Abstract: As disclosed herein, methods of forming piezoelectric layers having alternating polarizations and related bulk acoustic wave filter devices. Pursuant to these embodiments, a method of forming a piezoelectric resonator device can include forming a first material, including metal and nitrogen atoms, using a first process to provide a first piezoelectric layer having the metal and the nitrogen atoms arranged in a first polar orientation, to establish a first polarization for the first piezoelectric layer and forming a second material, including the metal and the nitrogen atoms on the first piezoelectric layer, using a second process to provide a second piezoelectric layer having the metal and the nitrogen atoms arranged in a second polar orientation, to establish a second polarization for the second piezoelectric layer that is opposite of the first polarization.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise comprises: (i) at least one tube having an inlet end, an outlet end and a central tube portion therebetween; and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one tube having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.

Abstract: An aircraft engine nacelle comprises: (a) an inlet lip and a skin having internal and external surfaces; (b) a noise abatement structure such as an acoustic panel located on the internal surface of the nacelle skin; and (c) an electrically powered de-icing system located on the external surface of the nacelle skin and in electrical connection to a power source. A method for de-icing and abating noise from an aircraft nacelle comprises: (a) providing a noise abatement structure such as an acoustic panel located on the internal surface of the nacelle skin; (b) providing an electrically powered de-icing system on the external surface of the nacelle skin; and (c) applying an electric current to the electrically powered de-icing system. The nacelle skin may be a perforated skin, and the de-icing system comprises a wire mesh bonded to the external surface of the perforated skin.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise (730) comprises: (i) at least one tube “H-Q” having an inlet end (738), an outlet end (740) and a central tube portion therebetween; and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.