著者

小松崎 俊彦 岩田 佳雄

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集C編 (ISSN:18848354)

巻号頁・発行日

vol.78, no.786, pp.420-430, 2012 (Released:2012-02-25)

参考文献数

10

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In this study, a virtual sound production system is developed where the difference frequency component appears as the secondary audible sound at a point of interference locally by the nonlinear interaction of two independently radiated ultrasounds while they travel directionally and intersect each other. The design of high-directive ultrasonic radiator, followed by the investigation of virtual sound production performance has been done theoretically as well as experimentally. It is known from these investigations that the fairly local sound reproduction in free space is possible, yet the sound pressure level of the secondary field is small. The results have also shown that the generated virtual sound area is dependent on both the difference frequency and the intersection angle of two carrier waves emitted by two sound sources.

著者

小松崎 俊彦 畑中 健介 岩田 佳雄

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.74, no.737, pp.75-82, 2008-01-25 (Released:2011-03-04)

参考文献数

14

被引用文献数

3 3

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Recent advances in digital signal processors have facilitated the development of active noise control (ANC) technology where the various kinds of researches as well as applications have been studied. In general, the sound waves propagate spherically in three dimensional space. Simply constituting SISO system using ordinary loudspeaker as a control source may cause interfered sound field with both attenuated and amplified nodes exist. By placing number of microphones and control sources can improve the range of quiet zone and many researches have been dedicated to this end, yet still limitations on implementation and cost cannot be neglected. On the other hand, the recent development of high-directional loudspeakers based on new sound production theory known as 'parametric array effect' has allowed sound transmission to a narrow range of acoustic space like 'spotlight'. This peculiar characteristic can be implemented as one measure for improving active noise control scheme controlling acoustic field locally without adversely influencing vicinal space. In the present study, a new approach for active control of sound in free space is developed using high directional parametric loudspeaker as a control source. Experiments are performed for the active control of noise generated by single source located in space, where the noise is attenuated by a control source at error microphone which evaluates sound level. Both normal and the parametric loudspeakers are tested as control sources and results are compared based on measurement of interfered sound field around the evaluation point. It is known that the suggested ANC system can mitigate sound locally but cause less influence on sound field in circumferential space.

著者

小松﨑 俊彦 岩田 佳雄

出版者

日本機械学会 = The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集C編 / Nihon Kikai Gakkai Ronbunshu, C Hen / Transactions of the Japan Society of Mechanical Engineers, Part C (ISSN:03875024)

巻号頁・発行日

vol.78, no.786, pp.420-430, 2012-01-01

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In this study, a virtual sound production system is developed where the difference frequency component appears as the secondary audible sound at a point of interference locally by the nonlinear interaction of two independently radiated ultrasounds while they travel directionally and intersect each other. The design of high-directive ultrasonic radiator, followed by the investigation of virtual sound production performance has been done theoretically as well as experimentally. It is known from these investigations that the fairly local sound reproduction in free space is possible, yet the sound pressure level of the secondary field is small. The results have also shown that the generated virtual sound area is dependent on both the difference frequency and the intersection angle of two carrier waves emitted by two sound sources. © 2012 The Japan Society of Mechanical Engineers.

著者

吉田 瑞人 岩田 佳雄 三枝 宏 小松﨑 俊彦

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集

巻号頁・発行日

vol.2018, pp.C-5, 2018

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<p>We prepared 7 cavity-backed disk plates which were same to baseline calibration plate used in COR test. Their membrane thickness increased by 0.2mm from 1.8mm to 3.0mm. CT(Characteristic Time)s were tested by a pendulum test instrument and CORs were measured through COR test using an air gun. The relation between CT and COR agreed with their linear characteristic described in "Technical Description of the Pendulum Test" by R&A and USGA for the thickness of 2.6mm or more. On the other hand, COR was constant and CT only increased for 2.4mm or less. Finally estimation of CT of the plates was simulated. As a result, we show that it is possible.</p>

