Experimental study of the long-gap distance vacuum arc distortion for three types of axial magnetic field （AMF） contacts, by using high-speed charge coupled device （CCD）, is presented. The arc current was of a hal...Experimental study of the long-gap distance vacuum arc distortion for three types of axial magnetic field （AMF） contacts, by using high-speed charge coupled device （CCD）, is presented. The arc current was of a half-cycle sine wave with a frequency of 50 Hz, produced by an L=C discharging circuit. The time of appearance and duration of vacuum arc distortion under three conditions were studied. It was found that the gap distance, current and diameter of the electrode affected the characteristics of vacuum distortion at a long-gap distance. Some characteristics of the vacuum arc at a long-gap distance were revealed and the experience and data for further investigation were provided.展开更多
BACKGROUND Esophageal replacement(ER)with gastric pull-up(GPU)or jejunal interposition(JI)used to be the standard treatment for long-gap esophageal atresia(LGEA).Changes of the ER grafts on a macro-and microscopic lev...BACKGROUND Esophageal replacement(ER)with gastric pull-up(GPU)or jejunal interposition(JI)used to be the standard treatment for long-gap esophageal atresia(LGEA).Changes of the ER grafts on a macro-and microscopic level however,are unknown.AIM To evaluate long-term clinical symptoms and anatomical and mucosal changes in adolescents and adults after ER for LGEA.METHODS A cohort study was conducted including all LGEA patients≥16 years who had undergone GPU or JI between 1985-2003 at two tertiary referral centers in the Netherlands.Patients underwent clinical assessment,contrast study and endoscopy with biopsy.Data was collected prospectively.Group differences between JI and GPU patients,and associations between different outcome measures were assessed using the Fisher’s exact test for bivariate variables and the Mann-Whitney U-test for continuous variables.Differences with a P-value<0.05 were considered statistically significant.RESULTS Nine GPU patients and eleven JI patients were included.Median age at follow-up was 21.5 years and 24.4 years,respectively.Reflux was reported in six GPU patients(67%)vs four JI patients(36%)(P=0.37).Dysphagia symptoms were reported in 64%of JI patients,compared to 22%of GPU patients(P=0.09).Contrast studies showed dilatation of the jejunal graft in six patients(55%)and graft lengthening in four of these six patients.Endoscopy revealed columnar-lined esophagus in three GPU patients(33%)and intestinal metaplasia was histologically confirmed in two patients(22%).No association was found between reflux symptoms and macroscopic anomalies or intestinal metaplasia.Three GPU patients(33%)experienced severe feeding problems vs none in the JI group.The median body mass index of JI patients was 20.9 kg/m^(2) vs 19.5 kg/m^(2) in GPU patients(P=0.08).CONCLUSION The majority of GPU patients had reflux and intestinal metaplasia in 22%.The majority of JI patients had dysphagia and a dilated graft.Follow-up after ER for LGEA is essential.展开更多
采用Halbach单侧聚磁特性,设计出了一种大气隙外笼型转子磁力耦合器(Long Air Gap External-cage Rotor Magnetic Coupler,LAEMC),并分析了其运行特性、调速特性及散热特性,推导出LAEMC电磁转矩解析表达式,据此分析了结构参数对电磁转...采用Halbach单侧聚磁特性,设计出了一种大气隙外笼型转子磁力耦合器(Long Air Gap External-cage Rotor Magnetic Coupler,LAEMC),并分析了其运行特性、调速特性及散热特性,推导出LAEMC电磁转矩解析表达式,据此分析了结构参数对电磁转矩的影响,得出了不同磁化比的Halbach结构对LAEMC电磁转矩的影响规律;根据LAEMC的运行特性,分析了其在离心式负载、恒功率负载及恒转矩负载的调速特性,表明其仅适合离心式负载调速并具有良好的节能效果;在离心式负载转差率为33%处的最大功率损耗点对LAEMC进行热仿真计算,得到永磁体工作温度约为60℃,而通过气隙与之相隔的笼条温度约为360℃,两者温度差达300℃以上,表明所提出的大气隙外笼型转子磁力耦合器———LAEMC在离心式负载上既具有良好的运行特性也具有良好的隔热效果。展开更多
基金supported by National Natural Science Foundation of China (No.50477024)
文摘Experimental study of the long-gap distance vacuum arc distortion for three types of axial magnetic field （AMF） contacts, by using high-speed charge coupled device （CCD）, is presented. The arc current was of a half-cycle sine wave with a frequency of 50 Hz, produced by an L=C discharging circuit. The time of appearance and duration of vacuum arc distortion under three conditions were studied. It was found that the gap distance, current and diameter of the electrode affected the characteristics of vacuum distortion at a long-gap distance. Some characteristics of the vacuum arc at a long-gap distance were revealed and the experience and data for further investigation were provided.
文摘BACKGROUND Esophageal replacement(ER)with gastric pull-up(GPU)or jejunal interposition(JI)used to be the standard treatment for long-gap esophageal atresia(LGEA).Changes of the ER grafts on a macro-and microscopic level however,are unknown.AIM To evaluate long-term clinical symptoms and anatomical and mucosal changes in adolescents and adults after ER for LGEA.METHODS A cohort study was conducted including all LGEA patients≥16 years who had undergone GPU or JI between 1985-2003 at two tertiary referral centers in the Netherlands.Patients underwent clinical assessment,contrast study and endoscopy with biopsy.Data was collected prospectively.Group differences between JI and GPU patients,and associations between different outcome measures were assessed using the Fisher’s exact test for bivariate variables and the Mann-Whitney U-test for continuous variables.Differences with a P-value<0.05 were considered statistically significant.RESULTS Nine GPU patients and eleven JI patients were included.Median age at follow-up was 21.5 years and 24.4 years,respectively.Reflux was reported in six GPU patients(67%)vs four JI patients(36%)(P=0.37).Dysphagia symptoms were reported in 64%of JI patients,compared to 22%of GPU patients(P=0.09).Contrast studies showed dilatation of the jejunal graft in six patients(55%)and graft lengthening in four of these six patients.Endoscopy revealed columnar-lined esophagus in three GPU patients(33%)and intestinal metaplasia was histologically confirmed in two patients(22%).No association was found between reflux symptoms and macroscopic anomalies or intestinal metaplasia.Three GPU patients(33%)experienced severe feeding problems vs none in the JI group.The median body mass index of JI patients was 20.9 kg/m^(2) vs 19.5 kg/m^(2) in GPU patients(P=0.08).CONCLUSION The majority of GPU patients had reflux and intestinal metaplasia in 22%.The majority of JI patients had dysphagia and a dilated graft.Follow-up after ER for LGEA is essential.
文摘采用Halbach单侧聚磁特性,设计出了一种大气隙外笼型转子磁力耦合器(Long Air Gap External-cage Rotor Magnetic Coupler,LAEMC),并分析了其运行特性、调速特性及散热特性,推导出LAEMC电磁转矩解析表达式,据此分析了结构参数对电磁转矩的影响,得出了不同磁化比的Halbach结构对LAEMC电磁转矩的影响规律;根据LAEMC的运行特性,分析了其在离心式负载、恒功率负载及恒转矩负载的调速特性,表明其仅适合离心式负载调速并具有良好的节能效果;在离心式负载转差率为33%处的最大功率损耗点对LAEMC进行热仿真计算,得到永磁体工作温度约为60℃,而通过气隙与之相隔的笼条温度约为360℃,两者温度差达300℃以上,表明所提出的大气隙外笼型转子磁力耦合器———LAEMC在离心式负载上既具有良好的运行特性也具有良好的隔热效果。
