Abstract: An acoustic system is provided for the perfect absorption of bending waves. The acoustic system includes a longitudinally extending substrate (plate or beam) defining upper and lower opposing major surfaces. At least two mechanical resonators are coupled to the upper major surface and separated by a distance dimension that may be based on a fraction of a magnitude of the wavelength of a selected bending wave. Each mechanical resonator includes a rigid mass component and a connecting element. The mechanical resonators are configured to block or absorb bending waves that propagate through the substrate. The connecting elements maintain the rigid mass component an elevated distance from the upper major surface of the beam when in a rest position. The connecting element can be a spring and damper; a flexible rubber/plastic component with an axial stiffness; or a base connecting component with a flexible arm, optionally with vibration damping.

Abstract: Systems for building modular quarter-wavelength resonators, and arrays of said resonators, include interlocking blocks having channels in them. Different block varieties can include those having straight channels and those having curved channels, to facilitate assembly of resonators of any desired configuration. Resonator length, and therefore resonance frequency, can be easily designed by adjusting the number of blocks used for a particular resonator.

Abstract: A thermal management assembly is provided for both removing heat and absorbing acoustic energy. The thermal management assembly includes a heat sink base component and a plurality of thermally conductive fins disposed in a sparsely-arranged array in thermal communication with the heat sink base component. Each fin defines a two-sided Helmholtz unit cell disposed in a periodic array extending from the heat sink base component. Each unit cell includes a lossy resonator and a lossless resonator. The lossy resonator includes a first chamber portion bounded by at least one first boundary wall defining a first chamber volume, and a first neck forming an opening in the first chamber portion. The lossless resonator includes a second chamber portion bounded by at least one second boundary wall defining a second chamber volume, and a second neck forming an opening in the second chamber portion.

Abstract: A broadband sparse acoustic reflector includes a periodic array of laterally spaced apart unit cells, each unit cell having a plurality of longitudinally positioned Helmholtz resonators. Each unit cell includes a Helmholtz resonator having a neck that places the resonator interior in fluid communication with an ambient fluid, in the lateral direction. Each Helmholtz resonator of the unit cell has a different resonance frequency, providing broadband reflection.

Abstract: A system for actively mitigating a buffeting noise in an occupant compartment of a vehicle when the vehicle is moving. The system is configured to determine an estimated effective volume of the occupant compartment, and to determine if a single window of the vehicle occupant compartment is open. Responsive to a determination that a single window of the vehicle occupant compartment is open, and using the estimated effective volume of the occupant compartment, an estimated buffeting noise frequency is determined. Responsive to the estimated buffeting noise frequency, the system determines characteristics of a sound configured to cancel a buffeting noise generated inside the occupant compartment while the vehicle is moving. The system may then control operation of a noise cancelling signal generating system to generate the sound having characteristics configured to cancel the buffeting noise inside the occupant compartment.

Abstract: Systems for magnetoacoustically transferring sound across an acoustic barrier include first and second acoustic resonators positioned on opposite sides of the barrier. Each of the first and second resonators includes an attached magnet. Via magnetic coupling between the magnets, an acoustic oscillation at the first resonator induces an oscillation of the same frequency at the second resonator. Thus sound waves absorbed at the first resonator are magnetically transferred across the barrier to the second resonator, from which they are emitted.

Abstract: Passively controlled acoustic metamaterials allow transmission of low amplitude acoustic (sound) waves having a resonance frequency and reflect waves having a substantially different frequency. Such materials also reflect waves having the resonance frequency when those waves have an amplitude exceeding a threshold. High amplitude resonance waves cause a resonance membrane contained in unit cells of the metamaterial to contact a rigid structure that is positioned at a longitudinal constraint distance from the resonance membrane in each unit cell. Such contact changes the resonance frequency of the membrane, thereby causing reflection of high amplitude waves. Actively controlled acoustic metamaterials include a ferromagnetic layer on the membrane and an electromagnetic positioned in each unit cell. Activation of the electromagnetic displaces the membrane and thereby shifts the resonance frequency of the membrane, on demand.

Abstract: Sound direction detection devices include cylinders or other longitudinally extended structures having rotational symmetry about their longitudinal axes and multiple, rotationally equivalent resonators contained therein. Each resonator contains a microphone or other transducer that is activated when the resonator resonates.

Abstract: Compact sound attenuation systems for fluid ducts are provided having one or more sound attenuation units that can be absorptive or reflective, depending on design. Each sound attenuation unit has one or more encircling Helmholtz resonators that fully encircle the duct in a lateral direction. Sound attenuation units can be coincident with the duct well and either interior or exterior to the duct, or in some instances can be partly interior and partly exterior to the duct. Sound attenuation systems can be tuned for maximum attenuation of a single resonance frequency, or can include multiple units of different frequencies for broadband attenuation.

Abstract: A shaped acoustic absorber assembly is provided with broadband absorption. The assembly includes an acoustic panel defining a plurality of apertures, and a plurality of tubular quarter-wavelength resonators of variable lengths provided respectively aligned with the plurality of apertures and coupled to the acoustic panel. Each tubular quarter-wavelength resonator includes at least one perimeter boundary wall extending in a longitudinal length direction and defining a chamber cavity having a chamber volume. A first end defines an opening aligned with one of the plurality of apertures and coupled to the acoustic panel. A second end is provided opposite the first end, and is sealed and configured for being located adjacent a target substrate. Methods are provided for shaping the tubular quarter-wavelength resonators to coordinate with a geometry and dimensions of a target substrate and then preserving a shape of the tubular quarter-wavelength resonators in a structurally rigid configuration.

