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11.
论开发750 kV超高压真空断路器的必要性 总被引:7,自引:0,他引:7
简述了真空断路器的发展概况,对真空断路器与SF6断路器进行了对比分析。同时对真空断路器向750kV超高压等级发展的途径进行论述。 相似文献
12.
13.
Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100)
and Si(111) vs. Si(111) interfaces, obtained in
Torr and in 0.2 Torr partial pressure of hydrogen gas (
) from room temperature to 850°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology
described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within
a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular
hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of
a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular
hydrogen. The
also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level
of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire
range of standard thermal ramping in both atmospheric environments is in the extremely high 10-12m3/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude
reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous
findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings
and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen
at surface temperatures between 100 and 300°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
根据多次真空展的统计数据,总结出第10届国际真空展的四大亮点:参展厂商数及参展外商数、展位数均创历史新高;干泵成展会主角;流通、服务业方兴未艾,国内参展厂商高端产品比重增加.通过参展,作者认为:应从新能源开发,在新一轮产业革命中寻求真空行业发展的新机遇. 相似文献
15.
Commercial-scale experiments carried out during the last five years have shown that the cooling time of a head of lettuce, wrapped in PVC film and packed in a carton, can vary from 25 to 65 min, depending on the design of the vacuum installation. Experiments were, therefore, carried out with a commercial four pallet vacuum cooler, provided in accordance with the requirements of the Agricultural Engineering Institute, with three vacuum pumps and two compressors. The influence of pumping speed, cooling unit capacity and initial temperature on the cooling time and on the final temperature of lettuce leaves and butts was investigated. The results were compared with the cooling rate obtained with other vacuum cooling installations. Design data are proposed. 相似文献
16.
The volatilization behavior of Cu, Pb, Sn, Sb, Ni, Zn, Mn, Co, Cr, Cd during pyrolysis of waste printed circuit boards was investigated in a bench-scale fixed-bed pyrolysis system. It was found that volatility of heavy metals increases with operating temperature elevating, and bromine and vacuum have an obvious promoting effect on volatility of most of heavy metals. Over 99% weight of Cu and Ni are still remained in solid residue after pyrolysis, about 20% weight of Sb, Zn and Cd are transfered into liquid and gas during a pyrolysis process at 600 ℃, volatilization fractions of Pb, Sn, Mn, Co, Cr are less than 10% at the same conditions. The contents of heavy metals in liquid and gas products depend on not only volatility of metals, but also their initial contents in printed circuit boards, pyrolysis liquid and gas are primarily contaminated by Cu, Pb, Sn, Sb and Zn, their contents in liquid vary from 10^2 to 10^3 pg/mL, Mn, Co, Cr, Cd were detected only at very low level, less than 10 μg/mL. 相似文献
17.
为了改进传统真空预压法的缺陷,提出一种PHD-PVD真空预压联合电渗处治工程废浆的方法。通过6组大型室内模型试验,对工程废浆固结过程中的排水量、电流强度、沉降值等进行监测,通过测量土体含水率及十字板抗剪强度并结合压汞试验宏微观分析土体的加固效果,研究真空泵和电源的间歇断开处理对PHD-PVD真空预压联合电渗法加固工程废浆效果的影响。试验结果表明,联合电渗法有效提升了PHD-PVD真空预压法后期的排水效率,远端土体固结程度得到提高,强度显著提升;对真空泵和电源的间歇断开式处理使土中产生新的排水通道,一定程度上缓解了排水板附近的淤堵,使得试验后期也保持了较快的排水速率,排水总量得到提升。压汞试验结果表明,采用间歇断开式的PHD-PVD真空预压联合电渗法处理的工程废浆,其峰值孔径更小,土体微观结构更加致密。 相似文献
18.
主要介绍了高温粘接技术在铁氧体环真空溅射加工中的应用,通过对耐高温胶粘剂的优选及工艺实现途径的探索,较好地将多个铁氧体环粘接为一体。并在其外表面溅射镀铜,粘接强度及粘接精度在高温环境下均达到设计要求。 相似文献
19.
20.
M. Sh. El-Gayar A. E.-M. Ahmed G. A. Gohar A. H. Hegazi H. M. Ibrahim A. M. Aly 《Petroleum Science and Technology》2013,31(14):1434-1444
Abstract Vacuum distillates of an Egyptian crude oil were subjected to solvent extraction process applying N-methyl-2-pyrrolidone (NMP) and furfural as dearomatization solvents. The study shows that the extraction solvent together with the temperature and solvent-to-oil ratio have a significant effect on the yield and quality of produced lubricating oils. The optimum temperature for extracting light waxy distillates with NMP is 55°C at the solvent-to-feed ratio 2:1. These conditions are appropriate to remove the major portion of aromatics from the raffinate. The apparent activation energy (Ea), enthalpy (ΔH*), entropy (ΔS*), and free energy of activation (ΔG*) were calculated for the solvent dearomatization process. 相似文献