在API RP 581-2016和GB/T 26610.4-2014中对换热器管束失效概率的计算都是基于威布尔概率统计方法,但其计算过程有较大区别。出于工程应用的考虑,GB/T 26610.4中威布尔概率统计公式的参数选取较简单,并没有像API RP 581中给出其它的参...在API RP 581-2016和GB/T 26610.4-2014中对换热器管束失效概率的计算都是基于威布尔概率统计方法,但其计算过程有较大区别。出于工程应用的考虑,GB/T 26610.4中威布尔概率统计公式的参数选取较简单,并没有像API RP 581中给出其它的参数选取方式。文章采用威布尔双参数和三参数计算模型对示例换热器管束进行了失效概率计算,同标准计算结果进行对比发现:GB/T 26610.4中的计算方法拟合效果较差。同时提出了基于设计参数确定η参数的取值方法,并将其应用于示例计算,得到了拟合程度近似于GB/T 26610.4中的计算方法,可以用于换热管束失效概率计算。展开更多
Aim To quantitatively study three characteristics of the Weibull distribution. Methods Theoritical analysis of the three characteristics of parameters of the Weibull distribution was done and mathematics software wa...Aim To quantitatively study three characteristics of the Weibull distribution. Methods Theoritical analysis of the three characteristics of parameters of the Weibull distribution was done and mathematics software was used to make some chart analysis. Results 17 equations and 7 figures were made. Conclusion Under the standard form, the class of the Weibull probable density founction(pdf) curves appear double peak shape. Under the standard form, the maximum value point curve of the Weibull pdf takes line t =0 and t=1 as asymptotes. When β = 3 30-3 40, the Weibull distribution is the most similar to the normal distribution.展开更多
This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ ...This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ observations from the RACORO field campaign （the routine atmospheric radiation measurement aerial facility clouds with low optical water depths optical radiative observations） over the atmospheric radiation measurement Southern Great Plains site, USA. The result shows that the mean entrainment rate of all the 186 clouds systematically decreases from the cloud edge to the cloud center. Further analysis of the fluctuation of entrainment rate shows that the probability density function of entrainment rate in each flight can be fitted by the lognormal, gamma, or Weibull distributions virtually equally well, with the Weibull dis- tribution being the best. The parameter ＂standard devia- tion＂ in the lognormal distribution is weakly negatively correlated, and the other parameters in the three distribu- tions are positively correlated with relative humidity in the entrained dry air and dilution effect, respectively. Entrainment rate is negatively correlated with droplet concentration, droplet size, and liquid water content, but positively correlated with relative dispersion. The effect of entrainment rate on the spectral shape of cloud droplet size distribution is examined and linked to the systems theory on the cloud droplet size distribution.展开更多
文摘在API RP 581-2016和GB/T 26610.4-2014中对换热器管束失效概率的计算都是基于威布尔概率统计方法,但其计算过程有较大区别。出于工程应用的考虑,GB/T 26610.4中威布尔概率统计公式的参数选取较简单,并没有像API RP 581中给出其它的参数选取方式。文章采用威布尔双参数和三参数计算模型对示例换热器管束进行了失效概率计算,同标准计算结果进行对比发现:GB/T 26610.4中的计算方法拟合效果较差。同时提出了基于设计参数确定η参数的取值方法,并将其应用于示例计算,得到了拟合程度近似于GB/T 26610.4中的计算方法,可以用于换热管束失效概率计算。
文摘Aim To quantitatively study three characteristics of the Weibull distribution. Methods Theoritical analysis of the three characteristics of parameters of the Weibull distribution was done and mathematics software was used to make some chart analysis. Results 17 equations and 7 figures were made. Conclusion Under the standard form, the class of the Weibull probable density founction(pdf) curves appear double peak shape. Under the standard form, the maximum value point curve of the Weibull pdf takes line t =0 and t=1 as asymptotes. When β = 3 30-3 40, the Weibull distribution is the most similar to the normal distribution.
基金supported by the National Natural Science Foundation of China(41305120,91337215)the Research Foundation for Environmental Protection of Jiangsu Province(2013042)+9 种基金the Natural Science Foundation of Jiangsu Province,China(BK20130988)the Specialized Research Foundation for the Doctoral Program of Higher Education(20133228120002)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(13KJB170014)China Meteorological Administration Special Public Welfare Research Foundation(GYHY201406007)the Open Funding from State Key Laboratory of Severe Weather(2013LASW-B06)the Open Funding from Key Laboratory of Meteorological Disaster of Ministry of Education,China(KLME1305)the Qing Lan Projecta Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe US Department of Energy’s(DOE)Earth System Modeling(ESM)program via the FASTER project(www.bnl.gov/faster)Atmospheric System Research(ASR)Program
文摘This paper focuses on the variability in entrainment rate in individual cumulus clouds using the entrainment rate estimated on the scale of 5 m in 186 shallow cumulus clouds from eight aircraft flights, using in situ observations from the RACORO field campaign （the routine atmospheric radiation measurement aerial facility clouds with low optical water depths optical radiative observations） over the atmospheric radiation measurement Southern Great Plains site, USA. The result shows that the mean entrainment rate of all the 186 clouds systematically decreases from the cloud edge to the cloud center. Further analysis of the fluctuation of entrainment rate shows that the probability density function of entrainment rate in each flight can be fitted by the lognormal, gamma, or Weibull distributions virtually equally well, with the Weibull dis- tribution being the best. The parameter ＂standard devia- tion＂ in the lognormal distribution is weakly negatively correlated, and the other parameters in the three distribu- tions are positively correlated with relative humidity in the entrained dry air and dilution effect, respectively. Entrainment rate is negatively correlated with droplet concentration, droplet size, and liquid water content, but positively correlated with relative dispersion. The effect of entrainment rate on the spectral shape of cloud droplet size distribution is examined and linked to the systems theory on the cloud droplet size distribution.
