Over the past few years, several new achievements have been made from stem cell studies, many of which have moved up from preclinical stages to early, or from early to middle or late, stages thanks to relatively safe ...Over the past few years, several new achievements have been made from stem cell studies, many of which have moved up from preclinical stages to early, or from early to middle or late, stages thanks to relatively safe profile and preliminary evidence of effectiveness. Moreover, some stem cell-based products have been approved for marketing by different national regulatory authorities. However, many critical issues associated mainly with incomplete understanding of stem cell biology and the relevant risk factors, and lack of effective regulations still exist and need to be urgently addressed, especially in countries where establishment of appropriate regulatory system just commenced. More relevantly, the stem cell regulatory sciences need to be established or improved to more effectively evaluate quality, safety and efficacy of stem cell products, and for building up the appropriate regulatory framework. In this review, we summarize some new achievements in stem cell studies, especially the preclinical and clinical studies, the existing regulations, and the associated challenges, and we then propose some considerations for improving stem cell regulatory sciences with a goal of promoting the steadfast growth of the well-regulated stem cell therapies abreast of evolvement of stem cell sciences and technologies.展开更多
根据UPFC系统中串联耦合变压器的功能,分析了其特殊的工作方式和特点,并给出了220 k V输电线路中串联耦合变压器的一种壳式结构方案。根据串联耦合变压器铁芯和绕组的空间几何结构,采用电路与磁路的对偶原理,将磁路模型转化为电路模型...根据UPFC系统中串联耦合变压器的功能,分析了其特殊的工作方式和特点,并给出了220 k V输电线路中串联耦合变压器的一种壳式结构方案。根据串联耦合变压器铁芯和绕组的空间几何结构,采用电路与磁路的对偶原理,将磁路模型转化为电路模型。考虑到硅钢片的非线性饱和特性,采用复数磁导率计及涡流效应,以非线性电感和电阻来等效硅钢片,分析了频率和磁导率对硅钢片等效参数的影响。基于磁路法提取漏感参数,建立了串联耦合变压器的仿真电路模型。在低压物理样机上进行空载合闸和三相不对称直流偏磁的试验与仿真计算,测量结果与计算结果基本吻合,表明了所建模型适用于串联耦合变压器暂态模拟与不对称直流偏磁特性的分析。展开更多
文摘Over the past few years, several new achievements have been made from stem cell studies, many of which have moved up from preclinical stages to early, or from early to middle or late, stages thanks to relatively safe profile and preliminary evidence of effectiveness. Moreover, some stem cell-based products have been approved for marketing by different national regulatory authorities. However, many critical issues associated mainly with incomplete understanding of stem cell biology and the relevant risk factors, and lack of effective regulations still exist and need to be urgently addressed, especially in countries where establishment of appropriate regulatory system just commenced. More relevantly, the stem cell regulatory sciences need to be established or improved to more effectively evaluate quality, safety and efficacy of stem cell products, and for building up the appropriate regulatory framework. In this review, we summarize some new achievements in stem cell studies, especially the preclinical and clinical studies, the existing regulations, and the associated challenges, and we then propose some considerations for improving stem cell regulatory sciences with a goal of promoting the steadfast growth of the well-regulated stem cell therapies abreast of evolvement of stem cell sciences and technologies.
文摘根据UPFC系统中串联耦合变压器的功能,分析了其特殊的工作方式和特点,并给出了220 k V输电线路中串联耦合变压器的一种壳式结构方案。根据串联耦合变压器铁芯和绕组的空间几何结构,采用电路与磁路的对偶原理,将磁路模型转化为电路模型。考虑到硅钢片的非线性饱和特性,采用复数磁导率计及涡流效应,以非线性电感和电阻来等效硅钢片,分析了频率和磁导率对硅钢片等效参数的影响。基于磁路法提取漏感参数,建立了串联耦合变压器的仿真电路模型。在低压物理样机上进行空载合闸和三相不对称直流偏磁的试验与仿真计算,测量结果与计算结果基本吻合,表明了所建模型适用于串联耦合变压器暂态模拟与不对称直流偏磁特性的分析。
