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  • 中野 公彦
    日本機械学会論文集C編
    2013年 79 巻 801 号 1227-1236
    発行日: 2013年
    公開日: 2013/05/25
    ジャーナル フリー
  • 齊藤 美羽子, 吉村 卓也, 丸山 新一, 伊庭 周作
    日本機械学会論文集C編
    2012年 78 巻 789 号 1741-1748
    発行日: 2012年
    公開日: 2012/05/25
    ジャーナル フリー
    In order to reduce the noise level in the cabin, it is important to extract the characteristics of acoustic system (dynamic properties of the cavity). When frequency response functions (FRFs) of the acoustic system are measured, acoustic excitation by an audio speaker is generally used and its capabilities have been already illustrated[1]. However, to expand the availability of the acoustic excitation, it is necessary to reduce the number of excitation points and to predict the FRF with respect to the point where it was not actually excited (the unexcited FRF). It has been well known that in order to predict the unexcited FRF, a set of modal parameter can be used, where the auto FRF is thought to be included in the data set. However, for the acoustic system the auto FRF is hardly measured because the speaker is not able to apply the excitation at an exact point, but to apply a volume velocity at a small area. Therefore, this paper presents a new method to predict the unexcited FRF under the condition that the auto FRF is not included in the data set. In this paper, modal parameters of the acoustic system of a real automobile cabin are estimated, and the FRF is predicted by the proposed approach. The predicted FRFs are compared with the measured FRFs.
  • 石鍋 善郎, 吉村 卓也, 黄 惟, 赤松 博道, 和田 靖彦
    Dynamics & Design Conference
    2016年 2016 巻 364
    発行日: 2016年
    公開日: 2017/06/19
    会議録・要旨集 フリー

    In automotive development processes, noise and vibration of a vehicle are predicted using CAE. However, sometimes it happens that the frequency response functions (FRFs) of numerical model and those of the actual model do not correspond with each other. Therefore, a method for efficiently analyzing the factors of lack of precision is demanded to improve the accuracy of numerical model. Therefore, the method of finding out the parts with insufficient accuracy in numerical model is investigated by utilizing sensitivity analysis. The proposed method is applied to a real automotive structure of what we call cutbody (the front half of the body). As a result, it is suggested that the proposed method can indicate the parts in the numerical model with insufficient accuracy from the viewpoint of the mass or stiffness property.

  • 長松 昌男, 鈴木 浩平, 吉村 卓也, 中野 光雄
    日本機械学会論文集 C編
    1996年 62 巻 601 号 3452-3458
    発行日: 1996/09/25
    公開日: 2008/02/26
    ジャーナル フリー
    A sound source identification technique based on the acoustic double holography method was proposed in the previous paper. This method can achieve high resolution in sound source identification compared with the acoustic holography method. Furthermore, this method is more convenient than the nearfield acoustic holography method for measurement and calculation. However, this method still has the problem that comparatively high-level subsidiary source images appeared in the reconstructed image patterns which might have caused misjudgment. In this paper, a specific zone filtering technique applied to reconstructive calculation for reducing the subsidiary source image is proposed. By this technique, the level of subsidiary source image can be reduced without decrease in resolution of a real noise source image. Finally, in order to examine the effectiveness of the filtering technique, computer simulation and experimentation are carried out.
  • ―実験セットアップ状態に起因する系統誤差の影響―
    高橋 一善, 吉村 卓也
    自動車技術会論文集
    2013年 44 巻 1 号 99-104
    発行日: 2013年
    公開日: 2018/01/24
    ジャーナル フリー
    伝達経路解析の入力同定に用いる周波数応答関数(FRF)の測定において生じるばらつきを評価し,FRFのばらつきが同定値に及ぼす影響について考察する.本研究では実験セットアップにより生じるばらつきを考える.実験セットアップをやり直してFRFを測定する手順を繰り返し,生じるばらつきを評価する.
  • 相互FRF推定法の提案と6自由度FRFの推定
    細矢 直基, 吉村 卓也
    日本機械学会論文集 C編
    2004年 70 巻 694 号 1672-1679
    発行日: 2004/06/25
    公開日: 2011/03/04
    ジャーナル フリー
    Rotational FRFs have not been measured in experimental modal analysis even though the importance of rotational FRFs have been recognized recently. Consequently it is difficult to utilize the FRFs on the basis of vibration testing for the structure modification analysis. The authors have proposed an estimation of the auto FRFs in rotation of structures. In the method a T-shaped rigid block whose inertia properties were known was attached to the measurement point on the structure. The estimation of three-degree-of-freedom (3-DOF) FRFs (one DOF in rotation and two DOFs in translation) of the beam structure using the T-shaped rigid block was demonstrated. The effect of estimated rotational FRFs against the random noise of measured FRFs were evaluated as a Reliability Factor. In this paper the estimation method of the cross FRFs in rotation and the reliability of the estimated FRFs are presented. A new rigid block whose overview is the cross-shape is designed for measuring 6-DOF FRFs. The 6-DOF FRFs of the beam structure is estimated. The structure modification analysis of 3D-rahmen structure based on experimental data is carried out.
  • *橋場 嶺, 吉村 卓也
    Dynamics & Design Conference
    2023年 2023 巻 357
    発行日: 2023年
    公開日: 2024/03/01
    会議録・要旨集 認証あり

