BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Inverse Source Problems of Active Sound Control for Composite Doma
 ins - Utyuzhnikov\, SV (University of Manchester)
DTSTART:20111215T103000Z
DTEND:20111215T110000Z
UID:TALK34978@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:In the active noise shielding problem\, a quite arbitrary doma
 in (bounded or unbounded) is shielded from the field (noise)\, generated o
 utside\, via introducing additional sources. Along with noise\, the presen
 ce of internal (wanted) sound sources is admitted. Active shielding is ach
 ieved by constructing additional (secondary) sources in such a way that th
 e total contribution of all sources leads to the noise attenuation. In con
 trast to passive control\, there is no any mechanical insulation in the sy
 stem. In practice\, active and passive noise control strategies could ofte
 n be combined\, because passive insulation is more efficient for higher fr
 equencies\, whereas active shielding is more efficient for lower frequenci
 es. \n\nThe problem is formulated as an inverse source problem with the se
 condary sources positioned outside the domain to be shielded. The solution
  to the problem is obtained in both the frequency and time domains\, and b
 ased on Calderόn  Ryabenkiis surface potentials [1]. A key property of th
 ese potentials is that they are projections. The constructed solution to t
 he problem requires only the knowledge of the total field at the perimeter
  of the shielded domain [1-3]. In practice\, usually the total field can o
 nly be measured. The methodology automatically differentiates between the 
 wanted and unwanted components of the field. A unique feature of the propo
 sed methodology is its capability to cancel the unwanted noise across the 
 volume and keep the wanted sound unaffected. It is important that the tech
 nique requires no detailed information of either the properties of the med
 ium or the noise sources. \n\nThe technique can also be extended to a comp
 osite protected region (multiply connected) [4]. Moreover\, the overall do
 main can arbitrarily be split into a collection of subdomains\, and those 
 subdomains are selectively allowed to either communicate freely or otherwi
 se be shielded from their peers. In doing so\, no reciprocity is assumed\,
  i.e.\, for a given pair or subdomains one may be allowed to hear the othe
 r\, but not vice a versa. Possible applications of this approach to engine
 ering problems such as oil prospecting are discussed. \n
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR