過去の学会誌一覧

Vol.32 No.4 通巻120号 (2005年/平成17年)

研究 高周波スプリットビーム方式を用いたプランクトン計測装置の開発
Development of High Frequency Acoustic Split-beam System for Zoo Plankton Measurement
*1 Masaki OGATA (Furuno Electric Co., Ltd.)
*2 Masahiko FURUSAWA, Bo-Kyu HWANG (Tokyo University of Marine Science and Technology)
Abstract:
We developed a high frequency split beam (SB) scientific echo sounder to measure the target strength of a zooplankton in situ. There are some issues for high frequency split beam method, namely, an accuracy of transducer, a high speed processing of phase detection and a calibration method. We discussed about the following provisions: Piezocomposite transducer, high speed phase detection device for mobile phone and tungsten carbide sphere.
尾形 正樹,古澤 昌彦, 黄 普奎 9(247)
Active Time Reversalによる音響通信の基礎研究
A Basic Research on Active Time Reversal Communication
*1 Takuya SHIMURA, Hiroshi OCHI, Yoshitaka WATANABE (Marine Technology Research and Development Program, Marine
Technology Center, JAMSTEC)
Abstract:
We have researched on the application of time reversal waves to the underwater acoustic technology. Time reversal waves enable a desired signal to converge to the focus, even in unknown and inhomogeneous media. As time reversal waves converge to a "point" at any range, their focusing property is quite different from that of the conventional beam forming method. In this study, the basic research on time reversal communication is carried out. By using time reversal, the reflected and refracted waves are converged to the focus, the signal level received at the focus is increased and the symbol interferences are reduced. However, in order to ensure the communication channel only with time reversal, it is necessary to install many transducers of time reversal array. So, in this study, it is proposed to combine the focusing effect of time reversal waves and conventional adaptive filter. After most of the multi-path waves are utilized by using time reversal, unfocused waves, which appear like "noise", are removed by adaptive filter. The simulations in shallow water are performed and it is concluded that this proposed method makes more accurate communication to the long distance possible than the conventional method.
志村 拓也,越智  寛, 渡邊 佳孝 16(254)
解説 大陸棚調査の現状と展望 -海上保安庁による精密海底地形・地殻構造探査- 春日  茂 26(264)
2004年度第3回談話会要旨 国際学会におけるキャビテーションに関する研究動向 岡村 共由 33(271)
米国地球物理学連合2004年秋季大会 望月 将志 39(277)
第147回米国音響学会研究発表会-創立75周年記念大会- 蜂屋 弘之 44(282)
2004年度IEEE国際超音波シンポジウム報告 東 隆,川畑 健一, 梅村 晋一郎 48(286)
随想 JAMSTECにおける超音波水槽の建設 中西 俊之 52(290)
こぼれ話 ぶどうから作ったロッシェル塩受波器 鎌田 弘志 55(293)
企業紹介 株式会社システムインテック概要 59(297)
会記事 61(299)