Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)

Радиофизика, электроника, акустика

Modeling battery systems – problems of nonlinearity, efficiency, aging, coupling, and network setup

We discuss several problems of batteries and fuel cells from the point of view of nonlinear dynamics and review some earlier work on modeling this class of systems as well as new developments. We consider batteries and fuel cells as active nonlinear electrochemical circuits with properties depending on many factors as load, age, load history etc. We show that most satisfactory battery regimes are reached by coupling of an odd number of circuits in opposite phases.

Tamm resonances control in one-dimensional microwave photonic crystal for measuring parameters of heavily doped semiconductor layers

The possibility has been explored to control the photonic Tamm resonances (TRs) in the one-dimensional microwave photonic crystal (MPC) with the dielectric filling by changing the thickness of the MPC’s outer layer adjacent to the heavily doped layer of the semiconductor GaAs structure. The controlled photonic TRs have been used to measure the conductivity of the heavily doped semiconductor layer.

Decrease of low-frequency spectral power in a heart rate variability signal in a mathematical model of the cardiovascular system of arterial hypertension patients

Background and Objectives: Index equal to the spectral power of the low-frequency oscillations from the time series of the time intervals between the hearts contractions are often used when investigating the cardiovascular system. Experimental studies have shown that this spectral index was a preclinical marker of cardiovascular diseases, including arterial hypertension and diabetes.

Electrical properties of a composition based on polydimethylsiloxane filled with gallium oxide

In the present paper, the effect of gallium β-oxide introduced into the polydimethylsiloxane elastomer on the electrical properties of the composite material is investigated. The dependence of the electrical resistance of the composition on the change in the specific volume electrical conductivity on the content of gallium oxide is established experimentally and the percolation point is determined. The percolation point is 21%, which is slightly higher than the theoretical value calculated by the Monte Carlo method and is 16%.

Oscillation modes of a linear oscillator, induced by frequency fluctuations in the form of non-Markovian dichotomous noise

Background and Objectives: A set of differential equations is derived for the probability density functions of the phase coordinates of dynamic systems featuring parametric fluctuations in the form of non-Markovian dichotomous noise having arbitrary distribution functions for life at the states ± 1. As an example, the first moment of the phase coordinate of an oscillator was calculated, its perturbed motion being described by a stochastic analogue of the Mathieu–Hill equation.