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In recent years, social networking platforms such as Sina Weibo and Twitter have gradually become one of the main carriers for reflecting social public opinion, providing a convenient platform for netizens to express their opinions and emotions.Public opinion monitoring based on social network big data has become a new research hotspot.People’s emotions monitoring using social network big data in various countries is helpful to directly grasp people’s emotional tendencies in international relations, and has a great impact on the diplomacy, foreign trade, and other aspects.Based on this, a public sentiment monitoring system for Chinese and Japanese data was proposed, which could analyze the emotional tendencies contained in Chinese and Japanese data on social platforms such as Sina Weibo and Twitter simultaneously, and displayed them to users in a visual form.In the aspect of sentiment analysis algorithm, based on the BERT model and combined with the self-expanding Chinese and Japanese sentiment lexicon, a new sentiment analysis model, EmoBERT, was proposed.The experimental results show that, compared with the original BERT model, the EmoBERT has achieved good results on both Chinese sentiment classification tasks and Japanese sentiment classification tasks.Among them, EmoBERT-C increases the accuracy of Chinese BERT from 89.68% to 92.15%, and EmoBERT-J increases the accuracy of Japanese BERT model from 74.73% to 78.26%.

The ANSI/AGMA 2003-B97 is a widely used bending stress checking standard for spiral bevel gears. The calculation formula of bending strength checking is carried out， the key parameters are modified， the problem of insufficient safety margin of bending strength checking solved， and this method is verified by finite element contact analysis. Based on the modified bending strength checking standard， the strength checking software of spiral bevel gear is developed， and the optimal design scheme of tooth surface is given. The proposed method can improve the accuracy and efficiency of tooth surface bending strength checking calculation.

In order to improve the structural performance of the aero-engine gearbox housing and reduce the adverse effects of the engine bad working conditions on the supporting components， the topology optimization theory based on variable density method is adopted， and the minimum flexibility index and weighted average transverse eigenvalue are taken as the target number， and the coupling of thermal-elastohydrodynamic-lubrication effects of the supporting components are considered. Taking the maximum deformation less than 0.15 mm and the equivalent stress less than the material stress as the constraint conditions， the topology optimization design of the aero-engine gearbox housing is carried out. According to the topology optimization results， the geometric reconstruction of the housing structure is carried out， and the strength， stiffness and mass of the shell structure before and after optimization are compared and analyzed. The results show that， after optimization， the housing mass is reduced from 5.53 kg to 5.107 kg， the weight is reduced by 7.6%， the maximum deflection of the housing is reduced from 0.173 1 mm to 0.127 mm， the deformation is reduced by 26.6%， the maximum equivalent stress of the housing is reduced from 124 MPa to 116.9 MPa， the stress is reduced by 5.7%.The maximum deformation and equivalent stress of the housing are effectively reduced， and the strength and stiffness of the housing are significantly improved. It is of great significance to improve the reliability and service life of aero-engine central transmission shell.