scholarly journals Физические принципы создания магнитолевитационных систем на основе высокотемпературных сверхпроводящих композитов второго поколения (Обзор)

2021 ◽  
Vol 91 (12) ◽  
pp. 1813
Author(s):  
И.А. Руднев ◽  
И.В. Анищенко
Keyword(s):  
High Temperature Superconductors ◽  
Thermal Processes ◽  
Theoretical Studies ◽  
Bulk Superconductors ◽  
Htsc Tape ◽  
Materials Used ◽  
Alternating Magnetic Fields ◽  
Experimental And Theoretical Studies ◽  
Htsc Composites ◽  
Force Characteristics

An overview of experimental and theoretical studies of the characteristics of maglev systems using high-temperature superconductors (HTSC) is presented. Materials used in maglev technologies, namely bulk superconductors and HTSC tape composites, are considered. The main experimental data obtained on both bulk and tape superconductors assembled in stacks of various configurations are demonstrated. The factors influencing the magneto-force characteristics are analyzed: geometric parameters, the influence of external alternating magnetic fields, temperatures, relaxation phenomena. A significant part of the review is devoted to the description of various methods for calculating maglev systems, including those based on stacks of HTSC composites. The features of thermal processes in maglev systems with cryocooler and nitrogen cooling are considered. General recommendations for the creation of optimal maglev systems based on tape HTSC composites are given.

scholarly journals Temperature modes of the contactor contacts during the test for the limiting breaking capacity

2020 ◽  
Vol 220 ◽  
pp. 01065
Author(s):  
E.G. Egorov ◽  
A.G Kulagina ◽  
N.Yu. Luiya ◽  
R.V. Fedorov ◽  
V.N. Pichugin
Keyword(s):  
Mathematical Models ◽  
Thermionic Emission ◽  
Heat Fluxes ◽  
Thermal Processes ◽  
Theoretical Studies ◽  
Ionic Component ◽  
Electrical Devices ◽  
Calculation Results ◽  
Temperature Equalization ◽  
Experimental And Theoretical Studies

The processes of electric arc quenching of an electromagnetic contactor during testing for ultimate breaking capacity are considered. The conditions for facilitating the successful arc quenching when turning off the limiting currents are shown: by reducing the phase shift between current and voltage, by reducing the amplitude of the restriking and recovery voltages. The processes of anode heating during arcing (heat saturation mode), after the change of polarity and transition of the current through zero, processes on the cathode in the temperature equalization mode are considered. The mathematical models of cathode thermal processes adressed the heat fluxes of the ionic component and evaporation. The mathematical models of anode thermal processes in the temperature equalization mode took into account the heat fluxes of the ionic component, thermionic emission, and evaporation. The calculations were carried out for the averaged values of thermophysical coefficients for copper, since the arc base moves from the contacts to the contact holders, which are made of copper or its alloys. The calculation results showed that the used mathematical models of thermal processes are appropriate both for the cathode and for the anode. This was confirmed by the results of previously performed and published experimental and theoretical studies of thermal processes at the switching contacts of electrical devices.

The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  
Keyword(s):  
High Selectivity ◽  
Side Reactions ◽  
Theoretical Studies ◽  
Attractive Feature ◽  
Catalyst Recovery ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Experimental And Theoretical Studies

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.

Strong coupling: resonant effects

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Strong Coupling ◽  
Experimental Studies ◽  
Strong Coupling Regime ◽  
Theoretical Studies ◽  
Stimulated Scattering ◽  
Quantum Theories ◽  
Pump Probe ◽  
Exciton Polaritons ◽  
Linear Optical Properties ◽  
Experimental And Theoretical Studies

This chapter presents experimental studies performed on planar semiconductor microcavities in the strong-coupling regime. The first section reviews linear experiments performed in the 1990s that evidence the linear optical properties of cavity exciton-polaritons. The chapter is then focused on experimental and theoretical studies of resonantly excited microcavity emission. We mainly describe experimental configuations in which stimulated scattering was observed due to formation of a dynamical condensate of polaritons. Pump-probe and cw experiments are described in addition. Dressing of the polariton dispersion and bistability of the polariton system due to inter-condensate interactions are discussed. The semiclassical and the quantum theories of these effects are presented and their results analysed. The potential for realization of devices is also discussed.

Homo- and heterobimetallic trihydride complexes stabilized by the tripodal phosphine ligand MeC(CH2PPh2)3: experimental and theoretical studies

1989 ◽  
Vol 28 (13) ◽  
pp. 2552-2560 ◽  
Author(s):  
Claudio Bianchini ◽  
Franco Laschi ◽  
Dante Masi ◽  
Carlo Mealli ◽  
Andrea Meli ◽  
...  
Keyword(s):  
Phosphine Ligand ◽  
Theoretical Studies ◽  
Experimental And Theoretical Studies
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