National Metrology Institute of Japan NMIJ

Tsukuba, Japan

National Metrology Institute of Japan NMIJ

Tsukuba, Japan

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Roske D.,Physikalisch - Technische Bundesanstalt | Ogushi K.,National Metrology Institute of Japan NMIJ
Metrologia | Year: 2016

The results of the measurements (deflections and uncertainties) reported by the participants of the CIPM key comparison CCM.T-K2 to the pilot laboratory were evaluated. Some known effects were included into the evaluation by correction terms. In detail, corrections for the deviations of the amplifiers of the participating laboratories, the creep influence due to different loading times in the machines and the environmental conditions on site were calculated. The Annex contains the calculation of the key comparison reference values, the corresponding uncertainties, the relative deviations of the values from the reference value and the degrees of equivalence.


Uchida T.,National Metrology Institute of Japan NMIJ | Takeuchi S.,Toin University of Yokohama | Kikuchi T.,National Metrology Institute of Japan NMIJ
Japanese Journal of Applied Physics | Year: 2012

We have been studying measurement techniques of acoustic cavitation using a cavitation sensor. Cavitation was investigated using broadband integrated voltage (BIV) calculated from broadband noise. In this study, the distribution of BIV in the vertical direction in a water vessel was measured with a novel cavitation sensor with improved spatial resolution. As a result, it was found that the pattern of standing wave acoustic field could be measured with the novel cavitation sensor. Also, the values of BIV measured in the vertical direction agreed well with sonochemical luminescence. The novel sensor has potential as a tool for accurate evaluation using acoustic cavitation in several fields. © 2012 The Japan Society of Applied Physics.


Uchida T.,National Metrology Institute of Japan NMIJ | Takeuchi S.,Toin University of Yokohama | Kikuchi T.,National Metrology Institute of Japan NMIJ
Japanese Journal of Applied Physics | Year: 2011

We have been developing a measurement technique for the amount of generated acoustic cavitation using broadband integrated voltage (BIV), calculated from high-frequency components of broadband noise in the output signal of a cavitation sensor. BIV is a signal caused by the effect of bubbles produced by acoustic cavitation. In this study, one dimension distribution of cavitation generation in a water vessel was measured in terms of BIV and sound pressure. The results show that the peak positions of BIV and sound pressure were different. Although the sound pressure was high at the center position generating the flow toward the surface of water, BIV was low because no cavitation bubbles were trapped. Hence, BIV has potential use in the measurement of the spatial distribution of cavitation generation more accurately than sound pressure. © 2011 The Japan Society of Applied Physics.


Taguchi T.,Osaka Seimitsu Kikai Co. | Kondo Y.,National Metrology Institute of Japan NMIJ
Measurement Science and Technology | Year: 2016

High-precision gears are required for advanced motion and power transmission. The reliability of the measured value becomes important as the gear accuracy increases, and the establishment of a traceability system is needed. Therefore, a high-precision gear measuring machine (GMM) with a smaller uncertainty is expected to improve the gear calibration uncertainty. For this purpose, we developed a prototype of a high-precision GMM that adopts a direct drive mechanism and other features. Then, the high measurement capability of the developed GMM was verified using gear artifacts. Recently, some new measurement methods using simple shapes such as spheres and planes have been proposed as standards. We have verified the tooth profile measurement using a sphere artifact and reported the results that the developed GMM had a high capability in tooth profile measurement. Therefore, we attempted to devise a new evaluation method for helix measurement using a wedge artifact (WA) whose plane was treated as the tooth flank, and the high measurement capability of the developed GMM was verified. The results will provide a part of information to fully assess measurement uncertainty as our future work. This paper describes the evaluation results of the developed GMM for helix measurement using both a helix artifact and the WA, and discusses the effectiveness of the WA as a new artifact to evaluate the GMMs. © 2016 IOP Publishing Ltd.


Harano H.,National Metrology Institute of Japan NMIJ | Nolte R.,Physikalisch - Technische Bundesanstalt
Metrologia | Year: 2011

This paper provides an overview of high-energy quasi-monoenergetic neutron sources and facilities above 20 MeV around the world. Various technical matters are discussed which are required in characterizing the neutron fields by spectrometry, fluence and beam profile measurements. Important topics regarding the calibration of neutron detectors are also introduced with emphasis on beam monitoring, tail correction, background subtraction and fluence-to-dose conversion. Efforts to standardize the high-energy neutron fluence in Japan and by the German national metrology institute in collaboration with Belgian and South African institutions are also presented. © 2011 BIPM & IOP Publishing Ltd.