Abstract: Embodiments described herein generally relate to a multi-mode heat transfer system. The heat transfer system includes an emitter device. The emitter device includes an inner core surrounded by an outer core having a thickness and an outer surface. A composite material pattern extends through at least a portion of the outer surface and at least a portion of the thickness of the outer core and is thermally coupled to the inner core. The composite material pattern in combination with an optimized emissivity surface coating/paint profile directs a heat from the inner core to an object other than the emitter device.

Abstract: A membrane-type acoustic absorber structure is provided for an acoustic panel. The absorber structure includes an acoustic substrate. A plurality of spaced apart unit cells are provided in the acoustic substrate and arranged in a periodic array. Each unit cell includes at least one perimeter boundary wall and a bottom wall portion. The perimeter boundary wall and bottom wall portion cooperate to define a chamber with an opening and a chamber cavity having a chamber volume. An elastic membrane is disposed at the chamber opening and configured for sealing the chamber cavity. At least one lossy porous medium is provided aligned with, and separated a distance from, the elastic membrane. A fluid/gas is provided in the chamber volume. In certain aspects, the unit cells may have identical dimensions, having the same resonance frequency. In other aspects, the unit cells may have different dimensions, providing a broadband absorber.

Abstract: Sound absorption units for fluid ducts include two acoustically coupled pairs of Helmholtz resonators. The two resonators within each pair have identical resonance frequency, however the upstream resonator within each pair is partly filled with an acoustically lossy porous material, so that the upstream resonator within each pair has greater acoustic loss than its coupled downstream resonator. The upstream pair of resonators has a relatively low resonance frequency, while the downstream pair of resonators has a relatively high resonance frequency. The combination of frequency mismatch between the resonator pairs, and loss mismatch within each resonator pair, produces consistently high sound absorption across a broad frequency spectrum.

Abstract: A system for determining at least one characteristic of a transmitting coil generating a magnetic field may include a first measurement coil being wound in a first direction, a second measurement coil being wound in a second direction, a voltage measuring device, and at least one processor in communication with the voltage measuring device. The first measurement coil and the second measurement coil may be adjacent to one another. The voltage measuring device may be configured to measure a first voltage of the first measurement coil and a second voltage of the second measurement coil in response to the magnetic field generated by the transmitting coil. The at least one processor may be configured to determine the at least one characteristic of the transmitting coil based on a ratio between the first voltage and the second voltage at a predetermined frequency.

Abstract: Systems, methods, and other embodiments described herein relate to a drone having selectively actuated arms. In one embodiment, a drone includes arms connected to a body. Individual ones of the arms have a first end and a second end with the first end forming a connection with the body. The drone further includes rotor units individually including a propeller attached to a motor and mounted to the second end of the individual ones of the arms. Additionally, actuator units are integrated with the arms. Individual ones of the actuator units include electromagnetic cells that when activated induce an electromagnetic motive force that flexes the arms.

Abstract: A sparse acoustic absorber includes a periodic array of spaced apart unit cells, generally having a lateral fill factor less than 0.5. Each unit cell includes a pair of joined, and inverted, Helmholtz resonators, having neck portions that point in opposite directions. This structure enables ambient fluid, such as air, to pass through the absorber. The absorber predominantly absorbs acoustic waves having a resonant frequency when such waves are incident on the absorber in one direction, and predominantly reflect such waves when they are incident on the absorber in the opposite direction. Dual-function sound suppression systems incorporate such an absorber into a porous substrate, such as a wire mesh, that enables fluid to pass and alternatively absorbs or reflects sound.

Abstract: Acoustic measurement systems include an enclosure having a high efficiency yet very thin acoustic absorber coating portions thereof, in order to diminish background reflections. The thin acoustic absorber includes a reflective sublayer having a periodic array of indentations on its surface. The periodic array of indentations can be one-dimensional or two dimensional. The thin acoustic absorber further includes a thin absorbing layer overlaid on the reflective sublayer, and typically formed of a viscoelastic foam. The thin acoustic absorber possesses unprecedented absorption efficiency across a broad frequency range and at normal or oblique angles of incidence.

Abstract: Sound direction detection devices include cylinders or other longitudinally extended structures having rotational symmetry about their longitudinal axes and multiple, rotationally equivalent resonators contained therein. Each resonator contains a microphone or other transducer that is activated when the resonator resonates.

Abstract: An invisible sound barrier includes a periodic array of spaced apart, columnar unit cells. Each unit cell includes a pair of joined, and inverted, columnar Helmholtz resonators, having neck portions that point in opposite directions. Each of the Helmholtz resonators can be formed of a sound absorbing material and coated with a light reflective material causing light to reflect around the resonators, thereby conferring invisibility. Each of the Helmholtz resonators can alternatively be formed of a light reflecting material, and positioned in between vertical mirrors, with a transparent material filling space between the resonators and the vertical mirrors.

Abstract: Embodiments described herein relate to an adaptable photonic apparatus including an optical neural network. The photonic apparatus includes an optical input that provides an optical signal. The photonic apparatus also includes a chassis component and an optical neural network (ONN). The chassis component includes at least one modular mounting location for receiving a modular network component. The ONN is operably connected with the optical input and is configured to perform optical processing on the optical signal according to a deep learning algorithm. The ONN includes optical components arranged into layers to form the ONN. The modular network component is an additional optical processing component that is configured to function in cooperation with the ONN to adapt the deep learning algorithm.