Abstract: Acoustic diodes, devices incorporating such diodes and methods of using such devices are disclosed. An acoustic diode may include a periodic acoustic grating and a uniform plate. The periodic acoustic grating may include a plurality of gratings. The uniform plate may foe separated from the periodic acoustic grating by a resonant cavity. The acoustic diode may be configured to have a first transmission efficiency for acoustic waves incident on the periodic acoustic grating that is greater than a second transmission efficiency for acoustic waves incident on the uniform plate. The acoustic waves may have a wavelength within a range of wavelengths. Devices incorporating the acoustic diode may include medical imaging devices, such as ultrasound devices, and noise reduction devices.

Abstract: Systems and methods are disclosed for removing nano-particulates from a gas. The systems may include a chamber to contain the particulate-containing gas, a source of the gas, a source of water vapor, a source of a supersonic gas, and at least one ultrasonic transducer in contact with the chamber. The chamber may also include one or more receptacles to receive the particulates. The methods may include introducing the particulate-containing gas and the water vapor into the chamber. A gas may be introduced into the chamber at supersonic speeds thereby cooling the water vapor to form nucleating ice crystals. The ultrasonic transducers may then introduce ultrasonic power into the chamber thereby causing the particulates to contact the ice crystals. The nucleating crystals, with their attached particulates, may then fall under gravity to be captured in the receptacles.

Abstract: Acoustic diodes, devices incorporating such diodes; and methods of using such devices are disclosed. An acoustic diode may include a periodic acoustic grating and a uniform plate. The periodic acoustic grating may include a plurality of .gratings. The uniform plate may foe separated from-the periodic acoustic-grating by a resonant cavity. The acoustic diode may be configured to have a first transmission, efficiency for acoustic waves incident on the periodic acoustic grating that is greater than a second transmission efficiency for acoustic waves incident on the uniform plate. The acoustic waves may have a. wavelength within a range of wavelengths. Devices incorporating the acoustic diode may include medical imaging devices, such as ultrasound devices, and noise reduction devices.

Abstract: Systems and methods are disclosed for removing nano-particulates from a gas. The systems may include a chamber to contain the particulate-containing gas, a source of the gas, a source of water vapor, a source of a supersonic gas, and at least one ultrasonic transducer in contact with the chamber. The chamber may also include one or more receptacles to receive the particulates. The methods may include introducing the particulate-containing gas and the water vapor into the chamber. A gas may be introduced into the chamber at supersonic speeds thereby cooling the water vapor to form nucleating ice crystals. The ultrasonic transducers may then introduce ultrasonic power into the chamber thereby causing the particulates to contact the ice crystals. The nucleating crystals, with their attached particulates, may then fall under gravity to be captured in the receptacles.

Abstract: An acoustic diode includes a phononic crystal medium, a nonlinear acoustic medium, a aluminum tubes contain the phononic crystal medium and the nonlinear acoustic medium. The phononic crystal medium is fabricated by alternately laminating a water layers and a glass layers in a periodic manner.

Abstract: An acoustic diode includes a phononic crystal medium, a nonlinear acoustic medium, a aluminum tubes contain the phononic crystal medium and the nonlinear acoustic medium. The phononic crystal medium is fabricated by alternately laminating a water layers and a glass layers in a periodic manner.