Abstract: A flexural wave absorption system detects, with a sensor attached to a beam, an incident wave propagating in the beam. The system determines, based on a signal from the sensor generated in response to the incident wave, an amplitude and phase of the incident wave propagating in the beam and controls an actuator connected to the beam to generate a suppression wave, based on the amplitude and the phase of the incident wave, that reduces a coefficient of reflection of the incident wave across a broadband frequency range.

Abstract: Frequency adjustable quarter-wavelength resonators have a movable end wall defined by a surface of a sphere that is moved within the resonator tube. The sphere can be ferromagnetic, enabling it to be moved by magnetic interactions with moving external magnetic elements, or by a variable external magnetic field, controlled by power modulation to external electromagnets. The resonators can optionally be helical or otherwise curved, and the spherical shape of the structure forming the end wall enables it to navigate curves in the resonator tube.

Abstract: Embodiments described herein relate to a bi-functional thermal cooling system. The bi-functional thermal cooling system includes a first body, a second body, and a third body. The second body has a first plurality of Weyl semimetal nanostructures. The second body is spaced apart from the first body. The third body has a second plurality of Weyl semimetal nanostructures. The third body is spaced apart from the second body. The second body and the third body are each configured to independently rotate with respect to the first body to change an optical property of the first plurality of Weyl semimetal nanostructures of the second body and an optical property of the second plurality of Weyl semimetal nanostructures of the third body.

Abstract: Embodiments described herein relate a tunable heat transfer system. The tunable heat transfer system includes a controller, a first body, and a second body. The first body is communicatively coupled to the controller. The second body is communicatively coupled to the controller and spaced apart from the first body. The second body has a plurality of semimetal layers and a dielectric portion positioned between each of the plurality of semimetal layers. Each of the dielectric portions has a thickness to define a gap between each the plurality of semimetal layers in an expanded state and permitting each of the plurality of semimetal layers to abut each other in a contracted state. The controller is configured to change a near-field radiative heat transfer between the first body and the second body by changing the thickness of each of the dielectric portions between the expanded state and the contracted state.

Abstract: An acoustic imaging metamaterial is provided for obtaining edge detection information of a tangible object. The acoustic imaging metamaterial includes a longitudinally extending phononic crystal substrate that defines a first major surface and a second major surface opposite the first major surface. A first structurally rigid grating layer is disposed adjacent the first major surface, and a second structurally rigid grating layer is disposed adjacent the second major surface. In various aspects, the first and second structurally rigid grating layers are identical in shape and dimensions, and are aligned with one another. The acoustic imaging metamaterial is configured to redirect, confine, and/or manipulate an incident acoustic wave resulting in a high contrast image used for extracting edge detection information of the tangible object. The background medium fluid of the system can be air or a fluid such as water.

Abstract: A tunable metamaterial structure can have a flexible substrate that is elastically deformable. The tunable metamaterial structure can have a photo-responsive stiffness-modulating patch. The photo-responsive stiffness-modulating patch can be fixed to a surface of the flexible substrate. The photo-responsive stiffness-modulating patch can include a piezoelectric element and a photo-responsive element. The piezoelectric element and the photo-responsive element are electrically connected to one another.

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: 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: 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 system can improve the performance of an electroacoustic absorber. The system includes a loudspeaker and an absorber operatively positioned relative to the loudspeaker. The absorber can be configured to absorb sound waves. A control circuit can be operatively connected to the loudspeaker. The control circuit can be configured to tune the resonance of the loudspeaker and therefore cause one or more acoustic characteristics, such as acoustic impedance, of the loudspeaker to be adjusted.

Abstract: Devices for detecting plate bending, or flexural, waves include at least two mechanical resonators positioned on a plate in a specified configuration. Each mechanical resonator has an associated oscillation amplitude detector, such as a laser vibrometer, configured to detect resonant oscillation of the mechanical resonator in response to an incident flexural wave. A ratio of frequency-dependent oscillation data for each mechanical oscillator is compared to a calibration curve to determine the angle of incidence of the flexural wave.

Abstract: An acoustic impedance matching device can facilitate acoustic transmission across an interface formed by materials having a very large acoustic impedance mismatch (e.g. air-water, or air-elastic polymer). The device can include a first medium. The first medium can have a first acoustic impedance. The device can include a second medium. The second medium can have a second acoustic impedance. The second acoustic impedance can be substantially greater than the first acoustic impedance. Thus, the first acoustic impedance and the second acoustic impedance are substantially mismatched. An interface can be defined between the first medium and the second medium. A bubble can be located in the second medium or the interface. The bubble can act as a resonator and can enable efficient sound transmission despite the large impedance mismatch of the first medium and the second medium.

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: Embodiments described herein relate to a photonic apparatus for processing optical signals within an integrated optical pathway. The photonic apparatus a light perception device that perceives light from a surrounding environment of the apparatus. The photonic apparatus also includes an optical neural network (ONN) connected with the light perception device via an optical relay. The optical neural network configured to perform optical processing on the light according to a deep learning algorithm and using optical components.

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 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: 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: Airborne acoustic absorbers include periodic arrays of Helmholtz resonators that are covered and/or partially filled with an acoustically absorptive material, such as a thermoplastic foam. The combined structures have much broader frequency ranges of high acoustic absorption than do structures having only Helmholtz resonators or acoustically absorbing foam.

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 relate to a device for detecting the position of electromagnetic noise. The device includes a detector that includes coils that produce voltages in the presence of electromagnetic noise of a defined frequency. The device further includes a controller that senses the voltages and determines a position of the electromagnetic noise relative to the device according to the voltages.