研究者紹介システム

奥園 健
オクゾノ タケシ
大学院工学研究科 建築学専攻
助教
土木・建築工学関係
Last Updated :2022/09/16

研究者情報

所属

  • 【主配置】

    大学院工学研究科 建築学専攻
  • 【配置】

    工学部 建築学科

学位

  • 博士(工学), 大分大学
  • 高品質な音響設計の実現に向けた音響数値解析技術の開発

授業科目

ジャンル

  • 科学・技術 / 建築

コメントテーマ

  • 音場解析
  • 吸音測定
  • 残響室

研究活動

研究キーワード

  • 音響数値解析
  • 時間領域有限要素法
  • Partition of Unity Finite Element Method
  • 吸音材
  • 織編物・不織布
  • 微細穿孔板
  • 建築音響
  • 室内音響シミュレーション
  • 有限要素法
  • 音響材料
  • 波動音響シミュレーション
  • 建築・環境音響学
  • 窓の遮音性能

研究分野

  • 社会基盤(土木・建築・防災) / 建築環境、建築設備

委員歴

  • 2020年04月 - 2022年03月, 日本音響学会, 建築音響研究委員会幹事
  • 2019年06月 - 2021年05月, 日本建築学会, 技術報告集委員会委員
  • 2019年04月 - 現在, 日本建築学会, 音響数値解析小委員会幹事
  • 日本騒音制御工学会, ノイズマップ分科会幹事
  • 2022年04月 - 2024年03月, 日本音響学会, 建築音響研究委員会副委員長

受賞

  • 2022年03月 日本音響学会, 第23回学生優秀発表賞, Partition of Unity FEM による室内音場解析―頑健な平面波数の設定に関する検討―

    向江 俊一(指導学生)

    将来の音響学の発展を担う若手研究者を奨励するため,日本音響学会春季又は秋季研究発表会において優秀な発表を行った学生会員に贈呈される, 日本国

    国内学会・会議・シンポジウム等の賞

  • 2019年08月 日本建築学会近畿支部, 優秀発表賞, 等価流体モデルに基づく高性能吸音要素の誤差特性に関する研究

    田丸加奈子, (指導学生)

    日本国

    国内学会・会議・シンポジウム等の賞

  • 2017年01月 日本建築学会環境工学委員会, 2016 年度 日本建築学会大会(九州)学術講演会 若手優秀発表賞, 通気性膜吸音体を取り扱うための 1 階常微分方程式に基づく時間領域有限要素法

    吉田卓彌, (指導学生)

  • 2017年 日本音響学会, 第16回学生優秀発表賞, 通気性膜吸音体アレイの吸音特性に関する実験的検討

    上西 宏治, (指導学生)

  • 2016年 日本建築学会近畿支部, 優秀発表賞, 通気性膜アレイの吸音特性に関する数値解析的研究

    上西宏治, (指導学生)

  • 2012年09月 日本音響学会, 粟屋潔学術奨励賞, スプライン音響要素を用いた時間領域有限要素法の分散誤差低減

    奥園 健

  • 2007年05月 日本建築学会九州支部, 建築九州賞(研究新人賞), 有限要素法による室内音場の時間応答解析-反復解法の選定と小ホール内音場解析-

    奥園 健

  • 2022年04月 日本建築学会, 日本建築学会奨励賞, Predicting absorption characteristics of single-leaf permeable membrane absorbers using finite element method in a time domain

    奥園健

    会員により近年中に発表された独創性・萌芽性・将来性のある建築に関する優れた論文等の業績, 日本国

    学会誌・学術雑誌による顕彰

論文

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    Wave-based acoustics simulation methods such as finite element method (FEM) are reliable computer simulation tools for predicting acoustics in architectural spaces. Nevertheless, their application to practical room acoustics design is difficult because of their high computational costs. Therefore, we propose herein a parallel wave-based acoustics simulation method using dissipation-free and dispersion-optimized explicit time-domain FEM (TD-FEM) for simulating room acoustics at large-scale scenes. It can model sound absorbers with locally reacting frequency-dependent impedance boundary conditions (BCs). The method can use domain decomposition method (DDM)-based parallel computing to compute acoustics in large rooms at kilohertz frequencies. After validation studies of the proposed method via impedance tube and small cubic room problems including frequency-dependent impedance BCs of two porous type sound absorbers and a Helmholtz type sound absorber, the efficiency of the method against two implicit TD-FEMs was assessed. Faster computations and equivalent accuracy were achieved. Finally, acoustics simulation of an auditorium of 2271 m3 presenting a problem size of about 150,000,000 degrees of freedom demonstrated the practicality of the DDM-based parallel solver. Using 512 CPU cores on a parallel computer system, the proposed parallel solver can compute impulse responses with 3 s time length, including frequency components up to 3 kHz within 9000 s.

    MDPI AG, 2022年01月23日, Buildings, 12 (2), 105 - 105, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Shunichi Mukae, Takeshi Okuzono, Kimihiro Sakagami

    Partition of unity finite element method with plane wave enrichment (PW-FEM) uses a shape function with a set of plane waves propagating in various directions. For room acoustic simulations in a frequency domain, PW-FEM can be an efficient wave-based prediction method, but its practical applications and especially its robustness must be studied further. This study elucidates PW-FEM robustness via 2D real-scale office room problems including rib-type acoustic diffusers. We also demonstrate PW-FEM performance using a sparse direct solver and a high-order Gauss–Legendre rule with a recently developed rule for ascertaining the number of integration points against the classical linear and quadratic FEMs. Numerical experiments investigating mesh size and room geometrical complexity effects on the robustness of PW-FEM demonstrated that PW-FEM becomes more robust at wide bands when using a mesh in which the maximum element size maintains a comparable value to the wavelength of the upper-limit frequency. Moreover, PW-FEM becomes unstable with lower spatial resolution mesh, especially for rooms with complex shape. Comparisons of accuracies and computational costs of linear and quadratic FEM revealed that PW-FEM requires twice the computational time of the quadratic FEM with a mesh having spatial resolution of six elements per wavelength, but it is highly accurate at wide bands with lower memory and with markedly fewer degrees of freedom. As an additional benefit of PW-FEM, the impulse response waveform of quadratic FEM in a time domain was found to deteriorate over time, but the PW-FEM waveform can maintain accurate waveforms over a long time.

    MDPI AG, 2022年01月20日, Acoustics, 4 (1), 53 - 73, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Marie Mimura, Takeshi Okuzono, Kimihiro Sakagami

    The development of windows with high sound insulation performance is essential for preventing the infiltration of traffic noise and the leakage of room noise. A numerical prediction is an effective means of reducing sound insulation testing and development costs to develop a quietness window. As a numerical prediction method for the sound reduction index, the finite element method (FEM) is useful in dealing with structure-acoustic problems. This study was conducted as a pilot study toward developing an accurate numerical model to predict the sound reduction index of a double window. We discussed the accuracy of an FEM model for predicting the diffuse incidence sound reduction index of double windows through a comparison with measured values for a simplified realistically scaled double window. The FE results were compared with measured ones for eight cases with and without a frame absorber. Results showed that the best match to measured values is obtained when using a frame absorber in all the perimeters inside the air cavity. Also, a better agreement is obtained at frequencies of 160–2,000Hz in other cases. However, a marked discrepancy is found at frequencies above 2,000Hz and below 160Hz. Possible reasons for the discrepancies are also discussed.

    Acoustical Society of Japan, 2022年01月01日, Acoustical Science and Technology, 43 (1), 32 - 42, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Shunichi Mukae, Takeshi Okuzono, Kanako Tamaru, Kimihiro Sakagami

    Plane-wave-enriched finite element method (FEM), an efficient wave-based prediction method, uses shape functions incorporating a set of plane waves propagating in various directions to enhance the sound field approximation capability. The method can be an efficient wave-based acoustic solver for room acoustic simulations because it can simulate wave phenomena in rooms accurately with markedly fewer finite elements in spatial discretization than those used for standard FEM. However, several aspects remain to be addressed before its use for practical room acoustic simulations. Accurate sound absorber modelings able to address their frequency and incident angle dependence of absorption characteristics present extremely important issues. This paper presents a proposal of a method of implementing an extended-reaction model of microperforated panel (MPP) and permeable membrane (PM) sound absorbers into a room acoustic solver with plane-wave-enriched FEM. First, we demonstrate the validity of the proposed method in comparison with theoretical values in which impedance tube problems including three sound absorbers composed of MPP and PM are used. Then, the effectiveness over standard FEM is demonstrated via 2D real-scale office problems with the three MPP-PM sound absorbers.

    Elsevier BV, 2022年01月, Applied Acoustics, 185, 108383 - 108383, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Yohei Tsukamoto, Kaoru Tamai, Kimihiro Sakagami, Takeshi Okuzono, Yoshihiro Tomikawa

    Acoustical Society of Japan, 2021年11月01日, Acoustical Science and Technology, 42 (6), 350 - 353, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Takumi Yoshida, Kimihiro Sakagami

    Recent wave-based room acoustic simulations in the time domain can incorporate frequency-dependent absorbing boundary conditions (BCs), by which time responses including a broad frequency component are calculable with a single computational run. However, their performance over the frequency-domain method remains poorly understood. This paper presents a discussion of the capabilities of a recently developed implicit time-domain finite element method (TD-FEM) for room acoustics simulation by comparison with a fourth-order accurate frequency-domain FEM (FD-FEM). First, the implicit TD-FEM accuracy is examined via an impedance tube problem, having frequency-dependent absorbing BCs at the tube end, where a specific acoustic admittance ratio of rigidly backed porous sound absorbers is imposed. Results indicate that the implicit TD-FEM has the same solution convergence rate as that of FD-FEM. The solution converges to the FD-FEM solution when using a sufficiently small time interval. A performance comparison of both methods is then made using two real-scale 2D room acoustic problems in an office room and a complexly shaped concert hall. Numerical results show that the implicit TD-FEM can be useful for acoustic simulation in practical-sized rooms at broad frequency ranges with markedly smaller computational costs than those of FD-FEM while maintaining similar accuracy.

    Elsevier BV, 2021年11月, Applied Acoustics, 182, 108212 - 108212, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    This paper presents a proposal for an efficient room acoustic solver with dissipation-free and dispersion-optimized explicit time-domain FEM (TD-FEM), with investigation of its applicability for broadband room acoustic modeling from three numerical experiments. Recently, FEM-based room acoustic solvers have attracted great attention because of their strength in handling complex geometries. However, the development of higher-efficiency solvers is unavoidable to perform acoustic modeling of real-size rooms at kilohertz frequency with small discretization error: the dispersion error. The present paper first formulates a novel room acoustic solver with dissipation-free fourth-order accurate explicit TD-FEM using a three-step time integration method. A dispersion-optimized solver is further proposed in which dispersion error is minimized in the axial and diagonal directions at a specific frequency under given spatial resolution mesh or elements, by which the approximation capability at higher frequencies is enhanced without any additional computational cost. The performance of the optimized solver in broadband acoustic simulation using cubic elements is then examined in comparison with the original fourth-order accurate solver and the standard implicit TD-FEM. Finally, higher efficiency of the optimized solver is also demonstrated for acoustic simulation in a larger rectangular room discretized with rectangular and distorted hexahedral elements.

    Acoustical Society of Japan, 2021年09月01日, Acoustical Science and Technology, 42 (5), 270 - 281, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Kanako Tamaru, Takeshi Okuzono, Shunichi Mukae, Kimihiro Sakagami

    In this study, we assessed the reduction in the computational costs of a room-acoustics solver by the partition of unity finite-element method (PUFEM), particularly addressing the element matrix construction process with numerical integration rules. The PUFEM enriches the approximation of sound fields by incorporating a general solution of the Helmholtz equation into shape functions. Plane wave enrichment is applied herein. In plane-wave-enriched FEM, the construction of element matrices using a high-order Gauss–Legendre quadrature is the main numerical operation with a long computational time. To reduce the computational time of the room-acoustics solver with plane-wave-enriched FEM, in this report, we describe our exploration of efficient integration rules via an ideal plane wave propagation problem in a duct. We present two integration rules: a well-used existing rule extended to the low-frequency range and another derived by the linear regression of the relationship between the number of wavelengths included in each element and the minimum number of integration points required for solution convergence. Numerical results revealed that both rules produce accurate frequency responses in a broad frequency range. However, the rule obtained by linear regression outperforms the extended rule.

    Acoustical Society of Japan, 2021年09月01日, Acoustical Science and Technology, 42 (5), 231 - 240, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Yui Sugimoto, Kimihiro Sakagami

    Accurate boundary modelings that address the frequency-dependent sound absorption characteristics of various sound absorbers are crucial for wave-based room acoustic simulation. In time-domain simulations, however, a computationally demanding convolution appears in frequency-dependent impedance boundary conditions. The present paper proposes a room acoustic solver with a fourth-order accurate explicit TD-FEM, incorporating a frequency-dependent absorbing boundary condition efficiently using a recursive convolution method, namely the auxiliary differential equation (ADE) method. Its performance against the fourth-order accurate frequency-domain FEM is examined via 2D real-scale room acoustic problems, solving a sound propagation in an office room up to 4.5 kHz. Firstly, we describe briefly the formulation of the proposed room acoustics solver based on the explicit TD-FEM. Then, the discretization error property of the proposed method is evaluated via an impedance tube problem, including a frequency-dependent impedance boundary of porous sound absorber. Finally, the accuracy and efficiency of the proposed method are demonstrated with the comparison of frequency-domain FEM solver, which uses a sparse direct solver for the solution of the linear system at each frequency. Results showed the proposed method can perform an acoustic simulation with significantly low computational costs compared to the frequency-domain solver while keeping an acceptable level of accuracy.

