Радиофизика, электроника, акустика

Background and Objectives: Microwave Bragg structures are used to create various types of microwave devices, including tunable resonators, directional couplers, miniature antennas, matched loads, various types of microwave filters with controlled characteristics. Coaxial Bragg structures based on coaxial elements, which are one of the most common types of microwave elements in waveguide systems, are characterized by a wide frequency range and the absence of radiation losses.

Backgrounds and Objectives: Networks of coupled dynamical o scillators are of high interest for last decades. The interest to their dynamics greatly increases with the discovery of chimera states. The latter are characterized by the coexistence of regions with coherent and incoherent behavior. There are many works devoted to the networks with nonlocal coupling topology, but the influence of the coupling topology type has not been sufficiently studied.

Background and Objectives: The object of our study is a network of identical bistable time-delayed feedback systems coupled via the mean field and driven by an external harmonic signal. The mean field that provides the global coupling of time-delay systems has its own delay time, which allows one to take into account the final speed of signal propagation and processing in the medium through which the oscillators are connected.

Background and Objectives: Recently, special attention in nonlinear dynamics and related research fields was targeted to the study of chimera states in networks of coupled oscillators. Chimeras were revealed in ensembles of nonlocally coupled identical systems which are described by both discrete- and continuous-time chaotic systems.

High sensitivity of an electromagnetic wave transmission spectra to change the thickness of the nanometer metal layers on dielectric plates in the case of the waveguide-dielectric resonance emergence due to the waveguide cross section is partially filled across the width and asymmetrically occupied relative to its middle by the investigated structure has been established.

Background and Objectives: Systems with hyperbolic chaos should be of preferable interest due to structural stability (roughness) that implies insensitivity to variation of parameters, manufacturing imperfections, interferences, etc. However, until recently, exclusively formal mathematical examples of this kind of dynamical behavior were known. It makes sense to turn to purposeful constructing the systems with hyperbolic dynamics appealing to tools of physics and electronics.

Background and Objectives: One of the fundamental features of the temporal dynamics is Poincare recurrence. It have been shown that statistics of return time in global approach depends on topological entropy h. The case of h > 0 (set with mixing) has been already studied theoretically. The theoretical conclusions have been confirmed by numerical simulation. The case of the sets without mixing (h = 0) has been studied theoretically, but recent numerical results shows some special aspects which are absent in theory.

Background, Objectives and Methods: The problem of diffraction of acoustic waves on the lattices located in the layered media is of great scientific interest in hydroacoustics. There are many methods of the solution of this diffraction problem, such as the method of the surface integral equations, finite element method, boundary element method, etc. One of universal method of solution of diffraction problems is the modified method of discrete sources (MMDS).

Background and Objectives: The object of our study is a system for secure information transmission based on time-delay generators. The choice of the model is justified by the fact that time-delay systems can be easily realized in experiment and they can exhibit chaotic behavior with a large number of positive Lyapunov exponents (hyperchaos). A transmitter uses the modulation of the delay time of a chaotic generator by a binary information signal.

Background and Objectives: Researches in the field of electronic circuit development for microwave informational systems based on magnetization oscillations and waves have been performing since the 1960s of the last century. The surge of interest in spin waves (SW) during the last decade is caused by the perspective to use SW as information carriers on the sub-micromagnetic and nanometer scale that leads to the fabrication of devices on magnonic principles and a significant miniaturization of spin-wave devices.