clustering of a given document space can preferably apply hybrid techniques using citation-link and both clustering. This approach is used to improve efficiency with respect to the two individual components when separately applied and thus to overcome some of
. In recent studies (Glänzel and Thijs 2011a , b ), this notion was extended to hybrid methods with two components, particularly bibliographic coupling and textual similarity. The textual component was based on term frequencies, where terms were
, but between the two documents under consideration.
Finally, there are several examples of successful hybrid methods (e.g., Cao and Gao 2005 ; Glenisson et al. 2005 ; Janssens et al. 2006 ), where citation and text-based approaches are
. In this case, the links among domestic innovators are not so strong, and the “Death Valley” problem is aggravating. The fields of emerging technology like nano and fusion technology are kinds of “hybrid innovation” patterns