    Institute of Noise Control Engineering (INCE), 2021年08月01日, INTER-NOISE and NOISE-CON Congress and Conference Proceedings, InterNoise21, 263 (5), 1120 - 1129, 英語, 国際共著していない

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Kimihiro Sakagami, Midori Kusaka, Takeshi Okuzono, Shigeyuki Kido, Daichi Yamaguchi

    There are various measures currently in place to prevent the spread of coronavirus (COVID-19); however, in some cases, these can have an adverse effect on the acoustic environment in buildings. For example, transparent acrylic partitions are often used in eating establishments, meeting rooms, offices, etc., to prevent droplet infection. However, acrylic partitions are acoustically reflective; therefore, reflected sounds may cause acoustic problems such as difficulties in conversation or the leakage of conversation. In this study, we performed a prototyping of transparent acrylic partitions to which a microperforated panel (MPP) was applied for sound absorption while maintaining transparency. The proposed partition is a triple-leaf acrylic partition with a single acrylic sheet without holes between two MPP sheets, as including a hole-free panel is important to prevent possible droplet penetration. The sound absorption characteristics were investigated by measuring the sound absorption in a reverberation room. As the original prototype showed sound absorption characteristics with a gentle peak and low values due to the openings on the periphery, it was modified by closing the openings on the top and sides. The sound absorption performance was improved to some extent when the top and sides were closed, although there remains the possibility of further improvement. For this study, only the sound absorption characteristics were examined in the prototype experiments. The effects during actual use will be the subject of future study.

    UCL Press, 2021年07月10日, UCL Open Environment, 2

    研究論文(学術雑誌)

  • Midori Kusaka, Kimihiro Sakagami, Takeshi Okuzono

    Micro-perforated panels (MPPs) are one of the most promising alternatives to conventional porous sound-absorbing materials. Traditionally, the theory of the sound absorption properties of MPPs is based on the assumption that MPPs are a homogeneous material with identical pores at regular intervals. However, in recent years, some MPPs have not met these conditions, and although a variety of designs have been created, their properties and prediction methods were studied in only fewer works. In this paper, considering the wide variety of MPP designs, we made a trial production of heterogeneous MPPs, which are MPPs with holes of different diameters, and studied the prediction method applicable to these MPPs. We measured the normal incidence sound absorption characteristics of those MPPs, backed by a rigid backing and air-cavity in-between, in an impedance tube. The prediction method proposed in this work is to treat the heterogeneous MPPs as combinations of several homogeneous components, and to combine them after applying the existing theory on homogeneous MPPs to each component. As a result, except in a few cases, the measured and predicted values of the absorption properties agreed relatively well. We also found that the arrangement of the holes in the material and the depth of the back cavity affected the agreement between the measured and predicted results.

    MDPI AG, 2021年07月05日, Acoustics, 3 (3), 473 - 485, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    The development of a computationally efficient wave-based room acoustic solver is an active re- search area in the architectural acoustics field, thanks to both the progress in computational technology and attractiveness for accurate acoustic modeling in virtual spaces. The authors have been proposed an efficient acoustic solver with fourth-order accurate explicit FEM using a dispersion-reduced low-order element and a modified time integration and shown its applicability to real-scale room acoustic modeling up to several kilohertz. However, the method has the drawback of having a dissipation property. The present paper proposes dissipation-free explicit FEMs for acoustic simulations to overcome the draw- back. We also present the dispersion-optimized method that can produce an accurate result at a high frequency. As a numerical demonstration of the two proposed methods’ effectiveness, we show that the developed two acoustic solvers have higher accuracy and efficiency than the standard implicit FEM via acoustic simulations in a cubic room with impedance boundaries.

    Silesian University Press, Gliwice, Poland, 2021年07月, Proceedings of the 27th International Congress on Sound and Vibration, No.1397, 1 - 8, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Yohei Tsukamoto, Kimihiro Sakagami, Takeshi Okuzono, Yoshihiro Tomikawa

    As a basic study of a practical method for predicting the sound insulation performance of windows, this report presents a study of the sound reduction index of windows with single glazing, below a critical frequency. First, the results calculated by an existing theory for a single plate for the sound reduction indices are compared with measured results of actual windows to assess the theory’s applicability for evaluating the sound insulation performance of windows. Then, a regression analysis is employed to measure the results of a certain number of actual windows to explore a further development of a more practical prediction. The following findings were obtained: (1) Sound reduction indices of actual fixed windows are predictable using Sewell’s transmission theory for a single plate. However, sound reduction indices of openable windows, especially those of sliding windows, are strongly affected by gaps in the window frame. Therefore, predicting sound reduction indices of all windows accurately is difficult if using only one theory. (2) The frequency slope of the window reduction index is much lower than that of the mass law. Regression analyses indicate that the frequency slope of the reduction index of all examined windows is 3.0 dB per octave, on average.

    UCL Press, 2021年05月07日, UCL Open Environment, 2

    研究論文(学術雑誌)

  • Kimihiro Sakagami, Takeshi Okuzono

    In this study, we first point out the possible acoustic problems associated with the post-pandemic operation of built environments. In particular, we focus on the problem of acoustic deficiency due to the lack of absorption. This deficiency, which is likely to be encountered in most enclosed spaces in a range of establishments, is due to the reduced number of audience members or users of the space as a result of social distancing. As one of the promising solutions to this problem, we introduce a sound absorption technique using three-dimensional (3D) space sound absorbers developed through our recent research projects. Significantly, the type of sound absorber proposed herein is made of materials that are especially suited to hygiene considerations. The materials are microperforated panels (MPPs) and permeable membranes (PMs), both of which are easily washable and sanitised. Furthermore, we point out that 3D-MPP or PM space absorbers possess the additional value of aesthetic designability.

    UCL Press, 2020年11月18日, UCL Open Environment, (1), 1 - 10

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2020年11月01日, Acoustical Science and Technology, 41 (6), 837 - 840, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2020年11月01日, Acoustical Science and Technology, 41 (6), 819 - 822, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Kimihiro Sakagami, Midori Kusaka, Takeshi Okuzono, Shigeyuki Kido, Daichi Yamaguchi

    Acoustical Society of Japan, 2020年09月01日, Acoustical Science and Technology, 41 (5), 784 - 787, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Kimihiro Sakagami, Midori Kusaka, Takeshi Okuzono, Shinsuke Nakanishi

    In this study, we discuss the effect of the manufacturing accuracy of a microperforated panel (MPP) produced by 3D printers on acoustic properties through measured and calculated results as a pilot study. The manufacturing costs of MPPs have long been one of their shortcomings; however, with recent developments in the manufacturing process, low-cost MPPs are now available. In a further attempt at reducing the cost, 3D printing techniques have recently been considered. Cases of trial production of MPPs manufactured by 3D printing have been reported. When introducing such new techniques, despite the conventional microdrill procedure, manufacturing accuracy can often become an issue. However, there are few studies reporting the effect of manufacturing accuracy on the acoustic properties in the case of 3D-printed MPPs. Considering this situation, in this pilot study, we attempted to produce MPPs with circular and rectangular perforations using a consumer 3D printer of the additive manufacturing type. The hole sizes of the specimens were measured, and the accuracy was evaluated. The normal incidence absorption coefficient and specific impedance were measured using an impedance tube. The measured results were compared with the theoretical values using Guo’s model. Through these basic studies, the MPPs produced by an additive manufacturing 3D printer demonstrated good sound absorption performance; however, due to the large deviations of parameters, the agreement with the theoretical values was not good, which suggests that it is difficult to predict the acoustic properties of MPPs made by a consumer-grade additive manufacturing 3D printer.

    MDPI AG, 2020年08月14日, Acoustics, 2 (3), 605 - 616

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    A room acoustic simulator using time-domain finite element method (TD-FEM) has been broadened its applicable range as a room acoustic design tool, recently. In the acoustic TD-FEM, constructing various sound absorber model is of crucial importance to perform reliable simulations. However, an accurate time-domain extended-reacting sound absorber model, which can take account for both frequency and incident angle dependence of sound absorption characteristics, has not been developed sufficiently due to the difficulties of modeling. The major difficulty is how to reflect frequency-dependent absorption characteristics efficiently in time-domain because its direct incorporation involves a convolution computation. In the present paper, a recently proposed auxiliary differential equations (ADE) method is applied to model the frequency-dependent locally-reacting impedance boundaries as a preliminary of constructing efficient extended-reacting model. The ADE method can reflect frequency-dependent behaviors in time-domain efficiently by solving additional first-order differential equations instead of the convolution computation. Numerical impedance tube problems demonstrate that the present TD-FEM can accurately simulate broadband absorption characteristics of various porous absorbers up to 10 kHz.

    2020年08月, Proceedings of Inter-Noise 2020, 英語, 国際共著していない

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Yohei Tsukamoto, Yoshihiro Tomikawa, Kimihiro Sakagami, Takeshi OKuzono, Hidetoshi Maikawa, Yusuke Komoto

    As described herein, the sound insulation performance of a double window with absorbent materials on the perimeter of its cavity is studied experimentally. Two experiments are used to measure the sound reduction indices. The first experiment was performed with a double window composed of commercially available products. The second was conducted with a model constructed of two acrylic panels: a simplified model of a double window with a cavity between the panes. As the result of the first experiment, the improvement in reduction index obtained by the attached absorbent was around 4 dB. In the second experiment, though some negative effect was observed at low frequencies, the increase in reduction index was about 12 dB at maximum. Consequently, the following findings were obtained: (1) Acoustic transmission characteristics of a double window are affected mainly by resonances of two types: mass-air-mass resonance of window panes and the air cavity, and the acoustic mode resonances of the air cavity in-between; (2) acoustic mode resonance is suppressed by attaching absorbent materials on the inside of the cavity of window. Consequently, the sound reduction index increases.

    ELSEVIER, 2020年08月, Applied Acoustics, 165, 107317, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2020年07月01日, Acoustical Science and Technology, 41 (4), 689 - 692, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Kimihiro Sakagami, Takeshi Okuzono, Hirotaka Suzuki, Nao Koyanagi, Masahiro Toyoda

    The authors propose a space sound absorber made of a permeable membrane (PM), including woven or non-woven fabrics in three-dimensional shapes, e.g., cylinder, rectangle, etc. The proposed absorbers are examined by experimental measurements and boundary element analyses, and it is found that they can be effectively used especially for middle and high frequencies. In order to develop these absorbers for wider applications, it would be desirable to give them additional values and functions, particularly to elaborate on their design. Supposing that they could also be used for lighting equipment, such as lampshades as one of the applications, pilot studies on pseudo-cylindrical, and pseudo-spherical PM space absorbers with uneven surfaces produced by paper-folding (origami technique) are carried out. The pseudo-cylindrical concave curves (PCCC) shell shape has been proven as a suitable form for a lampshade, and the pseudo-spherical concave curves (PSCC) shell shape is an application of PCCC. In this paper, PCCC and PSCC shell shapes are applied to three-dimensional PM space absorbers, and trials are conducted using PMs selected by flow resistance measurements and preliminary simulations. The sound absorptivity of the specimens is measured in a reverberation chamber, and their absorptivity is 0.6 (PCCC case) and 0.4 (PSCC case) at mid-high frequencies.

    INT INST ACOUSTICS & VIBRATION, 2020年06月, INTERNATIONAL JOURNAL OF ACOUSTICS AND VIBRATION, 25 (2), 243 - 247, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takumi Yoshida, Takeshi Okuzono, Kimihiro Sakagami

    This paper presents a proposal of a time domain room acoustic solver using novel fourth-order accurate explicit time domain finite element method (TD-FEM), with demonstration of its applicability for practical room acoustic problems. Although time domain wave acoustic methods have been extremely attractive in recent years as room acoustic design tools, a computationally efficient solver is demanded to reduce their overly large computational costs for practical applications. Earlier, the authors proposed an efficient room acoustic solver using explicit TD-FEM having fourth-order accuracy in both space and time using low-order discretization techniques. Nevertheless, this conventional method only achieves fourth-order accuracy in time when using only square or cubic elements. That achievement markedly impairs the benefits of FEM with geometrical flexibility. As described herein, that difficulty is solved by construction of a specially designed time-integration method for time discretization. The proposed method can use irregularly shaped elements while maintaining fourth-order accuracy in time without additional computational complexity compared to the conventional method. The dispersion and dissipation characteristics of the proposed method are examined respectively both theoretically and numerically. Moreover, the practicality of the method for solving room acoustic problems at kilohertz frequencies is presented via two numerical examples of acoustic simulations in a rectangular sound field including complex sound diffusers and in a complexly shaped concert hall.

