-called peak effect. To address this issue, in this paper, we consider an averaged version of the heavy-ball method (AHB). We show that for quadratic problems AHB has a smaller maximal deviation from the solution than HB. Moreover, for general convex and strongly convex functions, we prove non-accelerated rates of global convergence of AHB, its weighted version WAHB, and for AHB with restarts R-AHB. To the best of our knowledge, such guarantees for HB with averaging were not explicitly proven for strongly convex problems in the existing works. Finally, we conduct several numerical experiments on minimizing quadratic and nonquadratic functions to demonstrate the advantages of using averaging for HB. Moreover, we also tested one more modification of AHB called the tail-averaged heavy-ball method (TAHB). In the experiments, we observed that HB with a properly adjusted averaging scheme converges faster than HB without averaging and has smaller oscillations.
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