The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early...The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early experimental results of low-load and low-speed compressors;so,they may not be suitable for modern compressor performance estimations.In this study,several empirical models were reviewed,and two new models to estimate the minimum blade profile loss and minimum-loss deviation angle were established using mathematical statistics.Then,the original models with poor accuracy were replaced by these two models in through-flow program.Next,three compressors(Rotor 67,Stage 35,and a 4-stage repeating stage)were simulated using both the original and new models.The final results show that the new models have better accuracy in estimating the performance parameters than the original models.This indicates that it is feasible to use mathematical statistical methods to establish the empirical models,and this method provides an idea for the improvement of other empirical models in through-flow program.展开更多
目的观察老年超重行首次胃镜检查患者接受经鼻湿化高流量通气干预对其生命体征及低氧血症发生率的影响。方法依据干预方法不同,将2021年12月至2023年12月郑州市中医院的98例老年超重行首次胃镜检查患者平均分为两组,检查前,49例对照组...目的观察老年超重行首次胃镜检查患者接受经鼻湿化高流量通气干预对其生命体征及低氧血症发生率的影响。方法依据干预方法不同,将2021年12月至2023年12月郑州市中医院的98例老年超重行首次胃镜检查患者平均分为两组,检查前,49例对照组患者行常规鼻导管吸氧,49例观察组患者行经鼻湿化高流量通气,均干预到检查完毕,对比两组患者在检查期间的生命体征、苏醒时间、检查时间、低氧血症发生率及不良反应情况等。结果两组患者在麻醉前、插入胃镜后、苏醒时的心率和平均动脉压无统计学差异(P>0.05),观察组一次胃镜检查成功率高于对照组,检查和离院时间短于对照组(P<0.05),两组患者的苏醒时间无明显差异(P>0.05),观察组检查期间最低血氧饱和度(Saturation of Blood Oxygen,SpO2)较对照组高,低氧血症发生率较对照组低(P<0.05),两组患者的总不良反应发生率无统计学差异(P>0.05)。结论首次行胃镜检查的老年超重患者接受经鼻湿化高流量通气可有效维持镜检期间生命体征的稳定,缩短镜检及离院时间,提高一次检查的成功率,减少低氧血症的发生且较安全。展开更多
基金the National Natural Science Foundation of China for funding this work(Grant No.51676015).
文摘The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early experimental results of low-load and low-speed compressors;so,they may not be suitable for modern compressor performance estimations.In this study,several empirical models were reviewed,and two new models to estimate the minimum blade profile loss and minimum-loss deviation angle were established using mathematical statistics.Then,the original models with poor accuracy were replaced by these two models in through-flow program.Next,three compressors(Rotor 67,Stage 35,and a 4-stage repeating stage)were simulated using both the original and new models.The final results show that the new models have better accuracy in estimating the performance parameters than the original models.This indicates that it is feasible to use mathematical statistical methods to establish the empirical models,and this method provides an idea for the improvement of other empirical models in through-flow program.
文摘目的观察老年超重行首次胃镜检查患者接受经鼻湿化高流量通气干预对其生命体征及低氧血症发生率的影响。方法依据干预方法不同,将2021年12月至2023年12月郑州市中医院的98例老年超重行首次胃镜检查患者平均分为两组,检查前,49例对照组患者行常规鼻导管吸氧,49例观察组患者行经鼻湿化高流量通气,均干预到检查完毕,对比两组患者在检查期间的生命体征、苏醒时间、检查时间、低氧血症发生率及不良反应情况等。结果两组患者在麻醉前、插入胃镜后、苏醒时的心率和平均动脉压无统计学差异(P>0.05),观察组一次胃镜检查成功率高于对照组,检查和离院时间短于对照组(P<0.05),两组患者的苏醒时间无明显差异(P>0.05),观察组检查期间最低血氧饱和度(Saturation of Blood Oxygen,SpO2)较对照组高,低氧血症发生率较对照组低(P<0.05),两组患者的总不良反应发生率无统计学差异(P>0.05)。结论首次行胃镜检查的老年超重患者接受经鼻湿化高流量通气可有效维持镜检期间生命体征的稳定,缩短镜检及离院时间,提高一次检查的成功率,减少低氧血症的发生且较安全。
