Meguro-ku, Japan
Meguro-ku, Japan

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Inoue T.,TokyoInstitute of Technology | Furukawa T.,TokyoInstitute of Technology | Yoshimi A.,Okayama University | Nanao T.,TokyoInstitute of Technology | And 13 more authors.
European Physical Journal D | Year: 2016

Abstract: A 129Xe nuclearspin oscillator with an artificial feedback was constructed, and detailed studies wereconducted on its performance, focusing on the frequency stability. As a result, the majorsources of drift of the precession frequency in the present spin oscillator setup wereidentified to be drifts of a solenoid current and an environmental magnetic field. Byintroducing stabilization systems for the current and the environmental field, whichyielded improvements by one order of magnitude on the solenoid current and by a factor ofthree on the environmental field, a frequency precision of 7.9 nHz was obtained for aone-shot measurement of 3 ×104s duration. We found, however, that the Allan deviationleveled off at around 30 μHz, indicating a strong need for the precisionmonitor of the experimental conditions represented by magnetometry. The frequencystability of the spin oscillator is discussed in relation to an experimental search for anelectric dipole moment of the 129Xe atom. Graphical abstract: [Figure not available: see fulltext.] © 2016, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Hou Y.,TokyoInstitute of Technology | Watanabe T.,Denso Corporation | Miyahara M.,TokyoInstitute of Technology | Matsuzawa A.,TokyoInstitute of Technology
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | Year: 2015

An all-digital time-domain ADC, abbreviated as TAD, is presented in this paper. All-digital structure is intrinsically compatible with the scaling of CMOS technology, and can satisfy the great demand of miniaturized and low-voltage sensor interface. The proposed TAD uses an inverter-based Ring-Delay-Line (RDL) to transform the input signal from voltage domain to time domain. The voltage-modulated time information is then digitized by a composite architecture namely "4-Clock-Edge-Shift Construction" (4CKES). TAD features superior voltage sensitivity and 1storder noise shaping, which can significantly simplify the power-hungry pre-conditioning circuits. Reconfigurable resolution can be easily achieved by applying different sampling rates. A TAD prototype is fabricated in 65 nm CMOS, and consumes a small area of 0.016mm2 . It achieves a voltage resolution of 82.7 μV/LSB at 10MS/s and 1.96 μV/LSB at 200 kS/s in a narrow input range of 0.1Vpp, merely under 0.6V supply. The highest SNR of TAD prototype is 61.36 dB in 20 kHz bandwidth at 10MS/s. This paper also analyzes the nonideal effects of TAD and discusses the potential solutions. As the principal drawback, nonlinearity of TAD can be compensated by the differential-setup and digital calibration. Copyright © 2015 The Institute of Electronics, Information and Communication Engineers.

Yokoi T.,Tokai University | Yokoyama Y.,Tokyo Institute of Technology | Mori H.,TokyoInstitute of Technology | Tomita K.,TokyoInstitute of Technology
Journal of Structural and Construction Engineering | Year: 2010

Finishing work greatly changes slab surface quality which influences floor performance. And, characteristics of concrete also greatly influence finishability. From such backgrounds, relations between mix proportion and finishiability were examined. 60 kinds of mix proportion used on actual sites and prepared for the examination were set, and finishability of them were measured. As a result, those were shown that unit water content and admixture addition ratio influenced finishability directly, and finishability was predictable clearly by a combination of both. Moreover, it was generally thought that water-bond ratio and fluidity were causes, the combination turned out to be the direct cause.

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