43results about How to "Maximizing coefficient" patented technology

An optical fiber coupler capable of providing a low loss, high coupling coefficient interface between conventional optical fibers and optical waveguide devices is provided. The novel coupler, which may be polarization maintaining, if a polarization maintaining preform is used in its fabrication includes a core, a cladding, a first end for interfacing with an optical fiber and a second end for interfacing with an optical waveguide device. The sizes of the core and cladding are gradually reduced from the first end to the second end in accordance with a predetermined reduction profile. Various parameters, such as refractive indices and sizes of the core and cladding and the reduction profile are selected to produce a low numerical aperture at the first end and a high numerical aperture at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end. In another embodiment, the novel coupler includes a secondary cladding which is also reduced between the first and second ends to improve the strength of the coupler structure at the second end. In yet another embodiment, one or two novel couplers are formed along with a chiral fiber based optical waveguide device as a single continuous element. The optical fiber preform used to fabricate the novel optical fiber coupler can be etched prior to fabrication to facilitate application of the reduction profile.

A spectrum sensing method for cognitive radio wherein spectrum holes are detected in a wireless environment having spectrum scarcity. First, a cognitive radio user (CR) determines the power spectral density (PSD) of a wideband signal and detects subbands within the wideband using wavelet transforms (WT). WT coefficients are calculated by convolving the PSD with first derivatives of wavelet smoothing functions. The extrema of the WT coefficients demark frequency subband edges. Detecting subband edges becomes more robust against noise by median filtering the PSD before calculating WT coefficients, summing over WT coefficients with different scale factors, and suppressing WT coefficients below a noise threshold. After identifying subbands, the CR determines subband availability by measuring the subband power and signaling the power to a fusion center receiving power measurements from multiple cooperating CRs, and final decisions are based on data and decision fusion.

An optical fiber coupler array capable of providing multiple low loss, high coupling coefficient interfaces between a predetermined number of low numerical aperture optical fibers and an optical waveguide device with at least a corresponding number of waveguide interfaces. The novel coupler array includes a plurality of coupler inner cores and a plurality of corresponding coupler outer cores, within a medium surrounding each plural outer core, and also includes a first end for interfacing with plural optical fibers and a second end for interfacing with a plurality of waveguide interfaces of an optical waveguide device. The sizes of the inner and outer cores are gradually reduced from the first end to the second end in accordance with at least one predetermined reduction profile. Various parameters, such as refractive indices and sizes of the inner and outer cores and the medium (as well as the reduction profile) are selected to produce a plurality of low numerical aperture waveguides at the first end, and a plurality of high numerical aperture waveguides at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end. Advantageously, the novel coupler array may be fabricated as an array of individually drawn couplers from multiple parallel fused performs (arranged in a row, or in another geometric cross section). Alternately, the novel coupler array may be fabricated from a single perform (glass or polymer) embedded with a plurality of parallel inner and outer core sets.

The invention relates to a swimming pool heating system, characterized in that it comprises a heat pump and means for controlling the compressor of said heat pump according to a number of non-zero power levels, as a function of a predetermined set of parameters. The system comprises, for example, three power levels, the first level being close to 40% of the compressor speed, the second level being close to 70% of the compressor speed, and the third level being close to 100% of the maximum compressor speed.

An optical fiber coupler array capable of providing multiple low loss, high coupling coefficient interfaces between a predetermined number of low numerical aperture optical fibers and an optical waveguide device with at least a corresponding number of waveguide interfaces. The novel coupler array includes a plurality of coupler inner cores and a plurality of corresponding coupler outer cores, within a medium surrounding each outer core, and also includes a first end for interfacing with optical fibers and a second end for interfacing with a plurality of waveguide interfaces of an optical waveguide device. The sizes of the inner and outer cores are gradually reduced from the first end to the second end in accordance with at least one predetermined reduction profile, such that the coupler array comprises a plurality of low numerical aperture waveguides at the first end, and a plurality of high numerical aperture waveguides at the second end.

An optical fiber coupler array capable of providing multiple low loss, high coupling coefficient interfaces between a predetermined number of low numerical aperture optical fibers and an optical waveguide device with at least a corresponding number of waveguide interfaces. The novel coupler array includes a plurality of coupler inner cores and a plurality of corresponding coupler outer cores, within a medium surrounding each plural outer core, and also includes a first end for interfacing with plural optical fibers and a second end for interfacing with a plurality of waveguide interfaces of an optical waveguide device. The sizes of the inner and outer cores are gradually reduced from the first end to the second end in accordance with at least one predetermined reduction profile. Various parameters, such as refractive indices and sizes of the inner and outer cores and the medium (as well as the reduction profile) are selected to produce a plurality of low numerical aperture waveguides at the first end, and a plurality of high numerical aperture waveguides at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end. Advantageously, the novel coupler array may be fabricated as an array of individually drawn couplers from multiple parallel fused performs (arranged in a row, or in another geometric cross section). Alternately, the novel coupler array may be fabricated from a single perform (glass or polymer) embedded with a plurality of parallel inner and outer core sets.

