Abstract: An improved method and system for synchronization-replication concurrency maintain a history table for a data table in a mirror, where the history table can include redundant version values that indicate a period in which data values corresponding to the version values are valid. Replication can thus be performed between a source and a mirror for a current version of the data table, while synchronization is simultaneously performed between the mirror and a client for an earlier version of the data table using the history table. Simultaneous reads, writes, and read-writes are possible while maintaining data reliability. The replication and synchronization processes can be performed at the read-uncommitted isolation level to increase efficiency. The method and system thus increase overall data throughput, reduce client response time, and dramatically enhance end-user satisfaction.

Abstract: A method and system for efficient snapshot querying include: providing a first version value for each data in a history table, where the first version value indicates a beginning of a period in which the data is valid; providing at least a second version value for each data in the history table, where the second version value indicates an end of the period in which the data is valid; receiving a request for a version of a database; and retrieving the data with the first version value less than or equal to the requested version and the second version value greater than or equal to the requested version. By maintaining a history table with redundant version information, the method and system are able to provide efficient snapshot querying while also avoiding the overhead burden of conventional approaches. No aggregates, joins, or sub-queries are required to retrieve a snapshot.

Abstract: A method and system for synchronizing data on a first device with data at a second device, includes: determining a pre-image of the data on the first device according to a filter after a previous synchronization with the data at the second device; determining a current image of the data at the second device according to the filter; determining a delta of the current image, where the delta comprises data that exists in the current image and has changed since the previous synchronization; instructing the first device to delete data that exists in the pre-image but not in the current image; and instructing the first device to UPSERT a union of the data that exists in the delta and the data that exists in the current image but not the pre-image. This is efficient in time and bandwidth resources while also providing consistent data integrity.

Abstract: An attenuator of electromagnetic radiation, such as radar, is described wherein a single attenuator sheet in the nature of "spacecloth" is placed in front of a plurality of reflective layers wherein each of the reflective layers is tuned to reflect a narrow band of radiation of a selected frequency and transmit other frequencies; and each of the reflective layers is spaced from the attenuation layer at a distance of one-fourth of the wavelength of electromagnetic radiation to which it is tuned. In a preferred embodiment each of the reflective layers comprises elongated narrow conductive areas arranged in spaced apart columns and rows in a generally non-conductive area.

Abstract: A process for generating electrically conductive patterns on a dielectric substrate, such as an insulating sheet, which comprises applying to preselected areas of the substrate a preselected concentration of an ink in the form of an oxidizing agent, such as a solution of a ferric salt, e.g., ferric chloride or ferric ethylbenzenesulfonate, and which can also contain a suitable binder or thickening agent, to form printed images on the substrate surface. The resulting printed surface of the substrate is then exposed to an excess of reactant, e.g., pyrrole monomer in vapor phase, which reacts with the oxidizing agent to develop conductive images, as by forming polypyrrole, in those printed areas of the substrate containing the oxidizing agent.

Abstract: Production of electrically conductive composite or structural materials comprising a dielectric substrate, e.g. fiberglass fabric, and a layer of a pyrrole polymer on the substrate, by treating the substrate with a solution of a strong oxidant containing a substantially non-nucleophilic anion, e.g. ferric chloride, drying the substrate and exposing the so treated substrate with the vapors of a pyrrole and oxidizing the pyrrole by the strong oxidant and depositing a polypyrrole layer or film on the substrate.

Abstract: Electrically conductive composites comprising a dielectric porous substance, e.g. fiberglass fabric, and a pyrrole polymer deposited in the pores of such substance. The composites are produced by contacting the porous substance with an anode in an electrolytic cell containing an electrolyte comprising a pyrrole monomer and a substantially non-nucleophilic anion such as bisulfate, and passing an electric current through the cell, thus electrochemically precipitating a conductive pyrrole polymer in the pores of such substance.

Abstract: An interference type radar attenuator is described formed of a plurality of thin sheets having selected admittance values. The sheets are spaced apart by thin plastic spacer members having a shape memory so that the sheets can be compressed together by deforming the plastic spacers for very tight packaging and, upon release of the packaging, the sheets return to a spaced relation for effective radar attenuation. A similar structure is useful in space vehicles for thermal shielding and as a meteroid bumper.