Using the nonequilibrium Green’s function method, we theoretically study the Andreev reflection(AR) in a four-terminal Aharonov-Bohm interferometer containing a coupled double quantum dot with the Rashba spin-orbit interaction (RSOI) and the coherent indirect coupling via two ferromagnetic leads. When two ferromagnetic electrodes are in the parallel configuration, the spin-up conductance is equal to the spin-down conductance due to the absence of the RSOI. However, for the antiparallel alignment, the spin-polarized AR occurs resulting from the crossed AR (CAR) and the RSOI. The effects of the coherent indirect coupling, RSOI, and magnetic flux on the Andreev-reflected tunneling magnetoresistance are analyzed at length. The spin-related current is calculated, and a distinct swap effect emerges. Furthermore, the pure spin current can be generated due to the CAR when two ferromagnets become two half metals. It is found that the strong RSOI and the large indirect coupling are in favor of the CAR and the production of the strong spin current. The properties of the spin-related current are tunable in terms of the external parameters. Our results offer new ways to manipulate the spin-dependent transport.
As the key unit in coal preparation and utilization, equal-thickness screens characterized by a large capacity and high efficiency have been extensively applied in coal preparation plants. Recently, the noise pollution caused by the screening of coal has become more and more serious.
Reducing the noise of vibrating screens is the key to control the noise of coal preparation plants. In this article, the noise test system was used to measure three-dimensional (3D) sound intensity of the equal-thickness screen. According to the analysis of sound intensity distribution and
spectral coherence, the main sources of noise were identified. The main sources of noise of equal-thickness screen were vibration motors, side panel, screen surface and damping supports. A displacement model was fitted to the experimental data, and the kinematics of the sieve body was studied.
The results showed that the amplitude of the sieve body decreased as the distance from the feeding end (towards the discharge end). Similarly, the intensity of the noise decreased about 2 dB in the same direction (from the feeding end to discharge end). However, in the direction perpendicular
to the movement of the material, the noise distribution was symmetrical. Finally, various noise reduction measures were also put forth. It could be seen that when the composite spring was adopted as the damping support and the structures of vibration motors, screen surface and side panel were
changed, the noise could be effectively reduced.
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