Abstract: A thermal-mechanical linear actuator can include a first stage comprising one of a positive coefficient of thermal expansion (“CTE”) material or a negative CTE material and a second stage comprising the other of the positive CTE material or the negative CTE material. The second stage can be at least partially inserted into the first stage. The actuator can further comprise a thermal isolator disposed between the first stage and the second stage to thermally isolate the first stage from the second stage. Heat inputs can be provided where the heat inputs can control the temperature of the first and second stages independently. A hyperbolic meta material can be wrapped or coated around the first stage.

Abstract: A measurement system utilizing metasurfaces and compressive sensing is provided that measures specular and diffuse RF reflection properties of a sample omnidirectionally across a broad frequency regime in a monostatic, bistatic, or BRDF sense. The measurement system may be used to measure the full hemispherical (or spherical) reflection from a target that has been illuminated in a monostatic or bistatic case. The measurement system may also be used to measure the full BRDF of a sample or spatially complex bistatic reflections from a sample.

Abstract: An acoustic bidirectional reflectance distribution function (BRDF) measurement system utilizing metamaterials and compressive sensing for measuring scattering acoustic profiles (e.g., over large angular regions, such as hemispherical scattering/emitting into two ? steradians or even spherical scattering/emitting over four ? steradians). The measurement system includes one or more acoustic waveguides having a curved receiving surface and made from an acoustic metamaterial configured to encode as a sound signal a frequency and directionality of a sound input received from a sample. Each acoustic waveguide includes an acoustic sensor for detecting the encoded sound signal from the metamaterial.

Abstract: A measurement system utilizing metasurfaces and compressive sensing is provided that measures specular and diffuse RF reflection properties of a sample omnidirectionally across a broad frequency regime in a monostatic, bistatic, or BRDF sense. The measurement system may be used to measure the full hemispherical (or spherical) reflection from a target that has been illuminated in a monostatic or bistatic case. The measurement system may also be used to measure the full BRDF of a sample or spatially complex bistatic reflections from a sample.

Abstract: An acoustic bidirectional reflectance distribution function (BRDF) measurement system utilizing metamaterials and compressive sensing for measuring scattering acoustic profiles (e.g., over large angular regions, such as hemispherical scattering/emitting into two ? steradians or even spherical scattering/emitting over four ? steradians). The measurement system includes one or more acoustic waveguides having a curved receiving surface and made from an acoustic metamaterial configured to encode as a sound signal a frequency and directionality of a sound input received from a sample. Each acoustic waveguide includes an acoustic sensor for detecting the encoded sound signal from the metamaterial.

Abstract: An absorption element for absorbing radiation incident on the element at a certain wavelength band. The element includes a surface defining a normal direction perpendicular to the surface. The element also includes an array of a plurality of spaced apart nano-pillars extending from the surface at an angle orientation other than the normal direction, which creates angular asymmetry so as to increase the element's absorption response in a particular direction. The nano-pillars are made of a suitable semiconductor material and have a size relative to the wavelength band to absorb the radiation. In one non-limiting embodiment, the nano-pillars are angled at 45° relative to the normal direction and are cone-shaped to broaden their absorption capabilities.

Abstract: An absorption element for absorbing radiation incident on the element at a certain wavelength band. The element includes a surface defining a normal direction perpendicular to the surface. The element also includes an array of a plurality of spaced apart nano-pillars extending from the surface at an angle orientation other than the normal direction, which creates angular asymmetry so as to increase the element's absorption response in a particular direction. The nano-pillars are made of a suitable semiconductor material and have a size relative to the wavelength band to absorb the radiation. In one non-limiting embodiment, the nano-pillars are angled at 45° relative to the normal direction and are cone-shaped to broaden their absorption capabilities.

Abstract: A metamaterial resonator structure having a size for resonating a predetermined frequency band. The resonator structure includes one or more dielectric slabs each having a top surface and a bottom surface. A conductive resonator element is configured on the top surface of each dielectric slab and has a crescent shape including a center portion and opposing rounded end portions defining a gap therebetween, where the center portion has a wider dimension then the end portions so that a width of the element gradually tapers from the center portion to the end portions, and where the conductive element has a diameter that is a fraction of a wavelength of the frequency band. Several dielectric slabs can be stacked on top of each other, where each slab has a different size and each conductive resonator element is a different size so that each resonator resonates a different portion of the frequency band.

Abstract: An exemplary apparatus attenuates sound in a frequency range, e.g. audible frequencies. A resilient planar membrane has first and second honeycombs with unit cells attached to opposing sides of the planar membrane. Each unit cell has rigid walls extending perpendicular to the planar membrane. Buttresses are mounted inside the unit cells where dimensions of the buttresses result in an alteration of an attenuation versus frequency characteristic in the audible or other frequencies relative to an attenuation versus frequency characteristic without the buttresses.

Abstract: Systems and methods are provided for redirecting electromagnetic radiation around an object. A first assembly, including a first interior wall and a first exterior wall enclosing a propellant gas, substantially encloses the object. A first control system is configured to energize the propellant gas to provide a first volume of plasma and control an electron number density of the first volume of plasma. The electron number density of the first volume of plasma is selected to minimize reflection of the electromagnetic radiation from the first exterior wall. A second assembly includes a second interior wall and a second exterior wall enclosing a propellant gas and is substantially concentric with the first assembly and substantially encloses the object. A second control system is configured to energize the propellant gas to provide a second volume of plasma and control an electron number density of the second volume of plasma.