共查询到17条相似文献,搜索用时 281 毫秒
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介绍了项目"1mN·m~1N·m扭矩国家基准装置的建立"的立项背景、基本情况和项目取得的成果及主要创新。该项目采用了多项自主研发的关键技术,成功研制了国内首台基于空气轴承支撑技术的全自动高准确度微小扭矩标准装置,该装置复现的扭矩值范围为1mN·m~1N·m,扭矩值不确定度(k=2)在100mN·m~1N·m范围内小于5×10~(-5);在5mN·m~100mN·m范围内小于1×10~(-4);在1mN·m~5mN·m内小于5×10~(-4)。 相似文献
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中国一级标准海水作为有证标准物质,不确定度是其一项重要的质量参考指标。参考了国际标准海水(IAPSO SSW)不确定度的分析方法,引入GB/T 15000.3《标准样品工作导则(3)-标准样品定值的一般原则和统计方法》等标准中相关的统计方法,对定值不确定度、均匀性不确定度、长期稳定性不确定度3个分量进行了逐一分析。以P1批次一级标准海水的数据为例,计算得出以上分量的电导率比不确定度分别为5.00×10-6、 5.05×10-6、 4.50×10-6,合成标准不确定度为8.42×10-6,扩展不确定度为1.7×10-5。依据不确定度传播规律,计算得出盐度扩展不确定度为6.6×10-4(或0.001)。 相似文献
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介绍了基于光腔衰荡光谱法测定气体中的微量水的方法原理,该方法适用于含量为0.2×10-9~20×10-6 mol/mol的所有气体中水分的测定。建立了光谱分析法的原始数学模型,对测定方法的不确定度进行了评估,结果表明该方法的扩展不确定度为(8~20)×10-9 mol/mol(k=2,p=95%)。 相似文献
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对机械合金化(MA)法制备的TiC/Ti复合涂层进行电子束重熔处理,分析了经过不同电子束扫描速度的重熔工艺后TiC/Ti复合涂层组织和耐磨性能的变化规律。结果表明,当扫描速度为5~15 mm/s时,重熔处理消除了MA法制备的TiC/Ti复合涂层中的孔隙和裂纹,使其硬度与耐磨性能显著提高;但扫描速度过快(20 mm/s)时,TiC/Ti复合涂层内部出现重熔导致的孔洞缺陷。随着扫描速度由5 mm/s增加至15 mm/s,重熔后TiC/Ti复合涂层中的TiC相由粗大树枝状晶体逐渐转变为弥散分布的短棒和颗粒状晶体,弥散强化作用和固溶强化作用逐渐增强,TiC/Ti复合涂层的硬度由重熔前HV 554逐渐提高至HV 783,磨损速率由5.93×10-4 mm3(N·m)-1逐渐下降至1.75×10-4 mm3(N·m)-1,扫描速度为15 mm/s重熔后TiC/Ti复合涂层的性能最佳。 相似文献
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利用六钛酸钾晶须(K2O·6TiO2)对苯并噁嗪(BOZ)树脂及玻璃纤维/苯并噁嗪(GF/BOZ)复合材料的摩擦磨损性能进行改性,分析了K2O·6TiO2/BOZ复合材料以及K2O·6TiO2-GF/BOZ混杂复合材料的摩擦磨损性能以及改性机理。结果表明:因K2O·6TiO2的加入,K2O·6TiO2/BOZ复合材料以及K2O·6TiO2-GF/BOZ混杂复合材料的摩擦系数和比磨损率较纯BOZ树脂和GF/BOZ复合材料的明显降低。K2O·6TiO2显著减轻了BOZ树脂和GF/BOZ复合材料的摩擦粘着状况,使摩擦系数降低,同时磨粒磨损情况也大为减轻。GF/BOZ复合材料在摩擦过程中摩擦应力通过率先破坏GF和BOZ树脂的界面,进而诱发破坏GF束内、GF束间和层间BOZ树脂,使得GF/BOZ复合材料的摩擦系数比BOZ树脂降低,但比磨损率较BOZ树脂升高,而K2O·6TiO2的加入,使K2O·6TiO2-GF/BOZ混杂复合材料的比磨损率有效降低。BOZ树脂、GF/BOZ、K2O·6TiO2-GF/BOZ 3种材料的摩擦系数和比磨损率分别为0.34和0.66×10-6 mm3·(N·m)-1,0.19和1.2×10-6 mm3·(N·m)-1,0.09和0.69×10-6 mm3·(N·m)-1。 相似文献
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Popel R. Niemeyer J. Grimm L. Dunschede F. Meier W. 《IEEE transactions on instrumentation and measurement》1991,40(5):805-810
Two Josephson voltage standards have been compared using a room-temperature electronic nanovoltmeter with a peak-to-peak noise of about 2 nV at the 1-V level corresponding to a RMS uncertainty of 4×10-10. The excellent stability in maintaining the desired voltage steps makes it possible to obtain recorder traces comparing Nb/Al2O3/Nb Josephson standards with Weston cells and Zener reference standards at 1 V and 10 V. At 10 V the best result shows a peak-to-peak noise of 250 nV corresponding to a RMS uncertainty of 5×10-9 for a Zener reference and 50 nV corresponding to 1×10-9 for a series connection of nine Weston cells. As an example for the application of the Josephson standard as a potentiometer the deviation in the linearity of a digital voltmeter is confirmed to be on the order of 0.1 p.p.m. in the range from -10 V to +10 V 相似文献