    MDPI AG, 2020年05月28日, Applied Sciences, 10 (11), 3750 - 3750, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Koji Uenishi, Kimihiro Sakagami

    Permeable membranes (PMs), which are air-permeable fabrics made from various natural or chemical fibers that are thinly woven or non-woven, are attractive sound-absorbing materials. The simplest PM absorber is a single-leaf PM absorber (PMSG) with a non-locally reacting rigid backed air cavity in which a PM is placed in front of a rigidly backed air cavity. A honeycomb-backed single-leaf PM absorber (PMHC), which has a locally reacting air cavity, is also well known. However, the two PM absorbers have shortcomings in their diffuse field absorption coefficients attrib- utable to the backing air cavity design. To overcome those shortcomings, we intro- duce a PM absorber array (PMAR): a single-leaf PM absorber with multiple locally reacting air cavities of different depths. As described herein, to present PMAR benefits, we experimentally compare the diffuse field absorption charac- teristics of the three single-leaf PM absorbers with different air cavity designs. Reverberation absorption coefficient measurements were taken using nine thin permeable membranes made of three chemical fibers, each having different flow resistance and surface density. Results show that PMAR is an effective sound ab- sorbing structure to overcome the shortcomings related to the diffuse field absorp- tion coefficients of PMSG and PMHC. Material property effects on permeable membranes are also demonstrated.

    Institute of Noise Control Engineering (INCE), 2020年05月20日, Noise Control Engineering Journal, 68 (3), 237 - 245, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, M Shadi Mohamed, Kimihiro Sakagami

    Predicting room acoustics using wave-based numerical methods has attracted great attention in recent years. Nevertheless, wave-based predictions are generally computationally expensive for room acoustics simulations because of the large dimensions of architectural spaces, the wide audible frequency ranges, the complex boundary conditions, and inherent error properties of numerical methods. Therefore, development of an efficient wave-based room acoustic solver with smaller computational resources is extremely important for practical applications. This paper describes a preliminary study aimed at that development. We discuss the potential of the Partition of Unity Finite Element Method (PUFEM) as a room acoustic solver through the examination with 2D real-scale room acoustic problems. Low-order finite elements enriched by plane waves propagating in various directions are used herein. We examine the PUFEM performance against a standard FEM via two-room acoustic problems in a single room and a coupled room, respectively, including frequency-dependent complex impedance boundaries of Helmholtz resonator type sound absorbers and porous sound absorbers. Results demonstrated that the PUFEM can predict wideband frequency responses accurately under a single coarse mesh with much fewer degrees of freedom than the standard FEM. The reduction reaches O(10^-2) at least, suggesting great potential of PUFEM for use as an efficient room acoustic solver.

    MDPI, 2020年03月13日, Applied Sciences, 10 (6), 1969, 英語, 国際誌, 国際共著している

    [査読有り]

    研究論文(学術雑誌)

  • HOSHI Kazuma, HANYU Toshiki, OKUZONO Takeshi, SAKAGAMI Kimihiro, YAIRI Motoki, HARADA Shinji, TAKAHASHI Seiji, UEDA Yasutaka

    This paper presents the absorption performance of honeycomb-backed micro perforated panel (MPP) absorbers, which are needed to improve the acoustics of an existing 91 m^3 small meeting room where the reverberation time is over two seconds from 250 Hz to 2 kHz, for comfortable speech communication. In Japan, MPPs are difficult to use combustible materials, particularly, panels with holes for interior walls owing to fire regulations. Therefore, we implemented the MPP absorber as an additional attachment that can be hung on walls and ceilings. First, the absorption characteristics of the MPP absorber were designed to reduce reverberation times at mid-frequency using an electroacoustical equivalent theory. Then, a wave-based finite element method simulation was used to determine the absorber placement. Absorption coefficients of the honeycomb-backed MPP absorber were also measured in an irregularly shaped reverberation chamber. Finally, the effect of the installed MPP absorbers was checked by acoustic parameter measurements. As a result, we observed that the reverberation time was reduced under 1.5 s in all frequencies, the equivalent absorption area doubled, the early decay time values were also reduced from 2.7 s to 1.0 s at 1 kHz, the clarity (C50,mid) increased by more than 5 dB, and the speech transmission index (STI) value increased from 0.55 to 0.67 by one rank up.

    2020年01月, Applied Acoustics, 157, 107000, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • YAIRI Motoki, SAKAGAMI Kimihiro, OKUZONO Takeshi

    2019年09月, Acoustical Science and Technology, 40 (5), 325 - 335, 英語

    [査読有り]

    研究論文(学術雑誌)

  • YOSHIDA Takumi, OKUZONO Takeshi, SAKAGAMI Kimihiro

    2019年09月, Proceedings of 23rd International Congress on Acoustics, 763 - 770, 英語

    [査読有り]

    研究論文(学術雑誌)

  • OKUZONO Takeshi, SAKAGAMI Kimihiro, OTSURU Toru

    This paper presents an overview of the applicability of implicit time-domain FEM (TD-FEM) for room acoustics simulation, which has fourth-order accuracy in both space and time. First, the TD-FEM algorithm is presented with explanations of dispersion-reduced finite elements for spatial discretization and a time integration method for time discretization. The theoretical dispersion error property is also shown. Use of the dispersion-reduced scheme presents benefits in terms of accuracy, stability and convergence of an iterative solver, which have a marked effect on the computational cost. Then, the applicability of TD-FEM is demonstrated using two numerical examples on room acoustics simulation in the kilohertz frequency range, which are acoustics simulations of a simply shaped concert hall and simulation of reverberation absorption coefficient measurements. In numerical examples of concert hall analysis, comparison with a conventional TD-FEM presents the efficiency of the dispersion-reduced TD-FEM. Modeling accuracy of non-locally reacting permeable membrane sound absorbers for the TD-FEM is presented through simulation of reverberation room method.

    2019年09月, Proceedings of 23rd International Congress on Acoustics, 6070 - 6077, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • OKUZONO TAKESHI, SHIMIZU NORIYASU, SAKAGAMI KIMIHIRO

    Permeable membranes (PMs), which are air-permeable thin woven fabrics or non-woven fabrics, are attractive sound-absorbing materials used to control acoustics in buildings. Although the absorption characteristics of various PM absorbers have been studied extensively, it has not been established how to incorporate PMs into a wave-based acoustic simulation method known as the time-domain finite element method (TD-FEM). This paper presents a numerical model of limp PMs for TD-FEM as well as a computationally efficient TD-FEM for predicting sound fields including PMs. The limp PM model incorporates effects of both sound-induced vibration of PMs and the air permeability of PMs. Consequently, two mate- rial parameters are considered: the surface density and flow resistance of PMs. Verification of the limp PM model and efficiency evaluation of TD-FEM were first performed with an impedance tube problem. Then, reverberation absorption coefficients of single-leaf PM absorbers with a non-locally reacting rigid backed air cavity were predicted through simulation of a reverberation absorption coefficient measurement using the present TD-FEM at frequencies of 100 Hz to 2.5 kHz. The predicted results were compared with measured and theoretical values. To demonstrate the applicability of present TD-FEM, eight PMs, each with different flow resistance and surface density, were considered for comparison. Results revealed that the present TD-FEM with the limp PM model can predict the magnitude relation of absorption characteristics of single-leaf PM absorbers attributable to differences of material properties of PMs.

    2019年08月, Applied Acoustics, 151, 172 - 182, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • OKUZONO TAKESHI, NITTA TAKAO, SAKAGAMI KIMIHIRO

    2019年05月, Acoustical Science and Technology, 40 (3), 221 - 224, 英語, 国際誌

    [査読有り]

    研究論文(学術雑誌)

  • TOYODA MASAHIRO, FUNAHASHI KOTA, OKUZONO TAKESHI, SAKAGAMI KIMIHIRO

    Three-dimensional, permeable membrane space sound absorbers have been proposed as practical and economical alternatives to three-dimensional, microperforated panel space sound absorbers. Previously, the sound absorption characteristics of a three-dimensional, permeable membrane space sound absorber were predicted using the two-dimensional boundary element method, but the prediction accuracy was impractical. Herein, a more accurate prediction method is proposed using the three-dimensional boundary element method. In the three-dimensional analysis, incident waves from the elevation angle direction and reflected waves from the floor are considered, using the mirror image. In addition, the dissipated energy ratio is calculated based on the sound absorption of a surface with a unit sound absorption power. To validate the three-dimensional numerical method, and to estimate the improvement in prediction accuracy, the results are compared with those of the measurements and two-dimensional analysis. For cylindrical and rectangular space sound absorbers, three-dimensional analysis provides a significantly improved prediction accuracy for any shape and membrane sample that is suitable for practical use.

    2019年05月, Sustainability, 11 (9), 2714, 英語, 国際誌

    [査読有り][招待有り]

    研究論文(学術雑誌)

  • SAKAGAMI KIMIHIRO, OKUZONO TAKESHI, SOMATOMO YU, FUNAHASHI KOTA, TOYODA MASAHIRO

    In this communication, the sound absorption characteristics of rectangular-shaped plane space sound absorbers without any backing structure using permeable membranes (PMs) are measured by reverberation room method. First, three types of PMs, in this study woven fabrics, are selected with different flow resistances and surface densities. They are prepared in the plane rectangular-shaped space absorbers of two different sizes. The measured results are discussed through comparison with the existing theoretical and measured results for absorbers of the other shapes or configurations. The present results and discussion demonstrate that the reverberation absorption coefficients of the proposed absorbers are low at low frequencies and converge to a moderately high value at high frequencies. Especially, ones with higher flow resistance than the air impedance converge to a value greater than 0.5, which is a theoretically estimated maximum absorption coefficient of infinite single-leaf PM. This is inferred to be attributed mainly to area effect. From these results the proposed absorbers can be used effectively despite of their very simple structure. Also it is found that the proposed absorber can offer higher sound absorption than permeable membrane absorbers of other shapes or configuration. Regarding the effect of the size, the absorbers of smaller size offer higher absorption coefficients regardless of material properties of the PMs used in the experiments.

    2019年04月, Sustainability, 11 (7), 2185, 英語, 国際誌

    [査読有り]

    研究論文(学術雑誌)

  • Asniawaty Kusno, SAKAGAMI KIMIHIRO, OKUZONO TAKESHI, TOYODA MASAHIRO, OTSURU TORU, Rosady Mulyadi, Kusno Kamil

    2019年03月, Sustainability, 11 (5), 1476, 英語

    [査読有り]

    研究論文(学術雑誌)

  • TAKAHASHI KATSUTOSHI, YAIRI MOTOKI, OKUZONO TAKESHI, SAKAGAMI KIMIHIRO, TOYODA MASAHIRO

    2019年01月, Acoustical Science and Technology, 40 (1), 52 - 55, 英語

    [査読有り]

    研究論文(学術雑誌)

  • OKUZONO TAKESHI, SAKAGAMI KIMIHIRO

    2018年09月, Acoustical Science and Technology, 39 (5), 362 - 365, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • RELATIONSHIP BETWEEN SOUND RADIATION FROM SOUND-INDUCED AND FORCE-EXCITED VIBRATION

    YAIRI Motoki, SAKAGAMI Kimihiro, OKUZONO Takeshi

    2018年07月, Proc of 25th Internaltional Congress on Sound and Vibration, No.287, 1 - 8, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • IMPLEMENTATION EXPERIMENT OF A HONEYCOMB-BACKED MPP SOUND ABSORBING PANEL IN A MEETING ROOM

    HOSHI Kazuma, HANYUToshiki, SAKAGAMI Kimihiro, OKUZONO Takeshi, YAIRI Motoki, HARADA Shinji, TAKAHASHI Seiji, UEDA Yasutaka

    2018年07月, Proc of 25th Internaltional Congress on Sound and Vibration, No.1049, 1 - 8, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • A THREE-DIMENSIONAL TIME-DOMAIN FINITE ELEMENT METHOD BASED ON FIRST-ORDER ORDINARY DIFFERENTIAL EQUATIONS FOR TREATING PERMEABLE MEMBRANE ABSORBERS

    YOSHIDA Takumi, OKUZONO Takeshi, SAKAGAMI Kimihiro

    2018年07月, Proc of 25th Internaltional Congress on Sound and Vibration, No.838, 1 - 7, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • AN EXPERIMANTAL STUDY ON THE ABSORPTION CHARACTERISTICS OF PERMEABLE MEMBRANE ABSORBERS ARRAY

    OKUZONO Takeshi, UENISHI Koji, SAKAGAMI Kimihiro, SHIMIZU Hikaru

    2018年07月, Proc of 25th Internaltional Congress on Sound and Vibration, No.48, 1 - 6, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • YOSHIDA Takumi, OKUZONO Takeshi, SAKAGAMI Kimihiro

    2018年05月, Noise Control Engineering Journal, 66 (3), 176 - 189, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Kimihiro Sakagami

    Microperforated panel (MPP) absorbers, which provide broadband sound absorption without the use of fibrous materials, have favorable material properties that support recyclability, flexibility of design, hygiene demands, and cleaning. Many earlier studies have specifically examined the development of absorbers themselves. However, to use the absorption performance of MPP absorbers sufficiently in room acoustic applications, it is beneficial to develop accurate prediction methods of sound fields in rooms with MPP absorbers. Such methods are expected to be useful for room acoustics design and absorber design tools. This study constructs a frequency domain finite element (FE) solver for acoustic simulations of a practical sized room with MPP absorbers. Then the accuracy and effectiveness are evaluated. In the FE solver, spatial domains are discretized by fourth-order accurate FEs in terms of dispersion error, and MPP absorbers are modeled using first-order hexahedral limp MPP elements that can deal with sound propagation in the backing structure of absorbers. First, the accuracy of present FE solver is demonstrated using impedance tube problems in comparison with conventional second-order accurate FEs. Results show higher convergence of solutions for the present FE solver. Then, exploration of an iterative solver for efficient multi-frequency analyses reveals that the recently developed CSQMOR is a faster and more stable solver. Finally, comparison with a conventional surface impedance model based on a locally reacting assumption confirms the effectiveness of present FE solver by presenting the importance of dealing with the incident angle dependence of reactance of a rigid-backed air cavity in the modeling of single leaf MPP absorbers. (C) 2017 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2018年01月, APPLIED ACOUSTICS, 129, 1 - 12, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • A first-order ODE based explicit time-domain FEM for room acoustic simulations