    Improving quietness is an important issue in automotive design. Many studies have been reported on the use of a stiffness sensitivity to identify effective design changes. However, calculating a stiffness sensitivity using experimental measurements requires a large number of strain sensors, making it difficult to use in automobile design. Therefore, we propose a simplified method to evaluate strain energy focusing on elastic deformation and to calculate stiffness sensitivity more easily. The validity of the proposed method is confirmed using a simple flat-plate FEM model.

  • 石鍋 善郎, 吉村 卓也
    年次大会
    2015年 2015 巻 G1001104
    発行日: 2015/09/13
    公開日: 2017/06/19
    会議録・要旨集 フリー
    Internal noise detected by passengers inside of the cabin of a car or an aircraft is caused by coupling vibration between the structure and the internal sound field. For practical purpose, it is most efficient to suppress the structural mode associated with acoustic dominant mode in order to reduce noise level in the cabin. Therefore, it would be beneficial to find the structure dominant mode. In this report, first, we suggested the determination technique for acoustic or structure dominant mode in the coupled system. Furthermore, in order to identify natural modes precisely, we examined experimental methods for frequency response measurement and modal parameter identification methods for the coupled system. This study proposes a determination technique for the natural mode of the coupled system. The validity of the proposed method is examined through the numerical simulation. In addition, the effectiveness of the multi-point excitation and acoustic excitation for the coupled system is illustrated.
  • 玉置 元
    騒音制御
    2002年 26 巻 6 号 378-381
    発行日: 2002/12/01
    公開日: 2009/10/06
    ジャーナル フリー
  • 宗 迪, 玉置 元, 吉村 卓也
    年次大会
    2015年 2015 巻 J2320105
    発行日: 2015/09/13
    公開日: 2017/06/19
    会議録・要旨集 フリー
    It is important to investigate the effects on a seated human body exposed to whole-body vibration. We have shown the effects on a human body based on the changes in the seated postures exposed to vertical excitation. We, however, have not dealt with fore-and-aft or lateral excitation. Accordingly, the major objective of this study is to investigate the relationship between the vibration characteristics on a seated human body and the seated postures exposed to fore-and-aft, lateral and vertical excitations, respectively. Ten seated male subjects were measured at their heads in fore-and-aft, lateral, vertical, and roll and pitch directions, in terms of seat-to-head transmissibility and driving-point apparent mass, under random vibration excitations in the three directions. The random fore-and-aft and lateral excitations were in the range of 1-20 Hz, and the vertical excitation was in the range of 1-30 Hz. Each magnitude of the random excitations was 1.0 m/s^2 rms. Three different seated postures were examined: upright, relaxed, and the intermediate thereof. As a result, the resonance frequencies of 2-3 Hz and 10-2 Hz were obtained for for-and-aft excitation and lateral excitation, respectively. The results also showed that, under vertical excitation, the resonance points vary depending on the seated postures, while they do not under fore-and-aft lateral excitations. Moreover, the transmissibility of the pitch direction durng vertical and fore-and-aft excitation could be considered as being coupled vibration.
  • *橋場 嶺, 吉村 卓也, 田中 裕之, 井上 浩一, 藤田 帝智
    Dynamics & Design Conference
    2022年 2022 巻 360
    発行日: 2022年
    公開日: 2023/03/25
    会議録・要旨集 認証あり

