-

Memory notes about childhood at the time of the Great Patriotic war.

Investigation and development of e?cient electromagnetic oscillations sources are one of the topical issues in the ?eld of terahertz radiophysics and electronics. A frequency region is regarded as an explored for which oscillating, amplifying and measurement devices have not been developed. The exploration of the terahertz frequency range is at the initial state.

The role of the discrete description of electron-wave interaction in high-power traveling wave tubes is shown. Deals with the development of this trend on the basis of the theory of interaction of the di?erence equation excitation waveguides. The validity of the linear theory and developed a universal characteristic equation of electron waves, using the di?erence equation excitation waveguides in stopbands of slow-wave systems.

Authors used the simple mathematical models as a base for the discussion of the evolution of  human society.

We review the results of studies of spontaneous and stimulated emission of relativistic particles in natural and photonic crystals.We consider the di?raction of electromagnetic waves in a crystal, and the resonance and parametric (quasi-Cherenkov) X-ray radiation, the radiation in the channeling of relativistic particles in crystals, di?raction radiation in conditions of channeling, di?raction radiation of a relativistic oscillator, induced radiation in multidimensional space-periodic resonators (natural or arti?cial (electromagnetic, photonic) crystals).

Experimental and theoretical study of nonlinear dynamics and acoustic signals generated by periodic impacts of corundum probe on the solid surface are conducted. In the work two models are considered for the description of experiments: the analytical model based on the laws of conservation of energy and momentum; the model based on the numerical solution of the nonlinear equation of probe motion. It is shown that the acoustic signal amplitude increases in direct proportion to the oscillations probe amplitude.

The work presents the results of experimental investigation of roller domains parametrically excited by the capillary waves. Domains rollers were oriented parallel to the di?erent borders of the rectangular cell and perpendicular to each other. Found that depending on the initial and boundary conditions on the edges of the cell can emerge two-dimensional domains of di?erent forms. The dynamics of the domain is determined by the movement of their fronts. A model is proposed to explain the observed phenomena, numerical calculations by which agree well with experiment.

We propose a full solution for Manna model – two-dimensional conservative sandpile model with the rules of grains redistribution isotropic at the average. Indices of the probability distributions of avalanches main characteristics (size, area, perimeter, duration, topplings multiplicity) are determined for this model both from theory and from simulations.  The solution bases on the spatiotemporal decomposition of avalanches described in terms of toppling layers and waves.

The problem of the excitation of two coupled oscillators is discussed in the case of the simple subharmonic resonance between the external force and eigen-frequencies of the oscillators. The corresponded phase equation is obtained.

Sergei P. Kurdyumov (1928–2004) and his distinguished contribution in the development of the modern interdisciplinary theory and methodology of study of complex self-organizing systems, i.e. synergetics, is under consideration in the article. The matter of a mathematical model of evolutionary dynamics of complex systems elaborated by him is demonstrated. The nonlinear equation of heat conductivity serves as a basis of the model.