Updated on 2024/03/19

写真a

 
OHSHIMA Takuya
 
Organization
Academic Assembly Institute of Science and Technology SEISAN DESIGN KOUGAKU KEIRETU Associate Professor
Faculty of Engineering Department of Engineering Associate Professor
Title
Associate Professor
External link

Degree

  • 修士(工学) ( 1998.3   東京大学 )

  • 博士(環境学) ( 2005.9   東京大学 )

Research Interests

  • Urban acoustics

  • Computational acoustics

  • Computational aeroacoustics

  • Outdoor sound propagation

Research Areas

  • Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Architectural environment and building equipment

Research History

  • Niigata University   Faculty of Engineering Department of Engineering   Associate Professor

    2017.4

  • Niigata University   Abolition organization Environmental Design   Associate Professor

    2013.10 - 2017.3

  • Niigata University   Graduate School of Science and Technology Environmental Science and Technology   Assistant Professor

    2010.4 - 2013.9

  • Niigata University   Faculty of Engineering Department of Civil Engineering and Architecture   Assistant Professor

    2000.11 - 2013.9

Professional Memberships

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Papers

  • A Study on Interpolation Methods for Noise Level of Road Traffic Noise Behind Building Complex in Urban Areas Reviewed

    Yudai Yamashiro, Kazunori Harada, Akiko Sugahara, Yasuhiro Hiraguri, Takuya Oshima, Yoshinori Saito, Satoshi Atobe

    79 ( 3 )   140 - 147   2023.3

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.20697/jasj.79.3_140

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  • Classification of ground states using airborne hyper- spectral imagery for wide-area prediction of noise propagation Reviewed

    Yumi Kurosaka, Takuya Oshima, Yasuhiro Hiraguri, Takeshi Okuzono

    78 ( 11 )   635 - 645   2022.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.20697/jasj.78.11

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  • A Study on the Application of Road Traffic Noise Map through the Case of Higashiosaka City Reviewed

    Satoshi Atobe, Yoshinori Saito, Kazunori Harada Takuya, Oshima Yudai Yamashiro, Yasuhiro Hiraguri

    53 ( 6 )   1076 - 1080   2022.10

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    DOI: 10.11351/jsaeronbun.53.1076

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  • SciPy 1.0: fundamental algorithms for scientific computing in Python Reviewed International journal

    Pauli Virtanen, Ralf Gommers, Travis E. Oliphant, Matt Haberland, Tyler Reddy, David Cournapeau, Evgeni Burovski, Pearu Peterson, Warren Weckesser, Jonathan Bright, Stéfan J. van der Walt, Matthew Brett, Joshua Wilson, K. Jarrod Millman, Nikolay Mayorov, Andrew R. J. Nelson, Eric Jones, Robert Kern, Eric Larson, C J Carey, İlhan Polat, Yu Feng, Eric W. Moore, Jake VanderPlas, Denis Laxalde, Josef Perktold, Robert Cimrman, Ian Henriksen, E. A. Quintero, Charles R. Harris, Anne M. Archibald, Antônio H. Ribeiro, Fabian Pedregosa, Paul van Mulbregt, Aditya Vijaykumar, Alessandro Pietro Bardelli, Alex Rothberg, Andreas Hilboll, Andreas Kloeckner, Anthony Scopatz, Antony Lee, Ariel Rokem, C. Nathan Woods, Chad Fulton, Charles Masson, Christian Häggström, Clark Fitzgerald, David A. Nicholson, David R. Hagen, Dmitrii V. Pasechnik, Emanuele Olivetti, Eric Martin, Eric Wieser, Fabrice Silva, Felix Lenders, Florian Wilhelm, G. Young, Gavin A. Price, Gert-Ludwig Ingold, Gregory E. Allen, Gregory R. Lee, Hervé Audren, Irvin Probst, Jörg P. Dietrich, Jacob Silterra, James T Webber, Janko Slavič, Joel Nothman, Johannes Buchner, Johannes Kulick, Johannes L. Schönberger, José Vinícius de Miranda Cardoso, Joscha Reimer, Joseph Harrington, Juan Luis Cano Rodríguez, Juan Nunez-Iglesias, Justin Kuczynski, Kevin Tritz, Martin Thoma, Matthew Newville, Matthias Kümmerer, Maximilian Bolingbroke, Michael Tartre, Mikhail Pak, Nathaniel J. Smith, Nikolai Nowaczyk, Nikolay Shebanov, Oleksandr Pavlyk, Per A. Brodtkorb, Perry Lee, Robert T. McGibbon, Roman Feldbauer, Sam Lewis, Sam Tygier, Scott Sievert, Sebastiano Vigna, Stefan Peterson, Surhud More, Tadeusz Pudlik, Takuya Oshima, Thomas J. Pingel, Thomas P. Robitaille, Thomas Spura, Thouis R. Jones, Tim Cera, Tim Leslie, Tiziano Zito, Tom Krauss, Utkarsh Upadhyay, Yaroslav O. Halchenko, Yoshiki Vázquez-Baeza

    Nature Methods   17   261 - 272   2020.2

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    DOI: 10.1038/s41592-019-0686-2

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  • Influence of weather on the acoustical properties of a ground surface: measurements and models Reviewed

    Kurosaka Yumi, Oshima Takuya, Honda Meiji

    NOISE CONTROL ENGINEERING JOURNAL   66 ( 6 )   505 - 522   2018.12

  • Numerical analysis of three-dimensional acoustic field with background flow using constrained interpolation profile method Reviewed

    Fukuda Akihiro, Okubo Kan, Oshima Takuya, Tsuchiya Takao, Kanamori Masashi

    JAPANESE JOURNAL OF APPLIED PHYSICS   57 ( 7 )   2018.7

  • Study on applicability of extended and local reaction-based theoretical model calculations and finite-difference numerical simulations for sound fields by a point source above a ground surface

    Takuya Oshima, Yumi Kurosaka

    Journal of Environmental Engineering (Japan)   83 ( 746 )   355 - 363   2018.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Architectural Institute of Japan  

    The validity and applicability of an extended-reaction theoretical model, two local-reaction theoretical models and a finitedifference time-domain numerical model for outdoor sound propagation that take the ground reflection into account are tested varying the flow resistivity from 75 to 20 000kPa-s/m2. It was found from comparisons of the results that (1) the validity of the extended reaction model is confirmed under low flow resistivity, (2) the local reaction is a valid assumption for the tested grounds, (3) the two local reaction models agreed with each other and (4) the numerical model differed from the theoretical models under low source height, long range and high flow resistivity conditions.