Fujimoto H.,National Metrology Institute of Japan NMIJ | Waseda A.,National Metrology Institute of Japan NMIJ | Zhang X.W.,High Energy Accelerator Research Organization
Metrologia | Year: 2011

The homogeneity of the lattice spacings of silicon single crystals from different origins was characterized. Strain measurements were performed on single crystals from NRLM3, NRLM4 and 28Si-10Pr11 ingots, which are all used to determine the Avogadro constant. NRLM3 and NRLM4 both exhibited clear striations, whereas almost no pattern was obtained for 28Si-10Pr11. The standard deviation of the lattice spacing of the single crystal obtained from 28Si-10Pr11 was 4.7 × 10-9, which enabled the lattice spacing to be determined with a standard uncertainty of 3 × 10-9. © 2011 BIPM & IOP Publishing Ltd.


Ohata M.,National Metrology Institute of Japan NMIJ | Matsubayashi N.,Japan National Institute of Advanced Industrial Science and Technology
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2014

X-ray absorption fine structure (XAFS) analysis with transmission mode was used to determine the percentages of hexavalent chromium {Cr(VI)} in total Cr in plastic certified reference materials (CRMs). Cr-K edge X-ray absorption near-edge structure (XANES) spectra were observed and the normalized pre-edge peaks of the spectrum where absorption data was summed was acquired for the determination of Cr(VI). Examination of different number of data point and range of photon energy for summed absorption of the pre-edge peak resulted in reproducible absorption data, though the measurements were carried out at different beam time and beam line. The concentrations of Cr(VI) in the plastic CRMs were also estimated from both the certified value of total Cr and the determined percentage of Cr(VI). The analytical procedure and the estimated concentrations can be useful for the determination of Cr(VI) in plastics with respect to RoHS (restriction of the use of hazardous substances in electrical and electronics equipment) directive. © 2014 Elsevier B.V.


Yamamoto T.,National Metrology Institute of Japan NMIJ
2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010 | Year: 2010

The scattering problem of rectangular waveguide T-junctions with discontinuities has still been considered. In slotted waveguide arrays at microwave and millimeter-wave band, especially, undesired reflection deteriorates the antenna characteristics and often imposes additional restrictions to the design; therefore, theoretical and experimental studies of waveguide scattering problems have been performed [1]-[4]. © 2010 IEEE.


Kojima M.,National Metrology Institute of Japan NMIJ | Kobata T.,National Metrology Institute of Japan NMIJ
Proceedings of the SICE Annual Conference | Year: 2010

A new calibration system for low-pressure transducers is now under development at NMIJ/AIST. To lower the minimum pressure of our present national standard using pressure balances, the pressure range of the system is designed for under 10 kPa in absolute mode. The pressure generation technique is based on a pressure balance. In this paper, the outline of the calibration system is described. © 2010 SICE.


Mizushima S.,National Metrology Institute of Japan NMIJ | Fujii K.,National Metrology Institute of Japan NMIJ
Metrologia | Year: 2016

The Bureau International des Poids et Mesures has carried out calibrations of the platinum-iridium kilogram mass standards by referencing the international prototype of the kilogram for the first time since the third periodic verification of national prototypes of the kilogram was carried out in 1988-92. This calibration campaign was designated 'Extraordinary Calibrations' in the second phase, in which two platinum-iridium kilogram mass standards of the National Metrology Institute of Japan were calibrated with a standard uncertainty of 3.5 μg. By adding these new calibration data into our data sets from 1991, we established our mass unit with a standard uncertainty of 3.3 μg by least-squares analysis using an exponential model, which is useful for compensating for mass increase after cleaning the mass standards. Moreover, it was found that our established mass unit following the Extraordinary Calibrations shifted against our previously maintained mass unit by -20.8 μg as of the beginning of 2015. The analysis with a linear model revealed that the amount of mass increase over time of some standards was significantly smaller than that suggested at the third periodic verification of national prototypes of the kilogram. The analysis with the exponential model gave an exponent of 0.217 with a standard uncertainty of 0.057. This suggests that the mass increase due to surface contamination cannot be explained by a diffusion-limited process. © 2016 BIPM & IOP Publishing Ltd.

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