    OKUZONO Takeshi, YOSHIDA Takumi, SAKAGAMI Kimihiro

    2017年08月, Proc of inter.noise2017, 371 - 379, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • An implicit time-domain finite element scheme for sound field analysis with permeable membrane absorbers

    OKUZONO Takeshi, SAKAGAMI Kimihiro, KATSUYAMA Akihiro

    2017年07月, Proc of 24th Internaltional Congress on Sound and Vibration, NO.961, 1 - 8, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • Masahiro Toyoda, Kimihiro Sakagami, Mitsuru Okano, Takeshi Okuzono, Emi Toyoda

    Because microperforated panels (MPPs), which can be made from various materials, provide wide-band sound absorption, they are recognized as one of the next-generation absorption materials. Although MPPs are typically placed in front of rigid walls, MPP space sound absorbers without a backing structure, including three-dimensional cylindrical MPP space absorbers (CMSAs) and rectangular MPP space absorbers (RMSAs), are proposed to extend their design flexibility and easy-to-use properties. On the other hand, improving the absorption performance by filling the back cavity of typical MPP absorbers with porous materials has been shown theoretically, and three-dimensional MPP space absorbers should display similar improvements. Herein the effects of porous materials inserted into the cavities of CMSA5 and RMSAs are experimentally investigated and a numerical prediction method using the two-dimensional boundary element method is proposed. Consequently, CMSA5 and RMSAs with improved absorption performances are illustrated based on the experimental results, and the applicability of the proposed prediction method as a design tool is confirmed by comparing the experimental and numerical results. (C) 2016 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2017年01月, APPLIED ACOUSTICS, 116, 311 - 316, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Koji Uenishi, Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2017年, Acoustical Science and Technology, 38 (6), 322 - 325, 英語

    [査読有り]

    研究論文(学術雑誌)

  • 通気性膜を用いた立体型空間吸音体の吸音特性の3次元境界要素解析

    舟橋 康太, 豊田 政弘, 阪上 公博, 奥園 健

    日本音響学会, 2016年07月, 日本音響学会誌, 72 (7), 383 - 385, 日本語

    [査読有り]

    研究論文(学術雑誌)

  • 長方形要素を用いた陽的時間領域有限要素法による室内音場解析のための修正積分則

    吉田 卓彌, 奥園 健, 阪上 公博

    日本音響学会, 2016年07月, 日本音響学会誌, 72 (7), 367 - 373, 日本語

    [査読有り]

    研究論文(学術雑誌)

  • Motoki Yairi, Kimihiro Sakagami, Kosuke Nishibara, Takeshi Okuzono

    Although sound radiation from sound-induced vibration and from force-excited vibration of solid structures are similar phenomena in terms of radiating from vibrating structures, the general relationship between them has not been explicitly studied to date. In particular, airborne sound transmission through walls and sound radiation from structurally vibrating surfaces in buildings are treated as different issues in architectural acoustics. In this paper, a fundamental relationship is elucidated through the use of a simple model. The transmission coefficient for random-incidence sound and the radiated sound power under point force excitation of an infinite elastic plate are both analyzed. Exact and approximate solutions are derived for the two problems, and the relationship between them is theoretically discussed. A conversion function that relates the transmission coefficient and radiated sound power is obtained in a simple closed form through the approximate solutions. The exact solutions are also related by the same conversion function. It is composed of the specific impedance and the wavenumber, and is independent of any elastic plate parameters. The sound radiation due to random-incidence sound and point force excitation are similar phenomena, and the only difference is the gradient of those characteristics with respect to the frequency. (C) 2016 Acoustical Society of America.

    ACOUSTICAL SOC AMER AMER INST PHYSICS, 2016年07月, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 140 (1), 453 - 460, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Takumi Yoshida, Kimihiro Sakagami, Toru Otsuru

    This paper presents the applicability of an explicit time-domain finite element method (TD-FEM) using a dispersion reduction technique called modified integration rules (MIR) on room acoustics simulations with a frequency-independent finite impedance boundary. First, a dispersion error analysis and a stability analysis are performed to derive the dispersion relation and the stability condition of the present explicit TD-FEM for three-dimensional room acoustics simulations with an infinite impedance boundary. Secondly, the accuracy and efficiency of the explicit TD-FEM are presented by comparing with implicit TD-FEM using MIR through room acoustics simulations in a rectangular room with infinite impedance boundaries. Thirdly, the stability condition of the explicit TD-FEM is investigated numerically in the case with finite impedance boundaries. Finally, the performance of the explicit TD-FEM in room acoustics simulations with finite impedance boundaries is demonstrated in a comparison with the implicit TD-FEM. Although the stability of the present explicit TD-FEM is dependent on the impedance values given at boundaries, the explicit TD-FEM is computationally more efficient than the implicit method from the perspective of computational time for acoustics simulations of a room with larger impedance values at boundaries. (c) 2015 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2016年03月, APPLIED ACOUSTICS, 104, 76 - 84, 英語

    [査読有り]

    研究論文(学術雑誌)

  • 固体音放射と空気音透過の関係に関する一考察-単層無限大弾性板の既存近似解を用いた基礎的検討-

    矢入 幹記, 阪上 公博, 奥園 健, 西原 康介

    日本音響学会, 2016年02月, 日本音響学会誌, 72 (2), 68 - 72, 日本語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2016年, Acoustical Science and Technology, 37 (1), 46 - 49, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Acoustic absorption mapping: wide-area estimation of acoustic absorption coefficient using airborne hyperspectral imagery

    OSHIMA Takuya, WAKAMATSU Kei, HIRAGURI Yasuhiro, OKUZONO Takeshi, TOMIKU Reiji, OKAMOTO Noriko, OTSURU Toru

    © 2016, German Acoustical Society (DEGA). All rights reserved. Recent advances in outdoor acoustic propagation modeling and simulation techniques have enabled wide-area environmental noise assessment as represented by noise mapping. However, among main input information for such an assessment, ground acoustic properties are not available as a geographical dataset, whereas topography is readily obtainable as a digital surface model (DSM). In this paper, a wide-area estimation technique of ground acoustic absorption coefficient using remote sensing is explored. The selected sensor is a CASI-3 airborne hyperspectral imager, which provides high spectral and spatial resolutions in visible and near-infrared optical wavelengths. Hyperspectral images of 34 bands with a ground sampling distance of 1 m was acquired for a region of approximately 1570x3730 m2. Simultaneously, ground acoustic properties were measured using an in-situ technique at 8 locations in the imaged region, each of which has 36 measurement points. A modeling process using single and multiple regression analyses derived a set of equations that estimates the acoustic absorption coefficient from 160 to 3150Hz one-third-octave bands using the optical spectral reflectance tracked down to 3 bands. The acoustic absorption maps obtained by applying the derived model to the entire image provided qualitative validity of the model.

    2016年, Proc of inter.noise2016, 1857 - 1864, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Three-dimensional MPP and permeable membrane space sound absorbers: An overview

    SAKAGAMI KIMIHIRO, OKUZONO TAKESHI, YAIRI MOTOKI, TOYODA MASAHIRO

    WESPAC, 2015年12月, Proceedings of 12th WESPAC, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • A comparison of absorption models of microperforated panel absorbers on room acoustics simulations using finite element method

    OKUZONO Takeshi, SAKAGAMI Kimihiro

    2015年12月, Proc of 12th Wespac, No.O4000037, 63 - 66, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • On the relationship between the normal incidence airborne sound-excited and the structurally-excited sound radiation from a wall: A theoretical trial with simplified models

    YAIRI MOTOKI, SAKAGAMI KIMIHIRO, NISHIBARA KOSUKE, OKUZONO TAKESHI

    Multi-Science Publishing, 2015年10月, Journal of Building Acoustics, 22 (2), 109 - 122, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takuya Oshima, Yasuhiro Hiraguri, Takeshi Okuzono

    Knowledge of distinct effects of moisture content and air volume on acoustic properties of soil is sought to predict the influence of human activities such as cultivation on acoustic propagation outdoors. This work used an impedance tube with the two-thickness method to investigate such effects. For a constant moisture weight percentage, the magnitude of the characteristic impedance became smaller and the absorption coefficient became higher with increase of the air space ratio. For a constant air space ratio, the absorption coefficient became larger and the magnitude of the propagation constant became smaller with increasing moisture weight percentage. (C) 2015 Acoustical Society of America

    ACOUSTICAL SOC AMER AMER INST PHYSICS, 2015年09月, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 138 (3), EL258 - EL263, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Kimihiro Sakagami

    A simple frequency-domain finite-element method (FD-FEM) for sound field analyses inside rooms installed with microperforated panel (MPP) sound absorbing structures is described here. This method can also analyze sound absorbing structures composed of MPPs and permeable membranes (PM) simply by changing the only material parameters of MPP into those of PM. As the first stage of the study, the validity of the present FD-FEM is tested through the numerical experiments based on the impedance tube method for measuring the absorption characteristics at normal incidence. In the numerical experiments, we calculated the absorption characteristics of a single MPP absorber, a double-leaf MPP space absorber and a space absorber composed of MPP and PM by using the FD-FEM in two-dimensions, and the computed absorption characteristics are compared with those calculated by an electro-acoustical equivalent circuit theory or a wave theory based on Helmholtz-Kirchhoff boundary integral equation. The results showed that the presented FD-FEM can analyze the absorption characteristics at normal incidence of the MPP sound absorbing structures accurately with the simplicity of the formulation. (C) 2015 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2015年08月, APPLIED ACOUSTICS, 95, 20 - 26, 英語

    [査読有り]

    研究論文(学術雑誌)

  • 通気性単一膜を用いた矩形平面状空間吸音体の残響室法吸音率測定

    杣友 祐, 奥園 健, 舟橋 康太, 阪上 公博, 豊田 政弘

    日本音響学会, 2015年06月, 日本音響学会誌, 71 (6), 276 - 277, 日本語

    [査読有り]

    研究論文(学術雑誌)

  • An experimental study on the absorption characteristics of a three-dimensional permeable membrane space sound absorber

    Kimihiro Sakagami, Kota Funahashi, Yu Somatomo, Takeshi Okuzono, Chinami Nishikawa, Masahiro Toyoda

    In this study, we propose a rectangular and cylindrical three-dimensional space sound absorber using a permeable membrane and the absorption characteristics which are examined experimentally by reverberation room method. As a pilot study, a two-dimensional boundary element (2-D BEM) analysis is also conducted to predict the absorption characteristics of the absorbers. The experimental study revealed that the absorption coefficient is low at low frequencies and gradually increases with frequency. The absorption coefficient converges to 0.5 at the maximum which is similar to a single-leaf permeable membrane. The flow resistance and the surface density of the permeable membrane mainly affect the absorption characteristics at middle to high frequencies. At low frequencies, the heavy membrane contributes to the higher absorption performance. In the experiment specimens with high flow resistance produce higher absorptivity. Also, the cylindrical absorber shows slightly higher absorption coefficient than the rectangular absorber mainly at low frequencies. The 2-D BEM results show similar frequency characteristics as the measured values when the membrane's flow resistance and surface density are low, but the numerical values overestimate overall the absorptivity of the absorbers. (C) 2015 Institute of Noise Control Engineering.

    INST NOISE CONTROL ENGINEERING, 2015年05月, NOISE CONTROL ENGINEERING JOURNAL, 63 (3), 300 - 307, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Kimihiro Sakagami

    The authors proposed a simple finite element (FE) formulation in order to predict sound fields in rooms with microperforated panel (MPP) absorbers, and its validity was also presented through comparisons with electro acoustical equivalent circuit theory and wave theory in numerical experiments based on an impedance tube method. A 2D room acoustics simulation with a single-leaf MPP absorber is performed, in which a surface impedance model based on a locally reactive assumption is also used for comparison. This model uses the normal-incidence normalized acoustic impedance on the surface of the MPP absorber under an impedance boundary condition based on the locally reactive assumption that neglects the incident-angle dependence of the normalized acoustic impedance. The results are compared with results obtained without the single-leaf MPP absorber in the 1/3-octave-band mean sound pressure level (SPL) and in the 1/3-octave-band SPL distribution. From the results, it is expected that the reduction effect of the SPL after installing the single-leaf MPP absorber will be overestimated overall when using the surface impedance model.

    Acoustical Society of Japan, 2015年, Acoustical Science and Technology, 36 (4), 358 - 361, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Takeshi Okuzono, Toru Otsuru, Kimihiro Sakagami

    The accuracy and efficiency of the explicit time-domain finite-element method (TD-FEM) was studied with the dissipation term on room acoustics simulation at high frequencies through a numerical comparison with the implicit TD-FEM for large-scale analysis. Sound fields inside the cubic cavity with finite impedance boundaries were computed to reveal the effect of the use of the backward difference in the dissipation term of the explicit method on the resulting accuracy in analysis at high frequencies. Computed sound pressures were compared with the reference solution obtained using the implicit method. In the computations, the time interval of the explicit method was again determined by the stability condition of the implicit method and was set to near the critical value. It can be said that this method is very useful for room acoustics simulation, in which the room shape can be approximated by cubic FEs. The applicability of the explicit method for more generalized cases using rectangular FEs and distorted FEs will be presented in the future, as well as derivations of dispersion relation and stability condition for three-dimensional analysis.

