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Conference Paper: Control of weak perturbations

TitleControl of weak perturbations
Authors
KeywordsPhysics
Sound
Issue Date2012
PublisherAcoustical Society of America. The Journal's web site is located at http://asa.aip.org/jasa.html
Citation
The ACOUSTICS 2012 HONG KONG Conference and Exhibition, Hong Kong, 13-18 May 2012. In Journal of the Acoustical Society of America, 2012, v. 131 n. 4, pt. 2, p. 3430-3430, abstract 4aHT8 How to Cite?
AbstractWe define sound as being a weak perturbation in the properties of material consistent with the Navier-Stokes and continuity equations. Lighthill’s pioneering paper on aerodynamic noise gives an exact theory that enables interesting connections to be made between flow and sound. Aerodynamic noise being caused by quadrupoles is a good point of view, but what caused the quadrupoles? Were they possibly initiated by sound? Conclusions deduced from such a theory are not necessarily helpful, but they are true and might be very helpful indeed. The linear perturbations we call sound obey linear rules and it can be suppressed by anti-sound, a subject now becoming both practical and useful. The same must apply to any weak perturbation of a dynamic system perturbed from rest. Some perturbations are unstable and grow exponentially in their early weak state. They might be eliminated altogether by suppressing their linear form. The Rijke tube experiment shows that to be practical and shows also the close similarity that exists between acoustics and control theory. The lecture will give more examples of that type and suggest others that have yet to be demonstrated.
DescriptionSession 4aHT - Hot Topics: Aeroacoustics I: abstract 4aHT8
Starting from p. 3207 of this journal issue is proceedings of ACOUSTICS 2012 HONG KONG
Persistent Identifierhttp://hdl.handle.net/10722/160281
ISSN
2015 Impact Factor: 1.572
2015 SCImago Journal Rankings: 0.938

 

DC FieldValueLanguage
dc.contributor.authorFfowcs Williams, JEen_US
dc.contributor.authorHuang, Len_US
dc.date.accessioned2012-08-16T06:07:32Z-
dc.date.available2012-08-16T06:07:32Z-
dc.date.issued2012en_US
dc.identifier.citationThe ACOUSTICS 2012 HONG KONG Conference and Exhibition, Hong Kong, 13-18 May 2012. In Journal of the Acoustical Society of America, 2012, v. 131 n. 4, pt. 2, p. 3430-3430, abstract 4aHT8en_US
dc.identifier.issn0001-4966-
dc.identifier.urihttp://hdl.handle.net/10722/160281-
dc.descriptionSession 4aHT - Hot Topics: Aeroacoustics I: abstract 4aHT8-
dc.descriptionStarting from p. 3207 of this journal issue is proceedings of ACOUSTICS 2012 HONG KONG-
dc.description.abstractWe define sound as being a weak perturbation in the properties of material consistent with the Navier-Stokes and continuity equations. Lighthill’s pioneering paper on aerodynamic noise gives an exact theory that enables interesting connections to be made between flow and sound. Aerodynamic noise being caused by quadrupoles is a good point of view, but what caused the quadrupoles? Were they possibly initiated by sound? Conclusions deduced from such a theory are not necessarily helpful, but they are true and might be very helpful indeed. The linear perturbations we call sound obey linear rules and it can be suppressed by anti-sound, a subject now becoming both practical and useful. The same must apply to any weak perturbation of a dynamic system perturbed from rest. Some perturbations are unstable and grow exponentially in their early weak state. They might be eliminated altogether by suppressing their linear form. The Rijke tube experiment shows that to be practical and shows also the close similarity that exists between acoustics and control theory. The lecture will give more examples of that type and suggest others that have yet to be demonstrated.-
dc.languageengen_US
dc.publisherAcoustical Society of America. The Journal's web site is located at http://asa.aip.org/jasa.html-
dc.relation.ispartofJournal of the Acoustical Society of Americaen_US
dc.rightsJournal of the Acoustical Society of America. Copyright © Acoustical Society of America.-
dc.rightsCopyright 2012 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in Journal of the Acoustical Society of America, 2012, v. 131 n. 4, pt. 2, p. 3430-3430, abstract 4aHT8 and may be found at http://dx.doi.org.eproxy1.lib.hku.hk/10.1121/1.4708867.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectPhysics-
dc.subjectSound-
dc.titleControl of weak perturbationsen_US
dc.typeConference_Paperen_US
dc.identifier.emailHuang, L: lixi@hku.hken_US
dc.identifier.authorityHuang, L=rp00119en_US
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1121/1.4708867-
dc.identifier.hkuros203572en_US
dc.identifier.volume131en_US
dc.identifier.issue4, pt. 2en_US
dc.identifier.spage3430en_US
dc.identifier.epage3430en_US
dc.publisher.placeUnited States-
dc.customcontrol.immutablesml 140117-

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