Abstract: The present disclosure provides system and methods for optimizing the tuning of impedance elements associate with sub-wavelength antenna elements to attain target radiation and/or field patterns. A scattering matrix (S-Matrix) of field amplitudes for each of a plurality of modeled lumped ports, N, may be determined that includes a plurality of lumped antenna ports, Na, with impedance values corresponding to the impedance values of associated impedance elements and at least one modeled external port, Ne, located external to the antenna system at a specified radius vector. Impedance values may be identified through an optimization process, and the impedance elements may be tuned (dynamically or statically) to attain a specific target radiation pattern.

Abstract: An antenna system includes near-end electromagnetic (EM) radiating elements, a tunable medium, and control circuitry. The tunable medium includes EM scattering elements corresponding to lumped impedance elements and variable impedance control inputs configured to enable selection of an impedance value for each of the lumped impedance elements. The control circuitry is configured to determine a scattering matrix (S-matrix) relating field amplitudes at lumped ports including internal lumped ports and external lumped ports. The internal lumped ports correspond to the lumped impedance elements, and the external lumped ports correspond to the near-end EM radiating elements or far-end near-end EM radiating elements. A method includes determining at least a portion of component values of a desired S-matrix, and adjusting the variable impedance control inputs to modify the impedance value of the lumped impedance elements to cause the S-matrix to at least approximate at least a portion of the desired S-matrix.

Abstract: A determined object wave can be approximately formed by applying a modulation pattern to metamaterial elements receiving RF energy from a feed network. For example, a desired object wave at a surface of an antenna is selected to be propagated into a far-field pattern. A computing system can compute an approximation of the object wave by calculating a modulation pattern to apply to metamaterial elements receiving RF energy from a feed network. The approximation can be due to a grid size of the metamaterial elements. Once the modulation pattern is determined, it can be applied to the metamaterial elements and the RF energy can be provided in the feed network, causing emission of the approximated object wave from the antenna.

Abstract: A determined far-field beam pattern can be approximately formed by applying a modulation pattern to metamaterial elements receiving RF energy from a feed network. For example, a desired beam profile projected onto a two-dimensional plane of a far-field of an antenna is desired to be produced by an antenna. A computing system can calculate a modulation pattern to apply to metamaterial elements receiving RF energy to a feed network that will result in an approximation of desired beam profile.

Abstract: An antenna system includes near-end electromagnetic (EM) radiating elements, a tunable medium, and control circuitry. The tunable medium includes EM scattering elements corresponding to lumped impedance elements and variable impedance control inputs configured to enable selection of an impedance value for each of the lumped impedance elements. The control circuitry is configured to determine a scattering matrix (S-matrix) relating field amplitudes at lumped ports including internal lumped ports and external lumped ports. The internal lumped ports correspond to the lumped impedance elements, and the external lumped ports correspond to the near-end EM radiating elements or far-end near-end EM radiating elements. A method includes determining at least a portion of component values of a desired S-matrix, and adjusting the variable impedance control inputs to modify the impedance value of the lumped impedance elements to cause the S-matrix to at least approximate at least a portion of the desired S-matrix.

Abstract: A method of managing a power supply system for a data center includes circulating a fluid in a cooling circuit, obtaining data regarding a server located in the data center using a sensor, controlling the transfer of heat energy from the server to the fluid based on the data, coupling the fluid to an electrochemical power generator, and generating power for the server using the fluid in the electrochemical power generator.

Abstract: A noise-canceling device includes a processing circuit configured to detect vibrational noise sound waves near a listener's ear using a vibration sensor, generate a vibrational noise-canceling signal, and control operation of a speaker to provide a desired sound signal and the vibrational noise-canceling signal to at least partially cancel the vibrational noise sound waves.

Abstract: An apparatus for reducing electromagnetic scattering includes a first component having a plurality of curved segments, each including a first reflective material, and together forming an enclosed cavity; and a second component having a plurality of flat or cylindrically-curved segments, each comprising a second reflective material. The second component is positioned external to the cavity.

Abstract: Surface scattering antennas with lumped elements provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure. In some approaches, the surface scattering antenna is a multi-layer printed circuit board assembly, and the lumped elements are surface-mount components placed on an upper surface of the printed circuit board assembly. In some approaches, the scattering elements are adjusted by adjusting bias voltages for the lumped elements. In some approaches, the lumped elements include diodes or transistors.

Abstract: A fuel tank includes a port and an open-cell foam. The open-cell foam is configured to retain a liquid fuel by an interfacial surface tension between the open-cell foam and the liquid fuel. The open-cell foam is configured to selectively release the liquid fuel when a surfactant is applied to the open-cell foam to reduce the interfacial surface tension between the open-cell foam and the liquid fuel.

Abstract: The present disclosure provides systems and methods associated with mode conversion for electromagnetic field modification. A mode converting structure (holographic metamaterial) is formed with a distribution of dielectric constants chosen to convert an electromagnetic radiation pattern from a first mode to a second mode to attain a target electromagnetic radiation pattern that is different from the input electromagnetic radiation pattern. A solution to a holographic equation provides a sufficiently accurate approximation of a distribution of dielectric constants that can be used to form a mode converting device for use with one or more transmission lines, such as waveguides. One or more optimization algorithms can be used to improve the efficiency of the mode conversion.