    In recent years, the demand for improvement of ride comfort in automobiles has been increasing, and the demand for quietness in the vehicle interior also increased. In particular, noise in the low-frequency range is one of the most important interior properties and has been the subject of various studies, but there have been few studies on the transient noise generated in a vehicle cabin when a shock input is applied. In this study, we attempt to improve the transient response to reduce the booming noise in the low frequency range caused by the shock input. First, the vibration characteristics of the test vehicle were determined based on data obtained from experimental measurements. As a result, it was found that ceiling deformation, which adversely affects vibration noise, occurs at a specific frequency. Next, based on the experimental measurements, a sensitivity analysis was performed to determine the appropriate mass addition, and mass addition was actually performed on the test vehicle. As a result, the transient response to shock input was improved as the sensitivity analysis predicted.

  • 高野 賢太, 吉村 卓也
    日本機械学会関東支部総会講演会講演論文集
    2014年 2014.20 巻 20905
    発行日: 2014/03/14
    公開日: 2017/06/19
    会議録・要旨集 フリー
    This study is proposes a sensitivity analysis for improvement of transient response of time history data. For improvement of vibration characteristics of structures it is necessary to find the appropriate location where the structural modification is needed, i.e., mass or stiffness modification. The sensitivity analysis is one of the effective approaches to find out the modification location, However it has been conducted only in the frequency domain. To improve the transient response it is impossible to directly apply the frequency-domain sensitivity analysis. In this study, a sensitivity analysis for the transient response is presented, and the validity of the method is examined through experimental application.
  • 河野 俊夫, 吉村 卓紘, 河合 将史, 石川 勝美
    農業施設
    2005年 35 巻 4 号 221-228
    発行日: 2005/03/25
    公開日: 2011/09/05
    ジャーナル フリー
    農業施設からの汚水を排出する時, あるいは農業用水を利用する際には水の浄化が必要であるが, 現在の浄化方法は一般にコストがかかる。天然に豊富に産生する岩石は多孔質で表面に電荷を帯びており, 懸濁液中の物質を吸着する性質があり, 低コストな汚水浄化方法の一つとして利用することが期待される。しかし, 天然岩石の物質吸着能は定量的には未だ明らかでない。
    そこで天然岩石の物質吸着能を定量的に明らかにするため, メチレンブルーを吸着物質として, 初期最高濃度10~20ppm, 溶液温度10~30℃の範囲における吸着実験を行った。供試岩石には, 塩基性片岩, 蛇紋岩, 中国産石英斑岩, 日向産石英斑岩の4種類を用いた。Langmuir の吸着速度式と, IUPACの類型でI型に属する吸着等温式を組み合わせた, 岩石の物質吸着プロセスモデルを提案し, 吸着プロセスのシミュレーションを行った。
    岩石によるメチレンブルー吸着量の経日変化は, 提案した岩石の物質吸着プロセスモデルでシミュレーションできることがわかり, 岩石の物質吸着に関する基本特性値を推定することができた。
    その結果, 吸着速度は溶液温度が10℃や30℃の場合よりも20℃が大きいことが分かった。また, 最終的な吸着量はどの供試岩石についても30℃で最も多く, 8.02×10-7~9.03×10-7g/grocks, であり, この値は10, 20℃に比べて4~4.5倍であることが分かった。
  • 迎 恵利, 吉村 卓也, 今村 一哉, 柏原 真, 梶原 陽介
    日本機械学会関東支部総会講演会講演論文集
    2015年 2015.21 巻 10602
    発行日: 2015/03/20
    公開日: 2017/06/19
    会議録・要旨集 フリー
    This study proposes a sensitivity analysis for improvement of transient response of time history data. For improvement of vibration characteristics of structures, it is necessary to find the appropriate location for the structural modification. However, it is difficult to apply sensitivity analysis to time history data since the sensitivity analysis has been conducted only in the frequency domain. This study presents a sensitivity analysis for the transient response of time history data. As an example, the proposed method is applied to a construction equipment in order to reduce a peak of vibration response in the time domain.
  • 松村 雄一, 増田 新, 滝田 好宏, 井上 剛志, 杉山 博之
    日本機械学会論文集C編
    2011年 77 巻 777 号 1622-1629
    発行日: 2011年
    公開日: 2011/05/25
    ジャーナル フリー
  • 細矢 直基, 吉村 卓也
    日本機械学会論文集 C編
    2006年 72 巻 713 号 37-44
    発行日: 2006/01/25
    公開日: 2011/03/04
    ジャーナル フリー
    The acceleration sensors are generally attached to the structure to measure the response in FRF (frequency response function) measurement. The mass of the sensor often have some effect on dynamic characteristics of the structure. This paper proposes a new method for compensation of sensor's mass effect in FRF measurements. In the method, inertial force of the sensor's mass is regarded as external force acting on the structure;FRF is corrected so as to remove the external force effect. The compensated FRFs of an accuracy are evaluated by a Reliability Factor which it is installed in this paper. The compensation method for the use of multiple sensors is also presented. The method is validated by applying it to a brass plate structure. The usability of the method is demonstrated via measuring FRFs of a car body.
  • *辻 善夫, 藤本 望夢, 眞田 明, 村上 浩二, 松田 亮, 廣田 義明, 吉村 卓也
    Dynamics & Design Conference
    2023年 2023 巻 313
    発行日: 2023年
    公開日: 2024/03/01
    会議録・要旨集 認証あり

