Evidence on the lifetime risk for atherosclerotic cardiovascular disease （ASCVD） is insufficient; yet, estimating an individual＇s lifetime risk allows for a comprehensive assessment of ASCVD burden. We developed an...Evidence on the lifetime risk for atherosclerotic cardiovascular disease （ASCVD） is insufficient; yet, estimating an individual＇s lifetime risk allows for a comprehensive assessment of ASCVD burden. We developed and validated lifetime risk prediction equations for ASCVD using four large and ongoing prospective cohorts of Chinese, the China-PAR project （Prediction for ASCVD Risk in China）. Sexspecific equations were developed using two cohorts （as the derivation cohort） of 21,320 participants. Two other independent cohorts with 14,123 and 70,838 participants were used for their external valida- tion, respectively. We evaluated both calibration and discrimination measures for model performance. Furthermore, we estimated ASCVD-ffee years lost or excess absolute risk attributable to high 10-year risk （≥10.0%） and]or high lifetime risk （≥32.8%）. After 12.3 years＇ follow-up of the derivation cohort, 1048 ASCVD events and 1304 non-ASCVD deaths were identified. Our sex-specific equations had good internal validation, with discriminant C statistics of 0.776 （95% confidence interval [CI]： 0.757-0.794） and 0.801 （95% CI： 0.778-0.825）, and calibration Z2 of 9.2 （P = 0.418） and 5.6 （P = 0.777） for men and women, respectively. Good external validation was also demonstrated with predicted rates closely matched to the observed ones. Compared with men having both low 10-year and low lifetime risk, men would develop ASCVD 3.0, 4.6 and 8.6 years earlier if they had high 10-year risk alone, high lifetime risk alone, or both high 10-year and high lifetime risk at the index age of 35 years, respectively. We developed well- performed lifetime risk prediction equations that will help to identify those with the greatest potential to avert ASCVD burden after implementation of innovative clinical and public health interventions in China.展开更多
针对基于寿命数据的预测方法效率不高的问题,在进行温、湿度双应力加速退化试验的基础上,研究了通过分析加速退化数据而进行寿命预测的途径.为了充分利用所收集的产品寿命数据来提高预测精度,提出了综合退化数据与寿命数据的寿命预测方...针对基于寿命数据的预测方法效率不高的问题,在进行温、湿度双应力加速退化试验的基础上,研究了通过分析加速退化数据而进行寿命预测的途径.为了充分利用所收集的产品寿命数据来提高预测精度,提出了综合退化数据与寿命数据的寿命预测方法.分别使用Wiener过程、逆高斯分布和广义Eyring模型对产品性能的退化数据、少量寿命数据以及产品反应率进行建模,并建立了综合以上信息的可靠性模型.在此基础上,利用Markov Chain Monte Carlo仿真方法得到模型参数的点估计值,通过Bootstrap自助抽样法获得了模型参数的估计区间.结果表明,所提出的综合退化数据与寿命数据的方法可以提高寿命预测精度.展开更多
动量轮是卫星姿态控制系统的关键部件,对卫星的可靠性及整体寿命有直接影响。针对卫星动量轮的剩余寿命预测问题,提出一种基于Copula函数的多退化量下的寿命预测方法。首先,分析了影响动量轮寿命的关键因素,选择润滑剂剩余量和电流作为...动量轮是卫星姿态控制系统的关键部件,对卫星的可靠性及整体寿命有直接影响。针对卫星动量轮的剩余寿命预测问题,提出一种基于Copula函数的多退化量下的寿命预测方法。首先,分析了影响动量轮寿命的关键因素,选择润滑剂剩余量和电流作为退化量;其次,分别对单个退化量进行退化建模,得到动量轮剩余寿命的边缘分布函数;然后,通过Copula函数族来描述多退化量之间的相关性,并对边缘分布进行融合,得到动量轮剩余寿命的联合分布函数;最后,提出基于赤池信息准则(Akaike information criterion,AIC)模型评价的Copula函数选择方法。展开更多
The Manson-Coffin equation has been widely applied to the prediction of fatigue lifetime.But this equation does not explicitly express the relation between the fatigue lifetime and the crack length.The present paper p...The Manson-Coffin equation has been widely applied to the prediction of fatigue lifetime.But this equation does not explicitly express the relation between the fatigue lifetime and the crack length.The present paper proposes that the grain size can be re-placed by the maximum non-damaging crack length.Thus,the growth rate will decrease to zero when the crack reaches this size.Combining with the theory of the fatigue short crack propagation,we derived the relations between physically short crack's initiation-propagation rates and material's mechanical properties,as well as crack length,stress and strain.With the derived relations,fatigue lifetime of short cracks can be successfully predicted by basic mechanical properties.Similar to the format of Manson-Coffin equation,our relations uncover the essence of Manson-Coffin equation which may reveal the short crack's initiation-propagation mechanism.Predictions of fatigue lifetime using our relations were compared with the results of well-known experiments.Good agreement is found in many aspects,such as coefficients,exponents,as well as fatigue life-times,especially for short cracks around 10 micrometers.Predictions on the short crack propagation rates are also compared for 16 types of carbon steels.Satisfactory consistency shows that our relations have wide applicability.展开更多
