224results about How to "Reduce frequency" patented technology

System and method for efficient filtering of data set addresses in a web crawler

A web crawler stores fixed length representations of document addresses in a buffer and a disk file, and optionally in a cache. When the web crawler downloads a document from a host computer, it identifies URL's (document addresses) in the downloaded document. Each identified URL is converted into a fixed size numerical representation. The numerical representation may optionally be systematically compared to the contents of a cache containing web sites which are likely to be found during the web crawl, for example previously visited web sites. The numerical representation is then systematically compared to numerical representations in the buffer, which stores numerical representations of recently-identified URL's. If the representation is not found in the buffer, it is stored in the buffer. When the buffer is full, it is ordered and then merged with numerical representations stored, in order, in the disk file. In addition, the document corresponding to each representation not found in the disk file during the merge is scheduled for downloading. The disk file may be a sparse file, indexed to correspond to the numerical representations of the URL's, so that only a relatively small fraction of the disk file must be searched and re-written in order to merge each numerical representation in the buffer.

Motion and still isolation master-slave cooperative control double superior satellite platform

InactiveCN104477410AReduce frequencyRelieve pressureArtificial satellitesSatelliteMagnet
The invention provides a motion and still isolation master-slave cooperative control double superior satellite platform. The platform comprises a plurality of magnetic suspension mechanisms, a load cabin and a service cabin, wherein the load cabin is connected with the service cabin through the magnetic suspension mechanisms; the butt joint faces of the magnetic suspension mechanisms opposite to the load cabin and the service cabin are symmetrically spaced from one another in parallel or vertically; the center point connecting lines of symmetrically arranged magnetic suspension mechanisms are perpendicular to the mass center connecting line of the load cabin and the service cabin. The load cabin and the service cabin are independent of each other in structure, wherein the load cabin is provided with a magnetic suspension mechanism magnet part and is a still cabin section, the service cabin is provided with a magnetic suspension mechanism coil part and is a motion cabin section, the two cabins are not in contact through the non-contact magnetic suspension mechanisms, the service cabin vibrates and the interference is not transmitted to the load cabin, so that the effect that the effective load keeps still in a moving environment and the motion and the still of the two cabins are isolated is achieved.

Device and method for generating 8 times frequency optical millimeter waves by utilizing lithium niobate modulator

InactiveCN101599800AReduce response frequency requirementsReduce frequencyElectromagnetic transmission optical aspectsNon-linear opticsPhysicsSideband
The invention discloses a device and a method for generating 8 times frequency optical millimeter waves by utilizing a lithium niobate modulator, mainly applicable to the generation of optical millimeter waves in the radio over fiber (RoF) network. The method as shown in the attached figure comprises the following steps: high-level sideband is generated on the deep modulated nonlinearity by utilizing lithium niobate nested Mach-Zehnder modulator; the sideband interference of 4n+1, 4n+2, and 4n+3 stages can be countervailed under proper voltage offset; the optical wave is inhibited by a filter; as the sideband amplitude of the eighth and higher stages is less than that of the fourth stage sideband, the optical millimeter wave signals are mainly composed of the +/- four stage sideband of which the frequency interval equals to eight times of the local oscillator frequency, and the electric millimeter wave frequency generated by the beat frequency of a photoelectric detector is eight times of the local oscillator frequency of radio frequency. The method has the advantages of low needed local oscillator frequency and modulator response frequency, no amplitude fading of the generated optical millimeter waves when transmitting in the optical fiber, narrow width of the radio frequency signal wires generated during photoelectric transformation and the like, thus having good application prospect.
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