目前开展的真实世界研究(real world study,RWS)仍存在诸多局限性,而未能在卫生技术评估方面充分发挥应有的作用。因此,有必要改进传统RWS设计,以产生高质量的医学证据。策略之一是仿照随机对照试验(randomized controlled trial,RCT)...目前开展的真实世界研究(real world study,RWS)仍存在诸多局限性,而未能在卫生技术评估方面充分发挥应有的作用。因此,有必要改进传统RWS设计,以产生高质量的医学证据。策略之一是仿照随机对照试验(randomized controlled trial,RCT)开展观察性研究(又称RCT仿真或模拟研究),既借鉴了RCT设计优势,增强了因果推断的强度,又保留了RWS的代表性,可以作为打通药品上市前与上市后证据链的桥梁,以期为医疗决策提供合理的证据支撑。仿照RCT开展观察性研究分为两步:第一步,基于临床问题构建一个目标试验,参照目标试验关键特征构建相应的RWS方案(包括纳排标准、治疗策略、分配程序、随访、结局定义、因果对比和统计分析策略),特别注意减小模拟差异和控制相关偏倚;第二步,使用真实世界数据(real world data,RWD)按照既定研究方案进行数据分析,得到相应结果。展开更多
The unique Coanda surface has a great influence on the performance of bladeless fan.However,there is few studies to explain the relationship between the performance and Coanda surface curvature at present.In order to ...The unique Coanda surface has a great influence on the performance of bladeless fan.However,there is few studies to explain the relationship between the performance and Coanda surface curvature at present.In order to gain a qualitative understanding of effect of the curvature on the performance of bladeless fan,numerical studies are performed in this paper.Firstly,three-dimensional numerical simulation is done by Fluent software.For the purpose to obtain detailed information of the flow field around the Coanda surface,two-dimensional numerical simulation is also conducted.Five types of Coanda surfaces with different curvature are designed,and the flow behaviour and the performance of them are analyzed and compared with those of the prototype.The analysis indicates that the curvature of Coanda surface is strongly related to blowing performance,It is found that there is an optimal curvature of Coanda surfaces among the studied models.Simulation result shows that there is a special low pressure region.With increasing curvature in Y direction,several low pressure regions gradually enlarged,then begin to merge slowly,and finally form a large area of low pressure.From the analyses of streamlines and velocity angle,it is found that the magnitude of the curvature affects the flow direction and reasonable curvature can induce fluid flow close to the wall.Thus,it leads to that the curvature of the streamlines is consistent with that of Coanda surface.Meanwhile,it also causes the fluid movement towards the most suitable direction.This study will provide useful information to performance improvements of bladeless fans.展开更多
文摘目前开展的真实世界研究(real world study,RWS)仍存在诸多局限性,而未能在卫生技术评估方面充分发挥应有的作用。因此,有必要改进传统RWS设计,以产生高质量的医学证据。策略之一是仿照随机对照试验(randomized controlled trial,RCT)开展观察性研究(又称RCT仿真或模拟研究),既借鉴了RCT设计优势,增强了因果推断的强度,又保留了RWS的代表性,可以作为打通药品上市前与上市后证据链的桥梁,以期为医疗决策提供合理的证据支撑。仿照RCT开展观察性研究分为两步:第一步,基于临床问题构建一个目标试验,参照目标试验关键特征构建相应的RWS方案(包括纳排标准、治疗策略、分配程序、随访、结局定义、因果对比和统计分析策略),特别注意减小模拟差异和控制相关偏倚;第二步,使用真实世界数据(real world data,RWD)按照既定研究方案进行数据分析,得到相应结果。
基金supported by National Natural Science Foundation of China(No.51276172)National Science and TechnologySupport Project(No.2013BAF05B01)
文摘The unique Coanda surface has a great influence on the performance of bladeless fan.However,there is few studies to explain the relationship between the performance and Coanda surface curvature at present.In order to gain a qualitative understanding of effect of the curvature on the performance of bladeless fan,numerical studies are performed in this paper.Firstly,three-dimensional numerical simulation is done by Fluent software.For the purpose to obtain detailed information of the flow field around the Coanda surface,two-dimensional numerical simulation is also conducted.Five types of Coanda surfaces with different curvature are designed,and the flow behaviour and the performance of them are analyzed and compared with those of the prototype.The analysis indicates that the curvature of Coanda surface is strongly related to blowing performance,It is found that there is an optimal curvature of Coanda surfaces among the studied models.Simulation result shows that there is a special low pressure region.With increasing curvature in Y direction,several low pressure regions gradually enlarged,then begin to merge slowly,and finally form a large area of low pressure.From the analyses of streamlines and velocity angle,it is found that the magnitude of the curvature affects the flow direction and reasonable curvature can induce fluid flow close to the wall.Thus,it leads to that the curvature of the streamlines is consistent with that of Coanda surface.Meanwhile,it also causes the fluid movement towards the most suitable direction.This study will provide useful information to performance improvements of bladeless fans.
