Objective This study aimed to determine the temporal trends in sleep duration among Chinese adults.Methods In this series of repeated nationally representative cross-sectional surveys(China Chronic Disease and Risk Fa...Objective This study aimed to determine the temporal trends in sleep duration among Chinese adults.Methods In this series of repeated nationally representative cross-sectional surveys(China Chronic Disease and Risk Factors Surveillance)conducted between 2010 and 2018,a total of 645,420 adult participants(97,741 in 2010;175,749 in 2013;187,777 in 2015;and 184,153 in 2018)were included in the trend analysis.Linear and logistic regression models were utilized to assess trends in sleep duration.Results In 2018,the estimated overall mean sleep duration among the Chinese adult population was7.58(SD,1.45)hours per day,with no significant trend from 2010.A significant increase in short sleep duration(≤6 hours)was observed in the total population,from 15.3%(95%CI:14.1%–16.5%)in 2010 to18.5%(95%CI:17.7%–19.3%)in 2018(P<0.001).Similarly,the trend in long sleep duration(>9 hours)was also significant,increasing in weighted prevalence from 7.2%(95%CI:6.3%–8.1%)in 2010 to 9.0%(95%CI:8.2%–9.9%)in 2018(P<0.001).Conclusion The prevalence of both short and long sleep durations significantly increased among Chinese adults from 2010 to 2018,highlighting the urgency of health initiatives to promote optimal sleep duration in China.展开更多
In this study, a numerical representative volume element (RVE) model was used to predict the mechanical properties of a Rice Husk Particulate (RHP)-Epoxy composite for use as an alternative material in non-critical ap...In this study, a numerical representative volume element (RVE) model was used to predict the mechanical properties of a Rice Husk Particulate (RHP)-Epoxy composite for use as an alternative material in non-critical applications. Seven different analytical models Counto, Ishai-Cohen, Halpin-Tsai, Nielsen, Nicolais, Modified Nicolais and Pukanszky were used as comparison tools for the numerical model. RHP-Epoxy biocomposite samples were fabricated with 0%, 10% and 30% RHP volume percentage and the experimental results benchmarked against the numerical and analytical projections. The mechanical properties estimated for 0%, 10% and 30% RHP-Epoxy composites using the numerical and analytical models were in general agreement. Using the analytical models, it was calculated that an increase in volume percentage of RHP to 30% led to continual reduction in elastic Young’s modulus and ultimate tensile strength of the composite. The numerical RVE models also predicted a similar trend between filler volume percentage and material properties. These projections were consistent with the experimental results whereby a 10% increase in RHP content led to 15% and 20% decrease in yield stress and tensile strength, but had no effect on the composite’s elastic property. Further increase in RHP volume percentage to 30% resulted in 8%, 21% and 28% reduction in Young’s modulus, yield stress and tensile strength, respectively. Overall, the results of this study suggest that RHP can be used to reduce the composite raw material costs by replacing the more expensive polymer content with agricultural waste products with limited compromise to the composite’s mechanical properties.展开更多
The present study proposes a modified random sequential absorption(RSA)algorithm to generate a representative volume element(RVE)model for predicting the elastic properties of discontinuous curved fiber reinforced com...The present study proposes a modified random sequential absorption(RSA)algorithm to generate a representative volume element(RVE)model for predicting the elastic properties of discontinuous curved fiber reinforced composites(DCFRCs)with varying fiber waviness functions and orientations.A small-move method was proposed to modify the traditional RSA algorithm.In comparison with the original RSA algorithm,the generation efficiency of the proposed modified RSA algorithm increased by over 40%,and the achievable maximum fiber volume fraction could reach up to 15%with a fiber aspect ratio of 15.The generated RVE model was utilized in conducting finite element analysis to investigate the effect of fiber waviness and wavy functions on the elastic properties of DCFRCs.Finally,a modified rule-of-mixture was proposed to predict the elastic properties of DCFRCs with various fiber orientations.The results indicated that the elastic properties predicted by the modified rule-of-mixture were in good agreement with those obtained from the RVE model,thereby demonstrating its effectiveness.展开更多
In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mounta...In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mountain,renowned for the musical sounds produced by wind-blown sands when the wind blows,stood in silent majesty.To the close north of the mountain's massive golden dunes stood the city's international convention centre,where some 400 vips from 60 countries host cultural exchanges and mutual learning.展开更多
