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34 results on '"Akita, Manabu"'

1. Real-time Lightning 3D Imaging and Forecasting Project in Malaysia for Sustainable and Reliable Supply of Energy and Storm Disaster Early Warning

Author

Morimoto, Takeshi, primary, Ahmad, Mohd Riduan, additional, Baharuddin, Mohd Zafri, additional, Wang, Daohong, additional, Yamamoto, Kazuo, additional, Kudo, Takeshi, additional, Kahtani, Ammar Nasser Al, additional, Aziz, Mohamad Zoinol Abidin Abd, additional, Akita, Manabu, additional, Takayanagi, Yuji, additional, Kawasaki, Zen-Ichiro, additional, and Torii, Tatsuo, additional

Published
2023
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20. Upward Lightning Observed by LF Broadband Interferometer

Author

Takayanagi, Yuji, primary, Akita, Manabu, additional, Nakamura, Yoshitaka, additional, Yoshida, Satoru, additional, Morimoto, Takeshi, additional, Ushio, Tomoo, additional, Kawasaki, Zen-ichiro, additional, Wang, Daohong, additional, Takagi, Nobuyuki, additional, Sakurano, Hitoshi, additional, and Kubouchi, Yoshiyuki, additional

Published
2013
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26. What occurs in K process of cloud flashes?

Author

Akita, Manabu, primary, Nakamura, Yoshitaka, additional, Yoshida, Satoru, additional, Morimoto, Takeshi, additional, Ushio, Tomoo, additional, Kawasaki, Zen, additional, and Wang, Daohong, additional

Published
2010
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32. Long range detection of UWB radar using interpulse cyclic phase code.

Author

Watanabe, Masato, Akita, Manabu, and Inaba, Takayuki

Abstract

UWB impulse radar is generally used just for short range measurements because of transmitted power restrictions and due to its ultra wide bandwidth. In this paper, we consider the advantage of the coherent integration between pulses. The transmitted energy can be increased by adopting short PRI mode. The S/N ratio of the receiving signal is also able to be improved by the coherent integration. We suggest a method for enhancement of long range detection performance of UWB impulse radar using inter-pulse cyclic phase code, which mitigates the range ambiguity problem on short PRI mode. In this method, each transmitted pulse is modulated by P4 code and is modulated by the same phase in intra-pulse. The range of the target is obtained by adding the PRI delay and the corresponding range bin. We show the experimental results conducted on public way using 24GHz radar with power of 10mW based on the specified low power radio station to verify the effectiveness of the method. [ABSTRACT FROM PUBLISHER]

Published
2013

33. Leader process in 3D observed by VLF/LF broadband interferometer.

Author

Takayanagi, Yuji, Yoshida, Satoru, Akita, Manabu, Morimoto, Takeshi, Nakamura, Yoshitaka, Ushio, Tomoo, and Kawasaki, Zen

Abstract

We have been designing and developing a 3D lightning location system based on the broadband digital interferometry technique in VLF/LF band. The VLF/LF broadband digital interferometer (VLF/LF DITF) is able to locate lightning discharges such as return strokes, K events, and compact intracloud lightning discharges (CIDs), which are energetic breakdowns within thunderclouds several hundred kilometers away from the VLF/LF DITF. From July 2011 to now, a simultaneous observation of a VLF/LF band DITF and VHF broadband digital interferometers (VHF band DITF) were conducted in Kansai, Japan. We show the time series variation of an intracloud discharge initiated by a preliminary breakdown pulse train (PB), negative cloud to ground flash and intracloud discharge including K-event. VLF/LF DITF successfully located not only energetic breakdowns within thunderclouds but also leader processes. [ABSTRACT FROM PUBLISHER]

Published
2012
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34. Development of VLF/ LF Bands Interferometer and Its Initial Observations.

Author

Takayanagi, Yuji, Akita, Manabu, Nakamura, Yoshitaka, Yoshida, Satoru, Morimoto, Takeshi, Ushio, Tomoo, Kawasaki, Zen‐Ichiro, and Yamamoto, Kenji

Subjects
*ELECTROMAGNETIC radiation, *INTERFEROMETERS, *VERY low frequency electromagnetic method, *BROADBAND receivers, *LIGHTNING
Abstract

We have been developing an EM source location system using the VLF/ LF bands based on broadband digital interferometry to monitor lightning activity in a wide area. Since EM waves in VLF/ LF radiated by lightning discharges propagate a long distance, the VLF/ LF interferometer locates lightning discharges a few hundred kilometers away from the VLF/ LF interferometer. We conducted a lightning observation campaign using a prototype of a VLF/ LF band digital interferometer and VHF band digital interferometers in Darwin, Australia. The VLF/ LF radiation sources were located near those of the VHF source. We succeeded in locating the VLF/ LF radiation sources associated with return strokes near the ground. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 9-17, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22300 [ABSTRACT FROM AUTHOR]

Published
2013
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