Stationary Charge Imbalance Effect in System of Coupled Josephson Junction

We investigate stationary charge imbalance effect in the system of coupled overdamped Josephson junctions. We show that coupling between junction and nonzero stationary charge imbalance in the resistive state bring to a decrease of the Josephson frequency in the Josephson junctions of the stack. The formed difference in Josephson frequency leads to the nonuniform switch to the Shapiro step regime in the presence of external electromagnetic radiation and appearance of kinks of voltage on the IV-characteristics of the stack. We also show that stationary charge imbalance brings to the slope of the Shapiro step due to the difference of the charge imbalance potential on the edges of the step. The theoretical and experimental results for voltage bias coupled Josephson junctions have been compared with the current bias case

Improvement of the homogeneity of magnetic field by the attenuation of a selected component with an open superconducting shield made of commercial tapes

Homogeneous magnetic fields are needed in many applications. The resolution of medical imaging techniques depends on the quality of the magnetic field, as does the efficiency of electron cooling systems used at particle accelerators. Current methods of improving homogeneity require complex arrangements of magnet windings. In this work, the application of commercial superconducting tapes for this purpose is analyzed experimentally and numerically. The shielding effect exhibited by the superconductors can be used to control the shape of the magnetic field. An open magnetic shield made of superconducting tapes is able to nullify the radial component of a solenoidal magnetic field, forming the long region of the homogeneous magnetic field. To form a shield, the superconducting tapes are wound on a former. Then, it is positioned coaxially inside an electromagnet. The measurements are performed in the DC magnetic field and at zero-field cooling conditions. A numerical model is developed to further analyze the magnetic field. New simplifications and proper constraints allow the use of an axial symmetry despite relatively complex geometry of the shields. Results from the simplified model and obtained experimentally are consistent. The decrease of radial component of the magnetic field and the significant improvement of its homogeneity are observed in a shielded region. The decrease of shielding quality with the increase of an applied magnetic field is observed. Empirical formulas describing the dependence of shielding quality on the geometry and the critical current of the shield are developed

Development of crowding-in as an alternative form of small and mediumsized businesses financing: foreign experience and Russian practice

The article presents a comprehensive analysis of legal and economic measures aimed at state support for small and medium-sized businesses in order for them to obtain an alternative source of financing using crowdinvesting platforms, and a consimilar foreign experience research. Based on statistical data, conclusions on the crowdinvesting platforms sector’s development and its interaction with small and medium-sized businesses are presented. Within the frameworks of the article, the emphasis is placed on a detailed study of foreign experience in the providing an alternative funding source. The advantages and disadvantages of this method in the Russian context have been shown. The study involved an analysis and synthesis of domestic and foreign anti-crisis measures

Shell forming mode effect on casting quality

The paper deals with the influence of shell forming modes on some parameters of castings: the surface and internal defects. The degree of roughness and stress concentration were determined on the castings obtained under production conditions. According to the result, it was found that the use of variable pressure in the formation of the shell ensures the purity of the casting and the reduction of the stress level in the casting

Chromium-nickel cast iron composition effect on properties and graphitization process

The paper considers the cast iron based on nihard-2 composition effect on the properties and process of graphitization. It is shown that changing the Cr:Si ratio equal to 2:1 leads to the development of the graphitization process, as a result of which lamellar graphite appears in the structure. Subsequent modification leads to changing the shape of the graphite into the nodular one, which leads to some decrease in hardness but increases resistance to abrasive wear by about 20-25 %