Waves in the Skyrme--Faddeev model and integrable reductions

In the present article we show that the Skyrme--Faddeev model possesses nonlinear wave solutions, which can be expressed in terms of elliptic functions. The Whitham averaging method has been exploited in order to describe slow deformation of periodic wave states, leading to a quasi-linear system. The reduction to general hydrodynamic systems have been considered and it is compared with other integrable reductions of the system.Comment: 16 pages, 5 figure

Riding a Spiral Wave: Numerical Simulation of Spiral Waves in a Co-Moving Frame of Reference

We describe an approach to numerical simulation of spiral waves dynamics of large spatial extent, using small computational grids.Comment: 15 pages, 14 figures, as accepted by Phys Rev E 2010/03/2

A Numerical Method for Solving Linear–Quadratic Control Problems with Constraints

The paper is devoted to the optimal control problem for a linear system with integrally constrained control function. We study the problem of minimization of a linear terminal cost with terminal constraints given by a set of linear inequalities. For the solution of this problem we propose two-stage numerical algorithm, which is based on construction of the reachable set of the system. At the first stage we find a solution to finite–dimensional optimization problem with a linear objective function and linear and quadratic constraints. At the second stage we solve a standard linear–quadratic control problem, which admits a simple and effective solution.The research is supported by Russian Science Foundation, project no. 16–11–10146

Obtaining and Photocatalytic Properties of Ni-Doped Nanotubular Titanium Oxide

Photocatalytic properties of Ni-doped nanotubular titanium oxide(Ni-NTO) obtained by anodizing at 30 V anodizing voltage and duration about 40 minutes was studied. Nickel doping of NTO was carried out by immersion in a solution of 0.1 M nickel nitrate for various times, followed by annealing in air.The authors appreciate the support of this work within the government assignment № AAAA-A19-119110190048-7

Validation and Calibration of Models for Reaction-Diffusion Systems

Space and time scales are not independent in diffusion. In fact, numerical simulations show that different patterns are obtained when space and time steps ($\Delta x$ and $\Delta t$) are varied independently. On the other hand, anisotropy effects due to the symmetries of the discretization lattice prevent the quantitative calibration of models. We introduce a new class of explicit difference methods for numerical integration of diffusion and reaction-diffusion equations, where the dependence on space and time scales occurs naturally. Numerical solutions approach the exact solution of the continuous diffusion equation for finite $\Delta x$ and $\Delta t$, if the parameter $\gamma_N=D \Delta t/(\Delta x)^2$ assumes a fixed constant value, where $N$ is an odd positive integer parametrizing the alghorithm. The error between the solutions of the discrete and the continuous equations goes to zero as $(\Delta x)^{2(N+2)}$ and the values of $\gamma_N$ are dimension independent. With these new integration methods, anisotropy effects resulting from the finite differences are minimized, defining a standard for validation and calibration of numerical solutions of diffusion and reaction-diffusion equations. Comparison between numerical and analytical solutions of reaction-diffusion equations give global discretization errors of the order of $10^{-6}$ in the sup norm. Circular patterns of travelling waves have a maximum relative random deviation from the spherical symmetry of the order of 0.2%, and the standard deviation of the fluctuations around the mean circular wave front is of the order of $10^{-3}$.Comment: 33 pages, 8 figures, to appear in Int. J. Bifurcation and Chao

Cobalt Doped Nanotubular Titanium Oxide

This paper presents a study Co-doped nanotubular titanium oxide (Co-NTO) obtained by anodizing at 30 V 40 min. Cobalt doping of NTO was carried out by immersion in a solution of 0.1 M cobalt nitrate for various times, followed by annealing in air.The authors appreciate the support of this work within the government assignment № AAAA-A19-119110190048-7

The memristive artificial neuron high level architecture for biologically inspired robotic systems

© 2017 IEEE. In this paper we propose a new hardware architecture for the implementation of an artificial neuron based on organic memristive elements and operational amplifiers. This architecture is proposed as a possible solution for the integration and deployment of the cluster based bio- realistic simulation of a mammalian brain into a robotic system. Originally, this simulation has been developed through a neuro-biologically inspired cognitive architecture (NeuCogAr) re-implementing basic emotional states or affects in a computational system. This way, the dopamine, serotonin and noradrenaline pathways developed in NeuCogAr are synthesized through hardware memristors suitable for the implementation of basic emotional states or affects on a biologically inspired robotic system

A novel method of silicon synthesis by CVD

Silicon fibers were synthesized by a novel CVD method including in the interaction of aluminum monofluoride with silicon oxide, the final product containing nanofibers in an amount of 15 wt. %. The possibility of selective reduction of silicon oxide from the chamotte refractory plate was also demonstrated. Si was characterized by SEM and XRD. Thermodynamics and mechanism of silicon fiber formation were also considered. © 2019 Author(s)

Novel method of silicon synthesis by CVD

Silicon fibers were synthesized by a novel CVD method including in the interaction of aluminum monofluoride with silicon oxide, the final product containing nanofibers in an amount of 15 wt. %. The possibility of selective reduction of silicon oxide from the chamotte refractory plate was also demonstrated. Si was characterized by SEM and XRD. Thermodynamics and mechanism of silicon fiber formation were also considered. © 2019 Author(s)