    Acoustical Society of Japan, 2015年, Acoustical Science and Technology, 36 (4), 377 - 380, 英語

    [査読有り]

    研究論文(学術雑誌)

  • A SIMPLE FREQUENCY DOMAIN FINITE-ELEMENT FORMULATION FOR PREDICTING ABSORPTION CHARACTERISTICS OF MICROPERFORATED PANEL ABSORBERS

    Takeshi Okuzono, Kimihiro Sakagami

    Sound-absorbing materials play an important role in the control of acoustics in built environments. Recently, the concept of sustainable acoustical materials is becoming important in the development of sound-absorbing materials. Microperforated panels (MPP) that can be made from any recyclable materials are one of such materials. Various MPP absorbers and prediction methods of their absorption characteristics have been proposed. Wave-based numerical methods such as the finite-element method (FEM) are one of the powerful tools to design MPP absorbers. In this paper, first, we present a simple and computationally-efficient frequency-domain FEM for predicting absorption characteristics of MPP absorbers, in which only two material parameters, MPP's acoustic impedance determined by Maa's theory and MPP's surface density, are used. Then, the effectiveness of the present FEM is tested through numerical experiments based on an impedance tube method for measuring sound absorption characteristics at normal incidence. In the numerical experiments, we calculated absorption characteristics of a single MPP absorber, a double-leaf MPP space absorber, and a space absorber composed of MPP and permeable membranes (PM), respectively, using the FEM. The results calculated using the FEM are verified by comparison with absorption characteristics calculated using electro-acoustical equivalent circuit theory and wave theory based on Helmholtz-Kirchhoff boundary integral equation. The numerical experiments revealed that the present FEM can be analyzed normal incidence sound absorption characteristics of MPP absorbers composed of MPP and PM, accurately, within the application range of the formulation.

    INT INST ACOUSTICS & VIBRATION, 2015年, PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION, 1 - 8, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • Finite element sound field analysis for correction of absorption coefficient in reverberation room

    TOMIKU Reiji, OTSURU Toru, OKAMOTO Noriko, OKUZONO Takeshi, AZECHI Yoshiki, YOSHIDA Tsuyoshi

    In this study, sound fields for the measurement of sound absorption coefficient by reverberation room method are analyzed by time domain finite element method. This study shows effectiveness of the analysis for investigation on causes of variation in the measurement results and improvement methods of the measurement. To evaluate an actual sound field for the measurement, the ratio of incident sound energy to the test material in those to all boundary of the measurement sound field is calculated from results of the finite element sound fields analysis. First, square sound pressure amplitudes of plane sound wave incident on absorption material are calculated in one-dimensional sound field. Next, the calculation method of the ratio of the measurement sound field is described. Finally, relationship among the ratio, shape of the measurement room, and characteristics of the test material is investigated, and it is shown that the bigger normal incident sound absorption coefficient of test material, the larger the change of the ratio for decay sound field regardless of room shape and surface area of test material.

    2014年11月, CD-ROM Proceedings of inter.noise 2014, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Application of an in-situ measurement method using ensemble averaging technique to material development

    OKAMOTO Noriko, OTSURU Toru, TOMIKU Reiji, KAMIMIZU Takaaki, YAMAGUCHI Makoto, OKUZONO Takeshi

    2014年11月, CD-ROM Proceedings of inter.noise 2014, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • An explicit time-domain finite-element method for room acoustics simulation

    OKUZONO Takeshi, OTSURU Toru, SAKAGAMI Kimihiro

    2014年11月, CD-ROM Proceedings of inter.noise 2014, 英語

    [査読有り][招待有り]

    研究論文(国際会議プロシーディングス)

  • Absorption modeling with ensemble averaged impedance for wave-based room acoustics simulations

    OTSURU Toru, TOMIKU Reiji, OKUZONO Takeshi

    2014年11月, CD-ROM Proceedings of inter.noise 2014, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Takeshi Okuzono, Toru Otsuru, Reiji Tomiku, Noriko Okamoto

    This paper presents a finite element method (FEM) using hexahedral 27-node spline acoustic elements (Sp127) with low numerical dispersion for room acoustics simulation in both the frequency and time domains, especially at higher frequencies. Dispersion error analysis in one dimension is performed to increase the accuracy of FEM using Sp127 by modifying the numerical integration points of element stiffness and mass matrices. The basic accuracy and efficiency of the FEM using the improved Sp127, which uses modified integration points, are presented through numerical experiments using benchmark problems in both the frequency and time domains, revealing that FEM using the improved Sp127 in both domains provides more accurate results than the conventional method does, and with fewer degrees of freedom. Moreover, the effectiveness of FEM using the improved Sp127 over that using hexahedral 27-node Lagrange elements is shown for time domain analysis of the sound field in a practical sized room. (C) 2013 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2014年05月, APPLIED ACOUSTICS, 79, 1 - 8, 英語

    [査読有り]

    研究論文(学術雑誌)

  • 舟橋 康太, 杣友 祐, 西川 智菜美, 阪上 公博, 奥園 健, 豊田 政弘

    神戸大学大学院工学研究科, 2014年, 神戸大学大学院工学研究科・システム情報学研究科紀要, 6 (6), 17 - 23, 日本語

    [査読有り]

    研究論文(大学,研究機関等紀要)

  • Toru Otsuru, Takeshi Okuzono, Noriko Okamoto, Yusuke Naka

    Finite element method (FEM) is widely used in various engineering fields to solve problems with too many complexities to be dealt with by certain conventional approaches. In 1943, Courant proposed the theoretical basis of the method, and, in 1956, Turner et al. published both fundamental theory and application of FEM, namely "Stiffness deflection analysis", to solve structural problems [1, 2]. A decade and several years latter, FEM has been come to be applied to solve various acoustic problems [3-5]. Compared with other numerical techniques, FEM is advantageous in its broad range of applicability. However, FEM requires discretization of the domain, which results in huge amount of degrees-of-freedom especially when a three-dimensional domain is analyzed. Nevertheless, the matrices constructed in a standard FEM procedure have rather simple mathematical structures with sparseness. The simplicity makes their computationmore efficient especially when they are processed on a parallel/vector processors. Generally speaking, the iterative methods are suitable for solving such a sparse matrix equation efficiently with far lessmemory space on a computer. In this chapter, fundamentals, improvements, and applications of FEM on acoustic problems are explored.

    Springer Japan, 2013年11月01日, Computational Simulation in Architectural and Environmental Acoustics: Methods and Applications of Wave-Based Computation, 9784431544548, 53 - 78, 英語

    [査読有り]

    論文集(書籍)内論文

  • Takeshi Okuzono, Toru Otsuru, Reiji Tomiku, Noriko Okamoto

    A study was conducted to demonstrate the use of dispersion-reduced spline (Spl27) acoustic finite elements for frequency-domain analysis. It was demonstrated that Spl27 used the natural cubic spline polynomial of degree 3 to construct the shape function. The shape function in three dimensions for Spl27 was defined by using the natural cubic spline polynomial. The resulting dispersion relation was used to design an improved Spl27 with low dispersion. A finite-element mesh consisting of three-node spline line elements of nodal distance d was also considered to conduct the investigations. The proposed method modified the numerical integration points of element stiffness matrix and mass matrix, while the integration points were calculated from a condition that minimizes the dispersion error at an arbitrary non-dimensional wave number on an one-dimensional mesh.

    2013年, Acoustical Science and Technology, 34 (3), 221 - 224, 英語

    [査読有り]

    研究論文(学術雑誌)

  • M. N. Yahya, T. Otsuru, R. Tomiku, T. Okuzono

    Various prediction techniques of reverberation time such as the Sabine and Eyring equations, ray-method, and numerical method require main parameters such as the absorption coefficient and dimensions. Normally, these parameters are obtained from references or/and measurements that necessitate special equipment and skills. On that matter, the authors have proposed a new practical technique to identify the absorption coefficient and dimensions of rooms. The technique comprises Subsystem_1 and Subsystem_2, each of which uses photographic images. Subsystem_1 uses a Gray Level Co-occurrence Matrix (GLCM) and is integrated with a Neural Network (NN) to identify the absorption coefficient of the material. Subsystem_2 uses a Dimension Vision Predictor (DVP) with the author's "ruler method" to identify the dimensions. Examinations conducted in practical rooms revealed a good correlation coefficient of r ≥ 0.90 for Subsystem_1 and r ≥ 0.99 for Subsystem_2. Finally, the System using NN gave inconsistent results, while FEA revealed consistent results with r ≥0.8. © Universiti Malaysia Pahang.

    Universiti Malaysia Pahang, 2013年, International Journal of Automotive and Mechanical Engineering, 8 (1), 1256 - 1266, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Relationship between dispersion error and accuracy of room acoustics parameter in time-domain finite-element room acoustics simulation

    OKUZONO Takeshi, OTSURU Toru, TOMIKU Reiji, OKAMOTO Noriko

    The time-domain finite-element method (TD-FEM) is a powerful wave-based numerical method for room acoustics simulation. However, it is well known that this method incurs an inherent error, called dispersion error, due to both spatial and time discretizations. To obtain a reliable result, discretization of both space and time, which maintain the dispersion error within acceptable level, is required, although the level for room acoustics applications such as calculating of the room acoustical parameters still remains unclear. Further, sufficiently fine spatial and time discretizations for reducing the error make the computation expensive. For efficient use of the method in practical applications, the balance between accuracy and computational cost needs to be considered. For the purpose, this paper presents the relationships between the dispersion errors and accuracy of room acoustical parameters in TD-FE analysis with fourth-order accuracy. Five room acoustical parameters of a sound field in a rectangular room with volume of 62 m3 were computed at frequencies from 250 Hz to 1 kHz, using TD-FEM with FE meshes of different spatial resolutions and with different time resolutions. Also, the dispersion errors in each analysis were theoretically estimated by dispersion error analysis in three dimensions. Results showed that the use of FE meshes having dispersion error below 0.52 % is recommended to yield the reasonable results at given frequency range.

    2013年, CD-ROM Proceedings of Inter-Noise 2013, 2, 1300 - 1307, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Humidity effect on pressure-velocity sensor examined in sound absorption measurement with ensemble averaging technique

    OTSURU Toru, KUSNO Asniawaty, TOMIKU Reiji, OKUZONO Takeshi, OKAMOTO Noriko, NAZLI Bin Che Din

    2013年, CD-ROM Proceedings of Inter-Noise 2013, 英語

    [査読有り]

    研究論文(国際会議プロシーディングス)

  • Takeshi Okuzono, Toru Otsuru, Reiji Tomiku, Noriko Okamoto

    The applicability of the modified integration rule for time-domain finite-element analysis is tested in sound field analysis of rooms involving rectangular elements, distorted elements, and finite impedance boundary conditions. Dispersion error analysis in three dimensions is conducted to evaluate the dispersion error in time-domain finite-element analysis using eight-node hexahedral elements. The results of analysis confirmed that fourth-order accuracy with respect to dispersion error is obtainable using the Fox-Goodwin method (FG) with a modified integration rule, even for rectangular elements. The stability condition in three-dimensional analysis using the modified integration rule is also presented. Numerical experiments demonstrate that FG with a modified integration rule performs much better than FG with the conventional integration rule for problems with rectangular elements, distorted elements, and with finite impedance boundary conditions. Further, as another advantage, numerical results revealed that the use of modified integration rule engenders faster convergence of the iterative solver than a conventional rule for problems with the same degrees of freedom. (C) 2012 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4730920]

    ACOUSTICAL SOC AMER AMER INST PHYSICS, 2012年08月, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, 132 (2), 804 - 813, 英語

    [査読有り]

    研究論文(学術雑誌)

  • ムスリ ニザム ビン ヤハヤ, 大鶴 徹, 富来 礼次, 奥園 健, 長澤 利喜, 小田 智弘

    A practical technique for simulating room acoustics parameters is proposed. The technique comprises Subsystems 1 and 2, each of which uses photographic images. Subsystem 1 uses a Gray Level Cooccurrence Matrix and a Feed Forward Neural Network to identify material surfaces. Subsystem 2 uses a Dimension Vision Predictor with the author's "ruler method" to identify the dimensions. Examinations conducted in practical rooms revealed good correlation coefficients of r ≥ 0.90 for Subsystem 1 and r ≥ 0.99 for Subsystem 2. Finally, simulations of reverberation times were conducted using Finite Element Analysis (FEA) with identified parameters. Sufficient agreement was confirmed.

    2012年, 日本建築学会技術報告集, 18 (39), 601 - 606, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Finite element sound field analysis in a reverberation room using ensemble averaged surface normal impedance

    Reiji Tomiku, Toru Otsuru, Noriko Okamoto, Takeshi Okuzono, Takahiro Shibata

    The purpose of this paper is to indicate the effectiveness of an ensemble averaged surface normal impedance, which are measured by the authors' proposed method: EA method, as an boundary condition of the sound field analysis by wave-based numerical methods. Firstly, sound fields in an irregularly shaped reverberation room with glass wool located on floor are analyzed by time domain finite element method (TDFEM). In those analyses, two types of surface normal impedance, i.e. the ensemble averaged surface normal impedance at random incidence and surface normal impedance at normal incidence, are considered as a boundary condition of the glass wool. Then, impulse responses and decay curves of the sound field obtained by the TDFEM are compared with those obtained by the measurements. The results using the ensemble averaged surface normal impedance show better agreement with measured values than those using the surface normal impedance at normal incidence. Copyright © (2011) by the Institute of Noise Control Engineering.

