摘要:
A scheme is used to automatically discover algebraic constraints between pairs of columns in relational data. The constraints may be “fuzzy” in that they hold for most, but not all, of the records, and the columns may be in the same table or different tables. The scheme first identifies candidate sets of column value pairs that are likely to satisfy an algebraic constraint. For each candidate, the scheme constructs algebraic constraints by applying statistical histogramming, segmentation, or clustering techniques to samples of column values. In query-optimization mode, the scheme automatically partitions the data into normal and exception records. During subsequent query processing, queries can be modified to incorporate the constraints; the optimizer uses the constraints to identify new, more efficient access paths. The results are then combined with the results of executing the original query against the (small) set of exception records.
摘要:
The present invention relates to a process for the alkoxylation of a monool with at least one alkoxylating agent to an alkoxylated alcohol wherein a catalyst is employed which comprises a metallo-organic framework material of metal ions and at least bidentate coordinately bound organic ligands.
摘要:
Provided is a method for modeling the cost of XML as well as relational operators. As with traditional relational cost estimation, a set of system catalog statistics that summarizes the XML data is exploited; however, the novel use of a set of simple path statistics is also proposed. A new statistical learning technique called transform regression is utilized instead of detailed analytical models to predict the overall cost of an operator. Additionally, a query optimizer in a database is enabled to be self-tuning, automatically adapting to changes over time in the query workload and in the system environment.
摘要:
The invention relates to reinforced polyurethane-urea elastomers with a specific urea content and a specific urethane content, to sheet polyurethane moldings with high surface energy and good lacquer adhesion produced therefrom, and to their use.
摘要:
The present invention provides release agents and plastics moldings and a process for their production using particular additives which reduce the concentration of undesirable, potentially harmful substances in the edge zone and on the surface of the molding, without adversely influencing the other mechanical properties.
摘要:
The present invention relates to a process for the alkoxylation of a monool with at least one alkoxylating agent to an alkoxylated alcohol wherein a catalyst is employed which comprises a metallo-organic framework material of metal ions and at least bidentate coordinately bound organic ligands.
摘要:
Activators with reduced volatility that are liquid at room temperature are obtained as the reaction product of (A) a secondary amine or primary alcohol having at least one tertiary amine group, (B) a polyisocyanate of the diphenylmethane series having a functionality of from 2.5 to 4.0 and an OH-functional reactive component capable of addition to isocyanate. These activators are useful for the production of polyurethane foams having improved emission behavior.
摘要:
Polyurethane elastomers are produced by reacting a polyether and/or polyester polyol having a starter functionality of at least 2 with an NCO-terminated prepolymer produced with a polyether and/or polyester polyol having a starter functionality of at least 4. These polyurethane elastomers exhibit improved processing characteristics combined with a high heat distortion temperature.
摘要:
A process is described for producing pressed materials, particularly wood particle boards, by the hot compaction of raw materials containing lignocellulose which are mixed and/or impregnated with polyisocyanates as binders, with the use of latent, thermally activatable catalysts, wherein ammonium salts from the reaction of amines with malonic acid are used as catalysts.
摘要:
A belt adjusting device comprises a belt webbing having a free end and a tensioned section. The belt adjusting device further comprises a holding part provided with a through passage for a belt webbing and a contact surface adjacent to the through passage. The contact surface is inclined relatively to a plane in which the through passage extends. The belt adjusting device further comprises an arresting part which is movable relatively to the holding part and comprises a deflection web. The deflection web comprises a clamping surface on its side facing the holding part. The belt webbing runs through the through passage, around the deflection web and back through the through passage. The free end of the belt webbing passes through the through passage between an edge of the through passage adjacent the contact surface and the tensioned section of the belt webbing.