    DOI: 10.3130/aije.83.355

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  • A basic investigation for prediction of outdoor sound propagation in large area using fast multipole boundary element method Reviewed

    Yosuke Yasuda, Hidehisa Sekine, Kazutaka Higuchi, Takuya Oshima

    Acoustical Science and Technology   37 ( 2 )   87 - 90   2016

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Acoustical Society of Japan  

    The applicability of the FMBEM to large outdoor problems was basically investigated. Conclusions are as follows. (i) The computational costs of the LF-FMBEM have no systematic relation with model size (root cell size) up to 1-km scale models. (ii) An increase in the root cell size directly increases the computational costs of the HF-FMBEM. (iii) It is much more inefficient in the HF-FMBEM to simply reduce the largest cell size used for computation with keeping high computational accuracy. (iv) An empirical formula proposed in Ref. [7] for the truncation number of infinite summation in the HF-FMBEM gives good values for high computational accuracy even in the range of kD ≤ 4
    000, which corresponds to f ≤ 2
    500 Hz with the root cell 200m on each side, if an appropriate value is chosen for its parameter.

    DOI: 10.1250/ast.37.87

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  • Distinct effects of moisture and air contents on acoustic properties of sandy soil Reviewed

    Takuya Oshima, Yasuhiro Hiraguri, Takeshi Okuzono

    JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA   138 ( 3 )   EL258 - EL263   2015.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ACOUSTICAL SOC AMER AMER INST PHYSICS  

    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

    DOI: 10.1121/1.4929736

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  • Three-dimensional urban acoustic simulations and scale-model measurements over real-life topography Reviewed

    Takuya Oshima, Takashi Ishizuka, Takahide Kamijo

    JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA   135 ( 6 )   EL324 - EL330   2014.6

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    Comparisons of finite-difference time-domain sound propagation simulations over real-life urban topography with scale-model experimental measurements are performed. A 1:100 scale model for the measurements and full-scale input geometry for the simulations are created by using digital geographic datasets. The sound pressure levels obtained by the measurements and simulations resulted in approximately 2 dB of root mean square error in the 125 and 250 Hz octave bands, and 4 dB in 500 Hz. Visualizations of a low-frequency sound propagation case by the measurement and simulation clearly show the wave phenomena caused by buildings and natural terrain. (C) 2014 Acoustical Society of America

    DOI: 10.1121/1.4879672

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  • Study on state of cop and regional characteristics of Apf for room air conditioners

    Shin-Ichi Akabayashi, Jun Sakaguchi, Takuya Oshima, Hiroyuki Ichikawa, Yuki Arinami

    AIJ Journal of Technology and Design   20 ( 44 )   187 - 190   2014.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:日本建築学会  

    A conventional selection criterion of room air conditioners based on rated performance is considered suboptimal from the standpoint of energy efficiency. In order to help consumers evaluate energy performance, annual performance factor (APF) was introduced in the 2005 revision of JIS C 9612. However, APF assumes thermal environment of Tokyo, which makes regional deviation of APF remain unknown. In the present study, rated coefficients of performance (COPs) and market prices of year 2012 models of air conditioners are collected. From the collection, APFs are calculated at nine representative cities in Japan to quantify regional characteristics of APF.

    DOI: 10.3130/aijt.20.187

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  • Geometry reconstruction and mesh generation techniques for acoustic simulations over real-life urban areas using digital geographic information

    Takuya Oshima, Yasuhiro Hiraguri, Masashi Imano

    Acoustical Science and Technology   35 ( 2 )   108 - 118   2014

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    With the recent progresses in computer performance and simulation techniques, it is becoming feasible to apply full three-dimensional wave-based numerical simulation techniques to large-scale problems of real-life sound propagation outdoors. In the present paper, a reconstruction technique for real-life urban geometries with full reproduction of the roof shapes and for the ground profiles using digital geographic information is presented. Also, a generation technique for the uniform rectilinear grid used in finite-difference time-domain simulations is presented. The types of geographic dataset used for the reconstruction are a digital surface model and a two-dimensional building outline map. For comparison, another geometry with flat building roofs, which is the type of geometry used in former noise-mapping studies using empirical models, is created. Comparison of the results of finitedifference time-domain acoustic simulations performed over the geometries shows sound pressure level differences above and behind buildings. The maximum level difference of 10 dB in magnitude indicates the necessity of proper reconstruction of the roof shapes in real-life urban acoustic simulations. © 2014 The Acoustical Society of Japan.

    DOI: 10.1250/ast.35.108

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  • Linearized Euler simulations of sound propagation with wind effects over a reconstructed urban terrain using digital geographic information Reviewed

    Takuya Oshima, Masashi Imano, Yasuhiro Hiraguri, Yoshikazu Kamoshida

    APPLIED ACOUSTICS   74 ( 12 )   1354 - 1366   2013.12

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    The procedure of sound propagation calculation employing the linearized Euler (LE) model has been known to be complex because the procedure requires a chaining of two distinct simulations, namely a fluid dynamics simulation (CFD) in order to solve the background flow field, and a succeeding sound propagation simulation using the LE model over the flow field. The complexity is considered one of the main reasons why the most of the applications of the model remain in investigations assuming highly abstract geometries. In the study, a streamlined workflow is established for LE simulations over a complex urban terrain with its reconstruction utilizing digital geographic models which provide building outline maps and digital surface elevation information. Focus is given to automatic geometry reconstruction and mesh generations of realistic urban terrain. Subsequent processes of CFD and LE simulations are validated through comparisons with published results of wind-tunnel tests and with theoretical solutions. The workflow is deployed to an actual urban terrain of Nagaoka, Japan. The present technique generates a good reconstruction of urban geometry and subsequent split-hexahedral unstructured grid for CFD software and uniform structured mesh for finite-difference LE simulation. The numerical experiments show differences of up to 5 dB between sound pressure levels obtained by the present reconstruction technique and those by a flat-roof geometry. Also, the wind effects are mostly representable in terms of the source-observation point distance in spite of the complex urban configuration. Subtle wind effects of less than 0.5 dB are observed in crosswind condition as well. (c) 2013 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.apacoust.2013.05.006

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  • Air flow measurements in a scale model of a room and method selection of seeding with tracer particles: Study on PIV measurement and analysis for room air flow distribution Part 1

    Shin-Ichi Akabayashi, Takuya Oshima, Yuki Arinami, Hajime Okubo, Xiaoyun Yang, Jun Sakaguchi

    Journal of Environmental Engineering (Japan)   78 ( 690 )   631 - 638   2013.8

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    This paper describes particle image velocimetry (PIV) air flow measurements in a room model of scale 1:0
    the model has inlets and outlets across its width. The PIV measurements use three types of tracer particles: water mist, oil mist, and metal powder. The air flow distribution and turbulence intensity are measured by PIV with metal powder tracers in four combinations of inlet and outlet positions. The results are as follows
    (1) Among the three tracer particles, metal powder yields the best air flow measurements in the 1:10·scale room model. (2) To obtain uniform luminance, an appropriate tracer particle concentration and increased laser output are required. (3) When the inlet and outlet are located midway across the scale model, the air flow velocity in the room in nearly symmetrical. In this case, air enters straight through the inlet, is sucked into the outlet, and is largely discharged. The air not discharged from the outlet collides with the side-wall of the outlet to forms a symmetrical vortex area.

