Multistable and chaotic self-oscillations in ring DT–oscillators
Multistable and chaotic self-oscillations in ring DT–oscillators
V.V. Zaitseva , E.N. Krygina, S.V. Lindt
The results of numerical simulation of self-oscillations in a two-stage ring oscillator with active cells of Van der Pol are presented. It is shown that for large excesses of generation threshold in a system with identical cells, non-uniform spatial distribution of amplitudes of self-oscillations is observed. Regular and chaotic self-oscillations in ring DT- oscillators are investigated.
Show AbstractAnalysis of coherent structures in helical electron beam in the regime of the squeezed state
Analysis of coherent structures in helical electron beam in the regime of the squeezed state
E.N. Egorov$^{1}$, V.V. Makarov$^{1,2}$, A.E. Hramov$^{1,2}$
The results of numerical simulations and analysis of non-stationary dynamics of helical electron beam in the vircator with magnetron injection gun with additional braking field are presented. We have revealed the fields of the control parameters where the squeezed state is realized in such system. Peculiarities of the dynamics of the beam in squeezed state are analyzed. By means of Karhunen–Louve decomposition the processes of appearance and propagation in the beam in squeezed state of the space-charge wave are analyzed.
Show AbstractSpectroscopic studies of samarium chromium borate SmCr$_3$(BO$_{3}$)$_4$
Spectroscopic studies of samarium chromium borate SmCr$_3$(BO$_{3}$)$_4$
E.A. Dobretsova, K.N. Boldyrev
The optical spectra, thermal and magnetic properties of the compound SmCr$_3$(BO$_3$)$_4$ were investigated in a wide temperature range. A series of phase transitions at temperatures of T$_1$ =8,0 ± 0,5К, T$_2$=6,7 ±0,5К and T$_3$=4,3 ± 0,2К. were found. First two transitions at the temperatures T1 and T2 are second order phase transitions and, most likely, correspond to antiferromagnetic ordering of subsystem Cr$^{3+}$ and, then, crystal transition to the ferroelectric state. First-order phase transition at a temperature of 4,2 ± 0,2K most likely corresponds to the spin-reorientation of the chromium magnetic moments.
Show AbstractSpin-injection stimulated radiation of Terahertz Waves in magnetic Junctions
Spin-injection stimulated radiation of Terahertz Waves in magnetic Junctions
A.V. Chernych$^{2}$, S.G. Chigarev$^{1}$, Yu.V. Gulyaev$^{1}$, G.M. Mikhailov$^{2}$, E.A. Vilkov$^{1}$, P.E. Zilberman$^{1}$
The mechanism of stimulated terahertz radiation was investigated for spin–injection oscillators. The feedback performs due to semitransparent mirror arranged on the back surface of the substrate. The influence of the feedback on spectral characteristics and radiation intensities of the oscillator are discussed.
Show AbstractTime-frequency analysis of patterns in activity of brain neuron ensemble by means of wavelet transform
Time-frequency analysis of patterns in activity of brain neuron ensemble by means of wavelet transform
V.V. Grubov$^{1,2}$, A.A. Koronovskii$^{1,3}$, E.Yu. Sitnikova$^{4}$, A.E. Hramov$^{1,2}$
In present work time-frequency characteristics of sleep spindles on EEG of WAG/Rij rats were studied by means of continuous wavelet transform. General frequency structure and average length was revealed, also complex dynamics during sleep spindle was discovered and tendency to growth of frequency from beginning to end of sleep spindle was shown. Structure changes in sleep spindles caused by aging of rats and evolving of epilepsy were discovered. Dynamics of sleep spindles appearing on EEG was studied and it was shown that it could be described by means of on-off intermittency theory.
Show AbstractDensity plasma excitations of two-dimensional semiconductor superlattice in a wide range of parameters
Density plasma excitations of two-dimensional semiconductor superlattice in a wide range of parameters
S.Yu. Glazov$^1$, I.S. Gromyshov$^1$, N.E. Mescheryakova$^2$
Investigated plasma density excitations in two-dimensional semiconductor superlattice depending on the period and the width of the potential wells, forming a superlattice. Calculations were performed on base of the quantum theory plasma oscillations in random phase approximation taking into account the umklapp processes. Estimation of parameters of superlattice was performed using the Kronig–Penney model.
Show AbstractS–polarized spectrum of one-dimensional photonic crystal with anisotropic nanocomposite defect layer
S–polarized spectrum of one-dimensional photonic crystal with anisotropic nanocomposite defect layer
S.Ya. Vetrov$^{1,2}$, P.S. Pankin$^2$, I.V. Timofeev$^{1,2}$
Spectral properties are investigated of one-dimensional photonic crystal with structure defect which is considered as an anisotropic nanocomposite layer embedded between two multilayer dielectric mirrors. A number of important features in the transmission spectrum of the photonic crystal are found.
Show AbstractNonlinear waves in microtubules of nerve cells
Nonlinear waves in microtubules of nerve cells
A. N. Bugay$^1$, S. Zdravkovi´c$^2$
Microtubules are important cytoskeleton element of living organisms. In this research nonlinear waves in microtubules are studied, and different types of soliton solutions are derived. Soliton solutions describe propagation of polarization and deformation waves within localized structural transition in microtubule.
Show AbstractEdge modes of two dimensional bounded photonic crystal structures composed of small plasmonic particles and their interaction with inner structure's waves
Edge modes of two dimensional bounded photonic crystal structures composed of small plasmonic particles and their interaction with inner structure's waves
Yu.N. Barabanenkov$^{1}$, M.Yu. Barabanenkov$^{2}$
Specific optical eigenmodes are considered of finite clusters of metallic nanoparticles with plasmonic resonance as well as an excitation transfer along linear chain of particles between clusters. Simple analytic and physically transparent results are presented for the problem solution of collective modes exciting inside two dimensional circular clusters and the problem excitation transfer along one dimensional linear array of coupled small plasmonic spherical particles. The results are obtained with the aid of equations’ system for self-consistent currents excited inside particles by incident electromagnetic wave field. For circular cluster of particles the coupling matrix between their currents becomes under definite conditions of such favorite properties that enables one immediately to write out the Bloch–like eigenmodes with corresponding eigenfrequencies and their half widths. What is more we get also a simple analytic expressions for coupling factor between inner part of a square structure arranged in a circular shape and its bound part. Considering linear array of particles we use a closest neighbor interaction approach which makes the linear array like the electric filter. In this approximation an analytic expression are obtained for extinction rate of exciting currents’ transfer depending on array particles number and for resonance filtering frequencies.
Show AbstractAnalysis of electrodynamic characteristics of a spiral microwave rectenna
Analysis of electrodynamic characteristics of a spiral microwave rectenna
K.T.C. Vu, R.V. Egorov, V.L. Savvin, D.A. Mikheev
The study treats properties of a microwave rectenna, consisting of a semiconductor diode and a spiral antenna, that has a resonant frequency of 10 GHz. The radiation pattern of the rectenna was demonstrated to be omnidirectional within a wide range of elevation angles.
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