Oleg Viktorovich Karpov

Modeling of rf-biased overdamped Josephson junctions

This paper presents a mathematical model for determining the stable phase-lock areas of microwave-biased superconductor-normal metal- superconductor Josephson junctions with low normal state resistance and small junction capacitance. The calculations are based on the resistively shunted junction model. The theoretically determined phase-lock areas are in accordance with the experimental results on Nb/HfTi/Nb junctions.

THEORETICAL RESEARCH OF THE SCAFFOLDER AND SOIL INTERACTION

The purpose of research is to improve the dosing of mineral fertilizers sowing unit, depending on the physico-mechanical properties of the soil. In modern technologies of precision farming with differentiated application of mineral fertilizers, data from various sensors, results of analyzes of soil samples and aerial photography are mainly used, without taking into account factor such as the depth of the humus horizon, which largely determines the soil fertility. On the basis of the Samara State Agricultural Academy, studies are underway on the effect of the depth of the humus horizon on the fertility of the soil. Several machines have been developed for differentiating mineral fertilizers with spreader and cultivator. Currently, a system of differentiated application of mineral fertilizers is being developed for sowing agricultural crops and it is planned to produce a set of equipment for a standard seeder UCS-8 Vesta. A constructive scheme of the device for determining the traction resistance is presented, which is closely related to the depth of occurrence of the humus layer. The main working element of this device is a deformer in the form of a knife, with a dihedral grinding. The article presents theoretical studies of the effect of forces acting on a deformer. Based on the results of the theoretical justification of the technological process of the proposed scheme for determining the traction resistance, the load dependencies on the strain gauge link were derived depending on the drag resistance of the deformer, which is determined by its basic design and technological parameters and the physical and mechanical properties of the soil. The obtained dependences of the traction resistance of the working organs of the tillage implement will theoretically determine the additional energy costs from the introduction of the deformer in the design stage at the design stage of the machine and outline the directions for their optimization.

A quantum digital ac-voltage synthesizer based on pulse-width modulation of the Josephson junction bias current

The theory and preliminary results of the experimental tests of a method for synthesizing ac-voltage signals through the use of pulse-width modulation of the microwave power biasing a Josephson junction are presented. It is shown that it is possible to synthesize sinusoidal ac-voltage signals with an amplitude of 1 V and a nonlinear distortion factor of <0.003%.