Abstract: The present disclosure provides system and methods for calibrating a tunable metamaterial device including a plurality of external antennas. A sequence of port impedance vectors, (z(m), m) may be generated. Each of the port impedance vectors may be applied to the tunable metamaterial device, and measuring at least one S-parameter associated with an antenna external to the tunable metamaterial device. A simulated S-Matrix may be generated by associating each of the port impedance vectors, z(m), with the unknown admittance matrix. The unknown admittance matrix may be solved for by determining a plurality of optimization variables by comparing each of the S-parameters, S(m), to the simulated S-Matrix for each port impedance vector, z(m), and generating an estimated admittance matrix by associating each of the optimization variables with the unknown admittance parameters. The estimated admittance matrix may be used for more accurate radiation patterning.

Abstract: Inter-element couplings between radiative elements of an antenna can be reduced by increasing resonant frequencies for first selected radiative elements and decreasing resonant frequencies for second selected radiative elements. In some approaches, the radiative elements are coupled to a waveguide and the antenna configuration is a hologram that relates a reference wave of the waveguide to a radiated wave of the antenna. In some approaches, the antenna configuration is modified by identifying stationary points of the hologram and then staggering resonant frequencies for radiative elements within neighborhoods of the stationary points.

Abstract: Modulation patterns for surface scattering antennas provide desired antenna pattern attributes such as reduced side lobes and reduced grating lobes.

Abstract: A power supply system for a data center includes a cooling circuit, an electrochemical power generator, a sensor, and a processor. The cooling circuit includes a fluid configured to receive heat energy generated by a server located in the data center. The electrochemical power generator is configured to receive and/or generate the fluid of the cooling circuit and to generate electrical energy for the server using the fluid. The sensor is configured to obtain data regarding the server. The processor is configured to control an amount of heat energy transferred from the server to the fluid based on the data.

Abstract: Antenna systems and related methods are disclosed. An antenna system includes an antenna controller configured to operably couple to an array of electromagnetic (EM) scattering elements. The controller is configured to determine a performance parameter of the antenna system for a plurality of different combinations of different spatial holographic phases and effective mode indices having different modulation patterns corresponding thereto, and select one of the modulation patterns based on the performance parameter corresponding thereto. A method includes storing data indicating a modulation pattern determined based on a spatial holographic phase and an effective mode index for each of a plurality of different main beam angles from the antenna, and controlling the antenna to operate with a main beam pointed in each of the plurality of different main beam angles by controlling the antenna to operate in each modulation pattern corresponding to the plurality of main beam angles.

Abstract: Described embodiments include an apparatus, and a method. An apparatus includes an array of at least two artificially structured electromagnetic unit cells. The at least two artificially structured electromagnetic unit cells are configured to generate a pulse of radiofrequency magnetic field B1 orientated transverse to the quasistatic magnetic field B0 parallel to the z-axis of the bore of a MRI or NMR device by transforming an incident pulse of radiofrequency electromagnetic waves. The generated pulse having magnetic field intensity sufficient to excite a detectable magnetic resonance in magnetically active nuclei located within at least a portion of an examination region located within the bore. The apparatus includes a radiofrequency electromagnetic wave conducting structure configured to distribute a received pulse of radiofrequency electromagnetic waves as an incident pulse of radiofrequency electromagnetic waves to the at least two artificially structured electromagnetic unit cells.

Abstract: Described embodiments include a system, apparatus, and method. An apparatus includes an array of at least two groups of at least two artificially structured electromagnetic unit cells. Each group of the at least two groups configured to be respectively linearly arranged with respect to the z-axis of the bore of MRI or NMR device. Each group of the at least two groups of artificially structured electromagnetic unit cells configured to transform an incident pulse of radiofrequency electromagnetic waves into a pulse of radiofrequency magnetic field B1 orientated transverse to a segment of the z-axis and spatially proximate to the group. The apparatus includes a radiofrequency electromagnetic wave conducting structure configured to selectably distribute a received pulse of radiofrequency electromagnetic waves to a group of the at least two groups.

Abstract: A lightweight transport vessel transports compressed natural gas underwater without needing to liquefy the gas for transport.

Abstract: Disclosed are antenna systems and related methods. An antenna system includes a plurality of near-end electromagnetic (EM) radiating elements, a tunable medium, and control circuitry. The tunable medium is positioned relative to the plurality of near-end EM radiating elements and a plurality of far-end EM radiating elements to scatter EM radiation transmitted between the plurality of near-end EM radiating elements and the plurality of far-end EM radiating elements. The control circuitry includes a controller operably coupled to the tunable medium. A method includes modifying EM properties of the tunable medium to modify the EM radiation transmitted between the plurality of near-end EM radiating elements and the plurality of far-end EM radiating elements.