Abstract: To provide fast access times with very large key fields, an associative memory utilizes a location addressable memory and lookup table to generate from a key the address in memory storing an associated record. The lookup tables, stored in memory, are constructed with the aid of arithmetic data compression methods to create a near perfect hashing of the keys. For encoding into the lookup table, keys are divided into a string of symbols. Each valid and invalid symbol is assigned an index value, such that the sum of valid index values for symbols of a particular key is a unique value that is used as an address to the memory storing the record associated with that key, and the sum of keys containing invalid index values point to a location in memory containing similar data. Utilizing the lookup tables set and relational operations maybe carried out that provide a user with a maximum number of key records resulting from a sequence of intersection, union and mask operations.

Abstract: A fluid impeller, such as a fan for moving air or gases, includes one or more rotatable fluid impelling blades; a flow guiding member adjacent to an edge of the blades, and at least one blade facing surface of the flow guiding member being formed substantially as a segment of a sphere of radius r1 about a center of curvature. Each blade has a flow guiding member abutting edge curved substantially to fit against a sphere of radius r1.