著者

本江 哲行 佐藤 秀紀 岩田 佳雄 小松崎 俊彦

出版者

日本学術会議 「機械工学委員会・土木工学・建築学委員会合同IUTAM分科会」

雑誌

理論応用力学講演会 講演論文集 第52回理論応用力学講演会 講演論文集

巻号頁・発行日

pp.202, 2003 (Released:2003-03-25)

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ゴルフボールの飛距離に影響を与えるスピンに関する研究が多く行われているが,ロフト角,摩擦係数,反発係数,ボールの慣性モーメントなどのパラメータが衝突中のスピンに与える影響が明確になっていない. そこで,本研究では,先に提案したボールの材料の物性値と形状を考慮できる衝突モデルを用い,滑りと回転を考慮するために衝突モデルにスライダーと接線方法のばねを付加し,ゴルフボールとフェイスの斜め衝突のシミュレーショを行う.そして,ロフト角や摩擦係数,反発係数,慣性モーメントなどのパラメータと衝突特性の関係を調べる.

著者

岩田 佳雄 小松﨑 俊彦 浅沼 春彦 北山 弘樹

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.863, pp.18-00124, 2018 (Released:2018-07-25)

参考文献数

7

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If damping alloy is used as structural material, a structure with high damping performance can be produced and its vibration and noise can be reduced. Damping mechanism of the damping alloy is to convert vibration energy into thermal energy. The damping performance of the damping alloy is not as good as it is used in a dynamic damper. This paper proposes a method of enlarging equivalent loss factor of a damping alloy spring by using a negative spring constant and it is confirmed that the equivalent loss factor of a damping alloy cantilever becomes large by the attraction force of magnet used as the negative spring constant. Optimal design of the dynamic damper which consists of the damping alloy cantilever and a pair of magnets is explained. The vibration suppression effect due to the dynamic damper is demonstrated by means of measuring the compliance and the time history response by impact excitation. The vibration suppression effect depends on the vibrational amplitude due to nonlinearity of the attraction force of magnet but can be sufficiently expected in comparison with the case without the dynamic damper.

著者

程 輝 岩田 佳雄 小松崎 俊彦 佐藤 秀紀

出版者

一般社団法人日本機械学会

雑誌

セルオートマトン・シンポジウム講演論文集

巻号頁・発行日

vol.2001, pp.246-249, 2001-11-14

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Recently, Cellular Automata has been rapidly developed and widely used for analyzing many complex problems. In this paper, the phenomena that the sand grain which is initially and randomly spread on the surface of a square plate will crowd around some positions to generate shape of nodal line at natural modes is simulated by using Cellular Automata. Two moving patterns of sand grain are presented, one is the rolling of sand grain at micro-vibration condition or no-vibration position, and another is jump of sand grain at violent vibration or natural vibration condition. The former obeys usual Moore neighborhood rule, and the latter is defined that the jump distance is proportional to the initial vibrant velocity of plate in two directions of plate plane. The calculated procedures are list as following : first, a plate plane is divided into some uniformed grids in which the height of sand grain is defined as a state variable to be discussed in this paper ; then the height of sand grain caused its rolling movement is calculated ; finally, according to above-mentioned rules the height change of sand grain due to jump movement is calculated. The periodic boundary condition is used in simulation. The simple-supported condition at four boundary sides of the plate is mainly analyzed in this paper. In this case, the function of vibrant mode is directly used, and the mode shape is first shown ; then the Chladni's Figure which describes the distribution of sand grain in the plate surface is calculated by CA. Finally, using the same rule to simulate other constrained plates, such as free-boundary-condition and fix-boundary-condition. Two calculated results at mode order M=N=2 are shown in this paper. Due to the periodic boundary condition, sand grain will stack at four boundaries. But useful stacked shape should be observed in central wide area of plate. From calculated results of height distribution figures (Chladni's Figure) of sand grain in different constrained boundaries and mode situations, the nodal line at natural mode condition is clearly seen. Finally, the fact that CA is a useful method to describe the vibration mode is evidenced.