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: System, methods, and other embodiments described herein relate to tuning an absorption system based on an exceptional point for a shunted mechanical resonator of the absorption system. In one embodiment, the absorption system includes a first mechanical resonator having a beam connected to a body that is subject to a flexural wave. The first mechanical resonator has a latent absorption. The absorption system includes a first electrical resonator that includes a piezoelectric device, bonded to the beam, that generates electricity in response to the flexural wave propagating through the body. The absorption system also includes a shunting circuit connected to the piezoelectric device and tuned based on a calculated exceptional point for the absorption system. The shunting circuit alters an absorption of the first mechanical resonator and controls a voltage and current shunted to the piezoelectric device to absorb the flexural wave.

Abstract: System, methods, and other embodiments described herein relate to absorbing flexural waves. In one embodiment, a system includes a longitudinally extending body that is subject to a flexural wave and a bandpass filter. The bandpass filter transmits a target flexural wave having a particular wavelength and blocks a non-target flexural wave. The bandpass filter includes at least two mechanical resonators coupled to a surface of the longitudinally extending body and aligned in a first linear array along a length dimension of the longitudinally extending body. The at least two mechanical resonators of the first linear array are separated by a distance based on the particular wavelength.

Abstract: System, methods, and other embodiments described herein relate to a high-Q resonant state embedded system in a continuous body. In one embodiment, a system includes a longitudinally extending body that is subject to a flexural wave. The longitudinally extending body is attached to a fixed structure at a first end. The system also includes a mechanical resonator coupled to a surface of the longitudinally extending body along a length dimension of the longitudinally extending body. The mechanical resonator is located at a distance away from a second end of the longitudinally extending body to exhibit an infinite Q factor based on physical properties of the mechanical resonator.

Abstract: A system can be configured to harvest energy from sound waves. The system can include a resonator and an acoustic energy harvester located in the resonator. The acoustic energy harvester can be configured to convert acoustic energy into electrical energy. In some instances, the resonator can be a central resonator, and a plurality of surrounding resonators can be arrayed about the central resonator. The surrounding resonators do not include an acoustic energy harvester.

Abstract: A multi-mode heat transfer system includes an emitter device with an inner core surrounded by an outer core having an outer surface and an emission surface disposed on the outer surface. The emission surface includes a thermal metamaterial configured to direct heat from the inner core in at least two desired directions to an object other than the emitter device. The object can include a thermal receiver devices, for example two receiver devices and the emission surface can direct heat to two different receiver devices spaced apart from the emitter device.

Abstract: Thermophotovoltaic (TPV) systems for energy harvesting with thermal management are provided. The systems include a three-dimensional architected wick having a porous structure for delivering a two-phase working fluid via capillary action to maintain efficient cooling of a TPV cell array. The wick is configured to uniformly deliver working fluid for evaporative cooling of the TPV cells. The wick may be in direct thermal communication with the TPV cell or employed to locally deliver working fluid to an evaporator that is in direct thermal communication with the TPV cell. The increased surface area of porous structure of the wick and the evaporator increases heat dissipation and evaporative cooling providing an improvement in temperature distribution and heat transfer critical to maintaining the TPV cell at a constant temperature.

Abstract: A light-activated acoustic resonator and associated methods are described herein. One embodiment measures the level of ambient light in the environment of the light-activated acoustic resonator; causes a moveable member of an electromagnet disposed within a Helmholtz resonator of the light-activated acoustic resonator to be in an extended position that places the Helmholtz resonator in a first acoustic state, when the level of ambient light is less than a predetermined amount; and causes the moveable member to be in a retracted position that places the Helmholtz resonator in a second acoustic state different from the first acoustic state, when the level of ambient light is at least the predetermined amount.

Abstract: System, methods, and other embodiments described herein relate to tuning a mechanical resonator for detecting a significant value using an electrical resonator that enhances sensitivity. In one embodiment, a system includes a mechanical resonator having a beam coupled to a body. The system also includes an electrical resonator coupled through a patch to the mechanical resonator, the electrical resonator operating as a shunt and having an inductor and a resistor (LR) circuit in series. The system also includes the electrical resonator that detects, associated with a perturbation of the body, an exceptional point (EP) of the mechanical resonator by varying the LR circuit according to a model.

Abstract: Systems described herein relate to sensing pressure. In one arrangement, a pressure sensor is disclosed. The pressure sensor includes a circuit including a resistor, an inductor, and a capacitor. The circuit generates an electrical resonance. The resistor is an elastomer having a resistance and connected to an outer surface of an inflatable. The pressure sensor also includes a resonator connected to the circuit. The resonator generates a mechanical resonance coupling with the electrical resonance to create a detuning frequency having a sublinear dependence on the resistance of the elastomer. A pressure of the inflatable correlates with the detuning frequency.

