Volume 83, Nº 1 (2019)

A version of a molecular nanotransistor with improved efficiency and reliable isolation of side gates is developed and tested. The correlated nature of electronic transport in the transistor and high resistance of the isolation of the gates (more than 1 TΩ) ensure the correct mode of measuring the transistor control characteristics.

The dependence of the current density in graphene, the energy spectrum of which contains a forbidden band, on the characteristics and orientation of applied static and alternating electric fields is investigated. Graphene’s electronic system is described using the Boltzmann kinetic equation in the constant relaxation time approximation. The effect of changing the direction of direct current at certain values of the intensity of a transverse static field and the amplitude of oscillations of an alternating transverse electric field is examined.

The formation of optical bullets in propagating light beam pulses inside a planar waveguide with quadratic nonlinearity is studied. Cases of a waveguide with saturation and an unlimited waveguide with a quadratic profile of the change in the refractive index are considered.

Three nondegenerate processes are considered: the parametric and simultaneous generation of sum frequencies in a periodically poled nonlinear crystal. The behavior of the average number of photons of interacting modes and their mutual correlations of orders 3, 4, and 5 are studied numerically. A new effect of inversion of the mutual correlation of the modes of the generated radiation is observed at certain length of interaction.

Studying the conversion of terahertz radiation into electric current is of great interest for finding new ways of using the energies of solar and thermal radiation, designing new IR detectors, and other purposes. The processes that occur during the rectification of terahertz signals can be considered within the theory of tunneling stimulated by photons.

A numerical analysis is performed of the interaction between a relativistic electron beam and the field of a rectangular resonator excited in the ТЕ₁₀₁ mode. It is shown that this interaction can be accompanied by considerable disturbance of the resonant conditions, due to a change in the cyclotron frequency and the sharp deceleration of the beam, caused by the effect of the magnetic component of the HF field in the resonator.

A technology is developed that uses two multiscale structures on a single crystal piezoelectric substrate of lithium niobate. A system of counter-pin electrodes for an acoustic delay line operating in the 2–3 MHz range is formed via photolithography. The system is combined with nanotransducers 60–80 nm in size, produced by means of negative electron-beam nanolithography.

A procedure is described for reconstructing separately the spatial distributions of the absorption coefficient, speed of sound, and the intrinsic temperature of an investigated object by means of acoustic thermotomography. The use of radiation focusing in combination with additional anisotropic backlighting is required. Objects with arbitrary shape, small wave sizes, and arbitrary sizes are considered.

The basic principles of the reverse wave approach are presented. A new algorithm for processing experimental data is developed. Several test models of an inhomogeneous three-dimensional medium are proposed. The new algorithm is tested with synthetic input data determined in the ray approximation for test models. The results from determining the structure of the Earth’s crust are presented using the Azerbaijan region as an example.

The phenomenon of acoustic radiation force acting on solid spherical scatterers inside the field of a focused ultrasonic beam is experimentally studied. Nylon and glass beads are used as scatterers; the acoustic field is generated by a piezoceramic transducer of the megahertz frequency range in water. The angular spectrum of the ultrasonic beam, obtained from the measured transverse distribution of the amplitude and phase of the acoustic pressure, is used to calculate the theoretical value of the radiation force. The results from these calculations are in agreement with the experimentally determined value of the radiation force.

Protein folding is considered as an autowave self-organization process in active media, where the homochirality of primary structures creates a distributed store of energy. A quantitative model description is presented for the already established folding pattern of stratified structure formation with a variable chirality sign in the hierarchies of L-amino acids, D-α-helices, and L-super-helices.

Many well-known types of tornado (e.g., atmospheric (air), electric, fire, dust, liquid (water), and snow) are classified according to their substrates and shapes. Known tornado theories are also given. In this work, a model of a tornado is proposed in which it is a structure that arises in the active medium of a thundercloud, where concave spiral autowaves that transfer energy excite vortices that travel into the environment. An exact analytical solution is given to the vortex regimes of the Navier—Stokes equation for a tornado model. The results from computer modeling of rotational concave spiral autowaves that excite a tornado vortex are given. The satisfactory nature of the proposed model with regard to the set of basic properties of a tornado and the variety of its characteristic properties is shown.