Detecting the temporal gaps of technology fronts: A case study of smart grid field

This study aims to propose a methodology that describes the technology fronts evolution and compares the temporal gaps between two specialties. Using the patent documents of a local country, the United States (US), as well as the global context in the smart grid technology as the example, highly cited patents were collected from 2001 to 2010 and divided into a series of overlapping snapshots in which patent citation networks were constructed through bibliographic coupling (BC) analysis. A rolling clustering and features extraction procedure were applied for segmenting networks into clusters and then mapping these clusters into the technology trajectory maps. Next we describe the state of global and the US smart grid development, and then place the US trajectories in the global context to explore the temporal relationship between them. Technology fronts in this study can be categorized into four types - frontrunner, follower, uniquer, and behinder - according to the matching criteria and the temporal gap index. The results show that a high percentage of US technology fronts can be classified as frontrunners or uniquers; the nation occupies a leading position worldwide in developing each sub-domain of smart grid technology. (C) 2012 Elsevier Inc. All rights reserved.