    DOI: 10.3130/aije.78.631

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  • Peak electricity demand reduction by installation of fuel cell cogeneration system in residences: Part 1 Results of simulations for the district of Tohoku Electric Power Company

    Shin-Ichi Akabayashi, Jun Sakaguchi, Takuya Oshima, Hiroyuki Ichikawa, Yuki Arinami

    Journal of Environmental Engineering (Japan)   78 ( 690 )   639 - 644   2013.8

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    One of the effects of the 2011 Tohoku earthquake and the subsequent power disruptions was an increased demand for electricity. As a result, there have been societal efforts to reduce electricity usage and to provide electrical power more equitably. Private power generation by a fuel cell cogeneration system (FCCGS) recently proposed for home use is expected to advance the efficient utilization of primary energy sources and contribute to energy conservation. In this paper, we present the results of a case study on peak electricity demand by modeling the district served by the Tohoku Electric Power Company. The study analyzes the effects on peak power demand if residences in the district were equipped with FCCGSs. For this study, we assume that the FCCGSs are installed in groups of 100,000 units. The groups are composed of FCCGS units with different rated outputs whose hours of operation throughout the day are distributed among the groups. Power supply, primary energy consumption, and CO2 emission amounts both before and after the installation of FCCGSs are recorded in order to quantify the cut in peak demand for electricity. The results of the study demonstrate that peak demand can be cut if FCCGSs are installed in 5% or less (in winter) and about 25% (in summer) of all the private residences in the district served by Tohoku Electric Power Company.

    DOI: 10.3130/aije.78.639

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  • Investigations of wind conditions around a road embankment and their influence on sound propagation by two-point simultaneous measurements of noise and wind velocity

    Koya Hiroi, Takuya Oshima

    Journal of Environmental Engineering (Japan)   78 ( 686 )   317 - 324   2013.4

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    It has been known that the road traffic noise propagation is affected by the wind. However, not so many studies deal with the effect in conjunction with microscopic wind conditions. In the present study wind conditions around a road embankment and their influence on sound propagation were investigated by two-point simultaneous measurements of noise and wind velocity in an open suburban area. Results show that (1) the wake turbulence by the embankment affects variance in received sound pressure levels, (2) the wind velocity component parallel to the road could also be affecting sound propagation.

    DOI: 10.3130/aije.78.317

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  • Study on the evaluation of cross ventilation performance of detached house by effective air change rate and effective opening area of windows ratio

    Yuki Arinami, Shin-Ichi Akabayashi, Takuya Oshima, Jun Sakaguchi

    Journal of Environmental Engineering (Japan)   78 ( 685 )   277 - 284   2013.3

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    The effect of improving indoor environment by the cross ventilation, the rate to discharge thermal energy by the ventilation is larger than the reduction effects of SET* by indoor air flow. In this study, the relationship between the difference of indoor temperature and outdoor temperature by the effect of ventilation will be less than 1°C and the opening area of windows ratio are calculated for a simple and the standerd AIJ detached house model. The relationship between the air change rate, opening area of windows conditions and cross ventilation performance of the detached house is clarified. The results are as follows
    (1) When air change rate is 20 times/h, the inside air temperature becomes nearly equal to the outside air temperature due to the discharge thermal energy by the ventilation. (2) The opening area of windows ratio tends to be high in the inland, and it tends to be low in the city along the sea in Japan. (3) Results of standard AIJ detached house model, the opening area of windows ratio with which ventilation rate is 20 times/h becomes a low value of feasibility. The opening area of windows ratio with which ventilation rate is 10 times/h becomes a values that may be realized.

    DOI: 10.3130/aije.78.277

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  • Field measurements on wind effects to propagation of road traffic noise over open and flat ground Reviewed

    Takuya Oshima, Masaki Ii

    Applied Acoustics   74 ( 1 )   141 - 149   2013.1

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    There has been carried out a number of experimental studies with regard to wind effects to outdoor sound propagation. Most of the studies deal with propagation from steady-state point source such as a loudspeaker in case of field measurements. However, wind effects to more realistic sources, such as road traffic noise sources which are considered to be time-varying line sources, are hardly known in public literature. In the present study, the wind effects to acoustic propagation from a straight road with intense traffic to an open and flat field were investigated through field measurements in order to specifically illustrate the effects of such sources. Two measurement points were placed at 40 m and 140 m distance from the subject road. The results show that (1) The standard deviations of sound pressure levels (SPLs) at the measurement points were around 2 dB for both receiver distances. (2) The effect of perpendicular component of wind velocity to the road direction was slightly stronger than the ASJ Model which was mostly derived from point-source experiments. (3) The effect of source time-variance was effectively taken out by taking the difference in SPLs at the nearby and distant measurement points, in which case the standard deviations of the excess attenuation were reduced to around 1.3 dB. (4) Slight tendency of coherence magnitude of sound pressure between the receivers converging to zero with increasing turbulent kinetic energy is observed in 125 Hz and 250 Hz bands. Meanwhile, the effect of parallel wind velocity component to the road still remained unclear and thus requires further investigations. © 2012 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.apacoust.2012.07.003

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  • Time-domain outdoor acoustic simulation of a real-life area using land cover classification identified by airborne hyperspectral imagery

    Takuya Oshima, Yasuhiro Hiraguri, Kazuma Hoshi

    Acoustical Science and Technology   34 ( 5 )   364 - 366   2013

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    The article examines time-domain outdoor acoustic simulation of a real-life area using land cover classification identified by airborne hyperspectral imagery. In order to solve the identification problem, the authors presented a classification technique of using airborne hyperspectral imagery for land cover types in a real-life area. The simulation employs a porous-medium model for the solution of acoustic absorption by the surfaces. A validation of the porous-medium model through comparisons with exact solutions is given. The results are compared with those obtained assuming perfectly reflecting surfaces. The source is a coherent linear Gaussian pulse with a full width at half maximum of 1.25m and an amplitude of 1 Pa placed on a road, assuming a road traffic noise source.

    DOI: 10.1250/ast.34.364

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  • Basic investigation on estimation of land cover classification conforming to the ASJ RTN-model using hyperspectral imaging data

    Yasuhiro Hiraguri, Takuya Oshima, Kazuma Hoshi

    Acoustical Science and Technology   34 ( 5 )   367 - 370   2013

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    The article presents a possible land cover classification estimation technique specialized for acoustic simulations using high-accuracy hyperspectral imaging data through a case study using a Nagaoka sample. The image was obtained by PASCO Corp. on 5 June 2004 using the Airborne Imaging Spectroradiometer for Application (AISA), which is a hyperspectral sensor with a 1m spatial resolution developed by Spectral Imaging Ltd. The image data comprise 67 bands, covering both the visible and a part of near-infrared wavelengths from 400 nm to 1,000 nm. Spectral band widths are equally spaced by 8-9 nm. The spectrum value at each picture element indicates a normalized spectral reflectance, which is calculated based on the spectral radiance of the ground surface and the sun observed simultaneously. The land cover classification that should be estimated is determined by referring to ASJ RTN-Model 2008 in the first step to discuss classification methods.

