Abstract: A preparation method for polyoxymethylene dimethyl ether (DMMn, generally, n=3-8 or 2-8) and mixture thereof may include one or more of the following: mixture of aqueous formaldehyde solution and polyalcohol is heated and dehydrated under vacuum conditions to yield flowing polyoxymethylene containing low moisture, which is heated and gasified to obtain relatively pure gaseous formaldehyde, which is mixed with methylal, previous batch of low-boiling-point substances applied, macromolecules, etc. in presence of catalyst. Or, the method mainly includes: aqueous formaldehyde solution, polyalcohol, and previous batch of macromolecular mixture applied are heated under vacuum conditions to remove moisture so as to obtain anhydrous flowable polyoxymethylene etherate, which is mixed with methylal, previous batch of low-boiling-point substances applied, macromolecules, etc. in presence of catalyst.

Abstract: Architecture that operates in combination with an integrated search framework to derive user intent associated with a search query, and then based on the derived intent, choose the search method: a local search on the current local device from which the search is initiated, a non-local search of data sources other than the local device, or both the local search and the non-local search. The query context can be derived to more effectively assess the query intent. The architecture employs predictive models trained with candidate features that enable the prediction of a singular intent (or degree of intent) in the integrated search environment. The models can be trained using historical and real-time features. A classifier is trained using the features. The user intent is then derived based on the classifier output and the search is performed accordingly.