    Monitoring technology such as predictive maintenance and anomality detection during cutting process has been required. A wireless tool holder with acceleration sensors has been developed for monitoring tool vibration. For advancing functionally of the device, we have been proposed a method using inverse filters for estimating cutting force and torque from acceleration sensor signals during machining. In this study, excitation forces (x direction force, y direction force) on a tool mounted on the holder of machining center were estimated by the proposed method. Firstly, inverse filters were determined from single-input, single-output signals by excitation experiment on non-operating state. Secondly, the proposed method was examined by estimating an impulse signal.

  • 馬 平, 吉村 卓也, 鈴木 浩平
    日本機械学会論文集 C編
    2001年 67 巻 653 号 30-36
    発行日: 2001/01/25
    公開日: 2008/02/26
    ジャーナル フリー
    This paper presents a new speech recognition system using wavelet analysis. The framework of the system based on wavelet analysis is described with the efficiency and accuracy considered. The proposed system has following advantages comparing to conventional speech recognition systems based on short time Fourier transform : the non-stationary noise such as impulsive noise can be extracted and reduced, the database for speech recognition can be effectively compressed, and high recognition accuracy can be obtained for the burst speech which conventional systems have never been able to well recognize. Furthermore, the influence of data compression on recognition accuracy and recognition speed is examined.
  • 小野寺 裕, 柳沼 慎治, 細矢 直基, 吉村 卓也
    Dynamics & Design Conference
    2012年 2012 巻 444
    発行日: 2012/09/18
    公開日: 2017/06/19
    会議録・要旨集 フリー
    This paper discusses an estimation method of auto frequency response function using additional masses. The input forces in vibration testing cannot be applied to the excitation points of the structure, if it is difficult to secure space for excitation to structures with complex shapes. In order to improve the accuracy of estimated unmeasured frequency response function, maximum likelihood method for reducing random noise effect is introduced in this method. Additionally, reliability factor of the estimated unmeasured frequency response function is obtained by considering the propagation of random noise from measured frequency response functions. The feasibility of the method is verified by comparing the unmeasured frequency response function of a lower arm that is a part of car's suspension system estimated by the method and obtained by impact testing.
  • 宇津野 秀夫, 丸山 真一, 古屋 治, 高橋 正樹, 西原 崇, 小沢田 正, 萩原 一郎
    日本機械学会論文集C編
    2012年 78 巻 789 号 1306-1314
    発行日: 2012年
    公開日: 2012/05/25
    ジャーナル フリー
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