The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events. The study of spatial distribution and temporal trend of precipitation in river basins has been paid mo...The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events. The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention. However, in China, the precipitation data are measured by weather stations （WS） of China Meteorological Administration and hydrological rain gauges （RG） of national and local hydrology bureau. The WS data usually have long record with fewer stations, while the RG data usually have short record with more stations. The consistency and correlation of these two data sets have not been well understood. In this paper, the precipitation data from 30 weather stations for 1958-2007 and 248 rain gauges for 1995-2004 in the Haihe River basin are examined and compared using linear regression, 5-year moving average, Mann-Kendall trend analysis, Kolmogorov-Smirnov test, Z test and F test methods. The results show that the annual precipitation from both WS and RG records are normally distributed with minor difference in the mean value and variance. It is statistically feasible to extend the precipitation of RG by WS data sets. Using the extended precipitation data, the detailed spatial distribution of the annual and seasonal precipitation amounts as well as their temporal trends are calculated and mapped. The various distribution maps produced in the study show that for the whole basin the precipitation of 1958-2007 has been decreasing except for spring season. The decline trend is significant in summer, and this trend is stronger after the 1980s. The annual and seasonal precipitation amounts and changing trends are different in different regions and seasons. The precipitation is decreasing from south to north, from coastal zone to inland area.展开更多
目的提出一种建立在医疗设备故障数据集的医疗设备可靠性分析方法,为医疗设备预防性维护策略研究提供参考。方法收集2017—2020年华东地区三级医院呼吸机、麻醉机、消化道内镜与血液透析机故障数据作为实验集,收集同期温州市中医院、温...目的提出一种建立在医疗设备故障数据集的医疗设备可靠性分析方法,为医疗设备预防性维护策略研究提供参考。方法收集2017—2020年华东地区三级医院呼吸机、麻醉机、消化道内镜与血液透析机故障数据作为实验集,收集同期温州市中医院、温州市中心医院医疗设备故障数据作为测试集,在收集的设备故障数据集的基础上建立并计算Logistic分布函数,并从医疗设备失效密度、可靠性、失效率、平均首次故障时间(Mean First Time Failures,MFTF)等方面进行分析。结果实验集医疗设备故障频率趋于尾重峰高的类正态分布;四种故障实验集Logistic分布函数拟合优度值分别为0.91、0.85、0.87、0.89,对应P值分别为0.87、0.54、0.61、0.72,接受原假设,设备故障实验集符合Logistic分布;四种故障数据集Kolmogorov-Smirnov(KS)检验P值分别为0.35、0.25、0.11、0.42,实验集和测试集服从统一分布;四种设备MFTF值分别为1233.8、1733.8、779.2、1003.6 d。结论建立的Logistic分布函数可有效反映设备故障分布,可根据可靠性计算结果适时调整医院医疗设备预防性维护策略,值得进一步研究和推广。展开更多
基金National Basic Research Program of China, No.2010CB428406 The Key Knowledge Innovation Project of the CAS, No.KZCX2-YW-126 Key Project of National Natural Science Foundation of China, No.40730632
文摘The seasonal variability and spatial distribution of precipitation are the main cause of flood and drought events. The study of spatial distribution and temporal trend of precipitation in river basins has been paid more and more attention. However, in China, the precipitation data are measured by weather stations （WS） of China Meteorological Administration and hydrological rain gauges （RG） of national and local hydrology bureau. The WS data usually have long record with fewer stations, while the RG data usually have short record with more stations. The consistency and correlation of these two data sets have not been well understood. In this paper, the precipitation data from 30 weather stations for 1958-2007 and 248 rain gauges for 1995-2004 in the Haihe River basin are examined and compared using linear regression, 5-year moving average, Mann-Kendall trend analysis, Kolmogorov-Smirnov test, Z test and F test methods. The results show that the annual precipitation from both WS and RG records are normally distributed with minor difference in the mean value and variance. It is statistically feasible to extend the precipitation of RG by WS data sets. Using the extended precipitation data, the detailed spatial distribution of the annual and seasonal precipitation amounts as well as their temporal trends are calculated and mapped. The various distribution maps produced in the study show that for the whole basin the precipitation of 1958-2007 has been decreasing except for spring season. The decline trend is significant in summer, and this trend is stronger after the 1980s. The annual and seasonal precipitation amounts and changing trends are different in different regions and seasons. The precipitation is decreasing from south to north, from coastal zone to inland area.
文摘目的提出一种建立在医疗设备故障数据集的医疗设备可靠性分析方法,为医疗设备预防性维护策略研究提供参考。方法收集2017—2020年华东地区三级医院呼吸机、麻醉机、消化道内镜与血液透析机故障数据作为实验集,收集同期温州市中医院、温州市中心医院医疗设备故障数据作为测试集,在收集的设备故障数据集的基础上建立并计算Logistic分布函数,并从医疗设备失效密度、可靠性、失效率、平均首次故障时间(Mean First Time Failures,MFTF)等方面进行分析。结果实验集医疗设备故障频率趋于尾重峰高的类正态分布;四种故障实验集Logistic分布函数拟合优度值分别为0.91、0.85、0.87、0.89,对应P值分别为0.87、0.54、0.61、0.72,接受原假设,设备故障实验集符合Logistic分布;四种故障数据集Kolmogorov-Smirnov(KS)检验P值分别为0.35、0.25、0.11、0.42,实验集和测试集服从统一分布;四种设备MFTF值分别为1233.8、1733.8、779.2、1003.6 d。结论建立的Logistic分布函数可有效反映设备故障分布,可根据可靠性计算结果适时调整医院医疗设备预防性维护策略,值得进一步研究和推广。