    2011年, 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011, 2, 1475 - 1480

    研究論文(国際会議プロシーディングス)

  • Takeshi Okuzono, Toru Otsuru, Reiji Tomiku, Noriko Okamoto

    This paper presents an assessment of the accuracy and applicability of a time domain finite element method (TDFEM) for sound-field analysis in architectural space. This TDFEM incorporates several techniques: (1) a hexahedral 27-node isoparametric acoustic element using a spline function; (2) a lumped acoustic dissipation matrix; and (3) Newmark time integration method with an absolute diagonal scaled COCG iterative solver. Sound fields in an irregularly shaped reverberation room of 166 m(3) are computed using TDFEM. The computed values and measured values for 125-500 Hz are compared, revealing that the fine structure of the computed band-limited impulse responses agree with measured ones up to 0.1 s, with a cross-correlation coefficient greater than 0.93. The cross-correlation coefficient decreases gradually over time, and more rapidly for higher frequencies. Moreover, the computed decay curves, and the reverberation times, agree well with the respective measured ones, and with a better fit the higher the frequency (up to 500 Hz). (C) 2010 Elsevier Ltd. All rights reserved.

    ELSEVIER SCI LTD, 2010年10月, APPLIED ACOUSTICS, 71 (10), 940 - 946, 英語

    [査読有り]

    研究論文(学術雑誌)

  • Accuracy and efficiency of time domain finite element method for sound field analysis of rooms

    Takeshi Okuzono, Toru Otsuru, Reiji Tomiku, Noriko Okamoto

    Various numerical methods based on the wave equation have been developed and utilized in many fields on acoustics. Due to high computational cost, it is still not easy for a method like the finite element method (FEM) to compute a room impulse response up to high frequency region if the room has rather a big volume like a music hall. To efficiently predict the sound field, the authors have been developing a system of large-scale finite element sound field analysis (LsFE-SFA) both in the time and the frequency domains. In this paper, accuracy and efficiency of a time domain FEM (TDFEM) are investigated. Sound pressure waveforms in a cubic room with the volume of 64 m3 are computed both by the TDFEM and time domain finite difference method (TDFDM), and the results are compared to reveal the effects of both spatial and time resolutions. The results show that TDFEM requires less computational cost than that of TDFDM. Next, frequency response in an office room with the volume of 70 m3 is computed by TDFEM and frequency domain FEM (FDFEM), and the results show that the agreement between the two methods is excellent. Moreover, calculation of frequency response by the TDFEM is effective when slow convergence of iterative method applied on FDFEM is preliminarily expected for a given sound field.

    2009年, 38th International Congress and Exposition on Noise Control Engineering 2009, INTER-NOISE 2009, 6, 4344 - 4352

    研究論文(国際会議プロシーディングス)

  • 奥園 健, 大鶴 徹, 岡本 則子, 富来 礼次

    An iterative method is applied to time domain finite element method (TDFEM) to reduce the computational cost. First, eigenvalues distributions of coefficient matrix A] of linear systems [A]{x} = {b} arise in TDFEM are calculated to reveal the matrix property for basic sound field analysis. Then, convergence behaviors of preconditioned COCG method are shown for practical sound field analyses. Results show that [A] of [A]{x} = {b} arise in TDFEM has good property, which leads fast convergence of preconditioned COCG method, and the method converges with about 20 iterations per time step regardless of sound field and degrees of freedom if convergence criterion be set to 10-6.

    2008年06月, 日本建築学会環境系論文集, 73 (628), 701 - 706, 日本語

    [査読有り]

    研究論文(学術雑誌)

  • Kimihiro Sakagami, Midori Kusaka, Takeshi Okuzono

    Recently, dotted-art MPPs have been proposed in which a designed pattern is made with the holes. In such a case, the MPP becomes heterogeneous in general. However, existing theories used for the prediction of the absorption characteristics of MPPs assume homogeneity. Therefore, the elaboration of a method for heterogeneous MPPs needs to be performed. In previous work, the authors proposed a method to predict the absorption characteristics of a heterogeneous MPP by using synthesized impedances of each part with different parameters; this is called the synthetic impedance method (SIM) in the present paper. The SIM can potentially be used for various heterogeneous MPPs; however, its scope of applicability needs to be clarified. Furthermore, in proposing a design concept of dotted-art heterogeneous MPPs, the condition that would make the designed MPPs fall within the scope of the SIM needs to be determined. Therefore, in this study, in order to clarify the scope of the applicability of the SIM, twelve samples are first prepared, and then measured sound absorption characteristics and predicted ones are compared and examined in terms of prediction errors. The results show that there are two conditions that should be met to produce predictable heterogeneous MPPs: (1) holes are distributed over the entire surface of the specimen, and (2) the hole spacing is constant. Considering these conditions, a design concept for a dotted-art heterogeneous MPP is proposed: two types of holes, larger holes for the pattern and smaller holes for the background, should be used to meet the above two conditions. Case studies with nine prototypes show that the SIM can make predictions for dotted-art heterogeneous MPPs fabricated according to the concept described above.

    MDPI AG, 2022年07月31日, Acoustics, 4 (3), 588 - 608

    研究論文(学術雑誌)

  • 岡本 則子, 大鶴 徹, 奥園 健

    九州大学情報基盤センター, 2007年03月, 九州大学情報基盤センター広報 : 全国共同利用版, 6 (3), 182 - 184, 日本語

  • 奥園 健, 大鶴 徹, 岡本 則子

    九州大学情報基盤センター, 2007年03月, 九州大学情報基盤センター広報 : 全国共同利用版, 6 (3), 185 - 187, 日本語

  • Marie Mimura, Takeshi Okuzono, Kimihiro Sakagami

    This paper presents discussion of the prediction capability of three numerical models using finite element method for predicting the sound reduction index (SRI) of fixed windows having different dimensions in a laboratory environment. The three numerical models tested here only discretize the window part or windows part and the space around the windows to reduce the necessary computational cost for vibroacoustics simulations. An ideal diffused sound incidence condition is assumed for three models. Their predictability and numerical efficiency were examined over five fixed windows with different dimensions compared to measured SRIs. First, the accuracy of the simplest model in which the window part is only discretized with finite elements was examined. Acoustic radiation to the transmission field is computed using Rayleigh’s integral. Calculations were performed under two loss factor setups respectively using internal loss factors of each material and measured total loss factor of each window. The results were then compared with the measured values. Results revealed the effectiveness of using the measured total loss factor at frequencies around and above the coincidence frequencies. Subsequently, we tested the prediction accuracy of a numerical model that includes a niche existing in a laboratory environment. Also, hemispherical free fields around the window are discretized using fluid elements and infinite fluid elements. The results underscored the importance of including a niche in a numerical model used to predict sound reduction index below 1 kHz for smaller windows accurately. Nevertheless, this numerical model, including a niche, entails high computational costs. To enhance the prediction efficiency, we examined the applicability of a weak-coupling model that divides calculation procedures into three steps: (1) incidence field calculation to the window surface, (2) sound transmission calculation in fixed windows, and (3) sound radiation calculation from a window surface to a transmission field. Results revealed that the weak-coupling model produces almost identical results to those of a strong-coupling model, but with higher efficiency.

    Frontiers Media SA, 2022年08月29日, Frontiers in Built Environment, 8, 971459, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

  • Marie Mimura, Yohei Tsukamoto, Yoshihiro Tomikawa, Takeshi Okuzono, Kimihiro Sakagami

    Acoustical Society of Japan, 2022年09月01日, Acoustical Science and Technology, 43 (5), 276 - 279, 英語, 国際誌, 国際共著していない

    [査読有り]

    研究論文(学術雑誌)

MISC

  • 音響数値シミュレーションのシーズ

    奥園健, 吉田卓彌, 阪上公博

    2022年03月, 第81回音シンポジウム資料 建築音響測定への数値シミュレーションの活用とその可能性, 49 - 56, 日本語, 国際共著していない

    講演資料等(セミナー,チュートリアル,講習,講義他)

  • 奥園 健

    2022年02月, 日本音響学会誌, 78 (2), 73 - 80, 日本語, 国内誌, 国際共著していない

    記事・総説・解説・論説等(学術雑誌)

  • 背後ハニカム構造を有するMPP吸音体の実装実験

    阪上 公博, 矢入 幹記, 奥園 健, 羽入 敏樹, 星 和磨, 原田 慎史, 高橋 誠治, 上田 泰孝

    日本音響材料協会, 2017年06月, 音響技術, 46 (178), 58 - 62, 日本語

    速報,短報,研究ノート等(学術雑誌)

  • 奥園健, 大鶴徹, 富来礼次, 岡本則子, 巳之口俊史

    九州大学情報統括本部広報委員会, 2009年10月, 九州大学情報基盤研究開発センター全国共同利用システム広報, 3 (1), 24 - 27, 日本語

    記事・総説・解説・論説等(大学・研究所紀要)

書籍等出版物

  • 分担執筆, 第3章、第8章8.1を担当, 日本建築学会, 2021年12月, 日本語, 国際共著していない, ISBN: 9784818926714

    [査読有り]

  • Computational Simulation in Architectural and Environmental Acoustics-Methods and Applications of Wave-Based Computation-

    OKUZONO Takeshi, ASAKURA Takumi, HORINOUCHI Yoshinari, HOSHI Kazuma, INOUE Naohisa, ISHIZUKA Takashi, KAWAI Yasuhito, MASUMOTO Takayuki, NAKA Yusuke, OKAMOTO Noriko, OKUBO Kan, OKUBO Tomonao, ONITSUKA Hirofumi, OSHIMA Takuya, OTSURU Toru, SAKAMOTO Shinichi, SAKUMA Tetsuya, SUZUKI Hisaharu, TOMIKU Reiji, TOYODA Masahiro, TSURU Hideo, YASUDA Yosuke, YOKOTA Takatoshi

    共著, Springer, 2014年08月, 英語, ISBN: 9784431544531

    学術書

  • 音環境の数値シミュレーションー波動音響解析の技法と応用

    日本建築学会

    共著, 2011年10月, 日本語, ISBN: 4818927074

講演・口頭発表等

  • 波動音響解析に基づく室内音響データベース構築に関する基礎検討―会議室を対象とした吸音効果の可聴化―

    奥園健, 吉田卓彌, 阪上公博

    日本音響学会建築音響研究委員会, 2021年09月28日, 日本語, 建築空間の用途に応じた快適な音環境の形成には、吸音材を適切に使 用した室内音響調整が必要である。しかし、吸音設計が不適切なため音環境に問題 のある建築空間がいまだに数多く存在している。この一因として、建築音響の非専門家には吸音による音環境調整の重要性が十分に理解されていないことが考えられる。本研究では、この現状を解決する一つの策として、様々な建築空間における多 様な吸音材の効果を聴感的に体験することを可能とする室内音響データベースの作成を考えた。本稿ではその端緒として、小会議室を対象に実施した基礎検討の結果を報告する。具体的には、代表的な多孔質吸音材であるグラスウールとカーテンに焦点をあて、時間領域の波動音響シミュレーションのひとつである時間領域有限要素法を用いて、いくつかの内装条件における室内インパルス応答を音響材料の周波数依存性と入射角依存性を考慮して計算し、吸音による室内音響調整の効果を聴き比べることができるコンテンツの作成を試みた。, 国内会議, 国際共著していない

    口頭発表(一般)

  • 時間領域 FEM による周波数依存の吸音境界を含む室内音場解析–周波数領域 FEM との比較–

    奥園健, 吉田卓彌, 阪上公博

    日本音響学会建築音響研究委員会, 2021年03月29日, 日本語, 波動音響解析による高精度な室内音場予測のためには,材料の吸音特性の周波数依存性を考慮した吸音境界条件の使用が不可欠である。しかし,時間領域 における吸音境界条件には畳み込みが含まれることから,効率的な実装が必要となる。本論文では,補助微分方程式法を用いて吸音境界の周波数依存性を考慮した陰的時間領域FEMの性能を周波数依存性を厳密に反映可能な周波数領域FEMとの比較から明らかにする。音響管問題による時間領域FEMがもつ離散化誤差特性の検証から,時間領域FEMの離散化誤差の大きさは多孔質材の流れ抵抗率に依存し,その収束率は周波数領域 FEMと同様の2に近似すること,時間刻み幅を小さくす るにつれ周波数領域FEMの結果へと収束すること,を明らかにする。さらに実大の2次元オフィス,コンサートホールモデルを用いて,時間領域FEMは周波数領域FEMと同等の精度の解析を約 7 倍 ∼18 倍高速に計算できることを示す。

    口頭発表(一般)

  • Partition of Unity FEM による 3 次元室内音場解析に関する基礎的研究

    田丸加奈子, 奥園健, 向江俊一, 阪上公博

    日本音響学会春季研究発表会, 2021年03月10日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 単板ガラス窓の遮音性能の実用的予測式の構築(2)

    玉井芳, 阪上公博, 奥園健, 塚本陽平

    日本音響学会春季研究発表会, 2021年03月10日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 単板ガラス窓の遮音性能の実用的予測式の構築(1)