The present invention provides a transmissibility shaping control for active suspension systems. The T-shaping control is a combination of several sub-strategies using the dynamic information in the frequency domain. Each strategy works dominantly in a certain frequency range to achieve a desirable transmissibility for better suspension performance in the corresponding frequency range. Different sub-strategies for different frequency ranges include stiffness control, skyhook control, groundhook control, and various damping levels. In addition, an embodiment is provided utilizing tunable compressible fluid struts in an active vehicle suspension.

Antennas and antenna mandrels or assemblies may be designed and configured to enable one of one- or two-way communication and / or power transfer with mechanical devices such as ophthalmic devices, including contact lenses. These antennas and antenna mandrels or assemblies may be utilized to transmit data from the mechanical devices to receive data from a transmitter, and / or inductively charge an electromechanical cell or the like incorporated into a mechanical device.

A membrane electrode assembly (MEA) for a fuel cell comprising a catalyst layer and a method of making the same. The catalyst layer can include a plurality of catalyst nanoparticles, e.g., platinum, disposed on buckypaper. The catalyst layer can have 1% or less binder prior to attachment to the membrane electrode assembly. The catalyst layer can include (a) single-wall nanotubes, small diameter multi-wall nanotubes, or both, and (b) large diameter multi-wall nanotubes, carbon nanofibers, or both. The ratio of (a) to (b) can range from 1:2 to 1:20. The catalyst layer can produce a surface area utilization efficiency of at least 60% and the platinum utilization efficiency can be 0.50 gPt / kW or less.

A membrane electrode assembly (MEA) for a fuel cell comprising a catalyst layer and a method of making the same. The catalyst layer can include a plurality of catalyst nanoparticles, e.g., platinum, disposed on buckypaper. The catalyst layer can have 1% or less binder prior to attachment to the membrane electrode assembly. The catalyst layer can include (a) single-wall nanotubes, small diameter multi-wall nanotubes, or both, and (b) large diameter multi-wall nanotubes, carbon nanofibers, or both. The ratio of (a) to (b) can range from 1:2 to 1:20. The catalyst layer can produce a surface area utilization efficiency of at least 60% and the platinum utilization efficiency can be 0.50 gPt / kW or less.

A membrane electrode assembly (MEA) for a fuel cell comprising a gradient catalyst structure and a method of making the same. The gradient catalyst structure can include a plurality of catalyst nanoparticles, e.g., platinum, disposed on layered buckypaper. The layered buckypaper can include at least a first layer and a second layer and the first layer can have a lower porosity compared to the second layer. The gradient catalyst structure can include single-wall nanotubes, carbon nanofibers, or both in the first layer of the layered buckypaper and can include carbon nanofibers in the second layer of the layered buckypaper. The MEA can have a catalyst utilization efficiency of at least 0.35 gcat / kW or less.

A method of operating a wind turbine having a rotor with a plurality of blades, and one or more pitch mechanisms for rotating the blades including a sub-nominal zone of operation and a supra-nominal zone of operation for wind speeds above the nominal wind speed wherein the sub-nominal zone of operation includes a first, a second and a third operational range. The first operational range extends from a cut-in wind speed to a first wind speed, wherein the rotor speed is kept substantially constant at a first value. The second operational range extends from the first wind speed to a second wind speed, wherein both the rotor speed and generator torque are varied as a function of wind speed. The third operational range extends from the second wind speed to the nominal wind speed, wherein the rotor speed is kept substantially constant at a second value, and wherein in the second operational range, the generator torque, T, is determined in accordance with T=k·co2, wherein co is the generator speed and k is non-constant over the second operational range.

The invention includes linkage assemblies comprising coupled links with metallic contact surfaces with improved stiffness. The inventors found significant mechanical problems with all previous descriptions of metallic contact links sufficient to preclude their commercial use. These metallic contact links are a significant improvement over existing plastic ball and metal joint, or all plastic beads as found in the prior art. The invention includes methods providing these links and high friction couplings between them, as well as the linkage assemblies and flexible arms resulting from these processes.

A method of operating a wind turbine having a rotor with a plurality of blades, and one or more pitch mechanisms for rotating the blades is disclosed. The method comprises a sub-nominal zone of operation and a supra-nominal zone of operation for wind speeds above the nominal wind speed. The sub-nominal zone of operation comprises a first, a second and a third operational range. The first operational range extends from a cut-in wind speed to a first wind speed, wherein the rotor speed is kept substantially constant at a first value. The second operational range extends from the first wind speed to a second wind speed, wherein both the rotor speed and generator torque are varied as a function of wind speed. The third operational range extends from the second wind speed to the nominal wind speed, wherein the rotor speed is kept substantially constant at a second value, and wherein in the second operational range, the generator torque, T, is determined in accordance with T=k·ω2, wherein ω is the generator speed and k is non-constant over the second operational range.