Christopher J Crowley,Iosif I Shinder,Michael R Moldover et al.
Christopher J Crowley et al.
Laser Doppler anemometers (LDAs) use scattered light to determine velocity components of a flowing fluid. The operating principal of LDAs is simple conceptually; however, it is impractical to trace the LDA-determined velocities to the SI by...
Jared H Strait,Richard A Allen
Jared H Strait
We present an optical scheme to simultaneously characterize the cross-axis and rotational parasitic motions of a long-stroke shaker. By leveraging the geometric properties of a corner cube retroreflector mounted on the shaker load table, we...
Practical realization of the watt from Planck's constant using radiation pressure [0.03%]
基于普朗克常数利用辐射压力实现瓦特的实际化
Brian J Simonds,Kyle A Rogers,Sven Schulze et al.
Brian J Simonds et al.
A primary force standard is implemented to realize the watt through Planck's constant by means of radiation pressure at the kilowatt level. The high amplification laser-pressure optic, or HALO, is a multiple reflection radiation pressure ap...
Patrick F Egan
Patrick F Egan
Upgrades to the vacuum wavelength calibration service at the National Institute of Standards and Technology are reported. The instrumentation centerpiece is an optical frequency comb stabilized to a GPS-disciplined oscillator, thereby provi...
A digital four-arm bridge for the comparison of resistance with capacitance [0.03%]
一种用于电阻和电容对比的四臂桥数字电路
Yicheng Wang,Stephan Schlamminger
Yicheng Wang
We have built and demonstrated a digital four-arm bridge for the comparison of resistance with capacitance. The digital four-arm bridge mimics the classical quad bridge in the digital domain with three balances: the source balance, the dete...
Conversion of a piston-cylinder dimensional dataset to the effective area of a mechanical pressure generator [0.03%]
活塞缸尺寸数据集向机械压力生成器的有效面积的转换
Patrick F Egan,Eric S Stanfield,John R Stoup et al.
Patrick F Egan et al.
Recent developments in diameter metrology at NIST have improved the dimensional characterization of piston-cylinder assemblies (PCAs) to unprecedented precision. For the newest generation of PCAs, the standard uncertainty in the measurement...
T E Parker,R C Brown,J A Sherman
T E Parker
Residual time delays in time transfer systems such as two-way satellite time and frequency transfer (TWSTFT), or GPS carrier phase (GPSCP) change over time. A double difference such as TWSTFT-GPSCP provides information on the changes in the...
K J Kim,A Kim,C S Kim et al.
K J Kim et al.
Unit one is intrusive [0.03%]
第一单元是侵入式的
David Flater
David Flater
The SI brochure's treatment of quantities that it regards as dimensionless, with the associated unit one, requires certain physical quantities to be regarded as simply numbers. The resulting formal system erases the nature of these quantiti...
Improving two-way satellite time and frequency transfer with redundant links for UTC generation [0.03%]
具有备用链路的基于两向卫星的时间和频率传递用于UTC生成中的应用性能提升
Zhiheng Jiang,Victor Zhang,Thomas E Parker et al.
Zhiheng Jiang et al.
Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). At present, more than 12 timing laboratories around the world use SAtellite Time and Ranging Equipment (SA...