Duration of viewing was considered as one of the most important factors of 3D visual fatigue. However, their relationship was not well studied. We proposed to use brain monitoring techniques to reveal more details about the variety of brain activity while watching three‐dimensional (3D) content. We investigated the spectral patterns in the electroencephalogram related to various duration of viewing and showed the power spectral density varied significantly along with the development of fatigue over occipital lobe, parietal lobe, and right frontal lobe. Moreover, we first described the trend of brain activity during 3D content viewing and revealed the location of significant components related to 3D visual fatigue. We believe that the absolute power describes more information and may be a better indicator of 3D visual fatigue assessment compared with relative power. We also first revealed the cortex location that is related to 3D visual fatigue. Our findings may help to define appropriate electroencephalogram features for online 3D visual fatigue detection while participants viewing 3D content.

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Three-dimensional (3D) displays become more and more popular in many fields, because they can provide amazing visual effects. However, visual fatigue as one of the critical factors has seriously impeded the wide range of applications of 3D technology.

In this paper, we designed an experiment to observe changes for different fatigue level in human brain when watching random dot stereogram (RDS) using the method of EEG. The subjects were asked to watch 3D content for 30 minutes and the disparity of RDS changed every 10 seconds. During this watching task, subjects should rate their extent of fatigue during the experiment on the scale of one to five only when they felt worse or better. 30 channels electroencephalogram (EEG) signals were recorded through the experiment. Finally, the relationship between various fatigue levels and disparities which revealed by EEG signals were investigated. Our results show that the power of waveband, namely alpha increased with the fatigue level increasing from one to four during watching RDS, but decreased in level five. We have employed logistic regression to model fatigue level and achieved classification accuracy of 94.18%. Our research has important implications for the continuous monitoring of user's fatigue in the future.

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Improvements in green technology innovation efficiency is the core factor to promote to shape new advantages in resource-saving and environmental friendliness under the new pattern of double-cycle development. It is also the main driving force needed to establish a high-quality development model of an efficient and sustainable economy. Taking 30 provinces of China as case samples, this paper establishes the appraisal system of green technology innovation efficiency. The first step is using the three-stage DEA model to measure green technology innovation efficiency. Then, according to the configuration perspective, the paper uses fuzzy set qualitative comparative analysis (fsQCA) to explore multiple paths for promoting green technology innovation efficiency. The findings are as follows: (1) A single factor of environmental support or technology supply cannot effectively stimulate the improvement of green technology innovation efficiency. Therefore, the impacting factors must be matched to jointly improve green technology innovation efficiency. (2) There are three configuration paths for high green technology innovation efficiency. Namely, they are the driven by economic environment and environmental regulation type; the driven by industrial structure and supply of finance type; and the driven by industrial structure, supply of finance, and supply of manpower type. (3) The paths to generate non-high green technology innovation efficiency can be summarized as one. The shortage of human resources and a poor economic environment are the main reasons for the inhibition of improvements in green technology innovation efficiency; additionally, the configuration of high and non-high green technology innovation efficiency is asymmetrical. On the one hand, our results are helpful for the study of the efficiency of regional green technology innovation at the provincial level. On the other hand, the results also provide practical solutions and a theoretical basis for provinces to promote regional green technology innovation efficiency under the new economic normal.

In this paper, the flexible solar wing support structure is taken as the research object, and the vibration is actively controlled by the piezoelectric material. In this paper, the Euler-Bernoulli beam theory is used to simplify the overall model structure. The principle of Language and the hypothetical modal method are used to derive the dynamic model of the piezoelectric flexible system. The obtained system dynamics model was simulated by PID control, and good results were obtained.