Document Detail

Sound shielding by a piezoelectric membrane and a negative capacitor with feedback control.
MedLine Citation:
PMID:  18986928     Owner:  NLM     Status:  MEDLINE    
The design and realization of an adaptive sound-shielding system based on a method to control the effective elastic stiffness of piezoelectric materials are presented in this paper. In this system, the sound-shielding effect is achieved by a sound reflection from the piezoelectric curved membrane fixed in rigid frame and connected to an active analog circuit that behaves as a negative capacitor. The acoustic transmission loss through the curved membrane was measured for the incident sound of frequency 1.6 kHz and of acoustic pressure level 80 dB. When the negative capacitor in the system was properly adjusted, the acoustic pressure level of the transmitted sound was reduced from the initial 60 dB to 15 dB by the action of the negative capacitor. Then the system was exposed to naturally changing operational conditions, and their effect on sound-shielding efficiency was studied. It is shown that the acoustic transmission loss of the system dropped by 35 dB within 30 min from the moment of negative capacitor adjustment. Therefore, a self-adjustment of the system has been implemented by appending an additional digital control circuit to the negative capacitor. It is shown that the aforementioned deteriorating effect has been eliminated by the adjusting action of the control circuit. The long-time sustainable value of 60 dB in the acoustic transmission loss of the adaptive sound shielding system has been achieved.
Tomás Sluka; Hidekazu Kodama; Eiichi Fukada; Pavel Mokrý
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  IEEE transactions on ultrasonics, ferroelectrics, and frequency control     Volume:  55     ISSN:  1525-8955     ISO Abbreviation:  IEEE Trans Ultrason Ferroelectr Freq Control     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-11-06     Completed Date:  2009-01-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882735     Medline TA:  IEEE Trans Ultrason Ferroelectr Freq Control     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1859-66     Citation Subset:  IM    
Inst. of Mechatron. & Comput. Eng., Tech. Univ. of Liberec, Liberec.
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MeSH Terms
Acoustics / instrumentation*
Electric Capacitance*
Energy Transfer
Equipment Design
Equipment Failure Analysis
Radiation Protection / instrumentation*,  methods

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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