Irvine-based ad network Specific Media said this morning that it has acquired a Amsterdam-based firm, AdCombination, as part of an European expansion. Financial terms of the buy were not disclosed. Specific Media said the acquisition of AdCombination expands its operations into the Netherlands, Belgium, and Luxembourg. The company claims the move will make it the largest, independent digital media platform in Europe. Specific Media is headed by Tim Vanderhook.