ISSN 0869-6632 (Print)
ISSN 2542-1905 (Online)


Nonlinear systems

Human brain state monitoring in perceptual decision-making tasks

The purpose of this review is to observe the current state of research on sensorimotor integration in the human brain during visual perception and subsequent decision-making under conditions of ambiguous information. Methods. This review examines the approaches of time-frequency wavelet analysis for brain activity when performing perceptual tasks, as well as the possibility of using such methods in the tasks of constructing brain – computer interfaces. Results.

Modeling of wave patterns at the combustion front

In experimental studies of the propagation of combustion waves in gaseous media, it was found that, under certain conditions, autowave – spiral or target – patterns appear at the wave front. The purpose of the present study is to propose a mathematical model that can explain this phenomenon based on the known chemical kinetics of hydrogen combustion. Model. The original detailed model was first reduced to four equations that adequately describe the propagation of the combustion wave.

Mathematical model and dynamical analysis of the human equilibrium seeking training

The purpose of this work is to determine the ability of the partial directed coherence method to identify the
directed interaction between nonlinear systems correctly in presence of nonlinear couplings between systems, as well as
in the case when the measured signals are generated by objects of high dimension. The another purpose is to determine
the dependence of the coupling estimation results on the parameters: series length, sampling rate, model dimension and the

Non-contact atomic force microscope: Modeling and simulation using van der Pol averaging method

Topic and aim. One of the tools which are extremely useful and valuable for creating a topography of surfaces, measuring forces, and manipulating material with nano-meter-scale features is the Atomic force microscope (AFM). Since it can create the image of the surface object in different mediums at the nano-scale, AFM can be used in a wide variety of applications and industries. This work aimed at creating the mathematical model of the non-contact atomic force microscope. Models and Methods.

Non-Contact Atomic Force Microscope: Modeling and Simulation using Van der Pol Averaging Method

One of the tools which are extremely useful and valuable for creating a topography of surfaces, measuring forces, and manipulating material with nano-meter-scale features is the Atomic force microscope (AFM). Since it can create the image of the surface object in different mediums at the nano-scale, AFM can be used in a wide variety of applications and industries. The lumped parameter model of the atomic force microscope in the non-contact operation mode is utilized to make the mathematical model of the micro cantilever of the AFM in this article.

Waves of strain in two coaxial cubically nonlinear cylindrical shells with a viscous fluid between them

Subject of the study. Longitudinal deformation waves are investigated in physically nonlinear coaxial elastic shells with a viscous incompressible fluid between its. There are taken into account effect on the amplitude and speed of inertia wave of the fluid and the environment, and as well as the damping properties of the structural materials, from which the waveguides are made.

Multistability and memory effects in dynamical system with cosymmetric potential

The purpose of present study is the analysis of strong multistability in a dynamical system with cosymmetry. We study the dynamics and realization of steady-states in a mechanical system with two degrees of freedom. The minimum potential energy of the system is achieved on a curve in the form of an ellipse, which gives rise to a continuum family of equilibria and strong multistability. This problem belongs to the class of dynamical systems with cosymmetry. Methods.

Effect of nonlinearity on coupling estimations between oscillators using partial directed coherence approach

The purpose of this work is to determine the ability of the partial directed coherence method to identify directed interactions between nonlinear systems correctly in presence of nonlinear couplings between systems, as well as in the
case of measured signals generated by objects of high dimension. The other purpose is to determine the dependence of the coupling estimation results on the parameters: series length, sampling rate, model dimension and coupling architecture.

Аnalytical research of nonlinear properties of ferroelectrics

This paper describes a method to obtain an analytical expression for the nonlinear dependence of the ferroelectric polarization on the external electric field. To find analytical dependence, used a special Kml-function of second order. Listed structure built of series and groups  of series representing Kml-function at any point in the complex plane. Analyzed domain of  convergence of series , received as a boundary condition. To show the application of the method, as  an example used a ferroelectric polymer polyvinylidene fluoride (PVDF–TrFE ).

Diagnostics and correction of systematic error while estimating transfer entropy with k-nearest neighbours method

Transfer entropy is widely used to detect the directed coupling in oscillatory systems from their observed time series. The systematic error is detected, while estimating transfer entropy between nonlinear systems with K-nearest neighbours method. The way to minimize this error is suggested: the error is decreasing with increase of the neighbour number. The possibility to detect the systematic error is shown using two sets of measured data. The achieved results make possible to rise the method sensitivity and specificity for weakly coupled nonlinear systems.  

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