| Project/Area Number |
17560403
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Control engineering
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| Research Institution | Kinki University |
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Principal Investigator |
NAKASAKO Noboru Kinki University, School of Biology-Oriented Science and Technology, Professor, 生物理工学部, 教授 (90188920)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | one-dimensional sound field / random media / random loadings / distributed parameter circuit / sound reduction property / localization / computer simulation / noise control / 分布乗数回路 |
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| Research Abstract |
It is known that a wave cannot propagate long distance in random media and is confined in a small region when the field is excited. In physics it is called the "localization", the phenomenon which is closely related to the cut-off (non-propagating) state of waves in a certain broad frequency band. It is expected that this property can be utilized as a muffler to reduce the sound noise because the sound propagating in random media or random loadings would exhibit strong exponential decay along distance. On the other hand, a one-dimensional acoustic duct can be expressed by a transmission line model commonly used in the study of microwave waveguide. In this research, I focus on the sound decaying property of one-dimensional duct (random duct) and demonstrate the validity of the proposed theory through a computer simulation. The results I obtained in 2005 and 2006 are listed below.
[2005 year] : As the first step of research, I expressed the sound field in duct by a transmission line model, on which I theoretically analyzed the ordinary one-dimensional duct and carried out computer simulation. Based on the circuit representation, I theoretically proposed the sound reduction property in a case when there exist random media in duct. To confirm the validity of the analysis, I performed the computer simulation and showed the existence of the strong exponential decay. These results have been published in a scientific journal and presented in domestic conference.
[2006 year] : Following to the fundamental consideration on the sound reduction problem with randomness in 2005, I theoretically proposed the sound reduction property in a case when there exist random loadings in duct and the extensive simulation makes it clear that the proposed method also enables us to cause the strong exponential decay. These results have been presented in international conferences.
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