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## Nonlinear dynamics of an expert,s thinking and algorithms of his professional knowledge expansion by example of medical problems

The process of a problem area experts knowledge acquisition is considered from a nonlinear dynamics positions. Stages and types of acquired knowledge are marked out; the role of an intuitive thinking in decision process concerning complex objects is defined. The role of intelligent data analysis methods in new knowledge forming processes is defined. The result of a developed «Semantic computer knowledge base analysis» algorithm is given on an example of the concrete medical problem.

## Autonomous system generating hyperbolic chaos: circuit simulation and experiment

We consider an electronic device, which represents an autonomous dynamical system with hyperbolic attractor of the Smale–Williams type in the Poincare map. Simulation ? of chaotic dynamics in the software environment Multisim has been undertaken. The generator of hyperbolic chaos is implemented as a laboratory model; its experimental investigation is carried out, and good compliance with the observed dynamics in the numerical and circuit simulation has been demonstrated.

## Doubling and destruction of the tri-frequencies torus in the nonlinear oscillator under quasi-periodic exitation: experiment

In present paper nonlinear oscillator driving by external force in a form of three harmonic signals with irrational ratios of the frequencies and the map of various dynamical regimes on the parameter plane are presented. The feature of tri-frequencies torus doubling and destruction are investigated.

## Bifurcations and transitions to chaos in superlattice coupled to external resonator

In this letter we study nonlinear dynamics and transition to chaos in semiconductor superlattice coupled to external linear resonator. We have shown that such system demonstrates chaotic dynamics in wide range of supply voltage, whereas in autonomous superlattice only periodical dynamics exists. Revealed that transition to chaos in system goes through intermittency.

## Formation of a multi-domain spatial structure in gaas gunn diode as a nonlinear phenomenon

Experimental studies of stationary distributions of the electric ?eld intensity and the concentration of charge carriers in the Gunn diode have been provided by using near-?eld microwave microscope. The numerical computer calculation of these quantities based on the dependence of electrons mobility and di?usion coe?cient on the electric ?eld has been carried out. The existence of a multidomain mode of Gunn diodes has been found experimentally and con?rmed theoretically.

## The role of oxygen in briggs–rauscher autooscillating reaction

It is description of the way in which chemical environment of Briggs–Rauscher autooscillating reaction a?ects characteristics of oscillations. It has been ascertained that variations of the iodide complexes concentrations perhaps occurs due to increases of oxygen concentration in media and intermediate’s concentration ?uctuation. In?uence was investigated one of the basic natural oxidizing agent oxygen and it radical forms on autocooperative mechanisms of Briggs–Rauscher reaction.

## Adaptive control signals of a mismatch in cognitive processes: the role of the endogenous opioid system

In the work we consider the classic cyclic schemes for the construction of cognitive processes. Based on neurobiological data we indicate the need to introduce a special mechanism for adaptive control signals of a mismatch in cognitive processes at the stage preceeding the decision point. Endogenous opioid system can be considered one of the major neurochemical candidates for such «breakers». This system provides the suppression of signals about a mismatch between current and target states of the cognitive system.

## Sequential activity in neuronal ensembles with excitatory couplings

A new model of neurons like elements is suggested in the paper. The model is based on the generalized Lottka–Volterra model with excitatory coupling. The study is motivated by the fact that the excitatory couplings are the dominating type of interactions between neurons in the human brain. It is shown in the paper that there are two regimes exist in such ensemble of oscillators in dependence on the coupling between the elements: the regime with stable heteroclinical cycle and the regime with stable limit cycle.

## Problems of deterministic chaos theory in a. F. Goloubentsev’s works

A short review of contribution to the deterministic chaos theory, that had been made by professor Alexander F. Goloubentsev (Saratov University), is given.

## Two lectures about the two ways of symmetry investigation

These lectures were delivered to the high school students at the School – seminar «Nonlinear Days for Youth in Saratov – 2012» in October 2012. They present the two ways of historical investigation of symmetry. The ?rst way is self-similarity, i.e. invariance at dimension scale changing. In a more general way the term «scaling» is used, meaning the existence of power-law correlation between some variable and variables x1, ...xn: y = Ax?1...x?n1 (self-similarity) appearing in various ?elds of science and culture. G.I.