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Tsujii T.,Japan Aerospace Exploration Agency | Fujiwara T.,Japan Aerospace Exploration Agency | Kubota T.,Japan Aerospace Exploration Agency | Satirapod C.,Chulalongkorn University | And 3 more authors.
Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography | Year: 2012

Ionospheric anomaly is one of the major error sources which deteriorate the GNSS performance. In the equatorial region, effects of the ionospheric plasma bubbles are of great interest because they are pretty common phenomena, especially in the period of the high solar activity. In order to evaluate the GNSS performance under circumstance of the bubbles, an ionospheric scintillation monitor has been developed and installed in Bangkok, Thailand. Furthermore, a model simulating the ionospheric delay and scintillation due to the bubbles has been developed. Based on these developments, the effects of the simulated plasma bubbles are analyzed and their agreement with the real observation is demonstrated. An availability degradation of the GPS ground based augmentation system (GBAS) caused by the bubbles is exampled in details. Finally, an integrated GPS/INS approach based on the Doppler frequency is proposed to remedy the deterioration.

Fuse N.,Japan Central Research Institute of Electric Power Industry | Fukuchi T.,Japan Central Research Institute of Electric Power Industry | Mizuno M.,Applied Electromagnetic Research Institute | Fukunaga K.,Applied Electromagnetic Research Institute
Electronics and Communications in Japan | Year: 2016

Nondestructive, two-dimensional distribution measurement of rusting under opaque anticorrosion coating was carried out, using a terahertz camera, a quantum cascade laser, and a galvanic scanner. The measurement speed of the present method was found to be 11 times faster than the conventional raster scanning method based on time-domain spectroscopy. A signal-to-noise ratio exceeding 102 was confirmed for both systems, which enables the detection of minor rusting. © 2016 Wiley Periodicals, Inc.

Ohki Y.,Waseda University | Hirose Y.,Waseda University | Wada G.,Waseda University | Asakawa H.,Waseda University | And 3 more authors.
ICHVE 2012 - 2012 International Conference on High Voltage Engineering and Application | Year: 2012

Experiments were carried out using space charge distribution measurements as a major measurement method in order to find effective measures to suppress electrochemical migration (ECM) along the thickness direction of a printed wiring board (PWB). As a result, the following valuable knowledge was obtained. First, in a PWB consisting of paper/ phenol-resin composite and a copper electrode, the electrical resistivity of epoxy resin used as an adhesive layer to connect the composite and the electrode is usually higher than that of the composite. In such a case, ECM is easily grown in the PWB. The resistance against ECM was found to increase significantly if we use an adhesive layer with a similar electrical resistivity to the insulating material in a PWB. Another important fact is that the growth of ECM can be suppressed if silica nanofillers were added to epoxy resin in the case of an epoxy-based PWB. © 2012 IEEE.

Hosobuchi M.,Waseda University | Komatsu M.,Waseda University | Xie X.,Xian Jiaotong University | Cheng Y.,Xian Jiaotong University | And 5 more authors.
Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP | Year: 2013

Electrical insulation properties of low density polyethylene (LDPE) are still unclear, especially when it is degraded. In this regard, ultraviolet (UV) photons were irradiated to LDPE sheets at room temperature and 85°C and their absorption spectra were measured at frequencies from 0.5 to 3.0 THz and from 18 to 105 THz. A very broad absorption band with its peak at around 1.6 THz appears by the UV irradiation. In accord with this appearance, the infrared absorption peak due to a carbonyl structure increases. Quantum chemical calculations were carried out using 3-dimensional models with and without carbonyl groups. As a result, the model with carbonyl groups was found to have optically active modes at about 1.7 THz. From these results, the increase in absorption at 1.6 THz is assumed to be induced by oxidation. © 2013 IEEE.

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