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Active Magnetic Bearing (AMB) has been widely applied in occasions acquire high-speed rotating, high-precision machining, and so on. The AMB can provide active control force to offset centrifugal force and other disturbance to suppress vibration while rotating. This paper proposed a strategy to compensate vibration in AMB system based on Variable Step-size Automatic Learning Control (VALC). Firstly, a two degrees of freedom model of radial AMB is established. Phase error between of centrifugal force and synchronous vibration is analyzed. Then, principle and process of VALC is introduced. A generalized notch filter is applied to obtain synchronous and harmonic vibration. Next, simulations are carried out based on AMB control system applied VALC. The results of simulations show the feasibility of the compensating strategy. Experiments to reduce synchronous and harmonic vibration based on VALC are carried out on a test rig. Spectrums of vibration signals show that vibration is reduced by about 90%, which demonstrates the effectiveness of proposed strategy for vibration compensation.

Bulk heterojunction organic solar cells based on conjugated polymers and soluble fullerene derivatives have been intensively studied due to their simple device structure, easy thin-film casting process, low fabrication cost, and high power conversion efficiency. To further enhance the efficiency, it is of paramount importance to develop new p-type polymeric semiconductors with high charge mobility and narrow energy band gaps. In this paper, we report on an innovative way to synthesize low band-gap conjugated polymers with high crystallinity and reasonable solubility for wet process by using electron-acceptor cored regioregular oligothiophenes as building blocks. These novel building blocks can copolymerize with coplanar fused aromatic compounds, such as indolo[3,2-b]carbazole, to form crystalline polymers with enhanced interchain interaction. Two alternating copolymers P(InCzThnBTD) (n = 2-3) synthesized in this work show much narrower optical band gaps than widely used regioregular P3HT. In addition, the first ionization energy of both synthesized polymers remains high at ~5.17 eV, which is important to achieve large open-circuit voltage (Voc) and improve air stability. Remarkably, the bulk heterojunction photovoltaic (PV) cells fabricated from P(InCzTh2BTD) and PC61BM exhibited a promising PV performance with a PCE = 3.6 %, Voc = 0.69 V, Jsc = 9.17 mA/cm2, and FF = 0.57.