汽车发电机电动势3次谐波分量的估算

分析了Y联接和Y0联接整流电路在畸变电动势作用时的中性点电压,给出了畸变电动势3次谐波分量的估算方法,并估算了Y0联接汽车交流发电机在中性点二极管导通时电动势中3次谐波分量的大小.     

接通“无过渡过程”的三相可控硅开关

本文从理论上探讨了利用可控硅开关实现三相有感电路“无过渡过程”接通的可能性、条件和最佳方案。指出三相零电压开关在纯阻性电路中应用,是它的一种特殊形式。在此基础上,提出了一种在三相有感电路中实现“无过渡过程”接通的可控硅开关的具体电路,实验结果表明如所予期,接通过程三相电流谐波成分很小。     

116MW循环流化床锅炉房的电气优化设计

随着城镇供热的迅速发展,116MW循环流化床锅炉被普遍应用。本文从工程应用和规程规范出发,对116MW循环流化床锅炉房电气设计提出了优化设计方案。     

高压变频器的选用

电力行业及集中供热行业中,锅炉辅机、汽机辅机等大部分大容量电动机均为风机、泵类,如锅炉给水泵、送风机、引风机、循环水泵、凝结水泵等。因此,如何针对不同容量的电动机,正确选用变频器就显得尤为重要。     

新型低压绝缘分裂导线供电模式的实施与展望

针对目前低压电网普遍存在的电能损耗偏高、电压质量差及窃电严重等问题,研制一种新型低压绝缘分裂导线,并基于该导线结构特点提出了供电新模式。示范区二年多的实施结果表明,其经济社会效益显著,对减轻农民电费负担、节支增效有重要的实际意义。     

Quantitative Structure–Activity Relationships of DDT-Type Compounds in a Sodium Tail-Current in Crayfish Giant Axons

Effects of DDT-type compounds including 1,1-bis(para-substituted phenyl)-2,2-dichlorocyclopropanes (DCC-series compounds) on sodium currents in crayfish giant axons were measured under voltage-clamp conditions. Variations in the activity to prolong the tail-current that was observed upon step repolarization of the membrane were quantitatively analysed by use of physicochemical parameters of aromatic substituents and regression analysis. Introduction of lengthy and narrow substituents was favourable to the activity. Variations in the activity were parabolically related to the hydrophobicity, optimum value being around that of H. DDT- and prolan-series compounds were 2–3 times more active than DCC-series compounds when other structural factors were the same. Insecticidal activity of the compounds was linearly correlated with the tail-current activity when the hydrophobic factor was separately considered. The insecticidal activity of DDT-series compounds was 2·5 times higher than that of others when the other factors were the same. © 1997 SCI.     

低压静电场保鲜技术研究进展

随着保鲜技术的日益发展,低压静电场作为一种新兴保鲜技术,得到广泛关注。低压静电场可以通过降低组织中水分含量及酶的活性抑制微生物生长,从而达到延长贮藏期、维持食品原有口感的目的。从低压静电场的保鲜机理、特点、应用及其存在问题进行了阐述,并对该项技术的发展进行了展望。