基金supported by the CAMS Innovation Fund for Medical Sciences(2017-I2M-1-004)the Ministry of Science and Technology of China(2017YFC0211700,2011BAI11B03,2011BAI09B03,and 2006BAI01A01)the National Natural Science Foundation of China(91643208)
文摘Evidence on the lifetime risk for atherosclerotic cardiovascular disease （ASCVD） is insufficient; yet, estimating an individual＇s lifetime risk allows for a comprehensive assessment of ASCVD burden. We developed and validated lifetime risk prediction equations for ASCVD using four large and ongoing prospective cohorts of Chinese, the China-PAR project （Prediction for ASCVD Risk in China）. Sexspecific equations were developed using two cohorts （as the derivation cohort） of 21,320 participants. Two other independent cohorts with 14,123 and 70,838 participants were used for their external valida- tion, respectively. We evaluated both calibration and discrimination measures for model performance. Furthermore, we estimated ASCVD-ffee years lost or excess absolute risk attributable to high 10-year risk （≥10.0%） and]or high lifetime risk （≥32.8%）. After 12.3 years＇ follow-up of the derivation cohort, 1048 ASCVD events and 1304 non-ASCVD deaths were identified. Our sex-specific equations had good internal validation, with discriminant C statistics of 0.776 （95% confidence interval [CI]： 0.757-0.794） and 0.801 （95% CI： 0.778-0.825）, and calibration Z2 of 9.2 （P = 0.418） and 5.6 （P = 0.777） for men and women, respectively. Good external validation was also demonstrated with predicted rates closely matched to the observed ones. Compared with men having both low 10-year and low lifetime risk, men would develop ASCVD 3.0, 4.6 and 8.6 years earlier if they had high 10-year risk alone, high lifetime risk alone, or both high 10-year and high lifetime risk at the index age of 35 years, respectively. We developed well- performed lifetime risk prediction equations that will help to identify those with the greatest potential to avert ASCVD burden after implementation of innovative clinical and public health interventions in China.
文摘针对基于寿命数据的预测方法效率不高的问题,在进行温、湿度双应力加速退化试验的基础上,研究了通过分析加速退化数据而进行寿命预测的途径.为了充分利用所收集的产品寿命数据来提高预测精度,提出了综合退化数据与寿命数据的寿命预测方法.分别使用Wiener过程、逆高斯分布和广义Eyring模型对产品性能的退化数据、少量寿命数据以及产品反应率进行建模,并建立了综合以上信息的可靠性模型.在此基础上,利用Markov Chain Monte Carlo仿真方法得到模型参数的点估计值,通过Bootstrap自助抽样法获得了模型参数的估计区间.结果表明,所提出的综合退化数据与寿命数据的方法可以提高寿命预测精度.
文摘动量轮是卫星姿态控制系统的关键部件,对卫星的可靠性及整体寿命有直接影响。针对卫星动量轮的剩余寿命预测问题,提出一种基于Copula函数的多退化量下的寿命预测方法。首先,分析了影响动量轮寿命的关键因素,选择润滑剂剩余量和电流作为退化量;其次,分别对单个退化量进行退化建模,得到动量轮剩余寿命的边缘分布函数;然后,通过Copula函数族来描述多退化量之间的相关性,并对边缘分布进行融合,得到动量轮剩余寿命的联合分布函数;最后,提出基于赤池信息准则(Akaike information criterion,AIC)模型评价的Copula函数选择方法。
文摘The Manson-Coffin equation has been widely applied to the prediction of fatigue lifetime.But this equation does not explicitly express the relation between the fatigue lifetime and the crack length.The present paper proposes that the grain size can be re-placed by the maximum non-damaging crack length.Thus,the growth rate will decrease to zero when the crack reaches this size.Combining with the theory of the fatigue short crack propagation,we derived the relations between physically short crack's initiation-propagation rates and material's mechanical properties,as well as crack length,stress and strain.With the derived relations,fatigue lifetime of short cracks can be successfully predicted by basic mechanical properties.Similar to the format of Manson-Coffin equation,our relations uncover the essence of Manson-Coffin equation which may reveal the short crack's initiation-propagation mechanism.Predictions of fatigue lifetime using our relations were compared with the results of well-known experiments.Good agreement is found in many aspects,such as coefficients,exponents,as well as fatigue life-times,especially for short cracks around 10 micrometers.Predictions on the short crack propagation rates are also compared for 16 types of carbon steels.Satisfactory consistency shows that our relations have wide applicability.
