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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

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. Source

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

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. Source

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

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. Source

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

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. Source

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

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. Source

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