Herein, we report the first example showing the reversible on-off switching of spin-crossover (SCO) property by solid state photochemical [2+2] reaction. The ultraviolet (UV) light-induced [2+2] cycloaddition reaction of 3-spy ligands in a twodimensional (2D) Hofmann-type framework [Fe(3-spy) 2 {Pd(CN) 4 }] (1, 3-spy=3-styrylpyridine), which shows a hysteretic twostep SCO behavior, gives a 3D Hofmann-type framework [Fe(rctt-3-ppcb){Pd(CN) 4 }] (2, rctt-3-ppcb=rctt-1,3-bis(3-pyridyl)-2,4-bis(phenyl)cyclobutane, r=reference group, c=cis and t=trans) accompanied with the disappearing of SCO properties. Moreover, upon heating at 250 °C for 12 h, the rctt-3-ppcb ligand in 2 could be partially dedimerized to 3-spy with 68% completion through single-crystal-to-single-crystal (SCSC) transformation, giving the annealing complexes [Fe(3-spy) 1.36 (rctt-3-ppcb) 0.32 {Pd(CN) 4 }] (3) which display an incomplete SCO behavior. The 2 ⇌ 3 interconversion is successfully achieved via continuous UV irradiation and thermal annealing, demonstrating the effectiveness of photochemical [2+2] reaction on switching on-off SCO properties.

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This study is primary to develop relevant techniques for the bearing of wind turbine, such as the intelligent monitoring system, the performance assessment, future trend prediction and possible fault classification etc. The main technique of system monitoring and diagnosis is divided into three algorithms, such as the performance assessment, performance prediction and fault diagnosis, respectively. Among them, the Logistic Regression (LR) is adopted to assess the bearing performance condition, the Autoregressive Moving Average (ARMA) is adopted to predict the future variation trend of bearing, and the Support Vector Machine (SVM) is adopted to classify and diagnose the possible fault of bearing. Through testing, this intelligent monitoring system can achieve real-time vibration monitoring, current performance assessment, future performance trend prediction and possible fault classification for the bearing of wind turbine. The monitor and analysis data and knowledge not only can be used as the basis of predictive maintenance, but also can be stored in the database for follow-up off-line analysis and used as the reference for improvement of operation parameter and wind turbine system design.

A novel design of a vibration absorber used in reducing the torsional vibration of a crankshaft is proposed. When a crankshaft is rotating, its natural frequency corresponding to the first torsional mode varies due to the inertia force. The proposed vibration absorber is installed inside the cavity of the front pulley and rotates with the crankshaft. Therefore its natural frequency also varies with the rotating speed. The objective is to design a vibration absorber whose torsional natural frequency not only varies with the rotating speed but also coincides with the varying natural frequency of the rotating crankshaft. Thus it can effectively suppress the torsional vibration of the crankshaft when a vehicle cruises at a varying speed. Results from numerical simulations using the finite element method show that the torsional vibration of the crankshaft can be reduced by more than 45 dB.