Unhealthy mental states have become common among teachers recently. Subjective physical symptoms are more likely to appear more readily than mental symptoms. In this study, we revealed that the relationship between me...Unhealthy mental states have become common among teachers recently. Subjective physical symptoms are more likely to appear more readily than mental symptoms. In this study, we revealed that the relationship between mental states and subjective physical fatigue or pain in seven body sites among 2449 teachers. The 12-item General Health Questionnaire (GHQ-12) was used to assess mental state. We defined a score of 4 points and over in the GHQ-12 score as unhealthy mental state. We also asked about the presence of subjective physical fatigue or pain in each seven body sites in the past one year. In the results, 30.3% unhealthy mental states were found in females and 22.9% in males. Most of subjective physical fatigue or pains were detected in neck and shoulder, eyes, head and low back. Using multivariate logistic regression, higher scores in the GHQ-12 were positively associated with presence of subjective fatigue or pain in head and eyes in both genders, in lower extremities among females, and in back, upper extremities among males. Our results suggest that physical symptoms in specific body sites with gender differences may be useful in the early identification of unhealthy mental states among teachers. We should have efforts to pay attention to mental states among high school teachers if their symptoms do not get better after taking physical care.展开更多
Based on initial discontinuity state (IDS) of material, a preliminary analytical model was presented to evaluate the effect of interaction of pitting corrosion and fatigue loading on the residual fatigue life of alumi...Based on initial discontinuity state (IDS) of material, a preliminary analytical model was presented to evaluate the effect of interaction of pitting corrosion and fatigue loading on the residual fatigue life of aluminum alloy LY12CZ. A life prediction was carried out using constant and variable amplitude loading for various pitting corrosion levels, and the prediction agreed reasonably with the available test data. The results suggest that the combination of a pit and IDS can be treated as the initial crack size. Pitting corrosion causes a significant decrease in fatigue lives with small corrosion depths. But the effect of pit on fatigue life is gradually reduced with increasing pit size. A pit with a constant depth can be applied to the model for long exposure structure. A preliminary recommendation for the pit depth is about 1 mm for LY12CZ. At last the effect of multiple-site corrosion damage (MSCD) on fatigue life was also studied, and the result shows that MSCD can decrease substantially fatigue life compared with that of a single crack.展开更多
The objects of our paper are aluminum alloy samples (AASs) contained the different amount of Cu, Mn, Mg, Si and Li. We are modeling the features of microstructure of potential relief of an AAS and studying its transfo...The objects of our paper are aluminum alloy samples (AASs) contained the different amount of Cu, Mn, Mg, Si and Li. We are modeling the features of microstructure of potential relief of an AAS and studying its transformation under both imposed fatigue deformation and wetted by liquid metals (Ga;or Hg;Li;In). We illustrate the main ideas by using only the “time series” allied with effective internal friction Q-1eff of an AAS. AASs like B-95 or 7075 are heterogeneous materials for which the more energy can be absorbed by selected micro-regions of a tested sample. So micro-crack in the space of AAS and alarm state of AAS arises. Each micro-region will to contribute the Q-1k (the internal friction Q-1k belong to k-th micro-region) to the effective internal friction— Q-1eff accordance with fit statistic . We find a number of micro-regions—L and series gk & Qk from the experimental data like as the internal friction (Q-1)eff versus both the number of cycles—N and the deformation—е. Series gk & Qk (k=1,2,3,...,L) present the microstructures of AASs. In this paper also is presented the original technology to forecast fatigue damage of an AAS. Here the fatigue sensitive element (FSE) used. We made multiphase heterogeneous mixtures (MHMs) which contents a variable volume of initial components. It is selected MHMs are using for produce FSEs. The present paper is aimed to establish the correlation of the FSEs microstructures changes and corresponding changes of the aluminum alloy microstructures at imposing the same spectra deformation on both of them. A change of FSEs microstructure investigated by using their effective electrical resistance Reff data.展开更多
为了提高呼吸信号判别驾驶疲劳的准确率,通过模拟驾驶试验探究呼吸信号与驾驶员疲劳状态的关系,提出呼吸疲劳节点的概念,并基于呼吸疲劳节点判别驾驶员的疲劳状态。首先,通过模拟驾驶试验采集驾驶员的呼吸信号,采用Karolinska嗜睡量表(K...为了提高呼吸信号判别驾驶疲劳的准确率,通过模拟驾驶试验探究呼吸信号与驾驶员疲劳状态的关系,提出呼吸疲劳节点的概念,并基于呼吸疲劳节点判别驾驶员的疲劳状态。首先,通过模拟驾驶试验采集驾驶员的呼吸信号,采用Karolinska嗜睡量表(Karolinska sleepiness scale, KSS)对疲劳程度进行主观自评量化。其次,把单位时间内眼睛闭合百分比(percentage of eyelid closure over the pupil over time, PERCLOS)作为参考,与主观自评反馈结合,对驾驶员呼吸疲劳节点进行标定。最后,基于呼吸疲劳节点利用随机树算法(random tree, RT)获得轻/重度呼吸疲劳变化节点的判别模型。结果表明:该模型能更加及时、准确地判别出驾驶员的疲劳状态;基于随机树算法获得的筛选条件对轻度呼吸疲劳变化节点识别的准确性要高于重度呼吸疲劳变化节点;轻/重度呼吸疲劳变化节点的平均识别误差分别为3.50 min和3.66 min,预测准确率分别为92.09%和92.03%。展开更多
文摘Unhealthy mental states have become common among teachers recently. Subjective physical symptoms are more likely to appear more readily than mental symptoms. In this study, we revealed that the relationship between mental states and subjective physical fatigue or pain in seven body sites among 2449 teachers. The 12-item General Health Questionnaire (GHQ-12) was used to assess mental state. We defined a score of 4 points and over in the GHQ-12 score as unhealthy mental state. We also asked about the presence of subjective physical fatigue or pain in each seven body sites in the past one year. In the results, 30.3% unhealthy mental states were found in females and 22.9% in males. Most of subjective physical fatigue or pains were detected in neck and shoulder, eyes, head and low back. Using multivariate logistic regression, higher scores in the GHQ-12 were positively associated with presence of subjective fatigue or pain in head and eyes in both genders, in lower extremities among females, and in back, upper extremities among males. Our results suggest that physical symptoms in specific body sites with gender differences may be useful in the early identification of unhealthy mental states among teachers. We should have efforts to pay attention to mental states among high school teachers if their symptoms do not get better after taking physical care.
