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The design optimization of a direct-drive permanent magnet synchronous generator (DDPMSG) is of great significance for wind turbines because of its unique advantages. This paper proposes a two-stage model to realize multi-objective design optimization for a 6 MW DDPMSG. In the first stage, a surrogate optimized response surface model based on an improved sparrow search algorithm (ISSA) was established for modeling the cogging torque and generator efficiency. In the second-stage model, a multi-objective optimization model is proposed to optimize the cogging torque and generator efficiency of the DDPMSG. Finally, the proposed two-stage model was used for a 6 MW DDPMSG design optimization, and the simulation results demonstrated the superiority and rationality of the proposed model. In the first-stage model, the proposed surrogate model based on the ISSA had a better modeling accuracy and lower errors. Compared with traditional response surface models and correlation analysis models, the proposed optimized surrogate model reduced errors in the cogging torque by 34.63% and 42.97%, respectively, while the errors in the efficiency models were reduced by 12.92% and 60.78%, respectively, which indicates the superiority of the first-stage model. In the second stage, compared with the single-objective optimization model, the multi-objective optimization model achieved a trade-off optimization between the cogging torque and the efficiency. Compared with the cogging torque optimization model, the proposed model optimized the efficiency by 101.41%. Compared with the efficiency optimization model, the proposed model reduced the cogging torque by 16.67%. These results verified the superiority and rationality of the second-stage model. [ABSTRACT FROM AUTHOR]

A new catalytic transfer hydrogenation (CTH) strategy was developed for the continuous conversion of furfural (FF) into furfuryl alcohol (FFA) with Cu/ZnO/Al2O3 (CZA) as the catalyst under mild conditions. Methanediol was used as the hydrogen donor without any hazardous gas emission. FF was converted into FFA with up to 99% selectivity at 108 °C and normal pressure under an N2 atmosphere. The highly dispersive copper species (Cu0, Cu+) with few Lewis acidic sites and η1(O)-type adsorption ensured high selectivity and mild conversion. Deuterium-labelling experiments revealed that, in the presence of formaldehyde, water is split into hydrogen species, which can reduce FF to form FFA. A reasonable reaction mechanism for the conversion of FF into FFA via transfer hydrogenation was proposed. Notably, this strategy offers a new route to splitting water to generate in situ "green hydrogen" for the hydrogenation of unsaturated organic compounds under mild conditions based on non-noble heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The ability of the floating offshore wind turbine foundation to withstand harsh wind and wave conditions is intrinsically linked to the meticulousness employed in the design of the mooring system. Therefore, it is vital to conduct research to reveal the variations in sensitivity of new mooring materials parameters and the response characteristics of the foundation in the presence of intricate operational circumstances. A fully coupled time-domain dynamic analysis is performed via the commercial software AQWA to examine the VolturnUS-S semi-submersible foundation, specifically engineered to support the IEA 15 MW offshore reference wind turbine. The numerical simulation results indicate that synthetic fibers, specifically Aramid and high-modulus polyethylene, can replace the steel wire as mooring materials. At the same time, the mooring arrangement, length, diameter, and fairlead position influence foundation motions and mooring tensions, bringing valuable insight into the fluctuation patterns of these responses. [ABSTRACT FROM AUTHOR]