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: 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: A system and method are provided for manufacturing a tower structure. Accordingly, one or more layers of a wall element are deposited with a printhead assembly. At least one recess is defined in the wall element. The recess(es) has a single, circumferential opening positioned along an inner reference curve or an outer reference curve of the wall element. The recess(es) also has a depth which extends in a radial direction and intersects a midline reference curve. A reinforcing element is placed entirely within the recess(es) at the midline reference curve.

Abstract: The present application presents novel systems and methods for tracking reinforcement member placement in an additively manufactured structure that are simple, accurate, non-labor-intensive, and cost-effective. The present application also presents a novel method of manufacturing a tower structure comprising: depositing, via an additive printing system, a first printed layer of a wall with a printhead assembly, the wall at least partially circumscribing a vertical axis of the tower structure; positioning a first reinforcement member on the first printed layer; depositing, via the additive printing system, a second printed layer of the wall with the printhead assembly on the first reinforcement member, the second printed layer configured to hold a second reinforcement member thereon; and determining, via an optical sensor of the additive printing system, a position for placing the second reinforcement member based on the first reinforcement member positioning.

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.

Abstract: An adaptive characteristic spectral line screening method and system based on atomic emission spectrum are provided, the method includes: using a set characteristic screening optimization method to perform a plurality of optimization rounds of characteristic screening, obtaining an initialized spectral dataset of each round of the characteristic screening and initialized characteristic population genes; obtaining an optimal characteristic population gene of each round by a set analysis method, a fitness function, and an iteration of a genetic algorithm; obtaining an optimized characteristic spectral information set when the plurality of optimization rounds reach set optimization rounds; performing combination statistics and discriminant analyses on the optimized characteristic spectral information set to complete an adaptive characteristic spectral line screening.

Abstract: Cementitious materials having high damage tolerance and self-sensing ability are described herein. These materials may replace conventional concrete to serve as a major material component for infrastructure systems with greatly improved resistance to cracking, reinforcement corrosion, and other common deterioration mechanisms under service conditions, and prevents fracture failure under extreme events. These materials can also be used for the repair, retrofitting or rehabilitation of existing concrete structures or infrastructure systems. Furthermore, these materials may offer capacity for distributed and direct sensing of cracking, straining and deterioration with spatially continuous resolution wherever the material is located, without relying on installation of sensors.

Abstract: A flexural wave absorber includes an L-shaped cantilever beam lossy acoustic black hole disposed on a surface of a mechanical structure and an L-shaped cantilever beam lossless acoustic black hole disposed on the surface and spaced apart from the L-shaped cantilever beam lossy acoustic black hole a predefined distance. The L-shaped cantilever beam lossy acoustic black hole and the L-shaped cantilever beam lossless acoustic black hole, in combination, are configured to asymmetrically absorb a plurality of different frequencies of flexural waves within at least a 2000 Hz frequency band acting on the mechanical structure. The L-shaped cantilever beam lossy acoustic black hole and the L-shaped cantilever beam lossless acoustic black hole can both include a projecting beam with an outer surface or an inner surface having power law profile.

Abstract: The present application presents novel systems and methods for tracking reinforcement member placement in an additively manufactured structure that are simple, accurate, non-labor-intensive, and cost-effective. The present application also presents a novel method of manufacturing a tower structure comprising: depositing, via an additive printing system, a first printed layer of a wall with a printhead assembly, the wall at least partially circumscribing a vertical axis of the tower structure; positioning a first reinforcement member on the first printed layer; depositing, via the additive printing system, a second printed layer of the wall with the printhead assembly on the first reinforcement member, the second printed layer configured to hold a second reinforcement member thereon; and determining, via an optical sensor of the additive printing system, a position for placing the second reinforcement member based on the first reinforcement member positioning.

Abstract: A flexural wave absorber includes a metasurface with an inner portion, an outer portion, and a plurality of beam strips extending between the inner portion and the outer portion. The metasurface also includes a plurality of coupled resonators disposed on the plurality of beam strips. The plurality of coupled resonators can include a lossy resonator and a lossless resonator, two lossy resonators and a lossless resonator, or a lossy resonator and two lossless resonators. In addition, each of the plurality of beam strips can have multiple pairs of coupled resonators disposed thereon that work at or absorb different frequency ranges.

Abstract: A sound absorbing device includes a chamber with an opening and at least one fabric layer extending across the opening. The at least one fabric layer extending across the opening is at least two fabric layers stacked relative to and in direct contact with each other, at least two fabric layers stacked relative to and spaced apart from each other by a predefined distance, at least one elastic fabric layer configured to vibrate independently from the chamber, or a three dimensional fabric layer. The at least two fabric layers stacked relative to and in direct contact with each other and the at least two fabric layers stacked relative to and spaced apart from each other by a predefined distance are configured to move relative to each other, and the at least one elastic fabric layer is configured to vibrate independently from the chamber.

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: Embodiments for one-way sound absorbing systems are described herein. In one example, a sound absorbing system includes a waveguide having open ends for receiving an incoming acoustic wave and wall portions defining a first port and a second port. A first electroacoustic absorber is mounted to the first port and is electrically connected to a shunting circuit, while a second electroacoustic absorber is mounted to the second port and is electrically connected to an open circuit. The sound absorption of the system is directional dependent.

Abstract: A sound absorber can include a housing including a back wall, a perimeter wall, and an interior wall that form cells having cavities. The sound absorber can also include a panel disposed on the housing that substantially faces the back wall and encloses the cavities of the cells. The panel can define groups of holes for each cell such that one group of holes extend though the panel to the cavity of one cell and another group of holes extend through the panel to the cavity of another cell.

Abstract: Described is a system for transmitting a flexural wave acting on one structure to another structure. In one example, a system includes a first structure having a first property and a first end and a second structure having a second property and a second end connected to the first end of the first structure. The first property is different from the second property and may be related to the material and/or geometric properties of the first and second structures. A mechanical resonator is connected to the first structure at a distance from the first end of about a quarter-wavelength of the frequency of a flexural wave acting on the first structure. The mechanical resonator matches a first mechanical impedance of the first structure to a second mechanical impedance of the second structure to allow high transmission of the flexural wave acting on the first structure to the second structure.

Abstract: A wave control system includes a substrate with a plurality of beams spaced apart from each other, a plurality of sensors disposed on the plurality of beams, a plurality of actuators disposed on the plurality of beams, a processor, and a memory communicably coupled to the processor. The memory stores machine-readable instructions that, when executed by the processor, cause the processor to determine a frequency of a fundamental incident wave propagating within and/or incident on the plurality of beams based on a plurality of signals from the plurality of sensors, and control the plurality of actuators to generate at least one of a cancellation wave, a subharmonic wave, and a superharmonic wave, based on the frequency of the fundamental incident wave. In addition, a reflected fundamental wave, the sub harmonic wave, and/or the superharmonic wave can be steered to a desired direction or path along the substrate.

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: 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: 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.