    DOI: 10.1250/ast.34.367

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  • Efficient technique in low-frequency fast multipole boundary element method for plane-symmetric acoustic problems Reviewed

    Yosuke Yasuda, Kazutaka Higuchi, Takuya Oshima, Tetsuya Sakuma

    ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS   36 ( 10 )   1493 - 1501   2012.10

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    The fast multipole boundary element method (FMBEM) has been well known as a highly efficient BEM with the use of the fast multipole method (FMM). In the present paper, an efficient technique for plane-symmetric acoustic problems is proposed in the framework of an FMBEM based on the original multipole expansion theory (FMBEM for low-frequency problems: LF-FMBEM). Presented here are concrete computational procedures, which are based on the symmetries among multipole expansion coefficients for a plane-symmetric sound field produced by monopole or dipole sources. The proposed technique is straightforwardly applicable to a variety of formulations for the BEM, such as hypersingular, Burton-Miller, and indirect formulations. Numerical results show an ideal improvement of computational efficiency, with the proposed technique reducing both the computation time and required memory to about 1/2(nsym) of those using the standard LF-FMBEM, where n(sym) is the number of planes of symmetry. (c) 2012 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.enganabound.2012.04.006

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  • Integration of BIM and Modularization of Elements for CFD in CAE Software Tools for Architectural Environment

    KONO Ryohei, KATO Shinsuke, KUBA Masayuki, MIKI Hideki, OSHIMA Takuya, OURA Makoto, SAKATA Minoru, YANAGIHARA Ryuji, ISHIZAKI Yoji, ICHINOSE Masayuki, ADACHI Yoshinobu, DIAO Yunting, HIRANO Masayuki, IKEJIMA Kaoru, IMANO Masashi, ITO Hisaharu

    Transactions of the Society of Heating,Air-conditioning and Sanitary Engineers of Japan   36 ( 174 )   15 - 21   2011

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    Language:Japanese   Publisher:公益社団法人 空気調和・衛生工学会  

    In recent years, the use of BIM for commercial applications of architecture has been increasing. BIM is used for planning, schematic design, working drawing, maintenance, management, and so on. When CFD simulation is performed for developing the design of air-conditioning systems, it is usually required to define the geometry of HVAC systems and boundary conditions such as the value of airflow velocity at the supply opening. If BIM is employed, such data as well as information can be extracted from BIM into the simulation in the form of "CFD parts." "Subcommittee of Integration of BIM and Modularization of Elements for CFD," which is a part of "The Society of Heating, Air-Conditioning and Sanitary Engineers of Japan," is deciding the data formats and the guidelines for the use of BIM, and is promoting it. This paper shows the current situation of research involving BIM. The data coupling of BIM between thermal load calculation and CFD simulation has been examined in one of the activities of "Integrating BIM Working Group," which is a part of the committee.

    DOI: 10.18948/shase.36.174_15

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  • FAST MULTIPOLE BOUNDARY ELEMENT METHOD FOR LOW-FREQUENCY ACOUSTIC PROBLEMS BASED ON A VARIETY OF FORMULATIONS Reviewed

    Yosuke Yasuda, Takuya Oshima, Tetsuya Sakuma, Arief Gunawan, Takayuki Masumoto

    JOURNAL OF COMPUTATIONAL ACOUSTICS   18 ( 4 )   363 - 395   2010.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WORLD SCIENTIFIC PUBL CO PTE LTD  

    The fast multipole boundary element method (FMBEM), which is an efficient BEM that uses the fast multipole method (FMM), is known to suffer from instability at low frequencies when the well-known high-frequency diagonal form is employed. In the present paper, various formulations for a low-frequency FMBEM (LF-FMBEM), which is based on the original multipole expansion theory, are discussed; the LF-FMBEM can be used to prevent the low-frequency instability. Concrete computational procedures for singular, hypersingular, Burton-Miller, indirect (dual BEM), and mixed formulations are described in detail. The computational accuracy and efficiency of the LF-FMBEM are validated by performing numerical experiments and carrying out a formal estimation of the efficiency. Moreover, practically appropriate settings for numerical items such as truncation numbers for multipole/local expansion coefficients and the lowest level of the hierarchical cell structure used in the FMM are investigated; the differences in the efficiency of the LF-FMBEM when different types of formulations are used are also discussed.

    DOI: 10.1142/S0218396X10004243

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  • Numerical analysis of large-scale sound fields using iterative methods part I: Application of Krylov subspace methods to boundary element analysis

    Y. Yasuda, S. Sakamoto, Y. Kosaka, T. Sakuma, N. Okamoto, T. Oshima

    JOURNAL OF COMPUTATIONAL ACOUSTICS   15 ( 4 )   449 - 471   2007.12

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    The convergence behavior of the Krylov subspace iterative solvers towards the systems with the 3D acoustical BEM is investigated through numerical experiments. The fast multipole BEM, which is an efficient BEM based on the fast multipole method, is used for solving problems with up to about 100,000 DOF. It is verified that the convergence behavior of solvers is much affected by the formulation of the BEM (singular, hypersingular, and Burton-Miller formulation), the complexity of the shape of the problem, and the sound absorption property of the boundaries. In BiCG-like solvers, GPBiCG and BiCGStab2 have more stable convergence than others, and these solvers are useful when solving interior problems in basic singular formulation. When solving exterior problems with greatly complex shape in Burton-Miller formulation, all solvers hardly converge without preconditioning, whereas the convergence behavior is much improved with ILU-type preconditioning. In these cases GMRes is the fastest, whereas CGS is one of the good choices, when taken into account the difficulty of determining the timing of restart for GMRes. As for calculation for rigid thin objects in hypersingular formulation, much more rapid convergence is observed than ordinary interior/exterior problems, especially using BiCG-like solvers.

    DOI: 10.1142/S0218396X07003470

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  • APPLICATION OF KRYLOV SUBSPACE METHODS TO BOUNDARY ELEMENT SOUND FIELD ANALYSIS : Numerical analysis of large-scale sound fields using iterative solvers Part 1

    YASUDA Yosuke, KOSAKA Yoshiyuki, OKAMOTO Noriko, OSHIMA Takuya, SAKUMA Tetsuya, SAKAMOTO Shinichi

    Journal of Environmental Engineering (Transactions of AIJ)   71 ( 605 )   15 - 22   2006

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    Iterative solvers are widely used for solving large systems of linear equations, and applied to the systems obtained with the acoustical FEM and BEM. In the present paper, the convergence behavior of the Krylov subspace iterative solvers towards the systems with the 3-D acoustical fast muftipole BEM, an efficient BEM based on the fast multipole algorithm, is investigated through numerical experiments. The convergence behavior of solvers is much affected by the formulation of the BEM (basic form (BF), normal derivative form (NDF) and Burton-Miller formulation), the complexity of the shape of the problem, and the sound absorption property of the boundaries. In BiCG-like solvers, GPBiCG and BiCGStab2 converge more stable than others, and these solvers are useful when solving interior problems using BF. When solving exterior problems with greatly complex shape using Burton-Miller formulation, all solvers hardly converge without preconditioning, whereas the convergence behavior is much improved with ILU-type preconditioning. In these cases GMRes is the fastest, whereas CGS is one of the good choices, when taken into account the difficulty of determining the timing of restart for GMRes. As for calculation for thin objects using NDF, much more rapid convergence is observed than ordinary interior/exterior problems, especially using BiCG-like solvers.

