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247 results on '"Takeda, Nobuo"'

4. Radio-Frequency-to-Optical Conversion using Acoustic and Optical Whispering Gallery Modes

Author

Yamazaki, Rekishu, Okada, Ayato, Noguchi, Atsushi, Akao, Shingo, Tsukahara, Yusuke, Yamanaka, Kazushi, Takeda, Nobuo, Tabuchi, Yutaka, Usami, Koji, and Nakamura, Yasunobu

Subjects
Physics - Optics, Physics - Applied Physics, Quantum Physics
Abstract

Whispering gallery modes (WGMs), circulating modes near the surface of a spheroidal material, have been known to exhibit high quality factors for both acoustic and electromagnetic waves. Here, we report an electro-optomechanical system, where the overlapping WGMs of acoustic and optical waves along the equator of a dielectric sphere strongly couple to each other. The triple-resonance phase-matching condition provides a large enhancement of the Brillouin scattering only in a single sideband, and conversion from the input radio-frequency signal exciting the acoustic mode to the output optical signal is observed., Comment: 13 pages, 10 figures

Published
2020
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8. Monitoring of bearing failure in composite bolted connections using ultrasonic guided waves: A parametric study

Author

Haynes, Colin, Todd, Michael, Nadabe, Takeaki, and Takeda, Nobuo

Subjects
Acoustics, Engineering
Abstract

Bearing damage in composite bolted connections (such as those commonly used in aerospace applications) is investigated through the application of ultrasonic guided waves. Specifically, identical macro-fiber composite sensor arrays were bonded to each of two identical composite plates. One plate was then inspected ultrasonically in the unloaded condition with bearing damage being introduced through successive uniaxial tensile tests, while the other plate was assessed while under load in the tensile testing machine. A scattering matrix approach is employed to characterize the interaction of the guided waves with the target bolt hole. The effects of applied load and the bolt fixture on the ultrasonic results are explored. A parametric study is carried out to determine the optimal actuation frequency and interrogation angle for this application. The results demonstrate that the system is capable of detecting bolt bearing damage as well as monitoring of the applied load in the elastic region.

Published
2014

30. Ultramultiple roundtrips of surface acoustic wave on sphere realization innovation of gas sensors

Author

Yamanake, Kazushi, Ishikawa, Santoru, Nakaso, Noritaka, Takeda, Nobuo, Sim, Dong Youn, Mihara, Tsuyoshi, Mizukami, Akio, Satoh, Ichitaro, Akao, Shingo, and Yusuke, Tsukahara

Subjects
Acoustic surface waves -- Properties, Gas-detectors -- Design and construction, Business, Electronics, Electronics and electrical industries
Abstract

The advantage of ball surface acoustic wave (SAW) is most fully appreciated when applied to a very thin sensitive film in a SAW sensor in which multiple roundrips enhance the sensitivity, but the attention loss is not very large. It is exemplified in a H2 gas sensor that realizes a wide sensing range of 10 ppm to 100% and realizes a relatively short response time of 20 s without heating the sensitive film.

Published
2006

33. Determination of the orthotropic elastic constants of thin PET film by an ultrasonic micro-spectrometer

Author

Okabe, Yoji, Takeda, Nobuo, Yanaka, Masa-aki, and Tsukahara, Yusuke

Subjects
Polyethylene terephthalate -- Evaluation, Spectrometer -- Usage, Reflectance -- Measurement, Stress analysis (Engineering) -- Models, Business, Electronics, Electronics and electrical industries
Abstract

A method for determining the elastic constants of polyethylene terephthalate (PET) film is examined. Topics include the calculation of the PET film's acoustic reflection coefficient, and the use of an ultrasonic microspectrometer.

Published
1999

37. Characteristics of silicon n(super +)-n(super -)-n(super +) diode with sub-micrometer n(super -) region

Author

Nishizawa, Jun-ichi, Takeda, Nobuo, and Masuoka, Fujio

Subjects
Silicon diodes -- Research, Ohm's law -- Observations, Electrical conductivity -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A silicon n(super +)-n(super -)-n(super +) diode with n(super -) region shorter than one micrometer shows ohmic characteristics which depend on the length of n(super -) region. This is despite the fact that the diode has many space-charges in the n(super -) region. The diode's conductance is inversely proportional to the cube of the length of the n(super -) region. However, diodes with n(super -) region longer than two micrometer show the usual space-charge-limited conduction.

Published
1996

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