Irregular shape catalysts with through-holes are new type catalysts developed recently. They are helpful to modify heat transfer character and to decrease the pressure drop of the fixed bed. This paper studied the inf...Irregular shape catalysts with through-holes are new type catalysts developed recently. They are helpful to modify heat transfer character and to decrease the pressure drop of the fixed bed. This paper studied the influence of irregular shape catalysts with through-holes on the pressure drop of the fixed bed and determined the equivalent diameter of irregular shape catalysts with through-holes. The equivalent diameter can be obtained by determining the pressure drop of the fixed bed packed with a certain catalyst. Equipment used to determine the equivalent diameters of catalysts is established. The equivalent diameters of three irregular shape catalysts were determined by Ergun equation.展开更多
目的探讨扫描野(Scanning Field of View,SFOV)对成人胸部CT水当量直径的体型特异性剂量估算(Water Equivalent Diameter of Size-Specific Dose Estimates,SSDE_(WED))的影响。方法回顾性分析2020年7至8月我院行胸部CT扫描的162例成人...目的探讨扫描野(Scanning Field of View,SFOV)对成人胸部CT水当量直径的体型特异性剂量估算(Water Equivalent Diameter of Size-Specific Dose Estimates,SSDE_(WED))的影响。方法回顾性分析2020年7至8月我院行胸部CT扫描的162例成人受检者,选取原始序列横断位中间层面图像,勾画圆形感兴趣区(Region of Interest,ROI),测量ROI的CT_(ROI)值、面积A_(ROI),记录受检者的性别、年龄、容积剂量指数(Volume CT Dose Index,CTDI_(vol))、剂量长度乘积(Dose Length Product,DLP)和SFOV的数值,计算每例受检者中间层面的水等效直径(Water Equivalent Diameter,WED)、转换因子(f_(size·WED))和SSDE_(WED)。利用多元回归分析性别、年龄、CT_(ROI)、A_(ROI)、CTDI_(vol)、DLP和SFOV与SSDE_(WED)的相关性。结果性别、年龄、A_(ROI)、CTDI_(vol)、DLP和SFOV与SSDE_(WED)有显著差异(P<0.05),CT_(ROI)与SSDE_(WED)无显著差异(P>0.05),多元回归分析SSDE_(WED)与SFOV呈0.06倍正线性相关。结论SFOV对成人胸部CT的SSDE_(WED)影响较大,且呈0.06倍正线性相关,在临床扫描中精准调节SFOV可以降低成人受检者胸部CT辐射剂量。展开更多
文摘Irregular shape catalysts with through-holes are new type catalysts developed recently. They are helpful to modify heat transfer character and to decrease the pressure drop of the fixed bed. This paper studied the influence of irregular shape catalysts with through-holes on the pressure drop of the fixed bed and determined the equivalent diameter of irregular shape catalysts with through-holes. The equivalent diameter can be obtained by determining the pressure drop of the fixed bed packed with a certain catalyst. Equipment used to determine the equivalent diameters of catalysts is established. The equivalent diameters of three irregular shape catalysts were determined by Ergun equation.
文摘目的探讨扫描野(Scanning Field of View,SFOV)对成人胸部CT水当量直径的体型特异性剂量估算(Water Equivalent Diameter of Size-Specific Dose Estimates,SSDE_(WED))的影响。方法回顾性分析2020年7至8月我院行胸部CT扫描的162例成人受检者,选取原始序列横断位中间层面图像,勾画圆形感兴趣区(Region of Interest,ROI),测量ROI的CT_(ROI)值、面积A_(ROI),记录受检者的性别、年龄、容积剂量指数(Volume CT Dose Index,CTDI_(vol))、剂量长度乘积(Dose Length Product,DLP)和SFOV的数值,计算每例受检者中间层面的水等效直径(Water Equivalent Diameter,WED)、转换因子(f_(size·WED))和SSDE_(WED)。利用多元回归分析性别、年龄、CT_(ROI)、A_(ROI)、CTDI_(vol)、DLP和SFOV与SSDE_(WED)的相关性。结果性别、年龄、A_(ROI)、CTDI_(vol)、DLP和SFOV与SSDE_(WED)有显著差异(P<0.05),CT_(ROI)与SSDE_(WED)无显著差异(P>0.05),多元回归分析SSDE_(WED)与SFOV呈0.06倍正线性相关。结论SFOV对成人胸部CT的SSDE_(WED)影响较大,且呈0.06倍正线性相关,在临床扫描中精准调节SFOV可以降低成人受检者胸部CT辐射剂量。