    塚本陽平, 玉井芳, 阪上公博, 奥園健

    日本音響学会春季研究発表会, 2021年03月10日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 単窓の遮音性能の実用的予測に関する基礎的検討-単板ガラスの場合-

    塚本陽平, 阪上公博, 奥園健, 富川義弘

    日本音響学会建築音響研究委員会, 2020年07月16日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 製作精度によるパラメタのばらつきがMPPの吸音特性に及ぼす影響-3Dプリンタによる各種MPP吸音体作成の試み-

    阪上公博, 草鹿みどり, 奥園健, 中西伸介

    日本音響学会建築音響研究委員会, 2020年06月17日, 日本語, 本研究では,3D プリンタによって作成したMPP の製作精度が,MPP の吸音特性に及ぼす影響について,実験および理論の両面から 基礎的な検討を行った.MPP については,従来に比べてコストの低廉化や工程の簡略化に向けて,近年は多種多様な試作事例が報告されており,3D プリンタによる試作検討事例も報告されている.こうした場合,一般的な穴あけ加工以外の手法では,その製作精度が問題となる場合も多いが,その影響について詳しい考察を行った研究例はごく少数である.本研究では,民生用に広く普及している熱溶解積層型3D プリンタによって各種形態のMPP の作成を試み,その精度について検討し,誤差が音響特性および理論による予測精度に及ぼす影響について,基礎的な考察を試みた.その結果,熱溶解積層型3D プリンタによるMPP 作成は精度的には誤差が大きいものの,一定の吸音性能を示すが,理論値との一致は悪いため設計や予測の際には注意を要することを論じた., 国内会議, 国際共著していない

    口頭発表(一般)

  • 時間領域FEM による通気性膜吸音体の残響室法吸音率の数値予測

    奥園健, 阪上公博

    日本音響学会建築音響研究委員会, 2020年05月28日, 日本語, 通気性膜(各種天然・化学繊維素材の通気性のある薄い織編物・不織布)は繊維・製造方法・加工技術の組み合わせで様々な機能設計が可能な魅力的な吸音材料であり、近年、様々な通気性膜吸音体が開発され室内の音響調整に活用されている。本稿では、著者らの先行研究に基づき通気性膜を時間領域FEM解析でモデル化する方法を提示するとともに、残響室法吸音率の測定を直接的に時間領域で模擬し、最も古典的な単一通気性膜吸音体を対象として数値解析値を実測値ならびに理論値と比較した結果を示す。汎用繊維であるPET, PP, ガラス繊維素材の材料特性の異なる8 種類の通気性膜について検討し、結果として、提示した時間領域解析手法により、通気性膜の材料特性の違いによる残響室法吸音率の大小関係を予測できることを示す。, 国際会議, 国際共著していない

    口頭発表(一般)

  • 平面波エンリッチメントを用いたPartition of Unity FEMによる室内音場解析 その2−低次要素と高次要素の比較−

    向江俊一, 奥園健, 田丸加奈子, 阪上公博

    日本音響学会2020年春季研究発表会, 2020年03月16日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 平面波エンリッチメントを用いたPartition of Unity FEMによる室内音場解析

    奥園健, 田丸加奈子, 向江俊一, 阪上公博

    日本音響学会建築音響研究委員会, 2020年01月14日, 日本語, Helmholtz方程式の一般解を用いて場の近似を強化し、Q-refinementによって粗いメッシュを用いて高周波数まで解析を行うPartition of Unity FEM(PUFEM)に基づく音響数値解析手法を室内音場解析手法に導入する。まず一般解として平面波をエンリッチメントに用いるPUFEMの基礎理論を示す。次に2種の2次元室内音場を対象に、空間4次精度のFEMを参照解として、従来の空間2次精度FEMとの比較からPUFEMの精度ならびにQ-refinementの有用性を明らかにする。結果として、PUFEMは単一の粗いメッシュを用いて、従来FEMに比べ、少なくともオーダー1/100以下の著しく少ない自由度で広帯域の周波数応答をより高精度に計算できることを示す。

    口頭発表(一般)

  • 室内音響指標予測精度改善に関する数値解析的研究

    吉田 剛, 大鶴 徹, 富来 礼次, 奥園 健, 畔地 良樹

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2015年03月, 日本語, 一般社団法人日本建築学会

  • 残響室法吸音率の測定に関する数値解析的研究 : 残響時間のばらつきに関する検討

    畔地 良樹, 大鶴 徹, 富来 礼次, OKAMOTO Noriko, 奥園 健, 吉田 剛

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2015年03月, 日本語, 一般社団法人日本建築学会

  • 40130 アンサンブル平均を利用した材料の吸音特性のin-situ測定に関する研究 : その1 音響管を用いた音圧-粒子速度センサの校正(吸音,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    上田 笑, 大鶴 徹, 富来 礼次, 奥園 健, 柳池 将俊

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40122 室内音場解析の室形状モデリングに関する研究 : 時間領域有限要素法を用いた部材の奥行きの簡略化の検討(数値解析,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    松本 史, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 星 和磨, 板井 健

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40125 残響室法吸音率の測定に関する数値解析的研究 : 吸音率の測定誤差および残響時間のばらつきの検討(数値解析,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    畔地 良樹, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 吉田 剛

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40124 時間領域有限要素法による残響室法吸音率の測定精度改善に関する研究 : 試料への音の入射エネルギの割合に着目した音場の分類(数値解析,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    吉田 剛, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 畔地 良樹

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40132 アンサブル平均を利用したin-situ吸音測定法の応用 : 天井改修による実在カフェ空間の音響改善(吸音,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    中村 麻美, 大鶴 徹, 富来 礼次, 奥園 健

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40131 アンサンブル平均を利用した建築材料の吸音特性のin-situ測定に関する研究 : その2 Piston on a sphere法による音圧-粒子速度センサの校正(吸音,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    柳池 将俊, 大鶴 徹, 富来 礼次, 奥園 健, 上田 笑

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40123 時間領域有限要素法を用いた波動音響シミュレーションの室形状モデリングに関する研究 : その4 音響要素による差異(数値解析,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    板井 健, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 松本 史

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40085 砂質土の音響特性に対する気液相比率の影響に関する基礎的研究(騒音伝搬,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    大嶋 拓也, 奥園 健, 平栗 靖浩

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 40086 地表面の実測吸音特性と航空ハイパースペクトル画像による分光放射輝度の対応に関する基礎的研究(騒音伝搬,環境工学I,2014年度日本建築学会大会(近畿)学術講演会・建築デザイン発表会)

    若松 慶, 大嶋 拓也, 平栗 靖浩, 奥園 健, 富来 礼次, 岡本 則子, 大鶴 徹

    学術講演梗概集, 2014年09月12日, 日本語, 一般社団法人日本建築学会

  • 4-3-c 地表面の実測吸音特性と航空ハイパースペクトルカメラによる分光放射輝度の関連に関する基礎的検討(環境系)

    若松 慶, 富来 礼次, 大嶋 拓也, 岡本 則子, 平栗 靖浩, 大鶴 徹, 奥園 健

    日本建築学会北陸支部研究報告集, 2014年07月13日, 日本語, 一般社団法人日本建築学会

  • 414 カフェの音環境改善に関する基礎的研究 : 音響改修効果と測定吸音率に関する検討(環境工学)

    松島 梨花子, 大鶴 徹, 富来 礼次, 奥園 健

    日本建築学会研究報告. 九州支部. 2, 環境系, 2014年03月01日, 日本語, 一般社団法人日本建築学会

  • 404 時間領域有限要素法を用いた波動音響シミュレーションの室形状モデリングに関する研究 : 部材の奥行きの簡略化に関する検討(環境工学)

    相星 光, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 星 和磨, 板井 健

    日本建築学会研究報告. 九州支部. 2, 環境系, 2014年03月01日, 日本語, 一般社団法人日本建築学会

  • アンサンブル平均を利用した材料の吸音特性のin-situ測定に関する研究 : ポーラスモルタルを活用した内装仕上げ材開発への適用

    上水 隆義, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 山口 信

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2014年03月, 日本語, 一般社団法人日本建築学会

  • 時間領域有限要素法による室内音場解析の室形状モデリングに関する研究(その6)音響要素の検討

    板井 健, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 相星 光

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2014年03月, 日本語, 一般社団法人日本建築学会

  • 残響室法吸音率の測定に関する数値解析的研究 : 測定誤差及びばらつきの検討

    畔地 良樹, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 足立 大輔

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2014年03月, 日本語, 一般社団法人日本建築学会

  • 時間領域有限要素法による残響室法吸音率の測定精度改善に関する研究 : 試料への音の入射エネルギの割合に関する検討と実測への適用

    足立 大輔, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 畔地 良樹

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2014年03月, 日本語, 一般社団法人日本建築学会

  • アンサンブル平均を利用した材料の吸音特性のin-situ測定に関する研究 : 反射性材の測定に関する検討

    中野 一樹, 大鶴 徹, 富来 礼次, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2014年03月, 日本語, 一般社団法人日本建築学会

  • 40111 時間領域有限要素法による残響室法吸音率の測定に関する数値解析的研究 : その2 補正した減衰曲線による残響室法吸音率の算出(音場理論・解析(3),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    足立 大輔, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 畔地 良樹

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40106 画像処理技術を利用した室内音場解析に関する基礎的研究 : その2 室の3次元座標計測手法への魚眼レンズの導入(音場理論・解析(2),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    滝川 宇志, 大鶴 徹, 富来 礼次, 奥園 健, 小田 智弘

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40110 時間領域有限要素法による残響室法吸音率の測定に関する数値解析的研究 : その1 減衰曲線の補正に関する検討(音場理論・解析(3),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    畔地 良樹, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 足立 大輔

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40104 時間領域有限要素法を用いた波動音響シミュレーションの室形状モデリングに関する研究 : 窓形状のモデリングに関する検討(音場理論・解析(2),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    相星 光, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 板井 健

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40105 建築材料の吸音特性の現場測定に関する数値解析的検討 : 音源-試料間の距離と測定誤差(音場理論・解析(2),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    上水 隆義, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 松島 梨花子

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40115 アンサンブル平均を利用した材料の吸音特性のin-situ測定に関する研究 : 反射性材料の測定に関する基礎的検討(音響材料,環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    中野 一樹, 大鶴 徹, 富来 礼次, 奥園 健, Kusno Asniawaty, 柳池 将俊

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40102 時間領域有限要素法を用いた波動音響シミュレーションの室形状モデリングに関する研究 : その1 単語と音楽の聴取に関する主観評価実験の設定(音場理論・解析(2),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    岡本 則子, 大鶴 徹, 富来 礼次, 奥園 健, 板井 健, 相星 光

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 40103 時間領域有限要素法を用いた波動音響シミュレーションの室形状モデリングに関する研究 : その2 単語と音楽の聴取に関する主観評価実験の結果(音場理論・解析(2),環境工学I,2013年度日本建築学会大会(北海道)学術講演会・建築デザイン発表会)

    板井 健, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健, 相星 光

    学術講演梗概集, 2013年08月30日, 日本語, 一般社団法人日本建築学会

  • 時間領域有限要素法による室内音場解析の室形状モデリングに関する研究(その5)窓のモデリング

    相星 光, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • 時間領域有限要素法による室内音場予測における分散誤差と室内音響指標算定精度の関係

    奥園 健, 大鶴 徹, 富来 礼次, 岡本 則子

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • アンサンブル平均を利用した材料の吸音特性のin-situ測定に関する研究 : 反射性材の測定に関する基礎的検討

    中野 一樹, 大鶴 徹, 富来 礼次, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • 時間領域有限要素法による室内音場解析の室形状モデリングに関する研究(その4)主観実験による評価;単語と楽音の聴取

    北村 直也, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • 有限要素解析による残響室法吸音率の測定に関する研究 : 減衰曲線の補正に関する検討

    足立 大輔, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • 画像処理技術を利用した室内音場解析に関する基礎的研究 : 魚眼レンズを利用した室の3次元座標計測手法の導入

    大鶴 徹, 富来 礼次, 富来 礼次, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • カフェ空間の音環境改善に関する基礎的研究

    松島 梨花子, 大鶴 徹, 富来 礼次, 奥園 健

    日本建築学会研究報告. 九州支部. AIJ Kyushu Chapter architectural research meeting. 日本建築学会九州支部 編, 2013年03月, 日本語, 一般社団法人日本建築学会

  • 40074 材の吸音特性のin-situ測定に関する数値解析的検討 : 音源条件と測定誤差の関係(音場理論・解析(1),環境工学I,2012年度大会(東海)学術講演会・建築デザイン発表会)

    松島 梨花子, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集, 2012年09月12日, 日本語, 一般社団法人日本建築学会

  • 40082 時間領域有限要素法による室内音場解析の室形状モデリングに関する研究 : その3 聴感実験による解析精度の基礎的評価(音場理論・解析(2),環境工学I,2012年度大会(東海)学術講演会・建築デザイン発表会)

    相星 光, 大鶴 徹, 富来 礼次, 奥園 健, 岡本 則子

    学術講演梗概集, 2012年09月12日, 日本語, 一般社団法人日本建築学会

  • 40078 画像処理技術を利用した室内音場解析に関する基礎的研究(音場理論・解析(2),環境工学I,2012年度大会(東海)学術講演会・建築デザイン発表会)

