Abstract: A method includes receiving a wafer, measuring a surface topography of the wafer; calculating a topographical variation based on the surface topography measurement performing a single-zone alignment compensation when the topographical variation is less than a predetermined value or performing a multi-zone alignment compensation when the topographical variation is greater than the predetermined value; and performing a wafer alignment according to the single-zone alignment compensation or the multi-zone alignment compensation.

Abstract: A method, computer system, and computer program product for data monitoring management are provided. A first invalid zero value candidate from a data stream is received. A memory location for the first invalid zero value candidate is received. At a first time an access connection to the memory location is established. At a second time subsequent to the first time the access connection to the memory location is checked. Based on the checking, a determination is made whether the first invalid zero value candidate contains an invalid zero value.

Abstract: A perfluoro surfactant and a preparation method therefor. A carbon fluorine bond is not prone to break when the perfluoro surfactant is used as an emulsifier in a fluorine polymer reaction, such that the average molecular weight of a fluorine polymer generated in the fluorine polymer reaction is significantly increased. The preparation method is implemented in a continuous micro-channel reaction system, where the retention time of a reactant in the reaction system can be greatly shortened to few minutes or even seconds, a back-mixing phenomenon in the reaction system can be basically eliminated, and thus the occurrence of a side reaction, an optical coupling reaction, can be greatly reduced. There are reaction stages comprising an ozonization reaction and a photo-oxidation reaction.

Abstract: A method and an apparatus for selecting a reference tag used for positioning are provided. The method includes: obtaining first signal strength emitted by a reference tag and second signal strength emitted by a tag to be positioned, where the first signal strength and the second signal strength are detected by each radio frequency reader; comparing the first signal strength with the second signal strength to determine a boundary of the radio frequency readers, and dividing a network into a first area and a second area with the boundary; determining an estimated direction of the tag to be positioned relative to the reference tag according to a relative position of the reference tag and the boundary; and according to the estimated direction and according to the specified number of reference tags, selecting a valid reference tag group as the reference tag used for positioning.