    DOI: 10.3130/aije.71.15_3

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    Other Link: http://hdl.handle.net/10191/18374

  • FINITE-DIFFERENCE TIME-DOMAIN ACOUSTIC SIMULATION TECHNIQUE IN GENERALIZED CURVILINEAR COORDINATES USING CONTRAVARIANT VELOCITY AND PRESSURE FOR LEAPFROG TIME MARCHING

    OSHIMA Takuya

    Journal of Environmental Engineering (Transactions of AIJ)   71 ( 599 )   9 - 15   2006

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    Language:Japanese   Publisher:日本建築学会  

    Finite-difference time-domain (FDTD) acoustic simulation technique in generalized curvilinear coordinates using contravariant velocity and pressure as variables for two-step leapfrog time marching scheme is presented. The technique excels the conventional generalized curvilinear technique using contravariant velocity, covariant velocity and pressure as variables for three-step time marching, especially in that normal acoustic impedance boundary conditions which are indispensable in practical application are also presented. Validation of the technique through comparison against orthogonal FDTD with staircasing applied in irregularly-shaped sound field shows suppressions of phase error in initial time marching stage and diffusion from staircased boundaries.

    DOI: 10.3130/aije.71.9_1

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  • ESTIMATION TECHNIQUE FOR AERODYNAMIC SOUND RADIATION FROM A CYLINDRICAL BODY UTILIZING PARTIAL-SPAN CFD RESULTS : Its construction and validation through experimental analysis

    OSHIMA Takuya, TERAO Michihito, SEKINE Hidehisa

    Journal of Environmental Engineering (Transactions of AIJ)   70 ( 598 )   15 - 22   2005

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    Estimation technique of aerodynamic sound radiation from a cylindrical body using results of partial-span CFD computation is presented. The technique replaces the calculation of Curie equation in Lighthill-Curle computational aeroacoustics technique, and is based on Morse-Ingard's and Goldstein's theory and coherence model function. The validation of the model function and the technique through wind-tunnel experiment results 1) measured coherence between surface fluid forces on the body surface shows good agreement with the model function, and 2) reasonable agreement is obtained between measured SPL at a receiving point and estimated SPL using the technique.

    DOI: 10.3130/aije.70.15_8

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  • Numerical study on correlation between aeroacoustic sources on uniformly aligned cylindrical bodies

    OSHIMA Takuya, SAKUMA Tetsuya, HIRATE Kotaroh

    Acoustical Science and Technology   24 ( 3 )   139 - 141   2003.5

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    Language:English   Publisher:ACOUSTICAL SOCIETY OF JAPAN  

    DOI: 10.1250/ast.24.139

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10572443

  • An estimation method of total aeroacoustic noise from a cylindrical body by a partial-span computation

    OSHIMA Takuya, SAKUMA Tetsuya, HIRATE Kotaroh

    Acoustical Science and Technology   24 ( 2 )   100 - 102   2003.3

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    DOI: 10.1250/ast.24.100

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    Other Link: http://dl.ndl.go.jp/info:ndljp/pid/10572430

  • Numerical vibro-acoustic analysis of sound insulation perfornmance of wall members based on a 3-D transnsmission model with a membrane/plate

    SAKUMA Tetsuya, OSHIMA Takuya

    Acoustical Science and Technology   22 ( 5 )   367 - 369   2001.9

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    Language:English   Publisher:ACOUSTICAL SOCIETY OF JAPAN  

    DOI: 10.1250/ast.22.367

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  • BASIC STUDY ON NUMERICAL PREDICTION OF AEROACOUSTIC NOISE RADIATED FROM BALUSTERS OF BUILDINGS

    OSHIMA Takuya, IMANO Masashi, SAKUMA Tetsuya, HIRATE Kotaroh

    Journal of Architecture and Planning (Transactions of AIJ)   65 ( 532 )   7 - 13   2000

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    Language:Japanese   Publisher:Architectural Institute of Japan  

    Quantitative methods for predicting aeroacoustic noise radiated from balusters of buildings have been expected as a tool for its effective reduction. We applied a numerical method of solution based on Lighthill-Curle equation. As a basic step, we attempted to predict characteristics of the sound radiated by airflow around a row of square cylinders at Reynolds number 1000 by 2-dimensional analysis. We also made a comparison of solutions of an isolated cylinder wake flow at the same Reynolds number by 2- and 3-dimensional analyses, as a preparation for further improvement of the method.

    DOI: 10.3130/aija.65.7_3

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    Other Link: http://hdl.handle.net/10191/18380

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Books

  • 音環境の数値シミュレーション : 波動音響解析の技法と応用 = Computational simulation of sound environment : techniques and applications of wave‐based acoustics

    日本建築学会( Role: Contributor ,  5.1節,5.3節,7.1節)

    日本建築学会,丸善出版 (発売)  2021.12  ( ISBN:9784818926714

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    Total pages:398p   Language:Japanese

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  • Report on the Great East Jaan Earthquake Disaster: Building Series Volume 8 Building equipments and environment

    ( Role: Joint editor)

    日本建築学会,丸善出版 (発売)  2015.5  ( ISBN:9784818920446

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    Total pages:371p  

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

    Tetsuya Sakuma, Shinichi Sakamoto, Toru Otsuru, Takuya Oshima( Role: Joint author ,  5.1, 5.3, 7.1)

    Springer  2014.8 

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  • はじめての音響数値シミュレーションプログラミングガイド

    日本建築学会, 大嶋 拓也, 石塚 崇, 大久保 寛, 鈴木 久晴, 星 和磨

    コロナ社  2012  ( ISBN:9784339008388

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  • 音環境の数値シミュレーション―波動音響解析の技法と応用

