Authors
Perevaryukha A.
|
Degree
|
PhD in Technique, St. Petersburg Institute for Informatics and Automation of Russian Academy of Sciences |
|---|---|
|
E-mail
|
madelf@pisem.net |
|
Articles
|
Cognitive simulation in the analysis of structural interactions of environmental processes in Caspian seaEcological processes in the face of rapid changes in the environment as an object for the computer
simulation requires a flexible approach to the analysis. Article devoted to applications of the
conceptual structuring of ideas about the interaction natural and anthropogenous factors on the basis
of cognitive models. The formal analysis of pulses in the sign graph in the context of the situation
degradation bioresources of Caspian Sea has promoted the development of original hybrid dynamic
systems for modeling sturgeon fish reproduction. It is shown that the choice of the mathematical
approach to the description of the situation can be based on the results of cognitive analysis of the
ecological relationships. At the conclusion of results of computational studies should logically follow
the newly theoretical interpretation of the observed changes in behavior of models. Chosen structure
of the new models allows us to consider various scenarios of environmental emergencies. In cognitive
oriented graph possible to make hypotheses, but to assess the abrupt changes necessary to
investigate the nonlinear dynamics of the trajectory of some key characteristics, which for the Caspian
Sea is the effectiveness of fish spawning. In such models often arise bifurcations of attractors
with the appearance of cycles that effect on environmental implications.
Read more...
Dynamically overridden systems for modeling of the two population processes with threshold effectsWe have proposed a method for constructing dynamically redefined structures for the purpose of modeling abrupt changes in biological processes. The method provides for the analysis of scenarios with a control action, which is aimed at optimizing the profit from the exploitation of biological resources. The situations are described by three differential equations, which are numerically solved on adjacent time intervals. The state of the predicate set controls the selection of dynamically overridden coefficients. We carry out comparisons of all predicates on the basis of averaged individual indicators of generations. Threshold states in the dynamics of population size are a consequence of the selection of events as special nonequilibrium states that change the regulation algorithm. Our method makes it possible to implement dangerous qualitative changes in the scenarios of biological resource management, when the stable modes of their existence are suddenly lost. For practical problems, we have algorithmically implemented computational scenarios for two different processes such as the collapse of fish stocks under expert control of the fishery and a rapid outbreak of pests. The situation of the collapse of the fish population in the scenario with control develops in two stages and is a consequence of the experts 'desire to optimize the operation with uncertainty in an expert’s assessment of a state of a fishery. To confirm the relevance of our models, comparisons are made with the graphs of the development of the two real processes, as the spontaneous population explosion and the stock crisis during optimization of the sea cod fishery. Read more... Modeling a scenario of an extreme increase in infections after attenuation of waves of the oscillating SARS-CoV-2 epidemicAnalysis of epidemic processes is one of the oldest tasks for the application of modeling methods in the field of studying the state of society. Despite the availability of many approaches to the development of epidemic models, experts were unable to timely obtain an acceptable forecast for the ongoing spread of coronavirus in the winter of 2024. With new waves, the updated virus has returned once again after victory over the infection was declared. The possibilities and problems of office structures based on modifications of SIR models for a modern epidemic stage of a virus that continues to mutate are determined. The global dynamics of infections changed the oscillation mode twice: after the peak in the spring of 2022 and in the winter of 2024. After the global Omicron wave, local epidemics acquired an asynchronous character based on the formation and attenuation of a series of waves. The frequency of occurrence of individual infection peaks varied significantly across regions already in 2020. In some countries, frequent short waves of large amplitude developed. We classified the scenarios according to the characteristic features of their nonlinear dynamics. We proposed a method for modeling the sharp development of spread of the virus based on equations with threshold regulation functions that describe variants of the formation of outbreaks of infections and situational damping functions that determine the form of oscillating attenuation for the number of infections. The fading trend after primary wave in the model is interrupted by a mass infection event, which induces an outbreak of infections and then a new regime of fluctuation attenuation follows. Our computational experiment simulates the development of an extreme peak after the stage of attenuation of waves of a local epidemic as a bifurcation scenario for the reactivation of waves of the SARS-CoV-2 coronavirus activity, which is due to effect of a crowded disease. Read more... |