基金Project(50675221) supported by the National Natural Science Foundation of China
文摘Based on initial discontinuity state (IDS) of material, a preliminary analytical model was presented to evaluate the effect of interaction of pitting corrosion and fatigue loading on the residual fatigue life of aluminum alloy LY12CZ. A life prediction was carried out using constant and variable amplitude loading for various pitting corrosion levels, and the prediction agreed reasonably with the available test data. The results suggest that the combination of a pit and IDS can be treated as the initial crack size. Pitting corrosion causes a significant decrease in fatigue lives with small corrosion depths. But the effect of pit on fatigue life is gradually reduced with increasing pit size. A pit with a constant depth can be applied to the model for long exposure structure. A preliminary recommendation for the pit depth is about 1 mm for LY12CZ. At last the effect of multiple-site corrosion damage (MSCD) on fatigue life was also studied, and the result shows that MSCD can decrease substantially fatigue life compared with that of a single crack.
文摘The objects of our paper are aluminum alloy samples (AASs) contained the different amount of Cu, Mn, Mg, Si and Li. We are modeling the features of microstructure of potential relief of an AAS and studying its transformation under both imposed fatigue deformation and wetted by liquid metals (Ga;or Hg;Li;In). We illustrate the main ideas by using only the “time series” allied with effective internal friction Q-1eff of an AAS. AASs like B-95 or 7075 are heterogeneous materials for which the more energy can be absorbed by selected micro-regions of a tested sample. So micro-crack in the space of AAS and alarm state of AAS arises. Each micro-region will to contribute the Q-1k (the internal friction Q-1k belong to k-th micro-region) to the effective internal friction— Q-1eff accordance with fit statistic . We find a number of micro-regions—L and series gk & Qk from the experimental data like as the internal friction (Q-1)eff versus both the number of cycles—N and the deformation—е. Series gk & Qk (k=1,2,3,...,L) present the microstructures of AASs. In this paper also is presented the original technology to forecast fatigue damage of an AAS. Here the fatigue sensitive element (FSE) used. We made multiphase heterogeneous mixtures (MHMs) which contents a variable volume of initial components. It is selected MHMs are using for produce FSEs. The present paper is aimed to establish the correlation of the FSEs microstructures changes and corresponding changes of the aluminum alloy microstructures at imposing the same spectra deformation on both of them. A change of FSEs microstructure investigated by using their effective electrical resistance Reff data.
文摘为了提高呼吸信号判别驾驶疲劳的准确率,通过模拟驾驶试验探究呼吸信号与驾驶员疲劳状态的关系,提出呼吸疲劳节点的概念,并基于呼吸疲劳节点判别驾驶员的疲劳状态。首先,通过模拟驾驶试验采集驾驶员的呼吸信号,采用Karolinska嗜睡量表(Karolinska sleepiness scale, KSS)对疲劳程度进行主观自评量化。其次,把单位时间内眼睛闭合百分比(percentage of eyelid closure over the pupil over time, PERCLOS)作为参考,与主观自评反馈结合,对驾驶员呼吸疲劳节点进行标定。最后,基于呼吸疲劳节点利用随机树算法(random tree, RT)获得轻/重度呼吸疲劳变化节点的判别模型。结果表明:该模型能更加及时、准确地判别出驾驶员的疲劳状态;基于随机树算法获得的筛选条件对轻度呼吸疲劳变化节点识别的准确性要高于重度呼吸疲劳变化节点;轻/重度呼吸疲劳变化节点的平均识别误差分别为3.50 min和3.66 min,预测准确率分别为92.09%和92.03%。