    日本建築学会

    日本建築学会  2011.10  ( ISBN:4818927074

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    Total pages:291  

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MISC

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Presentations

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Works

  • 高速多重極境界要素法に基づいた商用音響解析ソフトウエアの開発

    2004

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Awards

  • 第14回環境音響研究賞

    2023.3   一般社団法人日本音響学会   実在地域の騒音伝搬予測に関する一連の研究

    大嶋拓也, 平栗靖浩

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  • 第18回空気調和・衛生工学会功績賞

    2021.5   公益社団法人空気調和・衛生工学会   次世代型CFDパーツの開発およびBIMによる空調設備設計統合手法に関する調査研究

    公益社団法人空気調和・衛生工学会換気設備委員会BIM・CFDパーツ開発応用小委員会

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  • 空気調和・衛生工学会第14回功績賞

    2017.5   空気調和・衛生工学会   建築環境設計における空調吹出し口のCFDパーツ化およびBIMとの連携手法の提案

    空気調和, 衛生工学会, CFDパーツ化とBIM応用小委員会

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  • 日本建築学会奨励賞

    2008.4   日本建築学会   部分スパン数値流体解析結果を利用した柱状物体からの空力音推定法 -推定手法の構築および実証実験-

    大嶋 拓也

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  • 第23回粟屋潔学術奨励賞

    2006.3   日本音響学会   角柱列状空力音源の物体間相関に対する物体間隔の影響

    大嶋 拓也

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Research Projects

  • 大規模波動音響数値シミュレーションによる防災無線放送の音声明瞭度予測技術の開発

    2022.4 - 2023.3

    System name:研究助成金

    Awarding organization:公益財団法人ユニオンツール育英奨学会

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  • スマートフォンを用いた実測型3次元騒音マッピング技術の適用性検証

    2021.4 - 2022.3

    Awarding organization:公益財団法人内田エネルギー科学振興財団

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  • 環境騒音伝搬予測のための土の流れ抵抗モデルの構築に関する研究

    2021.4 - 2022.3

    System name:学術研究助成

    Awarding organization:公益財団法人山口育英奨学会

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  • モバイルデバイスを用いた3次元実測型騒音マッピングシステムの開発

    2018.6 - 2021.3

    System name:科学研究費補助金 挑戦的研究(萌芽)

    大嶋 拓也

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  • Clarification of low-frequency noise transmission into house and validation of its soundproofing measures

    Grant number:17H03350

    2017.4 - 2020.3

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    Sakuma Tetsuya

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    Grant amount:\16380000 ( Direct Cost: \12600000 、 Indirect Cost:\3780000 )

    Regarding low-frequency sound from outdoors into house, a series of research was conducted by numerical analysis, scale model and real scale experiments: 1) clarification of noise propagation characteristics around house, 2) examination of sound source measures for household equipment, 3) clarification of sound transmission phenomenon into the house , 4) verification of field measurement method of low-frequency sound insulation performance of facade, 5) verification of the effects of various soundproofing measures for wooden house. It was clarified that noise distribution around house changes drastically due to the adjacent house and the fence, and the possibility of noise reduction by the position of equipment. Regarding sound insulation of house, a low-frequency procedure for field measurement method was proposed, and the experiments demonstrated the soundproofing effects of the combination of wall lining and double window system.

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  • 広域環境騒音伝搬予測のための地表面音響特性時空間変動モデルの確立

    2016.4 - 2020.3

    System name:科学研究費補助金 基盤研究(B)

    大嶋 拓也

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  • パッシブ音響トモグラフィによる協調動作型都市環境センサネットワークの基礎研究

    2015.4 - 2018.3

    System name:科学研究費補助金 挑戦的萌芽研究

    大嶋 拓也

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  • 地表面音響特性への気象の影響解明に関する基礎研究

    2014.4 - 2015.3

    System name:学術研究助成事業

    Awarding organization:山口育英奨学会

    大嶋 拓也

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  • Establishment of acoustic performance prediction methods for building elements using numerical testing rooms

    Grant number:25289193

    2013.4 - 2016.3

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    Sakura Tetsuya, YASUDA Yosuke, OSHIMA Takuya, TSUCHIYA Yuzo, INOUE Naohisa

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    Grant amount:\12220000 ( Direct Cost: \9400000 、 Indirect Cost:\2820000 )

    Based on the concept of “numerical acoustic testing room”, the laboratory measurements in reverberation room and anechoic room were modeled, and numerical methods for predicting acoustics performance (insulation, absorption and scattering) of building elements were systemized. Using our in-house FEM and BEM codes, a variety of vibration fields for membrane, plate, elastic body and porous material were coupled with acoustic systems for testing rooms, and an integrated prediction system was developed which is applicable for various element shapes and material compositions. In case studies on transmission loss and absorption coefficient of multi-layer materials, and scattering and diffusion coefficients of new-type diffusers, the prediction system was validated in comparison with measured data.

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  • A development of non-uniform radiant thermal environment simulator by the fusion of non-steady CFD, sunlight and human body analysis model

    Grant number:23360260

    2011.4 - 2016.3

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    SAKAI KOJI, KURABUCHI Takashi, IWAMOTO Shizuo, NAGATA Akihiro, KAJIYA Ryouichi, ENDO Tomoyuki, OSHIMA Takuya, AKAMINE Yoshihiko, ONO Hiroki

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    Grant amount:\20020000 ( Direct Cost: \15400000 、 Indirect Cost:\4620000 )

    In this study, we aimed at "A development of non-uniform radiant thermal environment simulator by the fusion of non-steady CFD, sunlight and human body analysis model". For the purpose, we developed an unsteady database of natural convectional field for validation of CFD models, a numerical human body model for CFD simulation and tried to fusion solar radiation simulation.
    The measurement of the actual non-uniform thermal environment was analyzed by using the simulation model that we built in this study. It was confirmed that the model that we developed in this study had enough analysis precision in a practical use calculation in design stage.

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  • 数値地形情報を用いた実在地域音響数値解析技術の研究開発

    2011.4 - 2014.3

    System name:科学研究費補助金 基盤研究(B)

    大嶋 拓也

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  • マルチフィジックス対応汎用音響数値解析オープンソースパッケージの開発

    2009.4 - 2011.3

    System name:科学研究費補助金 若手研究(B)

    大嶋 拓也

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  • 建築音響数値解析環境整備[若手奨励]特別研究委員会

    2009.4 - 2011.3

    System name:[若手奨励]特別研究委員会

    Awarding organization:日本建築学会

    大嶋 拓也

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  • Development of an advanced room acoustics design scheme based on diffuseness control

    Grant number:21360275

    2009 - 2011

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    SAKUMA Tetsuya, KAWAI Keiji, OSHIMA Takuya, YASUDA Yosuke, TSUCHIYA Yuzo, LEE Hyojin, EDA Kazushi

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    Grant amount:\18850000 ( Direct Cost: \14500000 、 Indirect Cost:\4350000 )

    In room acoustics design, a general methodology regarding reverberation time and room shape has been established, however, details of wall surface and interior finish have been empirically designed. In this research, an index of diffusivity of wall surface,"scattering coefficient" was introduced, developing two measurement methods, and providing a database for a variety of wall structures. Furthermore, a new reverberation theory for rectangular rooms was developed incorporating surface diffusivity, and energy decay in non-diffuse sound field was clarified by the theory, numerical simulation and scale model experiment. Additionally, auditory effect of installing diffuse surface was examined by using an auralization system.