    小田 智弘, 大鶴 徹, 富来 礼次, 奥園 健, 中野 一樹

    学術講演梗概集, 2012年09月12日, 日本語, 一般社団法人日本建築学会

  • 40076 修正積分則を用いた時間領域有限要素法による室内音場解析 : 不整形要素と吸音を有する音場への適用性(音場理論・解析(1),環境工学I,2012年度大会(東海)学術講演会・建築デザイン発表会)

    奥園 健, 大鶴 徹, 富来 礼次, 岡本 則子

    学術講演梗概集, 2012年09月12日, 日本語, 一般社団法人日本建築学会

  • 40073 残響室法吸音率の測定精度改善に関する研究 : 音線法と時間領域有限要素法の結果との比較(音場理論・解析(1),環境工学I,2012年度大会(東海)学術講演会・建築デザイン発表会)

    足立 大輔, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集, 2012年09月12日, 日本語, 一般社団法人日本建築学会

  • 405 画像計測法を利用した室内音場予測に関する基礎的検討(環境工学)

    小田 智弘, 大鶴 徹, 富来 礼次, 奥園 健, Yahya Mush Nizam bin, 長澤 利喜

    日本建築学会研究報告. 九州支部. 2, 環境系, 2012年03月01日, 日本語, 一般社団法人日本建築学会

  • 402 残響室法吸音率の測定に関する有限要素解析 : 音線法による結果との比較(環境工学)

    中川 竜也, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    日本建築学会研究報告. 九州支部. 2, 環境系, 2012年03月01日, 日本語, 一般社団法人日本建築学会

  • 403 Modified integration ruleを用いた音響要素による時間領域有限要素法の適用範囲の拡張(環境工学)

    丸山 一成, 大鶴 徹, 富来 礼次, 奥園 健, 岡本 則子

    日本建築学会研究報告. 九州支部. 2, 環境系, 2012年03月01日, 日本語, 一般社団法人日本建築学会

  • 40151 アンサンブル平均を利用した材料の吸音特性のin-situ測定法 : 時間領域有限要素法による測定のモデル化(音響材料,環境工学I)

    芝田 隆宏, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 40146 残響室法吸音率の補正に関する有限要素解析 : その1 試料への音の入射エネルギに関する検討(音場解析(2),環境工学I)

    富来 礼次, 大鶴 徹, 岡本 則子, 奥園 健, 中川 竜也

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 40145 室内音場の簡易な予測手法に関する研究 : Neural Networkおよび画像処理技術の導入(音場解析(2),環境工学I)

    小田 智弘, Musli Nizam Yahya, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 40147 残響室法吸音率の補正に関する有限要素解析 : その2 補正値算出に関する基礎的検討(音場解析(2),環境工学I)

    中川 竜也, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 40139 時間領域有限要素法による室内音場解析の室形状モデリングに関する研究 : その2 室形状モデル化手法と評価指標の提案(音場解析(1),環境工学I)

    北村 直也, 大鶴 徹, 富来 礼次, 岡本 則子, 奥園 健

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 40138 時間領域有限要素法による室内音場解析 : 修正積分則を用いた音響要素の適用(音場解析(1),環境工学I)

    丸山 一成, 大鶴 徹, 富来 礼次, 奥園 健, 岡本 則子

    学術講演梗概集. D-1, 環境工学I, 室内音響・音環境, 騒音・固体音, 環境振動, 光・色, 給排水・水環境, 都市設備・環境管理, 環境心理生理, 環境設計, 電磁環境, 2011年07月20日, 日本語, 一般社団法人日本建築学会

  • 有限要素法による実在建築空間の音場予測

    奥園健, 大鶴徹, 富来礼次, 岡本則子, 巳之口俊史

    九州大学情報基盤研究開発センター全国共同利用システム広報, 2009年10月, 日本語

  • 実験室における小サイズの固定窓の遮音性能と既存理論による予測

    三村 茉莉絵, 塚本 陽平, 富川 義弘, 奥園 健, 阪上 公博

    日本音響学会建築音響研究委員会, 2022年03月28日, 日本語, 日本国, 遮音性の高い窓の効率的な開発には、高精度な窓の遮音性能の予測技術 が不可欠である.本稿では,窓の遮音性能の予測技術構築のファーストステップとして,最も構造が単純なFIX 窓を対象とし,実寸大でサイズの異なる5種類の窓の音響透過損失,振動特性,総合損失係数を実験室において測定し,窓サイズによる遮音性能の違いについて分析を行った.さらに,測定した総合損失係数を用いるこ とで,単一板の音響透過損失を予測する既存理論によって,実寸大の窓の遮音性能 を予測できるか検証した.結果として,実験室における FIX 窓の遮音性能はコインシデンス周波数以上では,明確なサイズ依存性を確認した.しかし,コインシデンス周波数以下では,最小サイズの窓をのぞき,サイズによる違いは確認されなかっ た.また,理論によるFIX窓の遮音特性の予測は,実測値の傾向を定性的には説明できるものの,定量的にはより小さな窓及びコインシデンス周波数近傍で大きな差が生じることが分かった., 国内会議, 国際共著していない

    口頭発表(一般)

  • 大規模室内音響解析のための並列陽的時間領域FEM

    吉田卓彌, 奥園健, 阪上公博

    日本音響学会春季研究発表会, 2022年03月10日, 日本語

    口頭発表(一般)

  • 音響材料の波動性を考慮した時間領域FEMによる 3 次元音響解析−その2 微細穿孔板の拡張作用モデル−

    吉田卓彌, 奥園健, 阪上公博

    日本音響学会春季研究発表会, 2022年03月10日, 日本語

    口頭発表(一般)

  • 音響材料の波動性を考慮した時間領域FEMによる 3 次元音響解析−その 1 周波数領域FEMとの比較−

    奥園健, 吉田卓彌, 阪上公博

    日本音響学会春季研究発表会, 2022年03月10日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • プレナム構造のドアへの適用に関する基礎的検討−実大ドア模型による実験的検討−

    阪上公博, 松村宗一郎, 奥園健

    日本音響学会春季研究発表会, 2022年03月09日, 日本語

    口頭発表(一般)

  • 二重窓の遮音性能の実用的予測に関する基礎的考察(2)−予測理論提案に向けた試み−

    塚本陽平, 玉井芳, 阪上公博, 奥園健, 富川義弘

    日本音響学会春季研究発表会, 2022年03月09日, 日本語

    口頭発表(一般)

  • 二重窓の遮音性能の実用的予測に関する基礎的考察(1)−既存理論の適用の検討−

    塚本陽平, 玉井芳, 阪上公博, 奥園健, 富川義弘

    日本音響学会春季研究発表会, 2022年03月09日, 日本語

    口頭発表(一般)

  • 多孔質仕切りによる単一MPP吸音体の性能向上に関する数値解析的検討

    岡山優生, 奥園健, 阪上公博

    日本音響学会秋季研究発表会, 2021年09月09日, 日本語

    口頭発表(一般)

  • 修正アダムス法を用いた陽的時間領域 FEM による室内音場解析−周波数依存の吸音境界の実装−

    杉本優衣, 吉田卓彌, 奥園健, 阪上公博

    日本音響学会秋季研究発表会, 2021年09月08日, 日本語

    口頭発表(一般)

  • Partition of Unity FEM による室内音場解析−頑健な平面波数の設定に関する検討−

    向江俊一, 奥園健, 阪上公博

    日本音響学会秋季研究発表会, 2021年09月08日, 日本語

    口頭発表(一般)

  • FEM による実験室環境における単板固定窓の音響透過損失の予測

    三村 茉莉絵, 奥園 健, 阪上 公博

    日本音響学会建築音響研究委員会, 2022年08月09日, 日本語, 本稿では,実験室環境における単板固定窓のランダム入射音響透過損 失を予測するための,効率的な数値モデルについて議論した.入射条件として理想的な拡散入射を仮定した上で,3 種の FEM モデルによる音響透過損失の予測値をサイズの異なる 5 種類の単板固定窓の実測値と比較し,予測精度と計算コストを議論した.まず,窓部のみを離散化するモデルについて,2 種類の損失係数の与え方で音響透過損失を実測値と比較した.次に,窓部近傍の入射側・透過側空間を半自由空間として離散化することで,窓周辺のニッシェまで含めた強連成モデルによる 1 kHz 以下での音響透過損失の予測精度を検証した.最後に,ニッシェを含めた弱連成モデルの適用性を検証し,強連成モデルと概ね同等の精度でより効率的な予測が可能であることを明らかにした., 国内会議, 国際共著していない

    口頭発表(一般)

  • 陽的時間領域有限要素法による大規模室内音響解析

    吉田 卓彌, 奥園 健, 阪上 公博

    日本音響学会建築音響研究委員会, 2022年08月09日, 日本語, 波動音響学に基づく新しい室内音場予測手法として陽的時間領域 FEM による大規模音響解析手法を提案する.提案法は時空間離散化誤差を最適化することで音圧場の高精度な近似を可能とし,各種吸音体を局所作用性の周波数依存吸音境界条件によりモデル化できる.さらに領域分割型の並列計算により高速な音場予測を実現している.まず,提案法の妥当性と計算性能のそれぞれを小立方体室を対象とした周波数領域 FEM と 2 次得精度の陰的 TD-FEM との比較により検証し,粗い時空間離散化でより高精度かつ高効率な解析がで きることを示す.次に,512 コアを用いた MPI-OpenMP ハイブリッド並列のもと,1 億 5 千万自由度のオーディトリアムモデル内の 3 kHz までの周波数成分を含む 3 s 間のインパルス応答を 9,000 s 以内に解析可能なことを示す., 国内会議, 国際共著していない

    口頭発表(一般)

  • 平面波エンリッチメントを用いた FEM による 2 次元室内音響解析手法の頑健性と効率に関する検討

    奥園 健, 向江 俊一, 阪上 公博

    日本音響学会建築音響研究委員会, 2022年04月28日, 日本語, 日本国, 平面波エンリッチメントを用いた PUFEM(PW-FEM)の室内音響解析における頑健性と従来の 1 次と 2 次 FEM に対する効率について議論する。形状の複雑さの異なる 2 種類のオフィスモデルを設定し、室形状の複雑さとメッシュの 空間分解能が解析の精度と頑健性に与える影響を参照解との比較により検証した。 主たる結果として、メッシュの最大要素サイズを解析上限周波数の波長程度とすることで、PW-FEM は広帯域に渡り、より高い頑健性を示すことを明らかにした。さらに、従来 FEM に比べ精度とメモリの観点から PW-FEM の優位性を示すとともに、2 次 FEM と比較して、PW-FEM は長時間に渡り高精度なインパルス応答波形を保つことを明らかにした。

    口頭発表(一般)

  • クラウドコンピューティングを用いた並列陽的 FEM による室内音響解析

    吉田 卓彌, 奥園 健, 阪上 公博

    日本音響学会秋季研究発表会, 2022年09月15日, 日本語, 国内会議

    口頭発表(一般)

  • 意匠性の高い不均質MPP吸音体のデザインに関する基礎的研究

    阪上公博, 草鹿みどり, 奥園健

    日本音響学会秋季研究発表会, 2022年09月14日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

  • 実験室環境における単板固定窓の遮音性能予測のための有限要素モデリングに関する検討

    三村茉莉絵, 奥園健, 阪上公博

    日本音響学会秋季研究発表会, 2022年09月14日, 日本語, 国内会議, 国際共著していない

    口頭発表(一般)

所属学協会

  • 日本騒音制御工学会

  • 日本音響学会

  • 日本建築学会

共同研究・競争的資金等の研究課題

  • 可聴全域の室内音響予測を可能とする波動数値解析手法の確立

    奥園 健

    日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 神戸大学, 2020年04月 - 2023年03月, 研究代表者

  • 奥園 健

    学術研究助成基金助成金/若手研究(B), 2017年04月 - 2020年03月, 研究代表者

    競争的資金

  • 大嶋 拓也

    日本学術振興会, 科学研究費助成事業/基盤研究(B), 2016年04月 - 2020年03月

    競争的資金

  • 奥園 健

    学術研究助成基金助成金/若手研究(B), 2015年04月 - 2017年03月, 研究代表者

    競争的資金

  • 奥園 健

    日本学術振興会, 科学研究費助成事業/特別研究員奨励費, 2009年04月 - 2010年03月, 研究代表者

    競争的資金

  • 音響材料の周波数・入射角依存性を考慮した時間領域有限要素法による室内音響解析に関する研究

    公益財団法人鹿島学術振興財団, 研究助成, 2021年04月 - 2022年03月, 研究代表者

    This project aims to develop novel wave-based acoustic simulation methods based on the time-domain finite-element method (FEM) as a highly accurate room acoustics design tool. As the salient point of novelty of the project, we proposed two time-domain FEMs that can consider frequency and incident angle dependence of acoustic materials. A proposed implicit time-domain FEM can compute indoor sound environments with significantly higher efficiency while keeping accuracy compared to frequency-domain FEM, which is a standard selection for acoustic simulations. Also, the presented implicit formulation has a high generality that can apply to any finite element with different shapes and polynomial orders. Another domain decomposition method (DDM) based parallel explicit time-domain FEM, which uses a unique formulation, can realize further high-speed computation under a high-performance computing system with many CPU cores. A basic performance examination with 512 CPU cores showed that the proposed DDM based explicit time-domain FEM could simulate room impulse response of a large auditorium with 3 s time length, including frequency component up to 3 kHz within 9000 s.

    その他