共查询到20条相似文献,搜索用时 10 毫秒
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以聚偏氟乙烯(PVDF)为基体,经与炭黑等混合后挤出成型辐照。研究了两种不同类型导电炭黑(CB)对复合物导电性和正电阻温度系数(PTC)的影响,辐射剂量对PTC性能的影响,以及HDPE/PVDF配比对复合物PTC性能的影响。通过CB在HDPE/PVDF中配比不同时分布的扫描电镜(SEM)观测,随着PVDF含量的增加,C... 相似文献
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The results of an investigation of the effect of temperature drift of the lamp base on the brightness temperature produced by a tungsten filament lamp are presented. The dependence of the temperature coefficient of gas-filled and vacuum lamps on the brightness temperature is determined. The error in the calibration characteristic of the lamp, connected with the temperature instability of the lamp base with time, is estimated. 相似文献
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低温超音速火焰喷涂特性研究 总被引:1,自引:1,他引:1
由于冷喷涂技术的工作气压过高,限制了其应用.为此,应用多功能超音速火焰喷涂系统(KY-HVO/AF)焰流温度调节范围大的特点,设计了液料送粉系统和控制装置,扩大了喷涂低温工作范围,达到了低温喷涂工作温度和速度,实现了低温喷涂.采用压入式气液动力转换提供送粉动力,控制装置采用槽孔式计量方式,实现对流量的量化控制,整个数字化系统控制简单、可靠.以数值模拟的方式,分析了HVAF喷涂工作状态,液料流量、空气流量、煤油流量对焰流工作状态的影响,着重研究了不同液料流量时焰流状态的变化规律.结果表明,空气流量、煤油流量、液料流量是控制喷涂温度的三个重要因素,应用此技术成功地制备了纳米TiO2涂层. 相似文献
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阳极催化剂是低温燃料电池的关键材料之一,研制新型催化剂对燃料电池的性能及成本起着关键作用。从改变催化剂的组成、分散度及调控催化剂的表面结构3个方面综述了近年来低温燃料电池阳极催化剂的研究进展,并展望了该领域今后的发展方向。 相似文献
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This paper determines and compares the temperature coefficient of the standard inductors, manufactured by General Radio, using three different methods. The temperature coefficients have been determined by observing the change in inductance at 1 kHz and change in resistance at 1 kHz and 20 Hz. The standard inductor has been measured using precision LCR meter in a controlled and stable environment. The temperature coefficient is substantial when measured as a function of change in inductance in comparison to change in resistance as suggested by manufacturer. This information may be useful in computing the measurement uncertainty and analyzing the results of International comparisons and proficiency testing programs. 相似文献
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双温双压法低露点标准湿度发生器 总被引:2,自引:0,他引:2
通过采用双温双压法原理 ,研制了一套微量水分发生装置。该装置能发生露点范围为 2 0~ - 74℃D .P的恒定含水量的气体 ,其测试室的变温范围为 2 0~ - 6 0℃ ,变压范围为 10 0~ 10 0 0kPa(绝对压力 ) ,其三倍标准偏差最大不确定度为± 0 .15℃D .P。装置适合于各类露点仪和水分分析仪器的计量校正。本装置中设计制作了能耐受 1MPa压力并且既适用于水面又适用于冰面的叠盘迷宫式饱和器 ,该饱和器由12个内有螺旋式气流通道的不锈钢圆盘组成 ,总的传质通道长度超过 6 0米 ,保证了其在低温和压力条件下的饱和度接近 10 0 %。 相似文献
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采用高能球磨分散方法制备了稳定的聚合物多元醇/碳纳米管分散液,并通过原位聚合制备了导电聚氨酯(PU)/碳纳米管(CNTs)硬质泡沫复合材料。采用扫描电镜(SEM)表征了泡沫复合材料的结构,研究了CNTs含量对泡沫材料导电性的影响以及泡沫材料的负温度系数(NTC)效应,通过压缩测试考察了泡沫材料的力学性能。结果表明,CN... 相似文献
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采用双温双压法原理研制了一套宽温度范围、测试室压力可变的标准湿度发生器。它能够测量发生温度范围为-50~90 ℃、相对压力范围为-50~0 kPa、扩展不确定度为0.3%RH~0.8%RH(k=2)的5%RH~96%RH全量程相对湿度。其测试室尺寸为150 mm×400 mm,样气流量为5~30 L/Min。通过设计高精度饱和器压力和流量自动调节装置,采用工控机与PLC相结合的操作控制方式,实现了全自动运行。冷镜式精密露点仪和重量法湿度计的实际测试结果均验证了其不确定度。 相似文献
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V. N. Shut S. P. Syrtsov E. L. Gavrilenko A. V. Gavrilov 《Journal of Engineering Physics and Thermophysics》2005,78(4):728-732
The space-time temperature distribution in materials with a positive temperature coefficient of resistance under the action
of electric current on them has been analyzed by numerical methods. The nonstationary boundary-value heat-conduction problem
with a nonlinearity of the third kind has been solved. The results obtained theoretically have been compared to experimental
data.
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Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 97–101, July–August, 2005. 相似文献
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《IEEE transactions on instrumentation and measurement》1973,22(3):234-239
Equipment is described for comparing any number N of standard cells which constitute a standard of electromotive force. The scheme is economical, needing only 2N measurements. The cells are disposed in a ring, and there is simple switching to compare each cell with its four neighbors. The calculations are done by a program on a desk calculator. They give the value of each cell with respect to the mean of the group. They also give the rms error, which is typically less than 0.02 ?V for one cell in a group of 22. There are safeguards for identifying a spurious measurement and a false keyboard entry. 相似文献