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1.
乳状液电磁场破乳法的研究 总被引:5,自引:0,他引:5
提出了一种利用电磁感应原理产生涡旋电场进行破乳的新方法。将螺线管、磁芯构成的电感器与电容器串联组成L-C谐振电路。在此电路中通过高频电流,使其在破乳器内产生高频磁场,从而感生出高频涡旋电场。在此电场的作用下,乳状液滴极化并加速其运动与碰撞,达到破乳的目的。该法在输入信号电压约300V、电流几+mA、频率20kHz的条件下,可感应出强度为几十+kV/cm的涡旋电场,5min内静态破乳率大于98%。在 相似文献
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In an effort to test the empirical law governing the scaled superheat-limit,1 we measured superheated neon and hydrogen with special emphasis on the critical superheat. Experimental results were compared with a Döring-Zeldovich-like nucleation theory and satisfactory agreement was found. Some deviation from the corresponding states of the scaled superheat-limit for classical fluids was apparent, thought to be caused by quantum effects on surface tension, and are appreciable for neon and hydrogen. 相似文献
3.
Effect of an applied electric field on the oxidation rate of vacuum deposited aluminium thin films were studied at room temperature
in the laboratory atmosphere. Above the critical field, a negative potential applied to the film enhanced the rate of oxidation,
while a positive field retarded the rate. This suggests an oxidation mechanism involving cationic diffusion. The observed
change in the rate of oxidation for an applied field agrees with the Mott-Cabrera theory. 相似文献
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碳纳米管冷阴极超高真空鞍场规的电场模拟与实验研究 总被引:1,自引:0,他引:1
在静电鞍场规的基础上研制了一种碳纳米管(CNT)冷阴极鞍场规(SFG).这种冷阴极鞍场规具有电极尺寸小,吸放气率低,热效应低,功耗低的特点.本文首先计算了碳纳米管冷阴极鞍场规的电场分布,计算结果表明,二极型碳纳米管电子枪的引出栅极的正电位在低于100 V的情况下对环形阳极鞍场规的轴向电位分布影响很少;并且在现有条件下对规管参数进行了测试,实验测定的规管对空气的灵敏度是1.05 Pa-1,规管功耗由热阴极规的0.9瓦减小到7毫瓦. 相似文献
7.
Interfaces between metals and polytetrafluoroethylene (TFE) are common in cryogenic systems. In this paper we present results from measurements of the temperature dependence of the dynamic coefficient of friction between commercially pure copper and TFE. The effect of the copper surface finish was also determined. The effects of load and speed were evaluated over a small range, but nearly all data were taken at a surface speed of 5.4 cm s?1 with a load of 1.63 N cm?2. These values are typical of those encountered by the moving parts of some cryogenic machinery. 相似文献
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The characteristics of four commercial strain-gauge pressure transducers suitable for measurements in a temperature range from 4.2 to 293 K were determined in the presence of magnetic fields up to 6 T. The highest pressure measured was 3.5 MPa. Tests showed that if the transducers are used in these conditions and no corrections are made, uncertainties up to 19% of the transducer full scale may be inherent in measurements. When such high error levels are unacceptable, the transducers must be individually calibrated under the working conditions: in this way the uncertainties in pressure measurements can usually be kept below 1 % of the transducer full scale. 相似文献
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在低温贮罐内贮存液氢、液氧、液氮,液住的精确测量是非常重要的。本文介绍了差压式液位测量方法,经实践应用证明,其结果是比较令人满意的。 相似文献
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By applying square wave AC voltage to the Au source electrode of tetracene based field-effect transistor (FET), electroluminescence (EL) was obtained. The results suggest that electrons and holes were injected alternately from the source electrode and recombined each other, and lead to the EL. This type of EL was localized at the interface between the source electrode and tetracene, and enhanced periodically with two relaxation times in accordance with the applied AC voltage cycle. We modeled the carrier behavior in the FET and explained the decay of EL, taking into account the space charge field contribution. Finally, using an AC voltage superposed on DC bias voltage, it was shown that electron injection was prompted only by space charge field. 相似文献
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F. Schauer 《低温学》1984,24(2):90-96
The cryogenic high voltage bushing for the terminations of the 138 kV, 4100 A superconducting cable prototype at the Brookhaven National Laboratory (BNL) is described. The bushing is energized with the line-to-ground voltage between the coaxial centre and outer surrounding conductors, in the axial direction there is a temperature difference from ambient to about 6 K.The capacitively graded bushing can be mounted in any position. It is vacuum tight and withstands pressures of more than 20 bar. The heat leak of the insulation body in axial direction is only 8.5 W.The electrical specifications of the bushing are: 825 kV, 1.2 × 50 μs impulse voltage; 240 kV rms ac 2h test voltage: and > 160 kVs partial discharge inception voltage.This bushing concept may easily be modified to meet most conceivable thermal, mechanical and electrical requirements of cryogenic high voltage engineering. 相似文献
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The critical temperature has been measured for various magnet conductors as a function of the perpendicular applied magnetic field. The isothermal environment was provided by a variable temperature cryostat which fits into the bore of a 10 telsa solenoid. The temperature gradient across the sample volume was measured to be less than 25 millikelvins. The superconducting to normal state transition was measured resistively, using sample current densities from 0.01 to 2 A cm?2. The maximum applied magnetic field was 10 T and varied less than 0.5% in the sample volume. The critical transport current range of the samples measured from tens to thousands of amperes in the presence of a 10 T perpendicular magnetic field at 4.2 K. 相似文献
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针对目前国内还没有在环境监测中广泛使用的对工频电场探头进行计量的检定规程或者校准规范,设计了一套工频电场探头校准装置,根据理论推导,确定所产生标准电场强度。通过高压源控制器来控制升压实现高压输出。校准所采用的电板满足所有工频电场测量仪校准需求,产生的电场强度范围从10 V/m到100 kV/m。最后,对溯源后的HI-3604分别进行电场强度测试与分析,实验数据表明:该校准装置可以用于工频电场探头校准,并给出了校准不确定度。 相似文献
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Equipment and procedures for long-term cryogenic creep testing are presented in detail. Particular attention was given to the maintaining of constant cryogenic test temperature and with respect to the stability and sensitivity of strain measurements. Typical long-term cryogenic creep testing results on oxygen free high conductivity (OFHC) copper are presented. 相似文献
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The long-term creep behaviour of OFHC copper was investigated at 4.2 K and 77 K. At 77 K, steady-state creep was observed and the creep rates were tens of orders of magnitude higher than would be expected from extrapolations of ambient temperature creep data. The stress exponent obtained at 77 K is 2.2. The apparent activation energy at 77–90 K range is about 0.02 eV. At 4.2 K, transient creep was observed. TEM study of all crept specimens showed cell structures in support of the occurrence of substantial creep at cryogenic temperatures. 相似文献
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A.L. Johnson 《低温学》1983,23(7):339-347
The status of cryogenic refrigerator development intended for, or possibly applicable to, long life spacecraft borne application is reviewed. Based on these efforts, the general development trends are identified. Using currently projected technology needs, the various trends are compared and evaluated. The linear drive, non-contacting bearing Stirling cycle refrigerator concept appears to be the best current approach that will meet the technology projection requirements for spacecraft borne cryogenic refrigerators. However, a multiple redundant set of lightweight, moderate life, moderate reliability Stirling cycle cryogenic refrigerators using high-speed linear drive and sliding contact bearings may possibly suffice. 相似文献
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