基金supported by the National Natural Science Foundation of China(82341245,82371491)the Chinese Central Government(Key Project of Public Health Program)the National Key Research and Development Program of China(2018YFC1311706,2018YFC1311702)。
文摘Objective This study aimed to determine the temporal trends in sleep duration among Chinese adults.Methods In this series of repeated nationally representative cross-sectional surveys(China Chronic Disease and Risk Factors Surveillance)conducted between 2010 and 2018,a total of 645,420 adult participants(97,741 in 2010;175,749 in 2013;187,777 in 2015;and 184,153 in 2018)were included in the trend analysis.Linear and logistic regression models were utilized to assess trends in sleep duration.Results In 2018,the estimated overall mean sleep duration among the Chinese adult population was7.58(SD,1.45)hours per day,with no significant trend from 2010.A significant increase in short sleep duration(≤6 hours)was observed in the total population,from 15.3%(95%CI:14.1%–16.5%)in 2010 to18.5%(95%CI:17.7%–19.3%)in 2018(P<0.001).Similarly,the trend in long sleep duration(>9 hours)was also significant,increasing in weighted prevalence from 7.2%(95%CI:6.3%–8.1%)in 2010 to 9.0%(95%CI:8.2%–9.9%)in 2018(P<0.001).Conclusion The prevalence of both short and long sleep durations significantly increased among Chinese adults from 2010 to 2018,highlighting the urgency of health initiatives to promote optimal sleep duration in China.
文摘In this study, a numerical representative volume element (RVE) model was used to predict the mechanical properties of a Rice Husk Particulate (RHP)-Epoxy composite for use as an alternative material in non-critical applications. Seven different analytical models Counto, Ishai-Cohen, Halpin-Tsai, Nielsen, Nicolais, Modified Nicolais and Pukanszky were used as comparison tools for the numerical model. RHP-Epoxy biocomposite samples were fabricated with 0%, 10% and 30% RHP volume percentage and the experimental results benchmarked against the numerical and analytical projections. The mechanical properties estimated for 0%, 10% and 30% RHP-Epoxy composites using the numerical and analytical models were in general agreement. Using the analytical models, it was calculated that an increase in volume percentage of RHP to 30% led to continual reduction in elastic Young’s modulus and ultimate tensile strength of the composite. The numerical RVE models also predicted a similar trend between filler volume percentage and material properties. These projections were consistent with the experimental results whereby a 10% increase in RHP content led to 15% and 20% decrease in yield stress and tensile strength, but had no effect on the composite’s elastic property. Further increase in RHP volume percentage to 30% resulted in 8%, 21% and 28% reduction in Young’s modulus, yield stress and tensile strength, respectively. Overall, the results of this study suggest that RHP can be used to reduce the composite raw material costs by replacing the more expensive polymer content with agricultural waste products with limited compromise to the composite’s mechanical properties.
基金supported by the Liaoning Science and Technology Program“Open Bidding for Selecting the Best Candidates”Project,China(Grant No.2022JH1/10400043)Shanghai Science and Technology Innovation Action Plan,China(Grant No.22511102600)sponsored by Shanghai Gaofeng Project for University Academic Program Development。
文摘The present study proposes a modified random sequential absorption(RSA)algorithm to generate a representative volume element(RVE)model for predicting the elastic properties of discontinuous curved fiber reinforced composites(DCFRCs)with varying fiber waviness functions and orientations.A small-move method was proposed to modify the traditional RSA algorithm.In comparison with the original RSA algorithm,the generation efficiency of the proposed modified RSA algorithm increased by over 40%,and the achievable maximum fiber volume fraction could reach up to 15%with a fiber aspect ratio of 15.The generated RVE model was utilized in conducting finite element analysis to investigate the effect of fiber waviness and wavy functions on the elastic properties of DCFRCs.Finally,a modified rule-of-mixture was proposed to predict the elastic properties of DCFRCs with various fiber orientations.The results indicated that the elastic properties predicted by the modified rule-of-mixture were in good agreement with those obtained from the RVE model,thereby demonstrating its effectiveness.
文摘In late May,the city of Dunhuang,a key historical hub of Eastern and Western cultures in Northwest China's Gansu Province,basked in clear and refreshing weather under a brilliant blue sky.The rugged Mingsha Mountain,renowned for the musical sounds produced by wind-blown sands when the wind blows,stood in silent majesty.To the close north of the mountain's massive golden dunes stood the city's international convention centre,where some 400 vips from 60 countries host cultural exchanges and mutual learning.
