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14 results on '"Ikeda, Takehiro"'

1. Marine Propeller Optimum Design in Wake Flow of Energy Saving Device

Author

Segawa, Kohei, Ikeda, Takehiro, Ando, Satoko, Kimura, Koyu, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Okada, Tetsuo, editor, Suzuki, Katsuyuki, editor, and Kawamura, Yasumi, editor

Published
2021
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5. Estimation of Postural Control Strategy During Continuous Perturbation

Author

Nur Fatin Fatina bt. Mohd Ramli, Ogawa Sho, Ikeda Takehiro, and Yamamoto Shin-ichiroh

Subjects
Control theory, Joint angle, Collective variables, Perturbation (astronomy), Negative correlation, Dynamic balance, Versa, Mathematics, Postural control
Abstract

Stability is an important aspect for every moving object and millions of people spend a good deal of their time on their feet for standing, walking, or running. Compared to static balance, dynamic balance with presence of external perturbation requires more complex strategy. The purpose of this study was to investigate the multi-segment of human postural control strategy organization in continuous perturbation balance task between ankle-hip angle as collective variable. We examined the transition of Center of Mass (COM)-Center of Pressure (COP) and ankle-hip angle pattern in moving platform balance paradigm. Eight healthy young adults stood on a moving platform in the anterior-posterior direction continuously within the frequency range 0.2–0.8 Hz and vice versa with eyes opened. COM, COP, and ankle-hip angle changed from in-phase to anti-phase at a certain point frequency of support surfaces. From the cross-correlation coefficient calculation, higher frequency shows negative correlation between the ankle-hip angle which mean these two variables were moving in the different phase direction. These results indicate that joint angle sway also could be one of the collective variables in order to determine postural strategy determination.

Published
2018

7. TDMA-Based Adaptive Modulation with Dynamic Channel Assignment for High-Capacity Communication Systems

Author

Ikeda, Takehiro, Sampei, Seiichi, and Morinaga, Norihiko

Subjects
Communications traffic -- Management, Wireless communication systems -- Design and construction, Business, Electronics, Electronics and electrical industries, Transportation industry
Abstract

This paper proposes a time-division multiple-access (TDMA)-based adaptive modulation scheme with dynamic channel assignment (AMDCA) to achieve high-capacity communication systems under dynamically changing propagation path and traffic conditions. The proposed method measures the received carrier-to-noise plus interference power ratio (C/(N + I)) of each TDMA slot to search available slots as well as to find out the optimum modulation parameters for each terminal, thereby effectively combining the effect of mitigating both spatially distributed electric field strength variation by the slow adaptive modulation and spatially and temporally distributed traffic variation by the dynamic channel assignment (DCA). Computer simulation confirms that the proposed AMDCA system can achieve approximately three times higher system capacity than the conventional fixed channel assignment (FCA) using QPSK. Index Terms--Cellular systems, dynamic channel assignment, quadrature amplitude modulation, slow adaptive modulation systems, time-division multiple-access.

Published
2000

9. Effects of Forward Speed of a Ship on Added Resistance in Waves.

Author

Kashiwagi, Masashi, Ikeda, Takehiro, and Sasagawa, Takuma

Abstract

The article presents a study of the wave resistance relative to a ship's forward speed. The Enhanced Unified Theory (EUT) was deemed useful for evaluating the wave-amplitude function, and to confirm the applicability of the EUT, measurements of wave-induced ship motions and added resistance were done using a modified Wigley model at several Froude numbers, and the results compared with computed ones. Conclusions gathered centered on the zero-speed case, the Doppler effect, shorter wavelengths and a correction factor.

Published
2009

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