Abstract: A device for superscattering a target acoustic wave may include a body having an outer surface, at least one resonator being defined within the body and extending to an opening defined within the outer surface and configured to cause the superscattering of the target acoustic wave impinging upon the body, and a motor connected to the body and configured to selectively rotate the body.

Abstract: Thermophotovoltaic (TPV) systems for energy harvesting with thermal management are provided. The systems include a three-dimensional architected wick having a porous structure for delivering a two-phase working fluid via capillary action to maintain efficient cooling of a TPV cell array. The wick is configured to uniformly deliver working fluid for evaporative cooling of the TPV cells. The wick may be in direct thermal communication with the TPV cell or employed to locally deliver working fluid to an evaporator that is in direct thermal communication with the TPV cell. The increased surface area of porous structure of the wick and the evaporator increases heat dissipation and evaporative cooling providing an improvement in temperature distribution and heat transfer critical to maintaining the TPV cell at a constant temperature.

Abstract: Systems, apparatuses, and methods provide for measuring elastic modulus usable with a tubular object. A sound signal is propagated within the tubular object via a speaker coupled to a proximal end of an impedance tube. The propagated sound signal is measured within the tubular object via a pair of microphones coupled to the impedance tube. An elastic modulus of the tubular object is determined in response to the measurement of the propagated sound signal.

Abstract: The direction of an acoustic wave can be determined using a single microphone. The single microphone can be operatively positioned within an interior of a resonator. The resonator can include a body that includes an aperture, such as a slit, which allows communication between the interior and an exterior of the resonator. The resonator can be configured to rotate. The single microphone can be configured to acquire sound data of an incident acoustic wave. One or more processors can be operatively connected to the single microphone. The one or more processors can be configured to determine a direction of the incident acoustic wave based on the acquired sound data.

Abstract: An energy harvesting system capable of using vibrational or mechanical energy to direct energy along a line to an energy receiver to transfer the vibrational energy. The energy harvesting system includes an energy transmitter capable of turning rotational or vibrational energy into a linear vibration that travels along the line to an energy receiver that takes the vibrational energy stored in the transverse wave and turns it into rotational motion. The rotational motion can then be used to drive an electric generator. A tension control unit provides tension to the line ensuring the amplitude of the transverse wave is at a maxima when it reaches the energy receiver.

Abstract: A thermal diode includes: a dielectric enclosure having a top surface, a bottom surface, a first side, and a second side; a first Weyl semimetal nanoparticle disposed on the first side; a second Weyl semimetal nanoparticle disposed on the second side; a nanograting disposed on the bottom surface; and a voltage source configured to provide a voltage bias to the nanograting to suppress surface waves from the first Weyl semimetal nanoparticle to the second Weyl semimetal nanoparticle and to modify surface waves from the second Weyl semimetal nanoparticle to the first Weyl semimetal nanoparticle.

Abstract: A multi-mode heat transfer system includes an emitter device with an inner core surrounded by an outer core having an outer surface and an emission surface disposed on the outer surface. The emission surface includes a thermal metamaterial configured to direct heat from the inner core in at least two desired directions to an object other than the emitter device. The object can include a thermal receiver devices, for example two receiver devices and the emission surface can direct heat to two different receiver devices spaced apart from the emitter device.

Abstract: A duct includes a duct body defining an inlet, an outlet, and a channel connecting the inlet and the outlet. The duct body also defines an upstream resonator. The upstream resonator includes an upstream annular cavity external to the channel and an annular perforated plate coplanar with the upstream annular cavity. The duct body further defines a downstream resonator. The downstream resonator includes a downstream annular cavity external to the channel and an annular neck coplanar with the downstream annular cavity.

Abstract: A sound absorbing device includes a panel with an opening, a duct extending from the panel and in fluid communication with the opening, and a plurality of acoustic resonators embedded in the panel and in fluid communication with the duct. The duct can have a rectangular cuboid shape and the plurality of acoustic resonators can include a first subset of quarter-wavelength tubes extending from a first planar side of the duct, a second subset of quarter-wavelength tubes extending from a second planar side of the duct, a third subset of quarter-wavelength tubes extending from a third planar side of the duct, and a fourth subset of quarter-wavelength tubes extending from a fourth planar side of the duct. Also, the second subset of quarter-wavelength tubes and the fourth subset of quarter-wavelength tubes can have mirror symmetry with the first subset of quarter-wavelength tubes and the third subset of quarter-wavelength tubes, respectively.

Abstract: Systems and methods for determining the incident angle of an acoustic wave are presented herein. One embodiment receives an acoustic wave at N transducers, where N is a natural number greater than or equal to 2; solves a set of N coupled differential equations modeling a set of N virtual coupled acoustic resonators using N coupled analog circuits, wherein each of the N coupled analog circuits receives an output signal from a unique one of the N transducers and outputs a voltage signal; and analyzes the N voltage signals output by the N coupled analog circuits to produce an estimate of the incident angle of the acoustic wave.