CONSTRAINED OPTIMIZATION OF ACTIVE NOISE-CONTROL SYSTEMS IN ENCLOSURES

An effective software design tool is proposed for solving active noise control problems associated with constraints in which the complex str ength and location of the secondary source of an active noise control system in an enclosed space are simultaneously optimized. The boundary element method is adopted to evaluate the sound field in enclosures. Furthermore, the boundary used could be of pressure, velocity, or impe dance; in addition, the primary source may be at an arbitrary position . An optimizer based on sequential quadratic programming is selected f or its accuracy, efficiency, and reliability. Bounds for design variab les and proper constraints on the sound field and secondary source can be specified as required. The powerfulness of the proposed tool is de monstrated by optimizing an active control system for an enclosure. Fo r a rectangular cavity, the optimal location of the secondary source i s confirmed by observed simulations as always forming a dipole with th e primary source situated at off-resonance excitations and subsequentl y approaching a mirror image position of the primary source at resonan ce excitations. The optimal location of the controller is found to cha nge with varied upper bounds of the strength of the secondary source. These findings show a discrepancy from those reported in previous rese arches based on an unconstrained formulation. Sensitivity analysis at the optimum is also included to provide information of practical conce rn for implementing optimized active noise control systems.