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Shifrin V.Y. Po Gyu Park Khorev V.N. Chang Ho Choi Sekyung Lee 《IEEE transactions on instrumentation and measurement》1999,48(2):196-199
Tesla-to-ampere ratio giving the largest error in the γ'P-low-field-experiment has been determined using a modified noncontacting method. The total uncertainty of 0.164×10 -6 has been attained. The constant of a solenoid and the γ'P-value have been corrected for magnetic susceptibility of air. The result is γ'P=2.675 154 18×108 s-1 T-1 (Tesla BI-90) with the total uncertainty of 0.18×10-6 相似文献
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A 100000-A, high precision device of the magnetic modulation current comparator type, which can be used in industrial heavy direct current systems for online calibration and measurement, is presented. Testing of the comparator indicates that its current ratio accuracy is 5×10-5, and that measurements of voltage with a standard resistor achieve an accuracy of 5×10-4. These are slightly degraded to 3×10-4 for on-site calibration and 1×10-3 for on-site measurement. The device, which has a toroidal configuration, can be opened for each installation on a busbar, with a variation in accuracy of less than 2×10-5. Its magnetic shielding renders it insensitive to magnetic fields up to 1×10-2 Tea. Its accuracy is better by a factor of two than that of similar industrial measuring devices. The principle of operation and the characteristics of the comparator, the double shielded design, and an analysis of its errors are discussed 相似文献
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Zhang Z. Wang D. Hu Z. Zhen J. He Q. Qiao W. Bliek L. Hein G. Kowalski W. Ebeling K.J. Bruus H. 《IEEE transactions on instrumentation and measurement》1991,40(6):889-892
Equipment for precise measurement of the quantized Hall resistance (QHR) at the National Institute of Metrology (NIM), Beijing, China, is described. The essential parts in this equipment are a resistance comparator of one-to-one ratio with a comparison uncertainty of 3×10-8 and two specially designed resistor networks used for determining of the ratio between 12906.4035 Ω of QHR at i =2 and 10 kΩ or 1 kΩ. The transfer procedure from QHR to 10 kΩ or 1 kΩ can be completed easily with this equipment by a few one-to-one comparisons with a total uncertainty of 5×10-8 相似文献
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An automated guarded resistance bridge has been specifically developed at the National Institute of Standards and Technology (NIST) for the calibration of high-quality 10 kΩ standard resistors. The system is designed to compare up to 30 nominally equal, four-terminal resistors with a resolution and combined relative standard uncertainty of 0.01×10-6 and 0.02×10-6, respectively. It features a self-balancing detector circuit, and a programmable coaxial connector switch for selecting resistors. With a few minor modifications, the system is capable of comparing other nominally equal resistors in the range 100 Ω to 1 MΩ 相似文献