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  • 気象効果を考慮した屋外音響伝搬の数値予測に関する研究

    2007.4 - 2009.3

    System name:科学研究費補助金 若手研究(B)

    大嶋 拓也

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  • Development of virtual house simulator By using unsteady state CFD and thermal environment Simulation method

    Grant number:19360264

    2007 - 2010

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    SAKAI Koji, SAKAMOTO Yuzo, KURABUCHI Takashi, IWAMOTO Shizuo, NAGATA Akihiro, KAJIYA Ryoichi, ENDO Tomoyuki, IMANO Masashi, OOSHIMA Takuya, AKAMINE Yoshihiko, ONO Hiroki

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    Grant amount:\20280000 ( Direct Cost: \15600000 、 Indirect Cost:\4680000 )

    In this study, virtual house simulator using unsteady air flow and thermal environment analysis method was developed for thermal environment of the housing which must synthetically evaluate the complicated phenomenon. Steady and unsteady thermal environment in the living space which adopted different heating system was measured, and the database for the verification was made. As a result that by using analytical model for the observation variously, it carried out the analysis, and that it examined the accuracy in comparison with the observation, it was shown that the simulator developed in this study has the practical accuracy as a thermal environment evaluation of the housing.

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  • Constructing simulacres database on architectural acoustics by large-scale computational methods

    Grant number:19206062

    2007 - 2009

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (A)

    Awarding organization:Japan Society for the Promotion of Science

    OTSURU Toru, KAWAI Yasuhito, FUJINO Seiji, AKITA Masanori, SAKUMA Tetsuya, SAKAMOTO Shinichi, FUKUDA Ryouji, HORINOUCHI Yoshinari, MIDORIKAWA Yoichi, TOMIKU Reiji, TOMIKU Reiji

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    Grant amount:\47710000 ( Direct Cost: \36700000 、 Indirect Cost:\11010000 )

    Computer simulation techniques based on the wave equation are investigated to analyze large-scale sound fields in built environments and a database of sound fields in typical sound fieldsis constructed. Due to the largeness as well as the complexness of the sound field in an actual room, highly efficient computational techniques for solving the math-physical system are required. Appropriate numerical solvers that suit for each sound field to be analyzed are given including the adequate parameter settings. The boundary modeling techniques are also discussed on the problems relating with shape modeling and with absorption modeling. The constructed database consists of six types with eleven rooms. Impulse responses are measured in the rooms and included into the database as well as the other information like CAD data and photographs.

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  • Study on acoustical diagnosis on soundness of porous drainage pavement surface

    Grant number:19360258

    2007 - 2008

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    IWASE Teruo, OSHIMA Takuya

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    Grant amount:\15470000 ( Direct Cost: \11900000 、 Indirect Cost:\3570000 )

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  • Study of establishment of measurement method of acoustic particle velocity and its applications to advanced investigation on acoustical phenomena

    Grant number:17360283

    2005 - 2006

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    IWASE Teruo, YOSHIMURA Junichi, SUGIE Satoshi

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    Grant amount:\11100000 ( Direct Cost: \11100000 )

    Following studies were carried out to establish measurement methods on acoustic particle velocity. Then, application measurements were tried for the confirming of its usefulness to make unsolved acoustical phenomenon clear
    (A) Some calibration methods of the hot wire-type particle velocity sensor were tested for simultaneous measurement with sound pressure microphone. Relative correcting method by the transmission function value or by its approximation equation was effective.
    (B) Applications such as acoustic impedance measurements by use sound particle velocity sensor with microphone were performed. Some acoustic impedance measurements on the field with grass and on the snow-covered ground in the campus of Niigata University were carried out. Other acoustic impedance and sound propagation measurements also carried out on the very wide field with long grass in Hokkaido.
    (C) Calculations of the sound propagation characteristic based on the measured acoustic impedance values were tried, and these results were fairly corresponded to the measured results on the actual field.
    (D) Acoustic admittance measurements by the particle velocity sensor were applied to make clear for acoustical properties of perforated plate, the Helmholtz resonator and slit-type structure which are well known in architectural acoustics. Measured results clearly showed the resonant characteristics by sharp peak in each specific frequency.
    (E) The particle velocity sensor and its directivity were effective in the diagnosis for the soundness of porous drain pavement. It was very effective to realize compact potable inspective instruments.
    (F) The 3-D observation of sound propagation by particle velocity sensor in inserted porous absorber "glass wool" in light weight double wall was tried to investigate the bases of insertion effect of glass wool for the high sound insulation. Even in the case of grazing incidence to the wall, the propagation direction in the glass wool certainly changes to close to normal direction, then it weakened coincident effect.

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  • 屋外建築付帯物から発生する空力騒音の数値予測システム構築に関する研究

    2004.4 - 2006.3

    System name:科学研究費補助金 若手研究(B)

    大嶋 拓也

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  • Study on developing of test method for sound insulation characteristics of light leaf double wall and its applications to realize highly efficient wall structures.

    Grant number:15360309

    2003 - 2004

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    IWASE Teruo, OSHIMA Takuya, YOSHIMURA Junichi

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    Grant amount:\6600000 ( Direct Cost: \6600000 )

    It was tried that the establishment of apparatus to measures high sound insulation performance for the light weight the double leaf wall composed of two leafs of gypsum board.
    The basic system was made by a small anechoic box and by double leaf wall with some interval kept by a spacer putted on the box.
    In this study, improvements were started from forming the floating structure as that a small anechoic box made of the acrylic was supported by glass wool on a floor, and circumference part is surrounded by air space/glass-wool and a sound insulation layer. A gypsum board was used for the layer first. Next, it was changed to the fiber strengthening gypsum board. After some experiments, a fiber strengthening gypsum board was finally used. The first improvements of about 10dB were recognized by such a simple way in high frequency range. The attenuation of about 60dB in the frequency range beyond 1kHz could be observed at the normal condition of sound incidence when any outside layer material was used.
    Furthermore, it became possible that a coincidence effect was observed clearly in the frequency range of 3-4kHz in case of a horizontal sound incidence. Next, it tried the experiment of the sound bridge effect by a wooden stud putted between two gypsum boards. The Effect as the declined sound insulation could be observed this experiment.
    Experiments on the insert effect of glass wool between two leafs of gypsum boards were carried out, too. It could be found the condition with no space between thin glass wool sheets was superior to the condition with certain spaces between thick glass wool sheets.
    Test apparatus and much fundamental information for high sound insulation performance were obtained The purpose of this study was attained as described above.

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  • High-efficiency implementation of the Fast Multipole Boundary Element Method

    2002

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  • 振動応答分析によるコンクリート構造物欠陥部検出に関する数値的研究

    2001.4 - 2002.3

    System name:試験研究費助成

    Awarding organization:内田エネルギー科学振興財団

    大嶋 拓也

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  • Study on Numerical Prediction of Aeroacoustic Noise Radiated from Balusters of Buildings

    Grant number:12450231

    2000 - 2001

    System name:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    HIRATE Kotaroh, OSHIMA Takaya, SAKUMA Tetsuya

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    Grant amount:\7500000 ( Direct Cost: \7500000 )

    True-scale analysis : Sound generation by airflow over square-section balusters of buildings is numerically calculated by a hybrid technique of near-field incompressible flow analysis and far-field integral of Curle equation. Under the conditions of inflow wind velocity of 12m/s and the side length of the square-section balusters of 21mm (the Reynolds number 16,000), the result approximately matched an experimental result in peak frequency, which is higher in Strouhal number than the case of an isolated square cylinder in the same Reynolds number.
    Computational cost reduction method : An estimation method of total sound pressure radiated from such body is introduced by conducting an analysis of its partial span, taking frequency-dependent spanwise correlation of the fluctuating aeroacoustic source into account. The presented method is validated through comparison of the sound pressure estimated by the method and that obtained by a full-span analysis.
    Extension to the method above : To reduce computational resources required for CFD computation further, the authors present a method to estimate the noise from a row of cylinders like balusters by computing its part. The idea is to extrapolate the sound pressure obtained by partial computation using correlation function of the phase angles of fluid forces at each frequency between the cylinders. A computation of a balustrade with eight balusters with the method applied is attempted, where correlation is hardly observed even at the Karman frequency.

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  • Developing study of detecting method for defective part on concrete structure by using laser vibrometer.

    Grant number:12555162

    2000 - 2001

    System name:Grants-in-Aid for Scientific Research

    Research category:Grant-in-Aid for Scientific Research (B)

    Awarding organization:Japan Society for the Promotion of Science

    IWASE Teruo, YOKOTA Akinori, OSHIMA Takuya, DOI Mareyusu, YASUOKA Hirohito

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    Grant amount:\10600000 ( Direct Cost: \10600000 )

    Vibration techniques were examined for detecting of crack or exfoliation part came put on a concrete structure.At first, some kinds of concrete test block with the groove of depth as 10mm-40mm were made for imitating cracks.Next, two kinds the concrete test block with exfoliation of thickness as 20mm were made. By using these test blocks, many analyzes of vibration response on the all area, especially around defective part, were carried out.As the result of these analyzes, it was found that piezoelectric buzzer device was effective for the excitation of vibration in wide frequency range.
    It was also found that laser vibrometer was useful for the observation of vibration, because it made easy positional moving and it had sensitivity in very high frequency range.
    As for detecting of parts of exfoliation, detecting was easy, because there was strong vibration response on such area compared with the sound part in the audio frequency range. As for detecting of crack, the amplitude of vibration response became weak over the groove in the supersonic frequency range. More than 20mm depth of the groove, phase delay in the supersonic frequency range appeared large changes as several ten thousand degrees between both sides of the test groove.
    For the practical detecting technique, pressing down type to the test surface and movable type device for vibration excitation is useful, and dual channel receiving technique for vibration by laser vibrometer was effective to obtain stable analyzed results.
    These techniques were also confirmed to the actual wall surface, and then effective results could be obtained for detection of the crack.
    By only these analyzing techniques in this stage, quantity of the crack depth could not be recognized clearly. So, another sound resonance method tried. Then, prospect of the quantitative detection of crack could be seen.

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  • Numerical researches on aeroacoustic noise radiated from bulsters of buildings

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    Grant type:Competitive

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  • Prediction of sound insulation performance of building elements using discrete vibro-acoustic analysis

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    Grant type:Competitive

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Teaching Experience

  • エンジニアのためのデータサイエンス入門(建築分野)

    2023
    Institution name:新潟大学

  • 建築設備設計演習

    2022
    Institution name:新潟大学

  • 建築環境制御論I

    2021
    Institution name:新潟大学

  • 建築環境解析学演習

    2021
    Institution name:新潟大学

  • 建築環境制御学I

    2021
    Institution name:新潟大学

  • 建築設備設計特論

    2021
    Institution name:新潟大学

  • 建築設計製図Ⅵ

    2020
    Institution name:新潟大学

  • 建築環境制御学演習II

    2020
    Institution name:新潟大学

  • 建築設計製図Ⅶ

    2020
    Institution name:新潟大学

  • 建築設計製図V

    2020
    Institution name:新潟大学

  • 建築環境制御学演習I

    2020
    Institution name:新潟大学

  • 建築設備設計演習

    2020
    -
    2022
    Institution name:新潟大学

  • 総合技術科学演習

    2020
    -
    2021
    Institution name:新潟大学

  • 建築環境工学演習II

    2019
    Institution name:新潟大学

  • 建築環境工学演習I

    2019
    Institution name:新潟大学

  • 工学リテラシー入門(建築分野)

    2017
    Institution name:新潟大学

  • 建築学概論

    2017
    Institution name:新潟大学

  • 卒業研修又は基礎設計

    2016
    Institution name:新潟大学

  • 卒業研究又は設計

    2016
    Institution name:新潟大学

  • 建築環境工学特論

    2014
    Institution name:新潟大学

  • 建築環境制御論Ⅰ

    2014
    -
    2019
    Institution name:新潟大学

  • くらしと環境

    2014
    -
    2016
    Institution name:新潟大学

  • 建築環境工学II

    2013
    Institution name:新潟大学

  • 建築環境制御学II

    2013
    Institution name:新潟大学

  • 研究発表演習Ⅲ(中間発表)

    2013
    -
    2015
    Institution name:新潟大学

  • 環境科学総合演習Ⅲ

    2013
    -
    2015
    Institution name:新潟大学

  • 環境科学セミナーⅢ

    2013
    -
    2015
    Institution name:新潟大学

  • 研究発表演習Ⅲ(学外発表)

    2013
    -
    2015
    Institution name:新潟大学

  • 都市人間環境学Ⅰ

    2013
    -
    2015
    Institution name:新潟大学

  • 環境科学特定研究Ⅲ

    2013
    -
    2014
    Institution name:新潟大学

  • 環境科学特定演習Ⅲ

    2013
    -
    2014
    Institution name:新潟大学

  • 建築環境工学I

    2012
    Institution name:新潟大学

  • 建築環境制御学I

    2012
    Institution name:新潟大学

  • 工学リテラシー入門(建設学科)

    2011
    -
    2016
    Institution name:新潟大学

  • 建築環境解析学演習

    2010
    Institution name:新潟大学

  • 建築環境計画特論

    2010
    Institution name:新潟大学

  • 建築応用数理

    2009
    -
    2012
    Institution name:新潟大学

  • 建築設計製図II

    2008
    Institution name:新潟大学

  • 建築設計製図I

    2008
    Institution name:新潟大学

  • 建築設計製図IV

    2008
    Institution name:新潟大学

  • 建築設計製図III

    2008
    Institution name:新潟大学

  • 建築数理工学

    2008
    -
    2012
    Institution name:新潟大学

  • 建築環境制御学演習

    2007
    -
    2018
    Institution name:新潟大学

  • 建築環境工学演習

    2007
    -
    2018
    Institution name:新潟大学

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